Mysore G. Satish

Knowledge Selection for Laser Drilling in the Oil and Gas Industry

To maximize oil and gas production profitability, it is paramount to reach the whole reservoir and extract the oil and gas in it efficiently. Therefore the well should be drilled as quickly as possible to start production as soon as possible. The laser drilling literature reviews, lab experiments, and numerical models have proven so far that this novel technique performs better and faster than the conventional rotary drilling technique. In addition, this eliminates the problem of contaminated water, soil, and rocks due to the use of toxic muds while rotary drilling. As a result, the drilling and production operations costs are minimized. This paper introduces the knowledge elements for laser drilling system that will be optimized by an expert system. This system comprises oil and gas well parameters, rock properties, and laser properties and parameters. Based on these data, the corresponding rate of penetration and drilling time are evaluated

Dispersion model evaluation of PM2.5, NOx and SO2 from point and major line sources in Nova Scotia, Canada using AERMOD Gaussian plume air dispersion model

Abstract AERMOD was used to model the air dispersion of point and major line emissions of PM 2.5 in Halifax and Pictou, NO X in Halifax and SO 2 in Halifax, Sydney and Port Hawkesbury, Nova Scotia, Canada. Emission inventory data for 2004 were used in simulations within four, 50 km x 50 km, domains over annual, monthly and 1–hour averaging periods. Annual averaged surface concentration maps are reported. Modeled versus observed comparisons were made within each domain at the Government, National Air Pollution Surveillance (NAPS) monitoring sites (discrete receptors). Evaluation of the model was conducted on the annual, monthly and hourly results using a number of statistical methods that included R 2 , fractional bias, normalized mean square error and the fraction of predictions within a factor of two of the observations. The AERMOD model evaluation showed that there was good agreement between the modeled and observed SO 2 concentration for the annual and monthly comparison but less skill at estimating the hourly comparisons for SO 2 in Halifax and Sydney. AERMOD showed poor model skill at predicting SO 2 in Port Hawkesbury over the same averaging periods. The model evaluation for PM 2.5 in Halifax, PM 2.5 in Pictou and NO X in Halifax showed poor agreements and model skill. The surface concentrations from the point and major lines sources in all domains from all metrics were found to be well below the National Air Quality Standards. AERMOD has shown its utility as a suitable model for conducting dispersion modeling from point and line sources in Nova Scotia with good model skill for estimating annual and monthly SO 2 concentrations in Halifax and Sydney. The study highlights the validity of using emission inventory data to estimate the surface impact of major point and line sources within domains containing complex terrain, differing land use types and with large variability within the annual meteorology.

Automatic model calibration applying global optimization techniques

This paper summarizes a study aimed at the application of global optimization techniques for the purpose of quantitative characterization of the Wolfville formation located in Nova Scotia, Canada. Aquifer parameters (transmissivity, storativity, areal recharge and boundary flux) are calibrated in order to yield the best possible match with the available field observations. The calibration is accomplished using a global approach to the inverse procedure in “black box” systems optimization which makes possible the simultaneous fitting of several tens of parameters. This study indicates that, even for a limited number of optimized parameters, a global search procedure should be considered. Numerical results are presented and discussed to show the validity of the approach.

Non-newtonian effects on the drag of creeping flow through packed beds

Abstract Slow flows of non-Newtonian fluids through packed beds of solid particles are studied numerically and analytically using the free-surface cell model to account for the interactions between particles. The flow problem of a Carreau fluid is solved by the finite difference method and that of a second-order fluid by the perturbation method. It is shown that the flow drag decreases with a decrease in the flow behavior index and with an increase in the characteristic time. The degree of this reduction is found to be more significant at low voidages. The numerical results are found to be closer to the lower bounds obtained using variational principles by earlier investigators. The perturbation solutions predict that the second normal stress difference coefficient has a significant influence on the flow resistance. The flow resistance can either increase or decrease with an increase in the Deborah number, according to the values of the second normal stress difference coefficient. The results are found to be in agreement with the experimental findings that the viscoelastic flow through packed beds can exhibit a rapid increase in the flow resistance, over and above that expected for a comparable viscous fluid, in the second normal stress difference coefficient range for most real viscoelastic fluids.

