Relationship between viscosity and biodegradation of oils from the Eastern Venezuelan Basin

Abstract

Venezuela has great reserves of heavy and extra-heavy oils, product of biodegradation, which requires knowledge of the relationship between the viscosity and biodegradation due their important topic for reservoir evaluation and improved oil recovery. In view of its importance, this work studies the relationship between viscosity and biodegradation level in oils from Junín and Ayacucho and Socororo fields from the Eastern Venezuela Basin. Oils from Ayacucho and Socororo present biodegraded oils mixtures, as consequence their API gravities, SARA composition and viscosity is variable. The logarithm of viscosity shows an acceptable correlation with API gravities, and SARA composition. The level of biodegradation determined by the Manco (Modular Analysis and Numerical Classification of Oils) scale does not allow a clear relationship between the biodegradation level and viscosity. However, the MN2 number can be used in the study of crude oil mixtures. The identification of origin and biodegradation level of oils and their relationship with viscosity should be considered for the implementation of adequate production strategies for reservoirs of complex oil composition, to allow the application of suitable methods for the recovery of crude oil, even in nearby wells whose composition and viscosity of the crude oil may be very different.