Staged Pressure Restriction Devices for Wellhead Seal Wear

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Solution Overview

Problem

Wellhead stack assembly seal elements experience premature wear due to high differential pressures and mechanical action, leading to frequent maintenance and increased non-productive time in drilling operations.

Innovation Solution

The implementation of staged pressure restriction devices with multiple seal elements arranged in a cascading manner to distribute the differential pressure across each seal element, reducing wear and allowing for adjustable gaps to control pressure drops and fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single seal element is used to contain wellbore pressure, then the pressure containment function is achieved, but the seal element experiences high differential pressure leading to premature wear

Engineering Contradiction:

Improveseal element lifeVSAvoiddifferential pressure on seal element

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The pressure containment function is divided into multiple seal elements arranged in series, where each seal element handles a portion of the total differential pressure. This segmentation reduces the stress on each individual seal element, extending its operational life while maintaining overall pressure containment effectiveness.

Inventive Principle:

Principle #1Segmentation

2Reliability

If multiple pressure restriction devices are staged in series, then the differential pressure across each seal element is reduced, but the device complexity increases

Engineering Contradiction:

Improveseal element durabilityVSAvoidnumber of pressure restriction devices

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system is segmented into multiple pressure restriction devices with seal elements arranged in series, where each device handles a specific pressure stage. This segmentation distributes the differential pressure load across multiple components, reducing wear on each seal element while achieving reliable pressure containment through the staged configuration.

Inventive Principle:

Principle #1Segmentation

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 approach extends the life of seal elements, reduces pressure loads on bearings, and enables the use of thinner, lighter pressure restriction devices, potentially eliminating the need for chokes and improving drilling efficiency and reliability.

Implementation Method 1

reducing a differential pressure across a given seal element of a pressure restriction device by arranging multiple seal elements of multiple pressure restriction devices of an assembly in a staged manner such that a cascade of pressures is applied to the seal elements

Methodology Applied

Scientific EffectPressure differential distribution: Pressure Gradient

Implementation Method 2

Small gaps between the drill pipe and the seal elements can create a restriction and a pressure drop across each

Methodology Applied

Scientific EffectFluid flow restriction: Pressure Drop

Data Source

PatentUS9957774B2Pressure staging for wellhead stack assembly

Publication Date: 2018.05.01 HALLIBURTON ENERGY SERVICES INC

AI summary

A wellhead stack assembly is provided that includes pressure restriction devices. The pressure restriction devices are staged such that each pressure restriction device is coupled to another pressure restriction device for cascading pressure differentials across the pressure restriction devices. Each pressure restriction device includes an active element positionable about a drill pipe for controlling a gap between the drill pipe and the active element.