Environmental protection is becoming a primary objective when choosing processes and technologies for treating oily waters resulting from hydrocarbon production. The focus of treating oily waters is to eliminate contaminants from effluents before discharging them into the receiving environment while adhering to discharge standards. Our work aims to analyze the treatment process for oily waters in the API unit of the North Industrial Center (CINA), which involves a physical–chemical treatment using activated silica and Kurifix. The study aims to improve the treatment process used for oily water treatment to ensure water conservation for reuse. To enhance the CINA-HMD oily water treatment process, we created coagulants with different doses (C1–C6) using sodium silicate, activated silicate (sodium silicate + sulfuric acid), distilled water, Kurifix, and an oxygen scavenger while measuring pH, HC (hydrocarbon), and SS (suspended solids) levels. Coagulation and flocculation processes were used to remove suspended solids and hydrocarbons from the water. The results show that the coagulant used reduces suspended matter and hydrocarbon content and increases pH. The best treatment is achieved with a coagulant prepared with distilled water, 5% sodium silicate, and 2% sulfuric acid. The optimal dose of coagulant is 16 ppm. Automatic dosing provides better efficiency than manual dosing. The study recommends continuous verification of chemical preparation and injection, periodic cleaning of settling tanks, and monitoring of oily water entering the station.