Downhole Electrochemical Sensor Fluid Contamination Monitoring
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Solution Overview
Problem
Challenges arise in obtaining pure, uncontaminated fluid samples from subsurface formations during drilling operations due to contamination from drilling mud filtrate, making it difficult to conduct valid hydrocarbon fluid analysis.
Innovation Solution
A method utilizing an electrochemical sensor operable at high temperature and pressure conditions to differentiate between mud filtrate and reservoir fluid by measuring specific chemical species, allowing for the detection of stabilization of fluid properties in the flowline, ensuring the collection of clean reservoir fluid samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fluid is sampled through the borehole, mudcake, cement and/or other layers, then fluid can be obtained from the formation, but the fluid becomes contaminated with drilling mud filtrate making it unacceptable for hydrocarbon fluid sampling
Solution Approach 1:
The patent applies preliminary action by implementing a clean-up phase before sampling where the probe pumps fluid through the mudcake and contaminated zones to clear the flow path. This preliminary pumping action removes drilling mud filtrate and contaminants from the invaded zone, ensuring that subsequent samples represent only virgin formation fluid. The system monitors fluid properties during this clean-up phase to determine when contamination has been sufficiently removed.
2Object-affected harmful factors
If the probe pumps fluid to clear the flow path of contamination, then contamination is reduced, but time is lost during the clean-up phase
Solution Approach 1:
The patent implements feedback by continuously monitoring fluid properties (such as resistivity, density, or chemical composition) during the clean-up phase and using this information to determine when the fluid has been sufficiently cleaned and is ready for sampling. This feedback mechanism allows the system to automatically terminate the clean-up phase when contamination reaches acceptable levels, optimizing the balance between contamination removal and time consumption without requiring fixed predetermined pumping durations.
3Measurement precision
If multiple fluid properties are monitored, then contamination detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a downhole tool that can monitor multiple fluid properties (such as resistivity, density, temperature, and chemical composition) using integrated sensors and measurement systems. This multi-functional approach allows a single device to perform contamination detection, fluid characterization, and sampling control, thereby improving detection accuracy while avoiding the need for multiple separate specialized devices.
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
Enables accurate monitoring and differentiation between contaminated and virgin fluid, optimizing the sampling process by determining the appropriate time to capture representative fluid samples, reducing contamination and improving the accuracy of hydrocarbon evaluations.
Implementation Method 1
measuring a property of the fluid in the flowline with an electrochemical sensor, the fluid property being a physical property of the fluid that distinguishes between mud filtrate and reservoir fluid
Data Source
AI summary
A method of evaluating a fluid from a subterranean formation drawn into a downhole tool positioned in a wellbore penetrating the subterranean formation is provided. This method involves drawing fluid from a formation into a flowline, measuring at least one property of the fluid in the flowline and detecting stabilization of the property or properties of the fluid in the flowline. An electrochemical sensor for measuring contents of a fluid or gas at high pressure and/or high temperature may be used.