Coiled Tubing Pulsers for Friction Reduction in Horizontal Wells
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Solution Overview
Problem
Current coiled tubing measurement while drilling (CT-MWD) technologies face inefficiencies in horizontal well completions due to reduced maximum weight on bit and increased frictional drag at greater depths, limiting lateral reach and plug milling efficiency in unconventional shale plays.
Innovation Solution
The CT-MWD-FTD tool employs a pulser system with a pilot valve actuator assembly that generates controlled, repeatable fluid pulses using magneto-electric and/or turbine energy, reducing friction and enhancing axial agitation within the coiled tubing, allowing for intelligent data collection and real-time adjustments to optimize weight-on-bit and penetration rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coiled tubing is used for plug removal in horizontal wells, then operational flexibility is improved, but milling efficiency decreases at increased lateral depths due to reduced weight on bit and increased frictional drag
Solution Approach 1:
The system employs periodic pulsing actions through a pulser device that creates cyclic pressure variations in the drilling fluid. These periodic pulses generate axial agitation and vibration in the coiled tubing, which reduces frictional drag and enhances the transmission of weight on bit to the milling tool, thereby improving milling efficiency at extended lateral depths while maintaining operational flexibility
Solution Approach 2:
The system dynamically changes operational parameters including pulse frequency, pulse amplitude, and flow rate to optimize performance at different lateral depths. By adjusting these parameters, the system compensates for reduced gravitational effects and increased friction, maintaining effective weight on bit and milling efficiency throughout the horizontal section
2Stability of the object's composition
If coiled tubing outer diameter is increased to reduce buckling, then structural stability is improved, but frictional drag increases due to larger contact surface area
Solution Approach 1:
The pulser generates periodic axial vibrations that reduce the effective contact time between the coiled tubing and wellbore wall, thereby reducing frictional drag. This allows the use of larger diameter tubing for structural stability without proportionally increasing friction losses, as the pulsing action periodically lifts the tubing off the wall during each vibration cycle
Solution Approach 2:
The system utilizes mechanical vibration induced by the pulser to reduce frictional resistance. The vibrational motion creates a dynamic interaction between the coiled tubing and wellbore wall, reducing the static friction that would otherwise prevent effective load transmission and allowing larger diameter tubing to be used with reduced frictional penalty
3Object-affected harmful factors
If coiled tubing outer diameter is decreased to reduce friction, then frictional drag is reduced, but buckling increases due to reduced structural rigidity
Solution Approach 1:
The periodic pulsing action provides dynamic support to the coiled tubing by creating upward forces during each pulse cycle that counteract the buckling tendency. This allows smaller diameter tubing with lower friction to be used effectively, as the pulsing provides intermittent structural support without requiring increased diameter for rigidity
Solution Approach 2:
The pulser generates upward reactive forces that counterbalance the downward gravitational load and buckling tendencies. By creating periodic counter-forces through pressure pulses, the system compensates for the reduced structural rigidity of smaller diameter tubing, allowing friction reduction without proportionally increasing buckling risk
4Length of moving object
If additional coiled tubing is sent from surface to increase lateral reach, then extended reach is achieved, but transmission of load to bit becomes longer and more inconsistent due to increased static loads
Solution Approach 1:
The periodic pulsing action creates cyclic compression waves that propagate through the coiled tubing string, continuously refreshing the load transmission path. This periodic reinforcement compensates for the increased length and static load effects, maintaining more consistent weight on bit transmission over extended lateral reaches by periodically overcoming friction and elastic deformation in the tubing string
Solution Approach 2:
The vibrational energy from the pulser propagates through the coiled tubing, reducing the effective stiffness and damping effects over long distances. This allows load transmission to remain more consistent despite increased length, as the vibration maintains energy propagation and reduces the cumulative effect of friction and elastic deformation along the extended tubing string
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 enables extended reach and improved plug milling efficiency by minimizing friction, reducing coiled tubing fatigue, and optimizing power usage through intelligent pulser control, resulting in faster well production and reduced operational time.
Implementation Method 1
The CT-MWD-FTD tool employs a pulser system with a pilot valve actuator assembly that generates controlled, repeatable fluid pulses using magneto-electric and/or turbine energy
Implementation Method 2
The telemetric pulses produced by the pulser also create momentary axial loads on the bottom hole assembly (BHA) and along the coiled tubing string, thus reducing friction and enhancing extended reach within the wellbore
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
An apparatus and system for generating pressure pulses for enhancing and completing a well bore within a coiled tubing assembly including: a CT-MWD-FTD tool longitudinally and axially positioned within the center of a main valve assembly including a main valve. The drilling fluid is subsequently split into both an inlet main fluid stream and a pilot fluid stream, wherein the pilot fluid stream subsequently flows such that the pilot fluid recombines with the main flow stream to become a main exit fluid flow. The main exit fluid flow then proceeds toward a motor housing wherein one or more annular pressure sensors measure the pressure of fluid flow with sensors that send signals to a Digital Signal Processor (DSP) that controls flow throttling devices which generate controllable, large, rapid and measurable energy pulses.