裂缝性稠油油藏动态渗吸实验研究

渗吸是指一种润湿相流体在多孔介质中置换出另一种流体的过程,对于裂缝性油藏来说,渗吸是其重要的采油机理。为了研究动态渗吸的作用机理和效果,通过室内物理模拟实验研究了裂缝性稠油油藏动态渗吸的作用效果。结果表明:裂缝宽度对渗吸效果影响显著,裂缝宽度越大,渗吸效果越好;端面封堵减少了岩心与注入流体的接触面积,渗吸的接触面积减小,导致渗吸效果变差,渗吸采收率及速度都降低;原油黏度会对渗吸效果产生影响,原油黏度增大,渗流阻力增大,导致渗吸效果差,当温度升高至90℃时,原油黏度降低,渗吸阻力小,采出程度增大;注入速度也会对渗吸效果产生影响,存在最优值,0. 5 m L/min的速度注入时动态渗吸的采收率最高;在动态渗吸实验中,传统的静态渗吸无因次标度模型也能够较好的标度动态渗吸数据,因此采用标度模型预测裂缝性稠油油藏的渗吸采收率也是合理、可行的。由此可见,动态渗吸采油能够充分利用裂缝和岩石基质之间渗透率的差异,将岩石基质中的原油采出,增大原油采收率,改善开采效果。

Experimental Study on Dynamic Imbibition of Fractured Heavy Oil Reservoirs

Imbibition is the process where a wetting phase fluid displaces another fluid in porous media. For fractured reservoirs, imbibition effect is an important mechanism for oil recovery. In order to investigate the mecha-nism and effect of dynamic imbibition, this paper investigates the exploiting effect of dynamic imbibition in fractured heavy oil reservoirs according to indoor physical simulation experiments. The results show that the fracture width has a significant effect on the imbibition effect, and the larger the fracture width, the better the imbibition effect, and the end face sealing reduces contact area between the core and injected fluid, so the contact area of the imbibition is decreased, resulting in poor imbibition effect and the lower imbibition recovery and velocity, in addition, the viscosity of crude oil will affect the osmotic effect. when increasing viscosity of crude oil, the resistance of seepage increases, resulting in poor imbibition effect. While the temperature rises to 90 °C, the viscosity of crude oil decreases, and the seepage resistance become smaller causing the degree of recovery increases; the injection rates also have an effect on the dynamic imbibition effect, therefore, there is an optimum value. the dynamic imbibition rate is the highest when injected at a rate of 0.5 ml/min. In the dynamic imbibition experiment, the traditional static imbibition dimensionless scale model can better scale dynamic infiltration data. Furthermore, it is reasonable and feasible to use the scale model to predict the seepage recovery of fractured heavy oil reservoirs. Most of all, it can be seen that dynamic imbibition makes full use of the difference in permeability between fractures and matrix, and the crude oil in matrix is recovered, which increases oil recovery and improves exploiting efficiency.