Screening and Evaluation for Asphaltene Dispersants for Hassi Messaoud Field-Algeria: Laboratory Tests

Abstract

ABSTRACT Precipitation and deposition of organic solids such as asphaltene are very common issues for the petroleum industry globally. The deposition of these solids is considered one of the main issues impacting production losses throughout the pore to refinery chain. Solids induced by asphaltene instability frequently led to well, pipeline and surface equipment plugging, requiring frequent production stops and large -scale and costly operations for removal and to normalize production. Oil producers develop different prevention-/-mitigation strategies depending on reservoir characteristics; In the case of Hassi Messaoud oil field located in Algeria, asphaltene precipitation and deposition is a recurrent issue from the start of production. The most common solutions adopted are physical removal by scraping the production tubing(slickline) and solvent washes of the near-wellbore area and tubing to maintain or recover production. These options are time consuming and costly and have efficiency limitations, so looking for more efficient solutions has become a priority. Chemical solutions are among the techniques being investigated. This paper describes the work done evaluating different chemical dispersants as asphaltene treatment for a Hassi Messaoudi oil field. Many commercial asphaltene dispersants were selected and submitted to the laboratory for evaluation to determine their performance and efficiency at reservoir conditions (instead of stock tank oil conditions) to accurately recreate reservoir challenges for proper chemical evaluation. Work was initiated by performing deposition tests at ambient conditions using various dosages of each chemical, on dead oil samples. Chemicals performance is estimated based on deposition reduction compared to a control with no chemical addition. While these are accepted in industry as quick screening tests, they do not reproduce the complexity of downhole conditions, especially considering the effect of solution gas into asphaltene stability. Therefore, for better understanding of dispersant behavior, laboratory tests were conducted on live oil at specified conditions of temperature, pressure, and shear using Real View®. Prior to that, all dispersants were tested for asphaltene stability at several dosages by a light-scattering technique that combines a solid detection system (SDS) with high-pressure microscopy (HPM).