Inter War years (Between 1st and 2nd World War) Research Paper

Inter War years (Between 1st and 2nd World War) - Research Paper Example Overall this era set the foundation for what was to come ahead in form of Second world war and the cold war that followed afterwards. The inter war period can be termed as bridge era between the two major wars. It had its economic impacts, political, geographical and almost all important factors that determine the fate of any nation and region. This era can be stretched from the November 1918 and the most notable of those months and event was the Treaty of Versailles (Slavicek 2010), which according to many critiques and historians served as the reason towards the Second World War. The treaty of Versailles had its own importance and impact on the history. This treaty was full of many clauses and aspects which left deep animosity in the hearts of Germans. The lone clause of â€Å"war guilt† ( Ringer 2005, 72) served more severe than any. This clause had political, geographical as well as strategic repercussions. Areas of strategic importance were taken from Germany, large repar ations were imposed on them, their military might was cut to pieces and various other aspects which left bitter feeling in the hearts of Germans and made them resolve them taking revenge in upcoming years. The sick man of Europe, Turkey and the Ottoman Empire was on its last leg, and these days served its ending season. The empire officially came to an end (Al-Rasheed 2002, 2). As a result of defeat and ultimately treaty, the Ottoman Empire collapsed and Turkey was reduced to a small unit. Turkey the former Ottoman Empire had to cede many areas and areas like Cyprus and Mesopotamia were separated from the Mega Empire and United Kingdom performed the honors and over took these areas. Other event that took place in parallel was that of creation of Irish state. While revolts and unrest had erupted couple of years back, but it has to settle down only at the end of the war, when Great Britain finally gave up to the demand of Irish people and allowed it creating its own borders and state with its over sovereign government and representation. Other notable event that took place the rise of Egypt and new state development in that part. While it had remained a colony and an occupied land in the 19th century under Napoleon and remained a land of strategic importance, eventually became independent from the status of British colony. The establishment of League of Nations was another major event that took place during the inter war period (Sengupta 2008, 173). The aim of this entity was to ensure no war of similar sort takes place again, it did pass number of resolutions, made some treaties, interventions were introduced, yet it could not live up to the expectation and seeing in a longer run, League of nation could not revert the deadly war that was awaiting the world and humanity. The Russian revolution in the name of socialism came into full force as well ((Smele 2006). This was the period of 1923 to 1924. As it is being said, that the first causality of war is humanity, it was the case in this regard as well. Much was invested over the military might, and the human suffering was exposed both in from of war and the inter period where the mighty nations spent more on ensuring mighty military than helping the poor. The soviet republic was a worse example in this regard and human suffering w

Hydrolic Fracking Research Paper Essay Example for Free

Hydrolic Fracking Research Paper Essay Hydraulic fracturing is a process used in nine out of 10 natural gas wells in the United States, where millions of gallons of water, sand and chemicals are pumped underground to break apart the rock and release the gas. Scientists are worried that the chemicals used in fracturing may pose a threat either underground or when waste fluids are handled and sometimes spilled on the surface. The natural gas industry defends hydraulic fracturing, better known as fracking, as safe and efficient. Thomas J. Pyle, president of the Institute for Energy Research, a pro-industry non-profit organization, claims fracking has been â€Å"a widely deployed as safe extraction technique,† dating back to 1949. What he doesn’t say is that until recently energy companies had used low-pressure methods to extract natural gas from fields closer to the surface than the current high-pressure technology that extracts more gas, but uses significantly more water, chemicals, and elements. The industry claims well drilling in the Marcellus Shale will bring several hundred thousand jobs, and has minimal health and environmental risk. President Barack Obama in his January 2012 State of the Union, said he believes the development of natural gas as an energy source to replace fossil fuels could generate 600,000 jobs. However, research studies by many economists and others debunk the idea of significant job creation. Barry Russell, president of the Independent Petroleum Association of America, says â€Å"no evidence directly connects injection of fracking fluid into shale with aquifer contamination.† Fracking â€Å"has never been found to contaminate a water well,† says Christine Cronkright, communications director for the Pennsylvania Department of Health. Research studies and numerous incidents of water contamination prove otherwise. In late 2010, equipment failure may have led to toxic levels of chemicals in the well water of at least a dozen families in Co noquenessing Township in Bradford County. Township officials and Rex Energy, although acknowledging that two of the drilling wells had problems with the casings, claimed there were pollutants in the drinking water before Rex moved into the area. John Fair disagrees. â€Å"Everybody had good water a year ago,† Fair told environmental writer and activist Iris Marie Bloom in February 2012. Bloom says residents told her the color of water changed to red, orange, and gray after Rex began drilling. Among the chemicals detected in the well water, in addition to methane gas, were ammonia, arsenic, chloromethane, iron, manganese, t-butyl alcohol, and toluene. While not acknowledging that its actions could have caused the pollution, Rex did provide fresh water to the residents, but then stopped doing so on Feb. 29, 2012, after the Pennsylvania Department of Environmental Protection (DEP) said the well water was safe. The residents absolutely disagreed and staged protests against Rex; environmental activists and other residents trucked in portable water jugs to help the affected families. The Marcellus Outreach Butler blog (MOB) declared that residents’ â€Å"lives have been severely disrupted and their health has been severely impacted. To just ‘close the book’ on investigations into their troubles when so many indicators point to the accountability of the gas industry for the disruption of their lives is unbelievable . In April 2011, near Towanda, Pa., seven families were evacuated after about 10,000 gallons of wastewater contaminated an agricultural field and a stream that flows into the Susquehanna River, the result of an equipment failure, according to the Bradford County Emergency Management Agency.The following month, DEP fined Chesapeake Energy $900,000, the largest amount in the state’s history, for allowing methane gas to pollute the drinking water of 16 families in Bradford County during the previous year. The DEP noted there may have been toxic methane emissions from as many as six wells in five towns. The DEP also fined Chesapeake $188,000 for a fire at a well in Washington County that injured three workers. In January 2012, an equipment failure at a drill site in Susquehanna County led to a spill of several thousand gallons of fluid for almost a half-hour, causing potential pollution, according to the DEP. In its citation to Carizzo Oil and Gas, the DEP strongly recommended that the company cease drilling at all 67 wells â€Å"until the cause of this problem and a solution are identified.† In December 2011, the federal Environmental Protection Agency concluded that fracking operations could be responsible for groundwater pollution.