Downhole Steam Generation

The holy grail for heavy oil recovery technology

Thermal enhanced oil recovery (EOR) is a process in which thick, viscous oil in underground reservoirs is heated in order to allow the oil to better flow towards production wells. The conventional method for heating oil is to inject steam through an injection well, usually located between a series of production wells, causing the heated oil to flow away from the injection well and towards the production wells, where it can then be brought to the surface. While this method has been used successfully for over half a century, it remains inherently inefficient: steam generated in an above-ground boiler will lose 50% of its heat energy in transit. To overcome this inefficiency, the oil and gas industry has made several attempts over the past 30 years to implement downhole steam generation technologies, each time encountering insurmountable mechanical reliability and process control issues.

With our patented and proven Solvent Thermal Resource Innovations Process (STRIP), RII has unlocked the efficiencies of downhole steam generation, and is now in a position to economically produce a vast oil resource with less carbon intensity than conventional methods.


STRIP - Solvent Thermal Resource Innovations Process

Patented, proven downhole steam generation

The STRIP technology generates steam downhole, thereby relocating the products of combustion, mostly carbon dioxide, from the atmosphere to the reservoir. The carbon dioxide will act as a solvent in the reservoir reducing the viscosity of the oil and increasing the pressure of the formation. In combination, the steam and carbon dioxide will significantly increase the flow of oil to the production wells.


The Process

Oxygen and fuel gas are flowed through the STRIP injector and combine at the burner exit to create a flame. Recycled water is flowed around the burner shroud and contacts the flame in the reservoir, creating steam.

The products of the combustion reaction are water and carbon dioxide. The carbon dioxide, which would be vented to the atmosphere in conventional steam injection processes, is instead directly sequestered in the reservoir, where it acts as a solvent to further reduce the viscosity of the oil. Together, the carbon dioxide solvent and the heated steam act to increase the flow of oil to the production wells.



Economic Performance

STRIP is 2/3 the operating cost and 1/3 the initial capital cost of SAGD.

The STRIP technology does not require expensive steam generation and heat management facilities, and because produced water can be reused without recirculation through sensitive boiler systems, water treatment facilities are not necessary. Unlike conventional technologies, steam produced with the STRIP technology does not lose 50% of its heat energy in transit to the reservoir—downhole steam generation is 100% thermally efficient—which greatly reduces energy costs.

Furthermore, existing facilities can easily be converted to STRIP, utilizing existing production wells and production tanks. An existing central vertical well can be converted to a STRIP injection well without the need to replace the well casing or cement.

STRIP Wellhead

  • All gas flows are controlled from the surface, reducing the number of moving components downhole.

STRIP Injection Tubing

  • The STRIP technology utilizes multiple tubing strings inside a well casing to maintain separation between injected water, oxygen and natural gas streams. An additional safety factor is provided by a nitrogen annulus between the oxygen and natural gas, allowing RII to detect any leaks in the oxygen or fuel gas lines by monitoring the pressure of the nitrogen.

STRIP Burner

  • The STRIP burner is installed at the top of the oil reservoir, where a new or existing casing is cut and under-reamed to provide direct contact to the oil-bearing formation. Water is flowed past the burner shroud to provide a cooling effect, after which it contacts the flame within the reservoir to produce steam.


Environmental Benefits

  • Reduced Emissions

    STRIP reduces greenhouse gas emissions in two ways. The first is by utilizing downhole steam generation, which is 100% thermally efficient. This means that unlike conventional technologies, the generated steam does not lose 50% of its heat as it travels hundreds of meters through the well on the way to the oil reservoir. The same heating effects are achieved while using half of the energy.

    This effect is augmented through the direct introduction of CO2, a byproduct of STRIP combustion, which itself acts as a solvent.

    The second way greenhouse gas is reduced is that the combustion reaction that produces steam occurs downhole. Conventional technologies generate steam above ground in large, gas-fired boilers, venting the produced carbon dioxide to the atmosphere. During STRIP operations, a significant amount of the greenhouse gas emissions remain sequestered in the reservoir. The remaining carbon dioxide that is produced from the reservoir can easily be collected and separated due to its purity—an effect of combustion with pure oxygen and not air. In carbon capture processes that collect emissions from air-based combustion, the carbon dioxide is intermixed with 80% nitrogen, requiring an expensive separation process prior to compression and storage. Carbon dioxide produced from STRIP operations can be compressed and stored without the separation step.

    Together, these effects combine to achieve a reduction of greenhouse gas emissions by up to 70% as compared to conventional thermal EOR technologies.

