Additives for steam-recovery of bitumen

Abstract

The present invention relates to in-situ bitumen recovery from an oil sand reservoir. Steam at 200℃ to 280℃ is injected into the reservoir with select alkanolamines that (1) have a vapor pressure (Pv) of at least 0.001 mm Hg at 20℃, and (2) have a pKa value of at least 9.0, and (3) have an HLB-Factor of at least 0.5. The steam / alkanolamine blend contains less than 25 parts-per-hundred of capped glycol ethers, based on the weight of alkanolamines.

Description

ADDITIVES FOR STEAM-RECOVERY OF BITUMENTECHNICAL FIELD

[0001] This application relates to the field of oilfield services.BACKGROUND

[0002] Bitumen and heavy oil (collectively called “high viscosity petroleum” or “HVP” in this document) are viscous petroleum mixtures that are often too viscous to flow readily. Oil sands often contain HVP mixed with sand, clay, and other inorganic materials. Deposits of oil sands are found around the world, including Canada, Venezuela, and the United States.

[0003] A common group of processes to recover HVP from deep wells uses steam injection to heat the HVP and reduce its viscosity, so that it can flow to a production well and be pumped to the surface. These “steam recovery processes” include cyclic steam stimulation (CSS), steam flooding, and steam assisted gravity drainage (SAGD).

[0004] Cyclic steam stimulation (CSS) uses a single well for both injection of steam and recovery of HVP. Steam is injected into the well at a temperature of 250°C to 400°C over a period of days to heat the HVP and decrease its viscosity. The well is allowed to equilibrate for days or weeks, allowing the heated HVP and condensed steam to flow back to the well. Then HVP mixed with condensed steam is pumped to the surface. The process is then repeated. Unfortunately, the CSS process typically results in only 20 to 25 percent recovery of the available HVP.

[0005] Steam flooding uses two vertical wells separated from each other with the target oil sand reservoir between them. A production well is drilled at one end of a reservoir to the level of the oil sands, and an injection well is drilled at the opposite side of the reservoir. Steam is injected into the injection well. The steam heats the HVP and reduces its viscosity, and steam pressure pushes the HVP toward the production well, where it is recovered and pumped to the surface. Steam flooding is commonly used to obtain additional production from an oil sand reservoir after CSS. Typical recovery of the available HVP from steam flooding is about 50 percent.

[0006] Steam assisted gravity drainage (SAGD) uses two different two horizontal wells. A production well is drilled horizontally below oil sands in a reservoir, and an injection well is drilled horizontally above the production well, such as about 5 meters above. Groups of these wells may extend through a reservoir for kilometers in multiple directions. Steam is injected into the injection well. The steam heats and reduces the viscosity of HVP above, to the sides of and below the injection well. Gravity causes the HVP to flow down to the production well, where it is recovered and pumped to the surface. Typical recovery of the available HVP is 40 to 60 percent.

[0007] The steam recovery processes often produce an emulsified mixture of HVP and water. Demulsifiers are used to separate the emulsion into aqueous and organic phases, which can be separated by decanting. The water is cleaned and re-used to make more steam. The HVP is sent for further processing and refinement.

[0008] It is desirable to maximize the recovery of HVP, but steam recovery processes recover only a fraction of the HVP in the reservoir. Thus, there remains a need for efficient and cost-effective methods to increase the recovery of HVP from oil sands. It is known to increase recovery by adding amines, alkanolamines, or inorganic bases to the steam in the steam recovery processes. It is desirable to identify optimized additives that can be used in the steam recovery processes.

[0009] PCT Publication WO 2015 / 143,034 describes the pKa value of amines used in steam recovery processes. The “pKa value” is the negative base- 10 logarithmic value of the acid dissociation constant (Ka) of the amine.