â€Å"Today’s methods make gas drilling a filthy business. You know it’s bad when nearby residents can light the water coming out of their tap on fire,† says Larry Schweiger, president of the National Wildlife Federation. Whatâ €™s causing the fire is the methane from the drilling operations. A ProPublica investigation in 2009 revealed methane contamination was widespread in drinking water in areas around fracking operations in Colorado, Texas, Wyoming, and Pennsylvania. The presence of methane in drinking water in Dimock, Pa., had become the focal point for Josh Fox’s investigative documentary, Gasland, which received an Academy Award nomination in 2011 for Outstanding Documentary; Fox also received an Emmy for non-fiction directing. Fox’s interest in fracking intensified when a natural gas company offered $100,000 for mineral rights on property his family owned in Milanville, in the extreme northeast part of Pennsylvania, about 60 miles east of Dimock. Research by a team of scientists from Duke University revealed â€Å"methane contamination of shallow drinking water systems that is associated with shale-gas extraction.† The data and conclusions, published in the May 2011 issue of the prestigious Proceedings of the National Academy of Sciences, note d that not only did most drinking wells near drilling sites have methane, but those closest to the drilling wells, about a half-mile, had an average of 17 times the methane of those of other wells. â€Å"Some of the chemicals used in hydraulic fracturing—or liberated by it—are carcinogens,† Dr. Sandra Steingraber told members of the Environmental Conservation and Health committee of the New York State Assembly. Dr. Steingraber, a biologist and distinguished scholar in residence at Ithaca College, pointed out that some of the chemicals â€Å"are neurological poisons with suspected links to learning deficits in children,† while others â€Å"are asthma triggers. Some, especially the radioactive ones, are known to bioaccumulate in milk. Others are reproductive toxicants that can contribute to pregnancy loss.† An investigation by New York Times reporter Ian Urbina, based upon thousands of unreported EPA documents and a confidential study by the natural gas industry, concluded, â€Å"Radioactivity in drilling waste cannot be fully diluted in rivers and other waterways.† Urbina learned that wastewater from fracking operations was about 100 tim es more toxic than federal drinking water standards; 15 wells had readings about 1,000 times higher than standards. Research by Dr. Ronald Bishop, a biochemist at SUNY/Oneonta, suggests that fracking to extract methane gas â€Å"is highly likely to degrade air, surface water and ground-water quality, to harm humans, and to negatively impact aquatic and forest ecosystems.† He notes that â€Å"potential exposure effects for humans will include poisoning of susceptible tissues, endocrine disruption syndromes, and elevated risk for certain cancers.† Every well, says Dr. Bishop, â€Å"will generate a sediment discharge of approximately eight tons per year into local waterways, further threatening federally endangered mollusks and other aquatic organisms.† In addition to the environmental pollution by the fracking process, Dr. Bishop believes â€Å"intensive use of diesel-fuel equipment will degrade air quality [that could affect] humans, livestock, and crops.† Equally important are questions about the impact of as many as 200 diesel-fueled trucks each day bringing water to t he site and then removing the waste water. In addition to the normal diesel emissions of trucks, there are also problems of leaks of the contaminated water. â€Å"We need to know how diesel fuel got into our water supply,† says Diane Siegmund, a clinical psychologist from Towanda, Pa. â€Å"It wasn’t there before the companies drilled wells; it’s here now,† she says. Siegmund is also concerned about contaminated dust and mud. â€Å"There is no oversight on these,† she says, â€Å"but those trucks are muddy when they leave the well sites, and dust may have impact miles from the well sites.† Research â€Å"strongly implicates exposure to gas drilling operations in serious health effects on humans, companion animals, livestock, horses, and wildlife,† according to Dr. Michelle Bamberger, a veterinarian, and Dr. Robert E. Oswald, a biochemist and professor of molecular medicine at Cornell University. Their study, published in New Solutions, an academic journal in environmental health, documents evidence of milk contamination, breeding problems, and cow mortality in areas near fracking operation s as higher than in areas where no fracking occurred. Drs. Bamberger and Oswald noted that some of the symptoms present in humans from what may be polluted water from fracking operations include rashes, headaches, dizziness, vomiting, and severe irritation of the eyes, nose, and throat. For animals, the symptoms often led to reproductive problems and death. Significant impact upon wildlife is also noted in a 900-page Environmental Impact Statement (EIS) conducted by New York’s Department of Environmental Conservation. According to the EIS, â€Å"In addition to loss of habitat, other potential direct impacts on wildlife from drilling in the Marcellus Shale include increased mortality . . . altered microclimates, and increased traffic, noise, lighting, and well flares.† The impact, according to the report, â€Å"may include a loss of genetic diversity, species isolation, population declines . . . increased predation, and an increase of invasive species.† The report concludes that because of fracking, there is â€Å"little to no place in the study areas where wildlife would not be impacted, [leading to] serious cascading ecological consequences.† The impact of course affects the quality of milk and meat production as animals drink and graze near areas that have been taken over by the natural gas industry. The response by the industry and its political allies to the scientific studies of the health and environmental effects of fracking â€Å"has approached the issue in a manner similar to the tobacco industry that for many years rejected the link between smoking and cancer,† say Drs. Bamberger and Oswald. Not only do they call for â€Å"full disclosure and testing of air, water, soil, animals, and humans,† but point out that with lax oversight, â€Å"the gas drilling boom . . . will remain an uncontrolled health experiment on an enormous scale.† Bibliography of Works Cited: http://www.marcellusoutreachbutler.org/ http://www.counterpunch.org/2012/03/19/the-perils-of-fracking/ www.coalitiontoprotectnewyork.org http://psehealthyenergy.net/data/Bamberger_Oswald_NS22_in_press.pdf http://www.scribd.com/doc/97449702/100-Fracking-Victims http://www.nytimes.com/2011/08/04/us/04natgas.html?pagewanted=all http://steingraber.com/ http://frack.mixplex.com/content/scientific-study-links-flammable-drinking-water-fracking http://www.hydraulicfracturing.com/Pages/information.aspx http://www.epa.gov/hydraulicfracture/ http://geology.com/articles/hydraulic-fracturing/

Tubing design

Tubing design Tubing design In the previous chapter, selection procedure of tubing diameter was based on well performance analysis. In this section, the procedure for selecting tubing material properties is presented. Selection of material is carried out by considering different forces that act on the tubing during production and workover operations and then a graphical method is used to present the tubing load against material properties. 1.1 Forces on tubing During the life of the well, tubing is subjected to various forces from production and workover operations which include: * production of hydrocarbon, * killing of the well, * squeeze cementing, * hydraulic fracturing etc. The activities result in change in temperature and pressure inside the tubing and casing-tubing annulus, which can cause a change in tubing length (shortening or lengthening). The change in length often leads to increase in compression or tension in tubing and in extreme situation unseating of packer or failure of tubing (Hammerlindl, 1977 and Lubinski et.al, 1962). According to the authors the change in pressure inside and outside of tuning and temperature can have various effects on tubing: * piston effect(According to Hookes Law), * helical buckling, * ballooning and * thermal effect. HOOKES LAW EFFECTS Changes in pressure inside and outside the tubing can cause tubing movement due to piston effect. According to Hookes law, change in length of tubing caused by this effect can be calculated using the Equation 4.1. Where is the change in forces due to the change in pressures inside ( ) and outside () tubing and can be expressed as: Where, (see Fig. 4.2) DL1= change in length due to Hookes Law effect, inch, L = length of tubing, inch, F = force acting on bottom of tubing, lb., E= modulus of elasticity, As = cross-sectional area of tubing, inch2, Ai = area based on inside diameter of tubing, inch2 and Ao = area based on outside diameter of tubing, inch2, Ap= area based on diameter of packer seal, inch2, = change in pressure inside annulus at packer (Final Initial), psi and = change in pressure inside tubing at packer (Final