Downhole Tool Fluid Mixing for Sampling Control
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Solution Overview
Problem
Current methods for sampling and testing formation fluid in subterranean formations face challenges in controlling the concentration of formation fluid and maintaining a differential pressure during the sampling operation, which affects the efficiency and accuracy of fluid extraction and analysis.
Innovation Solution
A downhole tool with first and second fluid ports is used to mix wellbore fluid with formation fluid, controlled by a controller to manage the concentration of formation fluid in the output mixture, ensuring a differential pressure that corresponds to an overbalance condition in the annulus, facilitating efficient extraction and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If formation fluid is extracted and stored in the formation sampling tool, then the formation fluid can be tested and analyzed, but the concentration of formation fluid cannot be precisely controlled and differential pressure cannot be maintained
Solution Approach 1:
The sampling tool is divided into multiple functional segments: a sampling section with formation fluid intake, a mixing section with wellbore fluid injection, and a discharge section. This segmentation allows independent control of formation fluid sampling and wellbore fluid mixing, enabling precise concentration control without overwhelming system complexity
Solution Approach 2:
Wellbore fluid is introduced as an intermediary substance to mix with the formation fluid. This intermediary allows control of the formation fluid concentration in the output mixture by adjusting the wellbore fluid flow rate, thereby achieving precise concentration control while maintaining differential pressure through the mixing process
2Stress or pressure
If wellbore fluid is pumped into the drill string to circulate through the annulus, then the annulus pressure can be controlled, but the differential pressure between wellbore fluid and formation fluid cannot be maintained
Solution Approach 1:
The system dynamically adjusts the flow rates of both wellbore fluid and formation fluid based on real-time differential pressure conditions. By continuously monitoring and adjusting the wellbore fluid injection rate, the system maintains optimal differential pressure while maximizing formation fluid extraction efficiency
Solution Approach 2:
The system changes operational parameters including wellbore fluid flow rate, formation fluid intake rate, and mixing ratio to maintain the desired differential pressure. By adjusting these parameters, the system ensures both adequate pressure differential for efficient extraction and precise concentration control in the output mixture
3Measurement precision
If formation fluid is extracted without controlling concentration, then the sampling operation is simpler, but the analysis accuracy is reduced
Solution Approach 1:
The system incorporates feedback control where the concentration of formation fluid in the output mixture is monitored and used to adjust the wellbore fluid injection rate. This feedback mechanism ensures accurate analysis by maintaining the desired formation fluid concentration while automating the control process to preserve operational simplicity
Solution Approach 2:
The mixing section is designed to automatically regulate the concentration of formation fluid through the interaction between wellbore fluid injection and formation fluid intake. The system self-adjusts the mixing ratio based on flow rate relationships, providing accurate concentration control without requiring complex manual intervention
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 solution enables precise control of formation fluid concentration and pressure, enhancing the efficiency and accuracy of fluid sampling and analysis by maintaining an optimal differential pressure, thereby improving the overall sampling process.
Implementation Method 1
The wellbore fluid and the formation fluid may then mix within the downhole tool to form an output mixture
Implementation Method 2
The controller may control a differential pressure between the wellbore fluid in the annulus and the output mixture in the interior bore during a formation sampling operation
Implementation Method 3
The wellbore fluid may flow downwardly through the drill string and may exit the drill string via ports in a drill bit. The wellbore fluid may then circulate upwardly through the annulus region.
Data Source
AI summary
An apparatus disclosed herein includes a downhole tool having a body defining an interior bore and an exterior surface. The example apparatus also includes first and second fluid ports to provide respective fluid paths between the exterior surface and the interior bore. The first fluid port is to receive wellbore fluid from an annulus of a wellbore in which the downhole tool is to be disposed and the second fluid port is to receive formation fluid extracted from a subterranean formation. The formation fluid is to mix with the wellbore fluid to form an output mixture in the interior bore. The example apparatus also includes a controller to control a concentration of the formation fluid in the output mixture.