[0010] PCT Publication WO 2018 / 208,438 introduces the “HLB-Factor” as a calculated value that can characterize alkanolamines used in stream recovery processes. The HLB-Factor of an alkanolamine molecule is calculated using Equation 1 :(1) HLB-faCtOr = HLB (longest chain) + 0.5 X HLB (second longest chain) + 0.25 X HLB (third longest chain) wherein the longest chain, second longest chain, and third longest chain are each moieties pendant from the amine nitrogen, and HLB (chain) means the sum of the Davies' group contributions for that particular chain, not including the nitrogen atom. Davies' HLB group contributions are well known in the literature. The Davies' group contribution for -CH-, -CH2-, and -CH3 groups is -0.475, the Davies’ group contribution for a phenyl group is -1.662, and the Davies' group contribution for the -OH group is 1.9. PCT Publication WO 2018 / 208,438 suggests that alkanolamines used in steam recovery processes should have an HLB- Factor from 0.5 to -2.2.SUMMARY

[0011] The present invention is a process for recovery of bitumen or heavy oil (collectively called “high viscosity petroleum” or “HVP”) from an underground reservoir that contains HVP, comprising the steps of: a) injecting into the reservoir a steam / alkanolamine blend that comprises: i. steam at a temperature from 200°C to 280°C; and ii. at least 100 parts-per-million-by-weight (ppmw) of one or more alkanolamines, called “select alkanolamines,” that (1) have a vapor pressure (Pv) of at least 0.001 mm Hg at 20°C, and (2) have a (pKa value) of at least 9.0, and (3) have an HLB-Factor above 0.5, andiii. less than 25 parts-per-hundred-by-weight (pphw) of glycol ether that is capped by ethylene oxide or propylene oxide (“capped glycol ethers”), based on the combined weights of the alkanolamine mixture and capped glycol ethers, under conditions such that HVP flows to a production well; and b) recovering the HVP from the production well.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic of the test apparatus used in the Examples. The test apparatus simulates in-situ recovery of bitumen from oil sands.DETAILED DESCRIPTION

[0013] This invention relates to in-situ recovery of high viscosity petroleum (HVP) from an oil sand reservoir by a steam recovery process, such as CSS, steam flooding or SAGD.

[0014] The term “steam” used herein includes superheated steam, saturated steam, and less than 100 percent quality steam. For purposes of clarity, the term “less than 100 percent quality steam” refers to steam having a liquid water phase present. Steam quality is defined as the weight percent of dry steam (vapor only) contained in a unit weight of a steam-liquid mixture. “Saturated steam” is used synonymously with “100 percent quality steam.” “Superheated steam” is steam which has been heated above the vapor-liquid equilibrium point. In some embodiments, superheated steam is between 5 to 50°C above the vapor-liquid equilibrium temperature.

[0015] In this invention, the steam temperature is at least 200°C and at most 280°C. In some embodiments, the steam temperature is at least 205 °C or at least 210°C or at least 215°C or at least 220°C or more than 220°C or at least 225°C. In some embodiments, the steam has a temperature of at most 275°C or at most 270°C or at most 265°C or at most 260°C or at most 255°C or at most 250°C or at most 245°C or at most 240°C or at most 235°C or at most 230°C or at most 225°C. Steam temperature is measured at the point of injection into the injection well. Steam temperature decreases when the steam encounters the environment of the reservoir.

[0016] In some embodiments, the steam has a pressure of at least 4 bar or at least 10 bar or at least 15 bar. In some embodiments, the steam has a pressure of at most 86 bar or at most 47 bar or at most 40 bar.

[0017] In the steam recovery process, steam is injected through an injection well into the reservoir. The steam heats the HVP and reduces its viscosity. In the process, the steam condenses to water. A mixture of the HVP and water flows to a production well, where it is recovered and pumped to the surface. In some embodiments, the mixture is recovered as an emulsion.

[0018] As previously described, in a CSS process, a single well serves as both injection well and production well. Steam is injected into the well. The well is allowed to equilibrate while HVP and water are in contact, and heat transfer occurs. Then the HVP / water mixture is pumped to the surface using the same well. In some embodiments, steam injections are maintained for at least 1 day or at least 2 days or at least 3 days or at least 4 days or at least 5 days or at least 6 days or at least 7 days or at least 8 days or at least 9 days. In some embodiments, steam injections are maintained for at most 21 days or at most 18 days or at most 15 days or at most 14 days or at most 13 days or at most 12 days.

[0019] As previously described, in a steam flooding or SAGD process, steam is injected through an injection well. The force of the steam (in steam flooding) or the force of gravity (in SAGD) brings the softened HVP in a mixture with water to a separate production well. Steam may be injected continuously into the injection well, or steam may be injected periodically with rest times between injections. In some embodiments, the rate of steam injection is managed to maintain a constant desired pressure. In some embodiments, steam is injected at a constant rate, which may be based on the available capacity of steam. In some embodiments of steam flooding, the rate of steam injection is sufficient to provide an advance through the formation of from 1 to 3 feet / day. In some embodiments of steam flooding or SAGD, injection of steam may be simultaneous or alternated with injection of other materials, such as water, carbon dioxide, hydrocarbon or nitrogen.

