Ball Seat with Segmented Sealing Element for Multistage Stimulation
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Solution Overview
Problem
Current ball seats used in multistage oil and gas well stimulation face challenges in hermeticity and anchoring, leading to leakage and unreliable anchoring forces due to material limitations and complex assembly processes.
Innovation Solution
A ball seat design featuring a cone frustum mandrel with a two-segment sealing element and multi-layered frictional slips, where the first segment expands easily for initial sealing and the second segment enhances pressure-bearing capabilities, combined with a baffle ring and dissolvable materials for enhanced sealing and anchoring, ensuring persistent hermeticity and reduced residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sealing element is used in the ball seat, then the structure is simple, but the hermeticity is insufficient under high pressure conditions
Solution Approach 1:
The sealing element is divided into two segments with different hardness values. The first segment has lower hardness for easy expansion and initial sealing, while the second segment has higher hardness for pressure bearing. This segmentation resolves the contradiction by providing both hermeticity and structural simplicity through functional division.
Solution Approach 2:
Different regions of the sealing element are assigned different hardness properties to fulfill different functions. The first segment (lower hardness) is optimized for expansion and sealing contact, while the second segment (higher hardness) is optimized for withstanding pressure. This local quality differentiation achieves high hermeticity without requiring a completely complex multi-component structure.
2Productivity
If conventional plugs are used for zonal isolation, then the well can be fully accessed, but drilling out is time-consuming
Solution Approach 1:
The ball seat uses a dissolvable material that can be degraded by acid or other chemicals after serving its isolation function. This disposable approach eliminates the need for time-consuming drilling out operations, significantly improving productivity while the large inner diameter maintains ease of wellbore re-entry for refrac operations.
3Ease of manufacture
If the sealing element is made of soft material for easy expansion, then initial sealing is easy to form, but pressure-bearing capability is reduced
Solution Approach 1:
The sealing element is segmented into two distinct hardness zones. The first segment uses softer material that easily expands to form initial sealing contact with the casing wall, while the second segment uses harder material that provides the necessary pressure-bearing capability to maintain sealing under high pressure conditions.
Solution Approach 2:
The sealing element exhibits local quality variation in hardness across its structure. The region contacting the casing wall has lower hardness for easy deformation and sealing formation, while the region facing the pressure load has higher hardness for strength. This local differentiation resolves the contradiction between ease of sealing formation and pressure-bearing capability.
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 design achieves improved hermeticity and anchoring by synchronizing sealing and anchoring processes, reducing leakage and operational complexity, while minimizing residue and simplifying post-operation milling.
Implementation Method 1
the hardness of the first segment of the sealing element is low, and the first segment of the sealing element is situated at the end of the mandrel with larger external diameter, such sealing element tends to expand, and the initial sealing can be easily to be formed
Implementation Method 2
the hardness of the second segment of the sealing element is higher, and the flexibility of the rubber sleeve is reduced, the pressure-bearing effect of the sealing element is enhanced, and thus, the hermeticity can be warranted
Implementation Method 3
multi-layered frictional slips
Data Source
AI summary
A ball seat configured for multistage stimulation in oil and gas wells includes bottom sub, slips, sealing element and mandrel. The mandrel is a cone frustum, and it's exterior is encased by the sealing element and slips. One end of the sealing element is attached to one end of slip, the end of the cone frustum mandrel with the smallest exterior diameter is completely encased by slips. One end of the bottom sub is attached the other end of the slip. The bottom sub includes a threaded shearing connecting structure, which is designed to connect the setting tool adaptor used to deploy the ball seat into the oil or gas well. The sealing element is a two-segment structure, the hardness of the first segment is lower than that of the second segment.