稠油油藏水平井井筒压降规律研究

Law of pressure drop along the horizontal wellbore in heavy oil reservoir

水平井技术已在稠油油藏开发过程中广泛运用,但因稠油黏度较大,水平井井筒压降已成为产能研究过程中不可忽视的问题。基于常规水平井产能理论,利用Joshi提出的方法将水平井三维渗流场简化为2个二维渗流场,运用保角变换方法以及等值渗流阻力法得到稠油油藏水平井地层渗流模型,同时考虑井筒变质量流动,建立了地层渗流与水平井井筒管流的耦合模型。实例分析表明,井筒压降使得水平井的无阻流量减小了7.7%,且稠油油藏水平井井筒压降远远大于常规油藏水平井井筒压降。敏感性分析表明,随着水平段长度、幂律指数以及油层厚度的逐渐增大,井筒压降逐渐增大,而随着井筒半径的逐渐增大,井筒压降则逐渐减小。本次研究为稠油油藏水平井井筒压降规律的研究提供了新的思路。

Horizontal well technology had been widely used in developing heavy oil reservoir. But for the high viscosity of heavy oil, the pressure drop along the horizontal wellbore had been a problem that can not be ignored in studying the productivity of horizontal well. Based on the productivity analysis theory of conventional horizontal well, this paper used the method put forward by Joshi to divide the three-dimensional seepage field into two two-dimension seepage fields, applied the conformal mapping method and law of equivalent percolation resistance to get the flow model in porous media of horizontal well in heavy reservoir, and considering the variable mass flow along the horizontal wellbore, built the coupling model between reservoir and wellbore. Case study shows that the pressure drop along the horizontal wellbore makes the absolute open flow decreased by 7.7%, moreover the value of pressure drop in the horizontal wellbore in heavy reservoir is far greater than that in conventional reservoirs. Sensibility analysis indicates that as the increasing of horizontal well length, power law index and reservoir thickness, the pressure drop along the wellbore also increases, while as the increasing of wellbore radius, the pressure drop decreases. This study can offer a new idea to research the law of pressure drop in the horizontal wellbore in heavy reservoir.