Download or read book LABORATORY INVESTIGATION OF OIL COMPOSITION AFFECTING THE SUCCESS OF LOW SALINITY WATERFLOODING IN OIL WET CARBONATE ROCKS written by Gregory Kojadinovich and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved oil recovery via wettability alteration by tuning the ionic composition of the injection water has been thoroughly researched in recent years. It has been well documented that seawater can increase the water wetness of chalk at high temperature. Forced displacement and spontaneous imbibition experiments have attributed the wettability alteration to interactions between active ions in the brine, Ca2+, Mg2+, and SO42-, the rock surface, and the oil phase. It has been suggested that the adsorption of SO42- onto the rock surface causes the bond between adsorbed carboxylic material in the crude oil and the rock surface to deteriorate which causes the release of the crude oil. Reduction in ionic strength of the injection water has also been proposed to trigger the effect of wettability alteration in carbonates. Although the numerous experiments devoted to understanding the mechanisms governing the low salinity effect in the past two decades, there has been no consensus about the dominant mechanisms driving wettability alteration. The purpose of this research is to improve the understanding of how reduced ionic strength and potentially determining ions (PDIs) contribute to oil recovery, as well as provide a direct comparison of their oil recovery performance for a synthetic oil versus crude oil during waterflooding. For this, a series of waterflood experiments were conducted in the laboratory at 90 C in Indiana limestone core plugs. Chemically tuned brines derived from seawater were used in secondary and tertiary recovery modes to displace synthetic oil. A waterflood with formation brine was also conducted as an experimental baseline to assess the advantages of low-salinity waterflooding over typical secondary recovery methods. Effluent analysis was conducted to evaluate the surface interactions occurring between the brine and rock surface. Gas chromatography-mass spectroscopy was performed to compare the chemical make-up of the synthetic and crude oil. Oil recovery curves from this study indicate that there was no benefit after increasing the concentration of PDIs in injection water compared to seawater (SW). However, the use of seawater and all chemically tuned brines derived from seawater resulted in an average 6.47% increase in oil recovery post water breakthrough, relative to the formation brine waterflood. The success of wettability alteration leading to improved oil recovery in carbonates has been noted as a strong function of the oil composition.

Download or read book Laboratory Investigation of Mechanisms Governing Low salinity Waterflooding in Oil wet Carbonate Reservoirs written by Gregory Kojadinovich and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved oil recovery via wettability alteration by tuning the ionic composition of the injection water has been thoroughly researched in recent years. It has been well documented that seawater can increase the water wetness of chalk at high temperature. Forced displacement and spontaneous imbibition experiments have attributed the wettability alteration to interactions between active ions in the brine, Ca2+, Mg2+, and SO42-, the rock surface, and the oil phase. It has been suggested that the adsorption of SO42- onto the rock surface causes the bond between adsorbed carboxylic material in the crude oil and the rock surface to deteriorate which causes the release of the crude oil. Reduction in ionic strength of the injection water has also been proposed to trigger the effect of wettability alteration in carbonates. Although the numerous experiments devoted to understanding the mechanisms governing the low salinity effect in the past two decades, there has been no consensus about the dominant mechanisms driving wettability alteration. The purpose of this research is to improve the understanding of how reduced ionic strength and potentially determining ions (PDIs) contribute to oil recovery, as well as provide a direct comparison of their oil recovery performance for a synthetic oil versus crude oil during waterflooding. For this, a series of waterflood experiments were conducted in the laboratory at 90 C in Indiana limestone core plugs. Chemically tuned brines derived from seawater were used in secondary and tertiary recovery modes to displace synthetic oil. A waterflood with formation brine was also conducted as an experimental baseline to assess the advantages of low-salinity waterflooding over typical secondary recovery methods. Effluent analysis was conducted to evaluate the surface interactions occurring between the brine and rock surface. Gas chromatography-mass spectroscopy was performed to compare the chemical make-up of the synthetic and crude oil. Oil recovery curves from this study indicate that there was no benefit afterincreasing the concentration of PDIs in injection water compared to seawater (SW). However, the use of seawater and all chemically tuned brines derived from seawater resulted in an average 6.47% increase in oil recovery post water breakthrough, relative to the formation brine waterflood. The success of wettability alteration leading to improved oil recovery in carbonates has been noted as a strong function of the oil composition.

