关键词: 浅层页岩气, 常压区, 勘探潜力, 五峰组—龙马溪组, 背斜型, 渝东南地区

Abstract: Based on the exploration and development results and evaluation of marine shale gas in Sichuan Basin and its peripheral area, the geological conditions and exploration potential of shallow shale gas in Luolong anticline and Laochangping anticline in southeast Chongqing area are studied. By combining wells, seismic, and experimental analysis data, shale gas accumulation conditions and controlling factors of sweet spots are analyzed, and five basic geological characteristics of shale gas in shallow anticline in southeast Chongqing area are identified: (1) The shale reservoir was developed in deep-water shelf facies, showing superior geochemical indexes, with the thickness of high-quality shale of 29-37.5 m, and TOC of 2.01%-6.39%; (2) The shale reservoir has good physical properties, with organic pores developed and porosity of 3.29%-6.58%; (3) The shale formation is dominated by normal pressure, with pressure coefficient of 0.96-1.08 by micro-injection pressure drop test. The total gas content measured by in-situ desorption experiment is 0.66-5.67 m³/t, with the adsorbed gas accounting for 69.97%-78.6%; (4) Shale has high brittle mineral content (quartz content of 30.3%-75.5%), high brittleness index of 59%-65%, shallow burial depth of 880-1100 m, and low in-situ stress (average maximum horizontal principal stress of high-quality shale of 29 MPa), which is favorable for volume fracturing engineering; (5) Although it has experienced multi-stage tectonic transformation, the shale still has certain preservation conditions, and presents an anticline type gas accumulation pattern. On the whole, the fracturing parameters of shale gas in shallow anticline in southeast Chongqing area are low, which is conducive for fracturing engineering. However, engineering technology should be further optimized, and the improvement of single well production and reduction of construction cost be considered, so as to achieve the benefit development.