超压盆地水力破裂与天然气成藏的关系——以莺歌海盆地乐东斜坡区LD-A气田为例  

Relationship between hydraulic fracture and natural gas accumulation in over-pressured basin:A case study on the LD-A Gas Field in the Ledong slope belt of the Yinggehai Basin

作　　者：贾茹 付晓飞[1,2,3] 范彩伟 靳叶军[1,2,3] 王升 王海学 罗静爽 JIA Ru;FU Xiaofei;FAN Caiwei;JIN Yejun;WANG Sheng;WANG Haixue;LUO Jingshuang(Institute of Unconventional Oil&Gas,Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development,Ministry of Education,Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Sanya offshore Oil&Gas Research Institute,Northeast Petroleum University,Sanya,Hainan 572025,China;CNOOC China Limited Zhanjiang Company,Zhanjiang,Guangdong 524000,China)

机构地区：[1]东北石油大学非常规油气研究院 [2]东北石油大学“陆相页岩油气成藏及高效开发”教育部重点实验室 [3]东北石油大学三亚海洋油气研究院 [4]中海石油(中国)有限公司湛江分公司

出　　处：《天然气工业》2024年第6期23-32,共10页Natural Gas Industry

基　　金：国家自然科学基金项目“高温高压背景下重力流水道岩性圈闭油气保存条件研究”(编号:42002152);黑龙江省自然科学基金项目“高温高压背景下重力流岩性圈闭有效性研究”(编号:LH2021D006);海南省院士创新平台科研项目“莺歌海盆地构造演化特征及砂箱物理模拟技术分析”(编号:YSPTZX202301)。

摘　　要：莺歌海盆地乐东斜坡区LD-A气田的发现进一步证实了高温高压岩性圈闭领域的巨大资源潜力。该气田储层压力系数最高可达2.3,流体超压诱发的水力破裂对天然气的运聚起到重要的控制作用,明确超压条件下地层是否发生水力破裂及其演化过程是深入研究莺歌海盆地天然气成藏的关键。为此,在明确天然气垂向输导体系的基础上,以岩石破裂准则为理论依据,利用地应力及岩石抗张强度确定水力破裂模式,厘定了地层水力破裂条件;最终结合超压演化,分析了水力破裂动态演化过程对天然气成藏过程的控制作用。研究结果表明:(1)断裂、亚地震断裂和裂缝共同构成了LD-A气田天然气垂向输导体系,超压诱发的水力破裂控制了输导体系的启闭性和有效性,决定了天然气能否规模富集。(2)LD-A气田的中深层发育张性水力破裂,其中LD-A1气区现今黄流组顶部处于水力封闭状态,梅山组顶部处于水力渗漏状态;LD-A2气区和LD-A3气区上中新统黄流组顶部和中中新统梅山组顶部现今均处于水力封闭状态。(3)LD-A气田的水力破裂演化存在封闭—破裂—封闭型(LD-A1气区与LD-A2气区)和持续封闭型(LD-A3气区)2种类型,不同的水力破裂演化过程导致了天然气在不同层位砂体差异性充注和富集。结论认为,LD-A1气区与LD-A2气区浅层上新统莺歌海组二段和上中新统黄流组优质砂体是天然气有利富集对象,LD-A3气区应在埋藏更深的梅山组砂岩中寻找突破。The successful discovery of the LD-A Gas Field in the Ledong slope belt of the Yinggehai Basin confirms the huge hydrocarbon resource potential in high-temperature and high-pressure lithologic trap.The reservoir pressure coefficient in this gas field can reach 2.3,and hydraulic fracture induced by fluid over-pressure plays an important role in controlling the migration and accumulation of natural gas.Therefore,the key to the further study of natural gas accumulation in the Yinggehai Basin is to determine whether any hydraulic fracture occurs under the over-pressure conditions and what its evolution process is.In this paper,the vertical migration system of natural gas is clarified.Then,with the rock failure criterion as the theoretical basis,a hydraulic fracturing mode is determined by using the in-situ stress and the tensile strength of rocks,and the conditions of hydraulic fractures in the formation are clarified.Finally,combined with the over-pressure evolution process,the controlling effect of dynamic evolution of hydraulic fractures on the process of natural gas accumulation is analyzed.And the following research results are obtained.First,faults,sub-earthquake faults and fractures together constitute the vertical migration system of natural gas in the LD-A Gas Field.Hydraulic fractures induced by over pressure control the opening and closing of the migration system and its effectiveness,which determines whether natural gas can be enriched in a large scale.Second,in the LD-A Gas Field,tensile hydraulic fractures are developed in middle-deep layers.The top Huangliu Formation and the top Meishan Formation are currently in the state of hydraulic sealing and hydraulic leakage,respectively in the LD-A1 gas region,and both in the state of hydraulic sealing in the LD-A2 and the LD-A3 gas regions.Third,two types of hydraulic fracture evolution are identified in the LD-A Gas Field,including sealing-fracturing-sealing type(LD-A1 and LD-A2 gas regions)and continuous sealing type(LD-A3 gas region).Different evolution pro

关 键 词：莺歌海盆地 乐东斜坡区 超压 水力破裂 输导体系 天然气成藏 

分 类 号：TE122.1[石油与天然气工程—油气勘探]