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水锁效应是在油气开发过程中,当钻井液、完井液等外来流体侵入储层后,造成近井壁处油气相渗透率降低的现象。水锁效应是影响油气井生产的主要因素,尤其是在低渗透储层,这种影响更显著。低渗透储层通常是指渗透率较低的砂岩储层,其他还有在一定次生改造条件下可以成为储层的泥岩、岩浆岩和变质岩等。油气层从打开直至枯竭的全过程中,不同类型的工作流体会改变地层原始平衡状态,使油气层的原始渗透性受到损害。研究水锁效应基本原理、实验方法、评价指标及其预测方法,对提高低渗透储集层的采收率具有重要意义。调研了目前水锁损害实验方法以及模拟预测等方面的研究进展,从实验的基本原理、常规分析方法、辅助指标以及水锁损害模拟与预测模型等方面,对水锁损害研究方法进行介绍。对岩心自吸以及驱替实验、蒸发作用的数学建模与计算、水锁指标的构建、水锁损害的计算机模拟、回归分析法、灰色预测法、神经网络法及灰色-神经网络预测法等相关研究成果进行总结,分析各实验方法的应用条件和不足。有助于理解现阶段水锁损害的研究方法,并为新方法的提出和应用提供基础。
Water lock effect is the phenomenon that when the external fluids such as drilling fluid and completion fluid intrude into the reservoir during the process of oil and gas development, the permeability of hydrocarbon near the wall is reduced. Water lock effect is the main factor affecting the production of oil and gas wells, especially in low permeability reservoirs, this effect is more pronounced. Low-permeability reservoirs usually refer to sandstone reservoirs with lower permeability. Others include mudstone, magmatic rocks and metamorphic rocks that can become reservoirs under some secondary reconstruction conditions. During the entire process of oil-gas formation from open to exhausted, different types of working fluids will change the original equilibrium state of the formation and damage the original permeability of the hydrocarbon-bearing layer. Studying the basic principles, experimental methods, evaluation indexes and prediction methods of water lock effect is of great significance to improve oil recovery of low permeability reservoirs. The research progress of the water lock damage experiment method and the simulation prediction are studied. The water lock damage research methods are introduced from the basic principles of the experiment, the routine analysis methods, the auxiliary indicators and the water lock damage simulation and prediction model. Self-priming and displacement test of core, mathematical modeling and calculation of evaporation, construction of water lock index, computer simulation of water lock damage, regression analysis, gray prediction, neural network and gray-neural network prediction The related research results are summarized, and the application conditions and deficiencies of each experimental method are analyzed. It helps to understand the research methods of water lock damage at the present stage and provide the foundation for the new method’s application and application.