A Proactive Approach to Address Solids (Wax and Asphaltene) Precipitation During Hydrocarbon Production

Abstract

Abstract The identification of conditions at which the first crystal of wax or asphaltene appears is the first step toward seeking any remedial options. Various procedures exist in determining the onset of wax and asphaltene precipitation conditions. Among these various processes, acoustic resonance technology (ART) is a newly developed method for the highly accurate non-optical determination of phase transitions in high temperature and pressure reservoir fluids. The acoustic resonance experiments were conducted under a depressurization mode to detect the onset of asphaltene precipitation at a fixed experimental temperature. During the depressurization runs, acoustic features corresponding to the onset of asphaltene precipitation or solid-liquid equilibrium (SLE) conditions were detected as the system pressures were decreased from reservoir conditions. Subsequently, during the same run, the acoustic features were also detected that signified the vapor-liquid (VLE) equilibrium conditions. In addition, isobaric cooling experiments were also conducted to identify the onset of wax precipitation. The isobaric cooling experiments detected the features corresponding to wax precipitation (SLE) conditions. Results defining the SLE and VLE conditions of reservoir crudes containing asphaltenes and wax are extremely promising. Comparison of the VLE data obtained using ART with that obtained using an optical method showed excellent agreement. In addition, comparison of SLE data obtained using ART showed excellent agreement with that obtained using a light-scattering technique where the light scattering technique is applicable.