低渗透地层射孔测试联作的最小测试压差

Minimum Underbalance for Perforating well Testing Operation in Lower Permeability Reservoir

通过将拖曳力函数用于油田测试数据 ,提出了确定低渗透地层最小测试压差的公式和方法。最小测试压差不是依赖于地层流体粘度和压缩性 ,而是为地层孔隙度、渗透率和射孔孔眼半径的函数。在大于最小测试压差下进行射孔测试联合作业 ,有利于堵塞地层的细小微粒返排出来 ,减少地层损害 ,提高负压射孔效果。给出了地层损害比随拖曳力变化的矿场测试数据及其回归直线。将最小测试压差选择方法用于DH2 0井 ,结果表明该方法与实际使用值是接近的。

A formula for calculating the minimum underbalance in lower permeability reservoir is obtained by applying a drag force function to testing data The minimum underbalance is independent of viscosity and compressibility and of reservoir fluids It is a function of the formation porosity, permeability and radius of perforation channels It is helpful to removing the particles of blocking flow channel, reducing formation damage and improving underbalance perforation Perforating well testing operation is performed at a pressure higher than the minimum underbalance The data from fields and the regression curves where the formation damage ratio changes with the drag force are presented in detail An application of the formula in the well DH20 illustrates that the minimum pressure selected is reasonable