Predicting effects of wettability variations on displacement behavior and their incorporation into inflow performance

Wettability plays a crucial role in reservoir fluid dynamics. Wettability controls the initial fluid distribution, fluid movement, further displacement of one fluid by another and hence effecting recovery from a reservoir. Wettability also has strong influence on capillary pressure and relative permeability. During different stages of reservoir development and depletion, this phenomenon becomes further complex, when wettability changes with the passage of time as a result of undergoing several processes. To-date, correlations are available for re-generating the laboratory data for capillary pressure curves, but there is still an immense need of set of correlations which can predict the capillary pressure curve behavior at any prevailing wettability conditions, when its behavior at any wettability is known. Keeping it in view, effective saturation correlation is modified and a set of correlations have been developed which can generate capillary pressure data at any prevailing wettability condition. Furthermore, the methodology for generating the corresponding relative permeability data at any wettability condition has been formulated. In order to use it in a time efficient manner, state-of-the-art system, comprising of suite of softwares have been designed, which is capable of generating capillary pressure and relative permeability curves, efficiently. In addition, the developed system is also capable of performing tubing flow calculations, providing real time monitoring and analyzing of subsurface production systems. The developed set of correlations and the suite of softwares, in conjunction with reservoir simulator, Eclipse 100, collectively named as state-of-the-art Subsurface Flow System Optimizer and Designer have been used for simulation studies of conventional and naturally fractured reservoir. The obtained results show improved history match and hence resulting into improved forecast and decision making, as a result of better understanding of wettability variations effect on displacement behavior and their incorporation into Subsurface Flow System Optimizer and Designer

PREDICTIVE MODELING USING CAPILLARY PRESSURE MODELS AND FLUID DENSITIES AND THEIR EFFECT ON RESERVOIR FLUID DISTRIBUTION AND DYNAMICS

Capillary pressure has always been a point of concern for reservoir modeling. It describes the initial pressure at which the de-saturation will be initiated and at the other extreme; it defines the irreducible saturation of the displaced fluid. In this study, Brooks & Corey and Van Genuchten models are used to predict maximum displacement pressure data with reference to non-uniformity in pore-size distribution. Both models are compared and a correlation has been developed to predict maximum displacement pressure with reference to variation in pore-size distribution index for Van Genuchten model. Further, the fluid distribution and water-oil contact level with reference to free-water level has been calculated using both models for reservoir modeling. The obtained results show that Van Genuchten model gives higher thickness for transition zones and difference in water-oil contact level with reference to free water level, as compared to Brooks and Corey correlation. Furthermore, on comparative basis, these differences increase with the decrease in uniformity in pore size distribution. Thus, the degree of uncertainty and complexity in developing reservoirs and analyzing fluid dynamics increases, in case of tighter or heterogeneous formations. Further, this study also shows that density also plays an important role in fluid dynamics and distribution with the reservoir

State-of-the-art software for K & N correlation to generate capillary pressure curves under different wettability conditions

Uzorci jezgre dobiveni bušenjem obično nisu pravi pokazatelj stanja ležišta zbog prodora filtrata isplake. Prodor može izazvati promjene močivosti, što utječe na kapilarni tlak. Kako bi se dobili podaci o kapilarnome tlaku koji je stvaran pokazatelj ležišta, razvijen je set korelacija uz čiju se primjenu mogu generirati krivulje pri bilo kojoj močivosti ako su poznati laboratorijski podaci za svaki uvjet močivosti. Da bi se olakšala uporaba razvijenoga seta korelacija razvijen je i software koji se koristi posljednjim dostignućima programiranja u Visual Basicu.Core samples obtained while drilling are usually not true representative of the reservoir due to invasion of mud filtrate. Invasion can lead to wettability alterations affecting the capillary pressure. So to have a capillary pressure data which is true representative of the reservoir, set of correlations has been developed, capable of generating the curves at any wettability, when the laboratory data at any wettability condition(s) is known. To ease the use of developed set of correlations, software has also been developed by accomplishing state-of-the-art programming in Visual Basic

