注CO2解堵后注干气提高采收率技术研究——以中原油田某区块凝析气藏为例  

EOR technology by dry gas injection after plugging removing by CO2 huff and puff:A case study of condensate gas reservoir in a block of Zhongyuan Oilfield

作　　者：杨雪 YANG Xue(Research Institute of Exploration and Development,Sinopec Zhongyuan Oilfield Company,Puyang,Henan 457000,China)

机构地区：[1]中国石化中原油田分公司勘探开发研究院,河南濮阳457000

出　　处：《油气藏评价与开发》2020年第3期75-79,共5页Petroleum Reservoir Evaluation and Development

基　　金：国家高技术研究发展计划(863计划)项目“二氧化碳提高石油采收率与封存关键技术研究”(2009AA063406)。

摘　　要：为深化研究中原油田某区块凝析气藏提高采收率效果,以中原油田某区块沙三下低孔低渗凝析气藏为例,基于物质平衡方程和状态方程的理论支撑,通过PVT相态、物理模拟等室内实验,揭示了该气藏的衰竭开发规律,对该气藏低产无产原因深度剖析,认清目前现状。首次提出符合该区块凝析气藏地质特征的近井地带双向(产转注+生产井)解堵后注干气保压开采提高采收率开发方式,分别对注入端和采出端的天然岩心开展了注CO2解堵物理模拟实验,解堵后渗透率恢复分别为60.44%、63.15%,表明了注CO2解堵效果良好,在解堵的基础上,开展注干气保压岩心驱替实验。研究结果表明,凝析气藏一开始在原始地层压力41.19 MPa下注干气保压开采,凝析油采收率可达91.41%;衰竭至堵塞压力21.14 MPa再进行注干气保压开采,凝析油的采收率为44.28%。通过研究进一步明确了开发过程中因近井地带压力低于露点压力造成油水乳化堵塞的地层物理模型,为中原油田低渗致密凝析气藏的效益开发提供了技术支持。In order to further study the EOR effect of condensate gas reservoir in Zhongyuan Oilfield,the lower third member of Shahejie Formation of a block is taken as an example.Based on the theoretical support of material balance equation and state equation,laboratory experiments such as PVT phase state and physical simulation are carried out to reveal the development rule and deeply analyze the reasons of low production,even no production,of this gas reservoir,so as to recognizes the current situation.For the first time,a two-way EOR method by dry gas injection with pressure maintaining after plugging removing near wellbore area conforming to the geological characteristics of the condensate gas reservoir in this block is proposed.Physical simulation experiments of plugging removing by CO2 flooding for natural cores at injection end and extraction end are conducted respectively.The corresponding permeability after plugging removing is 60.44%and 63.15%,showing that the effect of plugging removing by CO2 injection is good.On this basis,experiment of core displacement with dry gas injection is conducted with the result that at the beginning,dry gas injection with pressure maintaining under the original formation pressure of 41.19 MPa for condensate gas reservoir can make the condensate oil recovery ratio up to 91.41%;when the pressure decline to the plugging pressure of 21.14 MPa,using this method again,the recovery ratio can be 44.28%.By the researches,the formation physical model of oil-water emulsification plugging,because that the near wellbore area pressure is lower than the dew point pressure in the development process,is further clarified,providing technical support for the benefit development of low permeability tight condensate gas reservoir in Zhongyuan Oilfield.

关 键 词：近井地带 凝析气藏 低渗 流体模型 提高采收率 

分 类 号：TE349[石油与天然气工程—油气田开发工程]