Research On Influence Factors Of Gas Well Productivity In YC Ultra-low Pressure Stage

The YC field was formally initiated on January 1,1996.It has been developed for 22 years.At present,there are 15 production wells in the entire gas field,and the pressure coefficient in the main YC field is only about 0.12.The stable gas supply capacity is affected and the ultra low pressure is now affected.Analysis and research on the influencing factors of productivity in high temperature gas wells.This paper takes YC ultra-low pressure high temperature gas well as research object,and completes it under the support of CNOOC’s"Influencing factors of ultra-low pressure and high temperature gas well productivity" project to determine the influencing factor mechanism and yield prediction of YC gas field under ultra-low pressure and high temperature conditions.Based on the YC field rock samples and actual site production data,the experimental study on the productivity of ultra-low pressure high temperature gas wells was investigated,including the reservoir stress sensitivity test,water lock damage test and long core back-convergence damage test.Based on the experiments,the analysis was conducted.The gas field considers the loss of production due to stress sensitivity,water lock damage,back coagulation damage,reservoir physical properties,and salting out.It analyzes and evaluates the capacity under the influence of various factors,and finally calculates the factors that accurately determine the factors affecting productivity.In the above,the integrated production capacity equations that consider the effects of various factors are derived to apply the YC ultra low pressure high temperature gas well productivity synthesis equations.In combination with the experimental results and productivity evaluation,a numerical simulation model of ultra-low pressure high temperature gas wells is established to predict the YC gas field productivity.Based on the above research contents and results,the following conclusions are obtained:(1)Comparing irreducible water with unbound water,the stress sensitive effect of the core with irreducible water is stronger;under full pressure,the stress-sensitive effect of the high-permeability core is weak,and the stress sensitivity effect of the middle-low permeability core is significant;the low-pressure stage,high school The stress sensitivity effect of core rock is weak,and the stress sensitivity effect of low permeability core is strong.(2)With the increase of core soaking soaking time and the core water saturation increasing to more than 35%,the permeability of middle and low permeability cores is higher than 50%.The dry core water lock damage is slightly higher than the core with bound water.(3)The permeation rate decreased by 19%when the condensate saturation was longest in the medium-permeability core,and the permeability decreased by 22.51%when the low-permeability long core gas condensate saturation was the maximum.The damage was far lower than the water lock damage.(4)Based on experiments,analyze the productivity loss taking into account the effects of stress sensitivity,water lock damage,reverse condensation damage,reservoir physical properties,and salt precipitation,and establish the scope of impact and the factors affecting productivity of various influencing factors.The comprehensive evaluation method shows that water lock damage has a greater impact on productivity in the low pressure stage;(5)The production capacity equations for production capacity prediction considering various influencing factors have been established,and applied to the actual production process of YC ultra-low pressure high temperature gas wells.On-site production data is 75 to 79%of unpredictable flow,and its practicality is strong.