Hydraulic Interlock for Casing Gripper and Spider
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Solution Overview
Problem
In the process of running casing into a well or drilling with casing, there is a risk of the casing string accidentally dropping due to inadvertent release of hydraulic fluid pressure, which can lead to disastrous consequences, as the weight of the casing string can prevent the slips from releasing or moving upward even with applied hydraulic pressure.
Innovation Solution
A hydraulic safety circuit that monitors and controls the hydraulic fluid pressure at both the spider and gripper, ensuring that pressure is only released if it is already being applied to hold the gripping members in position, using pilot-operated check valves and a sensing mechanism with a limit switch valve to prevent accidental release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic fluid pressure is applied to the spider slips to hold the casing string, then the casing string is securely supported, but if release pressure is inadvertently applied, the casing string may accidentally drop
Solution Approach 1:
The hydraulic interlock system applies preliminary anti-action by requiring apply pressure to be active before release pressure can be applied to the spider. The interlock valve blocks the release line to the spider unless apply pressure is present at the gripper, preventing inadvertent release before the gripper is ready to support the casing string.
Solution Approach 2:
The interlock valve acts as an intermediary component between the gripper hydraulic system and the spider hydraulic system. It mediates the interaction by using apply pressure from the gripper side as a control signal to enable or disable release pressure to the spider, creating a safety interlock mechanism.
2Reliability
If hydraulic fluid pressure is applied to the gripper to hold the gripping members, then the additional joint is securely gripped, but if release pressure is inadvertently applied, the gripping members may accidentally release
Solution Approach 1:
The hydraulic interlock system applies preliminary anti-action by requiring apply pressure to be active before release pressure can be applied to the gripper. The interlock valve blocks the release line to the gripper unless apply pressure is present at the spider, preventing inadvertent release before the spider is ready to support the casing string.
Solution Approach 2:
The interlock valve acts as an intermediary component between the spider hydraulic system and the gripper hydraulic system. It mediates the interaction by using apply pressure from the spider side as a control signal to enable or disable release pressure to the gripper, creating a safety interlock mechanism.
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 safety circuit effectively prevents accidental release of the casing string by ensuring that hydraulic fluid pressure is only directed to the release position if it is already being applied to hold the gripping members in place, thereby reducing the risk of the casing string sliding downward into the well.
Implementation Method 1
The safety valves may be pilot operated check valves. A spider pilot line extends from the gripper apply line to the spider check valve to deliver hydraulic fluid pressure from the gripper apply line to the spider check valve to move the spider check valve to an open position.
Data Source
AI summary
A system for deploying a string of pipe from a drilling rig into a well includes a spider for mounting on a rig floor and a pipe gripper attached to the top drive. A hydraulic safety circuit monitors hydraulic fluid pressure at an apply port of the gripper and prevents hydraulic fluid pressure from being directed to move the slips to the released position if hydraulic fluid pressure is not already present at the apply port of the gripper. The safety circuit also monitors hydraulic fluid pressure at the apply port of the spider and prevents release hydraulic fluid pressure from being directed to move the gripping members to the released position if apply hydraulic fluid pressure is not already present at the apply port of the spider.