Natural fractures in ultra-deep reservoirs of China: A review

Zeng, Lianbo; Song, Yichen; Liu, Guoping; Tan, Xiaolin; Xu, Xiaotong; Yao, Yingtao; Mao, Zhe

doi:10.1016/j.jsg.2023.104954

Cited by 12 publications

(2 citation statements)

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“…Previous studies have demonstrated that the formation and development of tectonic fractures in carbonate reservoirs are closely relevant to the original sedimentary, diagenetic process, and tectonic movement. 14 , 29 ,− 58 According to the characteristic disparity of tectonic fractures in the Feixianguan carbonates, this study identifies and discusses five geological factors that may primarily control the development and distribution of tectonic fractures, including lithology, rock mechanical stratigraphy, reservoir physical property, diagenetic cementation, and faults.…”

Section: Discussionmentioning

confidence: 99%

“…Influenced by multiple diagenetic and tectonic processes within a long-term geological period, deep and ultradeep carbonate reservoirs are typically characterized by complex spatial distribution, strong heterogeneity, and abundant natural fractures. − Carbonate reservoirs are generally considered as dual permeability media with fluid flow through the matrices and natural fractures. , Due to the poor physical properties of the reservoir matrix in deep and ultradeep carbonates, natural fractures can improve pore connectivity by providing well-connected seepage pathways, which dominate the hydrocarbon reserves, percolation capacity, and fluid-flow pattern in reservoirs. − In addition, natural fractures can also increase the wellbore instability, affect the extension direction of hydraulic fractures, and determine the completion methods. − Therefore, understanding the characteristics, development mechanisms, and distribution patterns of natural fractures is crucial to the deep and ultradeep carbonates during the process of reservoir characterization, drilling operations, and production management. − …”

Section: Introductionmentioning

confidence: 99%

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Characteristics and Controlling Factors of Natural Fractures in Deep Carbonates of the Puguang Area, Sichuan Basin, China

Shi,

Zhao,

Zhang

et al. 2024

ACS Omega

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Understanding the types, characteristics, and controlling factors of natural fractures in deep and ultradeep carbonates is crucial for evaluating reservoir quality, optimizing well deployment, and comprehending their impact on hydrocarbon exploitation. Multiple types of natural fractures are widespread in the deep carbonates of the Feixianguan Formation in the Puguang area, northeastern Sichuan Basin, China, and the main controlling factors are complex. Based on geological, geophysical, and experimental data, this study defined fracture types and analyzed the fracture development characteristics in the deep Feixianguan carbonates. On this basis, the main geological factors that control the development and distribution of tectonic fractures were discussed by combining statistical and experimental analyses. Results indicate that natural fractures in the Feixianguan Formation can be genetically classified into tectonic and diagenetic fractures. Specifically, tectonic fractures include shear fractures and tensile fractures, in which the former are predominant. In the Feixianguan carbonates, tectonic shear fractures are mainly developed in the NE-SW and near E-W strikes, with dip angles mostly ranging from 30 to 70°. The majority of shear fractures appear on a small scale and have good effectiveness. The fracture heights and apertures are commonly less than 50 cm and 25 μm, respectively, and unfilled fractures account for more than half. The distribution and development of tectonic fractures are mainly controlled by lithology, mechanical stratigraphy, reservoir physical properties, diagenetic cementation, and faults. In the Feixianguan carbonates, tectonic fractures are more developed in crystalline dolomite. With the increasing thickness of mechanical stratigraphy, the fracture density decreases and the scale increases. The presence of early dissolution pores can prevent the formation of later tectonic fractures. Tectonic fractures in the NNW-SSE and near N-S strikes generally possess poor effectiveness due to multiple cementations after their formation. In the vicinity of faults, tectonic fractures generally stretch subparallel to the extension direction of the fault, and the development degree of fractures close to major faults is higher.

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Section: Discussionmentioning

confidence: 99%