天然气工业2024，Vol.44Issue(2)：30-39,10.DOI:10.3787/j.issn.1000-0976.2024.02.004
鄂尔多斯盆地奥陶系马家沟组四段优质白云岩储层发育特征及成因机制
Development characteristics and genetic mechanisms of high-quality dolomite reservoirs in the 4th Member of Ordovician Majiagou Formation in the Ordos Basin
摘要
Abstract
Well Mitan 1 in the Ordos Basin achieves a new discovery of natural gas in the dolomite section of the 4th Member of the Ordovician Majiagou Formation(hereinafter referred to as the Ma 4 Member),showing good natural gas exploration prospect,but the development characteristics and distribution laws of the dolomite reservoirs of Ma 4 Member are not understood clearly,which restricts their exploration deployment in the next step.Based on the data such as core,thin section,industrial CT,U-Pb dating,physical property analysis and geochemical characteristics,this paper systematically studies the development characteristics and genetic mechanisms of the dolomite reservoirs in the Ma 4 Member,and predicts the distribution of dolomite reservoirs and the favorable natural gas exploration zones in the Ordos Basin.And the following research results are obtained.First,in the Ma 4 Member,mound-beach facies dolomite reservoir and porphyry dolomite reservoir are mainly developed,among which,the former is lithologically composed of psammitic-psephitic dolomite,fine to medium crystalline dolomite,powder to fine crystalline dolomite and stromatolitic dolomite,and the latter is lithologically composed of porphyry powder to fine crystalline dolomite,porphyry powder crystalline dolomite and porphyry limy dolomite.Second,the reservoir space in the mound-beach facies dolomite reservoir is dominated by intercrystalline(dissolution)pores with a small number of dissolution cavities,residual intergranular pores and microfractures,with an average porosity of 5.06%.The reservoir space in the porphyry dolomite reservoir is dominated by intercrystalline pores,with a small number of intercrystalline dissolution pores and microfractures,with an average porosity of 2.46%.Third,the development of mound-beach facies dolomite reservoir is mainly controlled by microbial mounds and granular beaches,and has undergone penecontemporaneous dolomitization and burial dolomitization.The development of porphyry dolomite reservoir is mainly controlled by biological disturbance,penecontemporaneous dolomitization and burial dolomitization.Fourth,the development of mound-beach bodies,the degree of biological disturbance and the formation of dolomitized fluids are under the joint control of the tectonic paleogeographic pattern and sea level fluctuation.In conclusion,the high-quality dolomite reservoirs of Ma 4 Member are distributed in a large scale along the central paleo-uplift and the Shenmu-Zhidan low uplift.In addition,the dolomite reservoirs of Ma 4 Member in the Shenmu-zhidan low uplift are located in the lithological facies change zone,where reservoir-caprock configuration is good and natural gas is enriched with a predicted favorable exploration area of 18000 km2.关键词
鄂尔多斯盆地/奥陶系/马家沟组四段/白云岩储层/构造古地理格局/海平面升降变化Key words
Ordos Basin/Ordovician/The 4th Member of Majiagou Formation/Dolomite reservoir/Tectonic paleogeographic pattern/Sea level fluctuation引用本文复制引用
于洲,罗晓容,周进高,胡子见,魏柳斌,李靖,师平平,曹斌风,吕玉珍..鄂尔多斯盆地奥陶系马家沟组四段优质白云岩储层发育特征及成因机制[J].天然气工业,2024,44(2):30-39,10.基金项目
中国石油天然气股份有限公司科技重大项目"海相碳酸盐岩有效储层形成与保持机理及分布预测研究"(编号:2021DJ0503)、中国石油长庆油田公司重大科技专项"鄂尔多斯盆地中元古界—奥陶系构造沉积演化、成源机制与勘探新领域研究"(编号:ZDZX2021). （编号:2021DJ0503）
