裂缝性碳酸盐岩底水油藏临界产量计算研究

Critical production calculation of fractured carbonate bottom water reservoir

为了有效合理地开发裂缝性底水油藏,针对裂缝性底水油藏中裂缝发育不均、非均质性强的特点,将其储层抽象为水平渗透率渐变的地质模型,基于油气稳定渗流理论推导了考虑平面径向流和球面向心流的临界产量计算公式,并通过实例分析了油层厚度、打开程度、渐变系数和垂向渗透率系数对临界产量的影响。结果表明,平面径向流临界产量公式适合于油层厚度小的裂缝性油藏,而球面向心流临界产量公式更适合于油层厚度大、打开程度较小的裂缝性油藏,其临界产量随着油层厚度、垂向渗透率系数和渐变系数的增大而增大,随着打开程度的增大先增加后减小,存在一个最佳打开程度。该研究结果为裂缝性碳酸盐岩底水油藏的合理开发及控制油井产量提供了参考。

In order to effectively and reasonably develop fractured bottom water reservoir, and aiming at uneven fracture develop- ment and strong heterogeneity, the reservoir was abstracted to geologic model with horizontal permeability gradient. Based on filtra- tion theory of oil and gas stability, critical production calculation formula by the consideration of radial fluid flow and spherical cen- tripetal flow was deduced, in addition, through examples, the impacts of some factors on critical production were analyzed, includ- ing reservoir thickness, perforated degree, gradient coefficient and vertical permeability coefficient. The results show that, critical production formula of radial fluid flow is suited for thin fractured reservoir, however, critical production calculation formula of spherical centripetal flow is more suitable for thick and low perforated degree of fractured reservoir, which critical production increases with the increase of reservoir thickness, vertical permeability coefficient and gradual coefficient, on the other hand, the critical production increases first and then decreases with the increase of perforated degree, and there is an optimum perforated degree. The research provides references for reasonably development of fractured carbonate bottom water reservoir and production controlling.