Developing an Integrated Solution to Remove and Inhibit Asphaltene Deposits Through a Laboratory and Field Proven Approach

Abstract

Asphaltene deposits are considered one of the most common issues facing oil fields with low particle stability that can result in loss of well potential, jeopardize wellbore accessibility and cause premature electrical submersible pump (ESP) failures. Traditionally, these deposits are treated with hydrocarbon based solvents, which have low flashpoints, making them hazardous and expensive. The objective of this paper is to provide a comprehensive solution to effectively remove asphaltene and sand fill accumulation that forms in the near wellbore region. This paper will also provide a computational analysis to accurately predict asphaltene precipitation during the production phase for optimized inhibition process. A laboratory approach was implemented to test the effectiveness of different water based solvent types, including aromatic, aliphatic and heteroatom instead of the commonly used hydrocarbon solvents such as xylene to dissolve asphaltene samples collected from the field and placed under anaerobic conditions. A thorough evaluation of fundamental asphaltene properties, including saturates, aromatics, resins and onset pressure, is incorporated into a computational model to understand and accurately predict asphaltene precipitation behavior. The newly developed system offers significant advantages compared to the traditional system in terms of treatment effectiveness, deployment cost and health, safety, and environment (HSE) due to its relatively high flashpoint. The new system utilizes a water based solvent that leaves the formation in a water wet state instead of oil wet, thus creating a barrier layer that will delay asphaltene accumulation and reduce treatment frequency. Field implementation and post-job results utilizing this newly developed water based aromatic solvent will be discussed, including treatment effectiveness to dissolve downhole asphaltene accumulations. Asphaltene inhibition programs have been implemented based on the results acquired from this model and frequent inspection conducted showed no asphaltene deposition over extended production periods. This paper provides a laboratory proven and field tested water based aromatic solvent that is effective in dissolving asphaltene accumulations resulting in improved well potential while reducing the frequency of required treatments thus maximizing productivity. This system is unique as it provides a high flashpoint water/solvent mixture with solvency power often greater than xylene with the additional benefit of leaving the formation strongly water-wet. The developed computational model helped to reduce the treatment frequency resulting in reduced expenses and sustained production.