Paper Title
The Alteration on Physical Property of Permian Limestone in Northeastern Thailand by using Hydrochloric Acid on Matrix Acidizing

Abstract
The propose of this research is to study on the efficiency of the concentration of hydrochloric (HCl) acid and observe the physical property change of Northeastern Thailand Permian limestone before and after using HCl on the carbonate matrix acidizing. The test was performed on three limestones including Pha Nok Khoa, Nam Mahoran, and Khao Khad formations. These samples were tested with 5%, 10%, and 15% of HCl concentrations at room temperature and ambient condition for 24 hours. The porosity was tested by using the porosimeter. Morphology of microstructure was studied by the Scanning Electron Microscope (SEM) technique. The potential of physical property alteration of Permian limestone depends on the mineral composition such as calcite, clay mineral and quartz. The concentration of 15% HCl is most effective to change the porosity as increase to 8.9%. The most physical property alteration of Permian limestones from dissolve with HCl are Pha Nok Khao, Khao Khad, Nam Mahoran formation, respectively. Keywords - Carbonate, Matrix acidizing, Porosity, Permian limestone.