Downhole Tractor Turbine Powering Wheels for Casing Obstructions
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Solution Overview
Problem
The difficulty in lowering a casing string to its intended depth in a wellbore due to debris or obstructions within the wellbore, which can lead to inefficient operations, increased costs, and safety concerns.
Innovation Solution
A downhole tractor assembly with a tubular main body, fluid flow passage, turbine, alternator, and electric motors that drive wheels to overcome obstructions by rotating the turbine with fluid flow and applying additional force to the casing string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a casing string is lowered into a wellbore, then hydrocarbon production capability is established, but debris or obstructions within the wellbore can interrupt or prevent the casing from reaching its intended depth
Solution Approach 1:
A tractor assembly is introduced as an intermediary device between the casing string and the wellbore obstruction. The tractor assembly includes powered wheels that contact the wellbore wall to provide propulsive force, and a fluid flow passage with turbine that converts hydraulic energy from drilling fluid into rotational motion to drive the wheels, enabling the casing to overcome obstructions
Solution Approach 2:
The tractor assembly utilizes hydraulic power transmitted through drilling fluid circulating through the wellbore. A fluid flow passage within the tractor assembly directs the hydraulic flow to rotate a turbine, which in turn drives the powered wheels through a transmission system, converting hydraulic energy into mechanical propulsion to move the casing string through obstructions
2Device complexity
If conventional casing lowering methods are used, then installation simplicity is maintained, but operational costs increase and safety concerns arise when obstructions are encountered
Solution Approach 1:
The tractor assembly serves multiple functions: it acts as a propulsion system with powered wheels to overcome obstructions, a hydraulic power conversion device with turbine and transmission system, and an integrated component that can be attached to and moved with the casing string. This multi-functionality allows a single device to handle both normal casing lowering and obstruction overcoming
Solution Approach 2:
The tractor assembly incorporates a transmission system with variable gear ratios that can dynamically adjust the rotational speed and torque delivered to the wheels based on the resistance encountered. The system can operate in different modes: free-rolling during normal lowering and powered propulsion when obstructions are encountered, with the ability to vary wheel speed and torque continuously
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the casing string to reach its intended depth efficiently, reducing operational costs and enhancing safety and effectiveness of wellbore operations by providing additional force to dislodge obstructions.
Implementation Method 1
a turbine disposed in the flow passage and configured to be rotated by a flow of fluid from the tubular string through the fluid flow passage
Implementation Method 2
an alternator disposed in the main body and configured to convert the rotation of the turbine into electricity
Implementation Method 3
one or more electric motors configured to, when actuated by electricity from the alternator, drive rotation of the one or more wheels
Data Source
AI summary
A downhole tractor assembly includes tubular main body configured such that a central axis of the main body is parallel with an axis of a tubing string when the tool is disposed in the tubing string. The tractor assembly includes a fluid flow passage within the main body, a turbine disposed in the flow passage, an alternator disposed in the main body and configured to convert the rotation of the turbine into electricity, one or more wheels extending radially at least partially from an exterior surface of the main body, and one or more electric motors configured to, when actuated by electricity from the alternator, drive rotation of the one or more wheels. The tractor assembly is configured to attach to a tubular string disposed in a wellbore, such that fluid flowed through the tubular string flows through the fluid passage and rotates the turbine.