鄂尔多斯盆地奥陶系盐下马四段高含硫天然气成藏特征与勘探潜力  

Accumulation characteristics and exploration potential of high-sulfur gas in the Ma 4 Member of Ordovician subsalt,Ordos Basin

作　　者：刘新社[1] 杨智[1] 魏柳斌[2,3] 张才利[2,3] 师平平 王前平[2,3] 武春英[2,3] LIU Xinshe;YANG Zhi;WEI Liubin;ZHANG Caili;SHI Pingping;WANG Qianping;WU Chunying(Exploration Division,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;National Engineering Laboratory of Low-permeability Oil&Gas Exploration and Development,Xi'an,Shaanxi 710018,China)

机构地区：[1]中国石油长庆油田公司勘探事业部 [2]中国石油长庆油田公司勘探开发研究院 [3]低渗透油气田勘探开发国家工程实验室

出　　处：《天然气工业》2024年第11期50-59,共10页Natural Gas Industry

基　　金：中国石油天然气股份有限公司科技项目“海相碳酸盐岩油气规模增储上产与勘探开发技术研究”(编号:2023ZZ16YJ01);中国石油长庆油田公司科学研究与技术开发项目“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:2021DZZ01);“鄂尔多斯盆地深层海相低丰度烃源岩生烃机理研究及潜力评价”(编号:2024D1JC02)。

摘　　要：鄂尔多斯盆地奥陶系马家沟组四段(以下简称马四段)是马家沟组沉积持续时间最长海侵期形成的碳酸盐岩层,为一套陆表海台地沉积背景下的碳酸盐岩沉积建造,也是多年来高含硫天然气勘探关注的重点层系。为了进一步明确鄂尔多斯盆地奥陶系马四段高含硫天然气成藏特征和勘探潜力,基于地震、测井、钻井等资料,重新厘定了古构造格局,系统研究了生储盖组合及匹配关系,深化了对马四段高含硫天然气成藏的认识。研究结果表明:①马四段地层沉积时期具有东高西低的古构造格局,为典型的大型陆表海碳酸盐岩缓坡沉积背景;②首次在马四段发现以微生物碳酸盐岩为主的烃源岩层,有机碳含量平均可达1%,厚度为2~6 m;③马四段白云岩储层受高频层序旋回控制,纵向上发育多套薄储层,储层平面上连片分布;④马四段发育准连续型致密碳酸盐岩气藏,具有低丰度海相烃源岩供烃,层控性白云岩储集体成储,连续分布的厚层膏盐岩封盖,垂向运移为主、近源聚集成藏,构造高部位、断裂带富集的特征,初步落实有利含气面积1.8×10^(4)km^(2)。结论认为:①提出了马四段发育海相烃源岩及供烃的新观点,证实了低丰度海相烃源岩也能形成规模油气聚集;②马四段高含硫气藏有望成为盆地海相深层油气勘探的重要战略接替新领域,并明确了盆地马家沟组致密碳酸盐岩气藏勘探方向。The fourth member of the Ordovician Majiagou Formation(Ma 4 Member)in the Ordos Basin is a set of carbonates that was formed during the transgression period when the deposition of the Majiagou Formation lasted the longest.It is a set of sedimentary formation of carbonate rocks under the depositional background of epicontinental marine platform,and has been the key strata of highsulfur gas exploration for many years.To further clarify the accumulation characteristics and exploration potential of the high-sulfur gas in the Ma 4 Member in the Ordos Basin,this paper redetermines the paleotectonic pattern based on seismic,well logging,drilling and other data.In addition,the source-reservoir-caprock assemblages and their relationships are investigated systematically,and the accumulation pattern of the Ma 4 Member high-sulfur gas is clarified.The following results are obtained.First,the paleotectonic pattern during the deposition of the Ma 4 Member was high in the east and low in the west in a typical sedimentary environment of large epicontinental carbonate gentle slope.Second,for the first time,a source rock layer primarily composed of microbial carbonate rocks was discovered in the Ma 4 Member,with an average organic carbon content of 1%and a thickness of 2-6 m.Third,the Ma 4 Member dolomite reservoirs are controlled by high-frequency sequence cycles,exhibiting multiple thin layers vertically and continuous distribution laterally.Fourth,a quasi-continuous tight carbonate gas reservoir is developed in the Ma 4 Member with marine source rocks for hydrocarbon supply,layer controlled dolomite as reservoir,and continuous thick gypsum-salt rock for sealing,and it is characterized by vertical migration,near-source accumulation,and enrichment at the structural high and fault zone.It is preliminarily confirmed that its favorable gas-bearing area is 1.8×10^(4)km^(2).In conclusion,a new idea that marine source rocks are developed in the Ma 4 Member for hydrocarbon supply is put forward,and it is confirmed that low-abundance ma

关 键 词：鄂尔多斯盆地 奥陶系盐下 马家沟组 高含硫天然气 异常高压 成藏特征 勘探潜力 

分 类 号：TE122.1[石油与天然气工程—油气勘探]