一种确定低渗透油藏启动压力梯度的新方法

原油中的表面活性组分在多孔介质的孔道壁面上吸附形成了边界层，从而使得低渗透油藏的启动压力梯度远大于中高渗油藏的启动压力梯度。首先分析了边界层的形成及影响因素，然后建立一个孔隙网络模型来进行渗流模拟。通过在孔道中引入边界层，可以利用孔隙级网络模型作出压力梯度与渗流速度之间的关系曲线，即渗流曲线。由渗流曲线便可进一步确定启动压力梯度。该方法首次在确定启动压力梯度时直接考虑了边界层的影响，而且将孔隙级网络模型的应用进一步扩展到了低渗透油藏。

A New Method for Determination of Start-Up Pressure Gradient in Low Permeability Reservoir

The adsorption of crude oil surfactant component in the wall of pores and throats forms a boundary layer which has more influence on low permeability reservoirs than that on high permeability reservoirs. It is this boundary layer that causes start-up pressure gradient in low permeability reservoirs to be much higher than that in middle-high permeability reservoirs. In this paper, the formation of boundary layer and its influence factors are analyzed, and then a pore scale network model is developed for percolation simulation, finding out a flow curve between pressure gradient and flow velocity, by which determining the start-up pressure gradient. This method studies the start-up pressure gradient by considering the effect of boundary layer directly for the first time. In addition, it extends the usage of pore scale network model to low permeability reservoirs.