低渗油藏CO2驱特征曲线理论推导及应用

摘要

基于低渗油藏CO2驱过程中CO2与原油渗流符合幂指数规律的假设,在甲型水驱特征曲线理论基础上,推导了低渗油藏CO2驱特征曲线,建立了CO2拟含气率与采出程度关系式,形成低渗油藏CO2驱地质储量、可采储量和采收率等指标的预测方法.低渗油藏CO2驱特征曲线形式表明,修正后的累计CO2产量与累计产油量呈半对数直线关系.现场生产实例应用表明,CO2驱特征曲线能较好地预测低渗油藏CO2驱的可采储量及采收率等动态指标,对区块开发评价具有指导意义.%Based on the theory of Type-A waterflooding characteristic curves,because the percolations of CO2 and oil during CO2 flooding in low permeability reservoirs are in accordance with the power exponent law,the paper derives the CO2 flooding characteristic curves for low permeability reservoirs,establishes a relationship between quasi-content of CO2 and recovery percent of reserves and obtains a series of methods to predict recoverable reserves and recovery factor of CO2 flooding in low permeability reservoirs.The characteristic curves of CO2 flooding in low permeability reservoirs show that the modified relationship between cumulative CO2 production and cumulative oil production is semi-logarithmic.The field application indicates that the dynamic indices such as recoverable reserves and recovery factor by CO2 flooding in low permeability reservoirs can be better predicted with the characteristic curves,which is helpful for block development evaluation.