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Rohilla N.,Nalco Company | Carlisle C.T.,Chemical Tracers Inc. | Jones N.,University of Wyoming | Davis M.B.,Sunshine Valley Petroleum Corporation | Finch K.B.H.,Nalco Company
Proceedings - SPE Symposium on Improved Oil Recovery | Year: 2016

Sandstone reservoirs containing significant amount of clays (30-40 wt%) with moderate permeability (20-50 mD) provide a unique challenge to surfactant based enhanced oil recovery (EOR) processes. A critical risk factor for these types of reservoirs is adsorption of surfactants due to greater surface area attributed to clays. Clays also have high cation exchange capacity (CEC) and can release significant amounts of di-valents that lead to increased retention of the surfactant. These factors could adversely affect the economics of a flood. We present a case study where a robust formulation was designed and tested in lab/field for a reservoir located in Wyoming, USA and contains up to 35-40 wt% clays (predominately Kaolinite and Illite). The residual oil saturation is high (Sor=0.4) while the permeability of the formation is between 20-50 mD. The reservoir has been waterflooded historically with low salinity water which has led to formation permeability damage. Due to high levels of clays, adsorption of the surfactant on the rock surface was determined to be between 3-4 mg/g rock by static adsorption tests. This publication demonstrates how the following challenges have been successfully addressed in the lab as well as in the field in the form of single well chemical tracer test (SWCTT). Copyright 2016, Society of Petroleum Engineers. Source


Carlisle C.,Chemical Tracers Inc. | Al-Saad B.,Kuwait Oil Company | Pope G.,University of Texas at Austin
Proceedings - SPE Symposium on Improved Oil Recovery | Year: 2014

Kuwait Oil Company has recognized the implications of the recent technological advances that are very likely to transform the oil industry and make chemical enhanced oil recovery methods such as alkaline-surfactant-polymer (ASP) flooding a hallmark of enhanced oil recovery. An ambitious program to apply chemical EOR to both sandstone and carbonate oil reservoirs , Kuwait is already underway. In this paper, we present the first field results of this effort. First we discuss the approach used to design a novel surfactant formulation for a high-salinity, high-temperature, highly heterogeneous carbonate reservoir, the Sabriyah-Mauddud , Kuwait,and the evaluation of the ASP process in three one-spot ASP pilots (i.e., three two-stage single well chemical tracer tests). We summarize the results of the surfactant laboratory experiments used to select the final ASP formulation and we present detailed results and interpretation of the subsequent single-well chemical tracer test (SWCTTs) results using ASP chemicals as well as details of the field operation including quality control measurements performed in the field lab. The residual oil saturations measured before and after the injection of the ASP slug and polymer drives clearly show that the chemical solution was effective in mobilizing and displacing residual oil saturation following injection of water. The injectivity of high molecular weight polyacrylamide polymer was excellent despite the low permeability of the formation. Copyright 2014 , Society of Petroleum Engineers. Source


DeZabala E.,Hess Corporation | Parekh B.,Hess Corporation | Solis H.,Hess Corporation | Choudhary M.,Hess Corporation | And 2 more authors.
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2011

Remaining oil saturation (ROS) and waterflood residual oil saturation (S orw) are key parameters for reservoir modeling and waterflood management in a group of heterogeneous deepwater turbidite reservoirs. A large amount of laboratory special core analysis (SCAL) data indicated high S orw values and a large target potential target for chemical EOR (enhanced oil recovery). Available SCAL data was not considered reliable. Acquiring additional core was considered to be too costly and too risky due to the highly deviated well paths required for new wells. Single Well Chemical Tracer Tests (SWCTT's) in producing wells were the only viable alternative. This paper describes - to our knowledge - the first applications of SWCTT in a deepwater setting. An early 2010 SWCTT showed ROS / S orw to be much lower than expected but test interpretation was uncertain. The 1 st SWCTT provided a valuable learning experience to improve test design and execution and to improve on significant logistical challenges in the deepwater setting. Using lessons learned we performed two additional SWCTT's in late 2010. The later SWCTT's included well integrity pre-tests and smaller completion intervals. Typical SWCTT volumes were ∼5,000 bbl of seawater containing tracers with a depth of investigation of ∼4 to 5 meters. All three SWCTT's indicated low S orw values, ranging from 0.05 to 0.20 with a nominal average of 0.15. Similar results from all three SWCTT's indicate that microscopic displacement efficiency is very good; eliminating the option of chemical EOR. The current field development plan is focused on improving volumetric sweep efficiency. Properly designed and executed SWCTT's can be considered as large-scale "laboratory waterflood tests" at true reservoir conditions (e.g., live oil, wettability and stress history). Compared to conventional SCAL tests using small plug samples, SWCTT's see a much larger rock volume and avoid wettability alteration issues that plague modern cores taken with OBM (oil based mud). Though logistically challenging in deepwater, SWCTT's can be more cost- and time-effective than taking a new core. Copyright 2011, Society of Petroleum Engineers. Source


