川西坳陷东坡古构造恢复及其对天然气成藏的控制作用

发布时间：2018-03-09 01:24

本文选题：剥蚀厚度　切入点：古构造恢复　出处：《长江大学》2017年硕士论文　论文类型：学位论文

【摘要】：川西坳陷中段东坡属于川西坳陷东部的一个次级构造单元,包含合兴场-高庙子、丰谷、永太、中江-回龙和知新场-石泉场共计5个三维地震勘探区块,是四川盆地内部重要的含油气构造单元。正确认识川西坳陷东坡古构造形态及其对油气藏形成的控制作用,对于指导川西坳陷东坡沙溪庙组油气勘探具有重要意义。论文根据烃源岩的生烃演化史,结合流体包裹体分析确定研究区气藏的成藏期次和时间。通过对钻井、测井等资料的分析处理,利用声波时差法恢复东坡地区喜山期剥蚀厚度,应用2DMove软件编制构造发育史剖面,并采用等厚图法恢复沙溪庙组JS11、JS14、JS23、JS24-1、JS31-2、JS33-1、JS33-2和JS33-3等8个砂组成藏期古构造面,分析沙溪庙组构造演化及对天然气运移、聚集和调整的控制作用。自印支晚幕以来地层持续埋深,地层沉降控制烃源岩的生排烃时间,须五段烃源岩于145Ma达到生烃门限开始生烃,105Ma左右进入生烃高峰期,受喜山运动影响在72Ma生烃停滞。流体包裹体系统分析成果揭示,研究区有三期成藏:第一期成藏时间为141~128Ma左右,油气可能已经被破坏;第二期成藏时间为105~88Ma;第三期成藏时间为83~68Ma。成藏关键时刻在烃源岩的生烃高峰期105~72Ma。川西坳陷经历了安县运动、印支晚幕运动、多期的燕山运动和喜山运动。成藏期燕山运动产生近东西向的挤压构造应力,形成南北向构造带的雏形,沉降响应上孝泉-丰谷地区表现为快速沉降,知新场-石泉场地区形成一些断层遮挡构造,在地层中发育一些“Y”字型断层,形成断背构造圈闭。燕山早期发育的F1-1、F2、F3、F4、F8等主要烃源断层对天然气从下部须家河组运移到上部沙溪庙组起到良好通道作用。喜山运动在东坡地区的剥蚀厚度普遍在1000m以上,沿南北向构造呈现南高北低特征。知新场靠近断裂带地区,地层剥蚀厚度接近1500m,中江-回龙地区剥蚀厚度相对较小,高庙地区剥蚀量大于丰谷地区,研究区从西向东剥蚀厚度表现减小的特征。研究区成藏动力主要为地层压力,地层压力的演化过程决定了成藏动力的演化过程。东坡地区在燕山期经历了三期幕式排烃过程,地层压力演化表现为早期高压、中晚期逐渐脱气泄压至常压。喜山期,由于地层抬升剥蚀和构造挤压应力传导产生异常高压,传递性高压控制喜山期成藏动力,气体在地层压力下向构造高点聚集。成藏期东坡地区的构造高部位主要有合兴场背斜、丰谷背斜和中江-回龙背斜,这些在成藏期就已经形成的规模较大的古构造脊控制了天然气优势运移路径的局部分布,油气由构造低部位向高部位逐渐收敛,在构造高点聚集形成以构造为主的构造-岩性气藏。喜山期研究区构造反转,南部地区剧烈隆起,沿南北向构造呈现南高北低特征,地层抬升和构造形态的改变调整了原有气藏的分布。
[Abstract]:The east slope of the middle section of the western Sichuan depression belongs to a sub-structural unit in the eastern part of the western Sichuan depression, which contains five 3D seismic exploration blocks, including Hexing Chang-Gaomiaozi, Fenggu, Yongtai, Zhongjiang-Huilong and Zhixinchang-#china_person0# fields. It is an important oil and gas bearing structural unit in Sichuan basin. The paleotectonics on the east slope of western Sichuan depression and its controlling effect on the formation of oil and gas reservoirs are correctly understood. It is of great significance to guide oil and gas exploration in Shaximiao formation, Dongpo, West Sichuan depression. According to the hydrocarbon generation evolution history of source rock, combined with fluid inclusion analysis, this paper determines the time and time of gas reservoir formation in the study area. Based on the analysis and processing of logging data, the erosion thickness of Himalayan period in Dongpo area was restored by sonic time difference method, the structural development history profile was compiled by 2DMove software, and the 8 sandstone paleotectonic surfaces composed of JS33-1JS33-2 and JS33-3 in Shaximiao formation were restored by isoparkographic method, including JS11J1414, JS2323, JS24-1, JS31-2, JS33-1J33-2, and JS33-3, etc. The tectonic evolution of Shaximiao formation and its control on migration, accumulation and adjustment of natural gas are analyzed. The source rocks of the Xuwu formation reached the hydrocarbon generation threshold of 145 Ma and began to enter the peak period of hydrocarbon generation at about 105 Ma, and the hydrocarbon generation stagnated at 72 Ma due to the Himalayan movement. The results of fluid inclusion system analysis revealed that the source rocks reached the peak of hydrocarbon generation at 145 Ma and began to enter the peak of hydrocarbon generation at 105 Ma. There are three stages of reservoir