川中地区中二叠统茅口组储层特征及有效物性下限  

Characteristics and lower limits of physical properties of reservoirs in Middle Permian Maokou Formation,central Sichuan Basin

作　　者：徐诗雨 曾乙洋 林怡 祝怡 肖雪薇 赵春妮 何开来 李怡雯 XU Shiyu;ZENG Yiyang;LIN Yi;ZHU Yi;XIAO Xuewei;ZHAO Chunni;HE Kailai;LI Yiwen(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院,四川成都610041

出　　处：《天然气勘探与开发》2024年第4期38-45,共8页Natural Gas Exploration and Development

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目(编号:2022KT0401)。

摘　　要：储层有效物性下限是识别有效储层、确定储层有效厚度的关键参数,是提交天然气地质储量的一项必要研究内容。川中地区中二叠统茅口组储层有效物性下限常类比川东地区下三叠统飞仙关组、上二叠统长兴组碳酸盐岩储层,但其区域地质条件、沉积环境、成岩作用、岩石类型等均存在明显差异,严重影响了地质储量估算的精度,制约着该区茅口组气藏的勘探开发。本次研究基于钻井、测井、岩心、分析化验等资料,系统分析川中地区茅口组气藏储层特征,综合利用最小流动孔喉半径法、产能模拟法、单层试气法确定储层有效物性下限。研究结果表明:(1)川中地区茅口组储集岩类包括细晶云岩、少量砂屑云岩、灰质云岩以及云质灰岩;(2)研究区储集空间以各类溶蚀孔洞为主,裂缝和喉道是重要的渗流通道,储渗空间类型多、几何形态复杂,具较强的非均质性;(3)受溶蚀孔洞及微裂缝发育等因素影响,采用全直径样品实验结果反映研究区物性水平,总体表现为低孔低渗、局部发育高孔渗段的特征;(4) 3种方法综合确定储层有效孔隙度下限为1.97%,渗透率下限0.009 0 mD,为识别有效储层、确定有效储层厚度、估算地质储量等提供参考依据。The lower limit of physical properties is a key parameter for identifying effective reservoirs and determining their net pays,as well as a necessary subject in estimating gas in place(GIP).The lower limits of physical properties of effective reservoirs in the Middle Permian Maokou Formation,central Sichuan Basin,are often in analogy to those of carbonate reservoirs in the Lower Triassic Feixianguan and Upper Permian Changxing Formations,eastern Sichuan Basin.However,the Maokou Formation reservoirs are sig-nificantly different in regional geological conditions,sedimentary environments,diagenesis,and rock types,seriously impacting the accuracy of GIP estimation and restricting the exploration and development.The reservoir characteristics of the Maokou Formation were systematically analyzed based on drilling,logging,core,and analytic data.And then the lower limits of physical properties were determined by utilizing the methods of minimum flow pore-throat radius,productivity simulation,and single-layer gas testing.The results show that,(i)the Maokou Formation reservoirs are composed of fine-crystalline dolomites,as well as a small amount of psam-mitic dolomites,limy dolomites,and dolomitic limestones;(ii)the reservoir spaces in the study area are dominated by various disso-lution pores/vugs,with fractures and throats acting as key flow pathways;such spaces are diverse in types and complex in geometry,with strong heterogeneity;(iii)considering the development of dissolution pores/vugs and microfractures,the experimental results of full-diameter samples were used to reflect the physical properties,showing generally low porosity and permeability and locally high porosity and permeability;and(iv)by using the above-mentioned three methods,the lower limits of porosity and permeability are de-termined as 1.97%and 0.0090 mD,respectively.The study provides a reference for identifying effective reservoirs,determining net pays,and estimating GIP.

关 键 词：川中地区 茅口组 储集岩类型 储渗空间 物性特征 有效物性下限 

分 类 号：P618.13[天文地球—矿床学]