-
Development of Finite Difference Explicit and Implicit Numerical Reservoir Simulator for Modelling Single Phase Flow in Porous Media
Aphu Elvis Selase,
Brantson Eric Thompson,
Addo Bright Junior,
Akunda Doreen
Issue:
Volume 7, Issue 6, December 2018
Pages:
242-259
Received:
26 June 2018
Accepted:
4 October 2018
Published:
29 October 2018
DOI:
10.11648/j.earth.20180706.11
Downloads:
Views:
Abstract: Every petroleum reservoir requires some means of predicting future performances as well as optimizing recovery of hydrocarbons under various operating conditions. Moreover, there is a need to simulate fluid flow in porous media due to the uncertainty and heterogeneity that is associated with petroleum reservoirs. Therefore, this study developed 1D finite difference explicit and implicit numerical reservoir simulator for modeling single phase flow in porous media. The explicit and implicit simulator developments consist of physical modeling, mathematical modeling, discretization of the models with finite difference scheme and transformation of the models into computer algorithms. Matlab codes were written to describe the fluid flow process to obtain the reservoir pressure distributions for each grid block at each timestep calculation. The explicit formulation linear equation was solved by the direct method while the implicit method was solved by the Jacobi iterative method. The numerical examples graphical plots generated from the simulator illustrate the average reservoir pressure depletion for the finite difference grid blocks. The plots for both the explicit and implicit method indicate decline in average reservoir pressure with time. The explicit and implicit simulators show that the implicit formulation is unconditionally stable than the explicit formulation. This is because the explicit method under certain conditions generates errors in the numerical solutions which tend to go zero during subsequent timestep calculations. Additionally, the porosity sensitivity analyses performed show that the average reservoir pressure decline as the porosity decreases from 30% to 10%. Material balance method was used to determine the average reservoir pressure decline for a one-year production period. The estimated recovery factor at the bubble point pressure is 0.68% of the original oil in place. This low recovery factor is a characteristic of an expansion-drive reservoir which has the least efficient recovery mechanism. Finally, the 1D explicit and implicit finite difference numerical simulators for predicting single phase flow reservoir pressure distributions during production periods are stepping stone towards implementing multiphase fluid flow formulations.
Abstract: Every petroleum reservoir requires some means of predicting future performances as well as optimizing recovery of hydrocarbons under various operating conditions. Moreover, there is a need to simulate fluid flow in porous media due to the uncertainty and heterogeneity that is associated with petroleum reservoirs. Therefore, this study developed 1D ...
Show More
-
Nature of Old Maps: As Primary Source Materials for Historical Geography
Issue:
Volume 7, Issue 6, December 2018
Pages:
260-267
Received:
20 August 2018
Accepted:
30 September 2018
Published:
29 October 2018
DOI:
10.11648/j.earth.20180706.12
Downloads:
Views:
Abstract: This paper discusses on the meaning and the nature of old maps of both small and large scales for historical geography. The old map can be an object of research itself as well as a source for research on something else. But both research directions have been closely connected with each other, and also each research direction needs inevitably another. Roughly speaking, small scale old maps mean mainly world maps, although they have no accurate scale. They commonly reflect the enormous expansion of geographical knowledge acquired during periods of exploration of little-known places, and they clearly reflect the perception of space that pertained at the time when the map was drawn. In case of large scale maps like manorial maps and town/village maps as cadastral ones, they express much local information in which local people interested or according to the land system or land planning in different times. Some large/middle scale maps show more formal land planning, those showing grid land planning like Centuria in Roman Empire, Jori Plan in 8-9th century Japan and Townships in British American colonies and later US and Canada. Those large/middle scale maps usually express various land units within each grid in spite of a land itself usually stretched continuously. Old maps are very important as primary source materials for historical geography, but researchers should consider the nature of old maps. They are commonly without accurate scale, physical situation and standard for drawing and describing. And furthermore, many old maps were made under the thought or regulation for land planning, when those are used as source materials.
Abstract: This paper discusses on the meaning and the nature of old maps of both small and large scales for historical geography. The old map can be an object of research itself as well as a source for research on something else. But both research directions have been closely connected with each other, and also each research direction needs inevitably anothe...