[0020] Equipment for injecting steam and the alkanolamines into the injection well is known and commercially available. In some embodiments, equipment that is in contact with alkanolamines is made of corrosion-resistant materials, such as stainless steel. In some embodiments, ordinary carbon steel is acceptable.

[0021] In this invention, the steam is part of a steam / alkanolamine blend that comprises, in addition to steam, one or more alkanolamines. In some embodiments, the steam / alkanolamine blend comprises a single alkanolamine. In some embodiments, the steam / alkanolamine blend comprises no more than 8 different alkanolamines or no more than 6 different alkanolamines or no more than 5 different alkanolamines or no more than 4 different alkanolamines or no more than 3 different alkanolamines or no more than 2 different alkanolamines.

[0022] Each alkanolamine comprises at least one amine group and at least one hydroxyl group linked by at least one alkyl group. Some embodiments of the alkanolamines are represented by Formula 1 :wherein:• R1is an alkyl group and• R2and R3are each individually selected from hydrogen, alkyl moieties, alkanol moieties which comprise an alkyl group with a pendant or terminal hydroxyl group, and alkylamine moieties which comprise an alkyl group with a pendant or terminal amine group.

[0023] At least 100 parts-per-million-by-weight (ppmw) of the steam / alkanolamine blend comprises select alkanolamines that meet the following criteria:1. The vapor pressure of the select alkanolamines at 20°C is at least 0.001 mm Hg; and2. The pKa value of the select alkanolamines is at least 9.0; and3. The HLB-Factor of the select alkanolamines is above 0.5.In addition, the steam / alkanolamine blend may optionally comprise alkanolamines that are not select alkanolamines. In some embodiments, the select alkanolamines make up at least 10 weight percent of alkanolamines in the steam / alkanolamine blend or at least 20 weight percent or at least 30 weight percent or at least 40 weight percent or at least 50 weight percent or at least 60 weight percent or at least 70 weight percent or at least 80 weight percent or at least 90 weight percent. In some embodiments, the select alkanolamines are up to 100 weight percent of alkanolamines in the steam / alkanolamine blend.

[0024] In some embodiments, the vapor pressure (Pv) of the select alkanolamines at 20°C is at least 0.005 mm Hg or at least 0.01 mm Hg or at least 0.02 mm Hg or at least 0.05 mm Hg or at least 0.08 mm Hg or at least 0.10 mm Hg or at least 0.15 mm Hg or at least 0.20 mm Hg or at least 0.25 mm Hg or at least 0.30 mm Hg or at least 0.35 mm Hg or at least 0.40 mm Hg or at least 0.45 mm Hg or at least 0.48 mm Hg. In some embodiments, the vapor pressure (Pv) of the select alkanolamines at 20°C is at most 10 mmHg or at most 5 mmHg or at most 4 mmHg or at most 3 mmHg or at most 2 mmHg or at most 1 mmHg or at most 0.8 mmHg or at most 0.6 mmHg.

[0025] In some embodiments, the normal boiling point (at 1 atm pressure) of the select alkanolamines is at least 100°C or at least 110°C or at least 120°C or at least 130°C or more than 135°C or at least 140°C or at least 150°C or at least 160°C or at least 165 °C or at least 170°C. In some embodiments, the normal boiling point (at 1 atm pressure) of the select alkanolamines is below 240°C or at most 230°C or at most 220°C or at most 210°C or at most 200°C or at most 190°C or at most 180°C or at most 175°C or at most 170°C.

[0026] In some embodiments, the pKa value of the select alkanolamines is at least 9.1 or at least 9.2 or at least 9.3 or at least 9.4 or at least 9.5. In some embodiments, the pKa value of the select alkanolamines is at most 11.00 or at most 10.90 or at most 10.80 or at most 10.70 or at most 10.60 or at most 10.50 or atmost 10.40 or at most 10.30 or at most 10.20 or at most 10.10 or at most 10.00 or at most 9.95 or at most 9.90.

