基于出砂特征半径的水平井出砂临界生产压差预测模型

在水平井近井地带地应力分布研究基础上,首次提出破坏特征半径的概念,以特征半径处作为地层破坏出砂的判断位置,分别使用Mohr-Coulomb准则、Drucker-Prager准则、Hoek-Brown准则建立相应的水平井出砂临界生产压差预测模型,并对水平井出砂临界生产压差计算结果进行敏感性分析。结果表明:水平井出砂临界生产压差与井斜角有关,其具体变化规律与原始主应力中垂向主应力与最大水平主应力的关系有关;在同一地区,水平井水平段方位的选取会明显影响其生产中的出砂程度;水平井出砂临界生产压差与特征位置半径的选取有直接关系。

Prediction model for critical sanding pressure drawdown in horizontal wells based on characteristic break radius

Based on the formation stress distribution model around horizontal wellbore,the concept of characteristic break radius was put forward firstly and used as the evaluation location to judge whether the well sanding or not.Three rock failure criterions,which concerns Mohr-Coulomb,Drucker-Prager and Hoek-Brown,were applied to develop the critical downhole pressure condition,and the corresponding critical sanding pressure drawdown prediction models were established.The model was used to analyze the effect of production parameters and rock characteristic on the critical sanding pressure drawdown.The results indicate that the critical sanding pressure drawdown is related to the hole angle,but the varying tendency depends on the relationship of initial formation vertical stress and maximum horizontal stress.In the same reservoir,the well orientation angle affects the sand production degree directly.In addition,the critical sanding pressure drawdown changes with the characteristic break radius obviously.