A General Study of Asphaltene Flocculation Prediction at Field Conditions
- Samir G Gharfeh (ConocoPhillips Co.) | Probjot Singh (ConocoPhillips) | Kriangkrai Kraiwattanawong (ConocoPhillips) | David J. Blumer (ConocoPhillips)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- August 2007
- Document Type
- Journal Paper
- 277 - 284
- 2007. Society of Petroleum Engineers
- 4.1.2 Separation and Treating, 5.2 Reservoir Fluid Dynamics, 4.6 Natural Gas, 4.3 Flow Assurance, 5.2.1 Phase Behavior and PVT Measurements, 4.2 Pipelines, Flowlines and Risers, 4.1.5 Processing Equipment, 1.11 Drilling Fluids and Materials, 4.3.1 Hydrates, 1.6 Drilling Operations, 5.3.2 Multiphase Flow, 4.2.3 Materials and Corrosion, 4.3.3 Aspaltenes, 1.8 Formation Damage, 4.5 Offshore Facilities and Subsea Systems
- 4 in the last 30 days
- 1,173 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
A large set of field data have been collected during the last decade related to various facets of asphaltene instability problems at our production facilities. These problems include compatibility of heavy oil with hydrocarbon diluents in a Venezuelan operation, commingling of live oil and condensate in a North Sea production facility, compatibility of drilling mud-base oil, and miscible injectants with reservoir fluids in Alaskan operations. In each of the field cases, significant lab data were generated by titrating the neat dead crude oil, and oil-solvent blends with n-alkanes. The solvents used to study the asphaltene issue were toluene, condensate, and base-oil. We have applied available asphaltene prediction techniques (Heithaus 1960, 1962; Wiehe and Kennedy 2000a, b; Wiehe et al. 2001; Andersen 1999; Wang and Buckley 2001; Wang et al. 2003, 2004; Leontaritis 1998) to explain the field data. None of the models has been found comprehensive enough to explain flocculation at all the conditions, including the flocculation that occurs at ambient conditions in the presence of paraffinic diluents, stability enhancement that occurs upon addition of aromatic solvents, and the instability that occurs in a live fluid because of changes in composition, pressure, and temperature. To handle a complex crude oil system, these models made some simplifying assumptions that enabled them to make the problem manageable. In doing so, they lose some predictive capability. We found there are two forces that need to be accurately captured—dynamics of the alteration of solubility parameter of the hydrocarbon matrix, and change in entropy of mixing—to model the asphaltene behavior. The latter has been either empirically estimated by extrapolating the ambient titration data or neglected in many of the previous models. The basic parameters for our model can be calculated from lab data generated by titrating the dead crude oil, or oil solvent blends with n-alkanes, at different temperatures. So far, this model has been applied to various field conditions in production facilities and has been found successful in matching the field data.
Asphaltenes are generally defined as the fraction that is soluble in aromatic solvents such as benzene or toluene; and insoluble in normal alkanes, such as n-pentane or n-heptane (Speight 1999). Asphaltenes are typically stable in a live fluid at reservoir condition. Once the drilling and production starts, the change in pressure, composition, and temperature can cause asphaltenes to destabilize. Asphaltene precipitation and deposition in production and operation are undesirable situations that are quite expensive to remediate.
The solubility parameter concept first described by J.H. Hildebrand and R.L. Scott (1964) was used as a compatibility indicator, such that if the solubility parameter of any mixture was greater than the solubility parameter at the onset point of precipitation, that mixture was stable—otherwise asphaltene would flocculate..
This paper focuses on the development of a comprehensive asphaltene precipitation model based on the solubility parameter concept. A successful model should be able to predict onset of asphaltene flocculation under any field condition. Several field projects are also included in this paper to show the wide application of the asphaltene precipitation predictor in several different circumstances. For example, asphaltenes can precipitate if an incompatible blend of two or more hydrocarbon liquids are mixed in sales pipeline or in a refinery. Asphaltenes can cause sludge formation and emulsion issues in surface facilities (flow line or separators). Asphaltenes can drop out during depressurization of live oil near wellbore during production or commingling with miscible injectant (MI) in the reservoir during enhanced oil recovery.
|File Size||1 MB||Number of Pages||8|
Andersen, S.I. 1999. Flocculation Onset Titration of Petroleum Asphaltenes.Energy and Fuels 13: 315-322.
