APPARATUS FOR SEPARATING SOLIDS FROM WELL FLUIDS

APPAREIL DE SEPARATION DES SOLIDES DANS LES FLUIDES DE PUITS

English Abstract

In general, presently existing separators for the
effluents of gas and oil wells are large volume, low pressure
devices, which usually rely on gravity for the separation of solids
from produced well fluids. A simple separator for separating solids
and liquids from oil or gas well effluents capable of operating at
high pressures includes an elongated, horizontal tank with an inlet
in one end thereof for receiving well effluent, level control ports
in a side of the tank for maintaining liquid in the tank at a
predetermined level below the longitudinal center of the tank, a
slotted baffle extending downwardly from the top of the tank near
the inlet end for defining an inlet chamber permitting rapid
expansion of the effluent and promoting solids separation, the inlet
chamber being followed by a gravity chamber facilitating gravity
separation of solids, a plurality of perforated plates downstream of
the baffle defining aggregate chambers containing particulate
material for promoting additional solids separation and coalescence
of hydrocarbon liquids and water in the liquid portion of the
effluent, and an outlet chamber downstream of the aggregate chambers
with a gas outlet in the top thereof for discharging gas from the
tank, partitions defining a hydrocarbon discharge basin into which
hydrocarbon liquids overflow for discharge from the tank, and a
water outlet in the other end of the tank beneath the normal
operating liquid level for discharging water from the tank.

French Abstract

Règle générale, les séparateurs actuellemet utilisés pour traiter les effluents des puits de pétrole et de gaz sont des appareils à basse pression d'une grande capacité qui font habituellement appel à la gravité pour séparer les solides des fluides produits dans les puits. Un simple séparateur des solides et de liquides des effluents de puits de pétrole et de gaz, capable de fonctionner à haute pression, comprend un réservoir horizontal, de forme allongée avec une entrée à une extrémité pour la réception des effluents de puits, des orifices de régulation du niveau pratiqués dans un côté du réservoir, afin de maintenir le niveau du réservoir à un niveau prédéterminé sous la ligne centrale longitudinale, un déflecteur à fentes s'avançant vers le bas, depuis la partie supérieure du réservoir, près de l'extrémité du point d'entrée afin de définir une chambre d'entrée permettant l'expansion rapide de l'effluent et favorisant la séparation des solides. Cette chambre est suivie d'une chambre de séparation par gravité facilitant la séparation des solides, de plusieurs plaques perforées placées en aval du déflecteur et définissant des chambres de réception des aggrégats contenant des matières particulaires pour favoriser la séparation de solides additionnels et la coalescence de liquides d'hydrocarbures et d'eau dans la partie liquide de l'effluent et d'une chambre de sortie en aval des chambres de réception des aggrégats comprenant un orifice d'évacuation des gaz pratiqué dans la partie supérieure pour libérer les gaz du réservoir, des cloisons définissant un bassin de sortie dans lequel passent les liquides d'hydrocarbures pour sortir du réservoir et un orifice d'évacuation de l'eau à l'autre extrémité du réservoir, sous le niveau normal du liquide afin d'évacuer l'eau du réservoir.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A separator for separating solids and liquids from oil
or gas well effluent comprising elongated, horizontal tank
means; first inlet means in one end of said tank means for
introducing well effluent into said tank means; level
control means in said tank means for maintaining the liquid
in said tank at a predetermined level below the
longitudinal center of the tank means; slotted baffle means
extending downwardly from the top of said tank means near
said one end, said baffle means extending downwardly beyond
the predetermined level for defining an inlet chamber
permitting rapid expansion of the effluent and promoting
solids separation; a plurality of perforate plate means in
said tank means downstream of the baffle means defining a
gravity separation chamber with said baffle means for
promoting additional solids separation; solids outlet means
in said tank means at the bottom of said gravity separation
chamber, said perforate plate means defining at least one
aggregate chamber for receiving particulate material
adapted to promote additional solids separation, the last
said perforate plate means and the other end of said tank
means defining an outlet chamber downstream of said last
plate means; gas outlet means in the top of said tank means