Download or read book Effect of Changing Injection Water Salinity on Oil Recovery from Oil wet Carbonate Rocks written by Ugur Pakoz and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental studies and some field applications have shown that tuning the salinity of the injected water can affect oil recovery from water flooding. Most of the available literature has dedicated efforts to investigate the effect of low salinity water injection, especially for sandstone. Further studies on carbonate rocks also proved that low salinity effect might be observed for carbonate rocks as well. The main mechanism for the improved oil recovery from low salinity water flooding has been attributed to wettability alteration. The purpose of this work is to further investigate the effect of water salinity on oil recovery from oil-wet carbonate rocks. A series of core flood experiments were performed in the laboratory to measure and compare oil recovery from increasing and decreasing salinity floods at room temperature. Selected carbonate cores were aged with synthetic oil at 100 oC for 12 days prior to core flooding. Contact angles were measured on pre-aged and post-aged core slices to validate aging procedure and oil-wet conditions. Both, increasing and decreasing salinity floods showed measurable recovery gains in the secondary and tertiary modes compared with initial floods. In case of increasing water salinity, 1.3% and 0.6% additional recoveries were obtained while in the case of decreasing water salinity, additional recoveries were 0.6% and 0.7%, all in terms of original oil in place in the core. Results suggest that the system disturbance caused by the change in injection water salinity may have a greater influence on oil recovery than wettability alteration under the laboratory conditions tested.

Download or read book An experimental and numerical study of low salinity effects on the oil recovery of carbonate limestone samples written by Felix Feldmann and published by Cuvillier Verlag. This book was released on 2020-03-02 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-salinity waterflooding is a relatively simple and cheap Enhanced oil recovery technique in which the salinity of the injected water is optimized (by desalination and/or modification) to improve oil recovery over conventional waterflooding. The presented study combines spontaneous imbibition, centrifuge method, unsteady state coreflooding and zeta potential experiments to investigate low-salinity effects in carbonate limestones samples. Compared to Formation-water and Sea-water, Diluted-sea-water caused the significantly highest spontaneous oil recovery. Moreover, the imbibition capillary pressure curves are characterized by an increasing water-wetting tendency and a residual oil saturation reduction, as the salinity of the imbibing brines decreases in comparison to Formation-water. The unsteady state corefloodings resulted in the highest secondary oil recovery when Diluted-sea-water was used as injection water. Based on the open-source C++ simulator Dumux, the study developed a numerical centrifuge and coreflooding model to history match the experimental data. The numerically derived capillary pressure and relative permeability data confirm a correlation between the system’s salinity, wettability, oil recovery and residual oil saturation.

Download or read book Low Salinity Water Flooding Application on Different Reservoir Rock Types written by mohamed magdy and published by محمد مجدي. This book was released on with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface chemistry has a great effect in enhancing oil recovery. For oil-wet sandstone reservoirs, low salinity waterflooding (LSWF) is effective as it can alter rock wettability and reduce the oil/water interfacial tension. LSWF application is related to rock’s clay content and type. Clay hydrocarbon bonding can be formed through many mechanisms such as van deer waals forces and ionic bridge. LSWF effect is to weaken these bonds through two main mechanisms, Double Layer Expansion (DLE) and Multicomponent Ionic Exchange (MIE). Two fields (S and D), in Egypt’s Western Desert, have depleted strongly oil-wet reservoirs with similar rock and fluid properties. Field (S) is flooded by low salinity water (LSW), while Field (D) is flooded by high salinity water (HSW). Fortunately, the water source for Field (S) flooding is a LSW zone, which has a salinity +/- 5000 ppm as total dissolved solids (TDS). The formation water salinity was +/- 25,000 ppm as TDS. Field (S) lab experiments showed good compatibility between injected LSW, formation water and rock minerals. XRD and SEM indicate calcareous cementation with detrital clays content around 5%. Kaolinite is the common clay type, which has a low cation exchange capacity. For Field (S), the estimated ultimate recovery (EUR) is 46%, while EUR for Field (D) is 39%. One of the main causes of this increase in Field (S) is LSWF application.

