Note: Descriptions are shown in the official language in which they were submitted.
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W O 97/25150 PCT/GB97/00087
- CYCLONIC SEPARATOR AS~F~1R! Y AND METHOD
Field of the Invention
The present invention relates to apparatus and methods for the separalion of
liquids of differing densilies in prod~ction :,lleall,s from underground wells. More
particularly, the invention relates to the downhole hydrocyclonic separation of a oil
well or groundwater cleanup well prorl~ ~ction stream into two streams, a hrst stream
enriched in oil relative to the production stream, and a second stream depleted in oil
10 relative to the production stream, and transportation of the first, oil-enriched, stream to
the surface.
Back~round of the Inve,~t;G.,
Hydrocyclones are cor"pa-;l, centrifugal separators with no moving parts,
which se,.,a,dle liquids in a liquid mixture. Hydrocyclones are widely used in both
onsl,ore and c~rr:,hore oil production in above-ground applicaliolls such as bulk water
knockout from produced fluids, de-oiling produced water prior to either water
, ~i"; ~tion into a formation or water disposal to a disposal site. In these applications a
plurality of hydrocyclones are typically mounted within a pressure vessel assembly.
Such an asser, Ibly resembles a shell-and-tube heat exc;l ,an~er, in that the
hydrocyclones are mounted to tube sheets which are sandwiched between flanges in
the pressure vessel. The complete pressure vessel assembly typically has a single
inlet for the produced liquid stream, which com,ulises as for example, a mixture of oil
and water and a plurality of outlets for the separ~led liquid streams. The assembly
has an outlet for the "clean water" stream, which is relatively depleted in oil as
compared to the production liquids, and an outlet for the "dry oil" stream, which is
relatively enriched in oil as compared to the produced liquids.
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- Hydrocyclones, as they are employed in oil production and enviro"",e"Lal
cleanup ap~ lions are designed fo,~i"osl to remove oil from water, that is, to
produce a clean water stream with as low a conce"l,~lion of oil as pr~ctic; hle. The
dry oil stream will typically col,lai" about 50 per cent water, by volume, and may
5 ccI ,lai. I more than 50 per cent water. Hydrocyclones, in a si"g:e stage configuration,
- cannot produce both a completely water-free oil stream and a compietely oil-free
water stream; the design pe,ru~ a~ce must be biased towards either the "dry oil"
stream or the "clean water" stream. A clean water stream is obtained at the expense
of "wet oil". Conversely, a dry oil stream is obtained at the expense of oily water.
10-- Hydrocyclone designs that arè exemplary of those in the art are described in British
Patent Application GB-A-2248198, which is incorporated herein by rerer~nce for all
purposes, and U.S. Pat. No. 4,237,006, which is i.,co,,uor~led herein by ,~rerence for
all purposes. Multi-stage sepa, dlor assemblies including multiple hydrocyclones
a"d"ged in series, such as taught by U.S. Patent No. 4,738,779, i"co,~uor~led herein
15 by rararel,ce for all purposes, can achieve improved separation at the expense of
increasing the pressure drop of the liquids moving through the multi-stage assembly.
Hydrocyclones are also useful for making a preliminary separation of oil from
water in the production liquids produced downhole in an oil well prior to the production
liquids being ll~llspo,lad to the surface. This is of particular value in high water cut
2 0 wells, with a high water conlenl, where the production liquids may col ",u, ise about 70
per cent, or more, water. Conve"lionally, this water must be l~nspolled above
ground, at siyl ,iricanl cost and then disposed of, at additional expense. Hydrocyclone
assemblies designed for above-ground use however, are not suitable for downhole
applications where the assembly must be disposed within the bore hole of an oil well.
25 This is bec;~use convenlional hydrocyclone assemblies of sufficient capacity exceed
SUBSTITUTE SHEET (RULE 26)
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- the size limitations imposed by the did",eter of the well. Further, previous dllem,c,ls to
overcome these problems have resulted in addilional complications.
For example, PCT Inle" ,dlional Application WO 94113930 discloses a
downhole separalion appa,~lus in which one or more hydrocyclones are contained
5 within an axially elongate tubular housing, with the inlet of each hydrocyclone
exLend,"g through the wall of the housing and having an opening extemal of the
housing. The se,~,araled dry oil and clean water streams from each hydrocyclone are
lldllspo,led from the housing by a relatively complex system of pipes. With this
appa,dlus there must be sufFcient clearance between the housing and the a~jacenl
10 wall of the well casing to provide a flow annulus for transporting the production fluid to
the hydrocyclone inlets. This limits the diameter of the hydrocyclone housing for a
given size casing, and hence reduces the capacity of the separation apparatus.
Further, the intemal space within the housing, but outside of the separators and
piping, is dry, so that there is a very suLIslar,lial pressure dirrer~r,lial across the walls
5 both of the housing and the piping within the housing. Further, the housing must be
tightly sealed against the full well bore pressure. This obviously requires the use of
heavy gauge and/or speci~'ty materials for construction of the housing, which results
in increased costs for both ",dlerials and fabrication, and increases the risk of failure
of the assembly.
