China Petroleum Exploration ›› 2024, Vol. 29 ›› Issue (1): 130-141.DOI: 10.3969/j.issn.1672-7703.2024.01.010

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Hydrocarbon accumulation mechanism and exploration breakthrough of deep tight gas in the Cretaceous Shahezi Formation in Xujiaweizi Fault Depression, Songliao Basin

Jiang Hongfu, Ai Xin, Luo Guangdong, Geng Changxi, Wang Yanzhi, Li Zhaobing, Li Wenlong, Yu Wenxue, Chen Jianguo, Gong Xiukun, Yang Weihua, Guo Jing, Chen Haibin   

  1. CNPC Daqing Drilling Engineering Corporation
  • Online:2024-01-15 Published:2024-01-15

Abstract: The glutenite in Shahezi Formation in Xujiaweizi Fault Depression in Songliao Basin has a large burial depth and tight lithology. At present, due to the insufficient understanding of controlling factors for hydrocarbon accumulation, and limited by investment cost and exploration and development technology, no breakthrough has been achieved in reserves and production in Shahezi Formation. By using seismic, core, wireline logging, mud logging and experimental data, the controlling factors for tight gas accumulation in Shahezi formation are analyzed from aspects of hydrocarbon generation potential of coal measure source rocks, distribution of tight glutenites, reservoir physical properties and formation overpressure, so as to identify gas sweet spots and guide well location deployment. The study results show that the reservoir and source rock in Shahezi formation are superimposed, and the non-buoyancy dynamic process during the accumulation of tight gas leads to the occurrence of abnormal high pressure and the pattern of gas-bearing in the entire basin. The tight glutenite reservoirs in Shahezi Formation are superimposed vertically and laterally, and multi-layer high porosity zones in the reservoir serve as the “sweet spot” of tight glutenite gas reservoir. Guided by the tight gas accumulation theory, the distribution of high-quality gas “sweet spot” has been accurately characterized and the optimal well trajectory has been designed. By giving full play to the advantage of geology and engineering integration, and aiming at the optimal and fast drilling operation and maximum reservoir reconstruction volume, a well Songshen 9-Ping 5 has been deployed, and the gas rate of 106×104 m3/d has been tested, marking a major breakthrough in tight gas reservoir in Shahezi Formation, which brings broad prospects for the future exploration and development of tight gas reservoir in Shahezi Formation in Songliao Basin.

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