Abstract To obtain accurate data for use in calculating vertical fluid flow within a reservoir, in situ measurements of vertical permeability were conducted on five wells in the South Swan Hills Unit. These measurements quantified the permeability parameters for subsequent model studies of the Light Brown member of the Beaverhill Lake formation. This paper presents a description of the data collection technique employed and the results for the vertical permeability measurements. Included in the discussion is a treatment of the data analysis for a single measurement utilizing: (1) the two techniques presently available in literature (1,2) and (2) a numerical reservoir simulator. Based on the data obtained and the results of the testing as discussed in this paper, it can be concluded that a viable technique is available for measuring vertical permeability. Additional refinements in the field operations associated with this type of pressure testing can be made, but overall a success ratio of 100% should not be expected. The successful application of this type of measurement to relating core analysis data to the needs of an adequate reservoir description should be of interest to any performance study. Introduction Every reservoir engineer has probably recognized that the single, most important contributing factor to a useful simulation is the description of the reservoir being studied. The reservoir description must include permeability values which, will govern the fluid flow within the model. These data are generally obtained from core analysis and may be tailored to reflect information available from pressure transient testing of producing or injection wells. In the case of three dimensional or two dimensional cross sectional studies the vertical as well as the horizontal permeability must be quantified. Since one usually uses point source values for vertical permeability in a heterogenous reservoir. serious consideration must be given to validating the data with in situ measurements. The real question is two-fold, firstly, does the core analysis data reflect the properties of the surrounding reservoir and secondly with what averaging or grouping technique should the core data be treated? It is to the description of successful measurement of vertical permeability that this paper is directed. During on in situ permeability testing program certain knowledge which will assist in subsequent tests within the same reservoir and also apply to other fields can be acquired. The success of such a testing program will reflect the cementing, initial and subsequent completions and stimulation history as well as the heterogeneities inherent to the reservoir in which the wells are located. In this paper, problems encountered during the testing of the five wells in the South Swan Hills Unit are dealt with in some detail. This should provide the reader with "experience factor" type background with which to pursue the design and execution of similar vertical permeability measurements. WELL SELECTION The five wells selected for vertical permeability tests in the South Swan Hills Unit were chosen to reflect a cross section of the reservoir.