Special Oil & Gas Reservoirs ›› 2024, Vol. 31 ›› Issue (2): 47-56.DOI: 10.3969/j.issn.1006-6535.2024.02.006

• Geologic Exploration • Previous Articles     Next Articles

Reservoir Characteristics of the second Member of Sinian Dengying Formation in Penglai Gas Area of Sichuan Basin and Their Controlling Factors

Xu Shaoli1, Ma Kui1, Yang Qiang1, Xie Changqiong2, Zhang Xin1, Yan Wei1, Wu Luya1, Wang Wenzhi1   

  1. 1. PetroChina Southwest Oil & Gasfield Company, Chengdu, Sichuan 610041, China;
    2. China Nuclear Industry No. 24 Construction Co., Ltd., Mianyang, Sichuan 621000, China
  • Received:2023-04-18 Revised:2023-12-16 Online:2024-04-25 Published:2024-07-26

Abstract: Significant breakthroughs have been made in the exploration of natural gas in the second Member of the Sinian Dengying Formation in Penglai gas area, with single well production reaching new highs repeatedly, demonstrating the excellent scale reserve resources of Dengying Formation in Penglai gas area. However, the sedimentary and reservoir characteristics and their main controlling factors in the area are not yet clarified, and there are great difficulties in predicting high-quality reservoirs, which seriously hinder the next exploration deployment and reserve upgrading. In this context, in order to further deepen the study of sedimentary reservoir characteristics in Penglai gas area and reveal the main controlling factors of high quality reservoirs, a new round of sedimentary reservoirs research is carried out on the second Member of Penglai gas area using the latest rock-resistivity, seismic and testing data. The results show that the reservoir lithologies of the second Member of Dengying Formation are thrombolites and doloarenites of mound-shoal facies. The reservoir spaces include pores, karst caves and fractures. The distribution of the reservoirs varies significantly in the vertical direction, and the continuity is strong in the plane. Sedimentary facies belts, karst, and diagenesis jointly control the high-quality reservoirs. Among them, sedimentary facies belts are the basis for the formation of high-quality reservoirs in the second Member of Dengying Formation; karst determines the reservoir property. Late diagenesis is an essential factor affecting the formation of high-quality reservoirs in the second Member of Dengying Formation. The overall gas content of the second Member of Dengying Formation is good, with the development of multiple large lithological traps. Research suggests that the lithological trap bodies of mound-shoal facies under karst reformation are favorable target areas for further exploration and also new positions for increasing natural gas reserves and production in the basin by trillions of cubic meters. This study provides a foundation and research examples for clarifying the sedimentary and reservoir characteristics of the second Member of Penglai gas field and its main controlling factors to provide a reference for subsequent exploration and development work.

Key words: reservoir characteristic, karst, main controlling factor, dolomite, Penglai gas area, Sichuan Basin

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