formation in the study area: the first stage is about 141 ~ 128 Ma, and the oil and gas may have been destroyed; The second stage of reservoir forming time is 105 ~ 88 Ma, the third period is 836 ~ 68 Ma. The key time of reservoir formation is 105 ~ 72 Ma. the West Sichuan depression has experienced Anxian movement and Indosinian late curtain movement. During the accumulation period, the Yanshanian movement produced nearly east-west compressive tectonic stress, forming the embryonic form of the south-north tectonic belt, and the subsidence response to the rapid subsidence in Shangxiaoquan-Fenggu area was observed in response to the multi-stage Yanshanian movement and the Himalayan movement. Some fault-blocking structures were formed in the Zhixinchang-#china_person0# Chang area, and some "Y" shaped faults were developed in the strata. The main hydrocarbon source faults, such as F1-1F2F2F3F4F8, played a good role in the migration of natural gas from the lower Xujiahe formation to the upper Shaximiao formation. The denudation thickness of the Himalayan movement in the Dongpo area was generally more than 1000m. Along the north and south direction, the denudation thickness of the strata is close to 1500 m, the denudation thickness of the Zhongjiang-Huilong area is relatively small, and the denudation amount of the Gaomiao area is larger than that of the Fenggu area. The characteristics of denudation thickness decrease from west to east in the study area. The reservoir forming power in the study area is mainly the formation pressure, the evolution process of the formation pressure determines the evolution process of the reservoir forming dynamics. The Dongpo area experienced three stages of curtain expulsion process during the Yanshanian period. The evolution of formation pressure shows early high pressure, gradual degassing and releasing pressure to normal pressure in the middle and late stage. During the Himalayan period, the reservoir forming power was controlled by transitive high pressure because of the abnormal high pressure caused by strata uplift and denudation and tectonic compression stress conduction. The gas accumulates to the high point of the structure under the formation pressure. In the East Slope area during the reservoir forming period, the structural high positions are mainly Hexing Chang anticline, Fenggu anticline and Zhongjiang Huilong anticline. These paleotectonic ridges, which have been formed in the reservoir forming period, control the local distribution of the dominant migration path of natural gas, and the oil and gas gradually converge from the low part of the structure to the high part. The tectonic-lithologic gas reservoirs are formed in the high points of the structures. The tectonic inversion in the Himalayan study area, the sharp uplift of the southern regions, and the characteristics of the south high and the north low along the north and south trending are the main features of the tectonic-lithologic gas reservoirs. The distribution of the original gas reservoirs is adjusted by stratigraphic uplift and structural changes.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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