SUPERHYDROPHOBIC FLOW CONTROL DEVICE
Technical Field
[0001] The present disclosure relates generally to flow control devices for a
wellbore and, more particularly (although not necessarily exclusively), to a flow
control device having a superhydrophobic surface that can affect fluid flow.
Background
[0002] Various devices can be installed in a well traversing a hydrocarbonbearing
subterranean formation. Some devices control the flow rate of fluid
between the formation and tubing, such as production or injection tubing. An
example of these devices is a flow control device that can control the flow rate of
various fluids into the tubing.
Brief Description of the Drawings
[0003] FIG. 1 is a schematic illustration of a well system having helical flow
control devices with a functionalized surface that can include a superhydrophobic
material according to one aspect.
[0004] FIG. 2 is a perspective view of a helical flow control device
positioned around a tubing string according to one aspect.
[0005] FIG. 3 is an end view of the helical flow control device of FIG. 2 that
includes superhydrophobic material according to one aspect.
[0006] FIG. 4 is a cross-sectional view depicting an example of a fluid
having a greater concentration of a wanted fluid contacting an inner wall of a
helical flow control device coated with a superhydrophobic material according to
one aspect.
[0007] FIG. 5 is a cross-sectional view depicting an example of a fluid
having a greater concentration of an unwanted fluid contacting an inner wall of a
helical flow control device coated with a superhydrophobic material according to
one aspect.
[0008] FIG. 6 is a side view of an example of a contact angle between a
droplet of a liquid and a solid surface with a superhydrophobic material according
to one aspect.
[0009] FIG. 7 is a cross-sectional view of part of a well system having a
gravel pack that includes proppants coated with a superhydrophobic material
according to one aspect.
Detailed Description
[001 0] Certain aspects and features relate to flow control devices with a
surface coated with a superhydrophobic material that can control the flow rate of
fluid between the formation and tubing. The superhydrophobic material on a
surface can change a velocity profile of a fluid contacting the surface. For
example, fluid with a greater concentration of a desired or wanted fluid, such as
oil, can flow with a higher velocity along a superhydrophobic-coated surface.
Fluid with a greater concentration of an undesired or unwanted fluid, such as
natural gas or water, can flow with a lower velocity along a superhydrophobiccoated
surface.
[001 1] Flow control devices according to some aspects can include a
helical flow control device having a tubing with an inner surface that is coated
with a superhydrophobic material. Some fluids, such as oil, can have a high
surface tension. The high surface tension can increase the contact angle
between the superhydrophobic-coated inner surface and oil as compared to the
contact angle between oil and an uncoated inner surface of a tubing. The
increased contact angle results in less surface contact between oil and the
superhydrophobic-coated inner surface compared to the surface contact between
oil and an uncoated inner surface. The decreased surface contact between the
superhydrophobic-coated inner surface and oil can decrease the frictional
resistance experienced by oil flowing along the superhydrophobic-coated inner
surface. The velocity profile of oil flowing along the superhydrophobic-coated
inner surface can increase when the frictional drag is decreased. The velocity
profile of a fluid having a greater concentration of oil flowing along the
superhydrophobic-coated inner surface can also increase as the frictional drag is
decreased. The increase in the velocity profile of the fluid having a greater
concentration of oil can promote the production of that fluid, and thereby oil,
through an inner diameter of the helical flow control device.
[001 2] Other fluids can have a lower surface tension than oil. For example,
natural gas can have almost no surface tension. The low surface tension of
natural gas can cause a large surface area of natural gas to contact the
superhydrophobic-coated inner surface of the tubing. The large surface area of
contact between natural gas and the superhydrophobic-coated inner surface can
cause natural gas flowing along the superhydrophobic-coated inner surface to
experience a high frictional resistance between it and the superhydrophobiccoated
inner surface, which can cause the natural gas to experience a higher
flow resistivity. The higher flow resistivity can decrease the velocity of natural
gas flowing across the superhydrophobic-coated inner surface. Fluids having a
greater concentration of natural gas can also experience a decrease in velocity
as it flows along the superhydrophobic-coated inner surface. The lower velocity
of the fluid having a greater concentration of natural gas can damper or restrict
the production of the fluid, and thereby natural gas, through the helical flow
control device.
