This work relates generally to the use of surfactants in oil field acidizing operations to reduce emulsion and sludge formation in such operations. The demulsifier and antisludge are two of the most important additives in oil well acidizing. During oil well acidizing, an antisludge agent prevents asphaltene aggregation (sludge formation), and a demulsifier agent breaks the oil film in acid emulsion. Most of the antisludge agents presented before were anionic surfactants, whereas demulsifier agents were cationic surfactants. But in this study we have introduced a cationic surfactant as an antisludge and a demulsifier agent simultaneously. This cationic surfactant is a quaternary ammonium compound, didecyl dimethyl ammonium chloride (QAM), compared with dodecyl benzene sulfonic acid (DDBSA), which is introduced as a strong antisludge in literature, and NE32, which is a commercial antisludge agent. Then, QAM is compared with NE13, which is a commercial demulsifier. The experiments are conducted based on API RP 42 standard test for both agents. The results show that the QAM is a multiobjective additive which has antisludge and demulsifier properties simultaneously. However, the QAM is shown to be more effective than DDBSA and NE32 as an antisludge agent but less effective than NE13 as a demulsifier.