[0027] In some embodiments, the HLB-Factor of the select alkanolamines is at least 0.52 or at least 0.54 or at least 0.56 or at least 0.58 or at least 0.59 or at least 0.60 or at least 0.65 or at least 0.70 or at least 0.75 or at least 0.80 or at least 0.85 or at least 0.90 or at least 0.95. In some embodiments, the HLB-Factor of the select alkanolamines is at most 1.3 or at most 1.2 or at most 1. 1 or at most 1.05 or at most 1.00 or at most 0.95.

[0028] In some embodiments, each select alkanolamine is individually soluble in water up to at least 1000 ppmw or at least 2000 ppmw or at least 3000 ppmw or at least 4000 ppmw or at least 5000 ppmw or at least 8000 ppmw or at least 10,000 ppmw. In some embodiments, one or more of the alkanolamines is completely miscible with water. Larger alkyl groups in R1, R2, and R3can reduce solubility in water, and hydroxyl or amine groups in R1, R2, and R3can increase solubility in water.

[0029] In some embodiments, each select alkanolamine individually has a molecular weight of at least 60 Da. In some embodiments, each alkanolamine individually has a molecular weight of at most 200 Da or at most 180 Da or at most 160 Da or at most 140 Da or at most 130 Da or at most 120 Da.

[0030] In some select alkanolamines, R2and R3are each hydrogen, so the amine is a primary amine and the alkanolamine is a monoalkanolamine such as monoethanolamine. In some select alkanolamines, R2is hydrogen, and R3is an alkyl moiety or an alkanol moiety, so the amine is a secondary amine. In some alkanolamines, R2and R3are each individually an alkyl moiety or an alkanol moiety, so the amine is a tertiary amine.

[0031] In some select alkanolamines, one of R2and R3is an alkanol moiety, so the select alkanolamine is a dialkanolamine. In some embodiments, both R2and R3are alkanol moieties, so the alkanolamine is a tri alkanolamine.

[0032] Alkyl groups in R1independently comprise at least 2 carbon atoms. When R2and R3comprise alkyl groups, the alkyl groups in R2and R3independently comprise at least 1 carbon atom. In some alkanolamines, alkyl groups in R1, R2, and R3independently comprise at most 5 carbon atoms or at most 4 carbon atoms or at most 3 carbon atoms or at most 2 carbon atoms.

[0033] In some select alkanolamines, alkyl moieties in R2and R3are individually selected from methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, or from methyl, ethyl, propyl and butyl groups. In some embodiments, alkyl moieties in R2and R3are methyl groups. In some select alkanolamines, alkyl moieties in R2and R3are ethyl groups. In some select alkanolamines, alkyl moieties in R1are individually selected from ethyl, propyl, butyl, pentyl, and hexyl groups, or from ethyl, propyl and butyl groups. In some embodiments, alkyl moieties in R1are ethyl groups.

[0034] In some select alkanolamines, the amine moiety is not bonded to the alkanolamine groups at the same carbon atom as the hydroxyl moiety (the 1 -position). In some select alkanolamines, the amine moiety is bonded to the alkanol group in the 2-position with respect to the hydroxyl moiety. In some select alkanolamines, the amine moiety is bonded to the alkanol group is in the 3-position with respect to the hydroxyl moiety. In some select alkanolamines, die hydroxyl moiety in die alkanol group is in die terminal position with respect to the amine moiety. In some select alkanolamines, alkanol moieties (in HO-R1, R2and / or R3) are individually selected from 2-hydroxyethyl (-CH2-CH2-OH), 2-hydroxypropyl (-CH2- CH(CH3)-OH) or 3-hydroxypropyl (-CH2-CH2-CH2-OH) moieties.

[0035] Examples of select alkanolamines include monoethanolamine (2-aminoethanol, MEA), N-methyl ethanolamine (NMEA), and N,N-dimethylethanolamine (DMEA). In some embodiments, the select alkanolamines comprise at least 50 weight percent MEA or at least 60 weight percent or at least 70 weight percent or at least 80 weight percent or at least 90 weight percent or up to 100 weight percent. In some embodiments, the select alkanolamines comprise at least 50 weight percent NMEA or at least 60 weight percent or at least 70 weight percent or at least 80 weight percent or at least 90 weight percent or up to 100 weight percent. In some embodiments, the select alkanolamines comprise at least 50 weight percent DMEA or at least 60 weight percent or at least 70 weight percent or at least 80 weight percent or at least 90 weight percent or up to 100 weight percent.

