琼东南盆地深水区基岩潜山超压成因及油气成藏特征  

Origin of the Overpressure and Hydrocarbon Accumulation Characteristics of Bedrock Buried Hills in the Deepwater Area,Qiongdongnan Basin

作　　者：胡林 胡潜伟 王思雨 江汝锋 汪紫菱 赵晨 田澜希 张超梦 卞恺歌 Hu Lin;Hu Qianwei;Wang Siyu;Jiang Rufeng;Wang Ziling;Zhao Chen;Tian Lanxi;Zhang Chaomeng;Bian Kaige(Hainan Branch,CNOOC,Haikou 570311,China;Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中海石油(中国)有限公司海南分公司,海南海口570311 [2]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074

出　　处：《地球科学》2025年第2期433-452,共20页Earth Science

基　　金：“十四五”重大科技项目《南海深水盆地油气运聚成藏分析与突破方向》(No.KJGG-2022-0103);湖北省自然科学基金创新群体项目(No.2021CFA031).

摘　　要：海洋深水区是当今全球油气勘探的热点,随着深水油气勘探的不断推进,基岩潜山逐渐成为重要的接替领域.近年来,琼东南盆地深水区基岩潜山气藏获得了重大突破,展现了潜山重要的勘探潜力.但是基岩潜山普遍存在高压,超压如何影响规模成藏是亟需解决的一个重要问题.基于此,以陵水32-1基岩潜山为例,通过已钻井岩心、薄片观察、温压场模拟、流体包裹体等综合分析,揭示潜山内部存在两个压力系统,上部压力系数为1.68,下部压力系数为1.76~1.85.10.48 Ma时凹陷内烃类流体压力传导至潜山,潜山开始发育超压;3.02 Ma时潜山压力系数达1.7,进入强超压阶段.LS32-1-A井分别在3.0~1.9 Ma和1.8 Ma~现今经历两期油气充注,充注时间与潜山超压形成时间一致.研究表明:(1)潜山储层可分为砂砾质带、风化带、致密带、内幕裂缝带,以潜山内幕裂缝、基底断裂及垂向微裂隙为天然气运移的主要通道;(2)超压成因主要为早期欠压实和生烃增压,晚期受烃类流体侧向压力传导控制;(3)强超压形成时间与烃类流体充注时间匹配性好,生烃凹陷内的压力演化以及流体向潜山的充注过程控制着潜山大型油气藏形成;(4)陵水32-1构造具有“近源供烃,优势充注;超压传导,内幕成储;超压封盖,规模保存”的成藏模式.研究为琼东南盆地深水区基岩潜山油气藏的进一步勘探提供了重要依据.Deepwater reservoirs are the hotspot of global oil and gas exploration.With the continuous development of deepwater exploration,overpressure bedrock buried hills have gradually become an important successor field.The breakthrough of Lingshui 32-1 buried hill gas reservoir in the western deepwater area of the Qiongdongnan Basin reveals the insider fracture reservoir as well as the formation of large gas fields,and demonstrates the exploration potential of Lingnan Low Uplift buried-hills.However,overpressures are prevalent in buried hills,and how overpressure affects gas reservoir accumulation is a vital issue that needs to be solved urgently.To explore the overpressure characteristics,development mechanism of overpressure,and the relationship between overpressure and hydrocarbon accumulation,the drilled cores,thin-section observation,numerical simulation,and fluid inclusions analyses were utilized,revealed the two pressure systems,with an upper pressure coefficient of 1.68 and a lower pressure coefficient of 1.76 to 1.85,and two phases of gas filling from 3.0 to 1.9 Ma and from 1.8 Ma to the present day,respectively,and the gas filling process is consistent with the overpressure formation.Lingshui 32-1 buried hill consists of gravelly reservoirs,weathered crust reservoirs,tight interval,and internal fracture reservoirs.The fracture,basement fault,and vertical microfracture are the main channels for natural gas migration.The overpressure mechanism of Lingshui 32-1 buried hill is mainly due to disequilibrium compaction and hydrocarbon pressurization in the early stage,and lately controlled by lateral transmission of fluids pressure.The timing of strong overpressure formation matches well with the gas filling.The overpressure within the depression and the gas filling process into the buried hills control the gas reservoir accumulation.Eventually,an accumulation model of overpressure-controlled hydrocarbon generation,transmission,filling,and preservation developed.This study provides an important basis for further exp

关 键 词：超压 基岩潜山 流体充注 深水区 琼东南盆地 石油地质 

分 类 号：P744.4[天文地球—海洋科学]