Note: Descriptions are shown in the official language in which they were submitted.
CA 02859529 2014-08-15
OIL PRODUCTION SYSTEM
FIELD
[0001] Surface equipment and methods used at oil and gas wells to produce
and store
fluids at a well site.
BACKGROUND
[0002] The inventor has designed and patented several wellsite production
machines
including Canadian patent nos. 1274785, 2025925 and 2226042. While these
designs have
been successful, high pressure production packages have become quite expensive
and complex.
SUMMARY
[0003] Various components of a wellsite production machine are disclosed
including
separator, combination separator and oil storage tank, flare stack assembly
and method of
manufacture.
[0004] In an embodiment, there is disclosed a wellsite production machine.
The wellsite
production machine may comprise a separator connectable to a wellhead, the
separator having a
liquids discharge line and a oil discharge level, an oil storage tank having a
liquids input port to
which the liquids discharge line is connected; and the storage tank having a
high level line
established by a high level detection apparatus, the oil discharge level of
the separator being at or
above the high level line of the storage tank so that liquids in the separator
may flow by gravity
into the storage tank.
[0005] In another embodiment, there is disclosed a separator, which may be
used with the
disclosed wellsite production machine. The separator may comprises a vapour
tight enclosure, a
standpipe extending vertically within the vapour tight enclosure, the
standpipe having an upper
part and a lower part, an inlet line for fluids from a well, the inlet line
opening into the upper part
of the standpipe for discharge of fluids from the well into the standpipe, a
water level detector in
the vapour tight enclosure that defines a water-oil level within the vapour
tight enclosure, a water
dump control responsive to the water level detector to open when the water
level exceeds the
defined water-oil level, the lower part of the stand pipe extending below the
water-oil level, an
oil discharge line having an opening for receiving oil from the vapour tight
enclosure and above
the water-oil level and a vent for gases to escape from the vapour tight
enclosure.
CA 02859529 2014-08-15
[0006] In another embodiment, there is disclosed a flare stack assembly,
which may be
used with the disclosed wellsite production machine. The flare stack assembly
may comprise a
flare stack, a dropout tank, an inlet line having an opening into the dropout
tank;, the inlet line
being connectable to a separator, a detonation arrestor line extending out of
the dropout tank
through a detonation arrestor and downward into the flare stack and a fluids
return line between a
bottom of the flare stack and the dropout tank.
[0007] In an embodiment of a wellsite production machine installation
method there is
disclosed fabricating concrete support slabs, a separator, a storage tank and
height adjustable
support posts, transporting the fabricated concrete support slabs, separator,
storage tank and
height adjustable support posts to a wellsite, mounting the separator and
storage tank on the
concrete support slabs and height adjustable support posts and levelling and
adjusting the vertical
location of each of the separator and the storage tank using the height
adjustable support posts.
BRIEF DESCRIPTION OF THE FIGURES
[0008] There will now be described preferred embodiments of a wellsite
production
machine with reference to the figures by way of example, in which like
reference characters
denote like elements and in which:
[0009] Fig. 1 shows a side view of a wellsite production machine including
flare stack
assembly, separator and oil storage tank;
[0010] Fig. 2 shows atop view of the wellsite production machine of Fig.
1, including
water storage tank;
[0011] Fig. 3 is a detail from Fig. 1 showing a flare stack assembly;
[0012] Fig. 3A is a top view detail showing an example of a flare stack
assembly with a
compressor for discharging gas to a sales line;
[0013] Fig. 3B is atop view detail of an alternative embodiment of a flare
stack assembly
with a compressor for discharging gas to a sales line;
[0014] Fig. 4 is a detailed side view from Fig. 1 showing a separator;
[0015] Fig. 4A is a detailed side view showing a separator with a syphon
water dump;
[0016] Fig. 5 is a detail top view from Fig. 2;
[0017] Fig. 5A is a top view of an alternative embodiment of the tanks in
Fig. 5, in which
a tank is divided into oil and water compartments; and
CA 02859529 2014-08-15
[0018] Fig. 5B is a side view of an alternative embodiment of the tanks in
Fig. 5, in
which there is at least an additional tank connected by an equalizing line.
DETAILED DESCRIPTION
[0019] A wellsite production machine is disclosed as illustrated in Figs.
