Investigation of Changing Pore Topology and Porosity during Matrix Acidizing using Different Chelating Agents

Core flooding acidizing experiments on sandstone/carbonate formation are usually performed in the laboratory to observe different physical phenomena and to design acidizing stimulation jobs for the field. During the tests, some key parameters are analyzed such as pore volume required for breakthrough as well as pressure. Hydrochloric acid (HCl) is commonly used in the carbonate matrix acidizing while Mud acid (HF: HCl) is usually applied during the sandstone acidizing to remove damage around the well bore. However, many problems are associated with the application of these acids, such as fast reaction, corrosion and incompatibility of HCl with some minerals (illite). To overcome these problems, chelating agents (HEDTA, EDTA and GLDA) were used in this research. Colton tight sandstone and Guelph Dolomite core samples were used in this study. The experiments usually are defined in terms of porosity, permeability, dissolution and pore topology. Effluent samples were analyzed to determine dissolved iron, sodium, potassium, calcium and other positive ions using Inductively Coupled Plasma (ICP). Meanwhile Nuclear Magnetic Resonance (NMR) was employed to determine porosity and pore structure of the core sample. Core flood experiments on Berea sandstone cores and dolomite samples with dimensions of 1.5 in × 3 in were conducted at a flow rate of 1 cc/min under 150oF temperature. NMR and porosity analysis concluded that applied chemicals are effective in creating fresh pore spaces. ICP analysis concluded that HEDTA showed good ability to chelate calcium, sodium, magnesium, potassium and iron. It can be established from the analysis that HEDTA can increase more amount of permeability as compared to other chelates

Physico-chemistry of (1,3)-β-glucans

This chapter describes the methods and results of studies into the conformations adopted by (1,3)-β-glucans in solid, solution and native states, and characterization of the physical behavior of (1,3)-β-glucans in dilute solutions, concentrated solutions and gel networks. The physico-chemical properties exhibited by (1,3)-β-glucans are based primarily on the nature and stability of ordered conformations that are present under hydrated conditions. X-ray fiber diffraction analysis has shown unambiguously that a triple helix can be formed under both anhydrous and hydrated solid state conditions for linear (1,3)-β-glucans; similar diffraction behavior for side-chain-substituted (1,3)-β-glucans suggests a similar triple helical form with reduced lateral aggregation of glucan backbones due to the presence of side chains. Solid state 13C nuclear magnetic resonance (NMR) provides evidence that triple helical conformations are present within gels and some native forms of (1,3)-β-glucans. Light scattering, electron microscopy and atomic force microscopy data show the presence of triple helices for a range of substituted (1,3)-β-glucans in dilute aqueous solution, and are consistent with single-chain forms in solutions of alkali and dimethyl sulfoxide (DMSO)

Kinetics of starch digestion and functional properties of twin-screw extruded sorghum

The time-course of starch digestion in twin-screw extruded milled sorghum grain was investigated using an in-vitro procedure based on glucometry. The sorghum grains were hammer-milled, and extruded at three levels each of moisture and screw speed. Irrespective of the extrusion conditions, extruded and non-extruded milled sorghum grain exhibited monophasic digestograms, and the modified first-order kinetic and Peleg models adequately described the digestograms. Extrusion increased the rate of digestion by about ten times compared with non-extrudates. Starch gelatinisation varied in the extrudates, and microscopy revealed a mixture of raw, gelatinised and destructured starch and protein components in the extrudates. Starch digestion parameters significantly (p < 0.05) correlated with extruder response and various functional properties of the extrudates. Extrusion conditions for maximum starch gelatinisation in milled sorghum grain for fastest digestion as an efficient animal feed were interpolated, as well as the conditions for directly-expanded extrudates with potential for human food, where minimum starch digestion is desired. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved