Shiyou shiyan dizhi (Nov 2023)
Typical difference analysis and benefit-oriented development countermeasures of normal and high pressure shale gas in southeastern Chongqing
Abstract
Southeastern Chongqing is located in the transition zone of the southeastern margin of Sichuan Basin. Shale gas reservoirs of normal and high pressure are developed in this area. In order to promote normal pressure shale gas development benefits, starting from the typical difference analysis of normal and high pressure shale gas, through the research of drilling, core observation, experimental analysis, accumulation conditions, and production dynamics, combined with shale gas exploration and development practices in southeastern Chongqing, it is clarified that the normal pressure shale gas has the typical geological characteristics of small thickness of high-quality shale, low porosity, poor preservation conditions, and medium gas content. The accumulation of normal pressure shale gas is controlled by sedimentary facies, preservation conditions, and in-situ stress field. Affected by multi-stage structural transformation and differential uplift, the mechanism of normal pressure shale gas generation is complex, which has the characteristics of low initial production, short stable production period, slow decline, and high flowback rate. There are obvious differences between normal and high pressure shale gas in geological characteristics, enrichment regularities, generation mechanism, and production law. Considering the poor grade of normal pressure shale gas resources in southeastern Chongqing, four key countermeasures for the benefit-based development of normal pressure shale gas are put forward: (1) The basic geological research is furthered and the enrichment regularities and sweet spots are clarified. (2) The development technology of variable well spacing, long horizontal section, small inclined angle, strong transformation, low height difference and controlled pressure difference is established to increase the production of single well. (3) The innovation of engineering technology such as low-cost drilling and efficient fracturing is increased to achieve speed acceleration, efficiency improvement, and cost reduction. (4) The institutional mechanism is innovated and an efficient organization and operation mode is created. The four key countermeasures effectively promote the transformation of normal pressure shale gas from resources to reserves and from reserves to benefits, facilitating the efficient development of normal pressure shale gas in southeastern Chongqing.
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