摘要
为了明确致密岩心在地层条件下孔隙度和渗透率与上覆压力的关系,利用CMS-300覆压测试系统、铸体薄片、扫描电镜等手段,分析了X233区致密油储层与A区超低渗储层岩心覆压孔渗特征。结果表明:(1)随着上覆压力增大,致密油储层岩心孔隙度呈减小趋势,减小的幅度较小,反映出加压作用造成的孔隙度损失率较小(RΦ=0.9);经过加压变化过程,岩心样品发生了线弹性变化;(2)随着上覆压力增大,致密油储层岩心渗透率呈减小趋势,减小的幅度较大,反映渗透率对压力有敏感性及压实作用造成的渗透率损失率较大(RK=0.19);(3)随着上覆压力增加,致密油储层覆压孔隙度和覆压渗透率与上覆压力均呈指函数递减关系;(4)经过加压变化,致密油储层渗透率与超低渗储层渗透率都与上覆压力呈指数关系;与超低渗储层相比,致密油储层经过长期的压实、胶结与溶蚀等作用,且软塑性变形物质含量相对较少,因此,压实作用对致密油储层造成的孔隙度损失率小、渗透率损失率大。该研究成果对于分析陇东地区致密油储量和油气田开发提供了一定基础数据。
In order to find out the relationship between the porosity and permeability of tight core and the overlying pressure under formation conditions the characteristics of overlying pressure porosity and permeability of tight oil reservoir in area X233 and ultra-low permeability reservoir in area A are analyzed by means of CMS-300 overlying pressure test system casting thin section as well as scanning electron microscope.The results show the followings:with the increase of overburden pressure(1)the core porosity shows a decreasing trend but a small change range reflecting a small loss rate of porosity caused by pressurization(RΦ=0.9);in addition,the core sample has approximately a linear elastic change through the pressurization process;(2)the core permeability of tight oil reser-voir shows a decreasing trend and the decreasing range is large,which indicates that the permeability is sensitive to pressure.The decreasing trend that the permeability shows,with a large change range,indicates a large permeability loss rate caused by compaction(RK=0.19);(3)the relationship between overburden porosity,overburden permeability and overburden pressure is exponential decline.Furthermore,both the permeability of tight oil reservoir and ultra-low permeability reservoir are exponentially related with overburden pressure through the pressurization.Compared with ultra-low permeability reservoir,the tight oil reservoir undergoes long-term compaction,cementation and dissolution;likewise,the content of soft plastic deformation material is relatively small.Accordingly,both the porosity loss rate and permeability loss rate caused by compaction are small.In conclusion,the research results provide some basic data for the analysis of tight oil reserves and the development of oil as well as gas fields in Longdong area.
作者
王楠
斯尚华
宋鹏
杨红梅
王新星
王洪君
WANG Nan;SI Shanghua;SONG Peng;YANG Hongmei;WANG Xinxing;WANG Hongjun(Exploration and Development Research Institute of PetroChina Changqing Oilfield Company,Xi'an 710000,China;National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,Xi'an 710000,China;Xi'an Shiyou University,Xi'an 710065,China;Changqing Oilfield Company Oil Production Plant NO.2,Qingyang 745100,China;Changqing Oilfield Company Oil Production Plant NO.5,Xi'an 710200,China)
出处
《青海大学学报》
2020年第2期96-102,共7页
Journal of Qinghai University
基金
陕西省基础研究计划项目(2019JM-055)。
关键词
长7
致密油
覆压孔隙度
覆压渗透率
陇东地区
Chang 7
tight oil
overburden porosity
overburden permeability
Longdong area