In applications where the pressure of the liquids in the well bore is too low,
pumps and ~csoc~-~ed pump driving equipment, are required. WO 94113930 for
example, discloses placing a pump on the clean water stream to assist in reinjection
of the clean water into the formation. This does not address the important problem of
transporting the dry oil stream to the surface however. U.S. Pat. No. 5,296,153
25 f~iscloses pumping the dry oil stream to the surface and the clean water stream to
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- a,,ull ,er forrnation. Ihis further increases the cost and complexity of oil production
exace,bates the pr~,ble", of loc~li"y the equ;~melll within the well bore and requires
pumping the clean water stream which i"creases both the capital and operating costs
of oil recovery.
The ~ sel ,1 invention overcomes the deric;er,- es of the prior art.
SL.~ of t~e II~C.~
According to the prt:senL invention there is provided a downhole sep~ralion
asser"bly cc ""~,ising an axially elollgale tubular housing defining an i"le",al
chamber and having at least one inlet which is a" ~ns~ed to allow production fluid to
10 flood the chamber. At least one hydrocyclone separator is conlai"ed in the chamber
and has an inlet open to the chamber so that the production fluid in the chamber
enters each sepa,alor. An overflow outlet and an underflow outlet are provided for
each separator and are co",lec~ed to pipes which lead out of the chamber.
By flooding the chamber containing the separator(s) in this way it is
15 unnecess~ry to provide a flow annulus between the housing and the well casing to
supply production fluids to the sepa, ~lor inlet(s) so that the radial clearance between
the walls of the housing and the well casing can be reduced to only that which is
necess~ y to run the housing into the casing. To further reduce costs and further
i"~t:ase c~l-~cily the well casing may be used as the housing in which case the
2 0 clla" ,ber is defined by the well casing and a pair of axially spaced packers which are
well known in the art. The present invention thus allows the diameter of the tubular
housing to be increased to nearly the dia",eler of the casing thereby maximizing the
ca,.acily of the separation apparatus. Further as there is a substantially reduced
and possibly no pressure dirrert:l,lial across the housing wall it is unnecessary to
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W O 97/25150 PCT/GB97/00087~ provide the heavy gauge or specialty Illalelials of the prior art to a~ cvc the same
structural inLey~ ily of the housing, and heavy duty seals are no longer required.
If the pressure in the well bore is low enough that the pumping of the
produotion fluid is required prior to separdlion the sepa(aLio" ap~Ja.dLus p,~r~.dbly
5 includes a pumping unit which pumps prod~ ~ction liquids into the chamber. A second
pumping unit may also be provided if necess~- y, to Ll ans,uG, L the dry oil stream to the
surface. If on the other hand the pressure in the well bore is surric;e~,LI~ high that no
ulJsL,ea-" pumping is required the housing can be provided with a plurality of
apertures so that the production fluid enters the housing at a plurality of locdLio"s
10 along the length of the tubular housing. In this case the size of the apertures may be
smaller than the size of any of the p~Csa9es within the housing and separaLo, (s) to
avoid a flow blockage of the se,. a~ dLor(s) by any solid matter in the production fluid.
r~ ~r~ dbly a plurality of axially sp~csd sepa, ~Lol . are disposed in the
chamber. In order to provide i"crease-l c~,aciLy it may be desirable in some cases
15 for a~acenL sepa, dLor~-. to face in opposite directions with some axial overlap
between polLio"s of adjacenL sepa,aLc" .. Where ~-5 -ce"L hydrocyclone sepdralo, .
do not face in op~,osile dire- Liuns substantial axial overlap may also be provided to
rl l~il l li~e the cc m,ùacLl ,ess and hence the ca~Jacily of the separalor asse" Ibly.
In order to reduce the complexity of the piping and seals required it is
20 desirable for the pipes leading from the overflow outlets of the separators to be
co"ne~Led to a co, 1 ll l ,o" overflow outlet " ,a"irold within the cha" ,L,er and for the pipes
which lead from the u "de, nOw outlets of the sepa, dLul -. to be co""ecLed to a cor, Il l lon
IJI ,de, l1U~IV outlet manifold within the chamber.
For most appli~liol ,s the overflow stream will leave the chamber at one end
2 5 of the housing for Ll dl lspcll Ldlion of a dry oil stream to the surface while the Ul ,de~ no\N
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- stream will leave the c; hdl I~L er at the c: I.posile end of the housing for Ll ~1 ,s~.o, laLio" of
a clean water stream for ~ 1;5pos~l downhole or elsewhere. If all of the overflow outlet
pipes dis.;llar~a through one end of the housing and/or all of the underflow outlet
pipes cliscl,dlya through the opposile end it will be ,lec~ss~ry for a pipe or Illanir
5 lea~ y from the overflow outlet of a sepal~lor to extend past the separ;~lor or
se,l~aralol:i posilioned above it in the c;hdll,ber and/or for a pipe or n)al lir~ld leading
from the ~ elnow outlet of a se~ar;3lor to extend past the se,uardlor or sepa,dlor~
posilio"ad below it in the cilalllber. In this case, the space available for a pipe
adjace"l to the head of each hydrocyclone sepa,dLor may be limited hec~use the
10 head by its nature is the widest part of a hydrocyclone se~aralor. At such locations
the pipe may be formed with a non-circular cross section having s~ ulially the
same cross-se~lional area as do the adjace, ll pc" liul ,s of the pipe. For example, the
non-circular cross section may be sL L,sla"lially kidney-sl ,aped.
of the more il "uo, lanl features of the invention have been
15 SIJIIIIIIal i,ed broadly in order that the detailed desc;l iulion thereof that follows may be
better L~"derslood and in order that the ccnl,iL,utions to the art may be better
a,v,vr~ci '.r~ There are, of course, ~ tional features of the invention that will be
described her~il ,aller and which will form the subject of the appended claims. These
and various other ch~ ~ri:,lics and ad\,~lllayas of the ~resenl invention will be
2 Q readily a,~par~nl to those skilled in the art upon reading the following detailed
des~i~,liG" of the ~r~r~"ad en,l,odi",e"ls of the invention and by rere"il~g to the
accol I ,,.,anying drawings.
