Development, qualification, and performance validation of an optical differential pressure sensor for downhole permanent monitoring applications

Abstract

This paper describes the development, qualification, and performance validation of an optical differential pressure (DP) sensor for the high-pressure and high-temperature downhole environment. The current implementation of measuring DP in downhole applications is based on the calculated difference between two static pressure sensor measurements with high uncertainties. A true DP sensor is superior in comparison due to the decreased uncertainty both in measurement and component levels. This translates to better performance in system level measurements such as flow. A development program was launched in 2007 to build an optical DP sensor targeted for two main applications: standalone use in single-phase or auxiliary use in multiphase flow measurement systems. Several prototypes have gone through multiple design phases and qualification test programs including mechanical shock and vibration tests, thermal tests, hot vibration tests, short-term stability and long-term endurance tests. The sensor was then integrated with a Venturi and tested in a single-phase flow loop to validate its performance against an electronic DP sensor and an electromagnetic flowmeter. Results suggest that optical DP sensor performs better than the electronic DP sensor in measuring differential pressures, and is on a par with the electromagnetic flowmeter.