Abnormal mechanism of deliverability equation in great thickness and commingled producing wells of Puguang gas field and the eliminating method

Puguang gas reservoir is of great thickness,vertically heterogeneity,high productivity and low pressure differential.These factors will cause that the binomial deliverability equation analysis is very sensitive to the bottom hole pressure.So the bottom hole pressure is not measured on the middle depth of the formation,or the slope of binomial deliverability analysis curve will be negative.Considering the effect of heterogeneous and great thickness to the wellbore pressure,the influence of the location of bottom hole pressure gauge on the deliverability equation is analyzed and the reason of abnormal is studied.Then the eliminating method is established considering the effect of formation capacity.It can avoid the negative slope happening effectively.