1 and 2. Novel
components are described in detail. Various lines connect the main components
and these are not
described in detail since they are conventional. The lines may thus comprise
connected pipes
(lines), fittings, isolation valves, relief valves and gauges as are
conventionally used and in many
cases required by applicable safety regulations. A separator 10 is connectable
to a wellhead 12
by a line 14 and operates in conjunction with an oil storage tank 16 fed
gravitationally by the
separator 10, and where the oil is wet (which is usual) with a water storage
tank 18, also fed
gravitationally by the separator 10. Line 14 may be a conventional line or may
be an insulated
line. Insulating the line 14 saves well production heat reducing the need to
add further heat at
the separator. Insulating the line also prevents waxing and freezing problems.
In some
embodiments, neither the separator 10, oil storage tank 16 or water storage
tank 18 need be
exactly as shown. For example, in some embodiments, the shape, orientation and
relative
location of the items 10, 16 and 18 may vary depending on the design choice.
Multiple oil and
multiple water tanks may be used if desired. Multiple oil tanks may be
connected with oil
equalizing lines and multiple water tanks may be connected with water
equalizing lines. A
divider may divide a single tank into a water storage compartment and an oil
storage
compartment if desired. Fig. 5A shows a tank 17 divided into oil and water
compartments by a
divider 19. In the embodiment shown in Fig. 5A an additional oil storage tank
16 is used
alongside the divided tank, and an oil equalizing line 140 and gas equalizing
line 142 connect the
oil compartment of the divided tank to the oil tank 16. An opening (not shown)
at the top of the
divider may allow gas pressure equalization between the water and oil
compartments. Fig. 5B
shows an embodiment in which multiple oil storage tanks are used. A first oil
storage tank 16 and
a second oil storage tank 16A are connected by an oil equalizing line 144 and
a gas equalizing
line 146. Multiple water tanks may be connected similarly.
[0020] The separator 10 is formed of a vapour tight enclosure. The
separator 10 may be
a vertically oriented cylinder with domed ends (long axis vertical), but other
designs may be used
and in some cases the separator 10 may be horizontally disposed, but this is
not preferred. The
CA 02859529 2014-08-15
separator 10 may be made of conventional materials and in some embodiments may
need only
14.9 psi pressure rating. The embodiment of the wellsite production machine
shown has an
advantage due to its reliance on gravity to feed the oil storage tank in that
a relatively low
pressure rating such as 14.9 psi is required on the separator 10, oil storage
tank 16 and water
storage tank 18. Tanks may be designed to hold higher pressures than are
required, for example
in an embodiment tanks designed for 35 psi are used, but with 14.9 psi relief
valves on them to
stay as an atmospheric tank rating. In normal operation the pressures in the
system are below the
relief valve pressures so no vapors are lost to the atmosphere through the
relief valves.
[0021] Referring to Fig. 4, the separator 10 has a liquids discharge line
20 and an oil
discharge level. The oil discharge level may be anywhere in the separator 10
providing it is
above any water-oil level, but may be in an upper part of the separator 10 as
created by the lip 22
on oil pan 24 for oil to spill over from the separator 10 into the oil pan 24
. The liquids discharge
line 20 may have an opening 26 forming an exit from oil pan 24 below lip 22
for oil to be
discharged from the separator 10 into the oil storage tank 16.
[0022] The separator 10 includes a standpipe 56 extending vertically
within the vapour
tight enclosure. By vertically here is meant functionally vertically. The
standpipe 56 could be
placed on an angle but would still extend vertically. The standpipe 56 has an
upper part 58 and a
lower part 60. The inlet line 14 is connectable to a well (not shown) and
includes conventional
fittings, valves, gauges and controls as would be found on typical production
facility lines from
wells. The inlet line 14 opens into the upper part 58 of the standpipe 56 for
discharge of fluids
from the well into the standpipe 56. A water level detector 64 in the
separator 10 defines a
water-oil level 67 within the vapour tight enclosure of the separator 10. A
water dump control 68
is responsive to the water level detector 64 to open when the water level
exceeds the defined
water-oil level 67. Water drains by gravity along lines 70 and 71 to the water
storage tank 18.
Valve 73 may be provided on an extension of line 71 past line 70 to allow for
draining of the
separator 10, and valve 75 may be provided on line 71 to isolate line 71 from
the separator 10
when needed.
