Affiliation:
1. Center for Integrative Petroleum Research, King Fahd University of Petroleum and Minerals, Dhahran 31261, Eastern Province, Saudi Arabia
2. Department of Petroleum Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Eastern Province, Saudi Arabia
Abstract
Abstract
Viscosified acids are desired in several oilfield applications such as in acid diversion and acid fracturing operations. The study aimed to delineate the rheological properties of a novel amine type surfactant and viscosified acid-surfactant solutions. The steady shear and dynamic rheological properties were evaluated by varying the surfactant, acid, and salt concentration. Such a study is required to gauge the suitability of the viscosifying agent in acid stimulation jobs. The surfactant solutions without acid showed shear-thinning behavior, whereas those with acid showed a Newtonian plateau over a wide shear rate range before undergoing shear thinning. This means that over a wide shear rate range, the acid-surfactant solutions become independent of applied shear. At low shear rates, the viscosity of the surfactant was higher compared with the surfactant-acid solution. However, at high shear rates, the viscosity of the surfactant was lower compared with the viscosity of the surfactant-acid solution. There was an optimal salt concentration that improved the viscosity and elasticity of the acid-surfactant solutions. Thus, the rheology of the surfactant solution can be improved by adding both acid and salt. The elastic properties of acid-surfactant solutions were also better compared with the elastic properties of pure surfactant. The addition of acid improved the elastic properties of the surfactant solutions. Constant viscosity over a range of shear rate is a suitable application for acid fracturing operations in which the acid leak-off will be minimal due to the high viscosity. Also, brines in most of the carbonate formation consist of high loading of calcium chloride which was found to have a positive effect on the viscosity. Increasing the calcium chloride leads to an increase in viscosity, and then subsequently decreases the viscosity. This shows that the acid and salt concentration plays a role in modifying the rheological properties of the surfactant solutions.
Funder
King Fahd University of Petroleum and Minerals
Subject
Geochemistry and Petrology,Mechanical Engineering,Energy Engineering and Power Technology,Fuel Technology,Renewable Energy, Sustainability and the Environment
Cited by
2 articles.
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