Carlisle C.,Chemical Tracers Inc. | Al-Maraghi E.,Kuwait Oil Company | Al-Saad B.,Kuwait Oil Company | Pope G.,University of Texas at Austin
SPE - DOE Improved Oil Recovery Symposium Proceedings | Year: 2014

Kuwait Oil Company has recognized the implications of the recent technological advances that are very likely to transform the oil industry and make chemical enhanced oil recovery methods such as alkaline-surfactant-polymer (ASP) flooding a hallmark of enhanced oil recovery. An ambitious program to apply chemical EOR to both sandstone and carbonate oil reservoirs in Kuwait is already underway. In this paper, we present the first field results of this effort. First we discuss the approach used to design a novel surfactant formulation for a high-salinity, high-temperature, highly heterogeneous carbonate reservoir, the Sabriyah-Mauddud in Kuwait, and the evaluation of the ASP process in three one-spot ASP pilots (i.e., three two-stage single well chemical tracer tests). We summarize the results of the surfactant laboratory experiments used to select the final ASP formulation and we present detailed results and interpretation of the subsequent single-well chemical tracer test (SWCTTs) results using ASP chemicals as well as details of the field operation including quality control measurements performed in the field lab. The residual oil saturations measured before and after the injection of the ASP slug and polymer drives clearly show that the chemical solution was effective in mobilizing and displacing residual oil saturation following injection of water. The injectivity of high molecular weight polyacrylamide polymer was excellent despite the low permeability of the formation. Source


Khaledialidusti R.,Norwegian University of Science and Technology | Enayatpor S.,University of Texas at Austin | Badham S.J.,Chemical Tracers Inc. | Carlisle C.T.,Chemical Tracers Inc. | Kleppe J.,Norwegian University of Science and Technology
Journal of Petroleum Science and Engineering | Year: 2015

It is generally recognized that the determination of current oil saturation (Soc) and residual oil saturation (Sor) plays a significant role in production forecasting and the selection and management of enhanced oil recovery (EOR) methods. Failure to accurately determine either saturation state will lead to incorrect recovery estimates and poor understanding of EOR efficacy. While there exist several methods of determining Soc and Sor, each method benefits and suffers from advantages and disadvantages specific to that technique. In order to compensate for the shortcomings of any one specific method, a combination of testing procedures may be utilized. In this paper, we propose a combination of Log-Inject-Log (LIL) and single-well chemical tracer (SWCT) test methods to improve the accuracy of Sor measurement while simultaneously offering a novel approach to the determination of Soc. The proposed method is not still implemented in any field and in this case, the concept is offered, not confirmation through a field example.The LIL method has the advantage of being able to generate a vertical fluid saturation profile throughout a logged interval, but suffers from its strong dependence on porosity assumptions. Subsequently, any deviation between assumed porosity and actual porosity will result in a deviation between measured Sor and true Sor. By comparison, the SWCT test method is independent of porosity, but cannot detect vertical variations in Sor.The complimentary nature of these two test methods, as well as their operational reliance on fundamentally different principles, make them ideal candidates for a hybrid testing program to measure Sor with a high degree of quality assurance. As well, combining the LIL and SWCT test methods in a single testing program offers a novel approach to measuring Soc. The details and mathematical derivation of the theory behind the measurement of Sor and Soc via this hybrid approach are presented in this paper. © 2015 Elsevier B.V. Source

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