Changes in operating conditions such as pressure, temperature and composition of the oil can trigger asphaltene deposition during oil recovery operations. It is well known that asphaltene deposition increases operation costs due to cleanup treatments and deferred production.1Enhanced Oil Recovery (EOR) methods can produce changes in operating conditions and therefore, induce the formation of asphaltene deposits. In a previous work,2 it was shown how enhanced oil recovery methods and well treatments can induce changes that affect asphaltene solubility as measured using two recently developed techniques.3,4In the present work, an asphaltene deposit obtained during cleaning of a submersible pump was analyzed. The oilfield was under CO2 flooding as secondary EOR process. The deposit was separated into solubility fractions that were characterized in terms of composition and solubility properties. A comparison with heptane asphaltenes extracted from the crude oil that produced the deposit was carried out and the results indicated that these extracted asphaltenes do not represent the type of asphaltenes present in the solid. Asphaltenes present in the deposit are less soluble and more aromatic indicating a prolong extraction process that may have occurred during the deposit formation in the presence CO2. This phenomenon led to an enrichment of the deposit with less soluble asphaltenes than those found in the heptane extracted asphaltenes coming from the original crude oil.The main goal of this work is to shed some light about the formation of asphaltene deposits and how its composition is related to the materials present in the original crude oil. (1)        Hammami, A.; Ratulowski, J. Precipitation and Deposition of Asphaltenes in Production Systems: A Flow Assurance Overview. In: O.C. Mullins, E. Y. Sheu, A. Hammami, A. G Marshall  (eds.) , Asphaltenes, Heavy Oils and Petroleomics Springer, New York, 2007.(2)        Rogel, E.; Ovalles, C.; Moir, M. Prep. Pap. Am. Chem. Soc. Div. Pet. Chem., 2013, 59,.(3)        Rogel, E.; Ovalles, C.; Moir, M. Energy and Fuels  2010, 24, 4369,(4)        Ovalles, C., Rogel, E., Moir, M., Thomas, L., Pradhan, A. Energy Fuels, 2012, 26, 549.

Comparing asphaltenes: Deposit vs. crude oil

248th National Meeting (2014)

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