川中灯影组古岩溶储层成岩序列及成储—成藏效应  

Diagenetic Sequence,Reservoir-forming and Hydrocarbon Accumulation Effect of Paleokarst Reservoirs in the Dengying Formation,Central Sichuan Basin

作　　者：谷一凡 王岩松 周刚 武鲁亚 蒋裕强[1,2] 王海军 GU YiFan;WANG YanSong;ZHOU Gang;WU LuYa;JIANG YuQiang;WANG HaiJun(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Reservoir Evaluation Department,PetroChina Key Laboratory of Unconventional Oil and Gas Resources,Chengdu 610500,China;Research Institute of Petroleum Exploration and Development,PetroChina Southwest Oil and Gas Field Company,Chengdu 610041,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都610500 [2]中国石油非常规重点实验室储层评价实验室,成都610500 [3]中国石油西南油气田勘探开发研究院,成都610041

出　　处：《沉积学报》2024年第6期2088-2101,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42202166)。

摘　　要：【目的】川中地区震旦系灯影组古岩溶储层是我国海相天然气勘探的重点目标,具有成岩历史长、改造期次多、非均质性强等特点,导致油气成藏结果复杂化,制约了下步大规模勘探开发。【方法】对灯影组古岩溶储层开展了成岩矿物序列识别、激光原位U-Pb同位素定年、激光原位元素含量测试,结合岩心物性测试和图像软件识别,厘清了该区灯影组储层类型、成岩序列及成储—成藏效应。【结果】灯二段储层和灯四段储层均可被划分为缝洞型和孔洞型两种类型。识别出9个阶段的成岩—成藏事件,成岩流体可划分为3种类型:海水、被改造海水和热液流体。3期海水胶结(分别对应606±21 Ma、604±42 Ma和590±15 Ma)、3期热液活动(分别对应403±30 Ma、259.4±3 Ma和199±12 Ma)等成岩事件对储层物性具有破坏性。【结论】成岩演化过程中的古孔隙度恢复结果表明,灯二段缝洞型储层在古油藏形成阶段、原油裂解成气阶段、气藏调整阶段始终具有运聚能力,孔洞型储层则在后两个阶段具备运聚能力。灯四段的缝洞型储层和孔洞型储层在三个关键成藏阶段均具有运聚能力。[Objective]The paleokarst reservoirs of the Sinian Dengying Formation in the central Sichuan Basin are key targets for marine natural gas exploration in China,characterized by long diagenetic history,multiple diagenetic events,and strong heterogeneity.These characteristics lead to the complexity of oil and gas accumulation results,which restricts the next large-scale exploration and development.[Methods]By diagenetic mineral sequences,U-Pb isotope dating and laser in-situ element measurement in the Dengying Formation paleokarst reservoirs,combined with physical property testing of cores and image software identification,reservoir type,diagenetic sequence,reservoirforming and hydrocarbon accumulation effect are determined.[Results]Two-types reservoir are identified in the 2nd and 4th members of the Dengying Formation:a fracture-vug type and a pore-vug type.Nine-stages diagenesishydrocarbon accumulation events were identified.The diagenetic fluids were of three types:seawater,modified seawater and hydrothermal.Multi-stage diagenetic events including three-stages seawater cementation(606±21 Ma,604±42 Ma and 590±15 Ma)and three-stages hydrothermal activity(403±30 Ma,259.4±3 Ma and 199±12 Ma)had destructive effects on reservoir physical properties.[Conclusions]Reconstructed paleoporosity for the period of diagenetic evolution indicate that the fracture-vug type of reservoirs in the 2nd member of the Dengying Formation always enabled hydrocarbon migration and accumulation during the formation stage of paleo-oil reservoirs,also during the stage of crude oil cracking into gas and during the stage of gas reservoir adjustment.Pore-vug type reservoirs allowed migration and accumulation only in the latter two stages.In the 4th member,fracture-vug reservoirs enabled migration and accumulation in all three stages of hydrocarbon accumulation.

关 键 词：U-PB同位素定年 古岩溶储层 震旦系 成岩序列 灯影组 川中地区 

分 类 号：P618.13[天文地球—矿床学]