气候变化领域集成服务门户(CCPortal): Pore structure and fractal characteristics of Ordovician Majiagou carbonate reservoirs in Ordos Basin; China

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DOI	10.1306/02251917173
	Pore structure and fractal characteristics of Ordovician Majiagou carbonate reservoirs in Ordos Basin; China
	Lai J.; Lai J.; Wang S.; Wang G.; Shi Y.; Zhao T.; Pang X.; Pang X.; Fan X.; Fan X.; Qin Z.; Fan X.
发表日期	2019
ISSN	0149-1423
起始页码	2573
结束页码	2596
卷号	103 期号:11
英文摘要	Fractal analysis was performed on carbonate core plug samples from the Ordovician Majiagou carbonate reservoirs in the Ordos Basin using mercury intrusion capillary pressure (MICP), nuclear magnetic resonance (NMR), and the X-ray computed tomography (CT) measurements to improve our understanding of the pore structure characteristics. The relationships between pore structure parameters and the fractal dimensions were investigated. The pore systems are dominated by secondary intercrystalline pores and enlarged dissolutionpores as well asmicrofractures. The fractal curves from MICP analysis break into two segments at the Swanson's parameter. The small pore-throat systems can be described by the fractal theory, whereas pores connected by relatively large throats (greater than the pore-throat radius at the Pittman's hyperbola's apex) are not cylindrical in shape, cannot be described by a capillary tubemodel, and tend to have apparent fractal dimensions larger than 3.0. The fact that the entirety of the capillary curve cannot be fit by a single fractal dimension implies that there are multiple pore systems present with different fractal dimensions. The CT analysis shows that the pores are dispersed in the three-dimensional spaces mainly with elliptical shapes. The NMR measurements are sensitive to pore-body size and MICP probes pore-throat dimensions, the latter being complementary to the pore-body-size distribution. None of the CT, MICP, and NMR techniques provide "right"or "wrong"answers to the pore-throat systems, but they probe different aspects of the pore systems. This study assumes the pore shapes to be spherical in general, and then the fractal dimension is calculated from the NMR transverse relaxation time (T2) spectrum. The fractal dimensions of all the samples are calculated, and the accuracy of the fractal model is verified by the high regression coefficients. Almost all the pore systems can be described by fractal theory, and the fractal dimensions are strongly correlated with the T2 values separating the immovable fluid and the free fluid. Microfractures may bias T2 toward larger values, making it hard to derive fractal dimensions from NMR measurements. The coexistence of small pores (pore radius < 10 mm) and large pores (>50 mm) results in a heterogeneous pore distribution and a high fractal dimension. Reservoir quality increases with the complexity degree of the microscopic pore structure. Conversely, samples that are dominated by small pore systems tend to have a lower fractal dimension and a less complex pore structure. © 2019 The American Association of Petroleum Geologists. All rights reserved.
语种	英语
scopus关键词	Anthropometry; Carbonation; Computerized tomography; Metamorphic rocks; Nuclear magnetic resonance; Petroleum reservoirs; Pore structure; Probes; Fractal characteristics; Microscopic pore structures; NMR transverse relaxations; Nuclear magnetic resonance(NMR); Regression coefficient; Structure characteristic; Three dimensional space; X-ray computed tomography; Fractal dimension; capillary pressure; carbonate; complexity; dissolution; fractal analysis; mercury (element); nuclear magnetic resonance; Ordovician; pore space; regression analysis; size distribution; tomography; China; Ordos Basin
来源期刊	AAPG Bulletin
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/143755
作者单位	State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing, China; College of Geosciences, China University of Petroleum (Beijing), Beijing, China; State Key Laboratory of Petroleum Resources and Prospecting, College of Geosciences, China University of Petroleum (Beijing), Changping, Beijing, China; Research Institute of Exploration and Development, Changqing Oilfield Company PetroChina, Xi'an, Shaanxi, China; Department of Petroleum Engineering, University of Wyoming, Laramie, WY, United States
推荐引用方式 GB/T 7714	Lai J.,Lai J.,Wang S.,et al. Pore structure and fractal characteristics of Ordovician Majiagou carbonate reservoirs in Ordos Basin; China[J],2019,103(11).
APA	Lai J..,Lai J..,Wang S..,Wang G..,Shi Y..,...&Fan X..(2019).Pore structure and fractal characteristics of Ordovician Majiagou carbonate reservoirs in Ordos Basin; China.AAPG Bulletin,103(11).
MLA	Lai J.,et al."Pore structure and fractal characteristics of Ordovician Majiagou carbonate reservoirs in Ordos Basin; China".AAPG Bulletin 103.11(2019).