Downhole Slip Segments with Axial Inserts for Casing Grip
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Solution Overview
Problem
Downhole tools face challenges in maintaining a strong grip on well casings under high differential pressures, as existing slip segments often fail to provide sufficient sealing and anchoring, leading to potential movement during operations.
Innovation Solution
The design incorporates an expandable packer element with radially movable slip rings and cylindrically shaped inserts oriented in parallel cavities, which engage the well casing to enhance gripping ability and prevent premature movement, utilizing drillable materials like phenolic and tungsten carbide buttons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If buttons are made harder to penetrate the casing surface, then gripping ability is improved, but resistance to drilling and milling deteriorates
Solution Approach 1:
The patent changes the orientation parameter of the buttons from radial (perpendicular to casing) to axial (parallel to casing). This parameter change allows the buttons to maintain sufficient hardness for gripping while reducing their ability to resist drilling, as the cutting surfaces can now ride over the axially oriented buttons rather than encountering perpendicular resistance.
Solution Approach 2:
The slip segments are made from composite materials that combine drillable materials (such as phenolic resin or other thermosetting plastics) with hard buttons (such as tungsten carbide or other hard metals). This composite construction allows the slip segment body to be easily drilled while the buttons provide the necessary gripping hardness.
2Ease of manufacture
If slip segments are made from drillable materials, then ease of removal is improved, but gripping ability deteriorates
Solution Approach 1:
The slip segments use composite materials where the matrix material (phenolic resin or other thermosetting plastics) provides drillability while embedded hard buttons (tungsten carbide or other hard metals) provide gripping ability. This allows the slip segments to be easily drilled for removal while the buttons maintain sufficient hardness to grip the casing.
Solution Approach 2:
The slip segments are divided into functional components: the slip segment body made from drillable material and the separate buttons made from hard material. This segmentation allows each component to be optimized for its specific function - the body for drillability and the buttons for gripping.
3Strength
If buttons are oriented radially to maximize biting into casing, then gripping ability is improved, but drilling and milling becomes more difficult
Solution Approach 1:
The patent inverts the conventional radial orientation of buttons to an axial orientation parallel to the casing. This inversion changes the interaction mechanism from biting (radial penetration) to rubbing/riding (axial contact), which reduces drilling resistance while maintaining gripping ability through friction and mechanical interlocking.
Data Source
AI summary
A downhole tool has a mandrel with slip assemblies positioned thereon above and below a packer element. The slip assemblies are positioned in a manner to anchor the downhole tool in the well. The slip assemblies include a slip ring which has a plurality of slip segments. Each slip segment has inserts disposed in cavities therein. The cavities are oriented such that the longitudinal central axis of each cavity is parallel to the longitudinal central axis of each of the other cavities in the slip segment.