特低渗油藏水平井与直井注采系统差异研究

特低渗油藏直井开发注采井距小,单井控制储量有限,但采用水平井注采系统可较好地解决上述问题,从而获得较好的经济效益。文中全面考虑油水两相流、非活塞驱替及产量等影响因素,利用两相流数学表达式,将水驱前缘与油井泄油压力波及距离之和作为设计注采井距的依据,分别研究了特低渗油藏直井与水平井极限注采井距与物性的关系,深入剖析了2种注采系统开发特低渗油藏的差异。实例分析表明,2种注采系统的注采井距与渗透率近似呈幂函数关系,且水平井注采井距是直井的2～3倍,有效解决了直井注采井距小的问题;进一步证实了水平井井间渗流为线性渗流,比直井的注采系统更有利,从而为采用水平井开采特低渗油藏提供了理论基础。

Study on difference between production-injection systems of horizontal and vertical wells in extra-low permeability reservoir

In the extra-low permeability reservoir,the well spacing of production-injection in vertical well development is small and the control reserves of single well are limited.But the problem can be solved and good economic benefit can be obtained using the production-injection systems of horizontal well system.The relationship between limit injection-production well spacing and physical property of vertical and horizontal wells is studied respectively and the difference of vertical and horizontal injection production system is analyzed considering the factors of oil and water two phase flow,non-piston displacement and production fully,using mathematical expression and taking the sum of flooding front and oil drainage distance as the well spacing of production-injection.The example analysis shows that the injection-production well spacing of two production-injection systems is a power function relationship to the permeability and the injection-production well spacing of horizontal well is 2 to 3 times of vertical well,which solves small spacing problem.The theory of linear flooding is verified between horizontals and it is easier to establish injection-production systems through comparing the pressure drop profile of two injection-production systems,which can provide theoretical basis for horizontal well development in the extra-low permeability reservoir.