China Petroleum Exploration ›› 2025, Vol. 30 ›› Issue (1): 142-155.DOI: 10.3969/j.issn.1672-7703.2025.01.011

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Reservoir Characteristics and Formation Mechanisms of the fault-fracture carbonate gas reservoir in the Middle-Upper Jurassic of the right bank of Amu Darya River

Wang Hongjun1,Zhang Peijun2,Tang Yuzhe1,Wang Siqi1,Zhang Liangjie1,Guo Chunqiu1,Xing Yuzhong1,Dong Jianxiong3,Wang Qiang4   

  1. 1 Research Institute of Petroleum Exploration & Development; 2 China National Petroleum Corporation (CNPC)(Turkmenistan) Amu Darya River Gas Company; 3 Institute of Bureau of Geophysical Prospecting Inc., CNPC; 4 CNPC Chuanqing Drilling Engineering Company Limited
  • Online:2025-01-15 Published:2025-01-15

Abstract: The oil and gas resources in the Amu Darya Right Bank are abundant. Recently, a large-scale carbonate “ fault-fracture “ gas reservoir was discovered in the eastern region, demonstrating the excellent natural gas accumulation conditions of the carbonate rocks in this area. This study integrates seismic, core, thin section, and drilling log data to investigate the gas accumulation and enrichment patterns in the Upper Jurassic carbonate “ fault-fracture reservoir.” The study suggests that in the research area, under three different levels of faults—controlling faults, transformed faults, and micro-faults—and three types of depositional environments—shoal, mud mound, and intershoal environments—the interaction with associated corrosive fluids has led to the formation of fault-fracture with varying reservoir and permeability characteristics. These fault-fracture reservoirs include six types: shoal body-controlling fault, shoal body-intershoal-controlling fault, shoal body + transformed fault, shoal body + micro-fault, intershoal body + transformed fault, and intershoal body + micro-fault. These six types represent a new type of gas reservoir in the eastern part of the Amu Darya Right Bank. Based on the development geological parameters of several already producing “ fault-fracture “ gas reservoirs, these reservoirs can be further classified into three categories: Type I—large-scale fault-fissure bodies with strong fractures and strong corrosion near controlling faults (structural belts); Type II—local fault-fracture bodies with moderate fractures and moderate corrosion near transformed faults; and Type III—fracture-pore or fracture-type gas reservoirs with weak fractures and no corrosion in micro-faults. Among these, Type I reservoirs, with their significant advantages in reserve scale and stable high production, are the main target for further exploration potential in the region.

Key words: Amu Darya, Upper Jurassic, carbonate, reservoir, fracture, fault, fault-fracture, natural gas reservoir characteristics

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