Progress, challenge, and prospect for exploration and development of continental shale gas in Yanchang exploration area in Ordos Basin

DU Yan1,2,3 LIU Chao1,2,3 GAO Chao1,2,3 GUO Chao1,2,3 LIU Gang1,2,3 XU Jie1,2,3 XUE Pei1,2,3

(1.Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd)
(2.Shaanxi Key Laboratory of Continental Shale Gas Accumulation and Exploitation)
(3.National Engineering Research Center of Continental Shale Gas of Petroleum and Chemical Industry)

【Abstract】As a large superimposed basin with rich oil and gas, the Ordos basin develops multiple sets of Permian and Triassic continental shale strata and is abundant in continental shale gas resources. Compared with the marine shale, the continental shale is more complicated. There are many challenges during the exploration and development of continental shale, which restrict its economic exploitation. In this paper, in terms of the geological characteristics, resources background, and technologies of exploration and development, the achievements in the practice of the exploration and development of continental shale gas in the Ordos basin were summarized. In addition, the current technical difficulties of continental shale gas were analyzed to effectively utilize opportunities and timely approach challenges in the development process. According to comprehensive analyses, the shale gas parameters in the Yanchang exploration area, such as the continental shale thickness, total organic carbon content, maturity, and gas content, have reached above the lower limit of favorable intervals of shale gas stipulated by national standards. Therefore, it meets the geological conditions for accumulation of shale gas. Under the control factors of macro and micro heterogeneous, the continental shale gas has different enrichment characteristics in terms of phase state and scale. There are two types of accumulation modes, which are adsorption accumulation and adsorption + free composite accumulation. The understanding of different accumulation mechanisms guides the selection of the favorable zone and the production from continental shale gas wells. A number of key supporting technologies have been formed during the exploration practice of continental shale gas. Logging evaluation methods suitable for strong heterogeneous continental shale have been established. The water-based drilling fluid system and a series of supporting equipment for drilling and completion have been developed. The CO2 fracturing technology system and the recovery-utilization technology of wellsite waste fluid have been formed. Meanwhile, there are still many challenges in terms of precise prediction of “sweet spot”, improvement of drilling rate and efficiency, environmental protection and efficiency improvement of fracturing, and cost reduction. At present, the exploration and development of continental shale gas in China is still in an early stage, with high costs and low initial production. It is still necessary to carry out pilot tests for the exploration and development of continental shale gas to achieve scientific and technological breakthroughs. Besides, it can form a resource replacement and promote the continental shale gas industry to obtain economic benefits.

【Keywords】 Ordos Basin; Yanchang exploration area; continental shale gas; progress in exploration and development; challenge; prospect;

【DOI】

【Funds】 National Science and Technology Major Project (2017ZX05039-001-005) National Science and Technology Major Project (2017ZX05039-002-005)

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This Article

ISSN:1672-7703

CN: 11-5215/TE

Vol 25, No. 02, Pages 33-42

March 2020

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Article Outline

Abstract

  • 0 Introduction
  • 1 Basic characteristic of continental shale gas and effectiveness of exploration and development
  • 2 Key supporting technology
  • 3 Challenge and prospect
  • 4 Conclusion
  • References