低渗油藏水平井注水合理井距研究

摘要

Using Injection-production system of horizontal wells in low permeability reservoirs by water drive process can solve many prob- lems from vertical wells, such as small well spacing and limited well-controlling reserves, etc., hence obtaining good economic benefits. At present, the mature method for calculation of reasonable injection-production well spacing is not yet found for such a kind of reservoirs by adopting horizontal well to run water flood development. Based on oil-water two-phase flow, non-piston drive and oil production, this paper proposes a new method for determination of such a reasonable well spacing by using the two-phase flow mathematical expression, regarding the sum of water flooding front and injector distance and well drainage pressure swept distance as basis of the reasonable well spacing by mathematical derivation. The case study shows that the relationship between the reasonable well spacing and the permeability is well simu- lated by power function, and the horizontal well spacing is much longer than the vertical well spacing.%低渗油藏直井注采井距小、单井控制储量小，采用水平井注采系统可较好解决这些问题，获得较好的经济效益。目前低渗油藏水平井注水合理注采井距，尚未有较成熟的计算方法。在全面考虑油水两相流、非活塞驱替及产量等影响因素基础上，利用两相流数学表达，经数学推导将水驱前缘与注水井距离和油井泄油压力波及距离之和作为合理井距的依据，为确定低渗透油藏水平井合理井距提供了一种新方法。通过实例计算表明，水平井注采井距与渗透率呈近似幂函数的关系，且水平井注采井距较直井大许多。