It operates in three basic modes: Sigma: water saturation detected via thermal neutron decay; C/O: oil saturation
detected with gamma spectroscopy; and water flow: water velocity from oxygen activation.
Based on many different experiments, some researchers have come to believe that viscous oil with a viscosity of below 100 mPa x s and an oil saturation
of above 30% is suitable for polymer flooding technique to enhance oil recovery (EOR); moreover, the permeability of the reservoir is above 20 x [10.sup.-3] [micro][m.sup.2], the thickness of the oil layers is above 3 m, and the temperature of the reservoir is under 90[degrees]C [16-20].
Figure 14 shows the oil saturation
distribution of the reservoir at the end of 15 years.
In addition, there are increasing laboratory and field evidences that the viscoelastic characteristics of polymer solutions help to improve microscopic sweep efficiency, resulting in lower residual oil saturation
where [P.sub.cave], [K.sub.ave], and [[phi].sub.ave] are average capillary pressure, permeability, and porosity of plugs under the same water saturation; [sigma] is interfacial tension; [theta] is wetting angle; [S.sub.wn] is normalized water saturation; [S.sub.w] is water saturation; [S.sub.wc] is connate water saturation; [S.sub.or] is irreducible oil saturation
As shown in Figure 1, curve A shows the cumulative distribution curve of the displacement efficiency at the time of taking out the core of the well, while curve B shows the cumulative probability distribution curve of the displacement efficiency under the residual oil saturation
. The mathematical expressions of the curves A and B are, respectively,
The alkali-surfactant-polymer (ASP) system can reduce both the mobility ratio and the IFT, so it can effectively reduce the remaining oil saturation
The numerical simulation results were carried out, the remaining oil saturation
were subtracted from the residual oil saturation
(Fu et al., 2010), and the residual oil reserves were calculated using the formula of reserves calculation (Fig.
Bahrain is considering the launch of a pilot project to recover a huge untapped resource in the residual oil saturation
in the Gas Cap of the Mauddud reservoir, Energy Minister Dr Abdul Hussain bin Ali Mirza said here at a conference.
Moreover, in the well located 100-140 m underground, the underlying aquifer will intercept part of shale oil and there is not enough oil leaking to the next aquifer through the high-permeability well fracture, thus resulting in the "disconnected" shale oil saturation
in the depleted wells.
Porosity, permeability and oil saturation
are three effective parameters in formation evaluation.