Material Balance Calculations

Gas reservoirs are produced by expansion of the gas contained in the reservoir. The high compressibility of the gas relative to the water in the reservoir (either connate water or underlying aquifer) make the gas expansion the dominant drive mechanism. Relative to oil reservoirs, the material balance calculation for gas reservoirs is rather simple. A major challenge in gas field development is to ensure a long sustainable plateau (typically 10 years) to attain a good sales price for the gas the customer usually requires a reliable supply of gas at an agreed rate over many years. The recovery factor for gas reservoirs depends upon how low the abandonment pressure can be reduced, which is why compression facilities are often provided on surface. Typical recovery factors are In the range 50 to 80 percent. 

The primary drive mechanism for gas field production is the expansion of the gas contained in the reservoir. Relative to oil reservoirs, the material balance calculations for gas reservoirs is rather simple the recovery factor is linked to the drop in reservoir pressure in an almost linear manner. The non-linearity is due to the changing z-factor (introduced in Section 5.2.4) as the pressure drops. A plot of (P/ z) against the recovery factor is linear if aquifer influx and pore compaction are negligible. The material balance may therefore be represented by the following plot (often called the P over z plot). 

The subscript i refers to the initial pressure, and the subscript ab refers to the abandonment pressure the pressure at which the reservoir can no longer produce gas to the surface. If the abandonment conditions can be predicted, then an estimate of the recovery factor can be made from the plot. Gp is the cumulative gas produced, and G is the gas initially In place (GIIP). This is an example of the use of PVT properties and reservoir pressure data being used in a material balance calculation as a predictive tool. 

Reservoir pressure is measured in selected wells using either permanent or nonpermanent bottom hole pressure gauges or wireline tools in new wells (RFT, MDT, see Section 5.3.5) to determine the profile of the pressure depletion in the reservoir. The pressures indicate the continuity of the reservoir, and the connectivity of sand layers and are used in material balance calculations and in the reservoir simulation model to confirm the volume of the fluids in the reservoir and the natural influx of water from the aquifer. The following example shows an RFT pressure plot from a development well in a field which has been producing for some time. 

Only parts needed above but for the vapor-phase reactor are listed here. Most of the description for the installation for methanol synthesis experiments (Figure 4.2.1) holds for this installation, too. In the mentioned unit, product was blown down while still hot, thus keeping all product in a single vapor phase. This simplifies material balance calculations. When avoiding condensation is difficult, cooling and separation becomes necessary. This method was used in the cited AIChEJ publication. 

Generally, these concentrations are expressed in terms of moles of solute per mole of pure solvent (liquid phase) and moles of solute per mole of inert gas (gas phase), thus making the material balance calculations easier. 

When relevant monitoring data or emission measurements are not readily available, reasonable estimates of the amounts released must be made using published emission factors, material balance calculations, or engineering calculations. You may not use emission factors or calculations to estimate releases if more accurate data are available. 

In summary, the procedure to be adopted in material balance calculations involving reactive systems is as follows ... 

Davison Div., W.R. Grace Co., Cat Cracker Heat and Material Balance Calculations, Grace Davison Catalagram, No. 59, 1980. 

Any process can be divided up in an arbitrary way to facilitate the material balance calculations. The judicious choice of the system boundaries can often greatly simplify what would otherwise be difficult and tortuous calculations. 

Material balance calculations on processes with by-pass streams are similar to those involving recycle, except that the stream is fed forward instead of backward. This usually makes the calculations easier than with recycle. 

This example illustrates the use of phase equilibrium relationships (vapour-liquid) in material balance calculations. 

This example illustrates the use of liquid-liquid phase equilibria in material balance calculations. The condensate stream from the condenser described in Example 4.2 is fed to a decanter to separate the condensed water and dichloroethane (EDC). Calculate the decanter outlet stream compositions. 

Distribution planning covers transportation and inventory planning within the network, as well as the material balance calculation between sales, production and procurement. Global transportation planning considers the lead times between continents resulting in transit inventories differentiation of sent and received transportation quantities as shown in the requirements in section 4.1.5. Inventories are managed at the defined transfer point locations either with static or dynamic boundaries. 

