Rotating Continuous Flow Sub for Drilling Fluid Circulation
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Solution Overview
Problem
Drilling operations are disrupted when adding or removing drill string sections, leading to cessation of drilling fluid circulation, which can cause formation damage, overpressuring, and increased costs due to the need for re-starting mud circulation and maintaining specific mud weights.
Innovation Solution
A rotating continuous flow sub (RCFS) system that allows for continuous drilling fluid circulation by injecting fluid into a side port while adding or removing drill string sections, using a tubular housing with radial flow ports, a swivel, and a closure member to maintain fluid flow and prevent leaks, enabling rotation and longitudinal movement of the drill string without stopping fluid injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If drilling fluid circulation is stopped when adding or removing drill string sections, then the drill string can be assembled or disassembled, but the formation may become damaged and overpressured, and drilling efficiency decreases
Solution Approach 1:
The patent maintains continuous drilling fluid circulation through the drill string during assembly and disassembly operations by using a valve assembly that allows fluid to bypass the connection point. The valve body with bypass passage enables fluid to flow continuously through the drill string even when sections are being added or removed, eliminating the need to stop circulation and maintaining drilling efficiency.
2Ease of manufacture
If drilling fluid circulation is stopped when adding or removing drill string sections, then the drill string can be assembled or disassembled, but formation damage and overpressuring occur
Solution Approach 1:
The valve assembly with bypass passage maintains continuous drilling fluid circulation through the drill string during assembly operations, preventing formation damage by ensuring constant fluid flow that keeps cuttings suspended and maintains wellbore pressure balance.
Solution Approach 2:
The bypass passage acts as an intermediary flow path that allows drilling fluid to circumvent the connection point where sections are being assembled or disassembled. This intermediary channel ensures continuous fluid circulation is maintained even when the main drill string pathway is interrupted for maintenance operations.
3Ease of manufacture
If drilling fluid circulation is stopped when adding or removing drill string sections, then the drill string can be assembled or disassembled, but re-starting mud circulation is required which is time consuming
Solution Approach 1:
The valve assembly enables drilling fluid circulation to continue uninterrupted during drill string assembly and disassembly operations. By providing a bypass passage that remains open during connection operations, the system eliminates the time-consuming process of stopping and re-starting mud circulation, significantly reducing operational downtime.
4Ease of manufacture
If drilling fluid circulation is stopped when adding or removing drill string sections, then the drill string can be assembled or disassembled, but expensive mud weight adjustments are required
Solution Approach 1:
The valve assembly maintains continuous drilling fluid circulation during assembly operations, eliminating the need to adjust mud weight to compensate for circulation stoppage. By keeping fluid flowing continuously, the system prevents the formation damage and pressure changes that would otherwise require expensive mud weight modifications.
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
Enables uninterrupted drilling fluid circulation during the addition or removal of drill string sections, reducing the risk of formation damage and overpressuring, and minimizing the need for re-starting mud circulation, thus improving drilling efficiency and reducing operational costs.
Implementation Method 1
one or more bearings disposed between the housing and the sleeve/case, the bearings supporting rotation of the housing relative to the sleeve/case
Implementation Method 2
one or more seals disposed between the housing and the sleeve/case and providing a sealed fluid path between the sleeve/case port and the housing port
Data Source
Figure 1~1B
Figure 2~2A
Figure 3~3A
AI summary
A method for drilling a wellbore comprises drilling the wellbore by rotating a tubular string (8) using a top drive (50) and advancing the tubular string longitudinally into the wellbore. An upper portion of the tubular string having a side port (150) is rotationally unlocked from the rest of the tubular string. A tubular joint or stand of joints is added to the upper portion while drilling fluid is injected into the side (150) port and the rest of the tubular string is rotated using a rotary table The upper portion is rotationally locked to the rest of the tubular string after adding the joint or stand. Drilling of the wellbore is resumed after the upper portion is rotationally locked.