U.S. patent application number 14/428138 was filed with the patent office on 2019-01-24 for treatment of produced water with seeded evaporator.
The applicant listed for this patent is BL TECHNOLOGIES, INC.. Invention is credited to Jiyang XIA.
Application Number | 20190024492 14/428138 |
Document ID | / |
Family ID | 50263141 |
Filed Date | 2019-01-24 |
United States Patent
Application |
20190024492 |
Kind Code |
A9 |
XIA; Jiyang |
January 24, 2019 |
TREATMENT OF PRODUCED WATER WITH SEEDED EVAPORATOR
Abstract
Produced water, for example from a steam assisted gravity
drainage (SAGD) or cyclic steam stimulation (CSS) heavy oil
recovery operation, is treated to recover water that is re-used to
create steam. The produced water is treated in one or more thermal
treatment devices such as an evaporator and a crystallizer. The
thermal treatment device is seeded, for example with a calcium or
magnesium salt. The thermal treatment device produces a blowdown or
slurry comprising super-saturated solids and organic compounds. A
solvent is added to the blowdown or slurry. The solids precipitate
and are separated from the blowdown or slurry. The solvent may be
recovered for re-use in treating more blowdown or slurry.
Inventors: |
XIA; Jiyang; (Shnaghai,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BL TECHNOLOGIES, INC. |
Minnetonka |
MN |
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20150292314 A1 |
October 15, 2015 |
|
|
Family ID: |
50263141 |
Appl. No.: |
14/428138 |
Filed: |
August 19, 2013 |
PCT Filed: |
August 19, 2013 |
PCT NO: |
PCT/US2013/055544 PCKC 00 |
371 Date: |
March 13, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61700645 |
Sep 13, 2012 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C02F 9/00 20130101; C02F
2101/32 20130101; C02F 1/048 20130101; E21B 43/40 20130101; C02F
1/52 20130101; C02F 1/40 20130101; C02F 1/26 20130101; E21B 43/24
20130101; E21B 43/2408 20130101; C02F 2001/5218 20130101; C02F
2103/10 20130101; C02F 1/72 20130101 |
International
Class: |
E21B 43/40 20060101
E21B043/40; C02F 9/00 20060101 C02F009/00; E21B 43/24 20060101
E21B043/24 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2012 |
CA |
2794356 |
Claims
1. A process for extracting oil, the process comprising the steps
of: a) producing steam; b) injecting the steam into a formation
comprising oil; c) withdrawing a mixture of water and oil from the
formation; d) separating produced water from the mixture of water
and oil; e) treating the produced water including in a seeded
evaporator to produce a distillate and a blowdown; f) using the
distillate to produce additional steam for injection into the
formation; g) mixing a solvent with the blowdown; and, h) after
step g), separating precipitated solids comprising the one or more
salts from the slurry.
2. The process of claim 1, wherein the oil is heavy oil or
bitumen.
3. The process of claim 1, wherein steps a), b), and c) are part of
a steam assisted gravity drainage (SAGD) or cyclic steam
stimulation (CSS) operation.
4. The process of claim 1, wherein step e) comprises treating the
produced water with an evaporator to produce an evaporator blowdown
and treating the evaporator blowdown in a crystallizer to produce
the blowdown.
5. The process of claim 1, wherein the solvent comprises DIPA.
6. The process of claim 1, wherein the precipitated solids comprise
silica.
7. The process of claim 1, further comprising steps of recovering
solvent from the mixture with the blowdown and mixing recovered
solvent with additional blowdown.
8. The process of claim 7, further comprising a step of removing a
remainder of the blowdown from the process after the steps of
recovering solvent and separating precipitated solids.
9. The process of claim 7, further comprising treating organic
compounds in a remainder of the blowdown and returning treated
blowdown to the process at or upstream of step e).
10. A method for treating a mixture having water, one or more salts
in solution and one or more organic compounds, the method
comprising the steps of, a) treating the mixture in an evaporator
to produce a concentrate; b) adding a source of ions to concentrate
in the evaporator; b) mixing concentrate with a solvent; and, c)
removing precipitates of the one or more salts and one or more
organic compounds from the seeded concentrate.
11. The method of claim 10, further comprising a step of recovering
at least some of the solvent from the mixture of concentrate and
solvent.
12. The method of claim 11, further comprising a step of mixing
recovered solvent with additional concentrate.
13. The method of claim 10, wherein the water comprises produced
water.
14. The method of claim 13, wherein the produced water is extracted
from a heavy oil containing formation after injecting steam into
the formation.
15. The method of claim 10, wherein the concentrate comprises
blowdown from one or more thermal treatment devices.
16. The method of claim 15, wherein the thermal treatment devices
comprise an evaporator or an evaporator and a crystallizer.