Show More
-
Method Established for Source Apportionment of Human Health Risk in Regional Atmospheric Environment
Huanbo Wu,
Xiao Liu,
Wenkai Guo,
Qiang Chen
Issue:
Volume 7, Issue 6, December 2018
Pages:
268-274
Received:
18 October 2018
Accepted:
6 November 2018
Published:
30 November 2018
DOI:
10.11648/j.earth.20180706.13
Downloads:
Views:
Abstract: Previous studies of source apportionment were only focused on contribution rates of pollutants concentration, but have not evaluated contribution rates of influencing degree of pollutants on people's health. To assess the health risk of pollution source to human health in the atmospheric environment, a method of source apportionment of human health risk, which the health risk assessment method combined with the source apportionment receptor model, was established in this research. Based on each pollution source contribution to metallic elements in inhalation particle matter (PM10) at the sampling site of Lanzhou University, the health risks contribution rates to exposed group were estimated according to the established method, and compared with the results of source apportionment. The results were as follows: the concentration contribution rates calculated by chemical mass balance (CMB) model rank from high to low as vehicle exhaust dust (43.4%), urban fugitive dust (29.9%), coal fly ash (21.5%), construction cement dust (1.2%) and metal smelt dust (0.7%); the non-carcinogen hazard index (Rn) contribution rates rank from high to low as urban fugitive dust (87.7%), vehicle exhaust dust (5.9%), coal fly ash (3.0%), metal smelt dust (2.5%) and construction cement dust (0.9%); the cancer risk value of carcinogen (Rc) contribution rates rank from high to low as urban fugitive dust (97.1%), vehicle exhaust dust (1.7%), coal fly ash (0.5%), metal smelt dust (0.5%) and construction cement dust (0.2%). Apparently, the concentration contribution rates were very different from the hazard index of non-carcinogen (Rn) contribution rates and the cancer risk value (Rc) contribution rates. The source with the highest concentration contribution was not the major influence on human health. The influence of source with the contribution rate lowest concentration contribution on human health should not be ignored. This method could also be used in health risk assessment of other pollutants from other sources.
Abstract: Previous studies of source apportionment were only focused on contribution rates of pollutants concentration, but have not evaluated contribution rates of influencing degree of pollutants on people's health. To assess the health risk of pollution source to human health in the atmospheric environment, a method of source apportionment of human health...
Show More
-
Influence of Ventilation Modes on Carbon Dioxide Fixation of Chlorella vulgaris in a Flat-Plate Photobioreactor
Yongfu Li,
Ruiqian Li,
Haifang Fu,
Ying Gao
Issue:
Volume 7, Issue 6, December 2018
Pages:
275-282
Received:
9 December 2018
Published:
11 December 2018
DOI:
10.11648/j.earth.20180706.14
Downloads:
Views:
Abstract: Microalgae have the ability to mitigate CO2 emission with a high productivity, thereby having the potential for applications in reducing CO2 with high concentration. To date the effect of different ventilation modes in photobioreactor on the high level CO2 fixing capacity was still unclear. To explore an efficient, convenient and cheap aerating method for high concentration CO2, an inner parallel flat-plate photobioreactor configuration (IPFP) was designed and the effect of inner-mixing ventilation and intermittent ventilation modes on the CO2 fixation rate (CFR) in a laboratory-scale IPFP was determined. Chlorella vulgaris, a promising freshwater green algal strain with high CO2 fixation rate under CO2 concentration lower than 5% (v/v) but cannot survive under 15% CO2, was used to perform the experiments. Results showed that both of the novel ventilation modes can effectively enhance microalgal performance on growth and carbon biofixation rates when 15% CO2 was directly provided. The CFR of Chlorella vulgaris in this photobioreactor ranged 1.30 to 1.78 g CO2L-1d-1. The pH value of cultural medium was also determined. Results showed that the distribution of pH values was uniform in the IPFP cross section during the inner-mixing ventilation mode, which indicating a good mixing characteristic of the fluid in the IPFP. In the intermittent ventilation mode, the pH values demonstrated periodical variation with the maximum value of 8.2 and the minimum value of 6.5. Aerating 15% CO2 for 12 minutes and air for 48 min in one hour (12 min 15% CO2/48 min air) provided a longer period in pH<7.0 than that of aerating 15% CO2 for 6 minutes and air for 54 min in one hour (6 min 15% CO2/54 min air), and thus, was more beneficial to the CFR. IPFP with an inner-mixing ventilation mode effectively enhances the performance of C. vulgaris on microalgal growth and CO2 biofixation, indicating that this PBR has the potential for use in the field of carbon reduction.
Abstract: Microalgae have the ability to mitigate CO2 emission with a high productivity, thereby having the potential for applications in reducing CO2 with high concentration. To date the effect of different ventilation modes in photobioreactor on the high level CO2 fixing capacity was still unclear. To explore an efficient, convenient and cheap aerating met...
Show More
-
A New Application of the Digital Synthetic Schlieren in Lab Experiments of the Internal Waves
Qingjun Meng,
Yanzhen Gu,
Peiliang Li,
Xinzhu Wu
Issue:
Volume 7, Issue 6, December 2018
Pages:
283-288
Received:
9 December 2018
Published:
11 December 2018
DOI:
10.11648/j.earth.20180706.15
Downloads:
Views:
Abstract: Laboratory experiment is an important method in the study of ocean internal waves, and the schlieren technique is an effective way to observe the internal waves in the laboratory. The digital synthetic schlieren technique is mostly applied to two-dimensional density-stratified flows. The technique is improved by setting up the Charge Coupled Device (CCD) vertically to shoot the reference images in this research. Then the three-dimensional density-stratified flows can be detected in this way. The authors attempt a set of lab experiments to verify the rationality of this technique. There is a horizontally moving spherule with constant velocity at the interface of the two-layer stratified water in the experiment. The moving spherule generates internal waves between the two-layer fluids. The authors successfully capture the three-dimensional structure of the internal waves generated by the horizontally moving spherule. It is obvious that the internal waves have characteristics of the Kelvin Internal Wake and the quantitative parameters agree well with the previous studies. The experimental results reveal that the improved digital schlieren technique is rational and feasible in the lab internal waves observations. The detailed three-dimensional structure of the internal waves, the internal wave energy distribution and propagation in the whole field and the nonlinear interactions between the internal waves can be further studied through this method in the future.
