Tectonic control on the distribution of onshore mud volcanoes in parts of the Upper Benue Trough, northeastern Nigeria

Onshore mud volcanoes are rare geological phenomena, which in Nigeria were reported for the first time few years ago in the Upper Benue Trough. In this study a detail geological mapping of the area of mud volcanoes occurrence was carried out, with the primary aim of defining their relationship, if any, to the structural geology there. The systematic field reconnaissance included field observations of the structural features, as well as analysis of the location and distribution of the onshore mud volcanoes, marking their locations on the topographic and geological maps, analysis of the aerial photographs and satellite images. The study area covered the central part of the Upper Benue Trough where the onshore mud volcanoes were found. The study area is the part of a sedimentary basin comprising Cretaceous clastic rocks that have been deformed intensively by a network of faults often embedded in the underlying Precambrian basement. This network of faults underwent a rejuvenation period from the Aptian to the Palaeocene. The most prominent tectonic structure in the study area is the NE - SW trending Kaltungo Fault Zone, however, there are other minor faults with N - S and NW - SE trends. This study shows that the mud volcanoes found in the study area are usually located near or within fault zones, within the outcropping Upper Cretaceous Yolde Formation and Upper Bima Sandstone, both of which were deformed by the Kaltungo faults, as well as by other minor faults. Worldwide, incidences of onshore mud volcano formation are usually attributed to areas of tectonic activity, rapid sedimentation or hydrocarbon occurrence. In this study, the interpretation of the field observations and mapping results, combined with information on the structural evolution of the study area and seismic pattern (very scarce), have led to the conclusion that the location of onshore mud volcanoes in the Upper Benue Trough, being located along the fault zones, is structurally controlled. The close relationship between mud volcano location and the structural framework of the area may be interpreted as one of several possible subsurface geological responses to present tectonic activity

Effect of Climatic Governing Parameters on the Performance of Solar Adsorption Refrigeration System

Solar energy is a renewable resource, clean and ecologically friendly. Solar thermal energy is attractive alternative energy to drive the adsorption of refrigeration machines. This work presents a numerical investigation of the effect of climatic governing parameters such as ambient temperature and component temperatures on the performance of solar adsorption refrigeration systems using methanol/activated charcoal pairs. Activated carbon as adsorbent and methanol as a refrigerant is selected. Some predictive empirical equations accounting for heat balance in the solar collector components, instantaneous heat and mass transfer in adsorbent bed, and performance parameters were presented. Interactive C++ programming was developed to carry out the parametric study of some climatic factors such as ambient temperature and solar radiation intensity with aperture width of 0.14 m, collector length of 2.1m on the system performance. The effect of ambient temperature and component temperatures with aperture width, collector length, on specific cooling power (SCP), refrigeration cycle COP (COPcycle), and solar coefficient of performance (COPs) are being investigated. The results are presented in form of profiles such as pressure developed in the generator, specific cooling power and system coefficient of performance profiles, under varying weather conditions and ambient temperature, operating conditions of evaporating temperature, Tev = 0 oC, condensing temperature, Tcon = 30 oC and desorption temperature of 100 oC, The influences of operating and design parameters on the system performance are significant. The system performance shows no appreciable changes with varying condenser temperature with significant effect with varying evaporation and desorption temperature. It is shown clearly that for different desorption temperatures below 120 oC there is an appreciable effect on the system performance parameters. The study has revealed the system attains a promising performance of the adsorption refrigeration system using AC / methanol pair driven by solar energy. Keywords: Adsorption; Refrigeration; Activated carbon/methanol; Simulatio

Offshore Topside Rotating Packed Bed as Process Intensified Alternative for Natural Gas Sweetening and Dehydration

This work is aimed at investigating the benefits of replacing conventional process unit operations with process intensified ones in offshore applications. This ensures that better use is made of raw materials, lower energy consumption and a reduced plant volume was achieved. Specifically, a rotating packed bed technology has been used for gas dehydration and sweetening. To achieve the aim of this study, a process intensification approach is used to redesign mature absorption processes to more compact and efficient one. Process simulation using Aspen Hysys was carried out for Triethylene glycol dehydration and monoethanolamine sweetening. More than 36-fold absorption unit size reduction was achieved thereby effecting large decrease in capital and operating costs compared to the conventional packed columns currently utilized in the offshore oil and gas industry. The process intensified technologies therefore can be deployed for offshore applications where space and size considerations are of utmost importance