A method of obtaining petrophysical and single-and multi-phase properties of reservoir rocks without the use of Special Core Analysis techniques is presented. The approached involved three-dimensional image reconstruction from 2-D images of reservoir rocks obtained by micro-computer tomography. Two rock samples were used for the study, namely, a Carbonate-28 rock sample and a Castlegate sandstone. The Carbonate-28 sample was studied at two different resolutions of 1.33 microns and 0.133 microns; while the Castlegate sandstone was investigated at a resolution of 5.6 microns. Network models were extracted from the pore architecture models (PAMs) obtained from the 3-D image reconstruction. The geometrical and topological properties of the extracted networks were then studied; this was followed by numerical flow simulation to derive the single-and multi-phase properties of the rocks studied. The geometrical and topological characteristics of the reconstructed pore architecture models were analysed with the aid of a pore analysis software tool (PAT). The main geometry and topological -characteristics studied included the pore size distribution, pore shape factor, and pore connectivity (in terms of coordination number and specific Euler number). Single-and multi-phase flow properties, namely: average porosity, absolute permeability, relative permeability, and capillary pressure, were measured for all three structures. Results obtained showed that pore size connectivity, and pore size distribution had the greatest impact on flow properties. Specifically, it was observed that the larger the interconnected pore sizes, the greater the absolute permeability; whereas observed permeability was low for interconnectedness involving smaller pores, even with high pore connectivity (that is, favorable specific Euler number). These results can be applied in reservoir characterization to generate flow properties for reservoir rocks; which can be utilized in reservoir simulation and reservoir engineering calculations.
An experimental organic waste to biogas conversion mini-plant that works by anaerobic digestion has been designed, fabricated and tested. The demonstration involved the use of primarily, a biodigester and few other components. The organic waste was made into slurry and digested anaerobically for 14 days at an ambient temperature range of 28 to 32°C. The flame of biogas generated burnt with smokeless blue flame, indicating the presence of a colourless odourless gas called methane. The biodigester achieved a conversion efficiency of 64 percent. This equipment can be used to meet a good percentage of the fuel needs in Nigeria.
Good understanding of the flow regimes is necessary for accurate interpretation of well test results. Partially completed or penetrating wells develop flow geometries which are different from the radial flow model on which conventional well test analysis is based and so the radial flow equation will not be adequate for analysing the transient behaviours resulting from such wells. A threefold, approach, namely, Model Preparation, Numerical Reservoir Simulation, and Well Test Analysis was used in this work to study the effects of partial penetration on the transient pressure response of partially penetrating wells. The effects of anisotropy, wellbore storage, position of partial completion and penetration were all considered. Spherical flow approximation was used for the description of wells with partial completion and partial penetration. In the analysis, three flow regimes were found to appear on the transient pressure response. Pressure drop was greatest in wells with very low penetration ratio. The position of partial completion had no effect on pressure transient response. Vertical permeability is very important in predicting gas or water coning or performance of horizontal wells. This is very useful in for completion engineering optimisation and as well provides a good rationale for drilling horizontal wells. Also Knowledge of the vertical anisotropy will aid reservoir development and the planning of future secondary recovery.
The effect of image resolution on the measured geometry and topological characteristics of network models extracted from 3-D micro-computer tomography images has been investigated. The study was conducted by extracting geologically realistic networks from images of two rock samples, imaged at different resolutions. The rock samples involved were a Castlegate Sandstone and a Carbonate-28 reservoir rock. Two-dimensional images of these rocks were obtained at a magnification of ×50. The carbonate sample was studied at two different resolutions of 0.133 microns and 1.33 microns, while the sandstone was studied at 5.60 microns. Three-dimensional images of these 2-D images were obtained via image reconstruction, to generate the pore architecture models (PAMs) from which networks models of the imaged rocks were extracted with the aid of Pore Analysis software Tools (PATs). The measured geometry and topology (GT) properties included Coordination Number, Pore Shape Factor, Pore Size Distribution, and Pore Connectivity. The results showed that the measured geometry-topology (GT) characteristics of a network model depend greatly on the image resolution used for the model. Depending on the micro-structure of the reservoir rock, a minimum image resolution is necessary to properly define the geometrical and topological characteristics of the given porous medium.
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