[0023] The head of water and oil in the separator 10 ensures sufficient
pressure to force
the water into the water tank 18. The lower part 60 of the stand pipe 56
extends below the water-
oil level 67. A vent 72 is provided for gases to escape from the vapour tight
enclosure. Gases
are preferably directed via the vent 72 along line 74 to a flare stack
assembly 76. A conventional
CA 02859529 2014-08-15
pressure relief valve (not shown) is also provided on the separator 10 in
accordance with
applicable safety standards. Gases from the top of stand pipe 56 may be
directed along line 75 to
the flare line 74. In an embodiment line 74 uses 8" diameter pipe to allow
high volumes of gas,
for example up to 10 million scfd, to be sent to the flare when needed without
causing elevated
back pressure on the separator and storage tanks. In an embodiment, the 8"
line allows large
volumes of gas to be flared without making the separator and storage tanks
pressures more than
PSI.
[0024] Oil storage tank 16 is preferably a horizontally disposed
cylindrical tank with
domed ends as shown. If the oil storage tank 16 were vertically oriented, then
the separator 10
would have to be correspondingly higher to allow the separator 10 to drain by
gravity into the oil
storage tank 16. However, at some additional cost, the oil storage tank 16
could be formed of
multiple vertically oriented tanks or even a coiled pipe. The oil storage tank
16 has a liquids
input port 28 to which the liquids discharge line 20 is connected. Within the
oil storage tank 16
is a high level line 30 established by a high level detection apparatus 32.
When oil in the tank
reaches the high level line 30, the high level detection apparatus 32 shuts
off a valve 36 on the
line 14 to prevent further fluids from the well from entering the separator
10. The oil discharge
level of the separator is at or above the high level line 30 of the storage
tank 16 so that liquids in
the separator 10 may flow by gravity into the storage tank 16. Water that has
accumulated in the
oil storage tank 16 may be retrieved via recycle line 118.
[0025] The separator 10 may be mounted above an enclosure or housing 34
that provides
environmental protection for controls, valves and gauges for example forming
part of meter run
35. The meter run 35 measures how much gas is going to the flare on line 74.
Various meters
can be used. This is required to determine the amount of money to pay the
government as carbon
tax. If a compressor is used, the meter run 35 could be on the discharge of
the compressor. In an
embodiment an ultrasonic gas meter is used that does not rely on differential
pressure to obtain a
reading. The ultrasonic meter uses sound waves to determine how much gas is
passing through
the flare line.
[0026] The enclosure 34 may be circular, insulated, made of metal such as
steel and
welded to the separator 10. A heat tracing system 112 may also be used to
circulate fluid through
the critical lines and prevent freezing. Water storage tank 18 may be
connected via a line 40 to a
water outlet 42 in the separator 10. There may be a water level operated dump
mechanism 44 in
CA 02859529 2014-08-15
the separator 10 for dumping water from the separator 10 into the water
storage tank 18. Any
suitable or conventional water level operated dump mechanism may be used.
[0027] The separator 10 in some embodiments need not entirely contain the
standpipe 56.
The upper part 58 of the standpipe 56 may extend out of and above the vapour
tight enclosure of
the separator 10. The function of the upper part 58 of the standpipe 56 is to
provide a head of
fluid from the well so that the fluid from well, which comprises water and
oil, is driven below
the standpipe 56 and out into the water that accumulates in the lower part of
the separator 10. A
heater 80 is located within the vapour tight enclosure of the separator 10
below the water-oil
level 67. The heater 80 may in some embodiments be any suitable heater, but
may incorporate a
burner tube 82 in which gases collected from the vapour tight enclosure are
burned. The gases
may be supplied to the heater 80 from the vent 72 along line 84. The gases may
also be supplied
to a desiccant drying tower (not shown) via line 114 or a sweetening tower
(not shown) via line
116. A coalescing hood 79 may be provided above the heater 80. The purpose of
the coalescing
hood 79 is to assist in coalescence of water droplets in a water-in-oil
emulsion or oil droplets in
an oil-in-water emulsion that descends down the standpipe 56 into the water
dominant part of the
separator 10. As the oil emerges in the water section, the oil droplets
coalesce and move upward.
The hood 79 forms a barrier to movement of the oil and water emulsion so that
the fluid has a
prolonged travel time in the water dominant part of the separator 10. In
another embodiment the
separator has insulation outside of the vapor tight enclosure of the
separator, with a space
between the vapor tight enclosure and the insulation, for example of 1.5", all
the way to the top
of the separator. Flameless heaters mounted in the bottom section stand of the
heater provide heat
that rises up within the space between the separator and the insulation and
out the top to keep the
separator warm with no fire tube with controls needed.