Abstract: Laboratory experiment is an important method in the study of ocean internal waves, and the schlieren technique is an effective way to observe the internal waves in the laboratory. The digital synthetic schlieren technique is mostly applied to two-dimensional density-stratified flows. The technique is improved by setting up the Charge Coupled Device...
Show More
-
First Mention of Unusuropode castroi Duarte & Santos, 1962 (Crustacea: Isopoda) in the Upper Cretaceous of Gara es Sbâa Lagerstätte, South-Eastern Morocco
Joan Corbacho,
Scott Morrison,
Máximo Alonso
Issue:
Volume 7, Issue 6, December 2018
Pages:
289-293
Received:
1 November 2018
Accepted:
16 November 2018
Published:
20 December 2018
DOI:
10.11648/j.earth.20180706.16
Downloads:
Views:
Abstract: This article presents an isopod that arrived at the Geological Museum of the Seminary, Barcelona (Spain) a few years ago, as part of the material compiled by the first author of this article (J C) in an outcrop of Gara es Sbâa (Morocco). This isopod is identified as Unusuropode castroi, is the first reference to this species outside of Brazil and also represents the first formal description of Unusuropode castroi in Africa. Gara is Sbâa, is located in the region of Kem Kem (southeast of Morocco) and is presented as a new locality for the isopod Unusuropode castroi, from the Upper Cretaceous (Cenomanian / Turonian), previously described only in the Turonian of the Apodi Group, Arenito Açu, state of Ceará Brazil. With this new isopod the statement of Martill et al. [1] is reinforced, indicating the affinities between the faunas of South America and Morocco during the Cretaceous. This document presents the two types of Unusuropode castroi differentiated by their size that also appear in Brazil, described by Duarte and Santos [2] as possible sexual dimorphism (see table 1 and figure 5, images b – c).
Abstract: This article presents an isopod that arrived at the Geological Museum of the Seminary, Barcelona (Spain) a few years ago, as part of the material compiled by the first author of this article (J C) in an outcrop of Gara es Sbâa (Morocco). This isopod is identified as Unusuropode castroi, is the first reference to this species outside of Brazil and a...
Show More
-
Assessment of Heavy Metal Contents and Pollution Risk in Reclaimed Soils of a Bauxite Mine
Issue:
Volume 7, Issue 6, December 2018
Pages:
294-300
Received:
19 September 2018
Accepted:
4 December 2018
Published:
28 December 2018
DOI:
10.11648/j.earth.20180706.17
Downloads:
Views:
Abstract: A study on the contents and pollution state of heavy metals in the soils at the Xiaoyi Bauxite Mine in Shanxi, China was conducted to provide a scientific basis for understanding and evaluating the risks of heavy metal pollution in reclaimed soils in mining areas. The contents of Cd, Cr, Cu, Pb, As, and Ni were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and evaluated with respect to the changes in their characteristics over different reclamation years. Using a single factor index and the Nemerow Pollution Index, the potential degree and risk of pollution were assessed. The mean concentration of Cd was 5.19 mg/kg, which exceeds the 0.3 mg/kg national standard in China by 17 times, while the concentrations of other elements did not exceed the national standard and there was no apparent pollution risk. With the extension of the reclamation time, the contents of Cd increased in the 0–15-cm layer and decreased in the 15–30-cm layer. Cadmium possessed the highest single pollution index, and exceeded the severe pollution level (Level 5), while the other five elements were at safe levels (i.e., lower than Level 1). The Nemerow Pollution Index ranged from 12.08–13.14, with an average of 12.43, and exceeded Level 5 pollution by 3–4 times, indicating a severe level of pollution. The soil being used to reclaim the mine was the main source of pollution, with the contents of six heavy metal elements exceeding the national standards. The soils in the reclamation area contain Cd pollution from the resource soil, manure, and dust. Therefore, for mine reclamation, the quality of the soil being used to reclaim the land should been stringently control.
Abstract: A study on the contents and pollution state of heavy metals in the soils at the Xiaoyi Bauxite Mine in Shanxi, China was conducted to provide a scientific basis for understanding and evaluating the risks of heavy metal pollution in reclaimed soils in mining areas. The contents of Cd, Cr, Cu, Pb, As, and Ni were analyzed by inductively coupled plasm...
Show More
