Subsea Slanted Wellhead System for Shallow Lateral Drilling
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Solution Overview
Problem
Conventional directional drilling techniques are inadequate for drilling lateral wellbores at shallow sub-bottom depths below water bodies, as they struggle to effectively reorient the wellbore trajectory from vertical to horizontal, leading to insufficient wellbore deviation and impractical deployment of long, large-diameter devices.
Innovation Solution
A subsea wellbore intervention tool conveyance system featuring a dual injector head system with an upper injector for retrieving and a lower injector for inserting a drill string, utilizing a spoolable tube or coiled tubing, and a subsea template with an inclined wellhead to facilitate horizontal wellbore drilling at shallow depths, reducing wellbore deviation build rate and enabling efficient fluid extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional directional drilling techniques are used, then the drilling process can be performed with standard equipment, but the wellbore trajectory cannot be effectively reoriented from vertical to horizontal at shallow sub-bottom depths
Solution Approach 1:
The patent introduces a slanted wellhead system that changes the entry angle dimension of the wellbore. By positioning the wellhead at a predetermined slant angle relative to the vertical axis, the system enables lateral wellbore trajectories at shallow depths without requiring extreme trajectory deviation from vertical entry, thus resolving the contradiction between trajectory reorientation capability and shallow depth adaptability
Solution Approach 2:
The system changes the geometric parameter of the wellhead entry angle from vertical (0 degrees) to a predetermined slant angle. This parameter modification allows the wellbore to achieve lateral trajectory at shallow depths while maintaining effective deviation control, addressing the limitation of conventional vertical drilling techniques
2Device complexity
If conventional vertical wellhead systems are used, then the system structure remains simple, but the wellbore deviation build rate becomes excessive for shallow lateral drilling
Solution Approach 1:
By introducing a slanted wellhead configuration that changes the vertical entry dimension to an inclined entry dimension, the system reduces the required wellbore deviation build rate. The predetermined slant angle provides an initial lateral component that decreases the deviation angle needed from the vertical, achieving better deviation control without excessive complexity
3Productivity
If multiple lateral wellbores are drilled from a single pilot wellbore, then the number of pilot wellbores is reduced, but the surface area and environmental impact are still significant
Solution Approach 1:
The slanted wellhead system with dual injector heads creates a multi-functional platform that can efficiently drill multiple lateral wellbores from a single pilot wellbore. The system's capability to handle multiple laterals from one vertical entry point maximizes the utility of each pilot wellbore, reducing both the number of pilots needed and the surface area occupied, thereby addressing the contradiction between productivity and surface footprint
Data Source
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AI summary
A wellbore intervention tool conveyance system includes an upper pipe injector disposed in a pressure tight housing. The upper injector has a seal element engageable with a wellbore intervention tool and disposed below the injector. The upper housing has a coupling at a lower longitudinal end. A lower pipe injector is disposed in a pressure tight housing, the lower housing has well closure elements disposed above the lower pipe injector. The lower housing is configured to be coupled at a lower longitudinal end to a subsea wellhead. The lower housing is configured to be coupled at an upper longitudinal end to at least one of (i) a spacer spool disposed between the upper pipe injector housing and the lower pipe injector housing, and (ii) the lower longitudinal end of the upper pipe injector housing.