Casing Ram Swivel for High Differential Pressure Frac Packs
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Solution Overview
Problem
Existing swivels and tools designed for annular blowout preventers face limitations in handling high differential pressures during frac pack operations, which restrict aggressive treatments and ultimate recovery, as they are limited by the pressure rating of the annular BOP, typically not exceeding 5,500 psi, and complicate precise tool movement due to friction.
Innovation Solution
A swivel designed to fit within a casing ram, featuring a slick inner mandrel sealed inside an outer housing, allowing rotation and reciprocation with reduced friction, and capable of operating at differential pressures up to 10,000 psi or more, facilitating aggressive frac pack treatments and efficient reverse out operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular BOP is used to seal on the workstring, then the workstring can be sealed and circulated under pressure, but the friction between the annular seal and workstring creates high axial loads that complicate rotating and reciprocating the workstring
Solution Approach 1:
The device divides the sealing system into two separate components: an outer housing that seals with the casing ram (fixed seal) and an inner mandrel that rotates and reciprocates freely (moving seal). This segmentation allows the stationary seal to handle high pressure while the moving components experience minimal friction.
Solution Approach 2:
The outer housing acts as an intermediary between the annular BOP seal and the inner mandrel. The annular BOP seals on the outer housing instead of directly on the workstring, reducing friction on the rotating inner mandrel while maintaining sealing capability.
2Productivity
If the annular BOP pressure rating is exceeded, then aggressive frac pack treatments can be performed, but the annular BOP cannot withstand pressures above its rating (typically 5,500 psi)
Solution Approach 1:
The sealing function is segmented between the outer housing (sealed by annular BOP) and the inner mandrel (sealed by casing rams). This allows the system to utilize the higher pressure rating of the casing rams (10,000+ psi) for the inner mandrel seal while the outer housing handles the annular BOP seal at lower pressures.
Solution Approach 2:
The device creates a secondary sealing system using the casing rams that replicates the sealing function of the annular BOP but at higher pressure ratings. The inner mandrel seal provides a backup and enhancement to the primary annular BOP seal.
3Ease of operation
If a slick inner mandrel is sealed inside the outer housing, then friction is reduced allowing rotation and reciprocation, but the annular BOP pressure rating limit remains unchanged
Solution Approach 1:
The device segments the pressure-containing functions: the outer housing contains the annular BOP seal at lower pressures, while the inner mandrel contains the workstring fluid at higher pressures. This segmentation allows the inner mandrel to rotate freely while the outer housing maintains the annular BOP seal integrity.
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 swivel enables higher differential pressure operations, allowing for more aggressive frac pack treatments and efficient reverse out operations, maximizing production rate and ultimate recovery by exceeding the pressure rating limitations of traditional annular BOPs.
Implementation Method 1
The friction between the annular seal and the workstring creates high axial loads that complicate rotating and reciprocating the workstring
Implementation Method 2
The outer housing is positioned and sealed in an annular BOP. Thus, the tool is static while allowing the inner mandrel to rotate and reciprocate with minimal friction even at high pressure differential
Implementation Method 3
allowing for differential pressure during operation as high as 10,000 pounds per square inch (psi) or more
Data Source
AI summary
The present application pertains to a swivel insertable into a casing ram. The swivel comprises an inner mandrel having an upper end section and a lower end section configured to be operably connectable and rotatable with an upper workstring section and a lower workstring section, the inner mandrel comprising a longitudinal passage forming a continuation of a passage in the workstring. An outer housing is configured to seal the inner mandrel inside the outer housing. The outer diameter of the outer housing and the length of the outer housing is configured to fit a casing ram. In contrast to prior art tools placed within annular blowout preventers which have limited differential pressure ranges, the instant device allows for differential pressure during operation as high as 10,000 psi or more. The instant devices also may allow for aggressive frac pack treatments and facilitate reverse out operations.