非稳态原位热解扶余油页岩热-流耦合模拟

Thermal-Fluid Coupling Simulation on In-situ Unsteady Pyrolysis of Fuyu Oil Shale

采用热-流耦合分析模式,对水力压裂之后扶余油页岩储层的传热导流渗透能力进行数值模拟,发现流体主要沿油页岩层理方向形成地裂隙流出,但是随温度的增加,孔隙度增大也会有少许流体从油页岩的原生孔隙流出,渗流场压力在同一截面自裂隙垂直于油页岩层理向两端呈现下降趋势;流体对油页岩地层热量的传导主要是沿裂隙方向进行.加热时间增长,裂隙两侧油页岩裂解,孔隙度增加,氮气向油页岩储层的扩散速度也得到了提高,加热至40 d之后,裂隙周围油页岩首先达到裂解温度,加热至60~100 d,油页岩层的平均温度自500 K提升至650 K,整个油页岩能够被有效热解.

Numerical simulation on heat transfer and permeability of Fuyu oil shale reservoir after hydraulic fracturing was carried out by using thermal-fluid coupling analysis model. It is found that the fluid mainly flows out of the fracture along the oil shale bedding direction. However, as the temperature increases, the porosity increases and a little fluid flows out of the primary pores of the oil shale. The seepage field pressure shows a downward trend in the same section from the fracture perpendicular to the oil shale bedding. The heat conduction of fluid to oil shale formation was mainly in the direction of fracture. As the heating time increases, the oil shale cracks on both sides of the fissure, and with the porosity increase, the diffusion rate of nitrogen to the oil shale reservoir is also improved. After 40 days of heating, the oil shale around the fracture first reaches the cracking temperature. Between 60 and 100 days of heating, the average temperature of oil shale rises from 500 K to 650 K, and the whole oil shale can be effectively cracked.