Effects of Low Salinity Water Ion Composition on Wettability Alteration in Sandstone Reservoir Rock: A Laboratory Investigation

For various decades, water-flooding mechanisms have been playing important role for improving oil recovery. It was not until recently that researchers discovered that the ionic strength of the brine was substantial. With regard to this, many studies started being published which focused more on the comparison of effects of having high ionic strength and low ionic strength for brine during flooding processes. Low salinity water comprises brine concentration below 5000ppm. At optimum concentration, low salinity water (LSW) when injected into the reservoir enhances the oil recovery considerably. This is attributed to the change of reservoir rock wettability. The process governing these changes are not well understood thus requiring a scrupulous investigation. Moreover there is no a certain fixed salinity range. This study investigates wettability alteration of Berea sandstone rock with brine of different ion composition (NaCl, KCl, MgCl2, CaCl2, and formation water-mostly Mg2+ and Ca2+ ions) and strength (500ppm-6500ppm with exception of formation water which consisted of 13000ppm). For the study, (31) core slabs were extracted from the core plug then saturated with formation water (FW). Next, the slabs underwent aging process in crude oil at ambient pressure and a temperature of 800c. Later, the slabs were removed and immersed in containers with low salinity water at different ionic composition and strength, which is mentioned. The wettability was measured by applying the sessile drop method in certain range of time. According to the results, there have been significantly great change of wettability at Low salinity water in case of KCl was observed. Keywords: ionic strength, wettability, low salinity water, saturation, brine compositio

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved