Geological characteristics and exploration direction of coal gas reservoir in deep layer of Xujiaweizi fault depression

doi:10.3969/j.issn.1672-7703.2024.04.006

Abstract

Abstract: In order to make clarify the favorable exploration of coal gas in deep Xujiaweizi fault depression, we systematical study the geological characteristics of coal gas reservoirs, such as genesis of coal gas, source, reservoir and cap-reservoir combination, by making full use of the data such as seismic, coal and geochemical. The result is that there are two kinds of coal named 1 and 2 coal, which is sediment in shallow lake and delta-front. They are generally reach the high-over-mature stage, with a thickness of 3～10m and average TOC of 29.65%.The coal gas is dominated by methane, and they are all coal-generated gas. The porosity and permeability of coal is 4.74% and 4.42mD. There are several different kinds of reservoir space such as tensile micro-fractures, primary plant tissue pores, pores and mineral pores are developed,which make the coal a favorable reservoir for coal gas in deep layer. There are two kinds of cape and three kinds of cap-reservoir combination in the coal gas, the top and bottom mudstone type and top mud and bottom sand type cap is the favorable gas cap-reservoir combination. The overpressure fluid seal box within the Shahezi Formation is a favorable condition for sealing coal gas at the same time. We selected the 1 coal in Songzhan Sag and 2 coal in Xuxi Sag as the favorable areas for coal gas enrichment area, based on various favorable reservoir-forming conditions, which is also the breakthrough direction of coal gas exploration in the future.

Key words: Xujiaweizi fault depression, Shahezi Formation, Coal gas, Accumulation conditions, exploration direction

CLC Number:

TE15

Sun Lidong, Yang Liang, Xu Jinshuang, Liu Jiajun, Li Xiaomei, Li Guozheng. Geological characteristics and exploration direction of coal gas reservoir in deep layer of Xujiaweizi fault depression[J]. China Petroleum Exploration, 2024, 29(4): 73-83.

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