Download or read book Low Salinity and Engineered Water Injection for Sandstone and Carbonate Reservoirs written by Emad Walid Al Shalabi and published by Gulf Professional Publishing. This book was released on 2017-06-14 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low Salinity and Engineered Water Injection for Sandstone and Carbonate Reservoirs provides a first of its kind review of the low salinity and engineered water injection (LSWI/EWI) techniques for today’s more complex enhanced oil recovery methods. Reservoir engineers today are challenged in the design and physical mechanisms behind low salinity injection projects, and to date, the research is currently only located in numerous journal locations. This reference helps readers overcome these challenging issues with explanations on models, experiments, mechanism analysis, and field applications involved in low salinity and engineered water. Covering significant laboratory, numerical, and field studies, lessons learned are also highlighted along with key areas for future research in this fast-growing area of the oil and gas industry. After an introduction to its techniques, the initial chapters review the main experimental findings and explore the mechanisms behind the impact of LSWI/EWI on oil recovery. The book then moves on to the critical area of modeling and simulation, discusses the geochemistry of LSWI/EWI processes, and applications of LSWI/EWI techniques in the field, including the authors’ own recommendations based on their extensive experience. It is an essential reference for professional reservoir and field engineers, researchers and students working on LSWI/EWI and seeking to apply these methods for increased oil recovery. Teaches users how to understand the various mechanisms contributing to incremental oil recovery using low salinity and engineering water injection (LSWI/EWI) in sandstones and carbonates Balances guidance between designing laboratory experiments, to applying the LSWI/EWI techniques at both pilot-scale and full-field-scale for real-world operations Presents state-of-the-art approaches to simulation and modeling of LSWI/EWI

Download or read book Retention of Polar Oil Components in Low Salinity Water Flooding written by Yen Adams Sokama-Neuyam and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low Salinity Water Flooding (LSWF) is growing as a promising oil recovery technique for the future, especially with the focus of the petroleum industry gradually shifting to finding environmentally safe, cost effective and simple but useful oil recovery techniques. This book presents a comprehensive laboratory investigation into the influence of brine chemistry, salinity and composition on the retention of polar oil components onto reservoir rock mineral surface in relation to LSWF. During water flooding, polar oil components retains on the reservoir rock surface, partially altering the wettability of the rock. In a very simple but flowing language, I presented a comprehensive study into how brine salinity and the acid number of crude oil affects retention of these polar oil components onto the reservoir rock surface. This work is very useful for screening reservoir rocks and crude oil to select good candidates for LSWF. It presents a simple, cheaper but effective technique of selecting the optimum salinity and composition of brine required to give good results in LSWF.

