Evaluation of the geochemistry in the Arbuckle-Simpson aquifer: Finding flow paths

Scope and method of study. The purpose of this study was to evaluate the historical water chemistry data in the Arbuckle-Simpson aquifer to better understand the flows paths. Historical water chemistry data was gathered from several agencies and publications ranging from 1905 to 2006. Calcium/magnesium ratios were analyzed to determine possible areas of discharge. Other ions were investigated to find out if there were other influences on the calcium and magnesium concentrations. Chloride concentrations were used as a tracer to study the affects of brine mixing with the water chemistry. Cation exchange was also examined to determine if there is any influence on the water chemistry.; Findings and conclusions. Historical water chemistry analyses were found not to contain complete information. Out of the 2,927 samples only 74 contained complete analyses. 359 samples were used to evaluate the water chemistry. Using chloride as a conservative tracer, brine mixing from petroleum reservoirs would account for less than 0.1% of the water composition for 97 percent of the 359 analyses. Equilibrium between ground water and calcite can explain the calcium magnesium ratio for large areas of the Arbuckle and Tishimingo anticlines. This indicates unusual geochemistry in the area that should be studied in greater depth. Cation exchange cannot be excluded as a potential mechanism for altering the water chemistry of the waters of the Arbuckle-Simpson aquifer. However, it does not appear to be a dominant mechanism for the majority of the waters.