摘要
库容量计算是地下储气库(以下简称储气库)建库地质方案设计的核心研究内容之一,油藏建库由于存在气油水三相渗流和复杂的气—油组分交换相行为,其库容形成机理与气藏建库具有显著差别。为此,基于多轮气驱、相平衡实验和数值模拟等研究,剖析了油藏建库库容形成机理及其影响因素,结合建库不同阶段储层流体分布及运移特征,提出了将建库油藏纵向划分为气驱纯油带、气驱水淹带/油水过渡带和纯水带3个不同区带,进行差异化计算库容量的新思路,并建立了以“有效储气孔隙体积”为核心,综合考虑不同流体区带注气微观驱替效率、宏观波及系数、剩余油二次饱和溶解及其性质变化等多相渗流和相行为的油藏建库库容量多因素预测数学模型和计算方法。研究结果表明:①油藏水驱后气驱改建储气库,微观气驱效率和宏观波及系数是影响油藏建库库容规模的主控因素;②剩余油二次饱和溶解及其体积收缩对库容规模具有一定的影响,原油挥发性越强、建库稳定剩余油越多,剩余油二次饱和溶解和原油性质变化对库容量影响越显著;③冀东油田堡古2挥发性油藏建库次生气顶自由气有效库容量为18.61×10^(8)m^(3),其中气—油组分交换相行为引起的建库稳定剩余油收缩增加库容量为2.81×10^(8)m^(3),贡献率为15.1%,自由气和剩余油二次饱和溶解总库容量为28.60×10^(8)m^(3)。结论认为,该方法在冀东油田堡古2号、南堡1号储气库进行了应用实践,所建立的油藏库容计算模型具有良好的应用效果,但由于油藏建库机理较气藏更为复杂,目前水淹区和纯油区的宏观波及系数和微观驱替效率以室内试验、数值模拟计算为主,高强度注采引发的气窜、气油水互锁等对库容的形成将产生较大影响,建库运行过程中需加强动态监测,实时修正数值模型,并建立合理的注气和排液技术界限,合理控制油气界面稳定扩展,提升达容达产效率。
Storage capacity calculation is one of the core research objectives in the geological scheme design of underground gas storage(hereinafter referred to as UGS)construction.Oil-reservoir UGSs are obviously different from gas-reservoir UGSs in the formation mechanism of storage capacity,for it has a gas–oil–water three-phase flow and complex gas–oil composition exchange phase behavior.Based on multi-cycle gas displacement,phase equilibrium experiment and numerical simulation,this paper analyzes the formation mechanisms and influential factors of storage capacity in oil-reservoir UGSs.Then,based on the distribution and migration characteristics of reservoir fluids in different stages of UGS construction,a new idea is proposed to vertically divide the oil reservoir to be rebuilt into UGS into three zones(i.e.,gas displaced pure oil zone,gas displaced water flooding zone/oil–water transition zone and pure water zone)for differential calculation of storage capacity.In addition,the multi-factor prediction mathematical model and calculation method of storage capacity in oil-reservoir UGSs are established.They take"effective gas storage pore volume"as the core,and comprehensively consider microscopic gas displacing efficiency,macroscopic coefficient,secondary saturation dissolution and property change of remaining oil,and other multiple-phase seepages and phase behaviors in different fluid zones.And the following research results are obtained.First,the storage capacity of the UGSs rebuilt from the oil reservoirs stimulated by gas flooding after water flooding is mainly controlled by microscopic gas displacement efficiency and macroscopic sweep coefficient.Second,the secondary saturation dissolution and volume shrinkage of the remaining oil have a certain impact on the storage capacity.The stronger the volatility of the crude oil and the more the stable remaining oil during UGS construction,the more significant the impact of the secondary saturation dissolution of the remaining oil and the change of crude oil properties on the storage capacity.Third,in the UGS rebuilt from the Jidong Pugu 2 volatile oil reservoir,the effective storage capacity contributed by the free gas of the secondary gas cap is 18.61×10^(8)m^(3),15.1%of which,i.e.,2.81×10^(8)m^(3),results from the shrinkage of the stable remaining oil during UGS construction caused by the gas–oil composition phase behavior.The total storage capacity contributed by free gas and secondary saturation dissolution of remaining oil is 28.60×10^(8)m^(3).In conclusion,this method has been practically applied in Pugu 2 and Nanpu 1 UGSs of the Jidong Oilfield,and the established calculation model of the storage capacity of oilreservoir UGSs presents remarkable application effects.However,the construction mechanism of oil-reservoir UGSs is more complicated than that of gas-reservoir UGSs,the macroscopic sweep coefficient and microscopic displacement efficient of flooded zones and pure oil zones are mainly the results of laboratory test and numerical simulation,and gas channeling and gas–oil–water interlock caused by high-intensity injection and production have a greater impact on the formation of storage capacity,so in the process of UGS construction and operation,it is necessary to strengthen dynamic monitoring,correct the numerical model in real time,and establish reasonable technological limit of gas injection and liquid drainage,so as to control the stable extension of oil–gas contact reasonably and improve the storage capacity expansion and production efficiency.
作者
高广亮
刘伟
李聪
孙彦春
杨智斌
何海燕
孙军昌
王皆明
张宪国
刘满仓
GAO Guangliang;LIU Wei;LI Cong;SUN Yanchun;YANG Zhibin;HE Haiyan;SUN Junchang;WANG Jieming;ZHANG Xianguo;LIU Mancang(State Key Laboratory of Deep Oil and Gas//China University of Petroleum-East China,Tangshan,Hebei 063000,China;PetroChina Jidong Oilfield Company,Tangshan,Hebei 063000,China;Bohai Rim Energy Research Institute,Northeast Petroleum University,Qinhuangdao,Hebei 066200,China;Underground Gas Storage Research Center,PetroChina Research Institute of Petroleum Exploration&Development,Langfang,Hebei 065007,China;National Energy Underground Gas Storage R&D Center,Langfang,Hebei 065007,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2023年第10期132-140,共9页
Natural Gas Industry
基金
中国石油前瞻性基础性科技项目“油藏建库库容形成规律与储气库参数指标设计方法”(编号:2022DJ8302)。
关键词
海上砂岩油藏
库容量
微观气驱效率
宏观波及系数
气油相行为
有效储气孔隙体积
原油收缩
Oil reservoir
Storage capacity
Microscopic gas displacing efficiency
Macroscopic sweep coefficient
Gas-oil Phase behavior
Effective gas storage pore volume
Crude oil shrinkage
