鄂尔多斯盆地奥陶系盐下马四段天然气成藏新认识及勘探重大突破  

New understandings on gas accumulation and major exploration breakthroughs in subsalt Ma 4 Member of Ordovician Majiagou Formation,Ordos Basin,NW China

作　　者：何海清 郭绪杰 赵振宇[2] 席胜利[3] 王居峰[2] 宋微[2] 任军峰[3] 吴兴宁[2] 毕赫 HE Haiqing;GUO Xujie;ZHAO Zhenyu;XI Shengli;WANG Jufeng;SONG Wei;REN Junfeng;WU Xingning;BI He(PetroChina Exploration&Production Company,Beijing 100007,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;PetroChina Changqing Oilfield Company,Xi'an 710018,China)

机构地区：[1]中国石油勘探与生产分公司,北京100007 [2]中国石油勘探开发研究院,北京100083 [3]中国石油长庆油田公司,西安710018

出　　处：《石油勘探与开发》2022年第3期429-439,共11页Petroleum Exploration and Development

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目“中国石油风险勘探重点领域研究评价及年度部署”。

摘　　要：基于大量钻井、测井和地震资料分析,对鄂尔多斯盆地奥陶系盐下马家沟组四段天然气地质条件与成藏主控因素开展研究,提出古隆起控相、控储、控藏新认识:①马家沟组沉积期,中央古隆起分隔盆地中东部华北海与西南缘秦祁海两大沉积体系,在马四段台缘带发育巨厚丘状颗粒滩相白云岩,同时控制盆地中东部形成“两隆两凹”古地理格局,其中水下低隆带发育台内滩相白云岩,隆间低洼区发育泥灰岩。②由中央古隆起至盆地东缘,马四段白云岩逐渐减薄并相变为灰岩,灰岩致密带侧向封挡形成大面积白云岩岩性圈闭。③加里东末期中央古隆起遭受不同程度剥蚀,面积达6×10^(4) km^(2),上古生界石炭系—二叠系煤系优质烃源岩大面积披覆沉积,成为下伏奥陶系盐下白云岩岩性圈闭规模供烃主体。④印支期—燕山期盆地西倾掀斜,中央古隆起下拗转变为高效供烃窗,上古生界煤系烃源岩通过中央古隆起高孔渗白云岩体向上倾高部位侧向供烃,盐下海相烃源岩作为重要的气源补充,通过加里东期断裂、微裂缝输导供烃。以新认识为指导,转变勘探思路,综合评价优选盆地中东部马四段两大有利勘探区,部署实施两口风险探井均钻遇较厚马四段(含)气层,其中1口井获高产工业气流。该研究推动了奥陶系盐下马四段天然气勘探的历史性突破,开辟了鄂尔多斯盆地天然气勘探的重要新领域。Geological conditions and main controlling factors of gas accumulation in subsalt Ma 4 Member of Ordovician Majiagou Formation are examined based on large amounts of drilling, logging and seismic data. The new understandings on the control of paleo-uplift over facies, reservoirs and accumulations are reached:(1) During the sedimentary period of Majiagou Formation, the central paleo-uplift divided the North China Sea in central-eastern of the basin from the Qinqi Sea at southwest margin of the basin, and controlled the deposition of the thick hummocky grain beach facies dolomite on platform margin of Ma 4Member. Under the influence of the evolution of the central paleo-uplift, the frame of two uplifts alternate with two sags was formed in the central-eastern part of the basin, dolomite of inner-platform beach facies developed in the underwater low-uplift zones, and marl developed in the low-lying areas between uplifts.(2) From the central paleo-uplift to the east margin of the basin,the dolomite in the Ma 4 Member gradually becomes thinner and turns into limestone. The lateral sealing of the limestone sedimentary facies transition zone gives rise to a large dolomite lithological trap.(3) During the late Caledonian, the basin was uplifted as a whole, and the central paleo-uplift was exposed and denuded to various degrees;high-quality Upper Paleozoic Carboniferous-Permian coal measures source rocks deposited on the paleo-uplift in an area of 60 000 km;, providing large-scale hydrocarbon for the dolomite lithological traps in the underlying Ma 4 Member.(4) During the Indosinian-Yanshanian stage, the basin tilted westwards, and central paleo-uplift depressed into an efficient hydrocarbon supply window. The gas from the Upper Paleozoic source rock migrated through the high porosity and permeability dolomite in the central paleo-uplift to and accumulated in the updip high part;meanwhile, the subsalt marine source rock supplied gas through the Caledonian faults and micro-fractures as a significant supplementary. Under th

关 键 词：鄂尔多斯盆地 奥陶系 盐下 马家沟组四段 中央古隆起 岩性相变带 天然气成藏 米探1井 

分 类 号：TE122.1[石油与天然气工程—油气勘探]