Abstract

MUNOZ, Oscar; ESCOBAR, Freddy  and  CANTILLO, José. CAPILLARITY AND RAPID FLOW EFFECTS ON GAS CONDENSATE WELL TESTS. C.T.F Cienc. Tecnol. Futuro [online]. 2006, vol.3, n.2, pp.73-82. ISSN 0122-5383.

The state-of-the-art of gas condensate well tests for pressures below the dewpoint are basically based upon a two-zone composite radial model, which consists of a near-wellbore region having liquid condensation and a monophasic flow zone with no gas condensate saturation. Information obtained from laboratory tests suggests the presence of three zones having different fluid mobilities: (1) a far region from the well with initial liquid condensate saturation of zero, (2) a near wellbore zone having an increased condensate saturation and a reduced gas mobility, and (3) an intermediate zone from the well with both high capillary and increasing gas relative permeability which leads to gas mobility restoring due to condensate blocking. The gas condensate saturation is higher than its critical value, then the condensate phase is mobile. In this study, both the rapid flow and capillary number effects on gas condensate reservoirs from well pressure test data are dealt with. We observed that the nondarcy effect originates additional pressure drop which is proportional to the flow rate while, the capillary number causes a reduction of condensate saturation in the near wellbore area and the reservoir providing a negative skin factor which contributes to fluid mobility, and therefore, production. Besides that, we also included the possitive coupled effect, defined here as the simoultaneous action of nondarcy flow and capillary number; which is more relevant at relatively low gas rates. We found out that the capillary number dominates the nondarcy effect leading to a reduction in condensate saturation.

Keywords : nondarcy flow; interfacial tension; capillary phenomenon; gas condensate reservoir.

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