Tie Back Receptacle Seal Assembly Tapered Geometry
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Solution Overview
Problem
Current tie back assemblies in subterranean wells have a relatively low pressure rating, limiting their use in deep water wells and not meeting new regulatory requirements, as they typically have a pressure rating about half that of the liner pressure rating due to geometric limitations.
Innovation Solution
A tie back assembly with a tie back seal and receptacle system featuring tapered surfaces for the seal mandrel and receptacle, including burst and collapse seals spaced apart for increased wall thickness, and additional features like cooperating grooves and ridges for enhanced friction and sealing, allowing for higher pressure ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional tie back assemblies are used with standard geometric design, then the assembly is simple to manufacture and install, but the pressure rating is limited to about half the liner pressure rating
Solution Approach 1:
The patent transitions from traditional cylindrical tie back assemblies to a conical geometry, utilizing the radial dimension to achieve higher pressure ratings. The conical shape allows the assembly to withstand greater differential pressures by distributing stresses more effectively across the structure, thereby achieving pressure ratings equal to or greater than the liner pressure rating without proportionally increasing complexity.
Solution Approach 2:
The invention changes the geometric parameters of the tie back assembly by employing a conical configuration with specific angle ranges (typically 15-45 degrees). This parameter change fundamentally alters the mechanical properties and pressure承受能力 of the assembly, enabling it to achieve higher pressure ratings while maintaining reasonable structural simplicity.
2Strength
If the wall thickness is increased to support higher pressures, then the pressure rating improves, but the friction between mandrel and receptacle decreases under high hydrostatic pressure
Solution Approach 1:
The patent employs conical surfaces with optimized angles to maintain sufficient friction forces between the mandrel and receptacle even under high hydrostatic pressures. The curved conical geometry creates favorable contact conditions that preserve frictional engagement, preventing slippage while supporting the increased pressure loads through the thicker wall design.
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
The solution provides a tie back assembly with significantly increased pressure ratings, enabling its use in deep water wells and compliance with new regulations by maintaining a secure seal and increased friction between the mandrel and receptacle, even under high hydrostatic pressure.
Implementation Method 1
A seal assembly forms an annular seal between the tapered surfaces when the mandrel is inserted into the receptacle
Implementation Method 2
Hydrostatic fluid in the wellbore preferably assists in maintaining the seal mandrel and receptacle in position
Data Source
AI summary
A tie back assembly and method of use is presented. In one method, a tie back seal mandrel is inserted into a tie back receptacle. Both the inner surface of the tie back receptacle and the outer surface of the seal mandrel are tapered to cooperate when mated. A seal assembly forms an annular seal between the tapered surfaces when the mandrel is inserted into the receptacle. Preferably the seal assembly has a burst seal and a collapse seal carried on one of the tapered surfaces, where the seals are spaced apart longitudinally. The seals are positioned at locations along the tapered surfaces to provide adequate wall thickness for support at pressure. Hydrostatic fluid in the wellbore increases the force necessary to withdraw the seal mandrel dues to creation of a lower pressure zone between the spaced apart seals.