A Fast and Direct Method of Permeability Measurements on Drill Cuttings

摘要

Permeability is one of the most important petrophysicalrnparameter for reservoir characterization but the most difficultrnto obtain. Logs provide a good estimate of porosity andrnsaturations, but the accuracy on permeability derived fromrnNMR is rather poor. So far, reliable values of permeabilitiesrnare only obtained from laboratory measurements on corernsamples for local measurements and well testing for a largerrnscale averaged determination.rnWe present an original method for measuring the permeabilityrnof drill cuttings without any specific laboratory conditioningrn(cleaning, coating, etc.). A volume of about 100 cc of cuttingsrnis placed in a pressure vessel. The cell is then filled with arnviscous oil. The process of oil invasion into the cuttingsrnalways traps a certain amount of gas. When a pulse of pressurernis applied on the cell, the oil enter into the cuttings thanks tornthe gas compressibility. The permeability is then derived fromrnthe dynamic of the oil invasion by using a simple model.rnThe method was tested by using various samples of crushedrnrock samples of known permeability. An excellentrnreproducibility and a good agreement between cores andrncuttings permeabilities were found for many decades ofrnpermeabilities. This method presents many advantages. Thernmeasurements can be performed in a few minutes, leading tornthe possibility of operating on-site during drilling. Thernlimitations of the method are mainly related to the size and thernrepresentativity of the drill cuttings.rnIn developing this method, our purpose is not to replace corernanalysis, but rather to provide an additional cheap and quickrninformation on reservoir characterization.