Introduction; Principle Of Operation - Geokon 4500HT Series Instruction Manual

1. INTRODUCTION

Geokon's 4500HT Series High Temperature Piezometers and Pressure Transducers are
designed for monitoring downhole pressures and temperatures in oil recovery systems
and geothermal applications.
These sensors are capable of operation under extreme conditions and at temperatures
up to 250°C. In thermal recovery applications (steam assisted gravity drainage (SAGD)
or cyclic steam stimulation (CSS)), they can provide accurate, real-time, continuous
monitoring of pressures in production and injection wells thereby optimizing the recovery
rate and reducing the costs of the steam injection process. In geothermal applications,
they offer a means for in situ and continuous monitoring of pressures and temperatures
over extended periods of time.
Figure 1 Model 4500HT high temperature pressure transducer

2. PRINCIPLE OF OPERATION

The sensor utilizes a sensitive stainless steel diaphragm to which a vibrating wire
element is connected. See Figure 2. In use, changing pressures on the diaphragm
cause it to deflect, and this deflection is measured as a change in tension and frequency
of vibration of the vibrating wire element. The square of the vibration frequency is