Initial), psi. Notes: DL, DF, DPi or DPo indicates change from initial packer setting conditions. It is assumed Pi = Po when packer is initially set. HELICAL BUCKLING The difference in pressure inside tubing and casing-tubing annulus acts on the cross sectional area of packer bore at tubing seal and leads to a decrease in the length of tubing due to buckling. This effect is known as helical buckling. When the tubing is restricted from movement, a tensile load is developed. This effect is increased with increase in inside tubing pressure. The change in length caused by helical buckling can be calculated by the Equation 4.3. where Force causing buckling: Ff = Ap (Pi Po) If Ff (a fictitious force) is zero or negative, there is no buckling. Length of tubing buckled: n = Ff / w Where, DL2= change in length due to buckling, inch, r= radial clearance between tubing and casing, inch, w = ws + wi wo, ws = weight of tubing, lb/incn, wi =weight of fluid contained inside tubing, lb/in. (density multiplied by area based on ID of tubing), wo= weight of annulus fluid displaced by bulk volume of tubing, lb/in. (density multiplied by area based on OD of tubing), =tubing outside diameter, inch and =tubing inside diameter, inch. Buckling can be avoided by applying surface annular pressure. BALLOONING EFFECTS The radial pressure inside the tubing causes tubing to increase or decrease in length. When the pressure inside the tubing is greater compared to the pressure inside the casing-tubing annulus, it tends to inflate the tubing, thus shortening the tubing. If the pressure inside the casing-tubing annulus is greater compared to pressure inside the tubing, then the tubing length is increased. This effect is known as ballooning and the change in length caused due to this effect is given by Equation 4.4. Where, DL3=change in length due to ballooning, in. m= Poissons ratio (0.3 for steel) R= tubing OD/tubing ID Dri=change in density of fluid inside tubing, lb/in3 Dro=change in density of fluid outside tubing, lb/ in3 Dpi=change in surface pressure inside tubing, psi Dpo=change in surface pressure outside tubing, psi d=pressure drop in tubing due to flow, psi/in. (usually considered as d= 0) THERMAL EFFECTS Due to the earths geothermal gradient, the temperature of the produced fluids can be high enough to change the tubing length. The effect is opposite (decrease in length) when a cold fluid is injected inside the tubing. It is ideal to take the change in average string temperature. The change in length due to temperature can be calculated using the Equation 4.5. Where, DL4=change in length, in. L=length of tubing string, in. C=coefficient of expansion of steel per oF DT=temperature change, oF PACKER SETTING FORCE The setting of packer requires forces which may lead to change in length of tubing. This change in length can be calculated using the Equation 4.6., which is derived based on Equations 4.1 and 4.3. The force on packer should not exceed critical values whereby it can cause permanent damage to the tubing. The initial weight on packer may cause slack off and to check if this situation might exist, one could use Equation 4.7. Where, F = set-down force. The tubing can suffer permanent damage if the stress in the tubing exceeds the yield strength of the tubing material. It is therefore advised to determine the safe tubing stresses for a given production or workover operation. The safe tubing stress can be calculated by using the following Equations (Allen and Roberts, 1989): The critical values can be calculated using Equations 4.8 and 4.9. Where, Si=stress at inner wall of the tubing So=stress at outer wall of the tubing For free-motion packer: When the packer exerts some force on the tubing, an additional term Ff should be added to Fa and the sign in Equations 4.8 and 4.9 varies in way to maximize the stresses. Example 4.1: An example of Tubing Movement calculation: The following operations are to be performed on a well completed with 9,000 ft of 2-7/8 OD (2.441 ID), 6.5 lb/ft tubing. The tubing is sealed with a packer which permits free motion. The packer bore is 3.25. The casing is 32 lb/ft, 7 OD (6.049 ID). Calculate the total movement of the tubing (note: notation is used for inch). Conditions Production Frac Cement Initial Fluid 12 lb/gal mud 13 lb/gal saltwater 8.5 lb/gal oil Final Fluid Tubing 10 lb/gal oil 11 lb/gal frac fluid 15 lb/gal cement Annulus 12 lb/gal mud 13 lb/gal saltwater 8.5 lb/gal oil Final Pressure Tubing 1500 psi 3500 psi 5000 psi Annulus 0 1000 psi 1000 psi Temp Change +25oF -55oF -25oF SOLUTION Production: Hookes Law Effect At bottom hole conditions DPi = Final pressure inside tubing Initial pressure inside tubing DPo = Final pressure inside annulus initial pressure inside annulus Using Eq. (4.2) Using Eq. (4.1) Helical Buckling Effect Using Eq. (4.3) Ballooning Effect Using Eq. (4.4) Temperature Effect Using Eq. (4.5) Total Tubing Movement (Tubing lengthens) Fracturing: Hookes Law Effect At bottom hole conditions DPi = Final pressure inside tubing Initial pressure inside tubing DPo = Final pressure inside annulus initial pressure inside annulus Using Eq. (4.2) Using Eq. (4.1) Helical Buckling Effect Using Eq. (4.3) Ballooning Effect Using Eq. (4.4) Temperature Effect Using Eq. (4.5) Total Tubing Movement (Tubing shortens) Cement: Hookes Law Effect At bottom hole conditions DPi = Final pressure inside tubing Initial pressure inside tubing DPo = Final pressure inside annulus initial pressure inside annulus Using Eq. (4.2) Using Eq. (4.1) Helical Buckling Effect Using Eq. (4.3) Ballooning Effect Using Eq. (4.4) Temperature Effect Using Eq. (4.5) Total Tubing Movement (Tubing shortens) 1.2 Selection of Tubing Material Tubing selection should be based on whether or not the tubing can withstand various forces which are caused due to the variations in temperature and pressure. The API has specified tubing based on the steel grade. Most common grades are: H40, J55, K55, C75, L80, N80, C95, P105 and P110. The number following the letter indicates the maximum yield strength of the material in thousands of psi. The failure of the tubing can be attributed to the loading conditions. There are three modes of tubing failure which include: * burst (pressure due to fluid inside tubing), * collapse (pressure due to fluid outside tubing) and * tension (due to weight of tubing and tension if restricted from movement). The graphical design of the tubing can be achieved by creating a plot of depth vs pressure. This design is carried out by calculating pressures inside the tubing and casing-tubing annulus at the bottom hole and tubing head. The maximum differential pressures at surface and bottom hole are examined using the plot. This maximum condition usually occurs during stimulation. When the maximum allowable annular pressure is maintained during stimulation, a considerable amount of reduction in the tubing load can be achieved. The burst pressure load (difference between the pressure inside the tubing and annulus) is mostly experienced in greater magnitude close to the surface but may not necessarily be always true. The burst load lines are plotted followed by plotting collapse load lines. The collapse loads are calculated with an assumption that a slow leak at the bottom hole has depressurized the tubing. This scenario is sometimes expereinced after the fracturing treatment when operators commence kickoff before bleeding off the annular pressure. If the data for pressure testing conditions (usually most critical load) is available, it should be included in the plot. Along with the collapse and burst loads, the burst and collapse resistance for different tubing grades (available) are plotted. By observing the plot we can determine which tubing grade to be selected that can withstand the calculated loads. An example of selecting tubing based on graphical design is presented below. Example 4.2: Graphical tubing design Based on the data given below, select a tubing string that will satisfy burst, collapse and tension with safety factors of 1.1, 1.0 and 1.8 respectively. Planning Data: D =9000 ft true depth, f = 2.875 inches, tubing OD, CIBHP = 6280psi, closed-in bottom hole pressure, FBP = 12550psi, formation breakdown pressure, FPP = 9100psi, fracture propagation pressure, Gpf = 0.4 psi / ft packer fluid gradient, Gf = .48 psi /ft fracturing fluid gradient, g = 0.75 gas gravity at reservoir, Pann = 1000 psi, maximum allowable annulus pressure, SFB =1.1, safety Factor, Burst Condition, SFC =1.0, safety Factor, Collapse Condition, SFT =1.8, safety Factor, Tensile Load, Burst and Collapse rating of available tubings: B_L80 =9395 psi, C_L80 =9920 