Channel depositional environment

In some depositional environments, e.g. fluviatile channels, marked differences in reservoir thickness will be encountered. Hence the assumption of a constant thickness, or a linear trend in thickness across the field will no longer apply. In those cases a set of additional maps will be required. Usually a net oil sand (NOS) map will be prepared by the production geologist and then used to evaluate the hydrocarbon volume in place. 

Buried mat samples were collected from the sabkha, in pits or along artificial channels. They were selected to correspond to the modem mat samples in terms of depositional environments. The buried mat sample used for detailed geochemical studies has been collected from the sabkha two kilometers inland at a depth of 60 cm. Its sedimentary structure is well preserved and it contains 2% TOC. 

A typical barrier-island system can be divided into three depositional environments (barrier beach, lagoonal/bay, and tidal channel -delta complex) each of which contains a number of smaller subenvironments (2). This work focused on a typical bay-fill sequence in which bay sediments are overlain by tidal flat deposits... 

This study is based on a subset of samples from 317 localities in eastern Kentucky, northwestern Tennessee, western West Virginia and southwestern Virginia. Samples were collected primarily from channel sandstones in order to control, as closely as possible, for grain size and depositional environment. Most samples are medium sandstones. In a regional petrographic survey, 275 standard blue... 

Most commercial marine diatomite deposits exploit accumulations resulting from large blooms of diatoms that occurred ia the oceans during the Miocene geological epoch. Diatomite sediments older than the Jurassic period are rare in the fossil record. Commercial deposits of diatomite are accumulations of the fossil skeletons, which can occur in beds as thick as 900 m in some locations (5). Marine deposits must have been formed on the bottom of protected basins or other bodies of quiet water, undisturbed by strong currents, in an environment similar to the existing Santa Barbara Channel or Gulf of California (3,6). 

Relatively low permeability alluvial soils (silt, clay, and sandy clay), which corresponds with perching layers or aquitards. These soils were interpreted to be deposited in a low-energy, suspended load, fluvial-deltaic environment outside of channel zones. 

Data has been obtained from published sources and listed data held in the library of the Geological Survey of Namibia. This data has been used to assess the geochemical environment in the vicinity of channel fill and pedogenic uraniumbearing calcrete deposits. The data has been analysed by various methods and laboratories so direct comparison of the data has to be treated with caution. A summary table of the geochemistry of waters from each of the deposits is given in Table 1. 

The reaction is also influenced by the heat of reaction that develops during the conversion of the reactants, a problem in tubular screening reactors. In micro structures, the heat transport through the walls of the channels is facilitated owing to their small dimensions. The catalysts are deposited on the walls of these micro structures and will thus have the appropriate environment for exothermic reactions by enabling fast quenching of the reaction with near isothermal conditions. Hence also the heat and mass balance in the reactor will be decoupled, which permits the analytical description of the flow in the screening reactor. 

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