鄂尔多斯盆地平凉北地区三叠系长7段烃源岩地球化学特征及形成环境  

Geochemical characteristics and formation environment of source rocks of Triassic Chang 7 member in northern Pingliang area,Ordos Basin

作　　者：薛楠 邵晓州[1,2] 朱光有[3] 张文选 齐亚林[1,2] 张晓磊[1,2] 欧阳思琪[5] 王淑敏 XUE Nan;SHAO Xiaozhou;ZHU Guangyou;ZHANGWenxuan;QI Yalin;ZHANG Xiaolei;OUYANG Siqi;WANG Shumin(National Engineering Laboratory for Exploration and Development of Low-Permeability Oil&Gas Fields,Xi’an 710018,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China;Department of Exploration,PetroChina Changqing Oilfield Company,Xi’an 710018,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]低渗透油气田勘探开发国家工程实验室,西安710018 [2]中国石油长庆油田公司勘探开发研究院,西安710018 [3]中国石油勘探开发研究院,北京100083 [4]中国石油长庆油田公司勘探事业部,西安710018 [5]中国石油大学(北京)地球科学学院,北京102249

出　　处：《岩性油气藏》2023年第3期51-65,共15页Lithologic Reservoirs

基　　金：国家科技重大专项“鄂尔多斯盆地大型低渗透岩性地层油气藏开发示范工程”(编号:2016ZX05050);国家科技重大专项“大型油气田及煤层气开发”(编号:2017ZX05001002)联合资助。

摘　　要：通过对鄂尔多斯盆地西南缘平凉北地区三叠系长7段15口井的暗色泥岩样品进行地球化学分析,结合测井解释成果,推断出其古沉积环境,总结了烃源岩质量的主控因素及发育模式。研究结果表明:(1)平凉北地区三叠系长7段烃源岩有机质丰度自下而上逐渐减小,长7_(3)亚段有机质丰度最大,长7_(2)亚段次之,长7_(1)亚段最小。长7_(3)亚段烃源岩有机碳质量分数最高可达12.4%,生烃潜力大,有机质类型以Ⅰ型和Ⅱ_(1)型为主,是一套处于成熟阶段的好—优质湖相烃源岩。(2)平凉北地区长7_(3)亚段沉积期气候潮湿温暖,为陆相淡水环境。较高的古生产力、缺氧还原水体为有机质的生长、繁殖和保存创造了有利条件。(3)平凉北地区长7_(3)亚段发育火山-热液型烃源岩。火山活动与热水沉积共同影响着长7_(3)亚段的水体环境,其较高的古生产力是有机质大量生成的基础,缺氧还原环境是有机质完整保存的关键因素。Through geochemical analysis of dark mudstone samples of Triassic Chang 7 member from 15 wells in northern Pingliang area,southwest margin of Ordos Basin,combined with logging interpretation results,the paleosedimentary environment was inferred,and the main controlling factors and development model of hydrocarbon source rocks were summarized.The results show that:(1)The organic matter abundance of Triassic Chang 7 source rocks in northern Pingliang area gradually decreased from bottom to top,with the highest organic matter abundance in Chang 7_(3) sub-member,followed by Chang 7_(2) sub-member,and the lowest in Chang 7_(1) submember.The organic carbon mass fraction of the hydrocarbon source rock of Chang 7_(3) sub-member is up to 12.4%,with great hydrocarbon generation potential.The organic matters are mainly type Ⅰ and type Ⅱ_(1).It is a set of good to high-quality lacustrine source rocks in mature stage.(2)The climate was moist and warm during the sedimentary period of Chang 7_(3) sub-member in northern Pingliang area,and it was a terrestrial freshwater environment.High paleo-productivity and anoxic reduction water created favorable conditions for the growth,reproduction and preservation of organic matters.(3)Volcanic-hydrothermal source rocks are developed in Chang 7_(3) submember in northern Pingliang area.Volcanic activity and hydrothermal deposition jointly affect the water environment of Chang 7_(3) sub-member.The high paleo-productivity is the basis for the formation of large amounts of organic matters,and the anoxic reduction environment is the key factor for the complete preservation of organic matters.

关 键 词：地球化学 古生产力 潮湿温暖气候 缺氧还原环境 火山-热液型烃源岩 长7段 三叠系 平凉北地区 鄂尔多斯盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]