Abstract: Petroleum exploration and production in the region of the Niger Delta to date has mainly focused on the onshore, deltaic and offshore deep-water Miocene successions. Although Miocene turbidites have been the principal deep-water target, deeper-lying Oligocene sandstones are now being considered for exploration. This study targets an area beneath the Niger Basin slope at a present-day water depth of 800–1500 m. Within this study area, the Miocene to Recent sands above a burial depth of 3600 m show very good reservoir quality with porosities as high as 35% and permeabilities in the Darcy range. The aim of this study is to predict the reservoir quality and properties of the Oligocene sandstones below 3800 m using basin modelling to predict conditions where quartz cementation will take place and quartz cementation models to predict the amount of cementation and hence the potential porosity loss. Modelling results show that the Oligocene sandstones have been exposed to conditions favourable for quartz precipitation, but that less than 14% of the original porosity will have been occluded by quartz cement. These results are in agreement with elemental analysis from both petrophysical and petrological observation of thin sections. Although the deeper-lying Oligocene sandstones are likely to have reduced reservoir quality due to the presence of quartz overgrowth cementation, it appears likely that the volume of cement is relatively low and the Oligocene succession should be considered a viable play.

We reviewed the current state of waste management practices in Nigeria using examples from different parts of the country. Commonly practiced waste disposal methods in Nigeria, such as burial, open-air burning, and open dumping, were found to be ineffective and detrimental to public health and the environment. It was also shown that waste management cannot be successfully operated as a social service. Rather, the generator of waste must be held responsible. Problems confronting efficient waste management in Nigeria include the proliferation of unplanned settlements, traffic congestion, insecurity, and ignorance. An experimental model being used in Lagos State for the management of wastes may be the solution. Given the rate of population growth, industrialization, and urbanization, forward-looking and effective waste management plans need to be set in motion for the protection of public health. Such plans must involve all stakeholders, including the waste generators, the private sector, the informal sector, and regulatory agencies.

Abstract DOWNFLOW is a probabilistic code for the simulation of the area covered by lava flows. This code has been used extensively for several basaltic volcanoes in the last decade, and a review of some applications is presented. DOWNFLOW is based on the simple principle that a lava flow tends to follow the steepest descent path downhill from the vent. DOWNFLOW computes the area possibly inundated by lava flows by deriving a number, N , of steepest descent paths, each path being calculated over a randomly perturbed topography. The perturbation is applied at each point of the topography, and ranges within the interval ±Δ h . N and Δ h are the two basic parameters of the code. The expected flow length is constrained by statistical weighting based on the past activity of the volcano. The strength of the code is that: (i) only limited volcanological knowledge is necessary to apply the code at a given volcano; (ii) there are only two (easily tunable) input parameters; and (iii) computational requirements are very low. However, DOWNFLOW does not provide the progression of the lava emplacement over time. The use of DOWNFLOW is ideal when a large number of simulations are necessary: for example, to compile maps for hazard and risk-assessment purposes.