A Sensing Microsystem for High Resolution Pressure Gradient Measurement in Core-Flood Experiments

Investigating the permeability and porosity of geological samples is a routine element of geological studies, and of particular interest to the oil and gas industry. Core-flood experiments are commonly performed on rock samples to measure transport characteristics in the laboratory. This paper reports the design and implementation of a high resolution distributed pressure measurement system for core-flood experiments. A series of microfabricated pressure sensors are embedded in bolts housed within the pressurized polymer sheath that encases the rock core. A feedthrough technology has been developed to provide lead transfer between the sensors and system electronics across a 230-bar pressure difference. The system has been successfully benchtop tested with fluids such as synthetic oil and/or gas. Pressure measurements were recorded over a dynamic range of 20 bar with a resolution as small as 0.3 mbar.