关键词: 出砂, 临界流速, 突变理论, 势能函数, 尖点突变

Abstract:

Taking the effect of fluid flow into account，the authors of this paper present the potential energy function of the surrounding rock system of wellbore on the basis of the elastoplastic theory.Based on the potential energy function，the catastrophic theory is applied here to analyze the mechanism of sand production of oil & gas wells and to establish the predictive model of sand production and the critical flow rate of no sand production is obtained.According to the new predictive model，the effect of some sensitive parameters is analyzed.The catastrophic theory is introduced for the first time to predict sand production and to develop a new predictive model of the critical flow rate without sand production.Case study shows that the predictive result in the model agrees with field data very well.From sensitivity analysis of some parameters，it is indicated that the damage of plastic block results in sand production chiefly.More factors are taken into account to the model and the predictive result is more accurate contrasted with the previous models.The catastrophic theory provides a new solving method for sand production prediction of oil & gas wells.

Key words: sand production, critical flow rate, catastrophic theory, potential energy function, cusp catastrophe