Casing Hanger Assembly Relocated to Cellar Floor
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Solution Overview
Problem
Existing casing hangers cause shifting and cracking of cement in well casings due to weight and vibrations during drilling, leading to well fluid migration and contamination of soil and groundwater.
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
1Force
If existing casing hangers are used to suspend the weight of inner casing on outer casing, then the casing weight is supported, but the cement cracks and shifts due to concentrated weight and vibrations
Solution Approach 1:
The casing hanger is extracted from the wellhead assembly and repositioned to the cellar floor, separating the weight-bearing function from the wellhead components. This allows the cement to remain intact while still supporting the casing weight through the cellar floor distribution
Solution Approach 2:
The weight distribution is transitioned from a point-contact support (existing hanger on casing) to a surface-area support (cellar floor). The hanger distributes weight over the first area of the cellar floor, changing the dimensional approach from linear to areal distribution
2Ease of operation
If weight is supported by partially cured cement, then the wellhead assembly can be attached, but the cement cracks and containment is broken
Solution Approach 1:
The casing hanger function is extracted from the wellhead assembly and relocated to the cellar floor, eliminating the need for partially cured cement to bear the wellhead assembly weight. This separates the wellhead installation process from the cement curing requirement
Solution Approach 2:
The cellar floor acts as an intermediary structure between the casing weight and the ground, providing a stable support surface that does not rely on cement curing. This intermediary allows wellhead assembly installation without compromising containment integrity
3Stability of the object's composition
If casing hanger is secured to the cellar floor distributing weight over a larger area, then cement integrity is maintained, but the device complexity increases
Solution Approach 1:
The hanger assembly is segmented into distinct functional components: the hanger body that engages the casing, the weight distribution interface with the cellar floor, and the wellhead assembly interface. This modular segmentation allows each component to perform its specific function while maintaining overall 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. Optionally, a lock down mechanism can be used to prevent buoyancy and hydraulic forces from causing the well to pack off.