天然裂缝对油藏开采特征的影响

在低渗透油田开发过程中，天然裂缝直接影响了地下多孔介质中流体的流动和低渗透油田的开发效果。文章利用数值模拟的方法，计算了低渗透油田面积注水条件下存在天然裂缝时的开发效果，分析天然裂缝裂缝密度、方位、长度、导流能力对油藏开采特征的影响。研究结果表明：随着裂缝密度增加，采出程度越高；与主流线方向平行的裂缝，容易造成注入水突进，见水时间早，无水采收率低；裂缝长度越长，增加了低渗透油田的渗透性，有利于提高采油速度；在相同裂缝方位的情况下，采出程度随裂缝渗透率的增加而减小，减小程度随裂缝的增加而增加，平行于主流线方向裂缝采出程度的减小幅度大于垂直于主流线的裂缝。在低渗透油田开发设 计时，应合理的判断、考虑和利用天然裂缝以提高原油采收率。

EFFECT OF NATURAL FRACTURE ON THE LOW PERMEABILITY RESERVOIR PRODUCTION CHARACTERISTICS

In the development of low permeability reservoirs, natural fractures have great effects on the flowing of fluids and the oil recovery. Using the numerical simulation method calculated the development effect of natural fractures, analyzed the effects of fracture density, fracture orientation, fracture length and fracture flow conductivity on production characteristic. The results show that with the fracture density increasing, the oil recovery increases, especially the fracture paralleling with the main streamline has a great effect on the oil recovery. When the facture length is longer, the injected water runs faster easily, so the oil recovery reduces; under the same facture orientation situation, the oil recovery will reduces with the facture permeability increasing, besides, the oil recovery is affected by other factors. The recovery ratio of the fracture paralleling with the main streamline is more than that of the perpendicular fracture.