Flow Stop Valve for Downhole Tubular Pressure Control
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Solution Overview
Problem
Dual density drilling fluid systems face challenges due to hydrostatic pressure imbalances between fluids inside and outside the tubular, leading to uncontrollable fluid flow and increased costs and time in deep sea drilling operations.
Innovation Solution
A flow stop valve is designed to be positioned in a downhole tubular, which includes a housing with a sleeve and spring mechanism that prevents fluid flow until a specific 'cracking' pressure is reached, equalizing pressures and allowing controlled flow, thereby addressing the pressure imbalances and enabling deeper drilling with reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dual density drilling fluid systems are used to match pressure gradients, then drilling depth and efficiency are improved, but hydrostatic pressure imbalance causes uncontrollable fluid flow between tubular and formation
Solution Approach 1:
The flow stop valve is pre-installed in the tubular before drilling operations begin. The valve remains closed during drilling, preventing fluid communication between the tubular interior and exterior. When drilling is complete and the valve is to be opened, the preliminary closure ensures pressure balance is maintained throughout the operation, eliminating uncontrollable fluid flow while enabling deep drilling with dual density fluids
Solution Approach 2:
The flow stop valve acts as an intermediary device between the dual density drilling fluid system and the formation. By controlling fluid communication at this intermediate point, the valve mediates the pressure imbalance issue, allowing the dual density system to function effectively without causing harmful fluid migration between the tubular and formation
2Adaptability or versatility
If density of drilling fluid is adjusted at seabed to match seawater, then pressure gradient follows formation pressures over wider depth range, but hydrostatic pressure imbalance occurs between single density fluid in tubular and dual density fluid outside
Solution Approach 1:
The flow stop valve extracts or removes the source of pressure imbalance by preventing fluid communication between the single density fluid inside the tubular and the dual density fluid outside. By taking out the problematic fluid interface, the system can maintain different density profiles without experiencing harmful hydrostatic pressure imbalances
Solution Approach 2:
The closed valve applies preliminary anti-action by blocking fluid flow before pressure imbalance can cause harmful effects. This preventive measure counteracts the potential for uncontrolled fluid migration, allowing the pressure gradient adaptation benefits to be realized without the associated risks
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 flow stop valve effectively prevents uncontrollable fluid flow by ensuring that drilling fluid only flows when the 'cracking' pressure is applied, maintaining pressure balance and allowing for deeper drilling operations with reduced costs and time.
Implementation Method 1
A flow stop valve is designed to be positioned in a downhole tubular, which includes a housing with a sleeve and spring mechanism
Implementation Method 2
prevents fluid flow until a specific 'cracking' pressure is reached, equalizing pressures
Data Source
Figure 1a~1b
Figure 1c
Figure 2
AI summary
A flow stop valve (120) positioned in a downhole tubular (6), wherein: the flow stop valve (120) is in a closed position when a pressure difference between fluid outside the downhole tubular (6) and inside the downhole tubular (6) at the flow stop valve (120) is below a threshold value, thereby preventing flow through the downhole tubular; and the flow stop valve (120) is in an open position when the pressure difference between fluid outside the downhole tubular (6) and inside the downhole tubular (6) at the flow stop valve (120) is above a threshold value, thereby permitting flow through the downhole tubular (6).