Reservoir dynamic

Maxiniizing the lvalue of the reservoir requires that full reservoir dynamics be considered in drilling wells and in extracting oil. Gas and water must be recycled through the strategic placement of injection wells wells with high gas-oil or water-oil ratios must be closed or not drilled and the rate of oil production must be controlled to maintain underground pressure. 

By modeling with SimSim original gas in place and reservoir dynamics was updated, clarified. 

As a first stage, SimSim was used to clarify reservoir dynamics. Results were then used later to build the detailed numerical model. The investigation performed with SimSim revealed the following important facts ... 

Zhang, Q. Lin, J. Pereira, S. Fluoroquinolone-resistant Campylobacter in animal reservoirs dynamics of development, resistance mechanisms and ecological fitness. Anim. Health Res. Rev. 2003, 4,... 

The timely acquisition of static and dynamic reservoir data is critical for the optimisation of development options and production operations. Reservoir data enables the description and quantification of fluid and rock properties. The amount and accuracy of the data available will determine the range of uncertainty associated with estimates made by the subsurface engineer. 

This section will look at formation and fluid data gathering before significant amounts of fluid have been produced hence describing how the static reservoir is sampled. Data gathered prior to production provides vital information, used to predict reservoir behaviour under dynamic conditions. Without this baseline data no meaningful reservoir simulation can be carried out. The other major benefit of data gathered at initial reservoir conditions is that pressure and fluid distribution are in equilibrium this is usuaily not the case once production commences. Data gathered at initial conditions is therefore not complicated... 

One method of sampling reservoir fluids and taking formation pressures under reservoir conditions in open hole is by using a wireline formation tester. A number of wireline logging companies provide such a tool under the names such as RFT (repeat formation tester) and FMT (formation multi tester), so called because they can take a series of pressure samples in the same logging run. A newer version of the tool is called a modular dynamic tester or MDT (Schlumberger tool), shown in Figure 3.8. 

Introduction and Commercial Application The reservoir and well behaviour under dynamic conditions are key parameters in determining what fraction of the hydrocarbons initially in place will be produced to surface over the lifetime of the field, at what rates they will be produced, and which unwanted fluids such as water are also produced. This behaviour will therefore dictate the revenue stream which the development will generate through sales of the hydrocarbons. The reservoir and well performance are linked to the surface development plan, and cannot be considered in isolation different subsurface development plans will demand different surface facilities. The prediction of reservoir and well behaviour are therefore crucial components of field development planning, as well as playing a major role in reservoir management during production. 

Reservoir simulation is a technique in which a computer-based mathematical representation of the reservoir is constructed and then used to predict its dynamic behaviour. The reservoir is gridded up into a number of grid blocks. The reservoir rock properties (porosity, saturation, and permeability), and the fluid properties (viscosity and the PVT properties) are specified for each grid block. 

Introduction and Commercial Application Section 8.0 considered the dynamic behaviour in the reservoir, away from the influence of the wells. However, when the fluid flow comes under the influence of the pressure drop near the wellbore, the displacement may be altered by the local pressure distribution, giving rise to coning or cusping. These effects may encourage the production of unwanted fluids (e.g. water or gas instead of oil), and must be understood so that their negative input can be minimised. 

At the development planning stage, a reservoir mode/will have been constructed and used to determine the optimum method of recovering the hydrocarbons from the reservoir. The criteria for the optimum solution will most likely have been based on profitability and safety. The model Is Initially based upon a limited data set (perhaps a seismic survey, and say five exploration and appraisal wells) and will therefore be an approximation of the true description of the field. As development drilling and production commence, further data is collected and used to update both the geological model (the description of the structure, environment of deposition, diagenesis and fluid distribution) and the reservoir model (the description of the reservoir under dynamic conditions). 

A second approach, due originally to Nos e [ ] and refomuilated in a usefiil way by Hoover [M], is to introduce an extra thennal reservoir variable into the dynamical equations ... 

Another development arising from FAB has been its transformation from a static to a dynamic technique, with a continuous flow of a solution traveling from a reservoir through a capillary to the probe tip. Samples are injected either directly or through a liquid chromatography (LC) column. The technique is known as dynamic or continuous flow FAB/LSIMS and provides a convenient direct LC/MS coupling for the on-line analysis of mixtures (Figure 40.2). 

Another popular approach to the isothennal (canonical) MD method was shown by Nose [25]. This method for treating the dynamics of a system in contact with a thennal reservoir is to include a degree of freedom that represents that reservoir, so that one can perform deterministic MD at constant temperature by refonnulating the Lagrangian equations of motion for this extended system. We can describe the Nose approach as an illustration of an extended Lagrangian method. Energy is allowed to flow dynamically from the reservoir to the system and back the reservoir has a certain thermal inertia associated with it. However, it is now more common to use the Nose scheme in the implementation of Hoover [26]. 

The main problem of elementary chemical reaction dynamics is to find the rate constant of the transition in the reaction complex interacting with its environment. This problem, in principle, is close to the general problem of statistical mechanics of irreversible processes (see, e.g., Blum [1981], Kubo et al. [1985]) about the relaxation of initially nonequilibrium state of a particle in the presence of a reservoir (heat bath). If the particle is coupled to the reservoir weakly enough, then the properties of the latter are fully determined by the spectral characteristics of its susceptibility coefficients. 

The dynamics of these models depend strictly on carbon fluxes, but the fluxes are poorly measured or are calculated from carbon reservoir size and assumptions about the residence time of the carbon in the reservoir. In addition, model fluxes are linear functions while in reality few, if any, probably are linear. 

As an illustration of the concept introduced above, let us consider a coupled two-reservoir system with no external forcing (Fig. 4-6). The dynamic behavior of this system is governed by the two differential equations... 

An investigation of the dynamic behavior of a coupled three-reservoir system using the techniques described above is included in the problems listed at the end of the chapter. 

Before turning to nonlinear situations, let us consider two specific examples of coupled linear systems. The first describes the dynamic behavior of a multireservoir system the second represents a steady-state situation of an open two-reservoir system. 

For the more mathematically inclined Investigate the dynamic behavior of a coupled linear three reservoir model using the technique outlined in Section 4.3.1. 

It is now widely accepted that the compositions of the atmosphere and world ocean are dynamically controlled. The atmosphere and the ocean are nearly homogeneous with respect to most major chemical constituents. Each can be viewed as a reservoir for which processes add material, remove material, and alter the compositions of substances internally. The history of the relative rates of these processes determines the concentrations of substances within a reservoir and the rate at which concentrations change. Commonly, only a few processes predominate in determining the flux of a substance between reservoirs. In turn, particular features of a predominant process are often critical in controlling the flux of a phase through that process. These are rate-controlling steps. 

Obviously, these examples do not cover all possible management options, but they highlight the fact that a sound knowledge of the hydrodynamics is of paramount importance for a proper water quality oriented management. Reservoirs are very dynamic systems that often stratify in a multilayered fashion to produce layers of water with huge differences in their residence time [60]. In impaired reservoirs, the best option is to increase residence time of anoxic layers, and reduce it for surface water. The presence of outlets at different depths is essential in reservoirs devoted to water supply. 

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