基于突变理论的油气井出砂预测新方法

根据弹塑性力学理论建立了考虑渗流情况下的油气井井眼围岩的势能函数，以该势能函数为基础，应用突变理论的尖点突变模型研究油气井的出砂物理过程，进而建立了出砂预测的全新数学模型，求取无砂生产的临界流速，并在此基础上对影响出砂的敏感性因素进行了分析。首次引入突变理论对油气井出砂机理进行分析，建立了无砂生产临界流速的全新求解方法。实例表明该模型的计算结果可靠，敏感性分析表明塑性区的污染是出砂的主要原因。相对以往出砂预测模型，该模型考虑的因素更多，计算结果更可靠。应用突变理论研究油气井出砂机理为出砂预测提供了新的研究方法。

A NEW PROBE OF SAND PRODUCTION PREDICTION BASED ON CATASTROPHIC THEORY

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.