致密/页岩油藏注气吞吐多测点三维物理模拟装置设计

Design of Multi-point Three-dimensional Physical Simulation Apparatus for Gas Injection Huff and Puff in Tight and Shale Oil Reservoir

结合致密/页岩油藏注气吞吐提高采收率技术,设计了一种适用于致密/页岩油藏注气吞吐的多测点三维物理模拟模型,开发了高温高压水平井注气吞吐三维物理模拟实验方法,并开展了高温高压水平井CO_(2)吞吐三维物理模拟实验。在焖井压力20 MPa条件下,可将焖井过程分为压差驱动、扩散驱动和溶解驱动3个阶段。压差驱动阶段CO_(2)主要依靠渗流作用在地层中运移,焖井压力下降较快,平均下降速率为0.57 MPa/h;扩散驱动阶段压力呈线性下降,下降较为平缓,平均下降速率为0.16 MPa/h,CO_(2)扩散起主导作用;溶解驱动阶段压力基本趋于15.2 MPa的稳定值,流体流动明显减弱,CO_(2)逐步溶解在原油中。此外,当焖井过程结束进入生产阶段后,CO_(2)主要发挥了携带驱油、膨胀原油等作用机理。

Combined with the enhanced oil recovery technology of gas injection huff and puff in tight/shale reservoir,a multi-point three-dimensional physical simulation model suitable for gas injection huff and puff in tight/shale reservoir is designed,a three-dimensional physical simulation experimental method for gas injection huff and puff in high temperature and high pressure horizontal wells is established,and the three-dimensional physical simulation experiment of CO_(2) huff and puff in high temperature and high pressure horizontal wells is carried out.Under the condition of 20 MPa soaking pressure,the soaking process can be divided into three stages,i.e.,differential pressure drive,diffusion drive and dissolution drive.In the stage of differential pressure drive,CO_(2) mainly flows in the formation through seepage,and the soaking pressure drops rapidly with an average rate of 0.57 MPa/h.During the stage of diffusion drive,the pressure decreases linearly and gently,with an average rate of 0.16 MPa/h,and CO_(2) diffusion plays a leading role.For the stage of dissolution drive,the pressure basically tends to a stable value of 15.2 MPa,the fluid flow is significantly reduced,and CO_(2) gradually dissolves in crude oil.In addition,when the soaking process is finished and the production stage is entered,CO_(2) mainly plays a role in carrying oil displacement and expanding crude oil.