Abstract

A wireline tractor has been developed with an integrated individual arm-closing mechanism that enables losing traction in only one arm while all the others are delivering the traction necessary to overcome the increased force in navigating an obstacle.

Wireline tractors convey logging tools, perforating guns, and mechanical services in highly deviated and horizontal wells. In many cases, they are an efficient alternative to coiled tubing because of their small footprint, quick deployment, minimal flow disruption, and fast tractoring speed. However, tractors cannot easily negotiate obstacles such as restrictions, completion equipment, pipe damage, and debris accumulation.

This problem is tied to the traction principle. When the tractor encounters an obstacle, higher push force is required, which means higher pressure is needed on the arms to increase the grip. At the same time, one arm must close to navigate the obstacle, which requires lower arm pressure. The solution has been to operate two entire tractors in tandem and close one tractor at a time through the restriction. This method necessitates to run an excessive number of assets and increases the toolstring length.

To solve this problem, a wireline tractor has been developed that uses an individual arm-closing mechanism. This unique feature enables losing the traction of only one arm while the other arms are delivering the traction to overcome the increased force.

This mechanism is built in the tool and is available at any time without any specific tool preparation, planning, or module addition, which eliminates undesirable trips in and out of the wells to reconfigure the toolstring in case of an unexpected obstacle.

This innovation has been successfully qualified in many tractor operations. Two cases in the Gulf of Mexico offshore and in North America land will be presented in which this feature was instrumental to reduce the toolstring length and asset overdeployment in overcoming expected and unexpected completion restrictions.

In the first operation, this solution enabled to navigate several side pocket mandrels, which are well-known challenges for tractors due to their complex geometries. In the second case, it saved a deemed inevitable trip to reconfigure the tractor on surface when the tractor encountered an unexpected completion restriction.

The breakthrough design of the arm-closing mechanism significantly increases overall tractor ability to successfully reach the job objective while reducing nonproductive time, resulting in more efficient operations and reduced costs.

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