致密低渗油藏压裂水平井合理生产压差优化设计

Optimization of reasonable production pressure difference of fractured horizontal well in low permeability tight reservoirs

为了建立有效的数值模拟方法来计算储层压裂投产水平井合理生产压差,以HH油田延长组为例,对致密储层存在明显的启动压力梯度和裂缝存在压敏效应等问题进行了研究,并将动态渗透率与压敏效应共同引入数值模拟计算中,对渗透率进行了修正。动态渗透率理论能较好地模拟低渗储层非线性渗流特征,因此建立了低渗油藏压裂水平井产能数值模拟新方法,该方法综合考虑了低渗油藏启动压力梯度和压敏效应对水平井产能的影响。结果表明,新的数值模拟计算方法更符合低渗油藏压裂投产水平井的生产特征,启动压力梯度与压敏效应对水平井产能影响明显,并优化出HH油田压裂水平井合理生产压差范围。

In order to establish effective numerical simulation method to calculate the reasonable production pres- sure difference of fractured horizontal well, the threshold pressure gradient and pressure-sensitive effect in tight and fractured reservoirs of Yanchang Formation in HH oilfield, Ordos Basin. The permeability was modified by introducing dynamic permeability theory and pressure-sensitive effect into jnumerical simulation calculation, since the theory could effectively simulate the characteristics of nonlinear flow in low permeability reservoirs. Therefore, a new method for productivity of fractured horizontal well in low permeability reservoir was estab- lished, which takes into consideration the effects of threshold pressure gradient together with pressure-sensitive effect on the productivity of fractured horizontal well. The results indicate that the calculation result by this new numerical simulation method accord well with field production characteristics of fractured horizontal well in low permeability reservoirs, and there are apparent effects of threshold pressure gradient and pressure-sensitive effect on productivity of fractured horizontal well. In addition, the range of reasonable production pressure difference of fractured horizontal well in HH oilfield was optimized.