PDC-Roller Hybrid Drill Bit With Composite Sealing
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Solution Overview
Problem
PDC bits exhibit low penetration rate and short service life in medium-to-hard formations, while roller bits have instability and tooth breakage issues, particularly in heterogeneous formations, and PDC-roller hybrid bits suffer from seal failure.
Innovation Solution
A PDC-roller hybrid drill bit design incorporating a roller assembly with a rolling wheel and PDC assembly, featuring a sealing assembly with polished seals and elastic support members, lubrication system, and structured oil passages to enhance penetration, stability, and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PDC bits are used in medium-to-hard formations, then cutting efficiency is improved, but service life is reduced due to low penetration rate and insufficient durability
Solution Approach 1:
The patent combines PDC cutters and roller cones into a hybrid drill bit structure. The PDC assembly provides high cutting efficiency for medium-to-hard formations, while the roller assembly with conical body provides stability and durability. This merging allows the drill bit to achieve both high penetration rate and extended service life by leveraging the strengths of both PDC and roller cone technologies.
2Stability of the object's composition
If roller bits are used for orientation in directional wells, then tool face stability is improved, but penetration rate is reduced due to tooth breakage and low drilling footage
Solution Approach 1:
The hybrid drill bit merges the stabilizing function of roller cones with the high-efficiency cutting function of PDC cutters. The roller assembly provides tool face stability and orientation control in directional wells, while the PDC assembly maintains high penetration rate by preventing tooth breakage through the protective structure and material properties of PDC cutters.
3Productivity
If PDC-roller hybrid bits are used to increase drilling rate, then penetration efficiency is improved, but seal failure occurs after long-term use reducing service life
Solution Approach 1:
The patent incorporates a lubrication system with oil passages and lubricating holes that provide beforehand cushioning to the sealing assembly. The lubrication system reduces friction and wear on the roller shaft and sealing components before failure can occur, allowing the seal to withstand long-term use and maintain durability while the drill bit operates at high drilling rates.
4Device complexity
If roller shaft is rotatably connected to rolling wheel without lubrication, then structural simplicity is maintained, but friction and wear increase reducing service life
Solution Approach 1:
The patent introduces a lubrication system using hydraulic principles, where lubricating oil is delivered through oil passages and lubricating holes to the roller shaft and rolling wheel interface. This hydraulic lubrication approach maintains relative structural simplicity while dramatically reducing friction and wear, thereby extending service life without requiring complex mechanical lubrication mechanisms.
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 high penetration rates, improved tool-face stability, extended service life, and reduced drilling costs by combining the advantages of both PDC and roller bits, with enhanced sealing and lubrication systems.
Implementation Method 1
an oil passage is arranged in the roller arm, wherein the oil passage is configured such that oil in the oil cavity flows to contact surfaces between the roller shaft and the rolling wheel
Implementation Method 2
at least one axial end of the sealing assembly is provided with a first support member with elasticity, which is configured to exert axial pressure on the first seal and the second seal
Data Source
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AI summary
The present invention relates to the technical field of drilling tool for petroleum and geological engineering. Specifically, the present invention relates to a PDC-roller hybrid drill bit, comprising: a bit body; a roller assembly arranged in a roller area, comprising a roller arm fixedly connected to the bit body, a roller shaft fixedly connected to the roller arm, a rolling wheel on the roller shaft, and at least one roller tooth arranged along a circumferential direction of the rolling wheel; and an oil cavity and an oil passage arranged in the roller arm, wherein the oil passage is configured such that oil in the oil cavity flows to contact surfaces between the roller shaft and the rolling wheel, and sealing assemblies for sealing the rolling wheel are arranged at both ends of the roller shaft and comprise a composite sealing ring. In the present invention, the service life of the hybrid drill bit can be greatly extended, and the drilling footage, rate of penetration and directional performance thereof in heterogeneous formations can be significantly improved, thus facilitating the acceleration of exploration and development of oil/gas and mine fields as well as the cost reduction thereof.