鄂西渝东地区中-新生代构造变形及其对油气保存的制约

Meso-Cenozoic structural deformations and their impacts on hydrocarbon preservation in the western Hubei-eastern Chongqing area

易积正 包汉勇 李以严 张道洪 秦军 谢洪光

Jizheng YI Hanyong BAO Yiyan LI Daohong ZHANG Jun QIN Hongguang XIE

油气成藏跟构造息息相关，研究构造及油气保存条件在油气勘探中具有重要作用。研究了鄂西渝东地区断裂发育特征及构造样式的差异分布，划分了构造单元，描述了断裂、构造类型及演化，分析了构造对保存条件的影响。研究表明：鄂西渝东中扬子地块南部构造带西部中生代以来经历了多期盆-山耦合构造作用，构造变形强度大，发育基底卷入型和盖层滑脱型断层。提出了该复杂构造区油气保存条件评价的方法。评价认为齐岳山断层以西保存条件好于东侧，以万县复向斜的保存条件最好，其次为石柱复向斜。湘鄂西褶皱带以利川构造带保存条件最好，其次为恩施构造带，南北镇-桑植石门构造带最差。该研究成果在红星地区、宜恩地区页岩气、致密气、岩溶体油气勘探中的应用取得了较好的效果。

Since hydrocarbon accumulation is closely associated with structures， examining structures and hydrocarbon preservation conditions is significant for hydrocarbon exploration. In this study， we explore the fault characteristics and the differential distribution of structural styles in the western Hubei - eastern Chongqing area and classify the structural units in this area. Furthermore， we describe the types and evolution of faults and other geological structures in this area and analyze their impacts on hydrocarbon preservation. The results reveal that the western portion of the southern structural zone of the middle Yangtze Block in this area has undergone multi-stage basin-orogen couplings since the Mesozoic. This has led to a high intensity of structural deformations and the formation of basement-involved faults and cap rock-detachment faults. A method to assess the hydrocarbon preservation conditions in this structurally complex area is proposed in this study. The assessment results suggest that areas west of the Qiyueshan fault are more favorable compared with those east of it in hydrocarbon preservation. Among others， the Wanxian synclinorium displays the optimal preservation conditions， followed by the Shizhu synclinorium. In the western Hunan-Hubei fold belt， the Lichuan structural belt demonstrates the most favorable conditions for hydrocarbon preservation， succeeded by the Enshi structural belt， with the Nanbei Town-Sangzhi Shimen structural belt exhibiting the least favorable conditions. The findings of this study have proven effective in exploring shale gas， tight gas， and karst reservoirs in the Hongxing and Yi’en areas.

10.11743/ogg20240308