Guo Xiao, Zhao Xianyang, Yang Hongbo. A new method for evaluating the productivity of abnormally high-pressure and low permeability gas reservoirs[J]. Petroleum Reservoir Evaluation and Development, 2018, 8(6): 13-18.DOI:
we cannot use the conventional gas reservoir productivity evaluation equation to accurately predict the abnormal high pressure and low permeability gas reservoir capacity. Based on this fact
we considered the actual seepage of abnormal high pressure and low permeability gas reservoirs and established a new physical model to regionalize the seepage zone of gas reservoir. By the novel pseudo pressure function and the principle of superposition
and on the basis of considering the critical radius of gas flow
high-speed non-Darcy flow of gas
pulse effect
reservoir permeability stress sensitivity and starting pressure gradient effect
a new abnormally high pressure and low permeability gas reservoir productivity equation was deduced
and the validity of equation by actual test date was tested. The results showed that the relative error between the calculation results of the conventional productivity equation and the actual capacity test results without considering the influence of seepage area and multi factors could be as high as 21.5 %. The relative error between the capacity calculation results of the new equation and the actual capacity test was less than 5 %
and with the decrease of the bottom hole flow pressure
the high velocity non-Darcy flow effect
the starting pressure gradient effect and the permeability stress sensitivity effect could lead to the serious decrease of the gas well production. However
the critical radius of gas low velocity and the effects of pulse on gas well productivity were small.