川南长宁地区构造变形特征及对页岩气保存条件的影响  

Structural Deformation and Shale Gas Preservation Conditions in the Changning Area of the Southern Sichuan Basin

作　　者：杨少航 罗良[1,2] 马诗杰 薛萌 曾联波[1,2] 聂舟[3] 犹钰玲 周杨帆 YANG Shaohang;LUO Liang;MA Shijie;XUE Meng;ZENG Lianbo;NIE Zhou;YOU Yuling;ZHOU Yangfan(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;PetroChina Southwest Oil&Gas Field Company,Chengdu,Sichuan 610000,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [3]中国石油西南油气田分公司,四川成都610000

出　　处：《现代地质》2024年第6期1458-1472,共15页Geoscience

摘　　要：长宁地区位于四川盆地南部,区内上奥陶统五峰组—下志留统龙马溪组页岩品质较高,具有良好的生储盖条件。显生宙经历了多期伸展、挤压与走滑变形及强烈抬升剥蚀作用,致使页岩气保存条件十分复杂。本文从该区构造特征、构造演化出发,明确各项构造因素对页岩气保存条件的影响机制,并提出构造因素影响页岩气保存条件的综合定量评价方法,预测有利勘探区域。研究结果表明:长宁地区主要发育NE向和NW向两组构造,均为基底卷入断层上盘发育的相关褶皱,对应的主要形成期分别为燕山早期和燕山晚期,且部分NE向构造于喜山期受到走滑改造。构造改造时间、抬升剥蚀、地层倾角、多尺度断层-裂缝和现今地应力方向是影响长宁地区五峰组—龙马溪组页岩气保存条件的主要构造因素。基于各项构造要素对页岩气保存的影响,提出适用于长宁地区的页岩保存条件定量评价方法。评价结果显示,建武向斜页岩气保存条件最好,天宫堂背斜次之,双龙向斜与罗场向斜较差。The Changning area is located in the southern Sichuan Basin.The shale in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation is of high quality and exhibits favorable source-reservoir-cap conditions.During the Phanerozoic,multi-stage extension,extrusion and strike-slip deformation,along with strong uplift and denudation,resulted in very complex preservation conditions for shale gas.Based on the structural characteristics and tectonic evolution in this area,this paper examines how various structural factors influence the preservation conditions of shale gas.This study also proposes a comprehensive quantitative evaluation method for assessing shale gas preservation conditions and predicts potential exploration areas.The study results show that the Changning area mainly features two groups of structures:NE-trending and NW-trending.Both sets of structures are related to folds developed on the hanging wall of basement-involved fault.They formed during the Early and Late Yanshanian periods,respectively,and some NE-trending structures were modified by strike-slip events during the Himalayan period.The main structural factors affecting shale gas preservation conditions include the timing of tectonic transformation,uplift and denudation,stratigraphic dip,multi-scale fault-fracture systems,and the current in-situ stress direction.Based on the impact of various structural elements on the shale gas preservation,a quantitative evaluation method for assessing preservation conditions in the Changning area is proposed.The evaluation results indicate that the shale gas preservation conditions in the Jianwu syncline are the most promising,followed by the Tiangongtang anticline,Shuanglong syncline,and Luochang syncline.

关 键 词：长宁 构造变形 构造演化 五峰组—龙马溪组 页岩气保存条件 

分 类 号：P618.1[天文地球—矿床学] TE122.1[天文地球—地质学]