Recovery factor calculation

Recovery factor calculations may not be possible under certain situations, including (1) a decrease in steam flow rate due to water breakthrough (2) scale deposits in the well-bore and/or fracture conduits (3) a fluctuating flow rate and (4) the completion of additional production wells in injection-affected areas, which will have an impact on the decline rates of nearby production wells. 

Thus, the application of in situ combustion made it piossible to nearly double the output rate. Already towards the end of the second year of the thermal treatment, the total oil output from the reservoir exceeded the ultimate recovery calculated for production by natural drive(s) at depletion rates. The current recovery factor with the themal treatment was 2.35 times greater than the maximum recovery factor calculated for production by natural reservoir drive. At the end of 1980, the current production level equalled 1501 of oil per month. 

For the cost of local pipelines the total length must be considered, so the average length of each local pipeline must be multiplied by the number of local pipelines to determine the total capital cost. The total capital cost of the pipeline and the compressors are then annualized using the pipeline capital recovery factor, calculated in the model. 

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. 

Analytical models using classical reservoir engineering techniques such as material balance, aquifer modelling and displacement calculations can be used in combination with field and laboratory data to estimate recovery factors for specific situations. These methods are most applicable when there is limited data, time and resources, and would be sufficient for most exploration and early appraisal decisions. However, when the development planning stage is reached, it is becoming common practice to build a reservoir simulation model, which allows more sensitivities to be considered in a shorter time frame. The typical sorts of questions addressed by reservoir simulations are listed in Section 8.5. 

When estimating the recovery factor, it is important to remember that a range of estimates should be provided as input to the calculation of ultimate recovery, to reflect the uncertainty in the value. 

The type of development, type and number of development wells, recovery factor and production profile are all inter-linked. Their dependency may be estimated using the above approach, but lends itself to the techniques of reservoir simulation introduced in Section 8.4. There is never an obvious single development plan for a field, and the optimum plan also involves the cost of the surface facilities required. The decision as to which development plan is the best is usually based on the economic criterion of profitability. Figure 9.1 represents a series of calculations, aimed at determining the optimum development plan (the one with the highest net present value, as defined in Section 13). 

This is then converted to annualized capital costs (ACC) with the use of the capital recovery factor (CRF), which can be calculated from the following equation ... 

The CCE spreads the investment over the lifetime of the measure into equal annual payments with the familiar capital recovery factor. The annual payment is then divided by the annual energy savings to yield a cost of saving a unit of energy. It is calculated using the following formula ... 

The definitions above are an abbreviated version of those used in a veiy complex and financially significant exercise with the ultimate goal of estimating resei ves and generating production forecasts in the petroleum industry. Deterministic estimates are derived largely from pore volume calculations to determine volumes of either oil nr gas in-place (OIP, GIP). This volume when multiplied by a recovery factor gives a recoverable quantity of oil or natural gas liquids—commonly oil in standard barrels or natural gas in standard cubic feet at surface conditions. Many prefer to use barrels of oil equivalency (BOE) or total hydrocarbons tor the sum of natural gas, natural gas liquids (NGL), and oil. For comparison purposes 6,000 cubic feet of gas is considered to be equivalent to one standard barrel on a British thermal unit (Btu) basis (42 U.S. gallons). 

The recovery factor is defined as the ratio of additional steam provided by injection to the amount of water injected over the same period of time. Additional steam is the steam produced at the new decline rate (or improvement rate) due to injection minus the steam production calculated at a decline rate without re-injection. The recovery factor defined on the basis of production data may be different from that defined on the basis of geochemical data if considered on a well-by-well basis. However, the combined recovery from all production wells affected by one or more injection wells should agree when applying both methods given sufficient time, since (1) the total amount of boil water should appear as steam in production wells and be reflected in the production data, and (2) the steam originally to be produced from a given well but replaced by injection-derived steam should eventually be produced in other wells. 

Step 4. Calculate the percent of analyte extracted into the organic solvent at equilibrium. The recovery factor, Rx, is the fraction of the analyte extracted divided by the total concentration of the analyte, multiplied by 100 to give the percentage recovery ... 

