kuliahwet Pc share - DEFINITION OF INTERFACIAL TENSION Interfacial(boundary tension is the energy per unit area(force per unit distance at the surface

kuliahwet Pc share - DEFINITION OF INTERFACIAL TENSION...

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DEFINITION OF INTERFACIAL TENSIONInterfacial (boundary) tensionis the energy per unit area (force per unit distance) at the surface between phasesCommonly expressed as mN/m (also, dynes/cm)DEFINITION OF WETTABILITYWettabilityis the tendency of one fluid to spread on or adhere to a solid surface in the presence of other immiscible fluids.Wettability refers to interaction between fluid and solid phases.Reservoir rocks (sandstone, limestone, dolomite, etc.) are the solid surfaces Oil, water, and/or gas are the fluids WHY STUDY WETTABILITY?Understand physical and chemical interactions betweenIndividual fluids and reservoir rocksDifferent fluids with in a reservoirIndividual fluids and reservoir rocks when multiple fluids are presentPetroleum reservoirs commonly have 2 – 3 fluids (multiphase systems)When 2 or more fluids are present, there are at least 3 sets of forces acting on the fluids and affecting HC recovery
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DEFINITION OF ADHESION TENSIONAdhesion tensionis expressed as the difference between two solid-fluid. interfacial tensions.A positive adhesion tension indicates that the denser phase (water) preferentially wets the solid surface (and vice versa).An adhesion tension of zero indicates that both phases have equal affinity forthe solid surfaceWETTING PHASE FLUIDWetting phasefluid preferentially wets the solid rock surface.Attractive forces between rock and fluid draw the wetting phase into small pores.Wetting phase fluid often has low mobile.wowoswsoTAcos
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Attractive forces limit reduction in wetting phase saturation to an irreduciblevalue (irreducible wetting phase saturation).Many hydrocarbon reservoirs are either totally or partially water-wet.NONWETTING PHASE FLUID Nonwetting phasedoes not preferentially wet the solid rock surfaceRepulsive forces between rock and fluid cause nonwetting phase to occupy largest poresNonwetting phase fluid is often the most mobile fluid, especially at large nonwetting phase saturationsNatural gas is never the wetting phase in hydrocarbon reservoirsWATER-WET RESERVOIR ROCKReservoir rock is water - wet if water preferentially wets the rock surfacesThe rock is water- wet under the following conditions:so > swAT > 0 (i.e., the adhesion tension is positive)0<<90If is close to 0, the rock is considered to be “strongly water-wet”0<q<90Interfacial tension between the rock surface and water is less than between the rock surface and oil.SolidWaterOilsoswwo
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OIL-WET RESERVOIR ROCK90<q<180The interfacial tension between the rock surface and oil is less than between the rock surface and water.
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  • Fall '13
  • Surface tension, capillary pressure, Capillary pressure data

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