Download or read book An In situ Experimental Investigation of the Interrelationship Between Wettability and Oil Recovery During Low salinity Waterflooding written by Yun Xie and published by . This book was released on 2020 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wettability reversal during the displacement processes encountered in hydrocarbon reservoirs has gained significant attention in recent years owing to its critical role in the success/failure of water-based enhanced oil recovery (EOR) schemes. Regardless of different designations used for these technologies, e.g., low-salinity waterflooding (LSWF), smart water injection, or engineered water injection, manipulating the ionic compositions and concentrations of the aqueous solutions to trigger the wettability reversal process is the shared objective. Despite the encouraging application potentials, the mechanisms that govern the wettability reversal and how it affects the displacement efficiency are still poorly understood, particularly in oil-wet carbonates. Therefore, in this work, multi-scale experiments were carefully designed and conducted to probe the impacts of rock wettability and its reversal, induced through brine chemistry manipulation, on oil recovery performance. We first investigated the adsorption-controlled calcite substrate wettability using a HPHT interfacial tension/contact angle measurement apparatus. The results were then further examined in natural rock samples through miniature core-flooding experiments. A high-resolution X-ray micro-CT scanner was used with a multiphase fluid delivery system to conduct the flow tests. Prior to each waterflooding experiment, an equilibrium wettability state was established in the core sample. This study reveals that wettability reversal, caused by adsorption/desorption of the polar components present in crude oil, is the principal factor responsible for the changes in oil recovery trend during LSWF. Dynamic contact angles measured on calcite substrates indicated that adsorption of the polar components controlled the surface wettability. Higher concentrations of Ca2+/SO42− can facilitate/obstruct the adsorption of polar components thus increase/decrease the dynamic contact angle values. A similar wetting strength sensitivity to the changes in aqueous phase composition was observed in miniature core samples when the in-situ contact angle measurement technique was used to characterize wettability. Using a dynamic aging process, weakly to strongly oil-wet conditions were established in samples aged with high-salinity brine, whereas low-salinity brine or brine with a higher concentration of sulfate ions created a more heterogeneous wettability. Different equilibrium wetting conditions thus produced various oil recovery trends. Moreover, two distinct displacement mechanisms, i.e., piston-like invasion and wetting oil layer drainage, were identified, through image analysis, to play key roles in affecting the recovery trends. Wettability reversal improved the efficiency of water-displacing-oil events by enhancing the frequency/strength of both mechanisms, while their relative contributions varied from one wettability case to another. These findings provide in-situ experimental evidence that demonstrates a direct link between the composition of the engineering injection brine and enhanced sweep efficiency at the pore scale in oil-wet carbonate samples.

Download or read book A Mechanism of Improved Oil Recovery by Low Salinity Waterflooding in Sandstone Rock written by Ramez Masoud Azmy Nasralla and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Injection of low-salinity water showed high potentials in improving oil recovery when compared to high-salinity water. However, the optimum water salinity and conditions are uncertain, due to the lack of understanding the mechanisms of fluid-rock interactions. The main objective of this study is to examine the potential and efficiency of low-salinity water in secondary and tertiary oil recovery for sandstone reservoirs. Similarly, this study aims to help in understanding the dominant mechanisms that aid in improving oil recovery by low-salinity waterflooding. Furthermore, the impact of cation type in injected brines on oil recovery was investigated. Coreflood experiments were conducted to determine the effect of water salinity and chemistry on oil recovery in the secondary and tertiary modes. The contact angle technique was used to study the impact of water salinity and composition on rock wettability. Moreover, the zeta potential at oil/brine and brine/rock interfaces was measured to explain the mechanism causing rock wettability alteration and improving oil recovery. Deionized water and different brines (from 500 to 174,000 mg/l), as well as single cation solutions were tested. Two types of crude oil with different properties and composition were used. Berea sandstone cores were utilized in the coreflood experiments. Coreflood tests indicated that injection of deionized water in the secondary mode resulted in significant oil recovery, up to 22% improvement, compared to seawater flooding. However, no more oil was recovered in the tertiary mode. In addition, injection of NaCl solution increased the oil recovery compared to injection of CaCl2 or MgCl2 at the same concentration. Contact angle results demonstrated that low-salinity water has an impact on the rock wettability; the more reduction in water salinity, the more a water-wet rock surface is produced. In addition, NaCl solutions made the rock more water-wet compared to CaCl2 or MgCl2 at the same concentration. Low-salinity water and NaCl solutions showed a highly negative charge at rock/brine and oil/brine interfaces by zeta potential measurements, which results in greater repulsive forces between the oil and rock surface. This leads to double-layer expansion and water-wet systems. These results demonstrate that the double-layer expansion is a primary mechanism of improving oil recovery when water chemical composition is manipulated. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149468

