Probe permeametry applied to a highly laminated sandstone reservoir

Abstract

Approximately 5200 permeability measurements were made with an automated probe permeameter on 5 m of centre cut core from a North Sea well. The material studied is from the Lower Jurassic Cook Formation sandstone reservoir, which here is heterogeneous in nature. It consists of highly laminated sandstone/shale interbedding with lamina or bed thickness ranging from a few tenths of a millimetre to upwards of 10 cm. The aim of the study was to investigate the probe response in such material and to determine the permeability distribution at a smaller scale of investigation than that possible using core plugs. Fine grid measurements (1 mm sampling density) supported by conventional plug measurements show that the three order of magnitude permeability variations measured are directly related to sedimentary features. Different facies can be defined, each with an associated probe permeameter response and corresponding permeability range, and combined with the measured distribution, the fraction of each facies is calculated. Given a definite permeability range, the amount of each facies as a fraction of the whole may be determined with an accuracy of ±0.01–0.02.