for discharging gas from said outlet chamber; partition
means in said outlet chamber defining a liquid hydrocarbon
discharge basin for receiving liquid hydrocarbons
overflowing said partition means; hydrocarbon outlet means
in said tank means for discharging liquid hydrocarbons from
said basin; and water outlet means in said other end of
said tank means beneath said predetermined liquid level for
discharging water from said outlet chamber.
2. A separator according to claim 1, wherein said baffle
means includes a plurality of rows of vertically extending
bar means, the bar means in one row being staggered with
respect to the bar means in any adjacent row, whereby
separation of solids, liquids and gases is promoted.
3. A separator according to claim 2, wherein said baffle
means includes upper bracket means for suspending said bar
means from the top of said tank means; lower bracket means
retaining the bottom ends of said bar means; and two
parallel rows of said bar means, the bar means in on row
being staggered with respect to the bar means in the other
said row.
4. A separator according to claim 2, wherein each said
perforate plate means includes a plurality of concentric
circular rows of holes.
5. A separator according to claim 4, wherein the number
of holes in each said perforate plate means is greater
above than below said predetermined level.

6. A separator according to claim 41 including three said
spaced apart, perforate plate means defining a pair of
aggregate chambers, the openings in the first said plate
means being larger than the openings in the other said
plate means.
7. A separator according to claim 6, wherein said
partition means includes first and second parallel, spaced
apart partitions extending transversely outwardly from one
side of said tank means; a third, longitudinally extending
partition interconnecting the other ends of said first and
second partitions, each said partition extending upwardly
beyond said predetermined level; and a notch in one said
partition permitting the overflow of hydrocarbon liquid
into said basin 2.

Description

20~1479
This invention relates to a separator, and in
particular to a separator for the effluents of gas and oil
wells.
Formation fines (sand) from unconsolidated sandstone
reservoirs and artificially introduced sand proppants from
hydraulic fracturing are the primary sources of erosion of
gas and oil well surface production equipment. Wells which
produce sand, for either of the above-mentioned reasons,
are not only dangerous, but usually very costly to
produce. For example, a well having a surface flowing
pressure of 7 MPa, perforated at a depth of 1,000 meters
and producing S liters of sand and 30,000 cubic meters of
natural gas per day through 60 mm tubing effectively
becomes a one kilometer long high pressure sand blaster.
Such a quantity of minimum sand production can easily cut
through surface piping and facilities in relatively short
order. Of course, the high pressure rupturing of piping by
erosive materials constitutes a real danger to oil field
workers. The danger is even greater when the well contains
hydrogen sulphide. Often, the problem of erosion is so
acute that wells are shut down indefinitely.
As more and more oil and gas reserves are exploited,
the hydraulic fracturing of wells will undoubtedly become
more common. After a well has been fractured, it is
normally flowed to clean up and is subsequently tested for

2041~
~ production. Solid returns are at a maximum during the
clean up flow, the purpose of which is to recover any of
the proppants which have not "healed" into the formation.
Other than actual solids, partial solids such as
asphaltenes constitute a source of production difficulty.
Production of this type of solid creates a problem, because
the substances tend to become gasified and migrate to the
top of the separator and into the scrubbed gas stream.
Consequently, the glycol used in dehydrators at the well
head can become contaminated, the controls in oil well
production facilities can become blocked or production
chokes become clogged.
Examples of separators for use with oil and gas wells
are disclosed by Canadian Patents Nos. 806,472, issued to
R.E. McMinn on February 18, 1969 923,826, issued to E.H.
Piner Jr. on April 3, 1973; 933,471, issued to F.L. Murdock
Sr., on September 11, 1973; 1,024,903, issued to F.L.
Murdock Sr., on January 24, 1978 and 1,188,613, issued to
J. Pielkenrood on June 11, 1985, and U.S. Patents Nos.
2,601,903, issued to R.W. Erwin on July 1, 1952 and
4,673,500, issued to R.A. Hoofnagle et al on June 16, 1987.
Without discussing the specifics of this patent
literature, at present, the only available surface erosion
control devices are the so-called "surge-tank" or
"knock-out" vessels. Such devices usually rely on gravity

