Interchangeable Subsea Wellhead Feed-Thru Alignment

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Solution Overview

Problem

The existing methods for connecting subsea lower marine riser packages (LMRPs) to lower blowout preventer stacks require dry pre-assembly and custom fitting, which is time-consuming, costly, and limits interchangeability, leading to increased manufacturing time and downtime due to the need for unique, non-interchangeable components.

Innovation Solution

The method involves manufacturing LMRPs and lower BOP stacks separately without prior dry fitting, using oversized mounting holes and floating feed-thru components to allow for precise alignment and engagement undersea, facilitated by precision measuring devices like laser trackers to ensure accurate positioning of mating halves within predetermined reference datums.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If dry pre-assembly and custom fitting are used to connect LMRP to lower BOP stack, then alignment precision is improved, but manufacturing time and device complexity increase

Engineering Contradiction:

Improvealignment precisionVSAvoidmanufacturing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-positioning the feed-thru components within oversized mounting holes during separate manufacturing of LMRP and lower BOP stack. The components are held in place with temporary support structures that allow for easy removal and repositioning, enabling precise alignment to be achieved during subsea assembly without requiring time-consuming dry pre-assembly of the entire system.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the assembly process by allowing LMRP and lower BOP stack to be manufactured and prepared separately with their respective feed-thru components pre-positioned. This segmentation eliminates the need for custom fitting of the complete assembly and enables interchangeable components to be assembled independently and then connected at subsea location.

Inventive Principle:

Principle #1Segmentation

2Reliability

If custom fitting is performed for each LMRP-BOP stack pair, then connection reliability is improved, but interchangeability and productivity deteriorate

Engineering Contradiction:

Improveconnection reliabilityVSAvoidinterchangeability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by designing standardized feed-thru components with consistent mounting hole patterns and interface specifications that can be used across multiple LMRP and lower BOP stack assemblies. The oversized mounting holes accommodate variations in component positioning while maintaining reliable connections, enabling the same components to be interchanged between different assemblies without custom fitting.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the parameter of mounting hole size from standard precision holes to oversized holes that provide tolerance for alignment variations. This parameter change allows feed-thru components to be positioned within a range of tolerances while still achieving reliable connections, thereby enabling interchangeability without sacrificing connection reliability.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If traditional mounting holes are used, then manufacturing simplicity is improved, but alignment precision and interchangeability deteriorate

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidalignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the mounting hole size adaptable - using oversized holes that provide dynamic adjustment capability during assembly. The enlarged hole dimensions allow components to be positioned and adjusted within tolerance ranges, providing the flexibility needed for precise alignment while maintaining simple manufacturing processes that don't require high-precision hole drilling.

Inventive Principle:

Principle #15Dynamics

4Manufacturing precision

If floating feed-thru components are used, then alignment tolerance is improved, but device complexity increases

Engineering Contradiction:

Improvealignment toleranceVSAvoiddevice complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies self-service by designing floating feed-thru components that automatically self-align during the lowering and engagement process. The components float within oversized mounting holes and use their own weight and the engagement force to achieve proper alignment, eliminating the need for complex external alignment mechanisms or devices.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8127852B2Interchangeable subsea wellhead devices and methods

Publication Date: 2012.03.06 HYDRIL USA DISTRIBUTION LLC

AI summary

A method for connecting a lower marine riser package to a lower blowout preventer stack. The method includes lowering a frame of the lower marine riser package toward a frame of the lower blowout preventer stack such that a first half of a feed-thru component contacts a second half of the feed-thru component; floating at least one of the first half of the feed-thru component or the second half of the feed-thru component while the frame of the lower marine package is further lowered toward the frame of the lower blowout preventer stack; and engaging the first half of the feed-thru component to the second half of the feed-thru component after further lowering the lower marine riser package toward the lower blowout preventer stack.