Downhole Tool Pump Placement for Compact Fluid Flow
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Solution Overview
Problem
Existing downhole tool designs for wells face challenges in providing fluid to operational bits due to the need for high rotational speed pumps, which occupy internal space and wear down quickly when used in small diameter wells, making it difficult to maintain a compact tool string with sufficient fluid flow.
Innovation Solution
A downhole tool string design featuring a motor unit, gear section, and pump unit where the pump is positioned between the gear section and operational tool, utilizing a reduction gear assembly and transition gear to achieve efficient fluid flow with a compact outer diameter, allowing the pump to expel fluid radially and suck it back through the drill bit, enabling fluid to be forced past the operational tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is arranged at the front end of the tool with a reduction gear, then the pump can provide fluid to the operational bit, but the tool string outer diameter increases and the gear section wears down quickly
Solution Approach 1:
The pump is repositioned from the front end to the rear end of the tool string, changing the spatial arrangement from a longitudinal configuration to a configuration where the pump operates in a different dimensional space relative to the operational tool. This allows the pump to drive fluid through the operational tool rather than directly to it, reducing the need for large-radius gear sections and minimizing tool string outer diameter while improving gear durability
Solution Approach 2:
The fluid itself acts as an intermediary medium between the pump and the operational tool. Instead of the pump directly driving the operational bit through a reduction gear, the pump drives fluid through the operational tool, and the fluid flow accomplishes the operational function. This eliminates the need for a direct mechanical connection and reduces gear section size and wear
2Volume of moving object
If the reduction gear section is made compact to fit in small diameter wells, then the tool string outer diameter decreases, but the gear section wears down very quickly
Solution Approach 1:
The direct mechanical drive function is extracted from the reduction gear system. Instead of the reduction gear directly driving the operational bit, the system extracts the driving function and replaces it with fluid power transmission. The pump drives fluid through the operational tool, eliminating the need for the reduction gear to handle high-stress direct drive operations, thereby reducing wear while maintaining compact dimensions
Solution Approach 2:
The mechanical reduction gear system is partially replaced with a fluid power system. The pump generates fluid flow that drives the operational tool through fluid pressure and flow rather than direct mechanical connection. This substitution reduces the mechanical stress on the gear section, decreasing wear while allowing the tool to maintain a compact outer diameter suitable for small diameter wells
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 allows for a smaller outer diameter tool string while maintaining effective fluid flow past the operational tool, reducing wear on the gear section and enabling efficient operation in small diameter wells by optimizing the arrangement of the pump and gear components.
Implementation Method 1
a pump unit (8) having a rotor shaft (9) rotated by the motor unit (3) for providing fluid around or past the operational tool (6)
Implementation Method 2
a gear section (5), an operational tool (6) having a tool shaft (7) rotated by the gear section (5) at a lower rotational speed than that of the rotational shaft
Data Source
AI summary
A downhole tool string comprising a motor unit (3) having a rotational shaft rotating with a rotational motor speed; a gear section; an operational tool having a tool shaft rotated by the gear section (5) at a lower rotational speed than that of the rotational shaft; and a pump unit (8) having a rotor shaft rotated by the motor unit (3) for providing fluid around or past an operational tool (6). The pump unit (8) is arranged between the gear section (5) and the operational tool (6).