ASTM D6703-01. 2001. Standard Test Method for Automated HeithausTitrimetry. American Society for Testing and Materials: West Conshohocken,Pennsylvania.
ASTM D2007-03. 2003. Standard Test Method for Characteristic Groups inRubber Extender and Processing Oils and Other Petroleum-Derived Oils by theClay-Gel Absorption Chromatographic Method. American Society for Testingand Materials: West Conshohocken, Pennsylvania.
ASTM D5186-03. 2003. Standard Test Method for Determination of theAromatic Content and Polynuclear Aromatic Content of Diesel Fuels and AviationTurbine Fuels by Supercritical Fluid Chromatography. American Society forTesting and Materials: West Conshohocken, Pennsylvania.
ASTM D86-05. 2005. Standard Test Method for Distillation of PetroleumProducts at Atmospheric Pressure. American Society for Testing andMaterials: West Conshohocken, Pennsylvania.
ASTM D893-05a. 2005. Standard Test Method for Insolubles in UsedLubricating Oils. American Society for Testing and Materials: WestConshohocken, Pennsylvania.
Buckley, J.S. 1996. Microscopic Investigation of the Onset of AsphaltenePrecipitation. Fuel Sci. Technol. Int. 14: 55-74.
Gharfeh, S.G., Yen, A., Asomaning, A., and Blumer, D. 2004. AsphalteneFlocculation Onset Determinations for Heavy Crude Oil and its Implication.Petroleum Science and Technology 22 (7/8): 1055-72.
Hammami, A., and Raines, M.A. 1999. Paraffin Deposition From Crude Oils:Comparison of Laboratory Results With Field Data. SPEJ 4 (1):9-18. SPE-54021-PA. DOI: 10.2118/54021-PA.
Heithaus, J.J. 1960. Measurement and Significance of Asphaltene Peptization.American Chemical Society. Div. Petrol Chem Preprints 5:A23-A27.
Heithaus, J.J.. 1962. Measurement and Significance of AsphaltenePeptization. J. Inst. Petrol. 48: 45-53.
Hilderbrand, J.H. and Scott, R.L. 1964. The Solubility ofNonElectrolytes. New York City: Dover.
Jewell, D.M., Weber, J.H., Bunger, J.W., Plancher, H., and Latham, D.R.1972. Ion-Exchange, Coordination, and Adsorption Chromatographic Separation ofHeavy-End Petroleum Distillates, Analytical Chemistry 44 (8):1391-1395. DOI: 10.1021/ac60316a003.
Leontaritis, K.J. 1998. Asphaltene Near-Wellbore FormationDamage Modeling. Paper SPE 39446 presented at the SPE Formation DamageControl Conference, Lafayette, Louisiana, 18-19 February. DOI:10.2118/39446-MS.
Speight, J.G. 1999. The Chemistry and Technology of Petroleum. Thirdedition. New York: Marcel Dekker.
Wang, J.X. and Buckley, J.S. 2001. An Experimental Approach toPrediction of Asphaltene Flocculation. Paper SPE 64994 presented at the SPEInternational Symposium on Oilfield Chemistry, Houston, 13-16 February. DOI:10.2118/64994-MS.
Wang, J.X., Buckley, J.S., Burke, N.A., and Creek, J.L. 2003. AnticipatingAsphaltenes Problems Offshore—A Practical Approach. Paper OTC 15254 presentedat the Offshore Technology Conference, Houston, 5-8 May.
Wang, J.X., Buckley, J.S., and Creek, J.L. 2004. Solubility Conditions atthe Onset of Asphaltene Flocculation. Poster presented at the InternationalConference on Petroleum Phase Behaviour and Fouling, Banff, Alberta, Canada,13-17 June.
Wiehe, I.A. and Kennedy, R.J. 2000a. The Oil Compatibility Model and CrudeOil Incompatibility. Energy and Fuels 14: 56-59.
Wiehe, I.A. and Kennedy, R.J. 2000b. Application of the Oil CompatibilityModel to Refinery Streams. Energy and Fuels 14: 60-63.
Wiehe, I.A., Kennedy, R.J., and Dickakian, G. 2001. Fouling of NearlyIncompatible Oils. Energy and Fuels 15: 1057-1058.