psi, B_J55 =6453 psi, C_J55 =6826 psi, B_H40 =4693 psi and C_H40 =4960psi. Solution: Step 1: Calculate the ratio of bottomhole pressure to surface pressure. Referring table 4.1 in the manual, determine the ratio of surface and BHP at the given reservoir gas gravity, At a gas gravity = 0.8 and Depth 9000 ft, the ratio is 0.779 At a gas gravity = 0.7 and Depth 9000 ft, the ratio is 0.804 At gas gravity 0.75 the ratio of surface pressure to BHP is Table 4.1 Ratio of surface pressure and BHP in gas wells for a range of gas gravities. Depth of Hole Gas Gravity (ft) (m) 0.60 0.65 0.70 0.80 1000 305 0.979 0.978 0.976 0.973 2000 610 0.959 0.956 0.953 0.946 3000 915 0.939 0.935 0.93 0.92 4000 1219 0.92 0.914 0.907 0.895 5000 1524 0.901 0.893 0.885 0.87 6000 1830 0.883 0.873 0.854 0.847 7000 2133 0.864 0.854 0.844 0.823 8000 2438 0.847 0.835 0.823 0.801 9000 2743 0.829 0.816 0.804 0.779 10000 3048 0.812 0.798 0.764 0.758 11000 3353 0.795 0.78 0.766 0.737 12000 3660 0.779 0.763 0.747 0.717 13000 3962 0.763 0.746 0.729 0.697 14000 4267 0.747 0.729 0.712 0.678 15000 4572 0.732 0.713 0.695 0.659 16000 4876 0.717 0.697 0.67 0.641 17000 5181 0.702 0.682 0.652 0.624 18000 5486 0.687 0.656 0.645 0.607 19000 5791 0.673 0.652 0.631 0.59 20000 6097 0.659 0.637 0.615 0.574 Step 2: Calculate the pertinent pressures for different operating conditions. a) Pressures inside casing-tubing annulus Assuming during the production and killing of well, packer fluid is present inside the casing tubing annulus. For producing situation: Pressure inside annulus at surface = packer fluid gradient * Depth Pkill_prod_surface= = 0.4* 0 = 0 psi Pressure inside annulus at bottom hole = packer fluid gradient * Depth Pkill_prod = Gpf *D = 0.4* 9000 = 3600 psi For Stimulation: Pressure inside annulus at surface= Pstim_surf = 1000 psi Pressure inside annulus at bottomhole = packer fluid gradient * Depth + (Max Allowable pressure inside annulus) Pstim_bh= Gpf *D + Pann = 0.4*9000 + 1000 = 4600 psi b) Pressures inside tubing At bottom hole, pressure = CIBHP At surface, pressure = CITHP (closed in tubing head pressure) CITHP = ratio * CIBHP CITHP = 0.792 * 6280 = 4973 psi KILL SITUATION: When a well is killed, the bottom hole pressure is given as sum of CIBHP and maximum allowable annulus pressure. At bottom hole, pressure inside tubing during kill situation (BHIP) = CIBHP+Pann BHIP =6280 +1000 = 7280psi Tubing head pressure during kill situation is calculated by multiplying BHIP with gas gravity. At tubing head kill pressure (THIP) = ratio * BHIP = 0.792*7280 = 5765 psi FORMATION BREAKDOWN SITUATION: During stimulation the bottomhole pressure is the formation break down pressure and can be calculated by the density of the fracture fluid .In this problem the break down pressure is specified. At bottomhole, pressure inside tubing during formation breakdown (BHFBP) = FBP BHFBP = 12550 psi The tubing head pressure can be calculated by subtracting the hydrostatic head generated by the fracturing fluid from the bottomhole pressure. At tubing head, pressure (THFBP) = FBP -Gf* D =12550- 0.48* 9000 = 8230psi FRACTURE PROPAGATION During stimulation (propagation), we experience some pressure drop due to friction. Based on the pumping rates and properties of proppants we can determine the drop in pressure. Assuming a pressure drop of 0.35 psi / ft (usually calculated through properties of fracturing fluid and pumping rate), the bottomhole pressure at fracture propagation (BHFP) can be calculated as: DPfr = 0.35 psi/ ft At bottomhole, BHFP = FPP BHFP =9100 psi At tubing head, the pressure inside tubing can be calculated as: Tubing head fracture propagation pressure (THFP) = BHFP + DPfr* D Gf*D = 9100 + 0.35*9000 -0.48*9000 =7930 psi Step 3: Calculate the burst load for different operating conditions: Defining the burst loads: Burst Load pressure = pressure inside tubing pressure in the casing- tubing annulus Burst Load at tubing head for producing conditions: BL _surface_prod = CITHP Pkill_prod_surface = 4973 0 = 4973 psi Burst Load at bottomhole for producing conditions: BL _bh_prod = CIBHP Pkill_prod = 6280-3600 = 2680 psi Burst Load at tubing head for killing operation: BL _surface_kill = THIP Pkill_prod_surface = 5765 -0 = 5765 psi Burst Load at bottomhole for killing operation: BL _bh_kill = BHIP Pkill_prod = 7280-3600 = 3680 psi Burst Load at tubing head for formation breakdown: BL _surface_fbp = THFBP Pstim_surf = 8230 -1000 = 7230 psi Burst Load at bottomhole for formation breakdown: BL _bh_fbp = BHFBP Pstim_bh = 12550 -4600 = 7950 psi Burst Load at tubing head for fracture propagation: BL _surface_fbp = THFP Pstim_surf = 7930 -1000 = 6930 psi Burst Load at bottomhole for fracture propagation: BL _bh_fbp = BHFP Pstim_bh = 9100 -4600 = 4500 psi Step 4: Calculation of collapse Load Defining the collapse loads: Collapse load pressure = pressure in casing-tubing annulus- pressure inside tubing In order to plot critical collapse load conditions (CLL) normally, we assume that a slow leak in tubing has changed the pressure inside casing-tubing annulus to CITHP and that tubing is empty and depressurized. Step 5: Plot the Load lines. Plot the burst load and collapse load lines for various completion operations, burst and collapse resistance lines for the available tubing grades. The obtained plot is illustrated in Fig. 4.4. It can be observed from plot that formation breakdown situation has the maximum burst pressures. The maximum burst pressure line and collapse line are plotted with the available ratings of tubing. The resulting plot will look like Fig. 4.5. Then by inspecting the graph we can come to a conclusion that L-80 grade is the best grade available that can withstand the collapse and burst pressures during various operations. But in other situations we have an option to select multiple grades on tubing which are guided by the estimated loading conditions. Estimation of Tensile Load: Most of the tubing failures are caused due to coupling leakage and failure. The failure of coupling can be attributed to inadequate design for tension of the tubing. This load being one of the significant and causes most failures compared to failures due to burst and collapse pressures. A higher safety factor is used while designing tubing. The design can be initiated by considering only the weight of tubing on packer. Some companies even ignore buoyancy effects while calculating weight to have a better design. So ideally a tubing design for tension is carried out by calculating the weight of the tubing in air. Then the buoyant weight of the tubing is calculated using the densities of steel and mud. Selecting a grade of casing which can handle the tensile load generated due to the weight of the tubing. An example below illustrates the design of tubing for tension. Example 4.3 Tension Design Tubing weight: 7.2 lb/ft Tubing length: 12,500 ft Packer fluid: 0.38 psi/ft = 54.72 lb/ft3 Density of steel: 490 lb/ft3 Win_air = 7.2 x 12,500 = 90,000 lb Wbuoyant = = 0.89 x 73,600 = 80,100 lb Joint Specifications J55 L80 EUE HYD CS EUE HYD A95 API joint strength (Klb) Design factor Design capacity (Klb) 99.7 1.8 55.4 100 1.8 55.6 135.9 1.8 75.5 150 1.8 83.3 Tubing Tension Design Considerations 1. Requires L80 tubing at surface 2. Requires joint strength capability of HYD A95 or equivalent Review questions 1. When would buckling of tubing above a packer likely to occur? 2. A 10,000-ft, high-rate oil well is completed with 5ÂÂ ½ 15.5 lb/ft tubing (wall thickness 0.275). Under producing conditions the flowing temperature gradient is 0.40F/100 ft, and under static conditions the geothermal gradient is 1.8oF/100ft from a mean surface temperature of 40oF. When the well is killed with a large volume of 40oF seawater, the bottom-hole temperature drops to 70oF. If free to move, what tubing movement can be expected from the landing condition to the hot producing and to the cold injection conditions? If a hydraulic packer were to be used and set in 30,000 lb tension, what would be the tension loading on the packer after killing the well? (Ignore piston, ballooning and buckling effects). 3. A 7000-ft well that is to be produced with a target of 15,000 STB/D using 5ÂÂ ½ tubing encounters 170 ft of oil-bearing formation with a pressure of 3000 psi. What rating of wellhead should be used? If a single grade and weight tubing is to be used, what is the cheapest string that can probably be run, assuming that Grade Weight (lb/ft) Collapse Strength (psi) Burst Strength (psi) Tensional Strength (1000 lb) Cost Comparison J-55 C-75 N-80 15.5 17.0 17.0 17.0 20.0 4040 4910 6070 6280 8830 4810 5320 7250 7740 8990 300 329 423 446 524 Cheapest Most expensive Moderately expensive REFERENCES 1. Allen, TO and Roberts, AP, Well Completion Design- Production Operations-1, 3rd edition, 1989, pp 182-187. 1. Hammerlindl, DT, Movement, Forces and Stress Associated with Combination Tubing Strings Sealed with Packers, JPT, February 1977. 2. Lubinski, A, Althouse, WS, Logan, TL, Helical Buckling of Tubing Sealed in Packers, JPT, June 1962. 3. Well completion design and practices PE 301-IHRDC EP Manual Series, Boston, MA 02116, USA.

