Downhole Electrochemical Sensor for Fluid Composition Analysis
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Solution Overview
Problem
Current downhole sensors lack the capability to accurately measure and analyze the chemical composition and parameters of downhole fluids, particularly for gases like H2S, CO2, and CH4, which are crucial for evaluating hydrocarbon reserves and ensuring safe drilling operations.
Innovation Solution
An electrochemical sensor system is deployed in a downhole tool, featuring a membrane-exposed electrochemical cell with multiple sensors, including analyte, temperature, and pH sensors, capable of generating electrical signals to measure fluid parameters through reactions with the sensing solution, and utilizing square wave and cyclic voltammetries to determine mediator concentration and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional downhole sensors are used, then device complexity is reduced, but measurement precision of chemical composition and gas parameters is insufficient
Solution Approach 1:
The patent combines multiple sensor types (electrochemical cell with analyte sensor, pH sensor, temperature sensor) into a single integrated downhole sensor assembly. This merging approach enables simultaneous measurement of multiple chemical parameters and physical conditions, improving measurement precision while managing device complexity through unified design and shared housing structure.
Solution Approach 2:
The electrochemical sensor system is designed with multi-functionality to measure various downhole fluid parameters including gas composition (H2S, CO2, CH4), pH, and temperature simultaneously. The single sensor assembly serves multiple measurement purposes, enhancing the system's capability to evaluate hydrocarbon reserves and ensure safe drilling operations without requiring separate specialized sensors for each parameter.
2Measurement precision
If multiple sensors are integrated into the electrochemical cell, then measurement precision improves, but device complexity increases
Solution Approach 1:
Multiple sensing elements including the electrochemical cell with analyte sensor, pH sensor, and temperature sensor are merged into a single integrated assembly that shares a common housing and measurement chamber. This consolidation allows simultaneous measurement of multiple fluid parameters with improved precision while the shared structural elements help manage the overall device complexity.
3Reliability
If the membrane is exposed to downhole fluid, then detection capability improves, but reliability decreases due to potential contamination or damage
Solution Approach 1:
A selective permeable membrane is employed as a protective barrier between the downhole fluid and the electrochemical cell's sensing elements. This thin film allows specific gases (H2S, CO2, CH4) to diffuse through to the sensor while blocking other contaminants and harmful substances, thereby maintaining sensor reliability and detection capability in the harsh downhole environment.
Solution Approach 2:
The selective permeable membrane acts as an intermediary substance that mediates between the downhole fluid and the sensor. It selectively permits certain gases to pass through while preventing direct contact between the fluid and the sensor's internal components, thus protecting the sensor from contamination and damage while still enabling accurate detection of target analytes.
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
This system effectively measures downhole fluid parameters, enabling accurate detection of gases and chemical composition, which aids in evaluating hydrocarbon reserves and ensuring safe drilling operations by preventing corrosion and other operational hazards.
Implementation Method 1
The sensing solution is reactive to certain analytes in the downhole fluid to generate electrical signals measurable by the cell sensors whereby parameters of chemicals in the downhole fluid may be measured
Implementation Method 2
a membrane exposed to the downhole fluid in the flowline
Data Source
AI summary
An electrochemical sensor of a downhole tool positionable in a wellbore penetrating a subterranean formation is provided. The downhole tool has a flowline to receive downhole fluid. The electrochemical sensor includes a bulkhead carried by the downhole tool, a membrane exposed to the downhole fluid in the flowline, and an electrochemical cell supported by the bulkhead about the membrane. The electrochemical cell includes a plurality of cell sensors, at least one cell electrode, and a sensing solution. The plurality cell sensors include an analyte sensor, a temperature sensor, and a pH sensor. The sensing solution is reactive to certain analytes in the downhole fluid to generate electrical signals measurable by the plurality of cell sensors whereby parameters of chemicals in the downhole fluid may be measured.