A Direct Contact Steam Generation (DCSG) solution that injects both steam and hot combustion flue or exhaust gases into the reservoir has the potential to greatly improve the Steam-Oil-Ratio (SOR) for increased oil recovery in heavy and medium reservoirs as well as delivering the added environmental benefits related to reduced water and emissions. Reservoir production is increased by reducing oil viscosity through heat and repressuring the reservoir with the DCSG combustion gases. 

GERI's portable DCSG system was initially piloted in post-CHOPS wells in the Lloydminster area in partnership with oil operators. Each pilot test included both at least one steam and production cycle. For two pilots, a history matched reservoir model was first developed to assess the feasibility and approach for injection and production. A third-party multi-well CHOPS model integrated with CMG STARS simulator was used to forecast reservoir performance by history matching the oil, water and sand production data for the selected test well and several surrounding wells.

The initial test was a huff/puff test followed by a second injection cycle with noticeable production gains in the offset wells resulting in a combined SOR of less than 0.6 compared to typical industry SOR of 3.0 or more. To date over 18,000 barrels of incremental oil production has been realized from the test well and surrounding offset wells. Furthermore, the field trials were able to quantify the environmental benefits of DCSG. In addition to the reduced SOR, DCSG used 13% less water from the incremental combustion steam/water and reduced emissions with 70% of the CO2 sequestered in the formation. DCSG emissions are indirect, with even less emissions if electric compressors are used.  

Based on the results of the DCSG pilots, it is expected that a DCSG technology which injects both steam and hot combustion exhaust gases into the reservoir can be effective in other enhanced oil recovery applications. These applications include using DCSG in Steam Assisted Gravity Drainage (SAGD) fields as well as tight unconventional resource development. 

For tight oil or low permeability reservoirs, DCSG can provide energy and re-pressurize the reservoirs, but also introduce a sweep effect, thereby, increasing recovery. Although the heat impact introduced by steam may not be as great as it is on heavy oil reservoirs, it can reduce oil viscosity and increase oil mobility. For light oil with high paraffin content, waxing could be a production issue. Wax precipitation envelope shows strong dependence on temperature and some dependence on pressure; therefore, DCSG may have a solution by keeping the reservoir temperature and pressure at a level that is away from the wax precipitation range in the reservoir or by reducing the heat sink at the wellbore. 

A history matched multi-well reservoir model was developed on a tight and lighter reservoir, with oil density of 20 API and average permeability of 40 md to assess the feasibility of DCSG. Simulation results showed that even with a very short period of injection (15 – 40 days) of steam plus flue gases, incremental oil recovery for the first year could be 3 to 4 times compared to the no-injection scenario.

The presentation will describe the application of DCSG technology for unconventional resource development and show the simulation scenarios and results. 

PRESENTERS: Brian Kay, P. Eng. Chief Technology Officer, General Energy Recovery Inc.

Location: Zoom Webinar 
Date/Time Information: Friday, February 19, 2021 (from 10h00 to 11h00) – Mountain Time
For more Information and Registration visit CSUR Website (Limited availability)