大位移井井壁稳定机理及安全密度窗口分析

Study of Wall Stability of Extended Reach Well and Analysis of Security Density Window

从井壁稳定的岩石力学机理出发,分析大位移井周的应力分布规律,建立大位移井井壁稳定的力学模型。根据库仑-摩尔强度准则和最大拉应力破裂准则,计算大位移井的井壁坍塌压力与泥浆安全密度窗口。利用Visual Basic语言编制了大位移井井壁稳定分析计算软件,分析影响大位移井井壁稳定性的因素,并计算大位移井的井壁坍塌压力与泥浆安全密度窗口。采用某油田的实际资料,计算出在不同井斜角和井斜方位角下的坍塌压力与泥浆安全密度窗口。计算结果表明,大位移井井壁坍塌压力、安全密度窗口与原地应力状态、井斜角和井斜方位角有直接关系,并提出了最优的井眼轨迹设计方案。

Based on stable rock mechanism of well wall, the stress distribution around the well wall was analyzed, the mechanical model of extended reach well stability was established. The well collapse pressure of extended reach well and the security density window of drilling fluid was estimated based on the Coulomh-Moore strength criteria and the maximum tension stress fracture criteria. The mechanics stability analysis of extended reach well was compiled by using the Visual Basic. The factors of extended reach well wall stability was analyzed with this software, and the hole collapse pressure and the security density window of drilling of extended reach well was quantitative estimates. The calculation of collapse pressure and security densitywindow of drilling fluid based on the condition of different inclination and drift azimuth for the field data of one oil field showed that there was direct relationship between the hole collapse pressure of extended reach well, the security density window of drilling fluid and the status of the stratigraphic in-situ stress inclination, drift azimuth. Finally, the optimal design of hole trajectory was presented.