Download or read book Modeling of Temperature Effect on Low Salinity Waterflooding written by Wensi Fu and published by . This book was released on 2016 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent studies have shown that additional oil can be achieved by modifying the composition and/or salinity of the injection water. Low salinity waterflooding gains popularity due to its low cost, availability of water, and high displacement efficiency of light to medium gravity oil. Various mechanisms behind low salinity waterflooding have been proposed. However, the dominant underlying mechanism is still under debate due to the complex nature of the interaction between crude oil/brine/rock (COBR). Temperature has been reported to play a significant role in the process of low salinity waterflooding, particularly in carbonates. Temperature may affect geochemical reactions between rock surface, crude oil, and water and consequently alter the rock wettability. Investigating the temperature effect not only helps identify optimum condition to achieve additional oil recovery but also contributes to understanding the mechanisms behind low salinity waterflooding. In order to investigate the temperature effect on low salinity waterflooding, we implemented an energy module in the UTCOMP-IPhreeqc simulator. Hereafter, we refer to the improved simulator as “non-isothermal UTCOMP-IPhreeqc.” UTCOMP-IPhreeqc is capable of modeling non-isothermal, multi-dimensional, and multi-phase transport process with geochemical calculations between water, minerals, gases, ion exchangers, kinetics, and surface complexes. Non-isothermal UTCOMP-IPhreeqc was then applied to study the temperature effect on low salinity coreflood experiments of sandstone and carbonate rocks based on the laboratory work of Kozaki (2012) and Chandrasekhar (2013), respectively. Our simulation results revealed that for the sandstone case, changing the temperature from 30 to 120 oC has insignificant effect on the oil recovery. We believe the reason is due to the fact that for this specific case the total ionic strength and the viscosity ratio (water viscosity over oil viscosity) did not change with increasing temperature. Noteworthy, double-layer expansion is assumed to be the underlying mechanism for low salinity waterflooding in sandstones in non-isothermal UTCOMP-IPhreeqc. On the other hand, the total ionic strength is the main controlling parameter for the double-layer expansion. For the carbonate case, with increasing temperature from 120 to 150 oC, oil recovery increased for both formation brine and low salinity water injection. The reason: while the viscosity ratio remained constant, calcite dissolution increases as the temperature increases. The calcite dissolution is assumed to be the underlying mechanism for low salinity water in carbonates in non-isothermal UTCOMP-IPhreeqc. Hence, as more calcite dissolves the wettability of the rock changes towards more water-wet. As a result, oil recovery improves.

Download or read book Waterflooding written by G. Paul Willhite and published by . This book was released on 1986 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waterflooding begins with understanding the basic principles of immiscible displacement, then presents a systematic procedure for designing a waterflood.

Download or read book Hybrid Enhanced Oil Recovery Using Smart Waterflooding written by Kun Sang Lee and published by Gulf Professional Publishing. This book was released on 2019-04-03 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hybrid Enhanced Oil Recovery Using Smart Waterflooding explains the latest technologies used in the integration of low-salinity and smart waterflooding in other EOR processes to reduce risks attributed to numerous difficulties in existing technologies, also introducing the synergetic effects. Covering both lab and field work and the challenges ahead, the book delivers a cutting-edge product for today’s reservoir engineers. Explains how smart waterflooding is beneficial to each EOR process, such as miscible, chemical and thermal technologies Discusses the mechanics and modeling involved using geochemistry Provides extensive tools, such as reservoir simulations through experiments and field tests, establishing a bridge between theory and practice

