We present a systematic laboratory investigation on the impacts of enhanced oil recovery (EOR) chemicals, i.e., surfactant and polymer, on calcium carbonate scale formation and inhibition. Commonly used inhibitor products, which are based on tri-phosphonate, penta-phosphonate and polyacrylate, are evaluated in the absence and presence of the EOR chemicals. The inhibition efficiency is determined using a modified static bottle procedure and the dynamic tube blocking method. In addition, scale precipitates are characterized with scanning electron microscope and X-ray diffraction techniques. Test results show that the EOR chemicals can have a significant influence on inhibitor performance and scale morphology and polymorphs. These results suggest that new treatment program should be developed beforehand to ensure effective scale control in the chemical EOR project.
Key words: calcium carbonate, scale inhibitor, chemical EOR, morphology, calcite, aragonite, vaterite