宜昌黄陵隆起构造演化及其对中下扬子页岩气勘探的启示

Structural evolution of the Huangling uplift,South China:Implications for the shale gas exploration in the middle and lower Yangtze River area

2013年以来,在四川盆地周缘黄陵隆起南部斜坡带的下寒武统、震旦系取得页岩气勘查的重大发现和突破,开拓了盆外复杂构造区页岩气勘查新方向。依据已有研究成果、区域地质资料、物探资料和钻井资料等,提出黄陵隆起从元古界以来经历了前震旦纪结晶基底形成、震旦纪初的岩体侵入、震旦纪—中侏罗世沉降沉积与隆升剥蚀交替发展、晚侏罗世—古近纪快速隆升削顶4个构造演化阶段。黄陵隆起独特的构造演化史对页岩气成藏起到了重要作用,其中震旦纪—中侏罗世沉降沉积与隆升剥蚀交替发展使早期烃源岩埋深适当,热演化程度和孔隙度适中;而强硬基底则保护了沉积盖层的相对完整性和连续性。考虑构造演化史、基底特征、盖层发育以及烃源岩等因素,对中、下扬子地区类似古隆起进行系统梳理分析,发现四川盆地外围的雪峰隆起、黔中隆起与南华北盆地的霍邱隆起石油地质条件较好,通过进一步的地质地球物理和钻探工作,有望取得油气调查的发现和突破。

Significant discoveries and breakthroughs have been made in the shale gas exploration in the southern slope zone of the Huangling uplift,periphery of the Sichuan basin.Based on previous research results,regional geological data,geophysical data and drilling data,it is proposed that the uplift has experienced four structural evolution stages since the Proterozoic,including the formation of crystalline basement in the pre-Sinian period,the intrusion of rock mass in the early Sinian period,the alternation of subsidence,deposition,uplift and denudation in the Sinian-middle Jurassic period,and the rapid uplift in the late Jurassic-Paleogene period.This distinctive structural evolution history of the Huangling uplift plays an important role in the shale gas accumulation,in which the third stage assures the appropriate depth and moderate thermal evolution and porosity,and the strong basement formed in the first stage protects the relative integrity and continuity of the sedimentary cap.We also found some uplifts with similar structural evolution history,basement and cap features as the Huangling uplift in the middle and lower Yangtze River area,such as the Xuefeng uplift and Qianzhong uplift on the periphery of the Sichuan Basin,and the Huoqiu uplift in the southern North China Basin.Through further geological,geophysical and drilling work,oil/gas reservoir may be discovered in the above uplifts.