Toward Common Generalized Phase Diagrams for Asphaltene Containing Hydrocarbon Fluids

摘要

Many hydrocarbon liquids of industrial interest from reservoir fluids to bitumen + diluent mixtures share constituents, from asphaltenes and resins to pentane, and can be classified as asymmetric from a phase behavior perspective. The phase diagrams for these asymmetric fluids are characterized by lenses of four-phase behavior surrounded by three and two regions in both P-x at constant T, and P-T at constant x diagrams. Interest in the phase behavior of reservoir fluids focuses on understanding the impact of phase behavior on flow assrance, risk assessment and other reservoir lfuid management issues as temperatures ranging form 270 K to 470 K and pressures ranging from atmospheric to approx 100 MPa. Until recently, the focus within the heavy oil and bitumen extraction andupgrading sector has been at temperatures greater than 650 K and at pressures ranging from atmospheric to 20 MPa where catalyst coking, line plugging and other refining issues are key applications. Renewed interest in the development of pre-processes for the selective elimination of mineral matter and other undesirable constituents from heavy oil has heightened interest in ROSE like separation processes which have operating conditions and compositions overlapping with those arising in reservoir fluids. Despite this overlap the two literatures remain disparate. Much can be gained by combining achievements from both sectors particularly with respect to the asphaltene deposition issue, a hot topic for both sectors. Qualitative four component phase diagrams can be used to illustrate key features present in the phase diagrams for the entire range of fluids and can provide a sound basis for detailed methematical model development. This concept will be introduced and discussed using examples drawn from both the reservoir fluids and bitumen + diluent mixtures.