Well Testing Model With Recharge Boundary In Tight Gas Reservoir And Application Research

Tight gas reservoir with low porosity and low permeability and serious stress sensibility is unconventional gas reservoir.Well testing curve of some gas wells in Sulige gas field,the tail of which appear downward trend,can’t be reasonably explained by conventional and modern method.In this paper,the extensive research was investigated based on tight gas reservoir,fractured well model and recharge boundary.A representation model of recharge boundary suited to tight gas reservoir is established and parameters are figured out,and source functions of recharge boundary was established.Well test model of fractured well based on recharge boundary and stress-sensitive effect in tight gas reservoir was established,the flow conductivity of whose fracture is infinite and finite.Strong nonlinear is solved on use of perturbation transformation method.The advantage of superposition theorem introduces wellbore storage coefficient and skin factor in Laplace space.Curves of well test model based on recharge boundary in tight gas reservoir are drew,their characters are analyzed,and flow stages are divided.Wellbore storage and skin effect covers up early-stage.Stress-sensitive effect leads to curves rising in middle and later stages.Characters of recharge boundary are heave curve,and its strength impacts on the peak and its appropriate time,and its pressure impacts on the peak only.Based on feature points method,it’s proposed to interpreting methods of well test in tight gas reservoir with recharge boundary.Calculation formula of feature points in flow stages is given,and we can determine parameters of recharge boundary.In the sample application,the model with recharge boundary fitted abnormal well testing curve,and explained boundary characteristic,and applicability of fractured well test model based on recharge boundary in tight gas reservoir was proved.