Research And Application Of The Mathematical Model Of Proppant Backflow Of Deep Dense Gas Fracturing Horizontal Wells

The reservoir of Shahezi Formation in Xushen Gas Field is a low porosity and low permeability reservoir.The heterogeneity is strong and the lithology is complicated,but the yield is high.With using horizontal well barehole fracturing,the yield of the reservoir is high,but the proppant backflow problem is very serious.Now the workers mainly use their experiences to solve this problem,but they are lack of the theoretical basis.In this paper,we make four different evaluation experiment with using the proppant that the Daqing research institute provides,to find the law of proppant backflow.At the same time,this paper builds two mathmatical models of the proppant backflow combined with the reservoir characteristics of Shahezi Formation.One is based on the process of fracturing fluid,the other is based on the process of gas production.This paper analyzes the model of the proppant particles in different states.Based on the experimental results,we can find the critical condition of the proppant backflow.According to the established model,we use Matlab to write the program for simplifying the calculation steps.This program can not only determine whether the well has the proppant backflow problem,but also get the critical gas flow rate and the critical gas production.Contrasting with the data of this field,the applicability of this program is verified.The research of this paper has some guiding significance for on-site construction.