Potentiometric-model Studies of Fluid Flow in Petroleum Reservoirs

A simplification of the method of Hurst and McCarty for conductingpotentiometric model studies by the single probe method is presented along withexperimentally determined invasion patterns for certain idealized flowproblems. The analytical solution for one class of these problems is given.Finally, a general description is given of a newly developed instrument whichpermits direct mapping of flow lines and determination of transit times inpotentiometric-model studies. Introduction The object of this paper is to present:A simplification of the method of Hurst and McCarty for conductingpotentiometric-model studies of oil and gas reservoirs by the single probemethod.Results of a series of studies of certain idealized flow problems and thegeneral conclusions to be drawn therefrom.A description of a dew instrument, the Chronocartograph, which greatlyreduces the labor and time required for conducting potentiometric-modelstudies. Certain general conclusions may be drawn as results of theinvestigation of the idealized flow problems. They are:Injection and extraction areas should be separated by as great a distance asconditions permit since, in general the recovery prior to first breakthroughtends to vary as the square of this distance.Little advantage is to be gained by use of more than eight injection wellsor groups of injection wells for the case of circular productive limits.Elongated shapes if productive limits are best exploited by injection on theextended major axis only, with a line of extraction wells lying on the majoraxis.The use of peripheral injection wells for elongated shapes is permissible, if necessary, but requires extension of the lines of extraction wells. The exploitation of an oil or gas field is effected either by the expansion ofthe gas and oil, or by their displacement by another fluid. Both methods may beused simultaneously. When the displacement of the oil or gas is the controllingfactor there arises the problem of mapping the progress of the boundary betweenthe fluid in place and the displacing fluid. This problem is of particularinterest in the operation of a cycling project in a gas-condensate field, wherethe wet gas is produced from one or more wells, commonly called ?extractionwells?. This wet gas is taken into a processing plant where the condensate isremoved. The remaining "dry" gas is injected back into the field through one ormore wells, the gas for future use and also to maintain the pressure in thefield. T.P. 2262