Oil & Gas Geology ›› 2009, Vol. 30 ›› Issue (1): 122-126.doi: 10.11743/ogg20090118

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A binomial deliverability equation for horizontal gas wells in formations with nonlinear seepage flow features

Yuan Yingzhong1, Zhang Liehui1, Wang Jian1, Pu Yanwei2   

  1. 1. State Key Laboratory of Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. The Second Well Cementing Branch of Bohai Drilling and Exploration Corporation, Tianjin 300280, China
  • Received:2008-10-18 Online:2009-02-25 Published:2012-01-16

Abstract:

A horizontal well is one of the most effective methods for developing low-permeability gas reservoirs which are characterized by the effects of start-up pressure gradient and turbulent flow under high-speed non-Darcy flow.A seepage flow model was established and solved for horizontal gas wells.It involves well-bore structure parameters,turbulent gas flow under high-speed non-Darcy flow in near-wellbore area and start-up pressure gradient.A binomial deliverability equation for horizontal gas wells was derived.Based on strict theoretical derivation and calculation,deliverability of horizontal and vertical wells was compared to understand the influences of start-up pressure gradient and non-Darcy flow on the deliverability of horizontal gas wells.The results indicate that the start-up pressure gradient is in negative linear relationship with the deliverability,the non-Darcy flow decreases the deliverability of horizontal gas wells and its influence on horizontal gas wells is smaller than that on vertical gas wells.

Key words: start-up pressure gradient, binomial deliverability equation, non-Darcy flow, horizontal gas well, formation with nonlinear seepage flow features

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