射孔对水泥环与套管性能影响的分析计算

Analysis of impact of perforation on the performance of cement sheath and casing

在建立水泥环．套管射孔数学模型和有限元分析模型后，计算分析了射孔对水泥环‘套管性能的影响，得出如下结论：（1）射孔是造成套管损坏的主要原因，无水泥环固结，完好套管产生的应力是射孔套管的％；（2）射孔套管壁厚和水泥环固结状态对射孔套管性能影响较大，壁厚12．395mm射孔套管是壁厚7．720mm射孔套管抗挤强度的1．5倍以上，水泥环与套管固结良好且上下固定，可以提高套管抗挤强度；（3）生产中保持内压和外载相近，可以明显减小射孔套管应力；（4）增大水泥环弹性模量，保持水泥环弹性模量在30～35GPa之间，可以提高射孔水泥环．套管抗挤强度。

After the establishment of the perforation mathematical model of cement sheath-casing and the finite-element analysis model, the impact of perforation on the performance of the cement sheath and casing is analyzed by calculation. It can be concluded that: (1) Perforation is the main reason for casing damage, and the stress produced by the intact casing without cementing is the one-third of that of perforated casing; (2) The wall thickness of perforated casing and the cementing condition of the cement sheath have a big impact on the performance of the perforated casing. The collapsing strength of the perforated casing with the wall thickness of 12.395 mm is above 1.5 times that of the casing with wall thickness of 7.720 mm. The good cementing of cement sheath and casing and the upward and downward securing can improve the collapsing strength of the casing; (3) The inner pressure is kept near to the outer load during the production, which can reduce the stress of the perforated casing significantly; (4) The collapsing strength of perforated cement sheath-casing can be improved by increasing the elasticity modulus of cement sheath and remaining the elasticity modulus between 30~35 GPa.