文章内容

（中石化西南石油工程有限公司井下作业分公司，四川 德阳 618000）

摘要：川西新场须二段气藏埋藏深，储层温度压力高，储层改造时井下管柱温度骤变、内外流体压力变化大，导致井下管柱受载恶劣，管柱失效的风险增高。储层改造所用的井下管柱的受力分析是管柱设计的关键点，而传统的管柱力学模型未细分整个井下作业过程，管柱下入、坐封、改造等各工况的受力边界条件缺少关联，管柱在改造工况下的受力计算并不精准。以单元段储层改造管柱平衡方程为基础，综合考虑温度、压力、井眼轨迹、屈曲等因素，并结合下入、坐封、改造作业过程中温度、压力变化引起的管柱变形及管柱约束条件，建立了井下管柱力学模型。将模型应用于川西新场须二段高压气井储层改造时管柱力学分析，验证管柱力学模型的适用性，为管柱设计提供数据支撑。

关键词：储层改造；高温；高压；井下管柱；力学

中图分类号：TE931         文献标识码：A

Mechanical analysis of downhole string for reservoir stimulation in Xu-2 member of Xinchang area

TANG Zubing

(Downhole Operation Company of Sinopec Southwest Oil Engineering Co., Ltd., Deyang, Sichuan 618000, China)

Abstract: The Xu-2 gas reservoir in Xinchang, west Sichuan, is buried deeply and the reservoir temperature and pressure are high. The fracturing string is badly loaded, which increases the risk of pipe failure because of the sudden change in fracturing string temperature and the significant change in internal and external fluid pressure during the fracturing. The load analysis of the fracturing string used in the reconstruction is the focus of the string design. However, in the traditional mechanical model of tubular string, the whole process of transformation is not subdivided. The load calculation of fracturing string under transformation conditions is inaccurate because the load boundary conditions of various working conditions, such as string tripping, setting and fracturing, are not related in the traditional mechanical model. For this reason, a more accurate mechanical model of the fracturing string is introduced by considering variables such as temperature, pressure, wellbore trajectory and buckling as well as combining them with the deformation and string constraint conditions brought on by changes in temperature and pressure during the tripping, setting and fracturing operations. Finally, the model is applied to the Xu-2 high-pressure gas well in Xinchang, western Sichuan, which verifies the applicability of the string mechanical model and provides data support for string design.

Keywords: reservoir stimulation; high temperature; high pressure; downhole string; mechanics

川西新场地区须家河组二段气藏埋藏深、地层致密、地应力高、储层温度高（>120 ℃）、断层与裂缝发育情况复杂，在钻井过程中钻井液漏失量较大，目的层裂缝系统易受到较严重的污染伤害，导致储层改造破裂压力和裂缝延伸高，改造施工作业时受到温度急剧变化、内外流体压力变化、变径处交变受力、变排量沿程摩阻变化等复杂情况的影响，管柱的安全性、可靠性无法得到保障。因此，急需针对高温高压深井储层改造高施工压力的特点，建立井下管柱力学模型，分析储层改造过程中管柱的力学行为，为管柱设计提供理论依据。

井下管柱的力学问题前人开展了大量的理论研究与实验分析。Johancsik、Ho分别建立了井下管柱的三维软杆模型和刚杆模型 [1–2]。Sheppard通