Rivers State University of Science and Technology

About: Rivers State University of Science and Technology is a education organization based out in Port Harcourt, Rivers, Nigeria. It is known for research contribution in the topics: Population & Threatened species. The organization has 1826 authors who have published 1833 publications receiving 15183 citations.

Using Difference Factor Thermodynamics Models in Hydrate Formation Prediction During Surface Production Well Testing

Abstract: All oil fields under water-drive, including gas-cap and depletion reservoirs may produce some water along with oil. This co-production of water causes an additional set of challenges: corrosion, scale/salts deposition, disposal of the water itself, and gas-hydrate formation. Hydrates are ice-like solids that form when free water and natural gas combine at high pressure and low temperature. This can exist in gas and gas/condensate wells, as well as in oil wells. Hydrate formationis a very serious challenge and can result in a huge loss especially during production. It's also one of the major challenges encountered during surface production well testing and it is controlled by several factors which include thermodynamics and kinetics of the system. This study presents a thermodynamic model under operating field conditions, which centers on changes in the Langmuir constant of the guest molecule(s) which is an important parameter in the hydrate formation process. In this study, real-time production data acquisition system was used to acquire surface production well testing data such as pressure, temperature, and choke size, from a hydrate well. The acquired real-time data were used to determine the effect of the variation in choke size on Langmuir constant and therefore on hydrate formation. Evaluating the Langmuir constant for large cavity under field conditions using a generalized correlation, the Difference Factor method was developed and expanded to incorporate the choke sizes variation. The correlation shows that Langmuir constant (decreases) is inversely proportional to the choke size (increases) causing a decrease in the rate of hydrate formation. Due to an increase in choke size, Langmuir constant approaches zero, therefore the product of fugacity and Langmuir constant which is the driving force for hydrate formation approaches zero, leading to zero hydrate formation.

Do McKinnon lists provide reliable data in bird species frequency? A comparison with transect-based data

Abstract: Although occurrence-based listing methods could provide reliable lists of species composition for a site, the effective reliability of this method to provide more detailed information about species frequency (and abundance) has been rarely tested. In this paper, we compared the species frequencies obtained for the same set of species-rich sites (wetlands of central Italy) from two different methods: McKinnon lists and line transects. In all sites we observed: (i) rapid cumulating curves of line transect abundance frequencies toward the asymptote represented by the maximum value in McKinnon occurrence frequency; (ii) a large amount of species having a low frequency with line transect method showing a high range of variation in frequency obtained by McKinnon lists; (iii) a set of species having a subdominant (>0.02- 0.05) frequency with line transect showed all the highest value in McKinnon frequency. McKinnon lists provides only a coarse-grained proxy of species frequency of individuals distinguishing only between common species (having the highest values of McKinnon frequency) and rare species (all the other species). Although McKinnon lists have some points of strength, this method does not discriminate the frequencies inside the subset of common species (sub-dominant and dominant species). Therefore, we suggest a cautionary approach when McKinnon frequencies should be used to obtain complex univariate metrics of diversity.

Municipal Solid Waste Characterization and its Associated Vector-borne Diseases within the Vicinity of Dumpsite and Controlled Site

Abstract: This paper presents the composition of municipal solid waste in Uyo and vector-borne diseases associated with municipal solid waste within the vicinity of the dumping site (less than 1 km) and controlled site (above 1 km). The compositions of municipal solid waste were determined using samples obtained from Uyo village road waste dumping site. The dumpsite receives solid waste from all the communities in Uyo local government area. In order to assess the public perception of vector-borne diseases associated with municipal solid waste, sample survey method was adopted, which involved the administration of 500 questionnaires of which 250 were administered to the residents who lived less than 1 km from the boundary of the waste dumpsite and 250 questionnaires were also administered to the communities living further away. The compositions and percentages constituent by mass revealed the following: Organic waste component constitute 53.86% and inorganic constituted a waste portion of 46.14%. For vector-borne diseases associated with municipal solid waste, the results indicated that 70.8% of the respondents attended tertiary education (OND/NCE and above), so the issues associated with municipal solid waste may not be strange to them. A significant number of respondents are aware that the origin of municipal solid waste is residential, commercial, industrial, market, street sweeping and industrial sectors. Respondents are more aware that rats, flies, mosquitoes, birds, pigs and cockroaches are vector-borne diseases associated with municipal solid waste. The findings in this study will be useful in a comprehensive solid waste management program which encompasses sweeping, storage, collection and disposal of solid waste. However, the waste can be best treated if any of these techniques are utilized composting, gasification and energy recovery in future for further reduction of waste.