天然气工业2024，Vol.44Issue(2)：52-67,16.DOI:10.3787/j.issn.1000-0976.2024.02.006
四川盆地南部向斜区二叠系岩溶孔隙型石灰岩储层成因与天然气勘探新领域
Permian karst porous limestone reservoir in the syncline area of southern Sichuan Basin:Origin and new field of natural gas exploration
摘要
Abstract
With the continuous advancement of oil and gas exploration,the exploration direction gradually expands from structural highs to syncline areas.According to the traditional understanding,the reservoirs in syncline areas are generally tight,so how to find high-quality reservoirs is one of the key factors to achieve breakthroughs in oil and gas exploration in syncline areas.Taking the limestone of Middle Permian Maokou Formation in the syncline area of southern Sichuan Basin as an example,this paper comprehensively analyzes the drilling cores,thin sections,well logging and geochemical data.Based on this,the characteristics and genesis of porous limestone reservoirs in syncline areas are researched.In addition,a reservoir development model is established,and the new direction of natural gas exploration is pointed out.And the following research results are obtained.First,the karst porous carbonate reservoir developed in the Maokou Formation in the syncline area of southern Sichuan Basin is lithologically dominated by micritic-sparry bioclastic limestone and sparry bioclastic limestone,and its reservoir space is mainly acted by the pores formed through fabric selective dissolution,such as biological coelomopores,biological moldic pores and intragranular dissolved pores.Second,the average porosity of the Maokou Formation reservoir in the study area is 4.07%,and the average permeability is 0.273 mD.There is a significant positive correlation between porosity and permeability,so it is a typical porous reservoir.Third,the Maokou Formation reservoir is in a low content of Al,Sc,Zr and total rare earth(ΣREE)as well as the content of Mn and Fe.Its carbon isotope values are within the distribution range of those of calcite precipitated in the Middle Permian seawater,and the oxygen isotope shows a certain negative bias.Fourth,the formation of the karst porous reservoir in the Maokou Formation is related to the penecontemporaneous karst,which is controlled by the sedimentary microgeomorphology and the high-frequency sequence,and the dissolution fluid is mainly meteoric water.In conclusion,karst porous reservoirs are generally developed in the Sichuan Basin,and this kind of reservoir is far away from unconformity and modified by penecontemporaneous karstification controlled by sedimentary palaeogeomorphology and facies belt.Therefore,the exploration target should be changed to"favorable sedimentary facies belts controlling reservoirs in a large scale",and syncline area will be an important new field for future natural gas exploration in the Sichuan Basin.关键词
孔隙型储层/岩溶储层/准同生期岩溶/中二叠统茅口组/四川盆地南部/向斜区Key words
Porous reservoir/Karst reservoir/Penecontemporaneous karst/Middle Permian Maokou Formation/Southern Sichuan Basin/Syncline area引用本文复制引用
肖笛,黄天海,张本健,刘冉,高兆龙,李明隆,杨文杰,谭秀成..四川盆地南部向斜区二叠系岩溶孔隙型石灰岩储层成因与天然气勘探新领域[J].天然气工业,2024,44(2):52-67,16.基金项目
国家自然科学基金项目"四川盆地早中二叠世白云岩及储层差异成因与峨眉山大火成岩省幕式响应"(编号:42172166)、中国石油天然气股份有限公司上游领域基础性前瞻性项目"残留型海相盆地构造—岩相古地理重建技术研究"(编号:2021DJ0501). （编号:42172166）