Bioterrorism Essays -- essays research papers

  Ã‚  Ã‚  Ã‚  Ã‚  You wake up early for work and kiss your family goodbye. On your daily transit you see a man drop a glass vial in the subway, but you think nothing of it. Moments later you become a statistic. A statistic of Bioterrorism. The threat of Bioterrorism, long ignored and denied has heightened over the past years and needs to be publicly addressed. There are three possible solutions to this threat that are within grasp. The first of which would be a nation wide vaccination against all agents that could be used against the American public. Second, we could educate people to more efficiently spot the symptoms of such an act, or to protect themselves from an act that has already taken place. The last solution would be to prevent the act from occurring, detect it as soon as it occurs, and destroy the destructive pathogen used. Even with all of these solutions, an act of Bioterrorism is a major threat to the United States that could occur undetected and must be dealt with im mediately in order to save lives. Biological warfare has been used from the cadavers poisoning water supplies, to modern technology allowing munitions, and advanced deployment of biological weapons. Both nations, and dissident groups exist that have some of the most dangerous, and deadly pathogens, along with the ability to deploy them. Bioterrorism presents a threat to all people of the world, and will always remain a threat for three main reasons. One, it is very easy for anyone to obtain samples of harmful agents, such as anthrax or small pox. Two, an act of this terrorism could occur at any time, any place, and there would be no reaction for days or weeks. And third, many of the agents that can be used in such acts have no treatments, let alone cures. If a group, or nation had funding and a moderate laboratory they could produce, and deploy some of the worlds deadliest pathogens undetected. For example, in 1995, the Japanese cult, Aum Shinrikyo, released the nerve gas Sarnin in the Tokyo subway. The cult also had other plans set up. In its arsenal police found large quantities of nutrient media, Botulium culture, anthrax cultures, and drone aircraft equipped with spray tanks. Members of this group have even traveled to Zaire in 1992 to obtain samples of the Ebola virus. Terrorist groups exist today that have a large quantity of diseases, chemicals, and viruses to ch... ...e need to establish a local, regional, and national disease control system. The local system would be responsible to identify the specific virus, and determine the quarantine area. Once this has been done, the regional team would come in and enforce the quarantine area, and also start a standard treatment for those patients. Once this has been done, the national team would start to determine a more specific treatment, and attempt to develop a cure. If no cure can be found, then the area shall be destroyed by any means necessary to eliminate the harmful agent, and maintain safety. If an outbreak did occur, then we shall do whatever it takes to minimize human life, without the cost of many. Bioterrorism represents a clear and present danger to the United States. Out of All the solutions I gave, if nothing is done, then it is not if an act will occur, but when it will occur. Bioterrorism has already happened, and will continue to until we do something about it. In order to do about it we must instigate a plan of nation wide vaccination, education, or prevent detect destroy. If nothing is done, then one day on your way to work you could become a statistic, a statistic of Bioterrorism.

Junot Diaz Biography

Junot Diaz was born in the Dominican Republic and raised New Jersey. He is a creative writing teacher at MIT and fiction editor at the Boston Review. He also serves on the board of advisers for the Freedom University, a Volunteer organization in Georgia that provides post-secondary instruction to undocumented immigrants. From what I have read I have gathered that he really had to rely on himself. Getting him through college working the jobs where you have to do the dirty work, dishes, and pumping-gas. Supposedly Drown reflects Diaz’s strained relationship with his own father, with whom he no longer keeps in contact with. Diaz was born in Villa Juana, a neighborhood in Santo Domingo, Dominican Republic. He was the third child in a family of five.Through most of his childhood he lived with his mother and grandparents while his father worked in the United States. Diaz emigrated to Parlin, New Jersey, in December of 1974, where he was able to reunite with his father. He lived clos e to what he considered one of the largest landfills in New Jersey. His short fiction has appeared in The New Yorker magazine, which listed him as one of the 20 top writers for the 21st century.He has also been published in Story, The Paris Review, and in the anthologies The Best American Short Stories four times (1996, 1997, 1999, 2000), The PEN/O. Henry Prize Stories (2009), and African Voices. He is best known for his two major works: the short story collection Drown (1996) and the novel The Brief Wondrous Life of Oscar Wao (2007). Both were published to critical acclaim and he won the 2008 Pulitzer Prize for Fiction for the latter. Diaz himself has described his writing style as â€Å"[†¦] a disobedient child of New Jersey and the Dominican Republic if that can be possibly imagined with way too much education.†Dà ­az has received a Eugene McDermott Award, a fellowship from the John Simon Guggenheim Memorial Foundation, a Lila Acheson Wallace Readers Digest Award, th e 2002 PEN/Malamud Award, the 2003 US-Japan Creative Artist Fellowship from the National Endowment for the Arts, a fellowship at the Radcliffe Institute for Advanced Study at Harvard University and the Rome Prize from the American Academy of Arts and Letters. He was selected as one of the 39 most important Latin American writers under the age of 39 by the Bogotà ¡ World Book Capital and the Hay Festival.[18] In September 2007, Miramax acquired the rights for a film adaptation of The Brief Wondrous Life of Oscar Wao.The stories  in Drown focus on the teenage narrator's impoverished, fatherless youth in the Dominican Republic and his struggle adapting to his new life in New Jersey. Reviews were generally strong but not without complaints. Dà ­az read twice for PRI's This American Life: â€Å"Edison, New Jersey† in 1997 and â€Å"How to Date a Browngirl, Blackgirl, Whitegirl, or Halfie† in 1998. Dà ­az also published a Spanish translation of' Drown, entitled Negocios . The arrival of his novel (The Brief Wondrous Life of Oscar Wao) in 2007 prompted a noticeable re-appraisal of Dà ­az's earlier work.Drown became widely recognized as an important landmark in contemporary literature—ten years after its initial publication—even by critics who had either entirely ignored the book or had given it poor reviews. The Brief Wondrous Life of Oscar Wao was published in September 2007. New York Times critic Michiko Kakutani characterized Dà ­az's writing in the novel as: a sort of streetwise brand of Spanglish that even the most monolingual reader can easily inhale: lots of flash words and razzle-dazzle talk, lots of body language on the sentences, lots of David Foster Wallace-esque footnotes and asides.And he conjures with seemingly effortless aplomb the two worlds his characters inhabit: the Dominican Republic, the ghost-haunted motherland that shapes their nightmares and their dreams; and America (a.k.a. New Jersey), the land of freedom an d hope and not-so-shiny possibilities that they’ve fled to as part of the great Dominican diaspora. Dà ­az said about the protagonist of the novel, â€Å"Oscar was a composite of all the nerds that I grew up with who didn’t have that special reservoir of masculine privilege. Oscar was who I would have been if it had not been for my father or my brother or my own willingness to fight or my own inability to fit into any category easily.† He also has said that he sees a meaningful and fitting connection between the science fiction and/or epic literary genres and the multi-faceted immigrant experience.

