低渗透储层不能产生高速非Darcy流吗?——回应窦宏恩先生

Can not high rate non-Darcy flow take place in low permeability reservoirs?——Reply to Mr Dou Hongen

低渗透储层能否产生高速非Darcy流,答案是肯定的,只要地层的Reynolds数足够高即可。关于是低渗透储层容易产生高速非Darcy流,还是高渗透储层容易产生高速非Darcy流,答案肯定是后者。相对于高渗透储层来说,低渗透储层的孔隙小,对流体的束缚能力强,不容易产生高速非Darcy流。但实验结果显示低渗透储层的非Darcy渗流系数高于高渗透储层,即低渗透储层比高渗透储层更容易产生高速非Darcy流,这显然是一个实验假象。矿场上极少使用实验测量结果,而是直接应用矿场测试资料研究气体的渗流问题。气井的产能方程包括了高速非Darcy渗流项,低渗透储层和高渗透储层的产能公式在形式上完全一样,只是方程的系数不同而已。

Whether high rate non-Darcy flowcan take place in lowpermeability reservoirs,the answer is yes if the Reynolds number is high enough.Whether high rate non-Darcy flowis easier to take place in lowpermeability reservoirs or in high permeability reservoirs,the answer is that it is easier to take place in high permeability reservoirs because the smaller pores in lowpermeability reservoirs tend to confine fluids flow.However measurements in lab show the non-Darcy coefficients of lowpermeability cores are higher than those of high permeability cores,which implies that high rate non-Darcy flowis easier to take place in lowpermeability reservoirs than in high permeability reservoirs.This is a false appearance in experiment.The measurements in lab are seldom applied to field analysis,while well test data are the best choice for engineers to research the gas flow in reservoirs.All the deliverability equations of gas wells contain a term of high rate non-Darcy flowregardless of high permeability reservoirs or lowpermeability reservoirs.All the equations have the same form,but the equations coefficients take different values.