考虑储层伤害影响的水平气井产能

PRODUCTIVITY OF HORIZONTAL GAS WELLS CONSIDERING RESERVOIR DAMAGE EFFECTS

随着"西气东输"工程的启动,越来越多的水平井在气藏开发中得以应用,但是由于气藏的低渗透性使得钻井过程中产生的储层伤害比常规油藏严重得多。基于坐标变换方法,将储层各向异性空间转换为各向同性空间,利用坐标变换后水平井储层伤害区域同垂直压裂井近井地带渗流特征的相似性,推导出了新的表皮因子计算模型,并将其应用于水平气井产能公式。计算结果分析表明:储层伤害区域渗透率的损失程度对水平气井产能的影响远比储层伤害深度要严重。该方法充分考虑各向异性影响,计算简便快捷,能够广泛应用于气藏水平井开发的早期评估以及水平气井的产能预测。

With the start of 'West to East Gas Transmission' project,more and more horizontal wells are applied in the development of gas reservoirs.However,due to the low permeability of gas reservoirs,the reservoir damage caused in drilling process is much more serious than that of conventional reservoirs.Based on the coordinate transformation method,the anisotropic space of reservoir can be converted into isotropic space.Then after the coordinate transformation,by using similarities of percolation characteristics between reservoir damage regions of horizontal wells and near bore zones of vertical fracturing wells,a new calculation model for skin factor is derived,which is employed in the productivity formula for horizontal gas wells.The result of the analysis and computation showed that the impact on horizontal gas wells caused by the degree of permeability loss in reservoir damage region is far more serious than that of reservoir damage depth.This method,fully considering the influence of anisotropy and with advantages of easy and efficient calculation,can be widely used in early evaluation for the development of horizontal wells in gas reservoir and productivity predication of horizontal gas wells.