Drillstring Agitator Spacing for Friction Reduction
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Solution Overview
Problem
In downhole drilling, especially in horizontal wellbores, the increasing length of drill pipes leads to significant friction issues due to contact with the wellbore wall and build-up of solid materials, which can cause the drill pipe to become stuck, and using multiple agitators can result in interfering vibrations that reduce effectiveness and potentially damage the drill pipe.
Innovation Solution
Determining and optimizing the effective distance between agitators in a drill string to minimize stress wave interference while maximizing the length of the drill pipe in a kinetic friction regime, using a combination of drill pipe, fluid, and operational parameters to position agitators effectively and adjust operational parameters such as amplitude and frequency to maintain movement and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple agitators are coupled to the drill pipe to minimize friction, then the friction reduction effectiveness is improved, but stress wave interference occurs which reduces agitator effectiveness and may damage the drill pipe
Solution Approach 1:
The drill pipe is divided into multiple sections, each equipped with an agitator at specific intervals. By segmenting the drill pipe and strategically positioning agitators along its length, the system maintains kinetic friction regime across different sections without allowing stress waves from one agitator to interfere with others, thus resolving the contradiction between friction reduction effectiveness and stress wave interference
Solution Approach 2:
Agitators are activated in a periodic sequence rather than simultaneously, creating alternating vibration patterns that prevent stress wave interference. This periodic activation allows each agitator to complete its vibration cycle before the next one activates, maintaining the kinetic friction regime while avoiding harmful interference patterns
2Length of moving object
If the length of the drill pipe is increased to reach producing formation in horizontal wellbores, then the drilling reach is improved, but friction and sticking force increase due to increased contact with wellbore wall
Solution Approach 1:
Agitators are positioned and activated in advance at specific locations along the drill pipe to preemptively create vibrations that prevent solid material buildup and maintain kinetic friction regime before static friction can develop. This preliminary action allows longer drill pipes to be used without experiencing excessive friction forces
Solution Approach 2:
Multiple agitators create controlled mechanical vibrations along the drill pipe, which prevent solid materials from building up around the pipe and maintain the drill pipe in a kinetic friction regime. This continuous vibration reduces the friction force despite the increased length and contact area with the wellbore wall
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 approach reduces frictional resistance, prevents pipe sticking, and maintains effective vibration patterns, allowing for more efficient and reliable drilling by ensuring that the drill pipe remains in a kinetic friction regime with reduced stress wave interference.
Implementation Method 1
agitators are sometimes coupled to the drill pipe to create fluctuations in fluid pressure that result in the drill pipe vibrations
Implementation Method 2
stress waves generated by the agitator can interfere with one another
Data Source
AI summary
A method comprising determining a property of a first section of drill pipe that is to connect a first agitator to a second agitator in a bottom hole assembly of a drill string, determining a distance between the first agitator and the second agitator based, at least in part, on the property of the first section of drill pipe, positioning the first agitator in the bottom hole assembly of the drill string, and positioning the second agitator in the bottom hole assembly of the drill string relative to the first agitator based, at least in part, on the distance.