Other objects and advd"lages of the invention will appear from the following
das~ i~lion.
2 5 BRIEF DESCRIPTION OF THE DRAWINGS
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- For a detailed desc;,i, lion of a prere,red embodiment of the invention
, ere~e"ce will now be made to the accc ~ ~ ~pa~ ",~ing drawings wherein:
Figure 1A is a scher"dLic which depicts a down hole hydrocyclone separator
asse",bly in accordance with the present invention shown in a simplified axial cross-
~ 5 se~io" as having a single hydrocyclone;
Figure 1B is a schematic illu~lldliol~ of the e~lbodi~ent of the inventiond epi.~ed in Figure 1A in radial cross-section taken through sec~iGn 1 B-1 B;
Figure 2A depicts a schematic rep,~:se"lalion of an embodiment of the present
invention which includes a first pump for the produced liquids stream and a second
10 pump for the dry oil stream and illustrates an exemplary arrangement of the a~paralus
within a well bore;
Figure 2B depicts in axial cross-section a schematic representation of a first
sub in acco, ddl ,ce with the embodiment of the invention illustrated in Figure 2A;
Figure 2C depicts in axial cross-section a schematic representation of a
15 second sub in accorda"ce with the embodiment of the invention illustrated in Figure
2A;
Figure 2D depicts in axial cross-section a schematic representation of a third
sub in acco~dd"ce with the embodiment of the invention illustrated in Figure 2A;
Figures 3A and 3B are each broken axial section views of portions of a down
hole hydrocyclone separator assei"bly in accordal ,ce with the present invention and
illustrate an asse" Ibly with two hydrocyclones and associated piping and connections;
Figure 4A 4B and 4C are each broken axial section views of portions of a
down hole hydrocyclone separator assembly in accorda,-ce with the present invention
and illustrate an assembly with five hydrocyclones and associated piping and
2 5 connections;
~ SUBSTITUTE SHEET (RULE 26)
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W O 97/25150 PCT/GB97/00087Figure 4D is a radial cross-sectiu" view of the embodiment illustrated in Figure
4A taken through section A-A; and
Figure 4E is a radial cross-section view of the er, Ibodi",ent illustrated in Figure
4B taken through section B-B.
DF~ ~ ~N OF THE I I~Li LI~RED EMBODIMENTS
For purposes of illu~;llalion and not by way of li,,,ilaliû, " the present invention
is des~iL,ed with respect to several exer"~ Idly down hole hydrocyclone separalùr
assen ,blies for separali"g the produced liquids from a well into a dry oil stream and a
10 clean water stream with sdli:,ra~ory capacily compactness and cost for application
to conve, lliGnal high cut oil wells in oil prod~ ~ction or environmental cleanup
Referring now to Figures 1A and 1B there is shown a simplified schematic
d;dyldlll of a first prarar,ed er"bodi-,~ent of the hydrocyclone se,uar~lor assembly of
the prese"l invention comprising a single hydrocyclone. The se~.a,dlor asse",bly
15 denoted g~llardlly by r~rt:~l,ce numeral 13 prer~:rdbly co",,.rises a housing 10 a
hydrocyclone 2 and an internal chamber 20 defined by the inside diameter of housing
10. Optionally upper and lower support plates 3 and 4 respectively may be
provided for su~ û, lil ,9 the piping and hydrocyclone 2 within chamber 20. if support
plates 3 and 4 are used production o~,e"i"ys 11 are provided in support plates 3 and
20 4 so that i"Le",al cl,a",L:er 20 rer,,c.i,~s open to the production liquids. An overflow
manifold 7 and an under~ow manifold 8 extend through chamber 20 and are
pr~:ra,al,ly provided when multiple sepa,dlor assemL)lies are disposed in the well.
Manifolds 7 and 8 are both firmly affixed to both support plates 3 and 4.
