International Journal of Engineering Research in Africa Vol. 2

Abstract: Exploration and production activities have moved into more challenging deep-water and subsea environments. Many of the clastic reservoirs in these environments are characterized by thick overburden, HP-HT and largely unconsolidated formations with challenging sand management issues. For effective overall field/reservoir management, it is crucial to know if and when sand would fail and be ultimately produced. Field-life sanding potential evaluation and analysis, which seeks to evaluate the sanding potential of reservoir formations during the appraisal stage and all through the development to the abandonment stage, is therefore necessary so that important reservoir/field management decisions regarding sand control deployment can be made. Recent work has identified Unconfined Compressive Strength (UCS) as a key parameter required for the evaluation and analysis of sanding potential of any reservoir formation. There is therefore the need to be able to predict this important sanding potential parameter accurately and in real time to reduce the level of uncertainties usually associated with sanding potential evaluation and analysis. In this work, neural network coded in C++ was trained with log-derived petrophysical, geomechanical and textural data to develop a stand-alone model for predicting UCS. Real-time functionality of this model is guaranteed by real time data gathering via logging while drilling (LWD) and other measurement while drilling (MWD) tools. The choice of neural network over and above other methods and techniques which have been widely used in the industry was informed by its ability to better resolve the widely known complex relationship between petrophysical, textural and geomechanical strength parameters.

Abstract: Advances in micro-CT imaging of porous materials provide the opportunity to extract representative networks from the images. This improves the predictive capability of pore scale network models to predict multiphase flow transport properties. However, all these predictions need to be validated with laboratory experimental data. The experimental data for such validation may either be from the literature or newly conducted laboratory experiments on same outcrops. This paper presents the review of some of the available Pc – Sw experimental data available in the literature for validating the predictions made by network models.

Abstract: The effect of some process parameters on the weight of zinc deposited on mild steel in a typical electroplating process is reported. The study indicates that the weight of zinc deposited on mild steel during the process is affected by plating temperature, current density, plating bath pH and plating time. The study established that optimum deposition of zinc is achieved at plating temperature of 320C, plating bath pH of 4.4, current density 40mA/cm2 and plating time of 30 minutes. 8.7mg of zinc was deposited at optimum deposition conditions. The profile of the zinc deposited decreases after optimum deposition is attained.

Abstract: An experimental study has been carried out using a tube bank representing a section of a tube bundle. The bank comprised 3 columns each of 10 stainless steel electrically heated tubes of 3mm outside diameter with pitch to diameter ratio of 1.5 in an in-line arrangement. Flow rate through the test section was controlled. Each tube in the central column was instrumented to permit determination of the tube temperature and heat flux, hence permitting calculation of the heat transfer coefficient. These tests were carried out using distilled water at nominal atmospheric pressure over a range of heat fluxes between 6 - 21 kW/m2. Results of the heat transfer tests are presented and compared with correlations used for conventionally sized bundles. Correlations developed for large tube bundle overestimate the experimental results.

Abstract: This work is an investigation of the performance characteristics of an offset journal bearing lubricated with a fluid with couple stresses taking into consideration the elastic deformation of the liner. The couple stresses might be expected to appear in noticeable magnitudes in liquids containing additives with large molecules. The modified Reynolds equation has been solved using the finite difference method. Load carrying capacity, attitude angle, side leakage and friction coefficients are determined for various values of couple stress parameter of a rigid and deformable bearing. It is found that, the static characteristics of journal bearings lubricated with couple stress fluids are improved compared to journal bearings lubricated with Newtonian fluids. It is concluded that, the elastic deformation of the bearing has significant influence on the bearing characteristics.

Abstract: The numerical solution of the partial differential equation (PDE) of the received signal strength from fixed transmitting stations as derived from Maxwell’s wave equation is presented in this paper. The received signal strength level (RSSL) at a defined distance from a source point (base transceiver station) was simulated for two real environments described as Sites 1 and 2. The values of RSSL were taken at different nodes and at different radial directions away from the source point using the Finite Element Method (FEM) tool of the MATLAB package. The hexagonal geometry with no describing function was assumed for the cell. A 3-D model of the power received versus distance was obtained, and the numerical solution of the model presented. The numerical results obtained from the 3-D model were compared with the results of the drive test conducted in Sites 1 and 2 for functional GSM radio networks in the areas. The suitability of the method was justified for the two sites with a 5.55dB standard deviation of error for network A in Site 1 and 8.36dB and 3.40dB standard deviations of error for networks A and B respectively for Site 2.

Abstract: There are several reasons why public power supply policy in Nigeria needs to be reviewed. This paper points out the justification based on the statistical inferences drawn from an elaborate nested experimental design model fitted to a 3-year historical life-data of power failure obtained from an electricity power agency in Nigeria. Our results suggest that energy crisis is at its threshold in Nigeria and it is therefore advocated that adequate and appropriate steps need to be taken to stave off the declining trend.