20~14~9
- and large capacity tanks for separating solids from
produced well fluids. The principle difficulty with such
devices is the low operating pressures of the vessels, and
poor or inadequate internal designs. The separators in
question are effective for low pressure wells, because the
vessels used have typical operating pressures below 700
kPa. Moreover, low pressure tanks cannot readily be
incorporated into permanent production facilities.
The object of the present invention is to provide a
solution of the above identified erosion problems in the
form of a relatively simple separator for effectively
separating solids from well fluid effluents, even under
high pressures.
Accordingly, the present invention relates to a
separator for separating solids and liquids from oil or gas
well effluents comprising elongated, horizontal tank means;
first inlet means in one end of said tank means for
introducing well effluent into said tank means; level
control means in said tank means for maintaining the liquid
in said tank at a predetermined level below the
longitudinal center of the tank means; slotted baffle means
extending downwardly from the top of said tank means near
said one end, said baffle means extending downwardly beyond
the predetermined level for defining an inlet chamber
permitting rapid expansion of the effluent and promoting

20~L~4~9
solids separation; a plurality of perforated plates means
in said tank means downstream of the baffle means defining
a gravity separation chamber with said baffle means for
promoting additional solids separation; solids outlet means
in tank means at the bottom of said gravity separation
chamber, said perforate plate means defining at least one
aggregate chamber for receiving particulate material
adapted to promote additional solids separation, the last
said perforate plate means and the other end of said tank
means defining an outlet chamber downstream of said last
plate means; gas outlet means in the top of said tank means
for discharging gas from said outlet chamber; partition
means in said outlet chamber defining a liquid by
hydrocarbon discharge basin for receiving liquid
hydrocarbons overflowing said partition means; hydrocarbon
outlet means in said tank means for discharging liquid
hydrocarbons from said basin, and water outlet means in
said other end of said tank means beneath said
predetermined liquid level for discharging water from said
outlet chamber.
The invention will be described in greater detail with
reference to the accompanying drawings, which illustrate a
preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, partly sectioned, side
elevational view of a separator in accordance with the
present invention;

2 ~
Figure 2 and 3 are partly sectioned, end views of the
separator of Fig. 1, as seen from the left and right,
respectively of Fig. 1
Figure 4 is a front view of a solids baffle used in
the separator of Figs. 1 to 3;
Figure 5 is a cross section taken generally along line
V-V of Fig. 4; and
Figure 6 is a front view of an aggregate retainer
plate used in the separator of Figs. 1 to 3.
With reference to the drawing, the separator of the
present invention includes an elongated, horizontal tank
generally indicated at 1 defined by a cylinder 2 with
closed convex ends 3 and 4. The tank 1 is supported by a
pair of legs 5. Well effluent is introduced into the tank
1 through an inlet pipe 7 in the end 3. A baffle 8
suspended from the top of the cylinder 2 defines the
trailing or downstream end of an inlet chamber 9. A
pressure relief vent 11 containing a pressure relief valve
(not shown) is provided at the top of the inlet chamber 9,
and a solids cleanout pipe 12 is provided in the bottom of
the cylinder 2.
As shown in Figs. 4 and 5, the baffle 8 is defined by
a pair of parallel rows of vertical bars in the form of
small diameter tubes 14 extending between brackets defined
~y parallel, arcuate to plates 15 and a straight,

2~Al~
horizontal bottom plate 16. The tubes 14 in one row are
staggered with respect to the tubes 14 in the other row.
The inlet chamber 9 is followed in the direction of
material flow by a gravity chamber 17, the bottom of which
contains a principal solids outlet 8 and a second solids
cleanout pipe 19. A port 21 for a temperature probe (not
shown) is provided in the side of the gravity chamber 17,
and a cleanout port 22 and differential pressure gauge port
23 are provided in the top thereof. The trailing or
downstream end of the gravity chamber 17 is defined by a
perforate disc or plate 24, which is followed by two
additional plates 25 and 26. The plates 24, 25 and 26 are
parallel and spaced apart, defining chambers 28 and 29 for
receiving particulate material or aggregate (not shown)
which is loaded into the chambers via a top inlet pipe 30.
A rectangular projection 31 (Figs. 1 and 6) on the top
center of the disc 25 divides the inlet pipe 30 into two
passages. Solids can be removed from the chambers 28 and
29 through outlets 33 and 34 in the bottom of the cylinder
2.
Each of the plates 24, 25 and 26 includes an annular
mounting rim 36 (Fig. 6), and a plurality of concentric
circular rows of openings 37. The first plate 24 contains
openings 37 which are relatively large in diameter (9.55
mm).