[0036] The select alkanolamines of this invention may accept a proton from water to form ionized equivalents when they are mixed with water or steam. The description of alkanolamines in this document includes and applies with equal force to the ionized equivalents.

[0037] The select alkanolamines may be added to the steam neat or as a concentrate. If added as a concentrate, it may be added as a 1 to 99 weight percent solution in water. In some embodiments, the concentrate contains at least 5 weight percent of the select alkanolamines or at least 10 weight percent or at least 15 weight percent or at least 20 weight percent or at least 25 weight percent. In some embodiments, the concentrate contains at most 90 weight percent of the select alkanolamines or at most 80 weight percent or at most 70 weight percent or at most 60 weight percent or at most 50 weight percent. In some embodiments, the select alkanolamines are substantially volatilized and carried into the reservoir as an aerosol or mist, in order to maximize the amount of alkanolamines traveling with the steam into the reservoir.

[0038] The steam / alkanolamine blend contains at least 100 parts-per-million-by-weight (ppmw) of the select alkanolamines. In some embodiments, the steam / alkanolamine blend contains at least 200 parts-per- million-by-weight (ppmw) of the select alkanolamines or at least 250 ppmw or at least 400 ppmw or at least 500 ppmw or at least 750 ppmw or at least 1000 ppmw. In some embodiments, the steam / alkanolamineblend contains at most 20,000 ppmw of the select alkanolamines, or at most 15,000 ppmw or at most 10,000 ppmw or at most 8000 ppmw or at most 6000 ppmw or at most 5000 ppmw.

[0039] We hypothesize, without intending to be bound, that the select alkanolamines (and possibly also their degradation products) act as surfactants to improve the transportation of HVP with the steam and / or condensed water to die production well.

[0040] In the invention, the steam / alkanolamine blend contains less than 25 parts-per-hundred-by- weight (pphw) of ethylene oxide-capped and propylene oxide-capped glycol ether, based on the combined weight of alkanolamines and glycol ethers. As used hereafter, ethylene oxide-capped glycol ethers means that the ethylene oxide cap comprises 1 to 3 ethylene oxide units. As used hereafter, propylene oxidecapped glycol ethers means that the propylene oxide cap comprises 1 to 3 propylene oxide units. Exemplary “capped glycol ethers” conform to Formula 1(a) or 1(b):(la) RO-(CH2CH(CH3)O)m(C2H4O)n H(lb) RO-( C2H4O)O(CH2CH(CH3)O)PH wherein:• R is a lineal', branched, cyclic alkyl, phenyl, or alkyl phenyl group of equal to or greater than 4 carbons,• m is on average 0 to 3,• n is on average 1 to 3,• o is on average 0 to 3, and• p is on average 1 to 3,

[0041] In some embodiments, the steam / alkanolamine blend contains no more than 24 pphw capped glycol ethers, based on the combined weight of alkanolamines and glycol ethers, or no more than 22 pphw or no more than 20 pphw or no more than 18 pphw or no more than 16 pphw or no more than 14 pphw or no more than 12 pphw or no more than 10 pphw or no more than 8 pphw or no more than 6 pphw or no more than 4 pphw or no more than 2 pphw or 0 pphw. There is no minimum amount of glycol ether desired. In some embodiments, the steam / alkanolamine blend contains no glycol ethers, but some embodiments of the steam / alkanolamine blend contain at least 1 pphw glycol ethers, based on the combined weight of alkanolamines and glycol ethers, or at least 5 pphw or at least 10 pphw.

[0042] In some embodiments, the steam / alkanolamine blend contains no more than 50 pphw of fatty alkyl esters, based on the combined weight of alkanolamines and fatty alkyl esters, or no more than 40 pphw or no more than 30 pphw or no more than 25 pphw or no more than 20 pphw or no more than 18 pphw or no more than 15 pphw or no more than 12 pphw or no more than 10 pphw or no more than 8 pphwor no more than 6 pphw or no more than 4 pphw or no more than 2 pphw or 0 pphw. There is no minimum amount of fatty alkyl esters desired. In some embodiments, the steam / alkanolamine blend contains no fatty alkyl esters, but some embodiments the steam / alkanolamine blend contains at least 1 pphw fatty alkyl esters, based on the combined weight of alkanolamines and fatty alkyl esters, or at least 5 pphw or at least 10 pphw. Examples of fatty alkyl esters include methyl, ethyl, n-propyl, isopropyl, or n-butyl esters of C4 to C22 fatty acids, such as fatty acids derived from soya, canola, and other vegetable oils.