[0028] Another version of the separator 10 is shown in Fig. 4A. In Fig.
4A, the water
dump is provided by a syphon system. In the syphon dump, water discharge line
71 is connected
to a syphon loop 77 that runs up the side of the separator 10 then back down
again and out to the
water tank 18. The line 71 terminates in the water tank 18 at a level chosen
so that when water is
above a pre-defined level in the separator 10, the water will spill out into
the water tank 18. This
level may be adjusted by a sliding sleeve 81 that slides in a tube 83
extending upward from the
top of the syphon loop 77. A line 85 extends from the top of the tube 83 to
the top of the
separator 10. The sleeve 81 is closed at the top, and the height of the column
of fluid in the
CA 02859529 2014-08-15
syphon loop 77 may be adjusted by moving the sleeve 81 up and down. When the
sleeve 81 is
fully extended upward the syphon may be opened to the separator 10, for
example for removing
an air lock or allowing the syphon to drain. In a part of the separator that
may be referred to as a
Hay section 21, a separate screen 66 may be provided that supports wood strips
or the like in the
oil to help make oil droplets coalesce. The storage tanks can operate at the
same pressure
(preferably in the range of 5 to 10 psi) that the separator operates at, so
that valves are not needed
to hold pressure between the separator and the tanks. The elevated position of
the separator
allows fluids to run out by gravity instead of pushed out by pressure, with no
controls being
needed. The pressure may be kept equalized by piping that allows gas to move
around as needed.
[0029] Gases
from the vent 72 may be supplied along line 74 to a sales line (not shown)
or to the flare stack assembly 76. The line 74 preferably slopes downward away
from the
separator 10 down to the flare stack assembly 76. The slope may be for example
1 in 150, so
that liquids condensing in the line 74 are conveyed towards the flare stack
assembly 76. As
shown in Fig. 3, the flare stack assembly 76 may comprise a liquids drop out
tank 90, flare stack
92 and detonator arrestor 94 on detonation arrestor (DA) line 96 between the
liquids dropout
tank 90 and flare stack 92. Flare stack 92 may be conventional, with
conventional support (not
shown) and ignitor 95. The DA line 96 is provided with a receiving port 98 for
collecting gases,
and a portion 99 that offsets the detonation arrestor 94 so that the
detonation arrestor 94 is not
gravitationally in line with the flare stack 92. The portion 99 is also sloped
downward so that
fluids condensing after the detonation arrestor 94 drain towards the flare
stack 92, to the bottom
of flare stack 92, then through chamber 100 and fluids return line 102 into
liquids dropout tank
90. This acts to protect the DA from plugging. Chamber 100 may be formed as
the upper part of
dropout tank 90, and separated from it by a plate (not shown). Fluids collect
on plate (not shown)
then flow into the return line 102, which opens out into both the tank 90 and
chamber 100. The
flare system may comprise a flare knockout and flare combined into one so that
it is more
effective and more economical to purchase and operate. The flare may be
equipped with a self
adjusting flare tip that maintains complete combustion of the flare gas for
smokeless burning
when flaring and holds back pressure on the whole system so it all runs at the
same pressures.
For example, the Prism Self Adjusting Sonic FlareTM automatically adjusts the
exit opening to
allow gas to be released while maintaining 5 PSI upstream so that the whole
system such as the
Separator-Treater and storage tanks and all the piping all run at 5 PSI right
out to the sonic flare
CA 02859529 2014-08-15
tip that is holding the pressure back on the whole system. The self adjusting
flare uses the 5 PSI
pressure to create sonic velocity around the cylindrical head to create a huge
influx of air that
completely burn the hydrocarbon vapor very efficiently and leaves no smoke
from the flame.
[0030] For an application where there the flare used does not hold back
pressure, an
inflatable back pressure will be used to maintain pressure, for example 5 PSI,
on the whole well
site and the back pressure will release to flare the extra gases to be burnt.
[0031] Gas from the flare line 74 may be provided to a fuel conditioning
skid that
separates the liquid out of the gas and further dries the gas with dessicant
beads. The fuel from
the skid may be provided to a fuel gas system to operate engines and heaters
at the well site. The
skid also eliminates salts and contaminants from the fuel gas system to reduce
residue on engine
valves and pistons and to avoid contaminating and plugging gas heaters. In an
embodiment, a gas
driven variable speed pump jack drive system may be provided, operating using
the gas from the
fuel conditioning skid instead of burning diesel in generator sets or
requiring power lines to be
provided. Load sensors may control the speed of the drive to ramp hydraulic
motors up and
down to manage strioke speeds and rod load stress.
