Variable-Grade Expansion Tool for Deep-Strata Drilling Sealing
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Solution Overview
Problem
Deep-strata drilling in petroleum and natural gas exploration faces challenges such as large pressure gradients, high temperatures, and frequent leakage due to the rough surface of formations, leading to issues with conventional sealing methods and expansion pipe damage.
Innovation Solution
A hydraulic variable-grade expansion tool is designed with a conversion joint, supporting central pipe, pressure gradient piston subs, and O-rings to achieve low pressure, large expansion force, and reliable sealing, avoiding drilling out bottom sealing joints and reducing expansion failure risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional expansion method is used, then expansion force is large, but internal pressure in tubular string is relatively large causing damage to ground equipment and tubular string
Solution Approach 1:
The expansion tool is divided into multiple independent expansion cones (first expansion cone, second expansion cone, etc.) that can expand at different pressure levels. Each expansion cone operates independently to expand the expansion pipe in stages, allowing the system to achieve large expansion force while controlling internal pressure to prevent equipment damage.
Solution Approach 2:
The patent employs a dynamic expansion process where the expansion cones are activated sequentially rather than simultaneously. The first expansion cone expands at a lower pressure, then the second expansion cone expands at a higher pressure, creating a dynamic pressure gradient that optimizes both expansion force and pressure control throughout the operation.
2Force
If expansion pipe with large wall thickness is used, then expansion force is large, but diameter-thickness ratio is small making conventional seal ineffective
Solution Approach 1:
Different expansion cones are designed with different structural characteristics suited to their specific expansion stages. The first expansion cone has structural features optimized for low-pressure expansion, while the second expansion cone has features optimized for high-pressure expansion. This local optimization ensures reliable sealing at each stage despite the varying wall thickness requirements.
Solution Approach 2:
The patent changes key parameters between different expansion cones, including wall thickness, diameter, and structural configuration. The first expansion cone uses parameters suitable for initial expansion, while the second expansion cone uses different parameters optimized for final expansion, allowing effective sealing across the full range of pressure and thickness conditions.
3Device complexity
If single-stage expansion is used, then construction process is simple, but pressure is too high causing equipment damage
Solution Approach 1:
The expansion process is segmented into multiple stages with each stage handled by a dedicated expansion cone. This segmentation breaks down the high-pressure operation into manageable steps, where each cone operates at appropriate pressure levels, simplifying the overall construction process while avoiding excessive pressure that would damage equipment.
4Reliability
If expansion pipe is used for open-hole plugging, then leakage is reduced, but rough surface and out-of-roundness increase causing expansion failure
Solution Approach 1:
The dynamic, multi-stage expansion process allows the expansion pipe to adapt to rough and out-of-round hole conditions. By expanding in stages with each cone making incremental adjustments, the system can compensate for surface irregularities and achieve proper sealing without requiring high manufacturing precision of the hole.
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 tool automatically controls well-head pressure to ensure low pressure, large expansion force, and reliable sealing, reducing the risk of expansion failure and equipment damage during deep-strata drilling.
Implementation Method 1
pressuring drilling fluid by a pressure pump on the ground, enabling the drilling fluid to reach inner holes of the supporting central pipe (2) and the double male thread central shafts (9) through an inner hole of the tubing string, and enter each of pressure chambers which includes a first pressure chamber (22), a second pressure chamber (25), a third pressure chamber (26) and a fourth pressure chamber (27) through circumferential holes of a corresponding one of the double male thread central shafts (9), enabling the drilling fluid which with high pressure to push each of the pressure gradient piston subs (5) to move upward axially, and driving the expansion cone (11) to expand the expansion pipe (4)
Implementation Method 2
When moving the pressure gradient piston subs (5) upwards for one stroke, pushing the upper sealing ball (18) up by the tapered guide sub (19), driving the T-shaped ball compressor (13) by the sealing ball (18) to compress the reciprocating spring (16), enabling high pressure fluid in the variable-grade expansion tool to flow out through the inner hole of the tapered guide sub (19), and enabling the internal pressure of the variable-grade expansion tool to decrease sharply
Data Source
AI summary
A patching construction method using a hydraulic variable-grade expansion tool for blocking during drilling is provided, which includes a conversion joint, a supporting central pipe, a supporting ring, an expansion pipe, pressure gradient piston subs, double female thread connection subs, T-shaped limiting subs, a tapered centering sub, double male thread central shafts, split supporting subs, an expansion cone, a piston sub with male and female threads, a T-shaped ball compressor, a lower U-shaped pressing sleeve, a ball-seat fixing sleeve, a reciprocating spring, a sealing ball seat, a sealing ball, a tapered guide sub, etc. A patching construction method using a hydraulic variable-grade expansion tool for blocking during drilling, omits the conventional expansion cone sealing manner, and designs a variable pressure gradient expansion tool, so that achieves the objectives of low pressure, large expansion force and reliable sealing, avoids drilling out bottom sealing joint, and reduces the risk of expansion failure.