[0043] The effectiveness of the steam / alkanolamine blend can be determined by measuring the production difference in a well between ordinary steam and steam that contains the alkanolamine mixture; the difference is sometimes called “oil uplift.” For example, in some cases, the first production in a well is with ordinary steam, and then an additive package is tested in the steam later in production, to judge how effective the additive package is for that particular well. In another example, a production well in which the additive package is used is compared to the production of an analogous well in which only steam is used. In some embodiments, the oil uplift of HVP at the production well using the steam / alkanolamine blend is at least 5 percent greater than production using only steam or at least 30 percent greater or at least 50 percent greater.

[0044] As previously discussed, HVP is often recovered as an emulsion of HVP and water. HVP can be recovered from the emulsion by adding a demulsifier and decanting to separate the aqueous and organic phases. Demulsifiers are known and commercially available. They include polyol block copolymers, alkoxylated alkyl phenol formaldehyde, epoxy resin alkoxylates, amine-initiated polyol block copolymers, modified silicone polyethers, and silicone polyethers. They are available under the DEMTROL™, DOWSIL™, and XIAMETER™ trademarks.

[0045] The following examples show the performance of specific embodiments of the alkanolamine mixture in a laboratory apparatus that simulates performance of the alkanolamine mixture in steam recovery processes in in-situ oil sands extraction.EXAMPLES

[0046] For the Examples, sand cores saturated with dewatered native bitumen are tested in a test apparatus that is illustrated in FIG. 1. The apparatus contains a fluid-tight pressure vessel, which fits inside an oven. The bottom of the pressure vessel can hold liquid, and a raised glass cup stands on tripod legs above the expected level of liquid in the pressure vessel. A post from the top of the pressure vessel suspends the following components over the cup:• a cold finger that is 6 inches long and 0.5 inch in diameter; and• a synthetic sand core that encloses the cold finger and is 6 inches long and 1.5 inches in diameter. Feed lines inside the post connect the cold finger to a cooling water source outside the oven and bring pressurized cooling water to and from the cold finger. The feed lines are insulated to minimize both the heating of the cooling water in the feed lines and the condensation of vapors in the pressure vessel on the feed lines. Cooling water in the feed lines and the cold finger is under pressure of 30 to 35 bar to minimize flashing and cold spots. The test apparatus simulates conditions in an underground reservoir in which a steam / alkanolamine blend (evaporated from the bottom of the pressure vessel) encounters sand that contains bitumen at a lower temperature than the steam (due to the presence of the cold finger).

[0047] Sand cores are made by placing crushed sandstone in a cylindrical mesh (6 inches long by 1.5 inches in diameter, with a 0.5-inch gap in the middle for a cold finger). Each sand core is dipped in dewatered native bitumen at 60°C for 24 to 48 hours to completely saturate the core with bitumen. The saturated core is quenched to room temperature. The bitumen reaches a viscosity of around 1,000,000 cP. Each core is weighed before and after saturation, so that the quantity of bitumen in the saturated core is known.

[0048] The alkanolamines listed in Table 1 are obtained from commercial vendors.

[0049] Aqueous solutions are made that contain 5000 ppmw of the alkanolamines listed in Table 1.In each example, a 0.4 L portion of an aqueous solution is added to the bottom of the pressure vessel. A three-legged collection cup of known tare weight stands above the level of the additive solution. A saturated core is weighed and suspended on the cold finger from the top of the pressure vessel, above the open mouth of the glass collection cup.

[0050] The pressure vessel is sealed, placed in the oven and heated about 60 minutes for the vessel to reach temperatures around 225°C, while cooling water flows through the cold finger. We estimate that the saturated core has a surface temperature of 225°C and an interior temperature of 180°C. The system is maintained in this state for 6 hours while monitoring temperature across the core and the pressure vessel. During this time, an emulsion of bitumen and water drips from the saturated core into the collection cup.

[0051] After six hours, the pressure vessel is removed from the oven and quenched to room temperature to reduce dripping of the bitumen from the core.

