Displacement fluid water

The pores between the rock components, e.g. the sand grains in a sandstone reservoir, will initially be filled with the pore water. The migrating hydrocarbons will displace the water and thus gradually fill the reservoir. For a reservoir to be effective, the pores need to be in communication to allow migration, and also need to allow flow towards the borehole once a well is drilled into the structure. The pore space is referred to as porosity in oil field terms. Permeability measures the ability of a rock to allow fluid flow through its pore system. A reservoir rock which has some porosity but too low a permeability to allow fluid flow is termed tight . 

Nearly all reservoirs are water bearing prior to hydrocarbon charge. As hydrocarbons migrate into a trap they displace the water from the reservoir, but not completely. Water remains trapped in small pore throats and pore spaces. In 1942 Arch/ e developed an equation describing the relationship between the electrical conductivity of reservoir rock and the properties of its pore system and pore fluids. 

Polymer flooding alms at reducing the amount of by-passed oil by increasing the viscosity of the displacing fluid, say water, and thereby improving the mobility ratio (M). 

Chemical processes work either to change the mobility of a displacing fluid like water, or to reduce the capillary trapping of oil in the rock matrix pores. Reducing the mobility of water, for example by adding polymers, helps to prevent fingering, in which the less viscous water bypasses the oil and... 

A recent application of this type of fluid is assistance in the removal of ingested salt spray from jet aircraft compressors and the neutralisation of corrosive effects. Other types of water-displacing fluids are claimed to have fingerprint neutralising properties or to be suitable for use on electrical equipment. Some oil-type materials serve temporarily as engine lubricants and contain suitable inhibitors to combat the corrosive products of combustion encountered in gasoline engines. 

Interpretation for irreducible water saturation assumes that the rock is water-wet or mixed-wet (water-wet during drainage but the pore surfaces contacted by oil becomes oil-wet upon imbibition). If a porous medium is water-wet and a nonwetting fluid displaces the water (drainage), then the non-wetting fluid will first occupy the larger pores and will enter the smaller pores only as the capillary pressure is increased. This process is similar to the accumulation of oil or gas in the pore space of a reservoir. Thus it is of interest to estimate the irreducible water saturation that is retained by capillarity after the hydrocarbon accumulates in an oil or gas reservoir. The FFI is an estimate of the amount of potential hydrocarbon in... 

Hot water injection via injection wells heats the soil and groundwater and enhances contaminant release. Hot water injection also displaces fluids (including LNAPL and DNAPL free product) and decreases contaminant viscosity in the subsurface to accelerate remediation through enhanced recovery. 

The displacing fluid may be steam, supercritical carbon dioxide, hydrocarbon miscible gases, nitrogen or solutions of surfactants or polymers instead of water. The VSE increases with lower mobility ratio values (253). A mobility ratio of 1.0 is considered optimum. The mobility of water is usually high relative to that of oil. Steam and oil-miscible gases such as supercritical carbon dioxide also exhibit even higher mobility ratios and consequent low volumetric sweep efficiencies. 

It is now well established through studies in many laboratories throughout the world that foam injection shows considerable promise as an agent for the improvement of oil recovery from watered-out. porous media, and for the diversion of the flow of other oil-displacing fluids from more permeable paths into less permeable paths in the medium<1). Whilst the reasons for the effectiveness of foam for these purposes are not. completely clear, the explanation is thought to lie in the behaviour of the foam lamellae... 

When a self-flushed pump is running, the space between the seal faces is filled with the seal flush fluid. When the pump is shut down, the space between the seal faces is filled with the fluid in the suction of the pump. However, if the pressure at the suction of the pump is below atmospheric pressure, then air is drawn through the seal faces and into the suction of the pump. This air displaces the water in the pump s case and, with time, causes the pump to lose its prime. 

EMCPMT models wifi be described that can simulate transient electro-mechano-chemo diffusion, convection, and osmosis in one-dimensional FEMs composed of one and/or multiple layers of porous material with prescribed no(Xi) and FCD, < [ (X,) in the solid. The left (L) and right (R) interfaces are water baths containing prescribed concentrations of up to three charged species (p, m, b). Mechanical force (stress) or displacement fluid pressure, and electrical potential will also be prescribed on these interfaces. The first example is... 

Figure 1.) The channeling can occur with either miscible or immiscible floods and results in much lower production of the displaced fluid for any given throughput of the injection fluid once the latter reaches the production well (10,12,15). The problem, which is common to water flooding and to all EOR processes, is most severe for gas flooding simply because it is in gas flooding that the injected fluids have the lowest viscosities (most unfavorable mobility ratios).

Ideally, the injected micellar solutions will be miscible with the fluids that they are in contact with in the reservoir and can thus miscibly displace those fluids. In turn, the micellar solutions may be miscibly displaced by water. Highest oil recovery will result if the injected micellar solution is miscible with the reservoir oil. If there are no interfaces, interfacial forces that trap oil will be absent. Injection of compositions lying above the multiphase boundary initially solubilizes both water and oil and displaces them in a misciblelike manner. However as injection of the micellar solution progresses, mixing occurs with the oil and brine at the flood front, and surfactant losses occur because of adsorption on the reservoir rock. These compositional changes move the system into the multiphase region. The ability of... 

