川南地区页岩气井平台钻前工程物探集成技术

    Application of the integrated engineering geophysical exploration technology in the predrilling stage of shale gas well platforms in southern Sichuan Province

    • 摘要: 四川南部地区岩溶广泛发育,煤矿采空区密布,以往单一勘查手段无法准确探测与识别,造成页岩气规模化、工厂化钻井极易出现故障、复杂事件等问题。针对川南地区复杂地形地质条件,采用了高密度电法、浅层地震法、瞬变电磁法、音频大地电磁法、微动等多种工程物探方法进行试验及对比分析,总结出了川南页岩气井平台工程物探集成技术,并应用在页岩气井平台建设中。后期钻井结果显示,该集成技术能够有效识别地下1 000 m以浅岩溶、煤矿采空区、覆盖层等不良地质体,为页岩气井平台选址、井身结构优化、钻进风险预测、缩短钻进周期、生态环境保护等方面提供技术支撑,取得了显著的经济效益、社会效益和生态效益,为长宁—威远国家级页岩气示范区和川南页岩气勘查开发试验区的建设提供了技术保障,加快了川南页岩气的开发进程。

       

      Abstract: Southern Sichuan Province has widely developed karsts and densely distributed coal mine goafs, which cannot be accurately detected and identified using a single existent exploration method. Consequently, large-scale and industrial drilling for shale gas is prone to induce failures and complex events. In light of the complex topographic and geological conditions in southern Sichuan, this study conducted tests and comparative analysis using multiple engineering geophysical exploration methods including electrical resistivity imaging, shallow seismic method, transient electromagnetic method, audio-magnetotelluric method, and microtremor survey method. As a result, an integrated engineering geophysical exploration technology for shale gas well platforms in southern Sichuan was formed and applied to the construction of shale gas well platforms. As indicated by drilling results, the integrated technology can effectively identify unfavorable geological bodies (e.g., shallow karsts, coal mine goafs, and overburdens) at a depth of less than 1000 m and provide technical support for siting shale gas well platforms, optimizing casing programs, predicting drilling risks, shortening drilling cycles, and protecting ecological environment, with remarkable economic, social, and ecological benefits having been achieved. Moreover, this integrated technology provides a technical guarantee for the construction of both the Changning-Weiyuan national shale gas demonstration zone and the southern Sichuan shale gas exploration and development pilot zone and accelerates the shale gas development in southern Sichuan.

       

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