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AN EXPERIMENTAL STUDY OF THE EFFECT OF PARAFFINIC SOLVENTS ON THE ONSET AND BULK PRECIPITATION OF ASPHALTENES

1995; Taylor & Francis; Volume: 13; Issue: 9 Linguagem: Inglês

10.1080/08843759508947730

2331-0480

Ahmed Hammami, Denise Chang-Yen, John A. Nighswander, Ellen Stange,

Enhanced Oil Recovery Techniques

ABSTRACT Asphaltene onset concentration and bulk deposition were measured for a typical live reservoir oil titrated with n-C6H14, n-C5H12, n-C4H10, C3H8, C2H6, CH4 and CO2 at 100° C (212 ° F) and 29.9 MPa (4340 psia). The concentration of titrant at asphaltene onset was observed to decrease approximately in a linear fashion with decreasing molecular weight of the paraffinic solvent; CH4 did not induce any asphaltene precipitation. Bulk deposition experiments were performed using a solvent: oil volume ratio of 10:1; the results indicated that the weight percent of asphaltenes precipitated increased exponentially with decreasing molecular weight of the paraffinic solvents. More importantly, the asphaltene molecular weight showed a maximum for n-C4H10 precipitated asphaltenes. Possible explanations for this unusual result are presented.