Cellar-Mounted Casing Hanger Assembly for Cement Integrity
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Solution Overview
Problem
Existing casing hanger systems cause shifting and cracking of cement in well casings due to weight and vibrations, leading to well fluid migration and contamination of soil and groundwater during drilling operations.
Innovation Solution
A casing hanger assembly that is not part of the wellhead assembly, secured to the floor of a containment well cellar, distributing the weight of the casings and drilling forces over a larger area, preventing cement shifting and ensuring cement integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing casing hangers are used to suspend the weight of inner casing on outer casing, then the casing can be supported, but the weight and vibrations cause shifting of well casings and cracking of cement
Solution Approach 1:
The invention extracts the casing support function from the wellhead assembly and relocates it to a cellar floor-mounted hanger system. The hanger is separated from the wellhead assembly and independently mounted to the cellar floor, thereby removing the source of vibrations and weight concentration that caused cement cracking while maintaining casing support capability
Solution Approach 2:
The invention transitions from a point-supported hanger system (concentrated load on outer casing) to a area-supported system (distributed load on cellar floor). The hanger distributes weight over a larger surface area of the cellar floor, converting a concentrated force into a distributed load, which prevents cement cracking
2Ease of manufacture
If weight of BOP and wellhead assembly is supported by partially cured cement, then the equipment can be installed, but the cement cracks and containment is broken
Solution Approach 1:
The invention introduces the cellar floor as an intermediary support structure between the wellhead assembly and the ground. The hanger system transfers equipment weight through the cellar floor rather than directly through the cement, preventing cement cracking while maintaining installation capability
Solution Approach 2:
The invention segments the support system into separate functional components: the cellar floor provides structural support, the hanger provides casing suspension, and the cement provides only sealing function. This segmentation allows each component to perform its optimal function without interfering with others
3Device complexity
If casing hanger is integrated into wellhead assembly, then the assembly is compact, but the concentrated weight causes shifting and contamination
Solution Approach 1:
The invention extracts the hanger from the wellhead assembly and relocates it to the cellar floor mounting system. This separation eliminates the harmful concentrated loads and vibrations that caused cement failure and subsequent contamination, while the cellar floor provides a stable foundation
4Ease of operation
If cement is used to support heavy equipment, then installation is simplified, but cement cracking allows well fluid migration
Solution Approach 1:
The invention introduces the cellar floor as an intermediary bearing surface that takes over the load-bearing function from the cement. The cement is relieved of structural support duties and retains only its sealing function, ensuring containment integrity while maintaining installation simplicity
Data Source
AI summary
A casing hanger assembly includes a landing ring secured to a containment well cellar or the conductor pipe. A casing hanger welded to the external surface of the last section of surface casing seats into the landing ring.