Monte Carlo Risk Assessment of Formation Damage Caused by Asphaltene Deposition

Abstract

Summary Uncertainties regarding the factors that influence asphaltene deposition in porous media (e.g., those resulting from oil composition, rock properties, and rock/fluid interaction) strongly affect the prediction of important variables, such as oil production. Besides, some aspects of these predictions are stochastic processes, such as the aggregation phenomenon of asphaltene precipitates. For this reason, a well-defined output from an asphaltene-deposition model might not be feasible. Instead of this, obtaining the probability distribution of important outputs (e.g., permeability reduction and oil production) should be the objective of rigorous modeling of this phenomenon. This probability distribution would support the design of a risk-based policy for the prevention and mitigation of asphaltene deposition. In this paper we aim to present a new approach to assessing the risk of formation damage caused by asphaltene deposition using Monte Carlo simulations. Using this approach, the probability-distribution function of the permeability reduction was obtained. To connect this information to a parameter more related to economic concepts, the probability distribution of the damage ratio (DR) was also calculated, which is the fraction of production loss caused by formation damage. A hypothetical scenario involving a decision in the asphaltene-prevention policy is presented as an application of the method. A novel approach to model the prevention of asphaltene aggregation using inhibitors has been proposed and successfully applied in this scenario.

Forecasting Asphaltene Deposition Zones at High Temperature and High Pressure via Bubble Point Pressure Analysis

“…The stability of crude oil in the wellbore is a function of temperature and pressure, determining the deposition of asphaltenes and formation of blockages in the wellbore, tubing, and other parts of the surface facility. The production index is seriously affected in the case of asphaltene deposition, lowering revenue and increasing operational costs. − Advanced assessment of risks in asphaltene deposition and implementation of preventive measures can delay the pigging cycle and thus effectively reduce losses caused by oil well plugging.…”