滇东曲靖地区筇竹寺组页岩气成藏地质特征分析

发布时间：2018-07-08 21:31

  本文选题：筇竹寺组 + 页岩气　； 参考：《中国矿业大学》2015年硕士论文

【摘要】：下寒武统筇竹寺组是我国页岩气勘探开发的有利层系之一,其形成时间早、热演化程度高,经历了复杂的地质演化历程。从成藏角度认识筇竹寺组页岩气地质特征,很有必要。论文以滇东曲靖地区下寒武统筇竹寺组为研究对象,通过资料收集整理、野外地质调查、岩芯观测、实验测试分析等手段,从地质背景、沉积环境、源岩-储层特征、成藏地质过程、赋存特征与保存条件五个方面对曲靖地区筇竹寺组页岩气成藏地质特征进行了分析。研究区位于上扬子板块南缘滇黔隆褶带,在区域地质背景研究基础上,结合野外地质调查成果,系统梳理了本区沉积-构造演化特征,将其划分为四个阶段:原古特提斯洋阶段、古特提斯洋阶段、燕山运动阶段、喜马拉雅运动阶段。利用层序地层学理论,将区内下寒武统划分为6个三级层序,形成一个有序的海水进退旋回,其中筇竹寺组位于Sq2与Sq3层序。将筇竹寺组划分为浅水陆棚、半深水陆棚和深水陆棚三个沉积亚相及六个沉积微相,其沉积环境经历了四个主要的演化过程。筇竹寺组富有机质泥页岩主要发育于Sq2层序海侵体系域,富有机质泥页岩厚度70~120m,埋深0~4500m。筇竹寺组富有机质泥页岩有机质类型以I型为主,有机质成熟度(Ro)4.2%,有机质丰度(TOC)平均2.88%。筇竹寺组页岩储层以炭质页岩、粉砂质页岩为主,石英含量较高,孔隙主要有机质孔、粒内孔、粒间孔等类型。根据压汞曲线形态,区内页岩储层可分为两种类型,以第二类储层为主,其压汞曲线滞后环较窄,连通性较差,孔径分布不连续,孔隙度偏低,平均为2.53%。与龙马溪组相比,本区筇竹寺组页岩热演化程度更高,储层孔隙度偏低、孔隙连通性偏差。上述特征可能指示了过高的热演化程度不利于页岩储层孔隙的发育。运用“构造-埋藏-受热-生烃”的研究思路,探讨了本区页岩气成藏的地质过程。地层厚度趋势分析法、沉积速率法研究表明,QD1井印支期以来累计剥蚀量超过5800m。筇竹寺最大埋深出现在中三叠世晚期,埋深达7000m,最大受热温度可达270℃左右,主要生烃时期为C-P时期。总结了本区筇竹寺组页岩气藏的三个主要特点:沉积环境有利于形成良好的物质基础,储层成岩改造作用强烈,成藏过程生烃期早、隆升强烈。等温吸附实验揭示筇竹寺组最大吸附量平均2.95cm3/g,气测录井揭示筇竹寺组全烃含量平均0.011%,现场解析实验表明其平均含气量约0.54m3/t。从构造条件、地下水条件、盖层特征、气体组分四个方面分析了本区筇竹寺组页岩气保存条件。总体而言,本区筇竹寺组页岩气藏浅部保存条件较差,推测深部有较好保存条件。
[Abstract]:The Qiongzhusi formation of the Lower Cambrian is one of the favorable strata for shale gas exploration and development in China. It is necessary to understand the geological characteristics of shale gas in Qiongzhusi formation from the perspective of reservoir formation. This paper takes Qiongzhusi formation of Lower Cambrian in Qujing area of eastern Yunnan as the research object. By means of data collection, field geological investigation, core observation, experimental test and analysis, the paper analyzes the geological background, sedimentary environment, source rock-reservoir characteristics, and so on. The geological characteristics of shale gas accumulation of Qiongzhusi formation in Qujing area were analyzed from five aspects: the geological process of reservoir formation, the characteristics of occurrence and the conditions of preservation. The study area is located in the Yunnan-Qianlong fold belt of the southern margin of the upper Yangtze plate. On the basis of the study of the regional geological background and combined with the results of the field geological survey, the sedimentary and tectonic evolution characteristics of the area are systematically combed. It can be divided into four stages: the PaleoTethys stage, the Yanshanian stage and the Himalayan stage. Based on sequence stratigraphy, the Lower Cambrian in this area is divided into six third-order sequences to form an orderly seawater advance and retreat cycle, in which Qiongzhusi formation is located in the Sq2 and Sq3 sequences. Qiongzhusi formation is divided into three sedimentary subfacies: shallow water shelf, semi-deep water shelf and deep water shelf, and six sedimentary microfacies. The sedimentary environment of Qiongzhusi formation has undergone four main evolution processes. The organic-rich shale of Qiongzhusi formation is mainly developed in the Sq2 sequence transgressive system tract, with a thickness of 70 ~ 120m and a depth of 0 ~ 4500m. In Qiongzhusi formation, the organic matter types of organic matter rich shale are mainly type I, organic matter maturity (Ro) 4.2 and organic matter abundance (TOC) 2.88 on average. The shale reservoirs of Qiongzhusi formation are mainly carbonaceous shale, silty shale, high quartz content, main organic pore, intragranular pore, intergranular pore and so on. According to the shape of mercury injection curve, shale reservoir in this area can be divided into two types, mainly the second type reservoir. The hysteresis loop of mercury injection curve is narrower, the connectivity is poor, the pore size distribution is discontinuous, the porosity is low, the average is 2.53. Compared with Longmaxi formation, Qiongzhusi formation in this area has higher thermal evolution degree, lower porosity and deviation of pore connectivity. These characteristics may indicate that too high thermal evolution is not conducive to the development of shale reservoir pores. The geological process of shale gas accumulation in this area is discussed by using the research idea of "tectonic-buried, thermal-hydrocarbon-generating". The analysis of formation thickness trend and sedimentation rate method show that the cumulative denudation amount of QD1 well is more than 5800m since the Indosinian period. The maximum buried depth of Qiongzhusi appeared in the late Middle Triassic, with a buried depth of 7 000 m and a maximum heating temperature of about 270 鈩，

本文编号：2108796