Wettability – Interpreting the Myth

Močivost igra važnu ulogu u početnoj distribuciji fluida, gibanju fluida, kao i pri istiskivanju jednog fluida drugim fluidom unutar ležišta. Močivost ležišta može se kretati u rasponu od ekstremno hidrofilnog do ekstremno hidrofobnog. U času otkrića ležišta močivost u pojedinim dijelovima može biti različita i može se mijenjati tijekom vremena. Da bismo pravilno shvatili ponašanje procesa istiskivanja nafte vrlo je važno razumjeti koji tip močivosti djeluje u ležištu kako bismo optimizirali nadzor ležišta.Wettability plays a significant role in the initial distribution of fluids, movement of fluids and as well as the displacement of one fluid by another, within the reservoir. Reservoirs wettability can range from extremely water-wet to extremely oil-wet. Wettability might be different in different parts of the reservoir at the time of discovery and can even change with the passage of time. So to properly understand the displacement behavior within the reservoir proper understanding of the type of wettability existing within a reservoir is very important, for optimized reservoir surveillance

State-of-the-art software for K & N correlation to generate capillary pressure curves under different wettability conditions

Uzorci jezgre dobiveni bušenjem obično nisu pravi pokazatelj stanja ležišta zbog prodora filtrata isplake. Prodor može izazvati promjene močivosti, što utječe na kapilarni tlak. Kako bi se dobili podaci o kapilarnome tlaku koji je stvaran pokazatelj ležišta, razvijen je set korelacija uz čiju se primjenu mogu generirati krivulje pri bilo kojoj močivosti ako su poznati laboratorijski podaci za svaki uvjet močivosti. Da bi se olakšala uporaba razvijenoga seta korelacija razvijen je i software koji se koristi posljednjim dostignućima programiranja u Visual Basicu.Core samples obtained while drilling are usually not true representative of the reservoir due to invasion of mud filtrate. Invasion can lead to wettability alterations affecting the capillary pressure. So to have a capillary pressure data which is true representative of the reservoir, set of correlations has been developed, capable of generating the curves at any wettability, when the laboratory data at any wettability condition(s) is known. To ease the use of developed set of correlations, software has also been developed by accomplishing state-of-the-art programming in Visual Basic

Implementation of Brooks and Corey Correlation in Water Wet Case -With Immobile Wetting Phase

Brooks i Corey1 razvili su korelaciju za procjenu kapilarnog tlaka za procese dreniranja koja koristi koncept efektivnog zasićenja za generiranje podataka. Ovo efektivno zasićenje u korelaciji, izračunato je primarno na osnovu promjene u zasićenju faze vlaženja, može se prilično učinkovito koristiti za odgovarajuće svrhe. Međutim, postoje slučajevi u kojima zasićenje močive faze ostaje konstantno kroz cijeli proces istiskivanja. Za takve slučaje načinjena je modifikacija radi boljega prikaza i korištenja korelacije Brooksa i Coreya za procjenu kapilarnog tlaka. Ova modifikacija rezultira boljim analizama, koje pak omogućuju bolje upravljanje i nadgledanje ležišta.Brooks and Corey1 developed a correlation to estimate the capillary pressure for drainage processes, which utilizes the concept of effective saturation to generate data. This effective saturation in the correlation is calculated, primarily based on the change in wetting phase saturation and can be used quite effectively for the respective purposes. However, there are cases, in which the wetting phase saturation remains constant throughout the displacement process. For such cases, a modification has been made for better representation and to use Brooks and Corey correlation for capillary pressure estimation under such cases. This modification will result into better analysis, which will result into better reservoir monitoring and surveillance

Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial

Prediction and estimation of capillary pressure of wettability and wettability variations within reservoir

Wettability is defined as a property of a fluid to coat a rock surface, but unfortunately it is not as simple as the name implies. Formation can be oil-wet, water-wet or of mixed wettability. These variations are due to the initial water saturation, composition of oil, salt contents in brine and mineralogy of the formation. Wettability and wettability variations affect the displacement behavior of one fluid by another. This can be demonstrated by a number of experiments, using same core, where the trend of capillary pressure curve changes with reference to changes in saturation. In relation to it, several correlations have been developed to estimate the capillary pressure as a function of saturation based on experiments. In reality different types of wettability can exist in different regions of reservoir and moreover wettability existing at the time of discovery changes with the passage of time as a result of different processes for example, depletion, gas injection. To account for such variations and for proper understanding of displacement behavior within a reservoir a correlation has been developed, which can he used successfully for better reservoir surveillance. With the help of this correlation, if at least one capillary pressure curve is available, it is possible to estimate/predict the capillary pressure under different wettability conditions, which can exist within the reservoir, during different stages of depletion, with the help of which proper history matching, forecasting and hence proper selection of enhanced recovery method is possible, resulting in better decision making and increased profitability