Download or read book Core Analysis written by Colin McPhee and published by Elsevier. This book was released on 2015-12-10 with total page 853 pages. Available in PDF, EPUB and Kindle. Book excerpt: Core Analysis: A Best Practice Guide is a practical guide to the design of core analysis programs. Written to address the need for an updated set of recommended practices covering special core analysis and geomechanics tests, the book also provides unique insights into data quality control diagnosis and data utilization in reservoir models. The book's best practices and procedures benefit petrophysicists, geoscientists, reservoir engineers, and production engineers, who will find useful information on core data in reservoir static and dynamic models. It provides a solid understanding of the core analysis procedures and methods used by commercial laboratories, the details of lab data reporting required to create quality control tests, and the diagnostic plots and protocols that can be used to identify suspect or erroneous data. Provides a practical overview of core analysis, from coring at the well site to laboratory data acquisition and interpretation Defines current best practice in core analysis preparation and test procedures, and the diagnostic tools used to quality control core data Provides essential information on design of core analysis programs and to judge the quality and reliability of core analysis data ultimately used in reservoir evaluation Of specific interest to those working in core analysis, porosity, relative permeability, and geomechanics

Download or read book A Sensitivity Study on Modified Salinity Waterflooding and Its Hybrid Processes written by Beibit Bissakayev and published by . This book was released on 2016 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waterflood is one of the most widely used techniques in enhanced oil recovery. In 1990s researchers came to conclusion that the chemistry of the injected water can be important in improving oil recovery. The low salinity water injection (LoSal® ) has become one of the promising topics in the oil industry. It is believed that the main mechanism for incremental oil recovery in low salinity flooding is wettability alteration. Several papers discussed that the wettability alteration from oil-wet to mixed- or water-wet takes place due to clay swelling and expanding of double layer in sandstones and calcite dissolution along with rock surface reactions in carbonates. However, there is no consensus on a single main mechanism for the low salinity effect on oil recovery. The main objective of this research is to conduct sensitivity analysis on main parameters in low salinity waterflooding and its hybrid processes affecting oil recovery in carbonates. We compare results by using coupled reservoir simulator UTCOMP-IPhreeqc. UTCOMP is the compositional reservoir simulator developed at the Center for Petroleum and Geosystems Engineering in The University of Texas at Austin. IPhreeqc is the module-based version of the PHREEQC geochemical package, a state-of-the-art geochemical package developed by the United States Geological Survey (USGS). We investigate the effect of low salinity water and carbon dioxide on oil recovery from carbonates by modeling the processes through the UTCOMP-IPhreeqc simulator. We perform sensitivity analysis on continuous gas injection (CGI), water-alternating-gas (WAG) flooding, and polymer-water-alternate-water (PWAG) flooding. We study the significance of reservoir parameters, such as reservoir heterogeneity (Dykstra-Parsons coefficient, Vdp, and crossflow, kv/kh), the salinity of injected water, the composition of gas, and polymer concentration in polymer-water solution on cumulative oil recovery. Moreover, we study the importance of inclusion of the hydrocarbon CO2 impact on the aqueous-rock geochemistry by comparing two scenarios where in one scenario the hydrocarbon CO2 effect is included in UTCOMP-IPhreeqc whereas in the other one the effect is neglected. Finally, we perform sensitivity analysis on PWAG flooding for most influential design parameters using Design of Expert software. The reservoir parameters, such as average reservoir permeability, reservoir heterogeneity, and crossflow and injected polymer-water solution parameters, such as polymer concentration and salinity of injected water are optimization parameters in this study.

Download or read book Chemical Methods written by Abdolhossein Hemmati-Sarapardeh and published by Gulf Professional Publishing. This book was released on 2021-11-30 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical Methods, a new release in the Enhanced Oil Recovery series, helps engineers focus on the latest developments in one fast-growing area. Different techniques are described in addition to the latest technologies in data mining and hybrid processes. Beginning with an introduction to chemical concepts and polymer flooding, the book then focuses on more complex content, guiding readers into newer topics involving smart water injection and ionic liquids for EOR. Supported field case studies illustrate a bridge between research and practical application, thus making the book useful for academics and practicing engineers. This series delivers a multi-volume approach that addresses the latest research on various types of EOR. Supported by a full spectrum of contributors, this book gives petroleum engineers and researchers the latest developments and field applications to drive innovation for the future of energy. Presents the latest research and practical applications specific to chemical enhanced oil recovery methods Helps users understand new research on available technology, including chemical flooding specific to unconventional reservoirs and hybrid chemical options Includes additional methods, such as data mining applications and economic and environmental considerations