During a waterflood, the injected water displaces the interstitial water as well as oil. There are two fluid boundaries one between the injected water and the interstitial water, and the other between the displaced interstitial water and the oil ahead. We want to find the water saturation at the boundary between the injected water and interstitial water. Because a nonadsorbing chemical travels at the same velocity as the water front, we can use Eq. 2.88 to find the water saturation at the front (the boundary between the injected and interstitial water), Swb- From Eq. 2.88, if Di is zero, we have... 

The existing concept of mobility control is that the displacing fluid mobility should be equal to or less than the (minimum) total mobility of displaced multiphase fluids. This chapter first uses a simulation approach to demonstrate that the existing concept is invalid the simulation results suggest that the displacing fluid mobility should be related to the displaced oil phase mobility, rather than the total mobility of the displaced fluids. From a stability point of view, a new criterion regarding the mobility control requirement is derived when one fluid displaces two mobile oil and water fluids. The chapter presents numerical verification and analyzes some published experimental data to justify the proposed criterion. 

When discussing viscous fingering, generaUy we deal with the case of displacing one mobile fluid (e.g., oil) by another fluid (e.g., water). The concept is that the displacing fluid mobility in the upstream (A,) should be equal to or less than the displaced fluid mobility in the downstream (A,[Pg.80]

In enhanced oil recovery processes, such as polymer flooding, one fluid (or even several fluids) displaces several mobile fluids (e.g., water and oil). According to the conventional concept, when one or several fluids displace several mobile fluids ahead, the total mobility of displacing fluids should be equal to or less than the total mobility of the several displaced fluids (Dyes et al., 1954 Lake, 1989) ... 

Our first task is to evaluate the validity of the conventional concept about the mobility control requirement using a simulation approach. This model uses the UTCHEM-9.0 simulator (2000). The dimensions of the two-dimensional XZ cross-section model are 300 ft x 1 ft x 10 ft. One injection well and one production well are at the two extreme ends in the X direction, and they are fully penetrated. The injection velocity is 1 ft/day the initial water saturation and oil saturation are 0.5. The displacing fluid is a polymer solution. The purpose of using the polymer solutuion in the model is to change the viscosity of the displacing fluid. Therefore, polymer adsorption, shear dilution effect, and so on are not included in the model. To simplify the problem, it is assumed that the oil and water densities are the same that the capillary pressure is not included that the relative permeabilities of water and oil are straight lines with the connate water saturation and residual oil saturation equal to 0 and that the water and oil viscosity is 1 mPa s. Under these assumptions and conditions, we can know the fluid mobilities at any saturation. The model uses an isotropic permeability of 10 mD. 

The water saturation distributions for the previous cases can further explain what would happen at different mobility ratios. The water saturation profile for Case viscOl at 0.5 PV injection is shown in Figure 4.6. Because the mobility ratio between the displacing fluid and displaced fluid is 1, the displacing front is stable. The finger is not further developed, and the displacing front is sharp. 

The conventional mobility ratio in multiphase flow is defined as the displacing fluid mobility divided by the total mobility of displaced water and oil phases. From the previous section, we can see that the unit mobility ratio based on the conventional definition is not a valid criterion to distinguish favorable and unfavorable mobility control conditions. We have found that a better criterion should be the unit mobility ratio, which is defined as the displacing fluid mobility divided by the oil mobility multiplied by the oil saturation (Eq. 4.9). In this section, we attempt to justify the proposed idea from the stability of displacement front. 

Figures 4.21 and 4.22 show the recovery factors versus M c and for the initial water saturation of 0.7. These figures show that the observations in the homogeneous model are still valid in the heterogeneous model. In other words, if we define the mobility ratio as the ratio of injection (displacing) fluid mobility to oil mobility multiplied by the normalized oil saturation, the unit mobility ratio is a much better criterion than the conventional one using the total mobility.

Wang et al. (2001c) performed polymer and ASP flooding tests after the cores were completely watered out. Increasing displacing fluid viscosity leads to a... 

This section discusses how to select the parameters to calculate capillary number. Initially, capillary number was proposed to correlate the residual saturation of the fluid (oil) displaced by another fluid (water) in the two-phase system. In surfactant-related flooding, there is multiphase flow (water, oil, and microemulsion), especially at the displacing front. If we use up/a to define the relationship between capillary number and residual oil saturation, which phase u and p and which o should be used then To the best of the author s knowledge, this issue has not been discussed in the literature. The following is what we propose. 

Note that the simulation results and simple frontal flow analysis show that the final oil recovery factor is similar even though a chemical flood is started at different initial oil saturations. However, more water is needed to displace the residual oil because it will be easier for the remaining oil to be trapped or bypassed by displacing fluids to lose oil phase continuity if the initial oil saturation is lower. Therefore, in reality, when a chemical flood is started at a higher oil saturation, a higher oil recovery factor is expected because the production will be stopped at an economic water cut. 

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