西南石油大学学报(自然科学版)

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A New Method for Determining Gas Threshold Pressure Gradients in
Low-permeability Rock

Many experiment results show that there exists a threshold pressure gradient when gas is percolating in low permeability
reservoir. As it is difficult to directly determine the threshold pressure gradient,the low-pressure and low-velocity
percolation experiment is the usual method used to obtain the threshold pressure gradient. However,the effect of gas slippage
under low pressure does not work under the formation condition. Thus there exist differences between the threshold pressure
gradient value obtained by Wufan’s method and the actual results. In order to get a more accurate value of threshold pressure
gradient,a new method which eliminates the slippage effect is presented this paper and provides a more accurate threshold
pressure gradient for developing low-permeability gas fields.   

  1. 1. Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu,Sichuan 610059,China
    2. Exploration and Development Research Institution of Zhongyuan Oilfield Company,Puyang,Henan 457001,China
    3. School of Petroleum Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China
  • Online:2013-06-01 Published:2013-06-01

Abstract:

Many experiment results show that there exists a threshold pressure gradient when gas is percolating in low permeability
reservoir. As it is difficult to directly determine the threshold pressure gradient,the low-pressure and low-velocity
percolation experiment is the usual method used to obtain the threshold pressure gradient. However,the effect of gas slippage
under low pressure does not work under the formation condition. Thus there exist differences between the threshold pressure
gradient value obtained by Wufan’s method and the actual results. In order to get a more accurate value of threshold pressure
gradient,a new method which eliminates the slippage effect is presented this paper and provides a more accurate threshold
pressure gradient for developing low-permeability gas fields.

Key words: low-permeability, gas reservoir, percolation, threshold pressure gradient, gas slippage effect