一种二氧化碳驱油开发效果综合评价新方法

New Comprehensive Evaluation Method for Development Effect of CO_(2) Flooding

我国CO_(2)驱油技术正处于探索试验阶段,尚未形成系统的CO_(2)驱开发效果综合评价方法,目前已有方法评价体系中未考虑油藏条件、管理状况、效益状况、安全环保、气窜程度等因素,评价体系不完善,常用评价方法受人为因素影响较大,缺乏科学的理论依据,往往导致评判结果与矿场实际情况不符。针对这些问题,本文从特低渗透油藏条件出发,基于CO_(2)驱动态特征及开发效益等方面,引入混相系数、气油比、套管腐蚀速率、投入产出比、HSE测评等指标,建立了10大系统,共34个评价指标,建立了CO_(2)驱开发效果评价体系,利用隶属度区间分布计算方法和主客观组合赋权法,建立了评价模型。研究表明:2018年H区块综合评价结果 为“中”,结合评价结果进行分层注气、水气交替、转注、压裂,提升管理、优化投资等,截至目前,区块平均单井日产油量由1.2t上升到2.3t,投入产出比由1∶1.5提高到1∶2,地层压力提高0.8MPa。所建方法能够为CO_(2)驱油藏开发调整提供理论保障。

CO_(2) flooding technology in China is in the exploratory and experimental stage.The systematic evaluation method for the development effect of CO_(2) flooding has not yet been formed.At present,factors such as reservoir conditions,management status,benefit status,safety and environmental protection,gas channeling degree are not taken into account in the evaluation system of existing methods.The evaluation system is imperfect,and the commonly used evaluation methods are greatly influenced by human factors lacking scientific theoretical basis,which result in the evaluation result being inconsistent with the actual field situation.Aiming at these problems,10 major systems,including 34 indicators,are established by introducing miscibility coefficient,gas-oil ratio,casing corrosion rate,input-output ratio and HSE evaluation indicators in the extra-low permeability oil reservoirs based on dynamic characteristics and development effect of CO_(2) flooding.A system for evaluating the development effect of CO_(2) flooding is formed.Calculation method of membership interval distribution and subjective and objective combination weighting method are applied to the establishment of evaluation model.The evaluation results show that the comprehensive evaluation result of Block H in 2018 is "medium".Combined with the evaluation results,stratified gas injection,water-gas alternation,injection and fracturing are carried out to improve management mode and optimize investment.Up to now,the average daily oil production of single well in Block H has increased from 1.2t/d to 2.3t/d,the input-output ratio has increased from 1 ∶1.5 to 1∶2,and the formation pressure has increased by 0.8MPa.The method can provide technical support for the development planning of CO_(2) flooding reservoirs.