Downhole electrochemical sensor and method of using same

摘要

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.

主权项

1. An electrochemical sensor of a downhole tool positionable in a wellbore penetrating a subterranean formation, the downhole tool having a flowline to receive downhole fluid, the electrochemical sensor comprising:
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 adjacent the membrane, the electrochemical cell comprising a plurality of cell sensors, at least one cell electrode, a sensing solution, and a mediator sensor, the plurality of cell sensors comprising an analyte sensor, a temperature sensor, and a pH sensor, the sensing solution 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, wherein the analyte sensor measures square wave and cyclic voltammetry, wherein the temperature sensor measures temperature using a calibration model, wherein the pH sensor measures square wave voltammetry, and wherein the mediator sensor determines a mediator concentration of the sensing solution from the square wave, the current-voltage relationship, and the pH, and whereby the mediator concentration, the current-voltage relationship, and the pH combine with the temperature to determine a concentration of the analyte of the downhole fluid in the flowline, and whereby the concentrate of the analyte combines with the measured pressure to measure pressure of the downhole fluid in the flowline and to determining a partial pressure of the analyte within the flowline, using a gas solubility model.