Determination of water breakthrough time in noncommunicating layered reservoir

The original Buckley-Leverett fractional flow formula has been extended and more detailed formulation of waterflooding behaviour in a multilayered system is presented. In this paper, the layers are assumed to communicate only in the wellbores, and the reservoir maybe represented as linear system. Most previous investigations of this nature were limited by assumptions. This study improves on previous work by applying Buckley-Laverett displacement theory to a noncommunicating layered reservoir where permeability, porosity and thickness vary from layer to layer except the oil-water relative permeability and oil viscosity are assumed the same for all layers. Gravity and capillary pressure effects are neglected. These particular considerations have been given to the evaluation of breakthrough time for each layer as a function of cumulative water injection into that layer at the breakthrough. To verify the modified method, calculations were performed a three layered reservoir at three different cases of mobility ratios and compared with Prats et al's method. It is shown that the breakthrough times in the layer with lowest permeability-thickness product (kh) are in very good agreement with Prats et al's method. However, breakthrough times for the layer with the highest kh are slightly different from Prats et al's method

Water saturation estimation in tight shaly gas sandstones by application of Progressive Quasi-Static (PQS) algorithm - a case study

Prediction of formation water saturation can be achieved through capillary pressure data in saturation-height modeling. The LSMPQS (Level Set Method Progressive Quasi Static) method is the newest numerical simulation which is basically utilized for determining critical curvatures for drainage and imbibitions curves; consequently it can be used for studies on saturation history. Thus, the amounts of water saturations were obtained by drainage simulation in saturation-height modeling.The saturation results from Indonesian model that is the best traditional log-derived saturation model in tight shaly sandstones were compared with this simulation results. It is concluded that there is a good match between log derived and simulation results. The simulation results show that it can be used as a tool for prediction of water saturation only with knowing the geometry of sedimentary environment in pore scale

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

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

Effects of grain size and grain geometries on residual oil saturation after water flooding

This paper presents an experimental study on the effect of grains size and grain geometry on residual oil saturation after water flooding. Cylindrical sand pack holder (2.5 cm × 30.5 cm) was developed and all variables except grain size and grain geometry were kept constant during the water flood experiment. The flow rates of water flooding process in this experiment were set to 11 ml/min, crude oil as a displaced fluid and NaCl solution (brine) with 20,000 ppm concentration was used as a displacing fluid injected into the sand pack. The result from the first part of the experiment revealed that grain with size from 250 – 500 (μm) produce the highest residual oil saturation, while grain with 1000-2000 (μm) size recovers more oil. Second part of the study show that angular grain geometry with (80% glass bead + 20% sand) produced the highest residual oil saturation, indicating an effect on residual oil saturation due to grain geometry, while percentage of oil recovery varies when there is an increase of percentage of sand in sand pack consist of glass bead. The result of this study showed that grain size and grain geometry have a measurable effect on residual oil saturation after water flooding

Investigation of water breakthrough time in non-communicating layered reservoir

The original Buckley-Leverett fractional flow formula has been extended and more detailed formulation of waterflooding behavior in a multilayered system is presented. In this paper, the layers are assumed to communicate only in the wellbores, and the reservoir may be represented as linear system. Most previous investigations of this nature were limited by assumptions. This study improves on previous work by applying Buckley-Leverett displacement theory to a noncommunicating layered reservoir where permeability, porosity and thickness vary from layer to layer except the oil-water relative permeability and oil viscosity are assumed the same for all layers. Gravity and capillary pressure effects are neglected. These particular considerations have been given to the evaluation of breakthrough time for each layer as a function of cumulative water injection into that layer at the breakthrough. To verify the modified method, calculations were performed a three layered reservoir for three different cases of mobility ratios, then compared with Prats et al’s method. It is shown that the breakthrough times in the layer with the lowest permeability-thickness product (kh) are in very good agreement with Prats et al’s method. However, breakthrough times for the layer with the highest kh are slightly different from Prats et al’s metho

Wettability effects on oil displacement behaviour

This paper discusses the wettability of reservoir rocks and how it effects oil recovery by displacements processes