Computational Methods in Engineering and Science

In this work, the formation of clay deposits in sedimentary basins and the transformation of their mineral composition, microstructure and water content in the course of lithogenesis are treated in relation to the occurrence of oil and gas deposits.Major topics discussed in this book comprise the revealing of the main regularities in the variation of physical, mechanical, and seepage properties of clay in relation to its occurrence depth. In addition, a close relationship is demonstrated between clay deposit transformations and clay composition, thermodynamic conditions, pore space, structural bonds and geochemical composition of porous solutions. Facies conditions of clay seal development are also analysed and the relation between the cyclic structure of sedimentary massifs and sedimentary basin evolution is described. To this end, seven facies types of clay seals that differed with regard to composition, formation conditions, and screening properties have been distinguished by facies analysis of more than forty sedimentary oil-and-gas bearing basins within the former USSR territory. Also the correlation between clay properties and clay occurrence depth per seal type and the main factors controlling intensification and degradation of screeningproperties are described and it is shown that the maximum clay screening effect depth is an important indicator in the occurrence of oil and gas deposits.Information on modelling of the structure, properties and transformations of clay seals at various depths is included in the final part of the work. In this section, also data like clay porosity graphs and strength variation at different lithogenesis stages are provided and the prediction of screening properties of clay seals with the help of software that was developed by the authors is treated.