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- Title
四川盆地震旦系气藏TSR证据及控制因素.
- Authors
刘强; 鲁雪松; 范俊佳; 柳少波; 马行陟; 戴博凯; 桂丽黎; 陈玮岩
- Abstract
Comprehensive analysis of reservoir bitumen, fluid inclusion composition, sulfur distribution and sulfur isotope characteristics in Sinian system, Gaoshiti-Moxi area of Sichuan Basin, shows that thermochemical sulfate reduction (TSR) occurred in the Gaoshiti-Moxi area, but the TSR is weak and it is mainly controlled by hydrothermal fluid flow related to strike-slip faults. Main evidences are as follows: (1) Sulfide and sulfate minerals such as galena, sphalerite, pyrite and barite are developed in many Sinian reservoirs in outcrops of the peripheral area of Sichuan Basin and Gaoshiti-Moxi area. The sulfur isotope is characterized by high δ34S values, which are generally greater than 12‰, indicating that the source of sulfur is seawater and related to TSR. (2) The S/C range of Sinian solid bitumen in Gaoshiti-Moxi area is 0.031-0.059, which has typical characteristics of TSR bitumen. (3) The content of H2S in some fluid inclusions is high, and the fluid inclusions containing elemental sulfur, bitumen and calcite daughter crystals are direct evidence of TSR. (4) The content of H2S in Sinian gas reservoir is 0.24%-6.8%, with an average of 1.22%. It is a micro-high H2S gas reservoir. The absence of gypsum deposits in the formation and SO42- in the formation water is quite low, which is completely different from the global high sulfur gas reservoir where TSR occurs, indicating that the effect intensity of TSR in Sinian gas reservoir is weak. (5) Wells, which have found sulfide in the Sinian system in Gaoshiti-Moxi area, are mainly located near the NW and NWW strike-slip faults, and the distribution is obviously controlled by faults. TSR may be derived from deep hydrothermal fluids communicated by faults, and TSR is mainly developed near faults, which is fault-controlled TSR. H2S generated by TSR of hydrocarbons in Sinian reservoirs in Sichuan Basin promotes the formation of lead-zinc deposits and other sulfide deposits, that is, hydrocarbon accumulation, cracking and fracture fluid activity, TSR and the formation of MVT type lead-zinc deposits are closely linked, which is an ideal area for the study of deep organic-inorganic interaction.
- Subjects
SICHUAN Sheng (China); SULFATE minerals; CALCITE crystals; GAS reservoirs; FLUID inclusions; SULFUR isotopes; GYPSUM; SULFIDE minerals
- Publication
Natural Gas Geoscience, 2022, Vol 33, Issue 6, p929
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2022.02.002