salt fluid mixture using SAFT and Molecular Dynamics. The WritePass Journal

Developing a thermodynamic equation of state for CO2/water/salt fluid mixture using SAFT and Molecular Dynamics. Previous Research Track Record Developing a thermodynamic equation of state for CO2/water/salt fluid mixture using SAFT and Molecular Dynamics. Previous Research Track RecordSome selected publications2.1 Background:   Introduction2.2  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Background:   Statistical Associating Fluid Theory (SAFT).  2.3 Research Hypothesis and Objectives2.4   Programme and MethodologyMilestones of proposed research: these are2.5   Relevance to Academic BeneficiariesReferencesRelated Previous Research Track Record Christopher Jumbo, the principal investigator in this research project, is an MSc postgraduate student of Environment and Sustainable Technology in the School of Chemical Engineering and Analytical Sciences (CEAS) at the University of Manchester. He completed his undergraduate degree programme in 2009 and holds a BSc degree (with first class distinction honours) in geology from the University of Maiduguri, Nigeria. He has worked quite appreciably in the area of sedimentary petrology. In 2008, his BSc research project dissertation saw him work on the petrographic analysis of sedimentary rocks (sandstone, shale, limestone and siltstone) mapped around the south-western extension of the Chad basin in Northeast Nigeria. This work also evaluated reservoir properties (porosity and permeability) of the basin and was supervised by Dr. Elnaffaty. A passion for environmental sustainability in the energy sector geared his research interest to modelling CO2 storage potentials in geologic reservoi rs. Receiving an award for his outstanding undergraduate performance (an MSc overseas scholarship sponsor by the Petroleum Technology development fund (PTDF) in 2010) saw him come to the University of Manchester where he now focuses in this research area. The principal co-investigator, Professor Andrew Masters, is a professor of chemical physics in CEAS at the University of Manchester. He completed his PhD in 1980 at the University of Cambridge and was post-doctoral associate between 1980 and 1984 in both Yale University and the University of Paris Sud, France respectively. Professor Masters has worked in the area of thermodynamics and statistical mechanics for 26 years and has over 90 publications accredited to him in this area. He is a Fellow of the Royal Society of Chemistry (FRSC) and a member of the molecular modelling, simulation and design research group. His research interest can broadly be categorised as the theory and modelling of soft-matters, i.e. liquids, liquid crystals, colloidal suspension, polymers and gels. The underlying thread of all his research is the ability to predict the properties of a material from knowledge about its molecular make-up. He currently is a co-investigator for a NERC grant on CO2 storage, with collaborations from Leeds, Cambridge and British Geological Society. He has supervised ten PhD students to completion and currently supervises two Post-Doctorate and five PhD students. Some selected publications [1] S. J. Halstead and A. J. Masters. Mol. Phys, 2010. 108(2): 193-203. [2] M. Dennison, A. J. Masters, D. L. Cheung, and M. P. Allen. Mol. Phys, 2009. 107: 375-382. [3] A. J. Masters. J. Phys.:Condens. Matter, 2008. 20: 1-10. [4] R. J. Dimelow and A. J. Masters. Mol. Simulation, 2007. 33: 1165-1166. [5] D. L. Cheung, L. Anton, M. P. Allen, and A. J. Masters. Computer Physics Communication, 2008. 179: 61-65. [6] A. J. Masters, X-M You, and A. Vlasov. Mol. Phys, 2005. 123: 1-7. [7] C. P. Lowe and A. J. Masters. J. Chem. Phys, 1998. 108: 183-198.       2.1 Background:   Introduction Global anthropogenic emissions of greenhouse gases (GHG), mainly CO2, from fossil fuel combustion to the atmosphere have being identified as affecting the stability of the earth’s climate. A general consensus by the Inter-governmental Panel on Climate Change (IPCC) is that the emissions and relative causes must be mitigated [IPCC, 2001]. Also, meeting the United Nations Framework Convention on Climate change (UNFCC) stabilization target, large reductions in GHG emissions is required, particularly CO2 emissions. Underground geologic storage of CO2 (from stationery emission sources) is viewed as a viable economic strategy of achieving this reduction as well as increasing the flexibility in developing alternative energy sources [Czernichowski-Lauriol et al., 2002]. CO2 injection in geologic reservoirs is employed by the petroleum industry to improve recovery rates of oil and gas in declining oil and gas fields, a process known as enhanced oil recovery (EOR) [NETL, 2010b]. The lar ge volume of saline aquifers (20% to 500% of projected CO2 emissions to 2050, Davidson et al., 2001), common occurrence and non-potential source for potable water makes storage in saline aquifers an option considered for geologic sequestration of CO2. Storage in saline aquifers can be achieved by either physical trapping (buoyant supercritical CO2), solubility trapping (Dissolution in brine), ionic (dissolved bicarbonate ion) and mineral (solid carbonate precipitate) trapping mechanisms [Czernichowski-Lauriol et al., 2002]. However, dissolution of CO2 in saline waters (solubility trapping) is considered the most important long-term retention state [Bickle, M. et al., 2007]. A key aspect of CO2 sequestration is the need to accurately predict CO2 solubility in aqueous solution at high pressures (associated with deep depth injection), over a geologic period of time. Hence a reliable equation of state is an essential ingredient for transport modelling which predicts the ultimate fate of stored CO2. Our idea is to develop a robust equation of state using the statistical associating fluid theory (SAFT) approach plus molecular dynamic simulations (using DL_POLY program) to accurately describe the thermodynamic properties and vapour-liquid equilibrium of CO2, water and salt mixtures, as this will aid in describing the solubility of CO2 in saline aquifers. 2.2  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Background:   Statistical Associating Fluid Theory (SAFT). Carbon dioxide is usually injected into saline aquifers as a supercritical fluid. Interactions between CO2, water and salt (NaCl) are a combination of associating and non-associating chain fluid mixtures. While water is a highly associating fluid [Gill-Villegas. A., et al. 1997], CO2 is considered a non-associating chain molecule and strong electrolyte solution of aqueous sodium chloride (NaCl) have being considered non-associating [Robinson, R. A., 1965]. However this only applies to ambient conditions. It has being shown that ion-ion association (ion pairing) occur in aqueous electrolyte solution as temperatures approach the critical point for water (due to the decrease in dielectric constant of water) [Pitzer, K. S. J., 1993]. Readily employed engineering equation of state, such as Peng-Robinson, Soave-Redlich-Kwong and Benedict-Webb-Rubin, are improvements on the hard sphere contribution and/or mean field term of the van der Waals equation. Their empirical approach can accurately describe the thermodynamic behaviours of simple, nearly-spherical low molecular mass hydrocarbon and simple inorganic (e.g. N2, CO, O2 etc). However the reference rapidly becomes inappropriate in predicting fluids mixtures of highly associating and non-spherical chain molecules [Economou. G.I., 2002]. This is because, for such fluids new intermolecular forces such as columbic forces, complexing forces and forces due to association comes into play which are not explicitly taking into consideration by such approach [Economou. G.I., 2002]. A more appropriate reference should incorporate the contribution of molecular shape and association as they certainly affect the fluid structure. It is in this light that Chapman et al. (in 