Hydrocyclone 2 is prererably of a well known de-oiling configuration such as
25 that described in British Patent Application GB-A-2248198 and has one or more
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tange. ,lial inlets 9 which are open.to the interior of the housing 10. An underflow pipe
6 is hydraulically co, Ille~;led to the u"de,no~lv outlet 19 of the hydrocyclone separaLor
2, and is hydraulically co"r,e.~d to the underflow ",a"irold 8. Similarly an overflow
outlet pipe 5 is con, lec~ed to the overflow outlet 15 of hydrocyclone separator 2 and
5 is co"ne~ed to the overflow ma"ir.'d 7. In ope,dlion one or more separator
assemblies 13 are run into the cased well bore with minimal clearance between the
exterior wall of housing 10 and the interior wall of the well casing. Production fluid
which has either been pressurized by a pump or is naturally under pressure floods
the intemal chamber 20, and enters hydrocyclone separator 2 through se,uar~lor
10 inlet(s) 9. If support plates 3 and 4 are provided production fluid floods chamber 20
by flowing through production openings 11. The production fluid is caused to swirl
within hydrocyclone 2 by the tangential orientation of inlet(s) 9. In hydrocyclone
se~a, alor 2 the production fluid is separated into a clean water stream which flows to
the underflow and a dry oil stream which flows to the overflow as is well known in the
15 art. As noted above, the clean water stream is enriched in water relative to the
pro-illction liquid stream while the dry oil stream is enriched in oil relative to the
prodl Iction stream. The underflow from the hydrocyclone separator 2 flows through
the u"de,llo~v outlet pipe 6 to underflow manifold 8 and is preferably transported
downhole below asse",bly 13 for ~i$pos~l or reinjection into the formation. The dry oil
20 from the overflow outlet 15 flows up through the overflow outlet pipe 5 to overflow
Illdllir~ld 7 and then to the surface where it may be further treated. In applications
where a single hydrocyclone asser"bly is .~ ,osed within the oil well underflow pipe
6 is ,."-ererably connected to a ~lispos~l pipe (not shown) below housing 10 whereby
ar,irol ls 7 and 8 are no longer necess~ry.
SUBSTITUTE SHEET (RULE 26
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Rer~llill3 now to Figure 2A there is shown a schematic representation of a
second ~ rer-~d er"L,o.li",ent of the se,~,a,dlor asse"lbly of the ,crt:se"L invention
including a pluraiity of the sepa~dLor assemblies 13 shown in Figure 1A. Se,cJdrdLor
assembiies 13 are dis,uosed between two axially spaced packers a lower packer 93
5 and an upper packer 95. Upper packer 95 is o~lio. ,al. Upper packer 95 is used when
an upper rcimdlion is isolaLed from the roi",aLion having pe,ru,aLiol,s 90; when the
di;,posal liquid such as water is to be disposed above the sep~r~Lor assembly; or
when it is desirable to prevent the prod~ ~ction fluids from pe, rurdLiolls 90 from flowing
up hole. Two such sepdldLor assemblies top sepa,dLor assembly 13A and bottom
10 sepaiaLor 13B are shown although any number of separator assemblies 13 may be
used without de,ual Lil ,9 from the scope of the present invention. It should be
appreciated that sepa,dLor asse,nblies 13A and 13B are substantially the same as
sepdl dLor asse" ILIy 13 described with respect to Figure 1 A and like reference
nul,lei~ls will be used for like parts with the designation A or B for upper and lower
15 assemblies 13Aand 13B respectively.
A prodl ~ction pump 31 is provided for pumping the production fluids and an
overflow pump 32 is provided for pumping the overflow (dry oil) stream to the surface.
Pumps 31 and 32 are driven by drive means such as one or more drive motors 30.
For illustration and not by way of limitation pumps 31 and 32 may be electric
20 sul-,lle,~iL,le pumps pluy~ssive cavity pumps or beam (or rod) pumps all of which
are well known in the art. Many other types and coml;,il IdliOl)s of pumps and drive
systems may be successrully used in accorda"ce with the present invention such as
jet pumps and gas lift systems. As will be readily apparent to one skilled in the art a
range of artificial lift systems may be used in conjunction with the natural reservoir
2 5 pressure without de~al li"g from the scope of the present invention.
--10--
SU~ 1 l l ~JTE SHEET (RULE 26)
~ .
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W O 97/25150 PCT/GB97/00087Pumps 31 32 and drive motor 30 are ,c,erer~bly ~l;sl~oserl above separator
asse,),biies 13A 13B to simplify connection to a power source (not shown) which
supplies electric or hydraulic power to drive motor 30. Other a" ~"ye"~e, ll:j of pumps
31 32 and drive motor 30 with respect to se,c,ardlor asser~ Iblies 1 3A and 1 3B are of
5 course, possible without depal li- ,y from the scope of the invention.
While the embodiment of the invention described with respect to Figure 2A
illustrates only two sepa, alor asser, 'L,lies 1 3A and 1 3B any number of such
assel"blies may be used in conjunction with the apparatus described immediately
below. Sepa,dlor asser"l.lies 13 are thus modular and the number of such modules
10 used should be dete""ined in pr~ice by the desired overall capacity available
reservoir pressure and choice and design of pumps.
Referring now to Figure 2B a first or top sub 41 is ~,r~rerably disposed
between drive motor 30 and the sepa~ ~Lor assembly 1 3A as shown in Figure 2A and
hydraulically seals around its pe, i~l ,ery to well casing 17. Sub 41 pl ~r~rdbly includes
5 a p~-ss~ge 111 for the production fluids being pumped an overflow p~.ssage 71 and
a blind bore 81 for receiving one end of underflow manifold 8A to prevent upward
p~ssage of the u"de, n-~ stream. P~-ss~ge 111 allows the production fluids from the
outlet of production pump 31 to flow to separator assembly 13A. Overflow p~.ss~ge
71 in sub 41 i"ler~;onr,e.;ls the overflow manifold 7A (shown in Figure 1A) of separator
20 assen,bly 13A to a dry oil conduit means (not shown) extending to the surface through
which the dry oil is l,d"spolled to overflow pump 32. Blind bore 81 of sub 41
hydraulically seals off one end of underflow manifold 8A.
