Study of Airtight Makeup and Breakout Technology for Gas Well Snubbing

Abstract

In the process of oil/water well snubbing, we usually use the method which tubing joints can be pre-released above the wellhead and removed in the wellbore to trip the tubing strings or tools in the case of no tubing plug. But tubing seals in gas well are face seals, tubing joints cannot be pre-released because of gas leakage. This problem restricts the development and application of domestic snubbing units for gas well. To solve this problem, the airtight makeup and breakout device is developed, it is equipped between the working BOP stacks and security BOP stacks of snubbing units, cooperate with the rotating slips, tubing joints can be screwed on and off when it meets special snubbing work conditions, such as no tubing plug or tubing leakage. The device is composed of main clamp system, back clamp system and hydraulic transmission system; the power is transmitted by a hydraulic motor to the two drive gears which make the main clamp rotated. In order to verify the reliability of the device, we establish the dynamic model of the clamping mechanism, and the driving torque curve, the radial pressure curve and the rotation curve are analysed, the results shows that the double-layer main clamp system has advantages of little embedding depth, high safety and uniform of radial pressure, all are up to the standard. Based on the research, we manufacture the airtight makeup and breakout device, and two laboratory experiments including the gas seal test and hydrostatic pressure test are carried out; the results demonstrate that the gas sealing pressure of the device should be upped to 22 MPa, and hydrostatic pressure strength should be upped to 43 MPa; it meets the production requirements of Jilin and Changqing oil fields. The airtight makeup and breakout technology can effectively improve the safety reliability and applicability of domestic snubbing equipment for gas well; the application prospect is extremely broad.

Copyright 2017, Shaanxi Petroleum Society.

This paper was prepared for presentation at the 2017 International Petroleum and Petrochemical Technology Conference in Beijing, China, 20–22 September 2017.

This paper was selected for presentation by the IFEDC&IPPTC Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the IFEDC&IPPTC Committee and are subject to correction by the author(s). The material does not necessarily reflect any position of the IFEDC&IPPTC Committee, its members. Papers presented at the Conference are subject to publication review by Professional Committee of Petroleum Engineering of Shaanxi Petroleum Society. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of Shaanxi Petroleum Society is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of IFEDC&IPPTC. Contact email: paper@ifedc.org or paper@ipptc.org.