17. The method of claim 10, further comprising a step of treating
at least some of the seeded concentrate after step d) to oxidize or
remove organic compounds and returning the treated seeded
concentrate to step a).
18. The method of claim 10, wherein the concentrate has a WSO of 3
wt % or more and the WSO is 20% or more of the TS of the
concentrate.
19. An apparatus for treating produced water, the apparatus
comprising: a) a seeded evaporator to treat the produced water and
produce a blowdown stream; b) a solvent mixing vessel, the solvent
mixing vessel in communication with the blowdown stream; c) a
solvent feeding system in communication with the solvent mixing
vessel; and, d) a solid-liquid separation device.
20. The apparatus of claim 19, wherein the solid-liquid separation
device is incorporated with, or downstream of, the solvent mixing
vessel.
21. The apparatus of claim 19, wherein the one or more thermal
treatment devices comprise two or more thermal treatment devices in
series.
22. The apparatus of clam 21, wherein the one or more thermal
treatment devices comprise an evaporator and a crystallizer.
23. The apparatus of claim 19, further comprising a solvent
recovery system downstream of the solvent mixing vessel.
24. The apparatus of claim 23, further comprising a treatment
system configured to oxidize or remove organic compounds downstream
of the solvent recovery system.
25. A process for treating produced water from heavy oil
extraction, the process comprising the steps of: a) de-oiling the
produced water; b) treating the de-oiled produced water in a seeded
evaporator to produce an evaporator blowdown; c) adding a solvent
to the blowdown; and, d) separating solids from the blowdown.
26. The process of claim 25, further comprising, after step d), a
step of recovering solvent from the blowdown.
27. The process of claim 26, further comprising a step of treating
the blowdown to remove or oxidize one or more organic compounds in
the blowdown and returning treated blowdown to, or upstream of,
step b).
Description
FIELD OF THE INVENTION
[0001] This specification relates to a method and apparatus for
treating water, for example produced water.
BACKGROUND
[0002] Canadian Patent 2 509 309 by Heins, entitled Water Treatment
Method for Heavy Oil Production Using Calcium Sulfate Seed Slurry
Evaporation, describes an evaporator based method of treating
produced water from heavy oil production. Produced water is first
treated in a de-oiling step to reduce oil and grease to about 20
parts per million or less. De-oiled water is introduced into an
evaporator to produce a distillate and an evaporator blowdown
containing concentrated residual solids. The distillate is used,
optionally after further polishing, to create steam in a
once-through steam generator or other boiler. The evaporator
blowdown may be further treated in a crystallizer.
SUMMARY
[0003] The following summary is intended to introduce the reader to
the detailed description to follow and not to limit or define the
claimed invention.
[0004] Evaporator blowdown may require treatment to remove silica
and/or other contaminants before it can be disposed or re-used. A
crystallizer, for example, ordinarily treats evaporator blowdown to
recover water and produce dry, or easily dried, crystals made up of
solids precipitated from the blowdown. However, when a crystallizer
is used to treat produced water, particularly produced water from
heavy oil production, the crystallizer may instead produce a
slurry. The slurry contains salts, for example silica salts, at
concentrations above their ordinary limits of solubility in water
and yet the solids are not crystallized and cannot be easily
separated from the slurry. Concentrated organic compounds from the
produced water remaining in the slurry may interfere with crystal
growth and precipitation even for over saturated salts in the
slurry.
[0005] In a method and apparatus described in this specification, a
source of ions, for example magnesium or calcium ions, is added to
the evaporator. A solvent, for example diisopropylamine (DIPA),
isopropylamine (IPA), methanol or alcohol, is added to the
blowdown. The solvent is later recovered from the solvent-blowdown
mixture. Solids are separated from the blowdown before or after the
solvent is recovered. Optionally, the blowdown may be further
concentrated, for example in a crystallizer, before the solvent is
added. Optionally, treated blowdown may be returned to the
evaporator.
[0006] The method and apparatus are useful, for example, in
providing an alternative means of treating produced water, or other
water containing dissolved salts and organic compounds. The method
and apparatus may be incorporated into a method and apparatus for
extracting heavy oil.
BRIEF DESCRIPTION OF THE FIGURE
[0007] FIG. 1 is a schematic process flow diagram of a produced
water treatment system combined with a heavy oil extraction
system.
DETAILED DESCRIPTION
[0008] FIG. 1 shows a water treatment system 10 in combination with
a heavy oil, for example bitumen, recovery system 12. The heavy oil
recovery system 12 has a boiler 14, an injection well 16, a
production well 18 and an oil-water separator 20. The boiler 14 may
be, for example, a once through steam generator (OTSG) or a
packaged boiler. The boiler 14 produces steam 22 which flows to the
injection well 16. Injection well 16 carries the steam 22 into a
geologic formation 24 containing heavy oil, for example bitumen in
the oil sands areas of Alberta, Canada. The steam 22 fluidizes
bitumen in the formation 24 and later condenses. An oil and water
mixture 26 is produced and withdrawn from the production well 18.