- R~:re"i"~ now to Figure 2C a second or connecting sub 42 ,~"ere~dbly is
disposed between any two of separalor assemblies 13 such as se,oaralor asse" ~blies
25 13A and 13B as shown in Figure 2A for connecting ~ cent assemblies. Sub 42
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ert:rdbly includes a-p:l-ss~ge 211 for the pumped prod~tion fluids an overflow
~,~ss~ge 72 and an underflow p: ~ss~ge 82. r~cS~9e 211 hydraulically il llel ~"nects
the two separator assemblies 13A and 13B adjacent to sub 42 for the flow of
production fluids. Thus the production fluids may pass freely between i"Le" ,al
5 ~ Idl "ber:,20A and 20B of sepa, ~Lor asserl Iblies 13A and 13B. Overflow r~-ss~ge 72
hydraulically i"ler~n"ecls the overflow ",~,.ir~ 7A and 7B of any two separ~lol
asser,~blies 13 adjacent to sub 42 such as top separator assembly 13A and bottom
sepa~dlor assembly 13B. Similarly underflow p~ss~ye 82 hydraulically i"ler~,1"ecl:,
the underflow manifolds 8A and 8B of the two sepa,alor assemblies 13 adjacent to
10 sub 42.
Rt:r~llilly now to Figure 2D a third or bottom sub 43 ,u,ere,~bly is disposed
between the bottom separalor assen,l.ly 13B and lower packer 93. Sub 43 ,urer~rably
includes underflow p~ss~ e 83 which Le""i"ales at its lowest end in a threaded pipe
box 80. Underflow pAcs~9e 83 hydraulically co""e.;ls the underflow manifold 8B of
15 the bottom se~,ardlor asser"bly 13B to a disposal pipe 84, shown in Figure 2A.
Referring again to Figure 2A in operation production fluids enter the annulus
85 fommed between housing 10 and well casing 17 through production perforations 90
in casing 17. The prod~ ~tion fluids are drawn into production pump 31 and pumped
through production p~ssz3-Je 111 of first sub 41 to top separator asse",bly 13A.
2 0 Should optional support plates 3A and 4A be used the production fluids flood
cl,~",ber 20A by passing through production openings 11A. (See Figure 1A). The
production fluids also pass through production p~Cs~9e 211 in second sub 42 and as
above flood the intemal chamber 20B of bottom separator assembly 13B below sub
42. In this way the intemal chamber 20 of each of the separator assen,blies 13 is
25 flooded with production fluids.
--12--
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As described--above with l~rer~nce to Figure 1A the pro~uction fluids are
separdled by the hydrocyclones 2A and 2B with the overflow streams passing into
overflow ,,,a,,irulds 7A and 7B and the underFlow streams passing into underflow
~a~,iruids 8A and 8B. The overflow Illallir~lds 8A and 8B of the several se~.a,dlor
assei "blies 1 3A and 1 3B form a continuous manifold by virtue of pA~s~e 72 through
sub 42. The overflow thus flows up through over~low manifolds 7A and 7B through
overflow p:~ssage 72 of sub 42 through overflow pA-ss~ge 71 of sub 41 to overflow
pump 32 which then pumps the overflow through recovery pipe 74 extending to the
surface. In wells with sufficient natural reservoir pressure overflow pump 32 is not
1 o required.
Similarly the underflow manifolds 7A and 7B of the several se~ a~lor
asse",blies 1 3A and 13B form a continuous manifold by virtue of passage 82 through
sub 42. The underflow is prevented by blind bore 81 in sub 41 from passing up the
well. The ~",de,llu~lv from all the separator asse,llblies 13 therefore finally exits via
I,~ssage 83 in sub 43 and ~15pos:~1 pipe 84 and may then be i,~ into the
formation via i,.,e_tion perforations 96 loc~ted in the well casing 17 anywhere below
lower packer 93. It should be u"der~ilood that although the embodiment of the
invention described with rerel~l,ce to Figure 2A includes two separator assemblies
13A and 13B any number of modular sep~l~lor assemblies 13 may be used without
departing from the scope of the present invention.
Referring now to Figures 3A and 3B there is shown a third preferred
embodiment of the hydrocyclone separalor assembly of the present invention
generally denoted by, ~rert:"ce numeral 113 which includes two hydrocyclones. The
separdlor assen,bly 113 comprises a housing 100 dt:rillillg an intemal chamber 120
which is sealed at an upper end by a first sealing block 102 and at a lower end by a
-13-
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seco"d sealing block 103. The se,~,aralor assembly may be reversible, in which case
first sealing block 102 seals the lower end and second sealing block 103 seals the
upper end. A production fluid inlet may be provided to separator assemL;ly 113 in
either of two ways. First, if a production fluid pump is provided above the first sealing
5 block 102 (such as prod~ction pump 31 shown in Figure 2A) or below the second
sealing block 103, an inlet 161A into the chamber 120, such as is shown in first
-~ealing block 102, is prerer;3Lly provided through the appr~,uriate sealing block. On
the other hand, if no pump is required, the housing 100 is prt:reraL,ly provided with a
plurality of apertures, such as holes 161B, or slots (not shown) which allow direct
10~ access for the production fluid into the chamber 120. As will be apparent to one
skilled in the art, altemative types of apertures may be provided without departing
from the scope of the p, t:senl invention.
