Mid-String Mud Cap Tool for Fluid Diversion Between Lost Circulation Zones
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Solution Overview
Problem
Conventional methods for maintaining hydrostatic pressure in wellbores with multiple lost circulation zones fail to effectively deliver drilling fluid to the sections between these zones, leading to potential wellbore collapse and stuck pipe issues.
Innovation Solution
A mid-string mud cap tool with a ball seat and ports that diverts a portion of the drilling fluid into the annulus between lost circulation zones, ensuring a continuous hydrostatic fluid column and targeted fluid delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drilling methods are used in wellbores with multiple lost circulation zones, then drilling operations can proceed without additional equipment, but hydrostatic pressure cannot be maintained in sections between lost circulation zones leading to wellbore collapse and stuck pipe
Solution Approach 1:
The drilling system is segmented by inserting a mid-string mud cap tool at a specific position within the drill string. This tool divides the continuous drill string into upper and lower sections, allowing independent fluid management. The tool includes separate ports (first port for receiving drilling fluid, second port for discharging into annulus) that enable targeted fluid delivery to specific zones between lost circulation zones, thereby maintaining wellbore stability without complicating the entire drilling system.
Solution Approach 2:
The mid-string mud cap tool acts as an intermediary device between the drilling fluid supply system and the annulus. It receives drilling fluid through its first port and selectively discharges a portion through its second port into the annulus at a location between lost circulation zones. This intermediary function allows precise control over fluid placement, maintaining hydrostatic pressure where needed while keeping the rest of the drilling system relatively simple.
2Reliability
If drilling fluid is pumped continuously through the drillstring, then the drill bit receives adequate fluid for cooling and cuttings removal, but sections of the wellbore between lost circulation zones do not receive sufficient fluid to maintain hydrostatic pressure
Solution Approach 1:
The mid-string mud cap tool implements local quality by providing different fluid flow paths at different locations. The first port receives drilling fluid under pressure, and the second port selectively discharges a portion of this fluid into the annulus at a specific location between lost circulation zones. This localized fluid injection ensures that hydrostatic pressure is maintained precisely where needed (in the vulnerable section between lost circulation zones) while the majority of the drilling fluid continues to flow efficiently to the drill bit for cooling and cuttings removal.
3Reliability
If a mid-string mud cap tool is inserted to divert fluid to the annulus, then hydrostatic pressure is maintained between lost circulation zones, but the drilling fluid volume available for the drill bit is reduced
Solution Approach 1:
The mid-string mud cap tool applies partial action by diverting only a portion of the drilling fluid into the annulus through the second port, rather than diverting all of it. The first port continues to receive the full volume of drilling fluid pumped through the drillstring, and the tool selectively discharges a controlled portion into the annulus at the second port. This partial diversion maintains hydrostatic pressure in the critical zone between lost circulation zones while ensuring adequate fluid volume remains available for drill bit cooling and cuttings removal.
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 mid-string mud cap tool reduces the risk of wellbore collapse and stuck pipe by maintaining hydrostatic pressure and improving drilling efficiency through strategic fluid delivery, minimizing non-productive time and costs.
Implementation Method 1
a ball seat provided within the interior downhole from the one or more ports. The well system may further include a wellbore projectile conveyable into the drillstring and sized to land on the ball seat, wherein the mid-string mud cap tool may be arranged within the wellbore at a location between the first and second lost circulation zones, and wherein landing the wellbore projectile on the ball seat causes a portion of drilling fluid circulating within the drillstring to circulate into the annulus via the one or more ports
Data Source
AI summary
A well system includes a drillstring extended within a wellbore penetrating first and second lost circulation zones, a drill bit arranged at a downhole end of the drillstring, and a mid-string mud cap tool included in the drillstring and arranged uphole from the drill bit. The mid-string mud cap tool includes a body that defines an interior, one or more ports defined in the body to facilitate fluid communication between the interior and the annulus, and a ball seat provided within the interior. A wellbore projectile is conveyable into the drillstring to land on the ball seat. The mid-string mud cap tool is arranged at a location between the lost circulation zones, and landing the wellbore projectile on the ball seat causes a portion of drilling fluid circulating within the drillstring to circulate into the annulus via the ports and between the lost circulation zones.