The oil and water mixture 26 is sent to the oil-water separator 20.
Product oil 28 is removed from the oil-water separator 20 for
further refining. Produced water 30, which remains after the
product oil 28 is removed from the oil and water mixture 26, flows
to the water treatment system 10 for further treatment. The heavy
oil recovery system 12 may be, for example, a steam assisted
gravity drainage (SAGD) or cyclic steam stimulation (CSS)
system.
[0009] The water treatment system 10 has a de-oiling unit 50, an
evaporator 52, optionally a crystallizer 54, and a blowdown
treatment system 56. The de-oiling unit 50 receives the produced
water 30 and removes additional oil 51, for example emulsified oil,
from the produced water 30 to produce de-oiled water 58. The
de-oiling unit 50 may be, for example, a dissolved gas flotation
unit, a walnut shell filtration unit, a de-oiling polymer mixing
tank, a sorbent unit, a membrane filtration unit or another device.
A suitable evaporator 52 and crystallizer 54 are available from GE
Ionics, Inc.
[0010] De-oiled water 58 is treated further in the evaporator 52.
Optionally, the de-oiled water 58 may pass through intermediate
treatment steps on the way to evaporator 52. However, a warm lime
softener is not required and is not provided in an embodiment.
[0011] Evaporator 52 may be, for example, a mechanical vapour
recompression (MVC or MVR) evaporator. The evaporator 52 may use a
falling film or other internal arrangement. The evaporator 52 may
have associated equipment used, for example, to alter the pH of the
de-oiled water or remove gasses or alkalinity from the de-oiled
water 58. The evaporator 52 removes water vapour from the de-oiled
water 58. The removed water vapour, when condensed, forms
distillate 60 which is returned to the boiler 14 for re-use in the
heavy oil recovery system 12, optionally after further
treatment.
[0012] The evaporator 52 also has a brine recirculation loop 62. A
seeding chemical 63 is added to the evaporator 52, for example by
injection into the brine recirculation loop 62 as shown, the sump
of the evaporator, a feed line to the evaporator or by other means.
The seeding chemical 63 may be, for example, a magnesium oxide or
calcium salt. The seeding chemical may be added in a dry form or in
solution. A suitable magnesium salt is magnesium oxide. A suitable
calcium salt is calcium sulfate (gypsum).
[0013] An evaporator blowdown 64 is withdrawn from the brine
recirculation loop 62 and fed to the blowdown treatment system 56.
Optionally, the blowdown treatment system 56 may be located within
the brine recirculation loop 62. The evaporator blowdown 64, and
the water in the brine circulation loop 62, have a high
concentration of various contaminants that were present in the
de-oiled water 58. In particular, the evaporator blowdown 64 and
water in the brine circulation loop 62 have a high concentration of
silica. The evaporator blowdown 64 is therefore not suitable for
discharge in many locations. The use of a seeding chemical and a
solvent (to be described below) may be particularly useful when the
evaporator blowdown 64 or liquid in the brine recirculation loop 62
has a water soluble organics concentration (WSO) of 3 wt % or more
and the WSO concentration is 20% or more of the total solids (TS)
concentration. TS is measured by heating a sample to 105 degrees C.
to remove water, then dividing the dry sample mass by the original
sample mass. Total dissolved solids (TDS) is is measured by heating
a sample to 550 degrees C. to remove water and organics, then
dividing the dry sample mass by the original sample mass. WSO is
calculated as the difference between TS and TDS.
[0014] In the water treatment system 10, the evaporator blowdown 64
may be treated further in the optional crystallizer 54.
Crystallizer 54 removes additional water vapour from the evaporator
blowdown 64 which, when condensed, forms second distillate 66.
Second distillate 66 may be returned to the boiler 14 for re-use in
the heavy oil recovery system 12, optionally after further
treatment.
[0015] The crystallizer 54 also produces a crystallizer blowdown
68. Crystallizer blowdown 68 has an even higher concentration of
silica and other dissolved solids compared to the evaporator
blowdown 64. Under some conditions, particularly when treating
produced water 30 from a steam or water flood assisted oil recovery
operation, the crystallizer 54 produces a crystallizer blowdown 68
in the form of a slurry having a high solids concentration. Silica
and other dissolved solids are present in the slurry under
super-saturated conditions but do not precipitate and settle from
the slurry. For example, the crystallizer blowdown 68 may have a
total solids (TS) content of 25 wt % or more or 50 wt % or
more.
