External Flow Switch for Repeated Downhole Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current hydraulic actuation mechanisms for downhole tools are expensive, time-consuming, and often limited to one-time use, making it difficult to repeatedly actuate and deactuate tools without breaking the drill string or tripping the tool out of the borehole, especially in near-bit deployments during drilling operations.
Innovation Solution
A pressure-activated flow switch is deployed externally to the downhole tool, allowing the reaming block to translate between radially retracted and extended positions in response to differential pressure, enabling repeated actuation and deactuation without obstructing the drilling fluid flow and allowing deployment near the drill bit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireline retrieval of a plug is used to create differential pressure, then the underreamer can be actuated, but the operation becomes expensive and time-consuming requiring concurrent use of wireline or slick line assemblies
Solution Approach 1:
The system uses the drilling fluid flow itself to actuate the underreamer through a flow switch mechanism. The differential pressure generated by the drilling fluid flowing through the flow bore automatically opens the flow switch and extends the reaming block, eliminating the need for external wireline or slick line operations. This self-actuating mechanism significantly reduces actuation time and operational complexity.
2Reliability
If shear pins or ball drop mechanisms are used, then the downhole tool can be actuated, but they are generally one-time or one-cycle mechanisms that do not allow for repeated actuation and deactuation
Solution Approach 1:
The flow switch mechanism is designed to be dynamically reversible. The flow piston can move between closed and open positions based on differential pressure conditions, allowing the reaming block to be extended and retracted multiple times. This dynamic mechanism enables repeated actuation and deactuation cycles without the tool string breaking or the tool needing to be tripped out of the borehole, providing versatility for multiple reaming operations.
3Reliability
If ball drop mechanisms are used, then the downhole tool can be actuated, but they require that the drill string have an unobstructed through bore extending from the surface to the ball seat
Solution Approach 1:
The flow switch is deployed entirely external to the central flow bore, in an annular region between the tool body and tool mandrel. This extraction of the flow switch from the central bore path preserves the cross-sectional area of the flow bore, providing no obstruction to drilling fluid flow. This allows the tool to be deployed low in the BHA near the drill bit without requiring an unobstructed through bore from the surface.
4Ease of operation
If the flow switch is deployed internally within the flow bore, then it can control fluid flow, but it would obstruct the drilling fluid flow and increase pressure drop and erosion
Solution Approach 1:
The flow switch is deployed entirely external to the central flow bore, in an annular region between the tool body and tool mandrel. This extraction of the flow switch from the central bore path preserves the cross-sectional area of the flow bore, providing no obstruction to drilling fluid flow. This minimizes both the pressure drop through the tool and erosion of internal tool components during use.
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 solution allows for repeated actuation and deactuation of downhole tools without breaking the drill string, minimizes pressure drop and erosion, and enhances operational certainty by eliminating inadvertent actuation and deactuation, while preserving the cross-sectional area for drilling fluid flow.
Implementation Method 1
The flow piston is configured to translate from the closed position to the open position when a differential pressure between the flow bore of the downhole tool and a chamber of the downhole tool exceeds a predetermined threshold
Implementation Method 2
The block assembly is configured to translate between radially retracted and radially extended positions in response to differential pressure
Data Source
AI summary
A downhole tool includes a pressure activated flow switch for selectively actuating and deactuating a device, such as a reaming block. The flow switch is deployed external to the flow bore and includes a flow piston configured to reciprocate between axially opposed open and closed positions such that the device is actuated when the flow piston is in the open position and deactuated when the flow piston is in the closed position. The flow piston is configured to translate from the closed position to the open position when a differential pressure exceeds a predetermined threshold. The flow piston may be further configured to remain in the open position at differential pressures less than the threshold.