构造热演化与页岩气的改造和保存研究

尹宏伟 邱楠生 刘绍文 王勤 刘大永

摘 要：该文重点开展了中国南方典型盆地构造热演化特征及页岩气形成的地质背景的研究，初步开展了构造改造对页岩储层物性和页岩气赋存形式的影响的研究。所取得的主要进展有：（1）以全面调研及大量野外地质调查为基础，结合地球物理资料解释与分析，多尺度详细剖析下扬子地区的构造特征，盆地演化及其对关键暗色页岩分布与保存的影响，揭示江阴-无锡滑脱褶皱带为相对稳定区块；（2）以野外地质调查、样品采集及室内扫描电镜观测为基础，结合挤压构造活动数值模拟，探索了构造改造对下扬子页岩储集空间的影响，揭示了强烈的挤压、剪切会严重破坏页岩中的孔洞结构，但断层活动影响的范围有限，褶皱冲断带内的宽缓向斜页岩气保存条件较好；（3）Ro以及新获得的低温热年代学测试数据研究结果表明四川盆地热历史可大致以260 Ma为界分为P2末期之前的热流升高阶段和之后的热流降低阶段及随后的低热流发展阶段，晚二叠世峨眉山地幔柱和中晚三叠世以来前陆盆地演化是四川盆地热演化主要影响因素。

关键词：下扬子地区 四川盆地 构造演化 构造变形样式 页岩气保存

Abstract：For the first two years， our research focused on the Tectono-thermal evolution and shale gas formation geological background of typical basins in southern China. And we have started to investigate the influences of structural alternation on the shale reservoir and shale gas occurrence. 10 faculties and 12 graduate students worked in this project. More than 2000 papers of geological background have been collected. 653 samples from 128 observation sites were collected during the past 7 field works. And we have mapped 10 geological cross sections and accomplished more than 700 experimental tests. The major progresses so far include： 1）Based on the analysis of field observation，drilling data and geophysical data，we interpreted the structural deformation characteristics and basin evolution of Lower Yangtze region and its influence on the distribution and preservation potential of the key shale layers. We suggest that the detachment-fold belt of Jiangyin-Wuxi is relative structural stable belt in the Lower Yangtze region； 2）Based on the field observation， sample collection and SEM analysis， and DEM modeling of compressional structural deformation， we investigated the influence of structural alternation on the reservoir properties of the Lower Yangtze shale， and concluded that strong compression and shear deformation do great damage to the pore structure of the shale， but the damage resulted from faulting is limited to the zone close to the fault， the broad synclines within the fold-and-thrust belts still have good shale gas preservation potential； 3）Based on Ro and low temperature thermochronology data， we divided the thermal history of Sichuan basin into two stages， the heat flux increasing and decreasing stages before and after later permian respectively. Emeishan mantle plume in the later permian and the tectono-thermal evolution of foreland basin since mid-later triassic are the controlling factors for the thermal evolution of the Sichuan basin.

Key Words：Lower Yangtze region；Sichuan basin；Tectonic revolution；Structural deformation styles；Shale gas preservation

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