[0052] The amount of bitumen that has been recovered (% Recovery) from the saturated core is determined by two methods:• First, the core is recovered and weighed. The difference in weight from the saturated core before and after the test is considered to be the amount of recovered bitumen.• Second, the emulsion collected in the cup is weighed. An aliquot of the emulsion is tested to measure the content of bitumen in emulsion. The total amount of bitumen is calculated as this bitumen content times the amount of emulsion collected.Both numbers are averaged to get the amount of bitumen recovered in the experiment. The results are shown in Table 1. IE1 - IE3 are examples of the invention. CE1 - CE7 are comparative examples.

[0053] Inventive Examples 1E1 to IE 3 show that, at temperatures above 200°C, alkanolamines that meet the vapor-pressure, pKa value, and HLB-Factor limits recover more bitumen than alkanolamines that do not meet the limits.Table 1

Claims

CLAIMSWe claim:

1. A process for in-situ recovery of bitumen or heavy oil, which is collectively called “high viscosity petroleum” or “HVP”, from an underground reservoir that contains HVP, comprising the steps of: a) injecting into the reservoir a steam / alkanolamine blend that comprises: i) steam at a temperature from 200°C to 280°C: and ii) at least 100 parts-per-million-by-weight (ppmw) of one or more alkanolamines, called “select alkanolamines,” that (1) have a vapor pressure (Pv) of at least 0.001 mm Hg at 20°C, and (2) have a pKa value of at least 9.0, and (3) have an HLB-Factor above 0.5; and iii) less than 25 parts-per-hundred-by-weight (pphw) of glycol ether that is capped by ethylene oxide or propylene oxide, called “capped glycol ethers”, based on the combined weights of the alkanolamine mixture and capped glycol ethers, under conditions such that HVP flows to a production well; and b) recovering the HVP from the production well.

2. The process of Claim 1 wherein the select alkanolamines are each individually represented by Formula 1wherein: a) R1is an alkyl group; and b) R2and R3are each individually selected from hydrogen, alkyl moi e ties, alkanol moieties which comprise an alkyl group with a pendant or terminal hydroxyl group, and alkylamine moieties which comprise an alkyl group with a pendant or terminal amine group.

3. The process of Claim 2 wherein the select alkanolamines each individually have a molecular weight from 60 Da to 180 Da.

4. The process of Claim 2 wherein the vapor pressure (Pv) of the select alkanolamines at 20°C is from 0.10 mm Hg to 5 mm5. The process of Claim 2 wherein the pKa value of the select alkanolamines is from 9.1 to 10.5.

6. The process of Claim 2 wherein the HLB-Factor of the select alkanolamines is from 0.56 to 1.1.

7. The process of Claim 2 wherein the normal boiling point (at 1 atm pressure) of the select alkanolamines is from 140°C to 200°C.

8. The process of Claim 2 wherein: a) the vapor pressure (Pv) of the select alkanolamines at 20°C is from 0.10 mm Hg to 5 mm b) the pKa value of the select alkanolamines is from 9.1 to 10.5 ; and c) the HLB-Factor of the select alkanolamines is from 0.56 to 1.1; and d) the normal boiling point (at 1 atm pressure) of the select alkanolamines is from 140°C to 200°C.

9. The process of Claim 1 wherein from 50 weight percent to 100 weight percent select alkanolamines are selected from monoethanolamine, N-methyl ethanolamine and N,N-dimethylethanolamine.

10. The process of any one of Claims 1 through 9 wherein the steam temperature is more than 220°C and no more than 260°C.

11. The process of Claim 10 wherein the steam / alkanolamine blend comprises no more than 10 pphw of capped glycol ethers, based on the combined weights of alkanolamines and capped glycol ethers; and no more than 50 pphw fatty alkyl esters, based on the combined weight of alkanolamines and fatty alkyl esters.

12. The process of Claim 10 which is a SAGD process.

13. The process of Claim 10 wherein select alkanolamines make up at least 50 weight percent of alkanolamines in the steam / alkanolamine blend.

14. The process of Claim 10 wherein the steam / alkanolamine blend comprises at least 500 ppmw of the select alkanolamines.

15. The process of Claim 10 wherein the steam / alkanolamine blend comprises from 1000 ppmw to 5000 ppmw of the select alkanolamines.

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