水驱油田合理注采压力系统

Rational injection-production pressure system in water-drive oilfields

合理注采压力系统优化研究是开发水驱油田关键环节之一。以往采用的算法均存在缺陷:1"吸水、产液指数法"未考虑注采不平衡问题、油水密度差异及体积系数;2"吸水、产液指数及注采比法"未考虑油水密度差异及体积系数;3"吸水、产液指数比及注采压差法"不具有理论和实际意义;4"考虑单井及地层压力变化法"未考虑注水井启动压力、采油井启动压力对油田开发效果的影响。为解决上述问题,基于水驱油田注采压力剖面,提出了优化研究水驱油田注采压力系统的新方法。与以往的算法相比,新方法综合考虑了注采不平衡、油水密度差异、体积系数、注水井启动压力、采油井启动压力梯度等方面的影响因素。结果显示,新方法可适用于水驱油田任何油藏类型、任何油层压力分布状况条件下的合理注采压力系统参数计算。运用新方法对胜坨油田胜一区沙河街组二段1—3砂组油藏进行了合理注采压力系统参数计算,得出了该油藏合理油、水井数比为1.42,合理地层压力保持水平为17.29 MPa,此时合理采液量为14 572.41 m3/d,比调整前增加12 452.41 m3/d,合理注水量为15 906.88 m3/d,比调整前增注13 566.88 m3/d,提液增注效果显著。研究结果表明,新方法具有较强的适用性和应用前景。

Optimization of rational injection-production pressure system is a key part of developing water flooding oilfield.However,the methods widely used previously have certain disadvantages. The water-absorption and fluid productivity index method does not take into consideration factors such as the imbalance between injection and production fluids,density difference between oil and water,and their volume factors. The method of‘water absorption and fluid productivity index and injection-production ratio＇ignores density difference between oil and water and volume factor. The method of‘index ratio of water-absorption to fluid-productivity and pressure difference between injection and production well＇has no theoretical and practical significances. The method of‘considering single well and reservoir pressure variations pays no attention to the influences of start-up pressure of water injection well and start-up pressure of production well on oilfield development effects. To solve the above-mentioned problems,a new approach to optimize the injection-production pressure system in water flooding oilfield was proposed based on the pressure profile of injection-production. Compared with the previous ones,the new method is comprehensive,taking into account such factors as injection-production imbalance,density difference between oil and water,volume factor,start-up pressure gradient of injection wells and start-up pressure gradient of production wells. Experiments show that it can be applied to parameter calculation of all reservoir types and all reservoir pressure distributions in a water flooding oilfield. For example,it has been used to calculate the rational pressure system of injection-production of the No. 1- 3 sandstone reservoirs in the 2ndMember of Shahejie Formation of Shengyi block,Shengtuo oilfield. And the result shows that the ratiional ratio of oil to water wells is 1. 42,the rational formation pressure-keeping level is 17. 29 MPa while the rational fluid-production volume and water-injection are 14 572. 41 m^3/ dand 15 906. 88 m^3/ d respectively,with 12 452. 41 m^3/ d and 13566. 88 m^3/ d more than before,and with a remarkable increase of fluid production and water injection.