Switchable Circulating Tool Piston Dynamics for Multi-Cycle Bore Access
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Solution Overview
Problem
Existing circulating subs in the oil and gas industry face limitations such as single-use operation, blockage of drop balls, unpredictable fluid pressure, and turbulent flow, which restrict efficiency and reliability in cuttings removal and tool passage.
Innovation Solution
A pressure-activated circulating tool with a piston assembly and indexing mechanism that allows multiple cycles between pump-thru and circulation modes, maintaining an uninterrupted bore for tool passage and reducing turbulent flow through a split piston design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional circulating sub with a sleeve and shear pin is used to increase fluid flow rate for cuttings removal, then fluid flow rate to the annulus is improved, but the tool can only be operated once and requires surface retrieval for reconfiguration
Solution Approach 1:
The piston assembly is designed to move dynamically between different positions within the circulating sub based on fluid pressure. The piston can be positioned to either block or open the central throughbore, allowing the tool to switch between pump-thru mode and circulation mode. This dynamic positioning enables multiple operational cycles without requiring surface retrieval, as the piston automatically responds to pressure changes from dropped balls or fluid flow variations.
2Productivity
If the central bore is sealed to jet fluid for cleaning purposes, then cuttings removal efficiency is improved, but passage of drop balls and logging equipment is blocked
Solution Approach 1:
The piston assembly provides a dynamic sealing mechanism that can be positioned to block or open the central throughbore as needed. When jetting is required, the piston blocks the bore to direct all fluid through the radial ports for maximum cleaning efficiency. When tool passage is needed, the piston repositions to open the bore, allowing drop balls and logging equipment to pass freely. This dynamic adaptation resolves the contradiction between cutting removal efficiency and tool passage capability.
3Duration of action of moving object
If a deformable drop ball is used to actuate the circulating sub multiple times, then operational cycles are increased, but the ball blocks the bore below the sub and prevents tool passage
Solution Approach 1:
The invention extracts the actuation function from the drop ball itself and transfers it to the piston assembly. Instead of relying on the ball to physically pass through and deform to actuate the sub, the ball simply needs to reach the piston and apply pressure to move it. The piston then performs the sealing and actuation functions, while the ball continues its downward path unimpeded. This separation of actuation and passage functions allows multiple operational cycles without blocking the bore for subsequent tool passage.
4Power
If fluid pressure is increased to operate the PDM, then motor operation is improved, but cuttings removal efficiency decreases due to insufficient flow rate
Solution Approach 1:
The circulating sub provides a dynamic flow control mechanism that can adjust the distribution of fluid between the PDM and the annulus. When PDM operation is required, the piston positions to open the central throughbore, directing fluid to the motor. When cuttings removal is prioritized, the piston blocks the bore and directs fluid through radial ports to the annulus. This dynamic switching allows optimization of fluid distribution based on operational requirements, resolving the contradiction between PDM power and cuttings removal efficiency.
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
Enables efficient, multi-cycle operation with reduced abrasion wear and improved fluid flow for cuttings removal, allowing for the passage of tools like drop balls and logging equipment while maintaining PDM operation without requiring surface retrieval.
Implementation Method 1
the piston assembly movable in response to pressure differential between fluid in the central throughbore and fluid in the annulus
Implementation Method 2
an indexing mechanism converting axial movement of the piston assembly into rotational movement to index between operational configurations
Data Source
AI summary
A circulating tool for use in drilling a bore hole, the tool including a plurality of pistons which, by the activation of fluid pressure, move between a first configuration in which a side port of the tool is covered by a piston and a second configuration in which two adjacent pistons separate across the port to allow fluid to jet from the port. In the first configuration, the tool has a continuous cylindrical bore to allow the passage of other tools through the tool, while a flapper valve closes the bore in the second configuration to achieve maximum jetting of fluid from the tool. A third or intermediate configuration is also described so that the tool is operable to switch multiple times between the configurations via an indexing mechanism.