Drill String Bypass Device for Hole Cleaning and ECD Management
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Solution Overview
Problem
In drilling wellbores, especially in highly deviated wells, cuttings tend to settle and not efficiently flow to the surface due to inadequate circulating fluid flow rate, and there is a need to manage equivalent circulation density (ECD) to reduce pressure at the wellbore bottom.
Innovation Solution
A bypass device with a fluid passage is used in the drill string, equipped with sensors to measure flow rate and mechanical motion, which activates to divert fluid to the annulus when specific flow rate and motion parameters are detected, allowing for controlled fluid diversion and flow pattern alteration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drilling fluid is supplied through the drill string at high flow rate, then cuttings can be efficiently carried to the surface, but pressure at the wellbore bottom (ECD) increases
Solution Approach 1:
The drilling fluid flow path is segmented into two separate paths: (1) through the drill string to the drill bit for rock cutting, and (2) through the bypass device directly into the annulus for hole cleaning. This segmentation allows independent control of each flow path, enabling cuttings to be carried upward through the annulus without requiring high drill string flow rates that would increase ECD.
Solution Approach 2:
The bypass device acts as an intermediary component that introduces drilling fluid directly into the annulus bypassing the drill string. This intermediary flow path enables fluid to reach the annulus without passing through the drill string, thereby reducing pressure buildup at the wellbore bottom while still providing sufficient flow for hole cleaning.
2Productivity
If drilling fluid flow rate is increased to prevent cuttings settlement, then hole cleaning improves, but device complexity increases due to need for flow control mechanisms
Solution Approach 1:
The bypass device incorporates a movable bypass member that can dynamically change position between open and closed states. This dynamic mechanism allows the device to adapt to different drilling conditions, enabling flow diversion when needed and normal operation when not needed, thereby improving hole cleaning efficiency without requiring complex permanent flow control structures.
Solution Approach 2:
The bypass device utilizes changes in flow rate parameters to activate the bypass function. When the drilling fluid flow rate reaches a predetermined threshold, this parameter change triggers the bypass member to open, automatically diverting excess flow into the annulus. This parameter-based activation simplifies the control mechanism compared to continuously adjustable flow control systems.
3Productivity
If bypass device is continuously activated to divert fluid to annulus, then hole cleaning improves, but loss of drilling fluid through drill string increases
Solution Approach 1:
The bypass device operates periodically rather than continuously, activating only when cuttings settlement is detected or when flow rate reaches predetermined thresholds. This periodic operation allows the system to maintain normal drill string flow during periods when hole cleaning is adequate, thereby minimizing unnecessary drilling fluid diversion and reducing overall fluid loss.
Solution Approach 2:
The system incorporates sensors that monitor annular flow conditions and provide feedback to the bypass device control mechanism. When sensors detect that sufficient flow is already present in the annulus or that hole cleaning is adequate, this feedback signal closes the bypass member, preventing further fluid diversion. This feedback-controlled operation optimizes hole cleaning while minimizing drilling fluid loss.
Data Source
AI summary
A method and apparatus for drilling a wellbore is disclosed. The wellbore is drilled with a drill string that includes a bypass device having a fluid passage therethrough by supplying a fluid through the bypass device at a first flow rate, wherein the fluid circulates to a surface location via an annulus between the drill string and the wellbore. The flow rate of the fluid is altered to a second flow rate. A time period is defined and a mechanical motion of the bypass device is initiated. A parameter related to the mechanical motion of the bypass device and a parameter related to flow rate are detected. The bypass device is activated to divert a portion of the fluid to the annulus when the parameter related to mechanical motion is detected and the parameter related to flow rate is present during the defined time period.