四川盆地二叠系—三叠系碳酸盐岩核磁共振实验测量及分析  

NMR experimental measurement and analysis of Permian-Triassic carbonate rocks in Sichuan Basin

作　　者：冯庆付[1] 翟秀芬[1] 冯周[1] 刘朱睿鸷 刘英明[1] Feng Qingfu;Zhai Xiufen;Feng Zhou;Liuzhu Ruizhi;Liu Yingming(PetroChina Research Institute of Exploration&Development)

机构地区：[1]中国石油勘探开发研究院

出　　处：《中国石油勘探》2020年第3期167-174,共8页China Petroleum Exploration

基　　金：国家科技重大专项“下古生界—前寒武系碳酸盐岩油气成藏规律、关键技术及目标评价”(2016ZX05004)。

摘　　要：碳酸盐岩储层类型多样,基质孔隙度普遍偏低,储层缝洞发育,孔隙结构复杂。孔隙结构及物性是储层和含油气评价的关键因素。为了研究孔隙结构的特征,针对四川盆地三叠系雷口坡组白云岩、二叠系茅口组致密石灰岩两类碳酸盐岩岩心等共计45块柱塞样品开展了常规孔渗、岩电实验、核磁共振等测量,从多角度分析了岩心样品的孔隙类型及在储层中的孔隙结构分布规律。研究结果表明,对于雷口坡组白云岩储层,整体岩心核磁T 2谱呈现明显的单峰、双峰、三峰特征,表明岩心存在三重孔隙介质(基质孔隙、裂缝、溶蚀孔洞),孔隙结构非均质性强,整体物性较差。致密石灰岩核磁共振测量表明,T 2谱呈现显著的双峰形态,储集空间为基质晶间孔及溶蚀孔,且不同岩心T 2谱左边峰值基本稳定0.1ms左右,表明孔隙尺寸比雷口坡组白云岩小。采用SDR模型反演的核磁共振渗透率与气测法测量的渗透率最大绝对误差为0.31mD,一致性较好。同时,核磁共振测量结果也可以在一定程度上反映泥质含量,泥质含量较高的岩心,核磁共振T 2谱前端信号很强,分布宽度也较大,而且核磁共振孔隙度通常大于气测孔隙度。文章所提供的实验测量及分析方法对于四川盆地碳酸盐岩缝洞储层具有普遍适用性。There are various types of carbonate reservoirs,with generally low matrix porosity,well developed fractures and cavities,and complex pore structure.Pore structure and physical properties are the key factors for evaluation of reservoir and oil and gas-bearing properties.In order to study the pore types of core samples and the distribution laws of pore structure in the reservoir from multiple aspects,a total of 45 core plugs,sampled from dolomite of the Triassic Leikoupo Formation and tight limestone of the Lower Permian Maokou Formation in the Sichuan Basin,were tested for conventional porosity and permeability,rock-electrical experiment and Nuclear Magnetic Resonance.The results show that,for the dolomite reservoir of the Leikoupo Formation,the overall NMR T 2 spectrum of the core samples shows characteristics of obvious single-peak,double-peak and triplepeak,indicating that there is triple-porous-media in the cores(matrix pores,fractures and dissolution vugs),the pore structure is of strong heterogeneity,and the overall physical properties are poor.NMR measurements of tight limestones show that T 2 spectrum presents a significant“double peak”shape.The reservoir space is matrix intercrystalline pores and dissolution pores.The left peak of T 2 spectrum of different cores is basically stable at about 0.1ms,indicating that the pore size is smaller than that of dolomite in the Leikoupo Formation.The maximum absolute error between NMR permeability inverted by SDR model and permeability measured by gas measurement is 0.31mD,which shows good consistency.Meanwhile,the NMR results can also reflect shale content to a certain extent.For cores with higher shale content,the front-end signal of NMR T 2 spectrum is strong,the distribution width is large,and the NMR porosity is usually larger than gas porosity.The experimental measurement and analysis methods in this paper are generally applicable to carbonate fracture-cavity reservoirs in the Sichuan Basin.

关 键 词：碳酸盐岩 核磁共振 孔隙结构 孔隙度 渗透率 SDR模型 

分 类 号：TE112.23[石油与天然气工程—油气勘探]