海洋大位移井井壁力学稳定性研究

The Study of Mechanical Stability of Ocean Extended Reach Well

大位移井的井壁稳定对海洋油气开发过程中的正常钻井十分重要。文章从大位移井井壁稳定的岩石力学机理出发,分析大位移井井壁围岩的应力状态,根据地壳岩石的特性建立了海洋大位移井井壁稳定的各向同性线弹性力学模型,并根据库仑—摩尔强度准则和最大拉应力破裂准则给出了大位移井井壁坍塌、井壁破裂的条件。利用VisualBasic语言编制了Windows环境下的大位移井井壁稳定分析计算软件,利用该软件分析了影响大位移井井壁稳定性的因素,并定量计算大位移井的井壁坍塌压力。对东海某气田的实际资料进行计算处理表明,大位移井井壁坍塌压力与井斜度和井斜方位角有着直接的关系。大位移井井壁坍塌压力随井斜角与井斜方位角的变化规律主要由地层的原地应力状态决定。

The hole stability of extended reach well is very important to the safety drilling of the ocean oil-gas development process. Based on the lithomechanics mechanism of the extended reach well hole stability, the paper analyzed the stress state of the wallrock, established the isotropic linear elasticity mechanical model of ocean extended reach well stability based on the characteristics of crustal rock, and presented the hole collapse and fracture condition of extended reach well based on the Coulomb-Moore strength criteria and the maximum tension stress fracture criteria. The windows software for the mechanics stability analysis of extended reach well was compiled using the Visual Basic. The factors of extended reach well hole stability was analyzed with this software, and the hole collapse pressure of extended reach well was quantitative estimates. The calculation for the field data of one of the gas fields of East China Sea shown that there is direct relationship between the hole collapse pressure of extended reach well and inclination, drift azimuth. And the variation law of the hole collapse pressure of extended reach well along with hole angle and azimuth mostly decided by the status of the stratigraphic in-situ stress.