This paper presents a novel circuit methodology for rejecting the random DC drift associated with recording microelectrodes. In this approach, a sub-threshold front end MOS transistor is used as a voltage variable resistor to clamp the large, and random DC drifts at the recording site without sacrificing AC performance. A CMOS amplifier utilizing this front-end stage (along with DC common mode feedback) has been fabricated. The amplifier measures 0.1 8 sq. mm. and has a closed loop gain of 41 dB with a power consumption of 150 pW. The system provides -30 dB of DC attenuation, and has a CMRR of 35 dB.

Corrosion and related issues are a major contributor in failures of electrical submersible pumps (ESP). This paper describes the development and preliminary testing of a new downhole corrosion sensor to be integrated into ESPs for providing continuous monitoring. We will describe the development of a downhole sensor, testing and applications of such a sensor. In-situ corrosion monitoring provides valuable and actionable data that enables implementation of mitigation strategies before damages occur and allow for planned servicing. It ultimately allows operators to make informed decisions on corrosion control and ESP maintenance scheduling.

Sensors are becoming increasingly ubiquitous in the oil and gas industry to enhance efficiency in exploration and production (E&P), as well as to improve safety and minimize the impact of these operations on the environment. In particular, knowledge of the properties of fluids contained in a hydrocarbon reservoir helps to identify the fluid type, estimate reserves, assess hydrocarbon value and optimize production. Although measurement of fluid properties can be done at the rig surface or downhole, the latter is preferred because subjecting these fluids to changes in pressure and temperature compared to the downhole environment may induce irreversible changes. Moreover, in many instances, it is important to monitor the chemical composition of a fluid in real time. Dissolved H2S in reservoir fluids has a harmful impact on cost and safety operations in drilling and production. We have investigated localized surface plasmon resonance (LSPR) methodologies and fabricated sensors for measuring dissolved sulfides in liquids. The impact of the specificity of sensing materials and the design concepts were investigated. The chemical composition and morphology of the nanoparticles affect the response of the sensor, and can be used to mitigate the strong absorption in heavy crudes. The effect of temperature on the sensor response was evaluated. Sensor response was not affected below 150o F. The effect of organo-sulfur compounds on sensor response was also investigated.

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