Characterisation and Emulsion Behaviour of Athabasca Extra-Heavy-Oil Produced by SAGD

Abstract

fax 01-972-952-9435. AbstractThe production of extra heavy oil (or bitumen) through the SAGD method (Steam Assisted Gravity Drainage) requires the generation and injection into the reservoir of a great quantity of steam. A typical value of the steam/oil ratio is around 3, which means that a 100,000 bopd development requires the injection of 300,000 bcwepd (barrels of cold water equivalent per day) of steam, and that a corresponding quantity of hot water will be co-produced with the oil. The production of extra heavy oil containing many active components with the tendency to form an emulsion combined with the high water-cut ratio (above 80%) leads to a phase separation process with specific issues. This study considers an extra heavy oil field produced in SAGD in Athabasca.The objective of the study was firstly to characterise the produced fluids and then to analyse their tendency to form an emulsion under controlled hydrodynamic conditions. An innovative technique -Differential Scanning Calorimeter (DSC) -was used to characterise the emulsion. This method is able to define the water-in-oil or reverse emulsion nature and to quantify the water amount without sample dilution. DSC analysis combined with microscopy and image analysis treatments was used to determine the droplet size distribution. Reconstituted emulsions were then formed using a "Dispersion Rig" set-up that allows the simultaneous pumping of crude oil and water through a calibrated restriction in the pipe. The amount of energy dissipated to the fluids systems can be quantified due to the strict control of the hydrodynamic conditions. Consequently a relationship between granulometry distribution of the emulsion and the fixed energy or pressure drop can be established. The main experimental parameters investigated were the oil dilution and water-cut ratios.It is concluded that there is a residual emulsion in extra heavy oil which has a very small average droplet size whatever the temperature and solvent dilution ratio. This small droplet size results in a difficult oil/water separation which is only possible either by addition of large quantities of additives at high temperature and with long residence time and probably by applying an electrostatic field.

Pore-level Investigation of Heavy Oil Recovery Using Steam Assisted Gravity Drainage (SAGD)

“…The topic of "emulsification phenomenon" during the typical SAGD process was covered in the literature based on the experiments conducted using scaled physical models as well as field-scale data [24,[26][27][28][29][30][31]. According to the field-scale trials of the SAGD process, the produced liquid is in the emulsion state composed of mobilized oil and water (either stable or unstable depending on the physicochemical characteristics of the interacting liquids as well as process operating conditions).…”

Application of DSC for Emulsified System Characterization

“…Applications of DSC for characterizing complex emulsified systems are described in several papers [6,[14][15][16][17][18][19][20][21]. We will present here recent examples related to the case of complex emulsions encountered in the oilfield industry.…”

Measurement of Viscosity Alteration for Emulsion and Numerical Simulation on Bitumen Production by SAGD Considering In-situ Emulsification

“…2 shows a typical W/O emulsion produced from SAGD well in Hangingstone, Canada. As evident through some previous experimental studies on this phenomenon [3,6,[8][9][10][11], it has been suggested that W/O emulsions are mostly produced during the SAGD process. Especially, Sasaki et al [8,9] conducted experimental studies of SAGD process by using two-dimensional scaled reservoir model to investigate fluids flow characteristics in the steam chamber.…”