Seabed Template Chuck for Offshore Drilling Heave Compensation
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Solution Overview
Problem
Offshore drilling using surface-mounted equipment experiences displacement and force variations due to heave motion compensators, leading to soil disturbances during geotechnical site investigations, as these compensators are not ideal for maintaining a stationary drill bit, especially when drilling in hard formations or at shallow water depths.
Innovation Solution
The offshore drilling installation employs a seabed template with wedge-shaped clamping means, including a chuck with vertical drive mechanisms, such as hydraulic cylinders, to securely clamp and rotate the drill string, allowing for controlled downward thrust and accommodating various drill string diameters, enabling efficient drilling in hard formations and reducing the need for excessive drill string weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If surface-mounted drilling equipment with heave motion compensator is used, then drilling can be performed from the platform, but displacement and force variations occur at the drill bit due to heave motion errors
Solution Approach 1:
Instead of compensating for heave motion at the surface level, the invention inverts the approach by placing the clamping means at the seabed level. The drill string is clamped at the seabed template rather than being controlled from the surface platform, thereby eliminating the transmission of heave motion errors to the drill bit.
Solution Approach 2:
The seabed template acts as an intermediary element between the drill string and the seabed. It provides a stable reference frame at the seabed level, isolating the drilling operation from surface heave motions and providing precise positional control at the drill bit location.
2Strength
If drill string weight is increased to drill in hard formations, then drilling capability in hard formations improves, but drill string becomes more prone to buckling due to long unsupported length
Solution Approach 1:
Instead of relying on the weight of the long drill string to provide downward thrust, the invention applies downward thrust at the seabed level through the vertical drive means in the chuck. This eliminates the buckling problem by providing support and thrust at the bottom rather than relying on the self-weight of the entire drill string.
Solution Approach 2:
The invention replaces the mechanical system of relying on drill string weight for downward thrust with an active drive system (hydraulic or electric motor) located in the chuck at the seabed. This substitution allows controlled application of downward force without the instability associated with long, unsupported drill strings.
3Strength
If chuck with vertical drive means is used, then downward thrust for hard formation drilling is improved, but device complexity increases
Solution Approach 1:
The chuck at the seabed is designed to perform multiple functions: clamping the drill string, enabling rotation, and providing vertical drive means for downward thrust. This multi-functionality reduces the need for separate systems and justifies the increased complexity by consolidating multiple capabilities in a single integrated component.
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 minimizes displacement and force variations at the drill bit, allowing for better control and efficient drilling in hard formations and shallow water, while enabling continuous operation and easy re-entry of the drill string, even in challenging weather conditions.
Implementation Method 1
wedge-shaped clamping means (35) are slidably connected with a wedge-shaped backing ring (36), wherein their contacting surfaces are oblique with reference to the longitudinal direction of the drill string and tapering upwards when the wedge-shaped clamping means engage said drill string
Implementation Method 2
The drive means for the chucks 11, 12 are embodied as hydraulic cylinder or cylinders 13, 14 connecting the chucks 11, 12 with the seabed template 26
Data Source
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AI summary
Offshore drilling installation comprising a platform selected from the group comprising a vessel, a pontoon, a jack-up, and further comprising a drill string drivingly connected with said platform and optionally provided with a heave motion compensator, wherein at its lower end the drill string is provided with a drill bit, and wherein a seabed template suspended with lift wires from the platform is placed on a seabed, and wherein clamping means mounted in the seabed template are provided for fixing the drill string relative to the seabed template, which clamping means are embodied as a chuck which is arranged for clamping the drill string whilst enabling the drill string's rotation.