Evaluation of different parameters affecting the performance of asphaltene controlling chemical additives in crude oils using multiple experimental approaches assisted with image processing technique

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Asphaltene deposition problem in oil field is a major flow assurance problem which is affecting petroleum industry for decades. This issue not only affects sustainable production of crude oil but poses severe impacts to the integrity of production system. There are several methods available for the treatment of asphaltene problem. Among different treatment methods, chemical treatment is the most effective, reliable and flexible method. However, before implementation of this method in field conditions, this technique requires rigorous evaluation of chemical additives in lab environment for final selection of most efficient chemical additive. In this research work, we have applied simultaneous multiple experimented approaches namely; Asphaltene dispersant test and spot test to evaluate chemical additive tendency to reduce asphaltene deposition and enhance asphaltene precipitates dispersion respectively. To improve the interpretation and eliminate uncertainties associated with spot test results, the spot test results were analyzed by image processing tool and precipitation intensities were calculated. Generally, precipitation intensity represents the dispersion ability of chemical additive which in turn is inversely proportional to the deposition. Moreover, the impact of parameters like precipitant type (Molecular Weight of precipitant), volume percentage of precipitant in crude oil, chemical additive dosage and experimental time on precipitation intensities were determined using statistical metric namely relevancy factor. In this study, two precipitants namely; n-pentane and n-heptane were used in two different volume percentages i.e. 75 vol percent and 95 vol percent in three crude oil samples namely; crude oil 1 (CO1), crude oil 2 (CO2) and crude oil 3 (CO3). The final results concluded that chemical additive performance was poor in crude oil 1 as it unable to prevent deposition in most of the conditions. The chemical additive performs equally well for CO2 and CO3 having slightly better results obtained in CO2. Among all studied input parameters, precipitant to crude oil ratio was the most important parameter impacting the performance of chemical additive adversely. The performance of chemical additive was largely negatively affected when precipitant used in crude oil at higher proportion. Secondly, the effect of Molecular weight of precipitant found in strong positive relationship with precipitation intensity the case of CO1 while negligibly negative in case of CO2 and CO3. Precipitation intensities were found to decrease with increasing experimental time and chemical dosage in CO1. However, the positive trend was found in CO2 and CO3 between precipitation intensity with time and chemical dosage. These suggests that chemical additive depend upon the type of crude oil and the underlying operating conditions and cannot be applied for the equal and effective treatment of asphaltene precipitation problem in various crude oils.