Giovanni Brighenti

Specific Surface and Fluid Transport in Sandstones Through NMR Studies

Recent nuclear magnetic resonance (NMR) studies in water-saturated porous media showed that magnetic resonance relaxation of {sup 1}H nuclei is a powerful tool for studying the interplay between geometry and fluid transport. Proper combinations of spin-lattice relaxation lifetime, T{sub 1}, and porosity allow permeability to be predicted. T{sub 1}, as defined here, provides a bridge between structural and transport properties because it can be viewed as a dynamically weighted (by diffusion) version of the specific surface. In this paper, the authors probe this role of T{sub 1} for a suite of clean sandstone samples in which, besides permeability and porosity, specific surface by mercury porosimetry and the formation resistivity factor (FRF) also have been measured. The authors studied the correlations among these properties and found that the ability of T{sub 1} to estimate permeability is a result of its linear dependence on the PV-to-surface ratio, V{sub p}/S.

Chapter 5 Subsidence studies in Italy

Publisher Summary This chapter presents the subsidence studies in Italy. Because of its geology, Italy is subjected to the phenomena of natural land subsidence due to the slow compaction of the sediments and due to volcanism and earthquakes. In the vicinity of coastal areas, the effects of subsidence are aggravated by eustatic phenomena. Despite all the problems, the natural subsidence is less than the anthropogenic subsidence. The chapter discusses the effects of the anthropogenic type of subsidence. Subsidence has caused, besides retreats of the coastline, serious damage to the industrial area, frequently flooded with water during sea storms, and to harbor infrastructures, some of which are now under sea level. This made it necessary to build protection walls and to raise the quays and to rearrange accessory infrastructures. The subsidence is primarily caused by humans, a major role being played by groundwater withdrawals. Significant subsidence occurred during the period of maximum exploitation, sometimes causing local land sinking. Subsidence, however, is very difficult to evaluate because any previous reference high-precision levelling is lacking.