Research On Production Decline Analysis Methods And The Application In Tight Gas Field

Due to low formation permeability,stretched transition period between different flow regimes in the process of production,and some specific gas flow characteristics in porous media such as threshold pressure gradient,stress sensitivity and slippage effect,the production decline in tight gas field is more complicated than that in conventional gas field.Therefore,it is very imperative to do further research on production decline analysis with the consideration of characteristics above.Firstly,this paper fully considered different types of wells,different types of formation parameters,different flow regimes to which the production data belong,as well as porous flow mechanisms in tight gas field,and developed single well and block production calculation models.Then,the performances of diverse decline forecasting models for single well and block were evaluated by using generated production data from the calculation models.Conclusions were drawn that: As for single wells,if the production data exceed boundary dominated flow,fractured vertical well suits harmonic model and fractured horizontal well suits modified Kopatov model.If the production data don't exceed boundary dominated flow,hybrid model is suitable;As for blocks,stable type suits generalized model,peak,bounce and section tyepe suits harmonic model.A workflow to determine suitable decline models was obtained and applied to Sulige gas field.Decline parameters were obtained.By analyzing decline rates and the ratio of decline rates,it was concluded that single well decline was influenced by permeability and starting time of boundary dominated flow,and block decline was influenced by production stage,well controlled reserve and permeability.