China Petroleum Exploration ›› 2024, Vol. 29 ›› Issue (3): 57-67.DOI: 10.3969/j.issn.1672-7703.2024.03.006

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Cultivation practice and exploration breakthrough of geology and engineering integrated high-yield wells of ultra-deep shale gas in the Cambrian Qiongzhusi Formation in Deyang-Anyue aulacogen, Sichuan Basin

Zheng Majia1,Guo Xingwu2,Wu Ya1,Zhao Wentao3,Deng Qi2,Xie Weiyang2,Ou Zhipeng3   

  1. 1 Exploration Department, PetroChina Southwest Oil & Gasfifield Company; 2 Research Institute of Shale Gas, PetroChina Southwest Oil & Gasfield Company; 3 Branch of Shunan Gas Field, PetroChina Southwest Oil & Gasfifield Company
  • Online:2024-05-15 Published:2024-05-15

Abstract: The ultra-deep shale gas reservoir in the Cambrian Qiongzhusi Formation in Deyang-Anyue aulacogen in Sichuan Basin is characterized by old geologic age, large burial depth and high thermal evolution, leading to great difficulty in shale gas exploration and development. However, there is no direct experience to learn from both at home and abroad. In view of this, the idea of geology and engineering integration is applied to preliminarily establish the key technological system of “well deployment-drilling-fracturing-production” for cultivating high-yield wells of Qiongzhusi Formation shale gas: (1) Integrated well deployment. The understanding of “hydrocarbon accumulation controlled by aulacogen” is deepened, the distribution mode of high-quality reservoir is determined, and the technical limits for operating high-yield wells are clarified, supporting the optimization of well deployment. (2) Integrated drilling, logging, and geosteering. Based on the comprehensive evaluation of geological and engineering parameters, the optimum drilling target is selected, the well trajectory is optimized, and the geology and drilling integrated fine management is strengthened, which effectively guarantee the drilling rate of high-quality reservoir. (3) Integrated fracturing and reservoir stimulation. The integrated fracturing model is used to optimize fracturing design, forming fracturing technology of “promoting fracture complexity + expanding fracturing volume + highly fracture supporting + casing deformation prevention”, which effectively achieves the uniform fracture initiation, high-efficiency fracture propagation, full reservoir support and maximum reservoir stimulation volume. (4) Integrated fine management of flowback. The “four-factor” flowback and reservoir stimulation technology is developed, and the fine flowback and production analysis platform is established, which achieve the “double breakthroughs” of reservoir damage reduction and gas well stimulation. By using the above technology system, high-yield gas flow has been obtained in Well Zi 201 for the first time in China in the Cambrian shale reservoir with a depth of greater than 4500 m, and the replication of high-yield production has successfully been achieved in Well Weiye 1H, which support to initially identify a favorable area of nearly 3000 km2 with the depth of shallower than 5000 m and gas resources of nearly 2×1012 m3. The high-yield well cultivation technology and method lay a solid foundation for solving difficulties in large-scale and high-efficiency development of ultra-deep shale gas in the Cambrian Qiongzhusi Formation.

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