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Experimental Study from Dissolution of Anorthite and Dark-Colored Femic Minerals in Acetic Acid Solution

Zhang, Wenzheng 1; Yang, Hua 2; Peng, Ping'an 3
1 Institute of Exploration, Development and Research, Xi’an, China.
2 PetroChina Company Limited Changqing Oilfield Branch, Xi'an, China.
3 Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, Guangzhou, China.

An experimental device and flowchart were designed to carry out experiments simulating dissolution of anorthites, pyroxenes and amphiboles in acetic acid solution under a variety of temperature and pressure conditions. Detection of ions and SEM-EDX investigation of the surfaces of particles in the reaction solution during and after experimentation were performed, and the results indicate that anorthite, pyroxenes and amphiboles all show features of erosion and dissolution, with Ca displaying the highest dissolution and Al and Si displaying the lowest dissolution among the major constituent elements. With increase in temperature, the dissolution rates of elements like Ca, Si, and Mg as well as the total dissolution amount of minerals can be remarkably increased, exhibiting positive temperature effect. However, the dissolution trend of Al appears to be special, since at the low temperature stage (50-75oC) its dissolution coefficient is higher than that of Si, exhibiting positive temperature effect, while at the high temperature stage (100-125oC) its dissolution amount turns out to be low or very low, exhibiting negative temperature effect. Precipitation and subsequent separation can mainly account for the low dissolution of Al at high temperature. As a result, complexation of acetic acid appears to be favorable for Al migration during the dissolution of aluminum silicates at the relatively lower temperature rock-forming stage, but cannot account for Al migration during the dissolution of aluminum silicates at the relatively higher temperature rock-forming stage.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009