1990) proposed an equation of state for associating chain molecules based on a series of Wertheim first-order thermodynamic perturbation expansion of Helmholtz energy [Wertheim, M. S., 1984a; 1984b; 1986a; 1986b; 1986c] called statistical associating fluid theory (SAFT). SAFT   relates the thermodynamic properties of a fluid to its intermolecular forces. In the SAFT approach, the molecular contribution to the macroscopic behaviour of the fluid is via a sum of terms which include the separate effect of the molecular shape (chain length), dispersion interaction and molecular association [Galindo, A. et al., 1998]. This consideration makes SAFT suitable for a broad range of molecules, from non-associating, near-spherical and non-spherical molecules, to associating, near-spherical and non-spherical molecules [Chapman, G. W. et al., 1990]. SAFT essentially considers complex molecules to be built-up of tangentially touching spherical monomers. The general equation for SAFT Helmholtz free energy for associating chain molecules is given by   Ã‚  Ã‚  Ã‚  Ã‚   (1) Where   is the ideal free energy,     is the excess Helmholtz energy of the free monomers,   is the Helmholtz free energy change on connecting the monomers into chains and   is the contribution to the free energy due to intermolecular association.   are the number of molecules, Boltzmann constant and temperature (K) respectively [Gill-Villegas, A. et al., 1997]. Several modification of the original Lennard-Jones (LJ) segment (used by Chapman et al.) has being made to improve the description of the monomer-monomer contribution [Banaszak, M. et al., 1993; Ghonasgi, D. Chapman, G. J., 1994; Tavares, F. W. et al., 1995]. In the modified version of SAFT (SAFT-VR) developed by Gill-Villegas and co-workers, an arbitrary potential of variable range is used to used to describe the chain molecules of hard-core segment. An additional derived parameter, the range (, allows for treatment of highly non-conformal fluid mixtures [Gill-Villegas, A. et al., 1997]. In the SAFT-VR approach, the monomer-monomer dispersion interactions are represented by second-order high-temperature perturbation expansion using a compact expression for the first order perturbation term,   (mean attractive energy). The derived second-perturbation term,  describes fluctuation of the attractive energy due to the fluid compression effect of [Gill-Villegas, A. et al., 1997]. This effect correlates to macroscopic thermodynamic compression described by local density variation of the fluid. The expression is derived from Barker and Henderson perturbation theory, and given as   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (2) Where   and   are the first and second perturbation term associated with the attractive energy of the variable range.  is the Helmholtz free energy for a mixture of hard spheres.   Ã‚  is the inverse of temperature (T in Kelvin),   and   is Boltzmann constant. When applied to mixtures SAFT-VR is simply straightforward. The mean value theorem (MVT) for pure component is still applicable in evaluating for monomer mixtures. Also the contact value and radial distribution function for pure components in mixtures can be combined obtaining similar expressions to that of pure component [Gill-Villegas, A. et al., 1997]. The equation was tested for a square well potential (SW), a Yukawa (Y) potential and a Sutherland (S) potential. Excellent representation of the vapour-liquid equilibrium (VLE) for binary mixtures of water with non-electrolytes was observed below the critical region when vapour-liquid coexistence densities were correlated with simulated results. SAFT-VR was however inadequate in describing the thermodynamic behaviour at the critical region. Galindo, A. et al., 1998, applied several mixing rule to account for the binary mixtures of non-conformal fluids using SAFT-VR, but the approach failed to adequately describe phase behaviours at the critical region. Our aim is to extend the order of thermodynamic perturbation of the monomer-monomer attractive energy term to describe the phase behaviour at the critical region. Having obtained a good description of the thermodynamic properties of water, Galindo, A. et al., 1999, extended the SAFT approach to mixtures of strong electrolyte solution (SAFT-VRE) using SW potential. Here, water molecules are modelled as hard sphere with four associating short range sites describing the hydrogen-bonding association and electrolyte molecules are modelled as two hard spheres (cation and anion) of different sizes. The mean-spherical-approximation (MSA) for the restricted primitive model was used to account for the long-range columbic ion-ion interaction. The long range water-water and ion-water attractive interaction were modelled as second-order high temperature perturbation expansion as with the SAFT-VR approach [Galindo, A. et al., 1999]. The general expression for the SAFT-VRE approach takes into consideration contributions from the ion-ion interactions and is given as   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (3) Here   is the contribution to the Helmholtz free energy from ion-ion interactions. All other terms are the same as those in equation (1). The SAFT-VRE approach can be easily extended to solutions of mixed salts as the potential parameters used are determined in terms of ions. For all studied salts (including NaCl) in a temperature range of 273-373K, the SAFT-VRE calculated vapour pressure reproduced the experimental data well. However, saturated liquid densities are slightly overestimated [Galindo, A. et al., 1999]. Our aim is to improve the VLE prediction over an increased temperature range by the addition of new terms to account for the ion-ion dispersion interaction effect. We run the DL_POLY molecular dynamics simulation package on one and two component systems using the literature potential parameters for pure CO2 molecules and aqueous NaCL salt solution mixtures respectively and validate against experiment. Once validated, simulation results can be used in addition to experimental data to validate the SAFT-VR expressions. We will also further run SAFT programme for CO2 as non-associating chain molecule using equation (1) and SAFT-VRE for mixtures of associating water molecule and two (cation and anion) associating ions using equations (3).   2.3 Research Hypothesis and Objectives We propose developing a robust thermodynamic equation of state for CO2/water/salt mixtures by using the SAFT approach and Molecular dynamics (DL_POLY) simulations. This entails improving the parameterisation of the model and including new terms to improve the thermodynamic descriptions at the critical point of the mixtures. The project takes advantage of the recent advances in modelling highly non-conformal associating chain mixtures [Gill-Villegas, A. et al., 1997], strong electrolytic mixtures [Galindo, A. et al., 1999] and simulation representation of complex fluid mixtures [Koneshan, S. et al., 2000; Lopez-Rendon, R. et al., 2008], making it feasible. Never before has the quaternary system of CO2/water/salt mixtures being modelled using a SAFT approach and the increasing need to mitigate GHG emissions (especially CO2) makes the project quite timely. The hypothesis and objectives of the various work packages (WP) are: WP1: the accurate prediction of the thermodynamics and structural properties of CO2 and aqueous solution mixtures will depend on the interaction potential model. Our objectives are to validate molecular dynamic simulation results (DL_POLY) for the various component mixtures utilising literature potentials validated against experiment. Where good matches are obtained, this will serve as a reference to improve the quality of SAFT parameters (where experimental data are lacking). WP2: the mean spherical approximation (MSA) used for the restricted primitive model (RPM) in the SAFT-VRE approach accounts exclusively for the ion-ion coulombic interaction for which electrolyte ions are assumed to be immersed in a uniform dielectric medium. Dispersive interactions between the ions, however, are lacking. Our objective is to include a new term to account for the ion-ion dispersion effect in the salt solution. WP3: in the SAFT-VR approach the monomer properties are obtained from a second-order high temperature perturbation expansion of the SW variable range potential. Our objective is to add a third-order perturbation term in powers of the square well depth () of   to improve the description of the VLE at the critical point. 