Abstract
Guar based hydraulic fracturing fluids is the most commonly utilized fracturing fluids in oil field. Whereas, it tends to lead to formation damage as a result of adsorption of guar. The adsorption behavior of guar was investigated. The approach for reducing the adsorption was explored in order to achieve the decline of formation damage and improve oil recovery. Firstly, determination method of the guar concentration was obtained via establishing the standard curve. Then, spectrophotometer was used to measure the absorbance of guar before and after adsorption on adsorbent. The obtained absorbance of guar was utilized to determine the adsorption capacity of guar on adsorbent and quantitatively demonstrate the adsorption properties of guar in the reservoir. Finally, the effect of pH, temperature, salts, alcohols and polymers was studied in order to select the condition in favor of reducing the adsorption. The linear relationship between absorbance and concentration can be detected. A simple way to determine the adsorption of guar was established: the adsorption capacity can be determined by absorbance. With increase in pH, the adsorption decreased. There was decrease in adsorption when temperature increased. Monovalent cation inorganic salt resulted in the decrease of adsorption while multivalent cationic inorganic salt and multivalent anionic inorganic salt led to the increase of adsorption. The addition of monobasic alcohol did not affect the adsorption behavior. On the contrary, the addition of ethanediol decreased the adsorption. When adding partially hydrolyzed polyacryamide (HPAM), the adsorption of guar can be decreased. Based on the above results, it can be inferred that the decline of adsorption can be achieved under the condition of high pH, high temperature, monovalent cation inorganic salt, ethanediol and HPAM. The determination approach for guar adsorption was established. The adsorption capacity was determined through the established method. The different influence factors were investigated, and the condition and method were obtained in order to decline the adsorption of guar in formation, thus reducing the formation damage.