Chou and Wollast (23) challenged XPS studies which indicate that incongruent surface layers thicker than several Angstroms do not exist. They argue that material balance calculations require some sort of altered layer in order to account for the observed incongruency between alkalis, silica, and aluminum. Their material balance calculations suggest that the layer thickness must be on the order of only tens of nanometers, which, despite their arguments to the contrary, is not inconsistent with the surface chemistry observations (e.g., XPS) they seek to refute. 

An expert, given time to do so, may utilize calculations to develop inference results. For example, a material balance calculation around a process unit may indicate a measurement inconsistency. To mimic this expertise, general mathematical operations on combinations of measurements or functions of measurements are implemented in the parallel processor also. 

We now turn to black oils. We consider those physical properties which are required for the reservoir engineering calculations known as material balance calculations. These properties are formation volume factor of oil, solution gas-oil ratio, total formation volume factor, coefficient of isothermal compressibility, and oil viscosity. Also, interfa-cial tension is discussed. 

Formation volume factors and solution gas-oil ratios normally are not measured for volatile oils. These quantities are used primarily in material balance calculations which do not apply to volatile oils. If these quantities were measured for volatile oils, they would have the shapes indicated in Figures 8-10 and 8-11. The large decreases in both curves... 

Volatile oil reservoirs are engineered through compositional material balance calculations. A special laboratory study (not discussed in this text) is required. 

A black oil reservoir fluid study consists of a series of laboratory procedures designed to provide values of the physical properties required in the calculation method known as material balance calculations. There are five main procedures in the black oil reservoir fluid study. These procedures are performed with samples of reservoir liquid. 

In addition to the 1 4 ratio of the e—e and ee peak areas, there are a number of other quantitative relationships between resonance areas. For example, there must always be a 1 2 relationship between the areas of the e—m and em peaks. Furthermore, material-balance calculations must agree with the peak assignments. These requirements, in addition to the ones discussed in the previous paragraph, lead to an unambiguous structural assignment of the NMR spectra and thus a correct mathematical description of the system. 

Linear. Since mass and energy are linearly related between modules, purely linear flowsheet calculations can be formulated as a solution to a set of linear equations once linear models for the modules can be constructed. Linear systems, especially for material balance calculations can be very useful (16). Two general systems, based on linear models, SYMBOL (77) and MPB II (7 ) are indicated in Table 1. MPB II is based on a thesis by Kniele (79). If Y is the vector of stream outputs and the module stream inputs are X, then as discussed by Mahalec, Kluzik and Evans (80)... 

Phenone is produced by the acetylation of benzyl chloride with o-xylene via a Friedel-Crafts reaction. Table 1.1 presents the elements of the material balance. Calculate the efficiency of raw materials. 

The decalins recovered in the product were present in the tetralin before reaction as minor impurities. The cis- and trans-isomers were fully resolved in our chromatograms and positively identified by spiking experiments with authentic samples. Material balance calculations indicate that the total amount of decalins was essentially unchanged over the course of the reaction. Hooper et al. (10) have also reported that the amount of decalin in tetralin did not change when it was heated to 450°C with coal. However, we do observe that the ratio of the trans- to cis-isomer is greatly changed and seems to approach an equilibrium value after reaction at the highest coal concentration. 

The overhead composition is stipulated to be 99.8% benzene and 0.2% toluene. By material-balance calculation, the bottoms is found to be 2.6% benzene and 97.4% toluene. 

Material-balance calculations (see Section 2) indicate that the withdrawal rate for overhead product from the system is 7.38 mol/h therefore, 73.8 mol/h must be refluxed, and the vapor flow from the top of the column must be 73.8 + 7.38 = 81.18 mol/h. The vapor consists of almost pure ECH, whose molecular weight is 112, so mass flow from the top is 81.18(112) = 9092 lb/h (4133 kg/h). The bottoms stream is 2.62 mol/h. 

MATERIAL-BALANCE CALCULATIONS FOR CLOSED-CIRCUIT GRINDING 13.6... 

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