Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (1): 124-135.doi: 10.11743/ogg20210111

• Petroleum Geology • Previous Articles     Next Articles

Geological characteristics and controlling factors of hydrocarbon accumulation in terrestrial shale in the Da'anzhai Member of the Jurassic Ziliujing Formation, Sichuan Basin

Shasha Sun1,2(), Dazhong Dong1,2, Yucong Li3, Hongyan Wang1,2, Zhensheng Shi1,2, Shiwei Huang4, Yan Chang1,2, Wenhua Bai1,2   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
    2. National Energy Shale Gas R & D(Experiment) Center, Langfang, Hebei 065007
    3. Southwest Oil & Gas Field Company, PetroChina, Chengdu, Sichuan 610400, China
    4. Daqing Oil Field Company, PetroChina, Daqing, Heilongjiang 163714, China
  • Received:2020-05-14 Online:2021-02-28 Published:2021-02-07

Abstract:

Hydrocarbon exploration in the terrestrial Jurassic system of Sichuan Basin has been focused on conventional tectonically fractured reservoirs and unconventional coquina and tight sandstone reservoirs.However, shale reservoirs are regarded as the new focal point for making significant breakthroughs in the system of the basin.Based on an analysis of the distribution, generation, reservoir properties and preservation conditions of the terrestrial shale oil/gas in the Da'anzhai Member of Ziliujing Formation, we conclude that the member is favorable for a large-scale shale oil and gas accumulation in terms of its geological features and that three factors serve to control the accumulation.Geologically, the 20-80 m thick dark shale with oil and gas shows in the 2nd sub Da'anzhai Member is both excellent source rock and over-pressured oil/gas reservoir sandwiched between cap and bottom tight limestones with its wide and continuous distribution, large thickness, well-developed pores and fractures, good physical properties, and medium-high maturity.The three factors including the semi-deep and deep lacustrine sub-facies, high-porosity reservoirs between the top and bottom limestones and medium-high maturity, jointly control the generation, preservation, enrichment of oil and gas in the shale.

Key words: geological condition, accumulation controlling factor, terrestrial shale oil & gas, Da'anzhai Member, Ziliujing Formation, Lower Jurassic, Sichuan Basin

CLC Number: