文档介绍：高压气井射孔段套管强度安全性分析
摘要: 在油气田开发中,造成油气井生产套管(以下简称套管)损坏的原因很多,其中射孔作业是主要原因之一。射孔会导致套管发生严重变形或破裂,使套管的强度受到较大影响。本文着重于射孔后套管孔边应力分析。主要内容包括以下几个方面:
(1)对套管的四个挤毁压力公式以及抗内压公式进行了推导。考虑了t/D在五个公式中的重要作用。正确应用挤毁压力、抗内压公式分析套管的受力,减少套管的损坏。
(2)利用复变函数以及弹性力学保角映射方法并根据几何的不连续性,用数值解法计算应力集中系数或给出数值拟合公式,用简化算法将所射孔作为U形凹口,得到了射孔后孔边的应力集中系数计算公式。
(3)用权函数法对套管表面半椭圆裂纹的应力强度因子进行了推导。考虑实际射孔操作以及射孔方式的因素,分析套管在不同射孔条件下的应力强度因子,通过建表分析可得,壁厚、孔径越大,应力强度因子越大。
(4)根据实际情况进行了无损套管的受力分析,得到了套管分别在受内、外压时的极限载荷;根据射孔开裂模型对剩余强度系数进行了分析计算,给出算法。
(5)考虑孔边应力集中和孔边裂纹的影响,考虑高压气井实际工况,根据厚壁筒理论公式及第四章、第五章所得的公式,求得孔边的最大应力,并用第四强度理论校验射孔套管的强度安全性。
关键词:高压气井;射孔套管;应力集中;安全性分析
Intensity And Security Analysis of Perforated Casing in High Pressure Gas Well
Abstract: In the oil and gas field development, resulting in production of oil and gas well casing (hereinafter referred to as casing) damage to many reasons, one of which is the main reason perforating. Perforation can cause serious deformation or rupture of the casing, so that significantly affected the strength of the casing. This article focuses on the stress after perforation of the casing hole.
(1) Derivation of the four casing collapse pressure formula and the internal pressure formula was derived. Noted t / D formula in five plays a very important role. Correct application of collapsing pressure, internal pressure formula, helps us to force a reasonable analysis of the casing to reduce the damage to the casing.
(2) Use plex functions and conformal mapping of elasticity and in accordance with geometric discontinuity,calculated with the numerical solution of the stress concentration factor, or a numerical fitting formula, with a simplified algorithm of the perforation as a U-shaped notch, has been shot Hole after hole stress concentration factor formula.
(3) Casing with the weight function method for semi-elliptical surface crack stress intensity factor is deduced. Consider the actual operation and perforation mode factor analysis of perforating the casing in different conditions, the stress intensity fac