An upper hydrocyclone separator 104 and a lower hydrocyclone se~u~lalor
105, pr~rel ~bly are a" dnged in parallel within housing 100. The hydrocyclone
sepa,dlor:j 104 and 105 have a de-oiling configuration which is well known in the art.
Both separ~lo,~ 104 and 105 have one or more tangential inlets 106 which are open
to the interior of separators 104 and 105. Although the inlets are illustrated as being
in the plane of the section, this is only for clarity and, in ,~.,actice, the inlets will
generally be out of this plane.
An underFlow pipe 107 is connected to the underflow outlet 115 of the upper
hydrocyclone separalor 104 and leads down the chamber 120 past the lower
separaLor 105. In the region a~jacenl to the head 117 of the lower separator 105, the
first underflow outlet pipe is provided with a non-circular portion 107A which, in plan,
may have a su~s~a"lially kidney-shaped cross sec~io, I. This cross-sectional
25 configuration ensures that the cross-sectional area of the pipe underFlow pipe 107
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remains sl~hst~ntially ulldldllyad as the non-circular portion 107A of underflow pipe
107 p~-sses the head of lower sepd,alor 105 despite the limited space available
a.5ace, ll to the head 117 of the seco, Id sepa, dlor 105. Of course where not required
by space lilllildlions~ non-circular portion 107A is not necess~ry so long as the cross-
5 se~lio,lal area of underFlow pipe 107 is maintained s~ sl~-,Lially cGnsldnl. It should
also be au~ c led that non-circular portion 107A may include a plurality of pipes
exLencling between outlet 115 and the main tubular portion 107B of pipe 107 it being
illl,l~olldlll that the cross-sectional flow area is s~hst~rltially the same around head
117 as with portion 107~ However multiple pipes are not prere"~d be~l-se they
l o take up more area within housing 100 than non-circular portion 107A. The underflow
outlet pipe 107 leads to a manifold 108 which is shown as a part of the second
sealing block 103. The u"de,llu~lv outlet 119 of the lower sepdralor 105 is also
co""ec~:d to manifold 108 so that the underFlow streams from the two separators 104
105 are co, l ,~i"ecl prior to passing through second sealing block 103.
Similarly an overFlow outlet pipe 109 leads from the outlet 121 of lower
separalor 105 past the upper sepd(dlor 104 and the overFlow stream from lower
se~,d,dlor 105 co",L,;"es with the overflow stream from outlet 110 of the upper
sepa,dlor 104 in a "~a,lirùld (not shown) similar to manifold 108 which then passes
through first sealing block 102.
It should be ap~ recidled that it is most desirable to Ill~cillli e the size of the
head 117 of the separdlur~ within housing 100 or casing 17 if no separate housing is
utilized for the sepd,dlor assembly to maximize the separation capacity of each
sepdl dlor. However the remaining cross-sectional area around head 117 must
accor~ odale not only underFlow manifold 107 and overflow Ilrdllirold 108 but must
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also leave adequate flow area for-the production fluids flowing by head 117 to feed
other se~ua, dlul ~ in the asse" Ibly.
The construction of the Se~Jdl dlor asse" Ibly 1 13 (as well as separalor
asse"lL,ly 13, Figure 1A) is pr~r~:r~Lly si"",liried by the use of many standard pipe
se~,Lions as are well-known in the art, and hydrocyclones of de-oiling configurations,
also well known in the art. Generally, the only specially parts required are the first
sealing block 102 and the second sealing block 103, the non-circular pipe section
107A (if ,~ecess~fy), and an adapter 213 provided between the two se~a,~lor:i 104,
105 for connecting separator outlets 107, 121 to correspo~ Idi, ,y pipes.
In operation, running the separator assembly 113 into a well bore prerer~bly
requires only minimal clearance between the walls of housing 100 and the well
casing, i.e., only enough clearance to run the assembly through the well casing. For
example, the dian,~l, ical cleardnce may be as small as one sixteenth of an inch. No
cleara"ce is required for the flow of prod~ction fluids, as in the prior art, since
chamber 20 is open to the flow of production fluids. Production fluids flood the
intemal cll~l"ber 120 through the allerllali~/e production fluid inlets described above.
The production fluids in the intemal chamber 120, which have been either pressurized
by a pump or is naturally under pressure, enters the two separalo, :,104,105 through
respective separaLor tangential inlets 106, and is c;l~sed to swirl by the La"genLial
orientation of inlets 106. In the separ~Lul ~ 104, 105 the production fluids are
separ~led into a clean water stream which flows to the underflow and a dry oil stream
-which flows to the overflow. As noted above, the clean water stream is enriched in
water relative to the production fluids, while the dry oil stream is enriched in oil relative
to the production fluids. In the el"bodi",elll illustrated in Figures 3A and 3B, the
underflow from the two se~,a,dlor~ flows through the second sealing block 103, and
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may then be lldnspo,~Led downho~e for ~iispos~l or rei";e_tion via outlet 184. The dry
oil stream from the overflow flows up through the first sealing block 102 and then to
the surface where it may be further treated.
