高陡复杂构造带深层页岩气保存条件差异性分析——以川东南綦江高陡复杂构造带为例

Differences in preservation conditions of deep shale gas in high-steep complex tectonic belt: taking Qijiang high-steep complex tectonic belt in southeast Sichuan as an example

张旭亮 刘珠江 陈超 苏克露 张煜颖 陈斐然 张迪

ZHANG Xuliang LIU Zhujiang CHEN Chao SU Kelu ZHANG Yuying CHEN Feiran ZHANG Di

中国石化 勘探分公司, 成都 610041

SINOPEC Exploration Company, Chengdu, Sichuan 610041, China

川东南地区是中国页岩气勘探的重点目标之一，现阶段的勘探领域正逐步迈入深层、超深层，但由于受钻井与地震等多种因素的制约，对该地区的构造特征及页岩气保存条件的研究还不够深入。为了查明川东南地区綦江高陡复杂构造带构造变形特征及其对深层页岩气富集规律的影响，为后续勘探部署提供依据，选取典型三维地震剖面，从构造变形特征剖析入手，结合实钻数据分析，建立高陡构造模型，在此基础上开展保存条件差异的主控因素定量评价。结果表明，綦江高陡构造具备“上陡下缓+膏岩主控+前锋变陡”的分层变形特征；綦江地区发育一套大范围的寒武系膏盐层，其塑性形变对上覆构造的隆起起到控制作用；区内影响页岩气保存条件的因素包含主动变形强度、断裂体系、断面正应力、构造与地应力夹角、顶板滑脱层等，各因素相互作用，导致研究区内部保存条件差异明显。据此，建立了綦江高陡构造保存条件评价标准，明确隆盛—桃子荡构造带构造应力单一，主动变形强度低，构造封闭性强，是下一步勘探的主要有利目标。

The southeastern Sichuan Basin is one of the key targets for shale gas exploration in China. Currently, the exploration has gradually been delved into deep and ultra-deep formation fields. However, due to various constraint factors such as drilling and earthquakes, research on the tectonic characteristics and shale gas preservation conditions in this area is inadequate. In order to find out the tectonic deformation characteristics of Qijiang high-steep complex tectonic belt in southeast Sichuan and its impact on the enrichment law of deep shale gas, and to provide a basis for subsequent exploration deployment, a high-steep structural model is established based on the analysis of tectonic deformation characteristics and practice drilling data, and the quantitative evaluation of the main controlling factors of differences in preservation conditions is carried out on the basis of the model. The research results show that: (1) Qijiang high-steep structure has the layered deformation feature of “steep upper part and flat lower part + dominated by gypsolyte + steep front”; (2)There is a widely developed Cambrian gypsum salt layer in the Qijiang area, whose plastic deformation controls the uplift of the overlying structure; (3) The factors affecting the preservation conditions of shale gas in the study area include active deformation strength, fracture system, normal stress of fault plane, angle between structure and geostress, roof detachment layer and other factors. The interaction of multiple factors leads to obvious differences in the preservation conditions in the study area. According to the analysis results, the evaluation criteria for the preservation conditions of Qijiang high-steep structures are established, and it is defined that the Longsheng-Taozidang tectonic belt has single tectonic stress, low active deformation intensity and well-closed structure, which is the main favorable target for the next exploration.

国家自然科学基金企业创新发展联合基金(U19B6003-03-03)与中国石化科技部项目(P23070)联合资助。

https://doi.org/10.11781/sysydz2023061121