THE EFFECT OF PORE STRUCTURE ON PRIMARY DRAINAGE CAPILLARY BEHAVIOUR

摘要

This work records the results of a special core analysis(SCAL)project performed by the author at the Integrated Core Consultancy Services(ICCS)laboratory facility at Sunburyon-Thames,London,UK.The present study tries to explain the difference of irreducible water saturation between drainage capillary pressure curves obtained from two techniques(mercury injection and porous plate combined with GASM).With this goal,a series of drainage experiments was systematically achieved.Each test consisted of measuring capillary pressure by two techniques on two adjacent samples : mercury injection with capillary pressure values up to 60.000 psia was used on one sample and air/brine porous plate under conditions of reservoir confining stress utilizing a developed gamma ray(GASM)monitoring system.For this system,sources and detectors are mounted in fixed positions so that the core holder and core matrix remain unchanged during the displacement test.All of the samples(06)chosen for study had previously been characterized in terms of pore structure by basic mercury intrusion testing.The origin of the modes of microporosity known to be present after this characterization was confirmed by X-ray diffraction mineralogical assay.As many samples were chosen as was feasible to characterize within the overall time constraints of the project,whilst possessing as much variety in pore structure and mineral content as possible.Standard values of contact angle and interfacial tension given in nomenclature were used to convert mercury data to equivalent air/brine capillary data.