Although the embodiment described above has only two hydrocyclone
5 sepa,dlo,s further sepa,dlor~ can be used if required. In this case a co"""o"
underFlow outlet pipe is plt:rerdLIly progressively larger in cross-sectional area as it
extends down the chamber 120 bec~se the underflow outlet streams from further
se~aralu, ~i join the common u "de, llow outlet pipe sl ~1 ,sl~ulially increasing the volume
of flow. Similarly a con ", IGn overflow outlet pipe is pr~:rerably proy~ essively larger in
10 cross-sectional area as it extends up the chamber because the overflow outlet
streams from further separators join the common overflow outlet pipe also increasing
the volume of flow.
With respect to the embodiment of the separator assembly described above
with r erer~"ce to Figures 3A and 3B the outside diameter of housing 100 is
15 p,-ere,dbly less than the inside diameter of the well casing by only the clearance
necessa,y to run the assen,bly 113 into the well. For example the diametrical
cieardnce may be a~ ru~i",~lely one-sixteenth of an inch. This maximizes the
dia",~:ler of the separator assenlbly and housing and ll,~,ci,l,i~es the size of
separators 104 and 105 thereby maxi"~i~i"g the capacity of the entire separator
2 o assemLIly.
For example assen,blies such as assen,bly 113 having two hydrocyclones in
accorda"ce with the embodiment desc, ibed above have been constructed and tested
where the outside diameter of housing 100 is 4.5 inches and the length of housing
100 is about 13 feet. Such an assen,bly is suitable for use in 5 inch well casing
25 having an inside diameter of 4-9/16 inches. A capacity of up to 4000 barrels of
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production fluid per day may be achieved with such a two hydrocyclone assembly.
The cross-sectionai area of the head of each hydrocyclone 104 and 105 may be one-
half or ylt~aler than the cross-sec~ional area of the housing 100. It is ,ùr~rer~ble to
l"~i",i~e this ratio to ",~ci",i~e the capac;ily of the separdlor assembly. The
5 r~" ,ai, lil Iy cross-seclional area of housing 100 is used for manifolds 107 108 and the
flow of production fluids.
Referring now to Figures 4A - 4E there is shown a fourth ~rere" t:d
e~"bodi",ent of the hydrocyclone separator assembly of the present invention which
includes five hydrocyclones and is denoted generally by reference numeral 313. The
10 se~Jaralor asse~ ~ Ibly 313 cor",u, ises a tubular housing 300 deril ,i"g an internal
chamber 320 which is sealed at an upper end by a top adapter 310 and at a lower
end by a bottom add~ler 380. Top adapLer 310 and bottom adapter 380 are secured
to housing 300 by threaded collars 311 and 321 respectively. Sepa,~lor assembly
313 may alle",dli~/ely be reversed so that addpler 310 is disposed at the lower end
15 and ada~lor 380 is dis~,osed at the upper end.
A production fluid inlet may be provided in either of two ways. First if a
prorluction fluid pump is provided above the top ada~.ter 310 (such as production
pump 31 shown in Figure 2A) or below the bottom adapler 380 an inlet 361A into the
chamber 320 is provided through the ap~ ,upriate adapter such as shown in adapter
20 310. On the other hand if no pump is required the housing 300 may be provided
with a plurality of apertures such as holes 361B or slots (not shown) or screened
openings (not shown) which allow direct access of the production fluids into the
chamber 320. As one skilled in the art will immediately understand other means of
providing the plurality of apertures may be employed without departing from the scope
2 5 of the invention.
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The five hy~rocyclone separ~ , de"oled in order moving from the top
adapler 310 to the bottom adapter 380 by r~rer~nce numerals 301, 302, 303, 304,
and 305, are pl-er~,dL)ly arranged in parallel within housing 300. Once again, the
hydrocyclone separators have a well known de-oiling configuration as is well known in
5 the art. Each of the se,~ ardlu,~ has one or more lange"lial inlets (not shown, but
su6sl~r,lially similar to inlets 106 das~ibed above with rerar~nce to Figures 3A and
3B) which are open to the interior of the separalor:i.
An ~" ,del nu~,v pipe 360 conl le~;ls each of the underflow outlets of the
hydrocyclone separdlor~ 302, 303, and 304, to an underflow manifold 340. For
10 example, an u".lel nO~lv pipe 360A co""e-;ls the underflow outlet of the top
hydrocyclone 301 to underflow manifold 340. Underflow pipe 360A may vary slightly
in its cross-sectional configuration from underflow pipes 360 because underflow pipe
360A forms the top inlet of underflow manifold 340. U"del no~N manifold 340 extends
down through the chamber 320 and past the lowest hydrocyclone 305, into bottom
~dal ~ler 380. The underflow from hydrocyclone 305 also leads to bottom adapter 380,
so that the underflow stream from all of the hydrocyclone separators 301 - 305 is
combined prior to passing through bottom adapter 380. The underflow from
hydrocyclone 305 communicates with the bore 381 of bottom adapler 380, as does
underflow ~ ~ ~anirùld 340.
