Selective Agitation Downhole Tool with Flow Bypass
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Solution Overview
Problem
In directional drilling, it is challenging to advance a non-rotating drill string through a drilled bore, and existing agitation tools can restrict fluid flow and pressure, limiting their applicability and efficiency, especially when differential sticking occurs.
Innovation Solution
A fluid-actuated downhole tool with a flow-modifying valve arrangement and a Moineau principle positive displacement motor that can be selectively activated to induce agitation in the drill string, featuring a bypass mechanism to avoid pressure drops and flow restrictions, allowing for quick activation and deactivation to address specific drilling needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flow modifying arrangement is used to induce agitation in the drill string, then the rate of penetration and ability to free stuck sections is improved, but the fluid flow and pressure in the drill string are restricted and reduced
Solution Approach 1:
The valve arrangement is designed to be movable between different positions (first position for agitation, second position for normal flow). This dynamic configuration allows the system to switch between agitating mode where flow is restricted to create pressure pulses, and normal drilling mode where full flow is restored, thus resolving the contradiction between achieving agitation效果 and maintaining fluid flow.
Solution Approach 2:
The agitation mechanism operates by periodically cycling the valve arrangement between its first and second positions, creating pulsing pressure variations in the drill string. This periodic action generates the desired agitation effect for freeing stuck sections or improving rate of penetration, while allowing full fluid flow during the non-actuating portions of the cycle, thus resolving the flow restriction issue.
2Reliability
If a flow modifying arrangement is activated to induce agitation, then the drill string can be freed from differential sticking, but the pressure drop across the tool increases
Solution Approach 1:
The valve arrangement dynamically switches between a first configuration that creates pressure pulses for agitation and a second configuration that restores normal pressure conditions. When differential sticking occurs, the system activates the agitation mode to free the stuck section, then returns to the normal flow mode to minimize pressure drop, thus resolving the contradiction between reliability and pressure maintenance.
Solution Approach 2:
The system maintains continuous drilling operation by quickly switching between agitation and normal flow modes. The agitation action is applied only when needed (when sticking is detected), allowing the system to maintain continuous productive action without sustained pressure drops, thus resolving the contradiction between freeing stuck sections and maintaining pressure.
Data Source
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AI summary
A fluid actuated downhole tool for inducing movement of a downhole apparatus is described. The tool comprises a body for coupling to downhole apparatus, the body being adapted to accommodate flow of fluid therethrough and including a flow-modifying arrangement for modifying the flow of fluid through the body. The flow-modifying arrangement is configurable in an inactive configuration and in an active configuration. The fluid activated tool is selectively operated from the surface by varying an operating condition which causes the flow through the tool to either bypass or flow through the flow-modifying arrangement to induce movement of the downhole apparatus.