摘要
过去半个多世纪以来,中二叠统茅口组一直是四川盆地天然气的主力产层之一,近年来以白云岩储层为目标,掀起了新的勘探高潮。然而,在储层成因的认识上,目前还缺乏针对各类储集空间的形成机制的系统研究,制约了下一步的滚动勘探。为此,以阐明川中龙女寺地区茅口组二段白云岩储层特征及成因为主要目标,依据地表露头、钻井、测井和地震解释等资料,从构造作用约束的角度出发,开展了储层形成机制的研究。结果表明:①茅口组白云岩储层岩性主要为细—中晶白云岩,由滩相颗粒灰岩经白云石化形成;②储集空间类型主要为热液冲击破裂孔洞和非选择性溶蚀孔洞,构造裂缝和溶缝作为次要的储集空间类型在热液运移和提高储层渗流方面起到了重要作用。③海西期峨眉地裂运动和勉略洋北向俯冲所控制的基底断裂活动诱发了中二叠世晚期川北台盆的形成,并控制了台盆边缘滩相颗粒灰岩的分布;④在较高的古地温梯度、残余的海源流体和随断裂运移的热液流体所提供的丰富的镁离子的作用下,滩相颗粒灰岩被广泛白云石化;⑤海西期的断裂—裂缝—热液活动以及印支期的断裂—裂缝活动控制了区内茅口组白云岩储层各类储集空间的形成;⑥构造作用是川中地区茅口组白云岩储层形成的主要控制机制,下一步滚动勘探应当重视断裂集中分布区域。
The Middle Permian Maokou Formation has been one of the major gas-producing horizons in the Sichuan Basin for more than half a century.A new exploration upsurge targeting the dolomite reservoirs has been set off in recent years.However,the lack of system-atical study on the genetic mechanisms of various reservoirs limits progressive exploration.To clarify the characteristics and genesis of do-lomite reservoirs in the second member of Maokou Formation in the Longnvsi area of central Sichuan Basin,the genetic mechanisms of the reservoirs were investigated with the tectonism and using the data of outcrops,drilling,logging,and seismic interpretation.The results show that,(i)the dolomite reservoirs in the Maokou Formation are primarily composed of fine-to medium-crystalline dolomites formed by the dolomitization of beach grainstones;(ii)the reservoir spaces are dominantly made of hydrothermal impact-induced vugs and non-selective karst vugs,followed by structural fractures and karst fissures which play an important role in hydrothermal migration and reservoir seepage enhancement;(iii)the Hercynian Emei taphrogeny and the basement faulting controlled by the northward subduction of the Mian-lue Ocean induced the formation of the northern Sichuan platform basin in the Late Middle Permian,and controlled the distribution of beach grain-stones at the margin of the platform basin;(iv)affected by the high paleogeothermal gradient,remnant marine-originated fluids,and abun-dant magnesium ions from hydrothermal fluids migrating along faults,the beach grainstones were dolomitized extensively;(v)the Hercynian fault-fracture-hydrothermal activity and the Indosinian fault-fracture activity controlled the space formation of the dolomite reservoirs;and(vi)tectonism is the key controlling mechanism for the formation of dolomite reservoirs.The areas where faults are concentrated should be focused on for progressive exploration.
作者
方进
张连进
郑斌嵩
李顺
刘芳兰
梁新玉
彭军
FANG Jin;ZHANG Lianjin;ZHENG Binsong;LI Shun;LIU Fanglan;LIANG Xinyu;PENG Jun(Central Sichuan Oil and Gas District,PetroChina Southwest Oil&Gasfield Company,Suining,Sichuan 629000,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China)
出处
《天然气勘探与开发》
2023年第4期13-26,共14页
Natural Gas Exploration and Development
基金
中国石油西南油气田公司川中油气矿项目“龙女寺地区茅口组气藏储层展布及有利区优选”(编号:XNS川中矿JS2022—135)。
关键词
白云岩储层
茅口组二段
龙女寺地区
储层特征
储层成因
构造作用
Dolomite reservoir
The second member of Maokou Formation
Longnvsi area
Reservoir characteristic
Reservoir gene-sis
Tectonism
作者简介
方进,男,1969年生,高级工程师,主要从事油气田开发方面的研究工作。地址:(629000)四川省遂宁市船山区河东新区香林南路178号。E-mail:fang_jin@petrochina.com.cn;通信作者:郑斌嵩,男,1990年生,博士,讲师,主要从事沉积学与石油地质学方面的研究工作。地址:(610500)四川省成都市新都区新都大道8号。E-mail:michael199062@126.com。