Download or read book Experimental Insight Into Chemically Tuned Waterflooding in Oil wet Carbonate Reservoirs written by Prakash Purswani and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Brine composition is known to affect the effectiveness of waterflooding during enhanced oil recovery from oilwet carbonate reservoirs. Salinity, pH and ion composition of the injecting brine have been identified as important factors toward altering the wettability of the carbonate rocks to a more waterwet system. In particular, the importance of Mg2+, Ca2+, and SO42- ions have been identified as critical for incremental oil recovery via wettability alteration. To further explore the chemical mechanism of wettability alteration and to evaluate the individual contribution of these ions toward improving oil recovery, a series of waterflood experiments with different ionic composition was performed at 90oC. Characterization techniques like Zeta potential, contact angle, and trace element analysis were performed to evaluate the surface interactions taking place among the rock, the brine solution, and the crude oil. Zeta potential measurements highlight the affinity of Mg2+, Ca2+, and SO42- ions toward the rock surface in chemically tuned brines, where, an increase in the magnitude of Zeta potential was observed corresponding to the increase in the concentration of each of these ions in the suspension. Oil recovery measurements show an increase for all chemically tuned brines, when compared to recoveries obtained from plain seawater injection. Relative permeability estimations and contact angle measurements show corresponding trends of increasing waterwetness. Maximum recovery of ~76% original oil in place (OOIP) was observed for the brine with increased Mg2+ ion concentration due to higher activity of Mg2+ ions and their ability to replace Ca2+ ions from the rock surface. A lower recovery of ~64% OOIP was seen for the brine with increased Ca2+ ion concentration due to lower activity of Ca2+ ions as opposed to Mg2+ ions. Further lower recovery of ~59% OOIP was seen for the brine with increased SO42- ion concentration due to the precipitation of these ions on the rock surface. These surface reactions including salt precipitation, crude oil desorption, and rock dissolution were confirmed through the ionic analysis of the effluent brine during each waterflooding experiment. These results help clarify the importance of chemical tuning of brines toward improving oil recovery and provide experimental insight into the chemical mechanism of wettability alteration.

Download or read book Novel Insights Into Low Salinity Water Flooding Enhanced Oil Recovery in Sandstone Reservoirs written by Hasan N. Al-Saedi and published by . This book was released on 2019 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Ever growing global energy demand and the natural decline in oil production from mature oil fields have been the main incentives to search for methods to increase recovery efficiency for several decades. Water flooding is extensively applied worldwide to improve oil recovery. The recent drop in oil prices has turned the oil industry to the cheapest improved oil recovery (IOR) techniques, such as low salinity (LS) waterflooding. Also, the reduction in reservoir energy and the friendly environmental aspects of low salinity water flooding (LSWF) provide additional incentives for its use. That LS water requires decreasing only the active divalent cations such as Ca2+, Mg2+ and water salinity makes LS water flooding a relatively simple and low expense IOR technique. The water chemistry significantly impacts the oil recovery factor. Wettability is one of the major parameters that control the efficiency of water flooding. The primary mechanism for increased oil recovery during LSWF in both sandstone and carbonate reservoirs is wettability alteration of the rock surface from oil-wet to water-wet. LS water imbibed into the low water-wet zones, the water wetness of the rock increased after injecting LS water, and in turn, microscopic sweep efficiency enhanced too. The mechanism behind LS water flooding has been extensively investigated in the literature but it still a topic of debate. The objective of this research is to solve the controversy and show the following: (1) Water chemistry weather partially or strongly determines the dominant wettability alteration mode. (2) The role of divalent cations in the formation water and in the injected water. (3) Clay's role for incremental recovery. This research work seeks to quantify the effects of mineral composition and water chemistry on water-rock interactions and wettability alteration"--Abstract, page