  • Reduced Water Use

    STRIP does not use boilers for steam generation, and therefore does not need to treat produced water before it can be run through sensitive machinery. Brackish, produced water is separated, de-oiled and filtered prior to being pumped back down the injection well. This process also reduces energy requirements for water treatment.

    Nearly 100% of produced water can be re-used.

  • Smaller Surface Footprints

    Compared to conventional thermal oil recovery technologies, STRIP requires no boilers or extensive water treatment facilities, and therefore features a significantly smaller footprint. This minimizes disruptions to the local environment during production, and greatly reduces the cost and complexity of returning the site to its previous state upon project completion.

         

Implementations


CHOPS Conversion

The majority of conventional heavy oil production in Alberta and Saskatchewan is produced via Cold Heavy Oil Production with Sand, or CHOPS, which produces oil from unconsolidated sand reservoirs by coproducing sand, oil, water and gas. This method of “primary” production usually recovers about 5%-10% of the oil in the reservoir. Until now, no method of secondary production has been suitable for re-entering the thousands of CHOPS wells that have been abandoned or suspended. A STRIP injector can be installed in a central CHOPS production well with minimal modifications required, and could achieve incremental oil recovery rates of up to 20-30% in these “depleted” reservoirs.

SAGD Conversion

Existing steam-assisted gravity drainage (SAGD) projects may also be converted to the STRIP process. A STRIP injector is installed at the toe of the upper SAGD horizontal well. The steam produced downhole will flow through the reservoir, using the upper horizontal well as a conduit, heating the oil which will flow down to the lower horizontal production well. Pressure release valves on the upper horizontal well can be used to manage downhole pressures and to control the flows of steam and gasses through the reservoir.



The Market: Heavy Oil and Bitumen Recovery

In the western Canadian provinces of Alberta and Saskatchewan, underground reservoirs of heavy oil and bitumen contain enough oil that if only 30% of it were to be produced, the energy needs of Canada and the United States would be met for over 100 years. However, production of these resources is costly both economically and environmentally, and large amounts of energy must be expended to enable the heavy, highly viscous oil to flow to the surface through production wells.

With the STRIP technology, both the cost and the environmental impact of production is reduced. Where thousands of wells have been suspended or abandoned after producing only 5% of the oil in place, STRIP can be used to cost-effectively restore production from these wells, unlocking millions of barrels for renewed production.



Development History

Location

The STRIP Technology is Conceived and Developed

The STRIP process is conceived by Fred Schneider, followed by a period of significant preliminary development and concept evaluation.

2004-2008
Location

Preliminary Analysis and Computer Simulations

RII enlists several of the world’s foremost research institutions to perform preliminary analysis and computer simulations of the STRIP process, generating valuable information about expected process characteristics and reservoir response, and providing insight into real-world operating strategies. These analyses included burner design and optimization, and preliminary reservoir simulations at Sandia National Laboratories; salt deposition analysis and CO2 sequestration modelling at the University of Rhode Island, and preparations for initial bench-scale testing of optimized burner designs.

2008 - 2010
Location

Bench-Scale Testing

Beginning in 2010, RII conducted several bench-scale tests to test the feasibility and performance of the auto-ignition concept, and to optimize the process controls to maintain flame stability and controlled downhole combustion. The first of these tests included a small scale barrel test, conducted at atmospheric pressure, to confirm the viability of the auto-ignition concept.

2010
Location

Bench-Scale Pressure Testing

Following confirmation of the auto-ignition concept, RII initiated a series of bench-scale tests to evaluate the performance of the STRIP burner design in a pressurized, water filled environment, similar to the conditions that would be encountered within an oil reservoir during STRIP injection.

2011
Location

Full Scale High-Pressure Testing

Above-ground testing culminated in the construction and operation of a full scale, high pressure test stand, capable of simulating reservoir conditions for a STRIP burner. With the success of this test, the STRIP technology was ready for its first full-scale field implementation.

2012
Location

Pilot Project Preparations

Based on the results of the high-pressure tests and computer simulations, RII began the site selection and engineering and design process for the first STRIP pilot project. In 2013, RII, together with Rock Energy Inc. selected the Neilburg reservoir in eastern Saskatchewan as the site of pilot operations.

2012 – 2014
Location

Neilburg STRIP Pilot Project

On March 7, 2014, the first field implementation of the STRIP technology began operations with a successful auto-ignition. RII operated the Neilburg facility for the remainder of 2014, gaining valuable information towards the optimization of the STRIP process and mechanical components for commercial production.

Click here for more information about the Neilburg Pilot Project.

2014