Oil Displacement for One-Dimensional Three-Phase Flow with Phase Change in Fractured Media

Abstract

In this article, the numerical simulations for one-dimensional three-phase flows in fractured porous media are implemented. The simulation results show that oil displacement in matrix is dominated by oil-water capillary pressure only under certain conditions. When conditions are changed to decrease the amount of water entering into the fractured media from the boundary of the flow field, water in fracture may be vaporized to superheated steam. In these cases, the appearance of superheated steam in fracture rather than in matrix will decrease the fracture pressure and generate the pressure difference between matrix and fracture, which results in oil flowing from matrix to fracture. Assuming that oil is wetting to steam, the matrix steam-oil capillary pressure will decrease the matrix oil-phase pressure as the matrix steam saturation increases. After the steam-oil capillary pressure finally exceeds the pressure difference due to the appearance of superheated steam in fracture, the oil displacement in matrix will stop. It is also shown that variations of the water relative permeability curve in matrix do not result in different mechanisms for oil displacement in matrix. The simulation results suggest that the amount of liquid water supply from the boundary of flow field fundamentally influence the mechanisms for oil displacement in matrix.Keywords Fluid flows in porous media · Multi-phase flows · Fractured media · Steam injection · Oil recovery Nomenclature C Pα α-Phase isobaric specific heat (J/kg • C) E Exchange of energy between fracture and matrix (J/m 3 s) K Intrinsic permeability (m 2 ) K rα α-Phase relative permeability K rog

How to Improve our Understanding of Gas and Oil Production Mechanisms in Liquid-rich Shale

“…This is because oil and gas will leave water-wet inorganic matter (with a higher gas and organic phase pressure) towards low pressure fracture network. At later times, when pressure depletes in the matrix, aqueous phase pressure in the water-wet inorganic matter falls below the fracture pressure, resulting in a counter current water imbibition from fracture into the matrix, which has additional benefits of displacing hydrocarbon from the matrix, as mentioned by many researchers such as Luo and Wang (2009). Water movement into the inorganic matrix will not be very effective during the early imbibition stages due to its low relative permeability at initial water saturations.…”

Entrapment of the Non-wetting Phase during Co-current Spontaneous Imbibition

“…Many research groups are currently active in various aspects of spontaneous imbibition by experiments 7 and numerical modeling. 8 The specific items include the nature of the imbibition front, 9 the capillary back pressure at the open face, 10 the capillary pressure at the imbibition front, 3,11 the initial water saturation, 12 geometric shape of the core sample, 13 rock type, 14 and wetting phase and non-wetting phase viscosity. 15 Much insight can be gained from the studies of the simplest systems, such as the tube models.…”

“…Understanding the mechanism of spontaneous imbibition is significant for the recovery of the fractured reservoirs. Many research groups are currently active in various aspects of spontaneous imbibition by experiments and numerical modeling . The specific items include the nature of the imbibition front, the capillary back pressure at the open face, the capillary pressure at the imbibition front, , the initial water saturation, geometric shape of the core sample, rock type, and wetting phase and non-wetting phase viscosity …”