试油封隔器水力锚剪切强度及咬入套管深度分析

轴向载荷作用下,试油封隔器水力锚与套管咬合发生挤压变形,载荷越大,变形越大,严重时甚至导致水力锚剪切失效。为了解与套管咬合过程中试油封隔器水力锚剪切强度及咬入套管深度,根据水力锚结构特点,由能量守恒定律建立水力锚爪牙剪切应力公式、挤压应力公式和咬入套管深度公式,对比分析了常见规格水力锚爪牙咬入P110和TP140两种不同钢级套管的最大深度。算例分析表明,相同载荷作用下,水力锚爪牙所受挤压应力远大于剪切应力;水力锚爪牙与套管之间最大挤压应力和咬入套管最大深度是管柱内外压差的非线性函数;相同内外压差时,水力锚爪牙咬入P110套管时所产生的最大挤压应力比咬入同规格TP140套管时小的多;但咬入P110套管的深度却是咬入TP140套管的114%。

Shear Strength and Invasion Depth into Casing of Hydraulic Anchor for Packer in Well Testing

Deformation will occur between the hydraulic anchor of packer and casing when axial compression load is applied, and there will even be shear failure if the load is excessively large. To make clear the shear strength and invasion depth of hydraulic anchor for packer in well testing, the formulas of shear stress, compressive stress and invasion depth into casing when the packer cut into casing were deduced based on the law of the conservation of energy. The maximum invasion depths into P110 casing and TP140 casing were compared when the diameters of casing and hydraulic anchor kept the same. It was found that the compressive stress was considerably larger than the shear stress. And, the maximum compressive stress between casing and packer as well as the invasion depth into casing both changed nonlinearly with the inner and outer pressure difference of tubing string. Although the maximum compressive stress in P110 casing was smaller than in TP140 casing, the invasion depth into P110 casing is 114 percent of that into TP140 casing.