The performance of steam assisted gravity drainage (SAGD) depends, mainly, upon reservoir characteristics e.g. porosity, permeability and heterogeneity, well bore hydraulics e.g. steam quality, the length and size of wellbores and operational parameters e.g. reservoir and wellbore subcools. However, in reservoirs with underlying bottom water, the performance of SAGD depends on vertical offset between bottom water and producer and pressure differential between bottom water pressure and bottom hole flowing pressure of the producer. Bottom water can act as a heat sink is a known fact, therefore, it can affect project oil rate, steam rate, steam oil ratio (SOR) and, ultimately, the economics of the project. Bottom water can affect heat transfer within reservoir by the injected steam in case of water coning or steam loss to the bottom water. Produced water chlorides concentration (PPM) is an important indication of bottom water coning because of difference in the chemistry of injected steam and bottom water. The chlorides material balance depends upon water saturation in bitumen zone (connate water), formation water chlorides concentration, produced water chlorides concentration and water cut. This study will shed light on significant impact of bottom water coning on SAGD performance through reservoir simulations. It will, also, describe contribution of each of the aforementioned parameters (water saturation in bitumen zone, formation water chlorides concentration, water cut and produced water chlorides concentration), which is very significant, on chlorides PPM material balance for bottom water coning analysis. And it will, also, describe how the safe limit of produced water chlorides PPM (produced water chlorides PPM at which no bottom water is produced) is affected by each of these parameters.

Leismer is the first Statoil operated steam-assisted gravity drainage (SAGD) project in the Athabasca region of Alberta, Canada. Electrical submersible pumping systems (ESPs) are the standard artificial lift method for this project. A field trial was planned for newly developed ESPs rated to 250°C. The increased temperature rating allows operating SAGD chambers at higher pressures, thus providing more operational flexibility for increasing recovery and dealing with common exploitation problems. The field trial required reliable and comprehensive down-hole monitoring, so that thorough ESP performance analysis could be performed under real field conditions. Given the extreme conditions at which ESP systems operate in SAGD, fiber optic pressure and temperature sensors were selected for real-time down-hole monitoring. These sensors were placed at the pump intake, inside the motor and at the discharge. The fiber optic gauges’ performance is comparable to standard SAGD measurement devices, but without some of the disadvantages. The sensing system configuration, ESP interface and installation will be described. This paper will also present the value of real-time ESP monitoring. The pump operation is controlled by continuously history matching performance with well performance software and adjusting parameters to changing down-hole conditions. This ensures the ESPs are run near the best efficiency point. Pump intake sub-cool is controlled to minimize steam flashing occurrence. ESP motor temperature is monitored to boost reliability and run time. Finally, discharge pressure measurement has been used for history matching multiphase flow correlations. This improves ESP performance calculation accuracy in the field’s other wells. Integrating ESP advances with fiber optic measurement has allowed effective local technology qualification under real operating conditions. This project has provided abundant information and knowledge for field-wide production optimization.

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