Downhole Pulsation System Friction Reduction
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Solution Overview
Problem
Conventional downhole drilling systems face challenges in reducing friction on tool strings, particularly in horizontal drilling, where coiled tubing is prone to buckling and friction lock-up, and existing cavitation devices lack controlled, tunable pressure pulses.
Innovation Solution
A novel downhole pulsation system utilizing a valve and rotor-stator assembly that generates controlled pressure pulsations by intermittently obstructing fluid flow through a mandrel cap and stator, reducing friction on tool strings and facilitating advancement through the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If coiled tubing is used in downhole operations, then flexibility and ease of deployment are improved, but susceptibility to buckling and friction lock-up increases
Solution Approach 1:
The rotor-stator assembly generates mechanical vibrations and pressure pulsations in the drilling fluid that propagate through the coiled tubing. These vibrations prevent the tubing from buckling by maintaining dynamic motion and prevent friction lock-up by periodically breaking static friction contacts with the wellbore wall, enabling reliable operation of flexible coiled tubing in extended reach applications
Solution Approach 2:
The rotor-stator assembly creates periodic pressure pulsations by rotating the rotor lobes within the stator lobes, generating cyclic fluid displacement. This periodic action translates into rhythmic vibrations transmitted through the coiled tubing, continuously preventing buckling and periodically overcoming static friction to maintain advancement capability
2Object-affected harmful factors
If conventional cavitation or vibration devices are used to assist BHA advancement, then friction reduction is achieved, but controlled and tunable pressure pulse capability is lacking
Solution Approach 1:
The rotor-stator assembly allows control of pressure pulse frequency and amplitude by adjusting rotor rotation speed and lobe geometry parameters. The frequency is directly proportional to rotor speed, and amplitude is controlled by the volume displacement of rotor lobes, providing tunable and controllable pressure pulsations for optimized friction reduction
Solution Approach 2:
The system uses hydraulic principles by rotating the rotor within the stator to trap and displace drilling fluid, generating pressure pulsations. The fluid acts as the working medium to transmit mechanical energy from the rotor-stator interaction to the BHA, providing controlled and tunable pressure pulses through hydraulic action
3Force
If drill string weight is increased to overcome friction in horizontal drilling, then friction overcoming capability is improved, but equipment complexity and cost increase
Solution Approach 1:
The system replaces the mechanical approach of increasing drill string weight with a dynamic vibration-based approach. The rotor-stator assembly generates pressure pulsations that create vibrational forces to overcome static friction, substituting heavy mechanical weight with dynamic fluid-driven vibrations, thereby reducing equipment complexity and cost
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 system effectively reduces friction on tool strings, preventing lock-up and enabling further advancement in challenging drilling conditions by creating controlled pressure pulses, thereby improving drilling efficiency and preventing buckling of coiled tubing.
Implementation Method 1
generates controlled pressure pulsations by intermittently obstructing fluid flow
Implementation Method 2
intermittently obstructing fluid flow through a mandrel cap and stator
Implementation Method 3
reducing friction on tool strings, preventing lock-up and enabling further advancement
Implementation Method 4
create a pulsation or vibration at the BHA to assist in advancement through the earth
Data Source
AI summary
A valve system utilizable with a downhole tool or pulsation assembly for controlling the assembly to reduce friction on a drill string by generating pressure pulsations. The system can include a mandrel cap, and a valve. The valve can include a first end section, a valve bore defined along a longitudinal axis therethrough, one or more ports defined laterally through a sidewall of the valve and in communication with the valve bore, and a second end section defining one or more cavity sections in communication with the valve bore. At least a portion of the valve can be receivable in the cap bore, and the valve bore can be configured to receive fluid from the sub bore or the drill string. The cavity sections can be configured between an open position allowing fluid to pass therethrough and a closed position preventing fluid to pass therethrough.