Case Histories of a New Wireline Logging Tool for Determination of Free Point in Support of Drilling and Pipe Recovery Operations

Abstract

A new logging tool that is will identify the free point in drill collars, drill pipe, tubing, or casing has been developed and field tested. The tool is commercially available in the wireline service sector for drilling support and well abandonment operations. Unlike previous free point methods, which used strain measurements of the pipe obtained as a series of stations with and without the application of pipe stretch or torque at each station, this new method is simply overlay of two logging passes. The first logging pass is recorded with the pipe in a neutral weight condition, and the second logging pass is recorded with tension or torque applied to the pipe. The tool utilizes the property of steel called magnetostrictive effect. When a mechanical stress is applied to the steel, the magnetization of the material is modified. Thus when torque or tension is applied to the pipe that is free to move, their magnetization will change. If the pipe is not free to move their magnetization will remain the same. The tool has been successfully tested in steel alloys that have minimal magnetic properties. This new logging tool has many advantages over legacy free pipe determination methods. First, from a rig safety standpoint, the application of pipe stretch, or torque is applied only once for a few minutes for the logging pass. With legacy free point methods numerous stationary measurements were required, with the pipe being stretched/torqued at each station. Since determination of free point is a comparison of two logging passes, real time operations and 24/7 satellite communications allow remote based operator and service company pipe recovery experts to be involved with the well site decisions. While this new technology uses a comparison of two logging passes, well site operations is not dependent on a pipe recovery expert with extensive hands on experience to be on location, or delays waiting for pipe recovery experts to arrive on location. This benefit is extremely important with the aging of the industries workforce. The small diameter logging tool is run centralized, and does not require weight bars added to the tool for slip engagement, this shortens the length of the tool string and simplifies e-line rig up procedures. Introduction Previous generation free point tools utilized strain gauge measurements which detected the stretch or rotation of the drill sting when the free point tool was mechanically anchored in the drill sting and force applied to the pipe. The determination of the free point required many stationary measurements over the estimated stuck point region with the drill string in a neutral condition and then again with either tension, or torque being applied during each recording. Mechanical slip engagement of the strain gauge sensor in the vertical and azimuthal planes is critical. This method often requires many hours of rig time and the talents of a highly skilled free point logging expert. The tool utilizes the property of steel called magnetostrictive effect1. When a mechanical stress is applied on steel material; the magnetization of the material is modified. When torque or tension is applied to the pipe that is free to move, their magnetization will change. If the pipe is not free to move their magnetization will remain the same.

A New Approach for Estimating Free Point in Fishing of Stuck Pipe using Artificial Neural Network

“…A plot of depth versus the percentage of surface torque and pull transmitted down hole shows the deepest point at which the string is free. Performed research in the case of free point estimation are in field of logging tools and modifying or utilizing new tools and techniques [8,9]. This study focuses on a novel topic of free point estimation, by using drilling parameters.…”

Middle East Case-Study Review of a New Free-Pipe Log for Stuck-Pipe Determination and Pipe-Recovery Techniques

“…It was not until the late 1990s that magnetic methods measuring the magnetic properties of the pipe were introduced (Trevillion 1988, Estes 2007, and Smaardyk 2010; however, limitations in technology did not allow for full deployment until the recent introduction of a tool, based on new sensors and electronic technology development, that could continuously record the magnetostrictive properties of the pipe under different tension conditions (Kessler et al 2009a, Kessler et al 2009b The new tool provides a continuous log of the magnetostrictive properties and typically reads log values between 9 and 15 units, while the response is close to zero when the magnetic effect is fully removed when working the pipe once the logging tool is at the bottom. Another technique that has not been fully developed is to apply different tension to the pipe while observing the change in response, which will be the same when the pipe is 100% stuck and there is no pipe stretch or change in property.…”