J55、N80 油管在CO2 干法压裂环境中的适应性

Adaptability of J55 and N80 tubings to CO2 dry fracturing

余曦

YU Xi

中联煤层气有限责任公司研究中心

Research Center of China United Coalbed Methane Co. Ltd., Beijing 100016, China

CO2 干法压裂施工过程中，CO2 处于超临界低温状态，对压裂管柱冷却效应明显，因此对压裂管柱的性能要求更高。结合CO2 干法压裂的技术原理和特点，借鉴ASTM 标准开展了2 种不同钢级的油管试样的冷处理力学性能的试验分析。结果表明，在–60 ℃拉伸试验中2 种钢级管材试样均未达到脆韧转变的临界点；在–60 ~ –20 ℃冲击试验中，J55 油管试样有明显变脆趋势，而N80 油管试样未出现此现象。因此，N80 油管满足CO2 干法压裂低温改造技术安全性能要求，可以保障施工的安全进行。

In the process of CO2 dry fracturing, CO2 is at the state of supercritical low temperature, having apparent cooling effect on fracturing strings. In this circumstance, the higher property of fracturing string shall be essential. In reference to ASTM standard, the tubing samples of two different steel grades (J55 and N80) were tested in terms of their mechanical properties after cold treatment according to the technical principles and characteristics of CO2 dry fracturing. It is shown that the samples of both steel grades don’t reach the critical point of brittle-ductile transition in the extension test at –60℃. In the impact test at the temperature from –60℃ to –20℃,brittleness trend is apparent in the sample of J55 tubing, but never occurs in the sample of N80 tubing. It is concluded that the N80 tubing can satisfy the safety requirements for low- temperature CO2 dry fracturing, thereby ensuring the safe operation.

10.13639/j.odpt.2016.04.014