2.4   Programme and Methodology WP1:  Ã‚   we will first run DL_POLY with one component system for pure water and CO2 molecules using literature interaction potentials [Lopez-Rendon, R. et al., 2008] at a given temperature and pressure range. Water will be represented as an extended simple point charge (SPC/E), as this model takes into account the polarization of water in an approximate way. Simulated results will be validated against experimental result to verify the usability of the chosen force field. Validated results for the pure components of CO2 and water will be used to run DL_POLY with binary mixture system for water-CO2, water-NaCL and water-water mixtures, utilising literature interaction potential for NaCl [Koneshan, S. et al., 2000]. Simulated results will again be tested against experimental results. If convergences occur between the vapour pressure and liquid densities the simulated result will serve as a reference to correlate the SAFT model. A molecular simulation tracks the motion of individual molecules in time and can be used to interpret experimental results or serve as substitute where no experimental data are available. Finally, we will run SAFT with one component and with binary mixture system for pure molecules of water and CO2 respectively, using literature parameters for the SAFT-VR approach (i.e. square well range, , depth, and segment diameter, , association energy,   and association volume,   ) [Galindo, A. et al., 1999; Alain, V. et al., 2004]. Where   and   , is the association energy and volume due to short range attraction between hydrogen site and oxygen electron on two different molecules. Water is modelled as a hard-sphere with four short-range non-central associating sites representing hydrogen bonding () while CO2 is modelled as tangential touching spherical dimer chain molecule (without associating sites,). These parameters are validated against experimental and/or simulation result and optimised if not well-fitted using the simplex method. This is important in describing the thermodynamic properties of real substances. WP2:  Ã‚   we will use the optimized intermolecular potentials for pure water component and run SAFT with ternary mixture system for mixtures of water in strong electrolytic solution of NaCl, utilised the extended version of SAFT-VR for strong electrolyte solution (SAFT-VRE) [Galindo, A. et al., 1999]. Water is modelled in the same spirit as SAFT-VR and contributions to Helmholtz free energy are given by equation (3). Solvent-solvent, solvent-ion and ion-ion interaction contribution will be considered  Ã‚  Ã‚  Ã‚  Ã‚   [Galindo, A. et al., 1999]. MSA assume RPM will account for the long-range coulombic interaction. However the assumption of a zero long range attractive square well ion-ion interaction will be relaxed. This has being assumed in previously modelled water-NaCl mixtures [Galindo, A. et al., 1999; Gill-Villegas, A. et al., 2000] for which equally-sized ionic molecules are solvated in a uniform dielectric solvent medium at ambient conditions. This approach has however f ailed to describe accurately thermodynamic properties at the critical point. We will be taking into account the molality of saline aquifers to relax this assumption and add a new term accounting for the ion-ion dispersion effect of the coulombic contribution to Helmholtz free energy. This is so because the effect of strong electrolytic ions on properties of highly associating polar solvent such as water can alter the critical constant of water within the critical point, leading to ion-ion association [Koneshan, S. et al., 2000]. NaCl intermolecular parameters will be taking from literature [Galindo, A. et al., 1999]. Finally, determined intermolecular parameters of the ternary mixture will fitted against experimental and/or simulated result and optimised using the simplex method. WP3:      lastly, in the SAFT-VR approach (basis for formalism in the SAFT-VRE), contribution to the Helmholtz free energy due to long-range dispersion forces is obtained via a second order high-temperature perturbation expansion of the variable range [Gill-Villegas, A. et al., 1997]. This level of approximation has excellently described thermodynamic behaviours below the critical point but fails as temperatures approach the critical point. It has being suggested that incorporating a new term due to third order perturbation in the powers of the attractive square-well depth () in the monomer-monomer segment contribution will significantly improve thermodynamic description at the critical point (recent personal communication of Masters with Galindo). This we would evaluate for mixtures of optimised ternary intermolecular SW potential parameters for water mixture in aqueous NaCl solution and previously optimised CO2 dimer molecular intermolecular parameters. It should be noted that never before has CO2/water/salt mixtures being modelled using SAFT approach and so no theoretical results are available. However the SAFT-VRE approach allows for such complex mixtures in its formalism using relatively straight forward combinations with mixing rules [Galindo, A. et al., 1999]. We will run CO2/water/salt mixtures in SAFT with quaternary system. New interaction to be considered will be CO2-water in coexisting phases. Salt will be restricted to the liquid phase (as it is assumed to be non-volatile even at high temperatures) [Parisod, C. J., 1981]. Finally, modelled results will be compared with experimental results. Knowing the Helmholtz free energy all other macroscopic thermodynamic parameters at VLE can be evaluated, hence the solubility of CO2 in saline aquifer determined. Being able to accurately predict the solubility of CO2 in saline aquifers is essential for long-term sequestration of injected CO2. Milestones of proposed research: these are M1.1:   New simulation results using DL_POLY one component and binary mixture systems for CO2/water/salt mixtures. M1.2:   Improved parameterisation of literature intermolecular potential for water and CO2 pure components using SAFT one component and binary mixture system respectively, validated against simulation results. M2.1:   Reformulation of the ion-ion coulombic interaction contribution to Helmholtz free energy to incorporate a dispersion effect between ions. M2.2:   Improved description of thermodynamic properties of water at critical point. M3.1:   Modification of SAFT-VR formalism in the monomer-monomer segment contribution to overall Helmholtz free energy and enhance predictive capability of approach within the critical point of mixtures. M3.2:   New intermolecular parameters for CO2/water/salt mixtures using SAFT with quaternary system approach validated against experimental results. 2.5   Relevance to Academic Beneficiaries One key benefit obtainable from this project is the development of an improved equation of state using statistical mechanics for CO2/water/salt mixtures. Once this improvement is attained faster and more accurate description of the mixture will be developed enhancing the prediction of CO2 solubility in saline water using theoretical models. A positive outcome will certainly interest the research community, and this will correlate directly to industries (such as the petroleum industries) performing, or intending to explore the option of, CO2 sequestration in saline aquifers. 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