Study On Shale Reservoir Flowback Ratio And Productivity Forecast Of Longmaxi Formation In Sichuan Based On Neural Network Analysis

In shale gas production,post-fracturing flowback management is an important part of shale gas production.Appropriate flowback measures can not only maintain the conductivity of the shale gas flow channel,but also minimize the fracturing fluid's impact on storage.The damage to the layers in turn facilitates later production.However,the flowback ratio is an important feature of flowback,and the existing research has failed to clearly define the main control factors affecting the flowback ratio and the laws of flowback ratio and capacity.Traditional analytical methods or numerical simulation methods cannot effectively predict the flowback ratio and production capacity,and cannot control the production rate by controlling the flowback ratio,which is difficult to increase the output of a single well.This study first carried out a simulation experiment of flowback,analyzes the influence of factors such as well time,wellhead pressure,porosity,clay content,Poisson's ratio on the flowback ratio,provides data support for the neural network algorithm,and provides suggestions for on-site stimulation and reconstruction.Furthermore,a machine learning algorithm is used to predict the rate and productivity of shale gas wells in some blocks of the Longmaxi Formation in the Sichuan Basin.First,based on the geological data,engineering data and production data of 250 wells,a BP neural network model is constructed to predict the flowback ratio and production capacity,and the main control factors of the flowback ratio and production capacity are determined by the weight of the influencing factors during the prediction.Then generate geological index,engineering index and comprehensive index based on the main control factors,use the method of multiple nonlinear fitting to determine the relationship between the flowback ratio and production capacity,make a flowback ratio and production capacity prediction board,and compile the prediction based on python language software.The study found that the shale gas well flowback ratio and production capacity prediction plate and software applicable to the Longmaxi Formation in the Sichuan Basin can realize real-time prediction with accuracy to meet site requirements.The results of flowback simulation experiments show that the wellhead pressure and porosity are positively related to the flowback ratio,the clay content is negatively related to the flowback ratio,and the Poisson's ratio is not significantly different from the flowback ratio.And in the actual production process on site,the manhole time should not exceed 14 d.The actual situation on the site shows that when the flowback ratio of the Longmaxi Formation shale block in the Sichuan Basin is in the optimal range of 20%-40%,it has greater gas production,which means that it can optimize the control of drilling design and fracturing design.The flowback ratio is in the optimal range,which can maximize gas well productivity.