TRSV Secondary Flapper Assembly for Emergency Flow Shut-Off
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Solution Overview
Problem
Existing tubing retrievable safety valves (TRSVs) face issues such as failure, leakage, and improper opening/closing, necessitating a secondary means for blocking fluid flow that avoids the complications and limitations of wireline retrievable safety valves (WRSVs, which are cumbersome to install, restrict flow, and have limited setting depth.
Innovation Solution
A TRSV assembly with a primary flapper, secondary flapper, flow tube, and protective sleeve, where the flow tube shifts to control the primary flapper's position and the protective sleeve controls the secondary flapper's position, allowing seamless transition without additional tools or line modifications, maintaining flow diameter and depth functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a WRSV is installed inside an existing TRSV, then a secondary safety function is provided, but the installation process becomes complicated and time-consuming requiring multiple trips with wireline service tools
Solution Approach 1:
The patent applies nesting by placing the secondary safety valve assembly inside the existing TRSV. The WRSV is lowered via wireline and positioned within the TRSV body, where it nests against the flow tube and control line. This nested configuration provides the secondary safety function while requiring minimal installation complexity and time.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the WRSV with all necessary components (flow tube, control line, valve mechanism) before deployment. The WRSV is prepared in advance as a complete assembly that can be quickly deployed via wireline and immediately functional upon installation, eliminating the need for complex on-site assembly procedures.
2Reliability
If a WRSV is installed inside an existing TRSV, then a secondary safety function is provided, but drilling a hole through the flow tube creates potential leakage issues
Solution Approach 1:
The patent applies the intermediary principle by introducing a seal element that mediates between the WRSV control line and the TRSV internal hydraulic system. This seal creates a controlled communication path for hydraulic fluid while preventing uncontrolled leakage. The intermediary seal ensures that hydraulic pressure is transmitted reliably to actuate the WRSV without compromising system integrity.
3Reliability
If a WRSV is installed inside an existing TRSV, then a secondary safety function is provided, but the flow path is restricted due to smaller flow diameter
Solution Approach 1:
The patent applies local quality by designing the WRSV flow path to optimize flow characteristics at each stage. The flow tube is configured with appropriate diameter and length to minimize pressure loss, and the flow path geometry is optimized to reduce turbulence and restriction. This localized optimization of flow properties allows the compact WRSV to maintain adequate flow capacity despite its smaller size compared to the TRSV.
4Length of stationary object
If a WRSV is installed at increased setting depth, then deeper well coverage is achieved, but formation pressure increases making it difficult for the control mechanism to maintain closed position
Solution Approach 1:
The patent applies hydraulics by using hydraulic pressure transmitted through the control line to actuate the WRSV. The hydraulic system is designed to generate sufficient force to overcome the increased formation pressure at greater depths. The hydraulic fluid transmits force efficiently from the surface control system to the deep-set WRSV, enabling reliable operation despite the challenging pressure environment.
Solution Approach 2:
The patent applies parameter changes by adjusting the control mechanism parameters (spring force, hydraulic pressure, valve geometry) to compensate for increased formation pressure at greater depths. The system can modify its operational parameters dynamically to maintain the closed position against higher forces, allowing the WRSV to function effectively at increased setting depths.
Data Source
AI summary
A tubing retrievable safety valve assembly and related methods are disclosed herein. The assembly includes a primary flapper, a secondary flapper, a flow tube, and a protective sleeve. The flow tube is shiftable between a downhole position that holds the primary flapper in an open position and an uphole position that allows the primary flapper to move to a closed position. The protective sleeve, when positioned in an uphole position, holds the secondary flapper valve in an open position. The protective sleeve is shiftable to a downhole position to allow the secondary flapper to move to a closed position, for example, upon failure of the primary flapper.