Offset Cementing Tool for Horizontal Wellbore Coverage
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Solution Overview
Problem
Existing cementing techniques often result in channeling issues during well abandonment, especially in horizontal, deviated, and large holes, due to inadequate borehole coverage and irregular hole shapes, leading to potential gas migration and contamination risks.
Innovation Solution
A secondary cementing apparatus with a drill string and a tool having an offset distal portion from the central axis, allowing selective rotation and fluid flow through strategically positioned ports to ensure comprehensive cement distribution and plug formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard cementing tool aligned with the drill string axis is used, then the device complexity is low and ease of operation is high, but the cement coverage is inadequate leading to channeling in horizontal, deviated, and large holes
Solution Approach 1:
The cementing tool employs an asymmetric configuration where the distal portion is offset from the central axis of the drill string. This asymmetric positioning allows the tool to reach irregular regions of the borehole, particularly in horizontal and deviated wells, ensuring comprehensive cement coverage that symmetric tools cannot achieve.
Solution Approach 2:
The invention transitions from a one-dimensional axial alignment to a two-dimensional offset positioning. By positioning the distal portion at an offset distance from the drill string axis, the tool creates a radial dimension of coverage that enables cement to reach all regions of the borehole, including irregular shapes and large diameters, thereby eliminating channeling.
2Reliability
If the drill string diameter is much smaller than the hole diameter in large holes, then the tool can be simpler, but the tool cannot direct cement to the outer edges of the borehole
Solution Approach 1:
The offset distal portion creates an asymmetric cement delivery system that extends the reach of cement to the outer edges of large boreholes. This asymmetric configuration compensates for the size discrepancy between the drill string and the hole, ensuring cement reaches all regions including the far walls of large diameter holes.
3Reliability
If the drill string is not centered in the hole, then the tool structure remains simple, but it becomes difficult to completely fill the upper region or high side of the hole
Solution Approach 1:
The offset distal portion is specifically designed to address off-center drill string conditions. By positioning the cement delivery point away from the axis, the tool can reach the high side and upper regions of the hole even when the drill string is not centered, ensuring complete coverage without requiring complex active positioning systems.
4Reliability
If conventional cementing is used in horizontal and deviated holes, then the process is simpler and faster, but channeling occurs due to inadequate coverage
Solution Approach 1:
The asymmetric offset configuration provides reliable plug integrity in horizontal and deviated wells by ensuring complete borehole coverage, while maintaining operational simplicity that preserves cementing efficiency. The fixed geometric offset requires no complex control systems or additional operational steps.
Solution Approach 2:
By adding a radial dimension to cement delivery through the offset distal portion, the tool achieves comprehensive coverage in horizontal and deviated holes without compromising productivity. The geometric design inherently directs cement to all regions including the high side and outer edges, eliminating channeling while maintaining efficient operation.
Data Source
AI summary
A secondary cementing apparatus includes a drill string, a coupling coupled to a distal end of the drill string, and a tool coupled to a distal end of the coupling, the tool having a distal portion offset from a central axis of the drill string, and the coupling configured to allow selective rotation of the tool with respect to the drill string. A method for plugging a hole includes rotating a drill string about a central axis of the drill string, wherein a distal end of the drill string is coupled to a tool, the tool having an offset distal portion from a central axis of the drill string; and flowing a fluid down the drill string and out of the offset distal portion of the tool as the drill string is rotated.