基于拓扑分析的疏松砂岩气藏储层结构和润湿特性评价新方法  

A new topology-based evaluation method for reservoir structure and wettability of unconsolidated sandstone gas reservoirs

作　　者：孙晨皓 李军[1,3] 董赛亮 邹嘉玲 SUN Chenhao;LI Jun;DONG Sailiang;ZOU Jialing(National Key Laboratory of Petroleum Resources and Engineering//China University of Petroleum-Beijing,Beijing 102249,China;College of Geosciences,China University of Petroleum-Beijing,Beijing 102249,China;China University of Petroleum-Beijing at Karamay,Karamay,Xinjiang 834000,China)

机构地区：[1]油气资源与工程全国重点实验室·中国石油大学(北京) [2]中国石油大学(北京)地球科学学院 [3]中国石油大学(北京)克拉玛依校区

出　　处：《天然气工业》2023年第10期94-102,共9页Natural Gas Industry

基　　金：国家自然科学基金项目“基于拓扑几何学的致密油藏跨尺度润湿机理研究”(编号:42102149);北京市自然科学基金项目“面向碳封存的深部咸水层多尺度润湿机理研究”(编号:3222038);中国石油大学(北京)拔尖人才项目“致密储层跨尺度润湿机理研究”(编号:2462021BJRC004)。

摘　　要：疏松砂岩气藏气水分布和运移关系复杂,储集岩孔隙结构特征、原位润湿特征和气水界面性质制约了天然气储量的有效动用,其中储层孔隙结构和润湿性的准确评价对气藏治水与高效开发具有重要意义。为了弥补传统评价方法在精度和尺度上的不足,结合持续拓扑分析和三维CT无损成像技术,精细表征了疏松砂岩气藏储层的孔隙结构,并应用拓扑几何学Gauss—Bonnet定理拓展了孔隙尺度润湿机理,创新了原位润湿性评价方法,系统研究了双相润湿特征对气水赋存分布规律的影响机制,最后提出了基于拓扑分析的疏松砂岩气藏储集岩特性评价新方法。研究结果表明:①持续拓扑分析结果全面且精细地表征了疏松砂岩储集空间的孔隙结构及其高孔隙度、高渗透率的物性特征,并验证了该方法的适用性;②基于拓扑几何学的润湿性评价新方法定量表征了储集岩的原位润湿性,且误差在6%以内,相较于传统方法,精度提高了约11%;③强水湿体系中气体普遍赋存于大孔,部分孤立的气泡赋存于小孔,油湿体系中地层水大多赋存于大孔且极易建立优势渗流通道,从而导致开发初期气藏产水现象的发生。结论认为,该新方法可快捷、准确地识别与表征岩石的孔隙结构与原位润湿性,对推动储层表征技术的进步,预测天然气在疏松砂岩气藏的运移能力及提高气藏的治水稳产效果具有重要的理论和工程意义。Unconsolidated sandstone gas reservoirs have complex gas and water distribution and migration relationships,and the effective production of their natural gas reserves is restricted by the pore structure characteristics and in-situ wetting behaviors of reservoir rocks and the properties of gas–water interface.Particularly,the accurate evaluation of reservoir pore structures and in-situ wettability is of great significance for the water control and efficient development of gas reservoirs.In order to overcome the shortcomings of traditional methods in accuracy and scale,this paper precisely characterizes the pore structures in unconsolidated gas reservoirs by using the persistent topology analysis and the 3D CT nondestructive imaging technology.Then,the wettability mechanism on the pore scale is expanded by applying the Gauss–Bonnet theorem of topology geometry,the in-situ wettability evaluation method is innovated,and the influential mechanisms of two-phase wetting behaviors on gas and water occurrence and distribution laws are systematically researched.Finally,a new method for evaluating reservoir characteristics of unconsolidated sand stone gas reservoirs based on topology analysis is proposed.And the following research results are obtained.First,the results of persistent topology analysis comprehensively and precisely characterize the pore structures and physical properties(high porosity and high permeability)of unconsolidated sandstone reservoirs,and verify the applicability of this method.Second,the new wettability evaluation method based on topology geometry can quantitatively characterize the in-situ wettability of reservoir rocks with an error less than 6%,and its accuracy is about 11%higher than that by the traditional method.Third,in a strong water-wet condition,gas generally exists in large pores,and a few isolated gas bubbles lie in small pores.In oil-wet condition,most of the formation water exists in large pores,so dominant flow pathways are formed quite easily,which leads to water breakthrough at

关 键 词：疏松砂岩 孔隙结构 润湿性 拓扑分析 物性评价 天然气藏 界面特性 多相渗流 

分 类 号：P618.13[天文地球—矿床学] TE37[天文地球—地质学]