Abstract
The efficiency of different CO2 injection methods on oil recovery in tight oil reservoirs exhibits substantial variation. This investigation focuses on the Chang 6 Member of the Yanchang Formation, situated in the Ordos Basin, as the research subject. Two injection techniques, namely continuous CO2 flooding and CO2 huff-n-puff after flooding, were employed to scrutinize the microscopic production traits of oil. Five tight sandstones with comparable physical characteristics were selected for the study. A physical simulation flooding system was utilized to perform continuous CO2 flooding and CO2 huff-n-puff after flooding experiments at five pressures ranging from 4 MPa to 20 MPa. The NMR technology was employed to analyze the T2 spectrum of the cores before and after the experiment to quantify the micro production traits of oil at different pore scales. The experimental findings revealed that the oil recovery of the total pore increased progressively with flooding pressure during the flooding process. The highest recovery rate of 75.29% was observed during 20 MPa CO2 flooding. While the utilization degree of oil with large pores remained the highest, the contribution of oil decreased gradually. During the CO2 huff-n-puff after flooding under immiscible conditions, the increase in CO2 huff-n-puff recovery in macropores was the highest, up to 10.35%. The highest increase in oil utilization of small pores was 15.26% after miscibility, suggesting that oil in large pores was the primary contributor during the immiscible phases. After miscibility, oil in the small pores became the primary contributor. This investigation analyzes the influence of CO2 flooding and CO2 huff-n-puff after flooding injection methods on the micro pore oil production traits of tight sandstone reservoirs. The findings provide novel theoretical support for future field tests of CO2 flooding and CO2 huff-n-puff after flooding.
Copyright 2023, IFEDC Organizing Committee.
This paper was prepared for presentation at the 2023 International Field Exploration and Development Conference in Wuhan, China, 20–22 September 2023.
This paper was selected for presentation by the IFEDC Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the IFEDC Technical Team and are subject to correction by the author(s). The material does not necessarily reflect any position of the IFEDC Technical Committee its members. Papers presented at the Conference are subject to publication review by Professional Team of IFEDC Technical Committee. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of IFEDC Organizing Committee is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of IFEDC. Contact email: paper@ifedc.org.
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Acknowledgments
The project is supported by the National Natural Science Foundation of China (Grant No. 52174030 and 52204044), the Postgraduate Innovation and Practice Ability Development Fund of Xi’an Shiyou University(no. YCS21212091), Key Research and Development Program of Shaanxi Province (Grant No. 2022GY-137 and 2022JQ-528), Key Scientific Research Project of Education Department of Shaanxi Province (Grant No. 21JP095), Petro-China Innovation Foundation (No. 2020D-5007-0205), and the Youth Innovation Team of Shaanxi Universities.
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Xue, Jj. et al. (2024). Research on Microscopic Production Characteristics of Oil in Tight Sandstone Reservoirs by Different CO2 Injection Methods. In: Lin, J. (eds) Proceedings of the International Field Exploration and Development Conference 2023. IFEDC 2023. Springer Series in Geomechanics and Geoengineering. Springer, Singapore. https://doi.org/10.1007/978-981-97-0264-0_110
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