[0032] Gas from the flare line 74 may also be provided to a sales line as
shown in Fig.
3A. In Fig. 3A, the flare stack assembly 76 is designed as shown in Fig. 3,
except that a line 120
extends from the tank 90 or 100 to a compressor station 122. Compressor
station 122 includes a
compressor pump 124 driven by an engine 126. The compressor pump may for
example be a
reciprocating or screw type pump. In an embodiment the compressor pump may be
or include a
self adjusting variable speed compressor. In an embodiment the pump may be a
Prism Booster
ScrewTM. In an embodiment where there is no sales line, the compressor may be
omitted. The
engine 126 has a cooling unit 128 with radiator 129, cooling fan 130 and
clutch 131. Gas
pumped by the compressor pump 124 is passed through circulator bypass 132 and
cooler 134 to a
line 136 that goes out to a sales line (not shown). The pump 124 compresses
the gas to a higher
pressure so that it can be pumped into the sales line, while the circulator
132 helps drop liquids
out of the gas. Cooler 134 is used to cool the gas, which has been heated by
the pump 124. The
cooler 134 may be a combi-cooler. An optional sweetener 138 with granular
sweetening
compound may be connected to line 120 by a relief bypass line (not shown) in
case of emergency
shut down failure. In an embodiment the sweetener 138 is connected to line 120
to sweeten the
gas heading to pump 124 to strip the sulfur out of the gases before they are
sold in the pipe line.
CA 02859529 2014-08-15
As the equipment is operating at less than 14.9 PSI, low cost sweetening tanks
can be used.
Atmospheric designed sweeteners are much cheaper to purchase and maintain
compared to
registered pressure vessels. Fig. 3B shows an alternative embodiment of
compressor station
122. In Fig. 3B a building enclosure 123 surrounds the compressor 124 but
excludes the engine
126 which sits outside. Compressor 124 is in line with engine 126 and
compressor cooler 133 is
located between the engine and compressor outside the enclosure. Gas exiting
the compressor
passes through a coalescing filter 137 to remove liquids before the gas passes
to a sales line (not
shown).
[0033] The well site production machine may be installed in an efficient
method using
pre-fabricated concrete slabs 103, 104, 105 and height adjustable support
posts 106, 107, which
are sized according to the load they will support. All major components
including the concrete
slabs 10, 204, 105 may be pre-fabricated offsite then transported to the well
site where the well
site production machine is to be installed. The slabs 103, 104 and 105 may be
made of other
construction materials such as steel beams, but concrete slabs are
inexpensive. Thus the concrete
support slabs 103, 104, 105, separator 10, storage tanks 16 and 18 and height
adjustable support
posts 106, 107 may be all fabricated in an off-site location then transported
to a wellsite. At the
well site, the separator 10 and storage tanks 16, 18 may be mounted on the
concrete support slabs
104 and height adjustable support posts 106 and then then the vertical
location of each of the
separator 10 and the storage tanks 16, 18 levelled and adjusted using the
height adjustable
support posts. Manways 108 may be located on the separator 10 and the storage
tanks 16 and 18.
Concrete slabs 104 may also be used to support steps 110 and walkway 112 which
provide
access for personnel to service the top of the tanks. Oil storage tank 16 may
be equipped with a
floating load out hose inside to allow dry oil to be shipped before hitting
wet oil. Oil storage tank
16 may be equipped with a built on LACT unit to record and document oil sold
from the tank for
the oil company, land owner or oil buyers.
[0034] The modular prefabrication method may also be used to install the
flare line 74
and flare stack assembly 76. The flare stack assembly 76, including flare line
74, is first
fabricated off site at any suitable location, then transported to a wellsite
along with the separator
10, tanks 16 and 18 and associated components. At the well site, the
installation method then
proceeds with mounting the flare stack assembly 76 including the flare line 74
on the concrete
CA 02859529 2014-08-15
support slabs 104 and height adjustable posts 106, and adjusting the flare
line 74 with the height
adjustable posts 106 to have a downward slope with increasing distance from
the separator 10.
