Agitator and Shock Tool for Drill String Friction Mitigation
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Solution Overview
Problem
Directional drilling faces issues such as frictional drag and erratic torque due to frictional engagement between the drill string and the formation, leading to reduced penetration rates and potential damage, particularly in slide drilling where the lack of rotation exacerbates these problems, and existing friction tools require complex reassembly and fluid flow management.
Innovation Solution
A downhole agitator tool that generates controlled vibrations using pressure pulses and a shock tool with Belleville springs to break static friction, allowing for adjustable vibration frequency and amplitude without the need for continuous fluid flow, and a dart system for selective activation and fine-tuning of the tool's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a friction tool is used to generate vibrations to overcome friction and hole drag, then the rate of penetration and drill string performance improve, but the tool requires continuous drilling fluid flow to operate, which impacts overall drilling operation and requires complex fluid flow management
Solution Approach 1:
The patent employs a friction tool that generates mechanical vibrations through a vibrating element actuated by drilling fluid pressure variations. The vibrations are transmitted to the drill string to reduce friction and hole drag, improving rate of penetration while maintaining controlled operation without requiring continuous fluid flow adjustments
Solution Approach 2:
The friction tool utilizes periodic pressure variations in the drilling fluid to actuate the vibrating element. This periodic action creates controlled vibrations that mitigate friction effects intermittently, reducing the need for continuous fluid flow management while maintaining drilling productivity
2Adaptability or versatility
If the drill string is not rotated during slide drilling to effect direction changes, then directional control is achieved, but significant friction results from the lack of rotation, reducing penetration rate and increasing weight-on-bit requirements
Solution Approach 1:
The friction tool generates mechanical vibrations that are transmitted to the drill string during slide drilling operations. These vibrations reduce the friction between the stationary drill string and the formation, enabling directional changes while maintaining adequate penetration rates and reducing weight-on-bit requirements
3Reliability
If the friction tool is run during the entirety of the drilling operation, then friction mitigation is continuous, but it is unnecessary or problematic during certain stages such as shallow depth or within casing where added vibration is undesirable
Solution Approach 1:
The patent introduces a controllable valve system as an intermediary between the drilling fluid flow and the vibrating element. This valve allows selective activation and deactivation of the friction tool based on drilling conditions, providing operational flexibility to avoid unnecessary vibrations during stages where they are problematic while maintaining friction mitigation when needed
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 effectively reduces friction, improves weight transfer, and enhances drill string dynamics, allowing for more efficient drilling with reduced stick-slip and borehole deviation issues, while minimizing the need for continuous tool operation and fluid flow management complexities.
Implementation Method 1
shock tool with Belleville springs to break static friction
Implementation Method 2
generates controlled vibrations using pressure pulses and a shock tool with Belleville springs
Implementation Method 3
generates controlled vibrations using pressure pulses
Implementation Method 4
driven by the variations in the pressure of drilling fluid flowing through the friction tool
Data Source
AI summary
A shock and agitator tool assembly vibrates a drill string to overcome stick slip and other friction-based problems that may occur during directional drilling. The agitator tool portion of the assembly, which can be used without the shock tool, allows for controlled activation and deactivation of the agitator tool by the use of one or more darts pumped downhole. The darts can be retrieved with a wireline tool. When activated, the agitator portion creates alternating pressure pulses. These pulses cause axial movement of the drill string above the agitator. A shock tool is described which utilizes a telescoping mandrel to amplify the axial movement created by the agitator tool.