The Athabasca Oil Sands is one of the largest oil deposits in the world. It contains 2.75 trillion barrels of bitumen resources, including carbonate deposits (Butler, R. Thermal Recovery of Oil and Bitumen, Prentice-Hall, 1991). The recoverable resource (excluding carbonate deposits) is currently estimated at about 170 billion barrels. (CAPP, The Facts on Oil Sands, November 2010). 20% of these resources is recoverable by mining and the other 80% is recoverable by in-situ Enhanced Oil Recovery (EOR) (CAPP, 2010).
The leading in-situ EOR process to recover bitumen is steam-assisted gravity drainage (SAGD), a steam-only process. Table 1 provides typical production of leading producers in the industry based on SAGD. However, SAGD does have some limitations. Studies indicate that the economical limit for steam transportation, using an insulated pipeline, is about 10 to 15 km (Finn, A., Integration of Nuclear Power with Oil Sands Extraction Projects in Canada, MIT Thesis, June 2007), (Energy Alberta Corporation, Nuclear Energy: Hedging Option for the Oil Sands, CHUA, presentation Nov. 2, 2006), (PAC, Clean Bitumen Technology Action Plan, April 2011).
More specifically, bitumen production is limited because of the following SAGD central plant characteristics: 1) plant life is limited to 40 years at 90% average availability; 2) the available land for SAGD is 30% of the total (either due to reservoir quality, surface access or lease ownership issues); and 3) the average SAGD pattern size is 1000 m×100mth with an average pattern bitumen recovery of 1.5 million barrels (bbls) (411 bbls/day for 10 years). This means that the maximum size for a self-contained bitumen supply, without any satellite plants, based on the above assumptions, is 108,000 bbls/day. Over the assumed 40 year life of a SAGD central plant, the maximum-sized SAGD central plant will recover 1.4 billion barrels of bitumen. In order to fully recover the recoverable resources, there would be a need for about 100 central SAGD maximum sized plants and about 100,000 average SAGD patterns.
One option available to increase bitumen production would be for a large central bitumen producer using SAGD to construct a remote, smaller plant. The SAGD central plant supplies services and some feeds to the remote, preferably smaller SAGD plant as opposed to constructing a new stand-alone (greenfield) SAGD central production plant. This SAGD smaller, remote plant is referred to as a bitumen satellite plant. A bitumen satellite plant is defined as a satellite plant for bitumen production that is “tied” to a central plant by a pipeline corridor. The pipeline corridor supplies a significant amount of input feeds from a central SAGD plant to the satellite SAGD plant, and it returns bitumen (or bitumen and diluent, or bitumen and water) to the central plant.
There are several choices for conveying bitumen and water (produced fluid mix) from a satellite plant to a central plant. The following are examples:
The SAGD satellite plant described above is desirable for the following reasons:
While existing SAGD satellite production plants do have the advantages described above, there is a need for satellite production plants that operate using a more efficient process. By creating SAGDOX satellite production plants, production and efficiency is increased costs are reduced.
The following terms and acronyms are used herein:
CAPP—Canadian Association of Petroleum Producers
SAGD—Steam Assisted Gravity Drainage
SAGDOX—SAGD with Oxygen
PAC—Petroleum Technology Alliance of Canada
NEB—National Energy Board (Canada)
OTSG—Once Through Steam Generator
EOR—Enhanced Oil Recovery
SAGDOX (xx)—SAGDOX with xx % oxygen in the steam/oxygen mix (v/v)
SAGDOX (35)—SAGDOX with 35% oxygen in the steam/oxygen mix (v/v)
ASU—Air Separation Unit
ETOR—Energy to oil ratio (MMBTU/bbl)
SOR—Steam to Oil Ratio (bbl/bbl)
CSS—Cyclic Steam Stimulation
DOE—Department of Energy (USA)
CHUA—Canada Heavy Oil Association
MIT—Mass. Institute of Technology
O/W—Oil in Water (emulsion)
W/O—Water in Oil (emulsion)
HTO—High Temperature Oxidation)(150-300°
bbl-barrel
bbls-barrels
For the purpose of the invention, bitumen is defined as an in situ hydrocarbon with <10 API gravity and >100,000 cp. in-situ viscosity. Preferably for SAGDOX, steam and oxygen are injected separately and continuously. The steam and oxygen rates are controlled to meet oxygen/steam (v/v) ratio targets and to meet energy injection targets. The produced gas removal rate is adjusted to control pattern pressures and to control and/or improve oxygen conformance. The produced fluid (bitumen and water) production rate uses steam trap control, assuming the region around the production well is steam-saturated.
