Reservoir processes

Eig. 1. Generalized cycle of the various reservoirs and transport mechanisms and pathways involved in the circulation of nutrient elements. The numbered arrows represent processes by which elements transfer among the reservoirs. Processes shown are those considered to have the most important influence... 

Cooper K.M. and Reid M.R. (2003) Reexamination of crystal ages in recent Mount St. Helens lavas implications for magma reservoir processes. Earth Planet Set. Lett. 213, 149-167. 

Recently, use of a surfactant in the injected water such that a foam or emulsion is formed with carbon dioxide has been proposed (20.21) and research is proceeding on finding appropriate surfactants (22-24). The use of such a foam or emulsion offers the possibility of providing mobility control combined with amelioration of the density difference, a combination which should yield improved oil recovery. Laboratory studies at the University of Houston (25) with the same five-spot bead-pack model as used before show that this is so, for both the relatively water-wet and relatively oil-wet condition. We have now simulated, with a finite-difference reservoir process computer program, the laboratory model results under non-WA3, WAG, and foam displacement conditions for both secondary and tertiary recovery processes. This paper presents the results of that work. 

The terms EOR and lOR should refer to reservoir processes. Any practices that are independent of the recovery process itself should not be grouped into either EOR or lOR. Such practices include reservoir characterization, reservoir simulation, use of hardware and equipment (pumps, down-hole separators, etc.), use of special well types (horizontal wells, multilaterals, smart wells, etc.), improved reservoir management, infill drilling, and so on. Oil here means hydrocarbon, including oil and natural gas. 

Improved oil recovery refers to any reservoir process to improve oil recovery. Virtually, this term comprises all but the primary processes (Stosur et al., 2003). The following is an incomplete list ... 

Abercrombie, H.J. (1991) Reservoir processes in steam-assisted recovery of bitumen, Lemin Pilot, Cold Lake, Alberta, Canada composition, mixing and sources of co-produced waters. Appl. Geochem., 6, 495-508. 

Meulbroek et al. have created an innovative computational framework to estimate phase equilibria, equation of state properties and compositionally dependent viscosity for the modelling of reservoir processes. This toolkit has been designed with the reservoir geochemist in mind and therefore is created as a set of modules that can be utilized within standard spreadsheet applications. 

Oil or water chemistry can be determined from fluid samples or from core extracts. Oil or gas variations may be inherited from the filling history, or be modified by in-reservoir processes such as described above for density. Water variations relate to either water-rock interaction (e.g. dissolution of salt or feldspars), or to regional flow patterns (e.g. influx of meteoric water). 

Figure 5 illustrates the conventional diagram normally used for oil-water-alcohol (or surfactant) processes. For CO2 or hydrocarbon-miscible processes, authors conventionally rotate the ternary diagram 120° clockwise, but the illustrated principle is the same. The binodal curve is normally higher for alcohol and lower for surfactants than the curve shown in Figure 5. Although no real reservoir process can be completely miscible in the exact...

Whilst in the HCl form it is inactive towards ozone, and therefore this sequence of reactions acts as a holding mechanism, delaying the release of Cl, rather than necessarily actually permanently removing it from the mix. It is thought that as much as 70 % of stratospheric Cl is held in this form. Other reservoir processes trap CIO, which temporarily forms HOCl and CIONO2, in the reactions ... 

For a more transparent interpretation of irreversible processes, consider an entropy transfer from the reservoir to the system the examination of the opposite case is left as an exercise. We rewrite Eq. (1.9.1c) in the form dS T, V, tii) — dbSo To, Vq, noO — d0 = 0, or as dS T, V, rii) = Idb-SoCTo, Vo, oi) + d, with 7b > T. This shows that the total entropy increase of the system (the left-hand side) consists of what is reversibly transferred out of the reservoir (recall the assumption that all reservoir processes are executed reversibly) plus what is irreversibly generated internally by the release of constraints. The latter events are beyond the control of the experimenter and are not transferred across the boimdaries of the system. It is only when no such processes take place that the entropy increase in the system is matched by the corresponding entropy decrease in the surroundings at the common temperature T. 

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