Double Shoulder Tool Joint Guard Portion Sealing
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Solution Overview
Problem
Double shoulder tool joints used in deepwater and horizontal well drilling face challenges in maintaining liquid sealability due to surface roughness damage and inadequate sealing when subjected to repeated make-up and break-out operations, leading to potential leakage issues.
Innovation Solution
The design incorporates guard portions with specific contact surfaces and dimensions on the box and pin, including a pin nose and box sealing surfaces, to enhance sealing performance and resist damage, ensuring excellent liquid sealability by configuring the contact surfaces to receive pressure and maintain surface roughness within optimal limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the tool joint shoulder is used as a pressure-receiving surface for tightening torque, then torque transmission is improved, but the surface roughness deteriorates due to repeated make-up and break-out operations, compromising liquid sealability
Solution Approach 1:
The tool joint is segmented into multiple contact surfaces: the first contact surface (box access sleeve end surface) receives axial pressure first, while the second contact surface (internal shoulder) and fourth contact surface (pin sealing surface) are positioned to receive pressure subsequently. This segmentation separates the primary load-bearing function from the sealing function, allowing the sealing surfaces to be protected from direct repeated contact damage while still enabling effective torque transmission through the threaded portions.
Solution Approach 2:
The guard portion with the fifth contact surface is positioned to contact the external shoulder end surface before the main sealing surfaces engage. This preliminary contact action protects the subsequent sealing surfaces (second and fourth contact surfaces) from direct impact and damage during make-up operations, ensuring they maintain their surface roughness and sealing capability for longer operational life.
2Force
If the pin nose tip is positioned to contact the internal shoulder for torque resistance, then torque performance is improved, but the pin nose tip becomes susceptible to damage when the tool joint is stood on the floor of a rig, compromising liquid sealability
Solution Approach 1:
The guard portion with the sixth contact surface is positioned to contact the internal shoulder end surface before the pin sealing surface (fourth contact surface) engages with the box sealing surface (second contact surface). This preliminary contact protects the pin sealing surface from direct impact damage when the tool joint is stood on the floor, while still allowing the pin nose to provide adequate torque resistance through the threaded engagement.
Solution Approach 2:
The guard portion acts as an intermediary protective element between the external environment (floor contact) and the critical pin sealing surface. By positioning the guard portion's sixth contact surface to engage first with the internal shoulder, it absorbs impact forces and prevents direct damage to the pin nose tip, thereby maintaining the sealing surface integrity and liquid sealability.
3Force
If the contact surface area between the tip of the box access sleeve and the external shoulder is increased, then torque resistance performance is improved, but the complexity of maintaining surface roughness and liquid sealability increases
Solution Approach 1:
The contact surfaces are segmented into distinct functional zones: the first contact surface (box access sleeve end surface) and third contact surface (external shoulder end surface) provide the primary large-area contact for torque resistance, while the second and fourth contact surfaces are positioned as secondary sealing surfaces that engage subsequently. This segmentation allows the primary contact surfaces to be optimized for torque resistance without compromising the sealing surfaces, as they engage at different stages and have different functional requirements.
Data Source
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AI summary
A double shoulder tool joint, whose a sealing surface (including a pin sealing surface and a box sealing surface) is less subject to damages so that the tool joint has excellent liquid sealability when the drill pipes are interlocked and used, is provided. A double shoulder tool joint includes a box having a box access sleeve including a first contact surface perpendicular to a pipe axis, a female threaded portion having a taper relative to the pipe axis, a box backward sleeve including a second contact surface perpendicular to the pipe axis, and a pin having a pin base including a third contact surface to contact the first contact surface, a male threaded portion to be screwed and engaged to the female threaded portion, a pin nose including a fourth contact surface perpendicular to the pipe axis to contact the second contact surface. The double shoulder tool joint further includes a guard portion including a fifth contact surface provided in a tip portion of the box extended forward from the first contact surface or a sixth contact surface provided in a tip portion of the pin extended forward from the fourth contact surface.