西南石油大学学报(自然科学版) ›› 2020, Vol. 42 ›› Issue (5): 1-12.DOI: 10.11885/j.issn.1674-5086.2019.04.29.03

• GEOLOGY EXPLORATION •     Next Articles

Characteristics and Main Controlling Factors of the Middle Permian Qixia Formation Reservoir in Shuangyushi Structure

PENG Xian1, PENG Jun2, ZHANG Lianjin1, LIN Pan2, LAN Xuemei1   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina Southwest Oil & Gas Field Company, Chengdu, Sichuan 610051, China;
    2. School of Geosciences and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China
  • Received:2019-04-29 Online:2020-10-10 Published:2020-10-10

Abstract: For the characteristics and main controlling factors of dolomite reservoir in Qixia Formation of Shuangyushi structure in northwestern Sichuan Basin, based on field outcrop, core and well logging data, combined thin section analysis, casting thin section, SEM, cathodoluminescence, this paper analyzes the development characteristics and main controlling factors of dolomite reservoirs in this area. The results show that the reservoirs are distributed in the NE-SW direction along the front of the Longmenshan mountain, with a thickness between 10 and 40 m. The reservoirs which develop in the shoal of platform margin facies are mainly crystalline dolomites, followed by a small amount of grain dolomites; The reservoir spaces are dominated by dissolution pores (vugs), followed by a small amount of cracks; The porosity of Qixia Formation reservoirs ranges from 1% to 4%, the permeability ranges from 0.001 mD to 10.000 mD; the reservoir types are mainly fracture-pore (vug) type. The development and distribution of reservoirs are controlled by sedimentary facies, sedimentary paleogeomorphology, diagenesis, and late tectonic fracture. Sedimentation provides the material basis for reservoir development and sedimentary highlands of paleogeomorphology control the distribution of high-energy shoal area; Penecontemporaneous atmospheric water eluviation not only forms a large number of secondary dissolution pores (vugs), but also provides migration pathway for the fluid of dolomitization; The early pores (vugs) are maximally inherited and preserved during the stage of the shallow burial dolomitization; The cracks formed by the late tectonic fracture further connect the pores (vugs) system.

Key words: reservoir characteristics, crystalline dolomites, main controlling factors, Middle Permian Qixia Formation, Shuangyushi structure

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