Rere,,iny now to Figures 4A, 4B, 4C and 4E, in the region adjacent to the
heads 117 of hydrocyclone separdlu, :j 302, 303, 304, and 305, the underflow
manifold 340 may be provided with a non-circular portion 340A which, in plan, may
have a substantially kidney-shaped cross section (See Figure 4E). Although shown
as substantially kidney-shaped in cross-section, non-circular portion 340A may have
25 any cross-sectional configuration that ensures that its cross sectional area at the
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blal~dal d circular portion 340B ,eh,ai"s s~ "lially ull~;hal~yed as the non-circular
portion 340A of u"de, nOw manifold 340 p~cses the head 117 of se,.,~, alor:i 302 - 305,
despite the limited space available. It should also be appreci~ed that the underflow
manifold 340 and overflow Illdl ,ir. ~ 330 shown in Figure 4E adjacent head 117 of a
5 se,~,~, dlor may be cast into one piece which inciudes two flow p~s.sAyes therethrough
one for overflow and another for u"de, flow. A one piece casli"y further red~ ~Ges the
cross-sectional area required to by-pass head 117 by manifolds 330 340. If space
lil l lildliGns do not require it non-circular portion 340A need not be provided.
Similarly overflow outlet pipes 370 connect the overflow outlet of each of the
10 separdlo,s 301 - 305 with overflow manifold assembly 330 similar to manifold 340
which exte, lds through top adapter 310. Underflow manifold asse" lbly 340 is
l~rereraL,ly subslanlially larger in cross-sectional area than that of overflow manifold
assembly 330 to acco"", lod~le the relatively larger flow rate of the underflow stream.
For example separalio" apparatus in accordal ,ce with the embodiment of Figures 4A
15 - 4E has been successr.llly used with the cross-sectional area of the underflow
manifold asser"bly 340 being up to four times larger than the cross-sectional area of
the overflow manifold asse",bly 330. Further those sections 340B of underflow
~"a,.irc 340 extending between the underflow outlets of adjace"l se~.ar~lor~ may
increase in diameter from sepal ~lor 301 to separator 305 since the largest volume of
20 flow will occur through underflow manifold 340 adjacel,l the outlet of lowermost
sepa, dlor 305.
The ol ~tsi~ie diameter of housing 300 is preferably less than the inside
didl"eter of the well casing by only the clearance necessary to run the assen,bly into
the well for example a diametrical cleara"ce of one-sixteenth of an inch may be used.
2 5 This " ,ati" ,i~es the did,, ,eter of the housing 300 which in turn maxi" ,i~es the size of
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hydrocycione sepa,dlur~ 301 - 305 thereby maximizing the ca~ acily of the entire
separalor assembly. The well casing diameter may be measured prior to running the
housing into the well to ensure sufficient cleara"ce is prese, ll. Aller"~ /ely housing
300 may cor~",,i.~e the well casing itself which further increases the clia",eter of
5 se,~,a, alor asser, Ibly 313 and increases ~l ~~ci~.
The construction of the se~aralor asser"bly des~iL,ed above is prereraL,ly
simplified by the use of :,la"d~,(J pipe se~iol ,s and ~Idl Idal d de-oiling hydrocyclones
as desc;,iL,ed previously. The specialty parts required may include the top adaplar
310 bottom add~,ler 380 the non-circular portions 340A (if necess~ry) of underflow
10 Illar,irold 340 underflow pipes 360 and 360A and overflow pipes 370. As can be
seen from a con l,~Jdl ison of Figure 3B and Figure 4B adapter 211 as described with
r~rerence to Figure 3B is not required between adjacent hydrocyclone separators in
the assembly configuration of the embodiment des~;, ibed with r~rere"ce to Figure 4B.
In use the inspll~tion and operation of se~.ardlor assembly 313 is as
15 desc; ibed above with rerer~nce to separator assel~,bly 113 which is illustrated in
Figures 3A and 3B. Separalor asse"lbly 313 is capable of substantially greater
ca~.acilythan asser"L,ly 113.
For example asser"blies such as asse",bly 313 having five :,landard sized
hydrocyclones in accordance with the er"bodi"~enl described above have been
20 constructed and tested where the diameter of housing 300 is 5.5 inches and the
length of housing 300 is about 24 feet. Such an assembly is suitable for use in 7 inch
well casing. A cal.~cily of up to 10 000 barrels of production fluid per day can be
achieved with such a five hydrocyclone assembly. The ratio of the cross-sectional
area of the head of hydrocyclones 301 - 305 to the cross-sectional area of the
25 housing 300 is about 0.3 or greater. This ratio is smaller than 0.5 because sla, I.lard-
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W O 97/25150 PCT/GB97/00087sized hydrocyclones were used. It is prererable to maximize this ratio to maximize the
ca,uacily of the se~ar~lor asser, Ibly.
While it is possible to create a modular system by combining two or more
separalor asser"blies 313 with ~uprop,iate Illalli~ld c~""e~lions this becor"es
5 increasingly difficult as the number of hydrocyclone separ~3Lor:, increases. This is
bec~lse the piping and manifolding required P~cse~l-s the space available within
housing 300 particularly at the lower end of the housing 300 for a given well casing
diameter when the number of hydrocyclones ~xr~eds a certain value.
While a pl ere" ed embodiment of the invention has been described
10 modifications thereof can be made by one skilled in the art without departing from the
spirit of the invention.
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