Downhole Tool String Gear Housing Fluid Channels
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Solution Overview
Problem
Existing downhole tool strings face challenges in efficiently circulating well fluid through the gear housing to suspend and collect debris, often requiring complex assemblies and limited space for fluid channels, which complicates the transfer of rotational output from the motor to both the pump and operational tools.
Innovation Solution
A downhole tool string design featuring a gear housing with two fluid channels allows well fluid to flow through the tool string, enabling the pump to be arranged above the gear, simplifying the assembly by reducing the rotational output transfer to only the material dislodging means, and incorporating a reservoir for effective debris collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pump is arranged closer to the operational tool to enable fluid circulation in small diameter well tubulars, then the outer diameter of the tool string is reduced, but the gear assembly becomes more complex as it must transfer rotational output to both the pump and operational tool
Solution Approach 1:
The gear assembly is segmented into a first gear connected to the motor for driving the pump, and a second gear connected to the operational tool, with the first gear positioned above the second gear. This segmentation allows independent rotational speed control for each component, simplifying the overall gear assembly architecture while maintaining compact dimensions suitable for small diameter well tubulars.
2Speed
If a gear is arranged to reduce rotational output from the motor to the drill bit, then the drill bit can operate at lower speed, but the pump requires higher rotational speed creating a complex speed transfer requirement
Solution Approach 1:
The rotational speed transmission is segmented into two independent gear trains: a first gear train from the motor to the pump, and a second gear train from the motor to the operational tool. This allows the pump to receive high-speed rotation while the operational tool receives reduced-speed rotation, eliminating the need for a complex multi-speed transfer mechanism.
Solution Approach 2:
The first gear is positioned axially above the second gear, utilizing the vertical dimension to separate the two gear assemblies. This spatial arrangement allows independent optimization of each gear train for its specific speed requirements without interfering with the other, simplifying the overall transmission system.
3Productivity
If the gear housing includes fluid channels for circulating well fluid past the gear, then fluid can be circulated through the tool string, but space for fluid channels is limited in small diameter configurations
Solution Approach 1:
The fluid channels are arranged in the radial and axial dimensions of the gear housing rather than consuming additional axial length. The first fluid channel provides fluid communication between the pump and the operational tool through the hollow tool shaft, while the second fluid channel circulates fluid past the gear in the annular space between the gear outer periphery and the gear housing inner periphery, efficiently utilizing available space.
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
This design enhances the capability to circulate fluid and collect debris within the tool string, reducing the complexity of the gear assembly and improving the efficiency of debris collection and transport to the surface.
Implementation Method 1
The gear reduces the rotational speed from the pump to the material dislodging means
Implementation Method 2
a pump connected to the motor for circulating the well fluid through the downhole tool string and past the material dislodging means
Implementation Method 3
a motor, a pump and at least one gear. The well fluid is circulated past the material dislodging means for suspending the dislodged material
Data Source
AI summary
A downhole tool string forming a free end portion for performing an operation in a well having a well fluid, the string comprising towards the free end portion; a motor for delivering a rotational speed, a pump connected the motor for circulating the well fluid through a first port and a second port, a gear housing comprising a gear being driven by the pump and delivering a reduced rotational speed, a tool shaft rotatable by the gear at the reduced rotational speed; a reservoir around a section of the tool shaft for collecting dislodged material, and a material dislodging means connected to the tool shaft, wherein the gear housing further comprises a first fluid channel for providing fluid communication between the pump and the first port via the tool shaft being hollow, and a second fluid channel for providing fluid communication between the pump and second port via the reservoir.