Also for convenience SAGDOX is labeled as SAGDOX (A), where A is the (v/v) percent of oxygen in the oxygen and steam injectant gas). We have assessed our cases in our US patent application US 2013/0098603, herein incorporated by reference, for a range of oxygen concentrations from 5% (v/v) to 50% (v/v).
Further, in the present invention, satellite plant, satellite facility, and satellite site are used interchangeably. Also, central plant, central facility, and central site are used interchangeably.
The present invention relates to a satellite production process for bitumen recovery that either uses SAGDOX or converts an existing SAGD satellite plant to a SAGDOX satellite plant.
SAGDOX is a bitumen enhanced oil recovery (EOR) process. The process may be considered as a hybrid of SAGD and in-situ combustion (ISC). SAGDOX is described, in detail, in US2013/0098603. While similar to SAGD, SAGDOX incorporates extra vertical wells (or segregated injection/production) to inject oxygen into the system and to remove non-condensable combustion gases from the system. SAGDOX adds energy to the bitumen reservoir by direct steam injection and oxygen combustion of residual bitumen. Many of the advantages of the present invention stem from the properties of oxygen versus steam for adding heat to the reservoir.
According to one aspect of the invention, there is provided a SAGDOX satellite system for recovering hydrocarbons, the system comprises a central SAGDOX site, at least one SAGDOX satellite site remote said central SAGDOX site, and a pipeline corridor for communication between the central SAGDOX site and the SAGDOX satellite site, preferably the distance between the central site and satellite site ranges from 9 km to 160 km, more preferably 10 km to 100 km, wherein the satellite system is designed to recover hydrocarbons using a SAGDOX process at the SAGDOX satellite site and transfer recovered hydrocarbons to the central SAGDOX site.
Preferably, the central SAGDOX site comprises:
Preferably, the SAGDOX satellite site comprises:
Preferably, the pipeline corridor comprises:
In a preferred embodiment, while the oxygen, water and natural gas are supplied to the SAGDOX satellite site; oxygen with generated steam is injected into an underground formation; and recovered from the underground formation bitumen emulsion, preferably O/W emulsions, are pumped back to the central site, then the bitumen is separated from the water, and treated water is sent back to the satellite site for steam generation.
Preferably the recovered bitumen emulsion is further combined with a chemical stabilizer or diluent at the SAGDOX satellite site, and the pipeline corridor further comprises a pipe for delivering said chemical stabilizer or diluent to the SAGDOX satellite site.
Preferably the SAGDOX satellite site further comprises a vent gas treating unit for sequestering CO2 and/or other produced gases.
Preferably each central SAGDOX plant has more than one SAGDOX satellite plants attached to it with one or more pipeline corridors.
Preferably at the SAGDOX satellite plant, the oxygen and generated steam are injected into said underground formation in one of the following ways: 1) the oxygen with generated steam are simultaneously injected into the same well; 2) the oxygen with generated steam are simultaneously injected into several wells; 3) or the oxygen and generated steam are separately injected into separated wells for steam and oxygen and the mixture takes place in the underground formation.
Preferably oxygen in the oxygen and generated steam mixture has a concentration in range of 5% to 50% (v/v), preferably 10% to 40% (v/v), more preferably the concentration is about 35% (v/v).
