分级构型约束低渗相对优质储层预测技术及其应用

Prediction Method and Its Application of Relative High-Quality Reservoir Distribution in Low-Permeability Reservoir Dominated by Hierarchical Architecture

扇三角洲前缘水下分流河道是油田L1V油组主要储层,具有砂体厚度薄、非均质性强、低孔低渗的特征.针对常规优势沉积相带分析很难解决油田开发生产面临部分注水区块受效性不明,水驱波及范围有限等问题,提出一种分级构型约束低渗相对优质储层预测方法,该方法首先基于优化地震数据采用数学形态学方法开展储层内部构型边界检测和分类,并开展不同级次的储层构型分析;其次,以构型为约束运用神经网络聚类方法落实各复合河道优势沉积相带展布;最后,综合优势沉积相带及表征河道砂体连通性的构型边界优选研究区低渗相对优质储层发育区域.结果表明:(1)L1V油组发育断层(Ⅰ)、复合河道(Ⅱ)、单河道带(Ⅲ)三大类构型边界,其中,单河道带类(Ⅲ)可进一步划分为3种次一级边界,各构型边界具有不同的砂体连通性和地震反射特征;(2)L1V油组共发育3期近SN向展布的复合河道,即Channel-1、Channel-2、Channel-3,且各复合河道主要发育水下分流河道、水下分流河道间及、水下天然堤等沉积微相;(3)综合优势沉积相带(水下分流河道)展布及储层构型边界特征,预测了L1V油组各复合河道2类优质储层的平面展布.该方法能够提高低渗相对优质储层预测精度,指导井间砂体连通性及剩余油潜力分析,进而有效规避油田开发综合调整阶段开发风险,提高经济效益.

Underwater distributary channel sand body of fan deltaic front,the main reservoir for L1V oil group in K oil field,characterized by thin sand body,strong heterogeneity,low porosity and low permeability.At present,there are some problems in the oilfield development and production,such as slow diffusion of injected water and difficulty in energy supplement,unclear effectiveness of some water injection in some blocks,and limited scope of water flooding and so on.It's difficult to solve these problems just based on traditional Predominant sedimentary facies anlysis,especially to the low permeability reservoir.In this paper,one method was proposed to predict relatively high quality distribution in low permeability reservoirs dominated by different levels of architecture.Firstly,Based on optimized seismic data,the internal reservoir architecture boundaries are detected and classified,adopting mathematical morphology analysis method.Besides,different levels of reservoir architecture are analyzed in L1V oil formation.Secondly,constrained by composite channel reservoir architecture analysis,the distribution of dominant sedimentary facies belt for Channl-1 and Channel-2 are researched in L1V oil group,applying neural network clustering method.Finally,combined with dominant sedimentary facies belt and channel architecture boundary,which characterizes the connectivity of single stage channel sand body,relatively high quality reservoirs for low permeability reservoirs in the study area are optimized.The result shows that 1) for L1V oil formation,reservoir architecture boundaries are divided into 3 categories and 5 subcategories,including fault,composite channel and single channel belt,with different characteristics in sand body connectivity and seismic reflection;2) it develops three composite channel in L1V oil formation,including Channel-1,Channel-2,Channel-3 with near N-S trending.Besides,sedimentary microfacies for each composite channel includes underwater distributary channel,inter-channel and levee.Among them,fan delta front underwater distributary channel is a high-quality reservoir facies belt with pretty porosity and permeability;3) Based on the dominant sedimentary facies belt,combined with the reservoir architecture boundary characteristics,high-quality reservoirs for composite channel in the L1V oil group can be divided into two types.The method in this paper can improve the prediction accuracy of high quality reservoir in low-permeability reservoirs and guide inter well sand body connectivity and remaining oil potential area analysis.That will be beneficial to effectively avoid development risk in the oilfield development comprehensive adjustment stage and improve the economic benefits.