Nonexplosive Tubing Cutter for Safe, Efficient Pipe Recovery Operations

Abstract

Abstract Pipe recovery is extremely important in modern well intervention programs. Tubing can become stuck in a wellbore for a variety of reasons, requiring the operator to determine the location of the stuck point and to subsequently conduct a back-off or cutting operation. These operations allow removal of "free" sections of tubing, giving the operator greater access to remaining sections using more robust fishing equipment. Conventional cutting devices have safety, operational, and logistical drawbacks. Chemical cutters use harsh, corrosive chemicals that require trained / certified operators and special storage - handling procedures. Jet cutters use explosives to sever pipe, leaving a flared and sometimes difficult fishing profile. Explosives require licensed operators and storage facilities and can be difficult to transport globally. A new development in pipe recovery methods is the motorized cutting tool (MCT). The MCT provides the industry with a reliable and safe alternative to explosive and chemical cutting devices. It is an efficient single run solution, whether requiring single or multiple cuts. The non-explosive and compact cutter addresses these challenges; providing a tool that improves performance and efficiency while eliminating safety concerns. Globally transported in a moment's notice, the surface monitoring capability provides the only system in the industry capable of verifying the cut during the operation. The unique design of the tool enables making cuts with the tubing in either tension or compression. In this paper, the authors will review the basic design and construction of the MCT. They will go on to describe the various operations performed; ranging from single cuts to multiple cuts in one trip, various tubing sizes, tubing in compression or tension. Following this, they will go on to conclude how this system has demonstrated efficiency improvements while eliminating safety concerns compared to existing pipe recovery methods. Introduction There are several methods available to the industry to sever tubing downhole. The primary cutters in use today rely on explosives, chemicals or thermite reations, with each one presenting its own safety challenges and risks. Each method has its advantages, disadvantages and operational limitations; however, selection of the right method for a given application can still be difficult given the relatively high rate of failure (Jurgens1). The study demonstrates that even when the conventional cutters function properly and specific failure modes are removed from the analysis (well fluids such as heavy paraffin, low order detonation, human error, low pressure tool leaks, improper tool gas ventilation, debris, etc….) that the rate of failure remains high. New Method: An innovative development in pipe recovery methods is the motorized cutting tool. Its main objective is to maximize operating safety and efficiency of pipe recovery operations. In addition, it addresses cutting success improvement with an objective of 100%. The motorized cutting tool is an electro-hydraulic tool that severs downhole tubulars, eliminating the need to use dangerous chemicals or explosives, resulting in a safe, efficient and smooth cut with no flaring or debris left in the well. Figure 1. The tool is composed of two sections. Figure 2. The upper section houses electronics and anchors, which deploy to keep the tool centralized and free from rotation (hold backup) during the cutting operation. The lower section contains a rolling cutter wheel and rotates under the power of an electric motor. As the lower section rotates, hydraulic pressure is applied to the rolling cutter wheel causing it to displace the tubing material.