According to another aspect of the invention, there is provided a process of upgrading an existing SAGD facility by transforming it into an SAGDOX satellite system, the process comprising: installation of an oxygen generation unit at the central SAGD facility, providing at least one remotely located SAGDOX satellite site, preferably a plurality of SAGDOX satellite sites, and providing at least one pipeline corridor, preferably a plurality of pipeline corridors, between the central SAGD facility and the SAGDOX satellite site. Preferably said pipeline corridor further comprising additional pipelines for oxygen supply, produced water and natural gas supply; thus increasing the operational area of the original facility for bitumen recovery by minimizing capital cost.
According to yet another aspect of the invention, there is provided a process for recovering bitumen from a satellite bitumen production site and delivering bitumen to a central facility, whereby:
Preferably, the produced fluids (bitumen and water) are conveyed from the satellite bitumen production site to the central facility in a push-water system.
Preferably, the produced fluids (bitumen and water) are conveyed to the central plant as a stabilized emulsion. Preferably said stabilized emulsion comprises a chemical stabilizer, such as ethoxylated nonylphenol, preferably added to the produced fluids (bitumen and water) at the satellite bitumen production site.
Preferably a diluent is blended with the produced fluids (water and bitumen) for transport to the central facility.
Preferably, natural gas or fuel gas is also provided to the satellite bitumen production site, from the central facility by the pipeline corridor, for use as a boiler fuel.
Preferably, electricity is also transported from the central facility to/from the satellite bitumen recovery site.
Preferably, a produced gas (CO2) pipeline is added to convey SAGDOX vent gas from the satellite bitumen recovery site to the central facility.
According to another aspect of the invention an existing SAGD satellite bitumen recovery site with existing steam capacity, is converted to a SAGDOX satellite site, as defined herein, utilizing existing steam capacity at the SAGD satellite bitumen recovery site.
According to another aspect of the invention, produced water is separated at the satellite bitumen recovery site, preferably this water is either treated for boiler use or disposed of on-site, wherein the diluted bitumen, is conveyed back to the central facility generally free from excess water.
More specifically, the present invention, a SAGDOX production satellite plant has the following advantages:
1. The SAGDOX satellite plant is greater than 9 km, more preferably 15 km, distance from SAGDOX central plant because oxygen can be economically pipelined for approximately 100 miles. This is more than 10 times steam's limit of approx. 10 km.
2. SAGDOX satellite site reduces capital expenditures at the satellite site (greenfield) for the pipeline corridor and for the overall project. Most of the expenditures for major process elements are at the central facility. Specifically, pipeline corridor costs for SAGDOX are 22% less; boiler costs can be reduced by 85%.
3. If vent gas (mostly CO2) is captured or sequestered on site, either at satellite plant, central plant, or both), emissions per unit bitumen produced are significantly reduced.
4. As shown in US 2013/0098603, the process efficiency when incorporating SAGDOX satellite site is improved compared to SAGD satellite site. If efficiency is measured as the energy produced (in bitumen) compared to the energy used, on the surface, to produce the energy, then SAGDOX is a much more efficient process than SAGD.
5. Water use is minimized. As shown in US 2013/0098603, if SAGDOX produces connate water, make-up water can be reduced and/or eliminated to the central plant. Specifically, SAGDOX can also produce water directly from combustion and by vaporizing connate water, so that no new make-up water is needed.
6. The steam and oxygen mixture has a preferred oxygen concentration range (5 to 50% (v/v)) This preferred range for SAGDOX has minimum and maximum oxygen/steam ratios, with the following rationale:
So the preferred range for oxygen/steam ratios is 0.05 to 1.00 (v/v) corresponding to a concentration range of 5 to 50% (v/v) of oxygen in the mix.
7. Total capex costs are also less. Per unit energy delivered to the reservoir, oxygen capex is much less than steam and water treating capex.
8. Economies of scale for air separation unit (ASU) oxygen plants at reasonable sizes for SAGDOX satellites have been achieved. For a 25 KBD SAGDOX (35) satellite 2000 tonnes/day of oxygen is needed. This is a nice fit both for the capacity of the satellite and the capacity of the ASU plant.
9. The SAGDOX process of the present invention produces an off-gas in one embodiment that is almost substantially pure CO2. In one embodiment, if this off-gas is captured for sequestration, CO2 emissions in SAGDOX can be much less than SAGD.
