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

kuliahwet Pc - DEFINITION OF INTERFACIAL TENSION...

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DEFINITION OF INTERFACIAL TENSION Interfacial (boundary) tension is the energy per unit area (force per unit distance) at the surface between phases Commonly expressed as mN/m (also, dynes/cm) DEFINITION OF WETTABILITY Wettability is 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 between Individual fluids and reservoir rocks Different fluids with in a reservoir Individual fluids and reservoir rocks when multiple fluids are present Petroleum 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 TENSION Adhesion tension is 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 for the solid surface WETTING PHASE FLUID Wetting phase fluid 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. wo wo sw so T A cos
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NONWETTING PHASE FLUID Nonwetting phase does not preferentially wet the solid rock surface Repulsive forces between rock and fluid cause nonwetting phase to occupy largest pores Nonwetting phase fluid is often the most mobile fluid, especially at large nonwetting phase saturations Natural gas is never the wetting phase in hydrocarbon reservoirs WATER-WET RESERVOIR ROCK Reservoir rock is water - wet if water preferentially wets the rock surfaces The rock is water- wet under the following conditions: so > sw AT > 0 (i.e., the adhesion tension is positive) 0 < < 90 If is close to 0 , the rock is considered to be “strongly water-wet” 0 < q < 90 Interfacial tension between the rock surface and water is less than between the rock surface and oil. Solid Water Oi l so sw wo
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OIL-WET RESERVOIR ROCK 90 < q < 180 The interfacial tension between the rock surface and oil is less than between the rock surface and water. WATER-WET OIL-WET Solid Water Oil wo Ayers, 2001 FREE WATER GRAIN SOLID (ROCK) WATER OIL SOLID (ROCK) WATER OIL GRAIN BOUND WATER F R E E W A T E R OIL OIL RIM < 90 > 90 WATER Oi l Ai r WATER
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WETTABILITY IS AFFECTED BY: Composition of pore-lining minerals Composition of the fluids Saturation history (hysteresis effects
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  • Fall '13
  • Surface tension, capillary pressure, Capillary pressure data

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