Stochastic Analysis of Macrodispersion in a Semi‐Confined Aquifer

In this paper, the macroscopic dispersion resulting from one‐ and two‐dimensional flows through a semi‐confined aquifer with spatially variable hydraulic conductivity K which is represented by a stationary (statistically homogeneous) random process is analyzed using the spectral representation technique. Stochastic fluctuation equations of the steady flow and solute transport are solved to construct the macroscopic dispersive flux and evaluate the resulting macrodispersivity tensor in terms of the leakage factor and input covariances describing the hydraulic conductivity in a semi‐confined aquifer bounded by a leaky layer above and an impervious stratum below. The macrodispersivity tensor is studied using some convenient forms of the log hydraulic conductivity process. The sensitivity of the resulting macrodispersivity to the input covariances is discussed along with the influence of the leakage factor for both one‐ and two‐dimensional flows. It is found that the longitudinal macrodispersivities are increased due to the presence of leakage, while the transverse macrodispersivities are reduced due to leakage.

A boundary element method for stochastic flow problems in a semiconfined aquifer with random boundary conditions

A boundary element technique will be developed to deal with steady state flows through a shallow aquifer with random boundary conditions. The aquifer is bounded by a leaky layer above, and an impervious stratum below. The flow problem is formulated in terms of a stochastic boundary value problem involving a Helmholtz equation. A formulation of the boundary element method for the stochastic mixed boundary value problem is presented. The moments of unknown random hydraulic head can be obtained by application of an expectation operation to the boundary element formulations. A numerical method to evaluate hydraulic head moments on boundaries and inside the domain is then developed. The influence of the spatial structure of the boundary conditions on the hydraulic head statistics is discussed and the results are compared with some analytical solutions for one-dimensional flow problems for the purpose of verification of the numerical algorithm. The significance of the presence of the leaky layer on the hydraulic head statistics is also investigated. A numerical example for more general steady state flows through a semiconfined aquifer is presented.

Expert System Knowledge Management for Laser Drilling in the Oil and Gas Industry

The main drilling technique in the oil and gas industry has been rotary. Nevertheless, during the last decade, laser drilling has been investigated. Intensive research work has examined the soundness of this new drilling technique and its profitability. The laser drilling literature has confirmed that this novel technique performs better and faster than the conventional rotary drilling technique. Since the drilling time is reduced, the drilling costs are decreased, and the project profitability is increased. Furthermore, laser drilling eradicates the problem of contaminated water, soil, and rocks since water is used instead of toxic muds while drilling. This paper introduces the knowledge management process for an expert system that is the laser drilling system optimizer (LDSO). Then the development stages are described. The LDSO is an innovation since it is the first expert system developed for laser drilling in the oil and gas industry. It is a knowledge-based optimization system

Boundary element method for analyzing flow through a random semiconfined aquifer

With the aid of perturbation technique a boundary element procedure is developed for solution of two-dimensional Helmholtz equation with a random parameter of small variability. The perturbation boundary element method does not require specification of probability density function of the parameter but only its mean and standard deviation. The method is used to analyze steady-state groundwater flows in a horizontal shallow semiconfined aquifer (homogeneous and isotropic) of probabilistic properties. To illustrate the applicability of the method, a simple numerical example is presented. As the nature of perturbation method suggests, the developed method is valid only when the perturbed value of the parameter is of a small order.

Stochastic approach for groundwater flow in a semiconfined aquifer subject to random boundary conditions

Abstract A methodology is presented for analyzing the groundwater flow through a shallow semiconfined aquifer with random parameters, governed by the Helmholtz equation and subject to stochastic boundary conditions. Stochasticity in an aquifer parameter is considered along with the stochasticity in the Dirichlet and Neumann boundary conditions. The hierarchical equations based on the expansion of the potential into the perturbation series are derived and the regular boundary element procedure is applied for obtaining the solutions of these equations. The standard deviation in the potential is observed to increase with an increase in either the standard deviation in the random quantities or the strength of the correlation between the random quantities. The boundary element method based on perturbation does not require specification of the probability density function of the parameters but only their expectations, variances and the covariance of the random quantities. The applicability of the method is demonstrated by presenting a groundwater flow example as well as by comparing the numerical results with analytical solutions for a special case without the Neumann boundary condition uncertainty.

Multiple-Solution Nature of Chaos Number-Oriented Equations

Nature is characterized by its chaotic behavior. The forces and processes that individually and collectively control the phenomena of the universe independently of human intervention are described by various equations. These equations need to be solved to understand the behavior of nature. Unfortunately, conventional mathematics has not been able to deal with all nature problems. Therefore, there is an urgent need for novel mathematics to solve complex problems. This paper lays the foundation for solving nature chaotic equations and shows how the universe dimensions determine the nature and number of solutions. It introduces the process to solve and identify the solutions for the simple linear equation x = 2 and quadratic equation x2 = 4 in zero, one, two, three, and more dimensions. As a result, this paper establishes an important fact for chaos equations that is all equations have multiple solutions.