Mud Pulse Telemetry Tool Secondary Seal and Rotor Stator Design
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Solution Overview
Problem
Mud pulse telemetry systems in drilling operations face mechanical and abrasive wear issues due to high differential pressure requirements, leading to valve failure in negative pressure pulse generation, and require electrical connectivity for pulse frequency control.
Innovation Solution
A telemetry tool with a fluid pressure pulse generator featuring a stator and rotor design, including a tortuous flow path with restricted and expansion zones, and a secondary seal to reduce wear and eliminate the need for electrical connectivity by using a rotor and stator with radially extending projections to create pressure pulses in the drilling fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative pressure pulse valves are used to create pressure waves in drilling mud, then telemetry data can be transmitted to surface, but the valves are prone to mechanical wear and failure due to high differential pressure requirements
Solution Approach 1:
The patent inverts the conventional negative pressure pulse approach by using positive pressure pulses instead. The valve mechanism opens to allow mud flow, creating a positive pressure wave, then closes to create the pulse signal. This reversal eliminates the need for high differential pressure to open the valve, reducing mechanical wear and improving reliability.
Solution Approach 2:
The patent changes the pressure parameter from negative to positive by modifying the valve operation mode. Instead of requiring high differential pressure to open the valve (negative pulses), the system uses low differential pressure to open the valve and relies on valve closure to generate the pressure pulse signal, fundamentally changing the pressure regime.
2Productivity
If conventional valve mechanisms are used to generate pressure pulses, then data transmission is achieved, but the valves require frequent replacement due to abrasive wear from high pressure differentials
Solution Approach 1:
The patent inverts the conventional approach by using positive pressure pulses generated through valve opening and closing, rather than negative pulses requiring high differential pressure. This inversion maintains data transmission efficiency while extending valve service life by reducing mechanical stress and abrasive wear.
Solution Approach 2:
The patent converts the harmful effect of high differential pressure into a beneficial low differential pressure system. By using the valve closure event itself to generate the pressure pulse rather than requiring high pressure to open the valve, the system transforms what was a damaging condition into a gentle operating regime that extends component life.
3Ease of operation
If pulse generator motors are used to control pulse frequency, then precise frequency control is achieved, but electrical connectivity is required which complicates the system
Solution Approach 1:
The patent replaces the electrical motor-driven pulse generation system with a mechanically actuated valve system. The valve is controlled by mechanical means (such as a cam mechanism or direct mechanical actuation) that converts rotational motion into the opening/closing actions required for pulse generation, eliminating the need for electrical connectivity while maintaining frequency control capability.
Solution Approach 2:
The patent extracts and removes the electrical motor component from the pulse generation system. By separating the frequency control function from the electrical domain and implementing it through mechanical timing mechanisms, the system eliminates electrical connectivity requirements while preserving precise pulse frequency control.
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
The solution reduces mechanical wear, extends the life of seals, and allows for efficient generation of pressure pulses without electrical connectivity, enhancing the reliability and efficiency of mud pulse telemetry systems.
Implementation Method 1
The pressure pulses are achieved by changing the flow area and/or path of the drilling fluid as it passes the MWD tool in a timed, coded sequence, thereby creating pressure differentials in the drilling fluid
Implementation Method 2
A tortuous flow path with restricted and expansion zones
Data Source
AI summary
A telemetry tool comprising a pulser assembly, a primary seal, a fluid pressure pulse generator and a secondary seal. The pulser assembly comprises a housing and a driveshaft extending out of an opening in the housing. The primary seal surrounds and seals against the driveshaft to seal the opening in the housing. The fluid pressure pulse generator comprises a stator with a bore therethrough configured to fixedly attach to the housing or to a drill collar surrounding the fluid pressure pulse generator, and a rotor fixedly attached to the driveshaft. The driveshaft and rotor rotate relative to the fixed stator to generate pressure pulses in mud flowing through the fluid pressure pulse generator. The secondary seal is seated in the stator bore and surrounds and seals against a portion of the driveshaft extended out of the housing or a portion of the rotor to reduce the amount of mud, grit and debris impinging on the primary seal which could otherwise cause wear or damage the primary seal.