低渗砂岩油藏水流优势通道形成原因综述

A Review of the Reasons for the Formation of Water Flow Advantage Seepage Channels in Low-Permeability Sandstone Reservoirs

摘要: 我国低渗砂岩油藏分布广泛，具有渗透性差、非均质性严重、储层敏感性强等特点，在注水开发后期会出现差异渗流现象，使得水流逐渐集中在某些区域，形成水流优势通道，造成注入液利用率低、层内及层间矛盾加剧、水驱效率降低等现象，严重影响油田注水开发效益。目前，针对优势渗流通道形成机理问题，各大油田相关研究机构也开展了油田地质等系列研究。综合各油田优势渗流通道类型，可分为三种：一是层间矛盾形成的优势渗流通道，二是层内矛盾形成的高渗透条带，三是储层平面非均质性、注采不平衡形成的优势渗流通道。现有研究表明，优势通道形成的影响因素分为外在条件和内在因素，外在条件包括注入速度、累计注采量、注采强度、注入压差等控制条件以及注采工艺等工艺因素，内在因素包括油藏自身的胶结程度、沉积环境等自身物性条件和流体特征。

Abstract: Low-permeability sandstone reservoirs are widely distributed in China, characterized by poor permeability, severe heterogeneity, and high reservoir sensitivity. During the later stages of waterflooding development, differential flow phenomena emerge, causing water flow to gradually concentrate in certain areas and form dominant flow pathways. This results in low injection fluid utilization, intensified intra- and inter-layer contradictions, and reduced waterflood efficiency, severely impacting the benefits of waterflooding development in oilfields. Currently, major oilfield research institutions have conducted geological studies to investigate the formation mechanisms of dominant flow pathways. Based on observations across various fields, these pathways can be categorized into three types: 1) Dominant flow pathways formed by inter-layer conflicts; 2) High-permeability zones created by intra-layer conflicts; 3) Dominant flow pathways arising from horizontal reservoir heterogeneity and injection-production imbalances. Existing research indicates that factors influencing dominant flow path formation can be categorized into external conditions and intrinsic factors. External conditions include control parameters such as injection rate, cumulative injection-production volume, injection-production intensity, and injection pressure differential, as well as process factors like injection-production techniques. Intrinsic factors encompass reservoir-specific properties such as cementation degree and depositional environment, along with fluid characteristics.