Application of nonionic surfactant nonylphenol to control acid stimulation in carbonate matrix

Abstract One of the main challenges of the acid stimulation process in carbonate matrix is the formation of a dominant pattern wormhole, which is generally not obtained with the application of concentrated hydrochloric acid. Due to its high reactivity, the calcite will be consumed around the oil well, thus not forming the appropriate extension channels to reach the desired breakthrough. From this context, this work aimed to evaluate the behavior of the surfactant Nonylphenol 100 EO in delaying the reaction between HCl 15% and the carbonate in order to form the desired wormhole, where little acid is consumed to reach breakthrough. For this, flow tests were performed in porous medium at different injection rates (0.5, 2 and 5 mL/min), in which it was possible to determine the PVBt curves of HCl and HCl with 10% of the surfactant. The wormhole patterns obtained were identified through computed tomography images. It was noticed that the presence of the surfactant in the acid solution provided the reaction delay, which consequently reduced the values of PVBt in all flow rates. Computed tomography images showed a dominant pattern in all injection rates with the presence of surfactant, which was not seen with pure HCl.