Asphalt Flocculation and Deposition. V. Phase Behavior in Miscible and Immiscible Injections

Abstract

Asphalt formation and precipitation under primary oil recovery conditions as well as secondary recovery by immiscible gas injection were studied. The crude oils were from a carbonate and highly fractured reservoir. No asphalt precipitated under these conditions. Since the oil reservoir had experienced significant formation damage and plugging of its well's tubing due to asphalt formation and precipitation, the absence of asphalt precipitation in our experiments points to the important influence on asphalt formation of flow of the oil, the streaming potentials arising from the flow, and their interaction with the electrical properties of the asphalt aggregates. Also investigated was asphalt precipitation when an enriched gas was injected into the oil under dynamic (multiple contact) miscibility conditions. Only trace amounts of asphalt precipitated when the dilution ratio R was high enough. However, significant asphalt precipitation occurred in completely miscible injections. For this case, we report exten...