Discussion on genesis and geological significance of "low resistivity and low gas content" of Longmaxi Formation shale in southeastern Sichuan

• Published in: Shi you shi yan di zhi Vol. 45; no. 6; pp. 1089 - 1096
• Main Authors: Fubin WEI, Zhujiang LIU, Feiran CHEN, Wei YAN, Qiang WANG
• Format: Journal Article
• Language: Chinese
• Published: Editorial Office of Petroleum Geology and Experiment 01-11-2023
• Subjects: graohitization; high water content; longmaxi formation; low resistivity; preservation condition; shale gas; southeastern
• ISSN: 1001-6112
• DOI: 10.11781/sysydz2023061089

In order to clarify the genesis of "low resistivity and low gas content" in the shale of Wufeng-Longmaxi formations and effectively guide the next step of shale gas exploration in Sichuan Basin, a detailed study on the problem based on a large number of drilling surveys, dissections, and analysis of laboratory test results in the entire area was carried out herein. Low-resistivity wells of Longmaxi Formation shale in this area can be divided into two types based on their electrical and geological characteristics, which are less than 1 Ω·m and 1-10 Ω·m. Shale gas wells with resistivity less than 1 Ω·m are basically gas-free and mostly dry wells with relatively concentrated distribution areas, mainly located in southwestern Sichuan and western Changning. The resistivity curve of the shale exhibits a "thin neck" characteristic, with a Raman reflectance generally above 3.70% and a high amplitude graphite peak. In addition, the variation range of resistance values in rock electrical experiments under different sta