10. At first blush, it may appear SAGDOX needs more wells than SAGD—to inject oxygen gas and to remove produced non-condensable gases. However, SAGDOX allows longer horizontal wells to be drilled, by reducing hydraulic limits on horizontal well lengths. So, on a per-unit-volume-of-reservoir basis, SAGDOX well costs can be comparable to or less than SAGD well costs.
11. SAGDOX opex costs are less than SAGD. The wells can be operated longer and reservoirs increased.
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
As seen in
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
Table 2 provides the typical injection gas properties of SAGDOX for the different oxygen concentrations in steam and oxygen mixtures discussed above, according the present invention.
SAGDOX (35) is the preferred embodiment of the process. SAGDOX (35) is depicted in
Comparing
Preferably, the satellite plant is more than 10 km from the central plant, otherwise it would be economic to integrate the satellite and supply steam from a central site. Also, the pipeline corridor, between the satellite site and the central plant site, should contain the following fluids pipelines:
Also preferably, it may be feasible to pipeline produced fluids, without diluent using push water systems as discussed above. Fuel gas may be available from an alternate source, such as local supplies from pipelines or gas wells. For some cases, as listed below, the pipeline corridor may also contain the following fluid pipelines:
Further explaining the advantages of SAGDOX, the cost of the pipeline corridor for SAGDOX satellites is less than SAGD satellites in all embodiments. Assuming installed cost of pipelines is proportional to pipeline diameter, Table 7 summarizes diameters and cumulative diameters for each case assuming a 5 ft/sec velocity (3.4 mph) for liquids and 50 ft/sec for gases at 500 psia (this is within the safe operating region for oxygen in carbon steel pipelines (Sarathi, P. S., In-Situ Combustion Handbook, DOE, 1996). For our preferred case, SAGDOX (35), the capital cost of the pipeline corridor is 22% less than the cost for the SAGD case.
Table 11 highlights a SAGDOX advantage as well. If we pipeline an O/W emulsion from the satellite plant to the central plant, rather than an oil and diluent and water mix, the advantage of the SAGDOX satellite c/w SAGD is even more pronounced.
Even further, assuming a 2000 tonne/day ASU oxygen train, at the central plant, to capture the economy-of-scale for oxygen production, Table 4 shows the minimum satellite project size to capture these savings. The size varies from 61 KBD for SAGDOX (5) to 23 KBD for SAGDOX (50). For our preferred case, SAGDOX (35), the minimum satellite size is 25 KBD.
Referring to Table 3, considerable boiler cost savings when using SAGDOX are highlighted. For example, for a 10 KBD satellite our satellite site boiler capacities and savings are as follows:
If we don't add diluent at the satellite site we may have to add shear to produce an oil in water (O/W) emulsion that will be stable until it reaches the central facility. Alternately, we can add an emulsion stabilizer (surfactant) so that we can pipeline the product safely. The viscosity of O/W emulsions is relatively independent of the oil viscosity and low enough to pipeline directly (
Also, the option with the minimum capex at the satellite site and for the satellite pipeline corridor includes the following elements:
Based on the above, the following can be concluded:
Also discussed above, the SAGDOX option for a new satellite plant has at least one additional pipeline compared to SAGD—the oxygen line to deliver oxygen to the satellite site. But, other lines can have significant reduced capacity (
If we are expanding an existing SAGD satellite, it is particularly advantageous to switch to SAGDOX, because:
Table 10 summarizes the capex item differences at the satellite site and central site when comparing SAGD with SAGDOX, as well as some of the advantages of the present invention.
Other embodiments of the invention will be apparent to a person of ordinary skill in the art and may be employed by a person of ordinary skill in the art without departing from the spirit of the invention.
Number | Date | Country | |
---|---|---|---|
61643538 | May 2012 | US | |
61507196 | Jul 2011 | US | |
61549770 | Oct 2011 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 13543012 | Jul 2012 | US |
Child | 13888874 | US | |
Parent | 13628164 | Sep 2012 | US |
Child | 13543012 | US |