We must consider the laminar and turbulent portions of the boundary layer separately because the recovery factors, and hence the adiabatic wall temperatures, used to establish the heat flow will be different for each flow regime. It turns out that the difference is rather small in this problem, but we shall follow a procedure which would be used if the difference were appreciable, so that the general method of solution may be indicated. The free-stream acoustic velocity is calculated from... 

When free-molecule flow is encountered, Oppenheim [8] has given convenient charts for calculating recovery factors and heat-transfer coefficients for flow over standard geometric shapes. Figures 12-16 and 12-17 give samples of these charts. The molecular speed ratio S used in these charts is defined by... 

Example 2 Determination of percentage factors as given for Modified Accelerated Cost Recovery System. Calculate the percentage factors for a class life of 10 years as presented in Table 4 of this chapter for the Modified Accelerated Cost... 

Calculate the capital recovery factor. In this method, each of the undiscounted net cash flows (NCFs) for years 1 to 20 is algebraically added to the capital recovery cost (CRC) to obtain the equivalent uniform annual revenue (EUAR). The CRC is the product of the total capital investment,... 

TCI, and the capital recovery factor, CRF, which is defined and calculated by Eq. (18.7) of the introduction. The project with the higher EUAR will be the one to fund. The pertinent input data are as follows ... 

Determine the EUAR for each option, assuming a 6% hurdle rate. Following the procedure of Example 18.7, calculate for each option the undiscounted net cash flow, the capital recovery factor, the capital recovery cost, and the EUAR. The results are as follows ... 

Figure 23-9 is a set of curves, calculated from (23-19) and (23-23), for enrichment factor [Equation (22-2)] as a function of the number of equilibrations and transfers under several conditions. The number of equilibrations and transfers for quantitative recovery (recovery factor = 0.999) of component A and for its quantitative separation (enrichment factor = 0.001) from component B is indicated by the intersections of the lines with the 0.001 line for termination at the upper edge of the curves... 

The result (3.355) was only valid under the precondition that the Prandtl number of a gas which is presumed to be ideal is Pr = 1. In the general case of flow of an ideal gas with a Prandtl number Pr 1, a different eigentemperature is present which is still dependent on the Prandtl number. In order to calculate this the so-called Recovery Factor r is introduced. It is defined by... 

The annual operation costs of an outdated environmental control device is 75,000. Under a proposed emission reduction plan, the installation of a new processing system will require an initial cost of 150,000 and an annual operating cost of 15,000 for the first 5 years. Determine the annualized cost for the new processing system by assuming the system has only 5 years (n) operational life. The interest rate (0 is 7%. The capital recovery factor (CRF) or annual payment of a capital investment can be calculated as follows ... 

The produced water had some polymer. The produced water may be injected before or after the main polymer slug as preflush or postflush slugs. A calculation showed that 2.5% incremental oil recovery could be obtained if the produced water was injected as preflush and 0.9% as postflush. A laboratory test showed that if the produced water had 400 mg/L polymer (with solution viscosity of 2.5 mPa s), the incremental oil recovery factor was about 3% (Zhang, 1998). 

Organic carbon value considering recovery factor of 0.77 can be calculated using the formula. 

In Ref. 46, an ingenious set of transformations is employed to evaluate the recovery factor away from the stagnation line. The results for PP = 1 show a significant departure (= -10 percent for Pr = 0.7) from r(0) = Pr1 2. These values, however, do not agree with calculations performed in Ref. 49. Perhaps the discrepancy is due to the evaluation of r(0) in Ref. 46 by taking the derivative of a function. Slight errors in the function itself could easily account for a 10 percent error in the derivative. For accuracies of r(0) within a few percent [48], it is recommended that... 

A template for calculating cost of electricity has been developed. The analysis considers efficiency, capital costs, operating and maintenance costs, capital recovery factor, availability, fuel price and other factors. A detailed economic analysis will be performed. 

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