Dr. Himanshu Sharma's Talk

Oct 04, 2018 - 17:00

Oct 04, 2018 - 18:00

Room 118 Chemical Engg Dept

Seminars

Dr. Himanshu Sharma University of Texas at Austin

Abstract: Wettability of oil reservoirs plays an important role in determining how different phases flow through it. This in-turn significantly affects the oil recovery process. Carbonate reservoirs hold the majority of the world’s oil reserves. These reservoirs are often oil-wet and thus respond poorly to water flooding. Many of these reservoirs are also fractured which hurt the oil recovery even more because the injected water bypasses through fractures and does not imbibe into the matrix. The recovery from these reservoirs can be increased substantially through wettability alteration. Wettability alteration results in increasing the relative permeability of oil and imbibition of water into the matrix from fractures. Injection of low salinity brines with carefully modified ionic compositions has shown to alter the wettability of oil-wet carbonate rocks at high temperatures and thus increase the oil recovery. The brines include seawater seawater with higher sulfate concentrations diluted seawater and so on. It has been observed that potential determining ions (calcium magnesium and sulfate) present in these brines are critical for wettability alteration. Although lab studies have shown additional oil recovery from carbonate rocks on injecting low salinity brines the mechanisms responsible for the wettability alteration process are not clear. As a result there is currently no realistic model that can be used for simulating lab results screening out potential reservoir candidates and making field predictions. In our study we conducted a systematic study to understand the mechanisms responsible for the wettability alteration. Single phase static and dynamic experiments were performed to understand interactions of low salinity brines in carbonate rocks at high temperatures. Oil recovery corefloods were performed to study the effect of brine composition on oil recovery. A multiphase multicomponent reactive flow reservoir simulator was developed. Based on the lab results a mechanistic model for the wettability alteration process was developed and implemented in the reservoir simulator and single phase and oil recovery lab experiments were modeled. The model assumes that attachment of naphthenic acids (from oil) on the rock surface under high salinity and high temperature environment results in making the rock oil-wet. In the presence of specific ions present in low salinity brines these interactions become weak and acids are released from the surface thus making the rock water-wet. The experiments showed incremental oil production from oil-wet carbonate rocks on injecting low salinity brines. Sulfate adsorption dolomitization and calcite dissolution were found to be the key geochemical reactions in this process. Among these reactions sulfate adsorption and dolomitization reactions were dominant. The extent of calcite dissolution was small even when diluted seawater was injected. Unlike other existing models our model was able to successfully capture these interactions under different circumstances and showed good agreement with single phase and oil recovery lab results. Furthermore the model was successfully able to simulate other lab results reported in the literature.Bio: Himanshu Sharma is currently a postdoctoral fellow in the department of petroleum engineering at the University of Texas at Austin. He has a PhD in petroleum engineering from UT Austin and a dual degree in chemical engineering from IIT Kharagpur. His research interests are broadly in the areas of interfacial science and reactive transport in porous media. His current research focus is on developing chemical and gas based enhanced oil recovery techniques for sandstone and carbonate reservoirs. He has published more than twenty journal and conference articles and submitted four US patent applications. He has previously held two research positions in the industry and various teaching and mentoring positions at UT Austin. This seminar is compulsory for students registered for course CL 702 or CL 704.