The second and third plates 25 and 26 contain smaller
openings (6.4 mm diameter). The number of openings 37 in
the upper ends of the plates 24, 25 and 26 is greater than
the number in the lower ends of the plates. The plates 24,
25 and 26 also promote the coalescing of oil droplets, and
the separation of sand from the liquids flowing
therethrough. The particle size of the aggregate in the
first aggregate chamber 28 is larger than the particle size
of the aggregate in the chamber 29. Preferably the
aggregate or particulate material in the chambers 28 and 29
is granite stucco stones.
The plate 26 defines the upstream end of a final
gravity separation and outlet chamber 39, which contains a
differential pressure gauge port 40 in the top thereof.
Liquid level control outlets 42 are provided in one side of
the cylinder for maintaining the operational level of the
liquid indicated by line 43 (Figs. 1 to 3) below the center
of the tank, but above the bottom of the baffle 8. Four
gauge column ports 45 are also provided in one side of the
tank, for the attachment of site glasses. Gas is
discharged from the chamber 39 via a mist pad 46 suspended
from the top of the tank a holder 47, and an outlet pipe
49. Water is discharged from the end 4 of the tank via an
L-shaped outlet pipe 50, one arm 52 of which extends
downwardly in the tank close to the bottom thereof. A

2Q~4~9
- alternative water dump controller and cleanout pipe 53 is
provided in the end 4 above the pipe 50. Hydrocarbon
liquid is discharged from the chamber 39 through a bottom
outlet 55. A third solids cleanout pipe 56 is provided in
the bottom of the cylinder 2 downstream of the hydrocarbon
outlet 55.
A pair of transversely extending partitions 58 and 59
(Figs. 2 and 3, respectively) and a longitudinally
extending partition 60 define three walls of a hydrocarbon
basin 62. A notch 63 (Fig. 3) is provided in the partition
59, so that the latter acts as a weir, permitting the
overflow of hydrocarbon liquids from the outlet chamber
into the basin 62. As mentioned above, the hydrocarbon
liquids are discharged via the bottom outlet 55.
Because the tank 1 is designed to operate under high
pressures (of 10 MPa and higher), reinforcing pads are
provided around the principal inlets and outlets.
In operation, well effluent enters the inlet chamber 9
via the inlet pipe 7. The sudden expansion of the well
effluent reduces flow velocity and initiates the sand
drop-out process. Moreover, by reducing the flow velocity,
the erosive effect of the sand is reduced, and both sand
and liquid descend in the tank 1. The effluent encounters
the baffle 8 which absorbs some of the erosive shock of
well debris, and changes the flow direction which promotes

2~41~79
phase separation. The baffle 8 also causes separation of a
large volume of sand. During passage through the baffle 8,
oil droplets are coalesced. Following passage of the well
effluent through the baffle 8, additional gravity
separation of sand occurs in the chamber 17.
The effluent, containing a reduced sand concentration
passes through the particulate material in the aggregate
chambers 28 and 29. Impingement of the effluent upon the
particulate material in the cham~ers facilitates solid
separation. Moreover, because of the large surface area of
the materials in the chambers 28 and 29, coalescence
occurs, promoting separation, hydrocarbon liquids and water
phases. Additional aggregate chambers can be provided, the
number of chambers being dictated by flow volume, solids
content and the required fluid separation capabilities. It
is worth noting that trapped grains of sand in the chambers
28 and 29 enhance rather than impede sand separation. The
particular material can be removed from the chambers 28 and
29 through the outlets 34 and 35 for cleaning or
replacement.
Material entering the outlet chamber 39 is further
separated when hydrocarbon liquids flow into the basin
defined by the partitions 58, 59 and 60. Gases are
discharged through the outlet pipe 49, hydrocarbon liquids
are discharged through the outlet pipe 5 and water is

2 ~
discharged through outlet pipe 50 to complete the
separation process.
Operation under relatively high working pressures
reduces the need for choking of the effluent upstream of
the tank 1, thereby reducing hydrate difficulties created
by the cooling effects from the pressure drop due to
choking. Hydrate difficulties are further reduced by
operating the tank at pressures close to well head
production pressures.
la

Representative Drawing