石油科学通报2025，Vol.10Issue(6)：1130-1151,22.DOI:10.3969/j.issn.2096-1693.2025.01.027
玛湖1井区上乌尔禾组致密砾岩油藏流体赋存控制因素及分级储量表征
Controls on fluid occurrence and classified reserves characterization in tight conglomerate reservoirs of Upper Urho Formation in Mahu Well Block 1
摘要
Abstract
The tight conglomerate reservoir in the Junggar Basin exhibit complex multi-scale pore-throat structures,which obscure the dominant controls on fluid occurrence,hinder reservoir classification,and complicate the quantitative evaluation of graded reserves.To clarify the relationship between microscopic pore-throat characteristics and fluid occurrence states and achieve effective evaluation of highly heterogeneous tight conglomerate reservoirs,this study takes the Upper Urho Formation(P3w)in the CO2 flooding pilot area of the Mahu 1 well block as an example,conducting comprehensive workflow of"pore-throat structure-fluid occurrence-reservoir classification-graded reserves".Integrating methods including cast thin sections,high-pressure mercury intrusion,and nuclear magnetic resonance(NMR)logging were integrated to characterize the lithome-chanical properties and pore-throat structure parameters of different sub-layers within the main reservoir interval.Grey relational analysis further identified movable-to-total porosity(weight 0.913)and clay mineral content(weight 0.805)as the key factors controlling effective oil saturation.Based on NMR T2 spectral morphology,three-component index,IB value,and permeability,a classification standard dividing the reservoir into three types(Ⅰ～Ⅲ)was established,A methodology for calculating tiered pore-volume reserves was proposed,achieving a systematic evaluation from pore-throat structure to classified reserves.Results indicate that in the main producing interval P3w22,the lower sublayer exhibits significantly better reservoir quality than the upper.The lower section has a micron-scale pore proportion of 25.48%,an average permeability of 5.59 mD,and an effective oil saturation 15%～20%higher than the upper section.Nano-scale pores(<100 nm)represent the dominant storage space in the pilot area,containing reserves of 784.3 thousand tons(61.7%of the total).From the perspective of reservoir classification,type Ⅰreservoirs,with the highest proportion of micron-scale pores(25.48%)and excellent oil-bearing capacity.Type II reservoirs show reduced micron-scale pores and moderate oil-bearing capacity;Type III reservoirs suffer from poor oil retention due to strong confinement by nanopores.The results of this study reveal the controlling factors of fluid distribution,establish a classification standard and tiered reserve characterization system for tight conglomerate reservoirs constrained by pore-throat structures,and provide theoretical support and technical support for the optimal selection of CO2 flooding target zones and the identification of"sweet spots"in the Mahu conglomerate oilfield.关键词
致密砾岩储层/孔喉结构/流体赋存规律/核磁共振测井/分级储量Key words
tight conglomerate reservoir/pore-throat structure/fluid occurrence characteristics/NMR logging/graded reserves分类
能源科技引用本文复制引用
ZHANG Xuyang,LYU Bingchen,LI Qing,SONG Zhaojie,YUE Dali,FANG Yuxiang,LI Zhe,LIU Xiyu,WANG Jiaqi..玛湖1井区上乌尔禾组致密砾岩油藏流体赋存控制因素及分级储量表征[J].石油科学通报,2025,10(6):1130-1151,22.基金项目
国家科技重大专项"CO2驱大幅度提高采收率与长期封存技术"(2024ZD1406601)、国家科技重大专项"砾岩油藏精细分类与CO2驱适应性评价"(2025ZD1408401)、中国石油新疆油田公司科技重大专项课题"准噶尔盆地CO2驱地质油藏工程研究与现场试验"(2024XJZX0801)、国家自然科学基金项目"坳陷湖盆洪水型湖相重力流沉积演化机理及差异构型模式"(42272186)联合资助 （2024ZD1406601）