[0016] The evaporator 52 and crystallizer 54 are types of thermal
treatment devices, alternatively called distillation devices.
Optionally, alternative thermal treatment devices or concentrating
devices, in one or more stages, may be used to create slurry
similar to the crystallizer blowdown 68 or mixtures similar to
evaporator blowdown 64 or water in the brine recirculation loop 62.
Total organic carbon (TOC) in any of these mixtures 62, 64, 68 may
be 2 wt % of more; total dissolved solids (TDS) may be 10 wt % or
more; and, silica may be 1.5 wt % or more. Blowdown treatment
system 56 may be located to receive crystallizer blowdown 68 as
shown, to receive evaporator blowdown 64 without there being a
crystallizer 54, or to be part of brine recirculation loop 62 in
which case evaporator blowdown 64 stream may be omitted, or
retained as a smaller system bleed with or without evaporator
54.
[0017] The blowdown treatment system 56 shown comprises a reaction
vessel 70, a solvent dosing system 72 and a solvent recovery system
74. The crystallizer blowdown 68 (or evaporator blowdown 64 or
recirculating brine 62) and solvent from the solvent dosing system
72 are added to the reaction vessel 70 and mixed together. The
reaction vessel 70 may be, for example, a mixing tank or a conduit
with in-line mixing. The solvent may pass through a heat exchanger
88 to solvent and thereby cool the crystallizer blowdown 68 (or
evaporator blowdown 64 or recirculating brine 62) before it enters
the reaction vessel 70 if required to maintain a temperature in the
reaction vessel 70 below the boiling point of the solvent or to
maintain a temperature at which the solvent and water are miscible.
Precipitated solids 76 form, settle and are removed from the bottom
of the reaction vessel 70, which acts as an integrated solid-liquid
separation unit. Alternatively, the precipitated solids 76 may be
removed by a separate solid-liquid separation unit such as a
centrifuge, filter press, hydrocyclone, filter or clarifier. In a
further alternative, solvent may be recovered from the crystallizer
blowdown 68 (or evaporator blowdown 64 or recirculating brine 62)
before or after the precipitated solids 76 are removed.
[0018] The solvent is added in a mass ratio of at least 1:1, or
about 5:1 or more, solvent to crystallizer blowdown 68 (or
evaporator blowdown 64 or recirculating brine 62).
[0019] The remaining blowdown-solvent mixture 78 is sent to the
solvent recovery system 74. The solvent recovery system 74 may
comprise a heated decanting vessel. In the case of DIPA, heating
the blowdown-solvent mixture 78 to about 74 degrees C. causes the
solvent to separate from the water and form a liquid solvent phase
over the water. The solvent is decanted and drawn off from the top
of the solvent recovery system 74. Alternatively, other solvents
such as IPA, methanol or ethanol can be extracted from the
blowdown-solvent mixture 78 by distillation. Other solvent
extraction means may be appropriate for other solvents. Recovered
solvent 80 is sent to the solvent dosing system 72 for re-use in
the blowdown treatment system 56.
[0020] The precipitated solids 76 may include some organic
compounds. The precipitated solids 76 may be treated to remove the
organic compounds if required to meet discharge or disposal
requirements relating to the precipitated solids. For example, the
precipitated solids 76 may be dried, heated, exposed to UV
radiation, exposed to microorganisms, embodied in cement, or washed
with water, the solvent used in the solvent recovery system 74, or
another solvent.
[0021] A waste brine 82 is also produced. In a case where the
blowdown treatment system 56 is located within the brine
recirculation loop 62, the waste brine 82 flows to the evaporator
52 to complete the brine recirculation loop 62. In other options,
the waste brine 82 may be discharged or recycled to the water
treatment system 10, for example by being sent back to the
evaporator 52. Treatment unit 90 may extract remaining solvent or
remove organic contaminants form the waste brine 82. Optionally,
chemicals may be added to the waste brine 82 to oxidize remaining
organic compounds. Alternatively, or additionally, the organic
compounds may be digested biologically. In a further alternative,
the organic compounds may be recovered for their value as
industrial chemicals. The treated waste brine 82 may be returned to
the water treatment system 10. However, in some cases the waste
brine 82 is removed from the water treatment system 10, optionally
after treating the waste brine 82 if required to meet any standards
required for discharge or disposal. In this way, the waste brine 82
provides a bleed of water soluble organic compounds from the water
treatment system 10 to inhibit the accumulation of any organic
compounds that are not effectively removed by any process in the
water treatment system 10.
[0022] This written description uses examples to disclose the
invention and also to enable any person skilled in the art to
practice the invention. The patentable scope of the invention is
defined by the claims, and may include other examples that occur to
those skilled in the art.
* * * * *