China Petroleum Exploration ›› 2024, Vol. 29 ›› Issue (4): 128-145.DOI: 10.3969/j.issn.1672-7703.2024.04.010

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Research on logging evaluation methods for geological quality and gas content of deep coal measure gas

Shi Yujiang,He Yufei,Wan Jinbin,Guo Xiaokai,Yu Hongguo,Yang Renjie   

  1. China National Logging Corporation
  • Online:2024-07-15 Published:2024-07-15

Abstract: The deep coal measure gas is one of the key exploration and production targets in the field of unconventional oil and gas exploration,which has gradually grown to be a major source of natural gas resources in China. Compared with medium-shallow coalbed methane (CBM)reservoirs, the deep coal measure gas reservoirs are characterized by more complex gas occurrence and geological characteristics. For example,in B block in Ordos Basin, the deep coal measure gas shows higher gas content, better coal structure, poorer reservoir physical properties, and higher reservoir temperature, pressure, and formation water salinity than that in middle-shallow formations. The geological characteristics of deep CBM have systematically been analyzed, which support to summarize the typical logging response characteristics of coal seams, such as low density, low GR, high neutron, high acoustic time difference, and high resistivity, and achieve the identification of coal reservoir; After analyzing the different logging response characteristics of various coal structures, some logging parameters have optimally been selected to establish coal structure factors applicable for the target area and classify coal structure types; Based on experimental results and combined with logging response characteristics of target interval, a porosity logging interpretation model has been established by using variable matrix parameters of coal rocks; Based on the experimental data, the correlation between logging response and macerals has been analyzed, as well
as that between macerals, which supports to construct a proximate component logging evaluation model in the target area; After conducting geological quality parameters evaluation such as coal seam identification, maceral calculation, and coal structure classification, the conventional and NMR-isothermal adsorption combined gas content evaluation technology has been developed to calculate both free gas and adsorbed gas in deep coal reservoirs, providing guarantees for the calculation of deep coal measure gas resources and reserves; Furthermore, with the aim of further improving the exploration efficiency and development benefits of deep coal measure gas, logging suggestions and technical research directions for the evaluation of deep coal reservoir have been proposed, so as to meet the goal of high-quality development of the deep coal measure gas industry.

Key words: deep coal measure gas, logging evaluation, gas content, logging series, research direction

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