Three-Way Flow Sub for Continuous Drilling Circulation
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Solution Overview
Problem
Drilling operations face interruptions and formation damage due to the need to stop circulation when adding or removing drill string joints, leading to time consumption and potential wellbore damage, and the challenge of maintaining mud weight for static head and formation pressure balance.
Innovation Solution
A three-way flow sub with a tubular housing, bore valve, and sleeve mechanism that allows continuous circulation by isolating sections of the drill string, enabling fluid injection and joint addition without stopping the drilling process, using a bore valve actuator to manage fluid flow and maintain circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drilling operations stop to add or remove drill string joints, then the drill string can be maintained at proper length, but circulation of drilling fluid stops causing time loss and potential wellbore damage
Solution Approach 1:
The flow sub divides the drill string into isolated segments using valve sections with bore valves and port valves. This segmentation allows one section to be opened for adding drill pipe while another section maintains closed circulation, enabling continuous drilling operations without stopping fluid circulation throughout the entire drill string.
Solution Approach 2:
The invention enables continuous circulation of drilling fluid by maintaining closed valve sections while opening port sections for drill string modification. The bore valve and port valve mechanism ensures that fluid circulation never stops, eliminating downtime and preventing wellbore damage that occurs when circulation is interrupted.
2Ease of manufacture
If drilling fluid circulation stops, then drill string joints can be added or removed, but cuttings settle in the fluid causing formation damage
Solution Approach 1:
The flow sub segments the drill string into isolated valve sections that can be opened individually. This allows the system to maintain closed circulation in most sections while opening only the specific section needed for adding drill pipe, preventing cuttings settlement in open sections while maintaining suspension in closed sections.
Solution Approach 2:
By maintaining continuous circulation through closed valve sections while opening port sections for drill string modification, the system prevents cuttings from settling anywhere in the drill string. The continuous fluid motion keeps cuttings suspended even during drill pipe additions.
3Stress or pressure
If mud weight is increased to maintain static head during drill string modifications, then pressure balance is maintained, but pumping power requirements increase
Solution Approach 1:
The continuous circulation enabled by the flow sub eliminates the need to increase mud weight during drill string modifications. Since circulation never stops, the existing mud weight continuously provides sufficient pressure balance, avoiding the energy-intensive requirement to pump heavier mud that would be needed if circulation stopped and static head had to be maintained.
Data Source
Figure 1A
Figure 1B~1C
Figure 2A~2C
AI summary
A flow sub for use with a drill string includes: a tubular housing having a longitudinal bore formed therethrough and a flow port formed through a wall thereof; a bore valve operable between an open position and a closed position, wherein the bore valve allows free passage through the bore in the open position and isolates an upper portion of the bore from a lower portion of the bore in the closed position; and a sleeve disposed in the housing and movable between an open position where the flow port is exposed to the bore and a closed position where a wall of the sleeve is disposed between the flow port and the bore; and a bore valve actuator operably coupling the sleeve and the bore valve such that opening the sleeve closes the bore valve and closing the sleeve opens the bore valve.