Nested Safety Valve Delayed Closure via Choke

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Solution Overview

Problem

Subsurface safety valves in oil and gas wells can fail, leading to costly and time-consuming repairs or replacements, especially when hydraulic pressure is lost, and there is a need for an efficient method to provide hydraulic pressure to wireline retrievable safety valves for proper operation.

Innovation Solution

A subsurface flow control system with a primary and secondary safety valve configuration, where the secondary valve is time-delayed to close relative to the primary valve, allowing a smaller, less robust wireline retrievable safety valve to be used as a backup, with a choke mechanism to control the delay in fluid pressure reduction, ensuring the primary valve is fully closed before the secondary valve begins to close.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If a wireline retrievable safety valve (WLRSV) is installed as a backup to a tubing retrievable safety valve (TRSV), then the cost and time of replacing a malfunctioning TRSV is reduced, but providing hydraulic pressure to the WLRSV for proper operation becomes complex

Engineering Contradiction:

Improveease of repairVSAvoiddevice complexity

Core Design Contradiction:

Ease of repairVSDevice complexity

Solution Approach 1:

The WLRSV is nested inside the TRSV, with the WLRSV disposed within the valve body of the TRSV. This nesting arrangement allows the smaller WLRSV to be housed within the larger TRSV structure, enabling cost-effective backup functionality while sharing the same hydraulic control line and valve body space.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

A choke is introduced as an intermediary component in the hydraulic control line to the WLRSV. This choke delays the pressure reduction signal, ensuring the TRSV closes before the WLRSV. The intermediary choke simplifies the hydraulic arrangement by using a single control line while maintaining sequential closure through pressure delay.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the secondary safety valve closes immediately when hydraulic pressure is lost, then well control is maintained, but the valve experiences high operational stress and may suffer further damage

Engineering Contradiction:

ImprovereliabilityVSAvoidstrength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The TRSV is designed to close first as a preliminary action before the WLRSV closes. By losing hydraulic pressure, the TRSV closes initially, reducing flow and pressure to the WLRSV before the WLRSV closes. This preliminary closure of the TRSV protects the WLRSV from high operational stress during the closing process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system provides beforehand cushioning by having the TRSV close first, which reduces the flow and pressure that the WLRSV will experience when it closes. This prior action cushions the WLRSV from the full force of high-pressure fluid, preventing further damage to the already malfunctioning valve.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If hydraulic pressure is lost to close the safety valves, then well control is achieved, but the closure occurs too quickly causing water hammer effects and potential damage

Engineering Contradiction:

ImprovereliabilityVSAvoidobject-affected harmful factors

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The TRSV closes first as a preliminary action, reducing flow and pressure before the WLRSV closes. This sequential closure prevents water hammer effects by gradually reducing flow rather than abrupt simultaneous closure, thereby minimizing harmful pressure surges and potential damage to the valve system.

Inventive Principle:

Principle #10Preliminary action

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 configuration reduces the operational stress on the secondary valve, allowing it to close more gently and effectively, thereby maintaining well control and reducing the risk of further damage, while enabling efficient and cost-effective maintenance by delaying the closure of the secondary valve until the primary valve has already reduced flow significantly.

Implementation Method 1

a choke in fluid communication with the second control line port to delay a closing of the second flapper relative to a closing of the first flapper in response to a decrease in the control fluid pressure

Methodology Applied

Scientific EffectFluid flow restriction through choke: Pressure Drop

Implementation Method 2

Hydraulic fluid pressure must be applied to the TRSV to place the TRSV in the open position

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentUS11661826B2Well flow control using delayed secondary safety valve

Publication Date: 2023.05.30 HALLIBURTON ENERGY SERVICES INC

AI summary

A flow control system for a well includes a primary safety valve and a secondary safety valve disposable within a valve body of the primary safety valve. The secondary safety valve may include a control line port for receiving control fluid pressure from the same control line as the primary safety valve. A choke in fluid communication with the control line port delays a closing of the secondary safety valve relative to a closing of the primary safety valve in response to a decrease in the control fluid pressure.