Use of Borehole Gravimetry for Reservoir Characterisation and Fluid Saturation Monitoring

Abstract

ABSTRACT This paper describes the results of a field application of borehole gravimetry to measure secondary gas saturations in a fractured limestone reservoir. Owing to its deep-reading capability and insensitivity to near-wellbore effects, the borehole gravimeter succeeded where conventional cased-hole logging methods had failed. Borehole-fluid pressure data, recorded together with the gravity data, proved useful in ensuring that the density data had the necessary high accuracy. This paper additionally presents modelling results that indicate the potential usefulness of time-lapse borehole gravity data for monitoring floodfronts remote from a borehole. This application would benefit from the development of a sensor with a very reliable absolute calibration and low drift.