Prediction of Asphaltene Precipitation in an Iranian South Oil Field

Abstract

Asphaltene deposit formation is a severe problem frequently faced during crude oil production that affects the reservoir, production tubing and facilities, depending on the stage where this critical point is reached. This point corresponds to the pressure at which asphaltene particles start to form and directly related to the oil chemical physical stability.Modeling of asphaltene precipitation in the reservoir porous media and in the oilwell tubing of an Iranian south oil field is the purpose of this study. For the reservoir, the modeling technique based on the representation of the precipitated asphaltene as a pure dense phase and division of the heaviest component in the oil into non-precipitating and precipitating components. A set of dummy experimental data was used to tune an equation of state based model that represents the asphaltene as pure component solid. Results of the work show that the chosen model could accurately represent the behavior of the fluids of the reservoir.For the oilwell tubing, a method based on the change of well flow conditions has been used to predict the onset of asphaltene precipitation. The flowing wellhead pressure (FWHP) data from the case study well gathered during the production history of the well. These data generated useful information concerning the well flow conditions that could influence the onset of asphaltene precipitation.

Study of Asphaltene Precipitation and Deposition Phenomenon during WAG Application

“…But in the literature, two proposed structures define the asphaltene molecules as presented in figure 1: the continental (large central aromatic region with small alkyl chains on the periphery) and the archipelago models (smaller aromatic regions linked by bridging alkanes) [37]. On heating, they are not melted but decompose, forming carbon and volatile products above 300 to 400 o C [6,18,38]. On heating, they are not melted but decompose, forming carbon and volatile products above 300 to 400 o C [6,18,38].…”

“…Published data records the molecular weight of Asphaltene in the range of 500 to 500000 [6,36]. Due to the natural tendency of asphaltene molecules to aggregate, the true molecular weight determination is very difficult and takes too much effort.…”

“…Paraffin wax can deposit and form solid crystals due, mostly, to lowering of temperature. There are many papers that have addressed asphaltene problems during primary recovery or CO 2 injection as secondary recovery stage [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The reasons for the asphaltenes deposition can be many factors including variations of temperature, pressure, pH, composition, flow regime, wall effect and electro kinetic phenomena [3,4].…”

Experimental and Modeling Study on Precipitated Asphaltene Biodegradation Process Using Isolated Indigenous Bacteria

“…32 Recently, it was reported that Daedaleopsis sp, isolated from wood-degrading fungi, can degrade asphaltene fraction and dibenzofuran, and in comparison with available studies, this strain could consume more asphaltenes and 88.7% asphaltene biodegradation in crude oil could be attached by this microorganism after 14 days of incubation at 40 °C and pH = 5. 33 The asphaltene precipitation phenomenon in the oil equipment is a serious challenge in the production facilities in the Iranian southwest oilfields, 34,35 and the previous reports showed that there is not a comprehensive study on the possibility of biodegradation of precipitated asphaltenes that considers all culture medium parameters in operational condition and isolated indigenous bacteria from available oilcontaminated samples. Asphaltene biodegradation is a timeconsuming process, and a comprehensive studies on microorganisms' population in the oilfields is required.…”

“…The asphaltene precipitation phenomenon in the oil equipment is a serious challenge in the production facilities in the Iranian southwest oilfields, , and the previous reports showed that there is not a comprehensive study on the possibility of biodegradation of precipitated asphaltenes that considers all culture medium parameters in operational condition and isolated indigenous bacteria from available oil-contaminated samples. Asphaltene biodegradation is a time-consuming process, and a comprehensive studies on microorganisms’ population in the oilfields is required.…”