Theory and Application of Imbibition Phenomena in Recovery of Oil

Abstract

The purpose of this paper is to present the results of theoretical and experimental studies of water imbibition. The imbibition processes are involved in recovery of oil from stratified and fractured-matrix formations in natural water drives and water flooding. An understanding of the role of imbibition in implementing the recovery of oil from such formations is deemed essential to proper control of these reservoirs to achieve maximum recovery. The theoretical studies involved development of the differential equations which describe the spontaneous imbibition of water by an oil-saturated rock. The dependence of the rate of water intake by the rock on the permeability, interfacial tension, contact angles, fluid viscosities and fluid saturations is discussed. A few experiments were performed using core samples to determine the effects of core length and presence of a free gas saturation. The role of water imbibition in recovery of oil from a fractured-matrix reservoir by water flooding was investigated by use of a laboratory model. This model was scaled to represent one element of a fractured-matrix formation. Water floods were made at various rates with several fracture widths. Interpretations were made of the behavior expected in a system containing many matrix blocks. The presence of a free gas saturation was found to reduce the rate of water imbibition. In the reservoir prototype of the fractured-matrix model, water imbibition rather than direct displacement by water was the dominant mechanism in the recovery of oil at low rates. Introduction Imbibition may be defined as the spontaneous taking up of a liquid by a porous solid. The spontaneous process of imbibition occurs when the fluid-filled solid is immersed or brought in contact with another fluid which preferentially wets the solid. In the process of wetting and flowing into the solid, the imbibing fluid displaces the non-wetting resident fluid. Common examples of this phenomenon are dry bricks soaking up water and expelling air, a blotter soaking up ink and expelling air and reservoir rock soaking up water and expelling oil.

CT measurements of two-phase flow in fractured porous media

“…(as opposed to "what did the authors conclude"). Graham and Richardson (1950) used a single block of fused quartz in their experiments. The block was in the shape of a right isosceles triangle.…”

Effect of shape factor, characteristic length, and boundary conditions on spontaneous imbibition

“…The rate of capillary imbibition (Moore and Slobod, 1956;Denekas et al, 1959;Handy, 1960) is mainly dependent on the properties of rock, the chemistry of the fluids, and the complex interactions between the rock and the fluids. The magnitude of oil recovery by capillary imbibition depends on pore geometry (Ma, 1992) and structure (Ma and Morrow, 1993) (matrix permeability), relative permeabilities (Li and Horne, 2001;Behbahani et al, 2006), interfacial tension (Graham and Richardson, 1959;Keijzer and de Vries, 1990;Schechter et al, 1991;Cuiec et al, 1994), liquid viscosities (Blair, 1964;Iffly et al, 1972;Ghedan and Poettmann, 1990;Cuiec et al, 1994;Ma et al, 1995b;Babadagli, 1996), size, shape, and boundary conditions of the matrix (Mattax and Kyte, 1962;Du Prey, 1978;Torsaeter and Silseth, 1985;Hamon and Vidal, 1986;Kazemi et al, 1992;Ma et al, 1995a;Zhang et al, 1995;Ma et al, 1997;Babadagli, 2001;Gokmen, 2003), and wettability (Graham and Richardson, 1959;Jadhunandan and Morrow, 1991;Ma et al, 1994;Morrow et al, 1994;Yildiz and Morrow, 1996;Tang and Morrow, 1997;Zhou et al, 2000).…”

“…Spontaneous imbibition is very important in oil recovery in porous media with special interest to the fluid flow behavior in fractured reservoirs (Aronofsky et al, 1958;Graham and Richardson, 1959;Warren and Root, 1963;Kazemi et al, 1976). Scaling of spontaneous imbibition data obtained at the laboratory scale conditions is of critical importance to give realistic estimate of oil recovery at the field scale (Zhang et al, 1995;Zhou et al, 1995).…”

Nonequilibrium Effects During Spontaneous Imbibition

“…Factors playing a role include rock and fluid properties, such as capillary pressure (Akin et al, 2000), wettability (Morrow, 1990;Kovscek et al, 1993), relative permeability, viscosity (Zhou et al, 2002), and interfacial tension (Graham and Richardson, 1959;Handy, 1960;Blair, 1964;Tong et al, 2001). The physics of imbibition are also strongly related to the Bond number Bo (= (ρ w − ρ nw )gk/σ ).…”