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This study analyses the effects of nongray gas radiation on double diffusive convection, in a square differentially heated cavity filled with air-CO 2 mixtures, when the buoyancy forces (thermal and mass) are cooperating or opposing. The radiative source term in the energy equation is evaluated by the discrete ordinate method (solving the radiative transfer equation) and the SLW spectral model (accounting for real radiative properties of absorbing species). Here, gas absorption varies with the local temperature and concentration of pollutant, which induces a strong direct coupling between the concentration and thermal fields that would not exist with gray gas. Simulations are performed at different concentrations of CO 2 corresponding to different flow regimes (thermal, transitional, and mass). Results show the following: (i) in cooperating flow, radiation modifies essentially the heat transfer and the characteristics of temperature and concentration fields; (ii) in opposing flow, radiation effects are more important and depend on the nature of the flow regime.

It is often desirable to know patterns created after a number of wells in reservoir have been fractured. Interference testing is one of the best techniques that can be used for estimating some of the important formation properties (transmissibility and storativity) and fracture orientation. Generalized correlations are presented relating (a) the dimensionless pressure response, PD, inter, at the intersection point of the pressure and the pressure derivative to the compass orientation, ?, and (b) the quotient of the dimensionless pressure and the ratio of dimensionless time to the square of the dimensionless radial distance, (tDrD2)inter, at the intersection point to the compass orientation. The correlations can be used for analyzing interference test pressure response at an unfractured shut-in well caused by a production of a vertically fractured well with a uniform flux, infinite or finite conductivity fracture provided that the half fracture length is known a priori. Detailed procedures for the analysis of interference testing of a vertically fractured well are presented and demostrated through a simulated example. Introduction The data required to select the better reservoir management method include inter-well properties, the degree of communication between different wells, and information about the reservoir heterogeneity. Pressure transient testing techniques, such as pressure drawdown, build-up, injectivity, falloff, and interference are some of the most frequently used methods in reservoir and production engineering for obtaining these data. Practical information obtainable from these techniques includes amount of wellbore damage or stimulation, formation permeability, porosity, reservoir, and fluid discontinuities, and other related data. In certain situations, pressure transient testing is indispensable for reservoir analysis; for example, in definition of near-wellbore and inter-well conditions. In other cases, even with the most complex and through transient analysis, a unique solution often is not possible without considering other information such as production logs, stimulation history, core descriptions. Interference test and pulse tests are best suited for obtaining inter-well properties. Interference comes from the fact that the pressure drop caused by the producing well or wells at the shut-in observation well interferes with the pressure at the observation well or wells. Therefore, interference test is a multiple-well-test, which requires at least one active well and at least one observation well. The active well is either a producer or injector and the observation wells are shut-in wells in which pressure effects caused by the active well are measured. Multiple well tests are more sensitive to reservoir heterogeneity than single well tests and give information on reservoir properties than cannot be obtained from ordinary well tests, for instance, the orientation of the hydraulically vertical fractures, the orientation of the maximum and minimum permeabilities. Tongpenyai and Raghavan1 have presented solutions that can be used to analyze interference test data influenced by wellbore storage and skin effect at both the active and the observation well. Several studies have considered the effect of vertical fractures on transient pressure behavior of wells2. It was recognized that single well tests and interference testing could be used to determine properties of vertical fractures such as fracture length and fracture orientation respectively. In 1973, Gringarten and Ramey3 prepared tables of instantaneous Green's and source functions, which can be used with the Newman's product method to generate solutions for a wide variety of reservoir flow problems. This approach has been applied in the efforts to formulate analytical solutions to flow equations in fractured reservoirs.

A numerical study is performed to investigate the effect of the adiabatic walls emissivity on coupled double diffusive natural convection and gas radiation in a differentially heated square enclosure filled with non-gray air-H2O mixtures in a cooperating case. The vertical walls of the enclosure are maintained at two different but uniform temperatures. The remaining boundaries are thermally insulated and considered as adiabatic walls. These walls are assumed to be opaque, diffuse and gray. Their emissivity is variable (ε=0, 0.1, 0.5 and 1). The governing differential equations are solved by a finite-volume method and the SIMPLE algorithm was adopted to solve the pressure-velocity coupling. The discrete ordinates method (DOM) associated with the spectral line weighted-sum-of-graygases (SLW) is used to solve the radiative transfer equation. Simulations are performed in configurations where thermal and concentration gradient induces cooperating buoyancy forces. Results obtained for three average molar fractions of H 2 O (5%, 10% and 20%). The effects of walls emissivity on the flow and temperature fields and heat transfer rates are analyzed.

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