注气开发低渗透油藏见气见效时间预报方法  

New Theory of Gas Emergence Time Prediction in Gas Flooding Tight Reservoirs

作　　者：王高峰[1] 

机构地区：[1]提高石油采收率国家重点实验室(中国石油勘探开发研究院),国家能源CO2驱油与埋存研发(实验)中心,北京100083

出　　处：《科学技术与工程》2014年第34期18-23,共6页Science Technology and Engineering

基　　金：国家科技重大专项(2011ZX05016)资助

摘　　要：气驱开发油藏见气时间预报油藏工程完备理论尚未见报道。首次提出应用完全非混相驱替、一次萃取和一次溶解膨胀三个步骤,即"三步近似法"简化真实气驱过程。引入"特征流管"概念研究波及区域完全非混相驱含气饱和度分布。结合相态理论和实验成果量化一次萃取和一次溶解引起的油藏流体膨胀。利用物质平衡原理和气驱增产倍数概念描述见气见效时的"油墙"规模。分别计算了见气见效时游离态、溶解态和成矿固化态三种赋存状态的注入气体占据的烃类孔隙体积,得到低渗透油藏见气见效时间预报普适理论模型。给出了CO2驱油藏见气时间计算简化公式,用于十个注气项目的平均相对误差为8.3%。发现见气见效时间对见气前的阶段地层压力及其接近最小混相压力的程度、注入气地下密度和和理论体积波及系数较为敏感。指出提高见气前的阶段地层压力和增加体积波及系数是延迟见气的两项基本技术对策。研究成果对编制气驱方案、把握注气动态并及时制定生产调整对策有重要指导意义。Understandings of gas flooding performances in various sandstone reservoirs have become complete gradually. Both gas drive experience and theoretical analysis show that the rapid increasing time of produced gas oil ratio,the decreasing time of comprehensive water cut and the arrival time of ‘oil bank＇frontier towards producers are intrinsic identity,which is named as gas emergence time. However,there is no good way to determine the size of miscible region and to predict gas floods performances. Difficulties in accurate complete description of the complexity of phase behavior,microcosmic gas displacement process,accurate measurement of three phases flow,and significantly reducing uncertainties of the geological models are so great that the prediction results of multiple component numerical simulation of gas flooding process are always unreliable especially in tight reservoirs. Therefore,it is necessary to develop effective reservoir engineering methods. Complete reservoir engineering theory of gas emergence time forecasting in gas flooding reservoirs has not been reported. In actual gas flooding process,seepage flow and phase change occur simultaneously. A new method called ‘three steps approximation＇is firstly proposed to simplify the real process of gas displacement and to facilitate reservoir engineering research,which involves absolute immiscible displacement（ AID） exclusive of phase change,one-time evaporation / extraction（ OTE） of middle weight hydrocarbon molecules from crude oil,and one-time dissolving of gas injected and reservoir liquids expansion（ OTDE）. Concept of representative stream tube（ RST） representing the average static and dynamic properties of sweeping volume is introduced to study gas saturation distribution in the AID process. OTE and OTDE process is quantified by employing theoretical and experimental results of phase behavior. The size of ‘oil bank＇at the time of gas emergence is described with the concept of oil production rate multiplier（ the ratio of gas f

关 键 词：气驱 见气时间 特征流管 完全非混相 萃取 溶解膨胀 油墙规模 三步近似法 

分 类 号：TE311[石油与天然气工程—油气田开发工程]