[001 3] Other fluids, such as water, can also experience either restriction or
promotion as they flow through the helical flow control device. For example,
features of the helical flow control device having an inner surface that is coated
with a superhydrophobic material can be altered to restrict the flow of other fluids,
such as water. For example, the size of the tube of the helical flow device can be
altered to more greatly restrict a first type of fluid, such as natural gas, and to
restrict less a second type of fluid, such as water or steam.
[0014] Flow control devices according to some aspects can include a
gravel pack assembly with proppants coated with a superhydrophobic material.
Some fluids, such as oil, can experience a lower surface area contact with the
superhydrophobic-coated surface of the proppants, compared to the surface area
contact with uncoated proppants. The decrease in the surface area contact can
cause the velocity profile of oil, and fluid having a greater concentration of oil, to
increase as the fluid passes through the coated proppants towards the production
tubing. The increase in the velocity of the fluid having a greater concentration of
oil can promote the production of the fluid towards the production tubing.
[001 5] Other fluids, such as natural gas, can experience an increase in
frictional resistance between it and the superhydrophobic-coated surface of the
proppants, compared to the frictional resistance between it and uncoated
proppants. The increase in frictional resistance can cause the velocity profile of
natural gas, and fluids having a greater concentration of natural gas, to decrease
as the fluids pass through the coated proppants towards a production tubing.
The decrease in the velocity of fluids having a greater concentration of natural
gas can damper the production of the fluids towards a production tubing.
[001 6] Superhydrophobic material can be a material that repels water at a
contact angle that exceeds one hundred and fifty degrees. Super hydrophobia
can also be referred to as the Lotus effect. Superhydrophobic material can
include nano-composites. Examples of superhydrophobic material can include
manganese oxide polystyrene, zinc oxide polystyrene, precipitated calcium
carbonate, carbon nano-tube structures, and silica-based nano-coating.
[001 7] These illustrative examples are given to introduce the reader to the
general subject matter discussed here and are not intended to limit the scope of
the disclosed concepts. The following sections describe various additional
embodiments and examples with reference to the drawings in which like
numerals indicate like elements, and directional descriptions are used to describe
the illustrative embodiments but, like the illustrative embodiments, should not be
used to limit the present invention.
[001 8] FIG. 1 depicts a well system 100 having helical flow control devices
4 that include superhydrophobic material in an inner wall of the helical flow
control devices 114 according to certain aspects. The well system 100 includes a
bore that is a wellbore 102 extending through various earth strata. The wellbore
102 has a substantially vertical section 104 and a substantially horizontal section
106. The substantially vertical section 104 and the substantially horizontal
section 106 may include a casing string 108 cemented at an upper portion of the
substantially vertical section 104. The substantially horizontal section 106
extends through a hydrocarbon bearing subterranean formation 110.
[00 9] A tubing string 112 extends from the surface into the wellbore 102.
The tubing string 112 can provide a conduit for formation fluids to travel from the
substantially horizontal section 106 to the surface. Helical flow control devices
114 and production tubular sections 116 in various production intervals adjacent
to the formation 110 are positioned around the tubing string 112. On each side of
each production tubular section 116 is a packer 118 that can provide a fluid seal
between the tubing string 112 and the wall of the wellbore 102. Each pair of
adjacent packers 118 can define a production interval.
[0020] Helical flow control devices 114 can allow for control over the
volume and composition of produced fluids. Formation fluid flowing into a
production tubular section 116 may include more than one type of fluid, such as
natural gas, oil, water, steam and carbon dioxide. "Natural gas" as used herein
means a mixture of hydrocarbons (and varying quantities of non-hydrocarbons)
that exists in a gaseous phase at room temperature and pressure and in a liquid
phase or gaseous phase in a downhole environment. Steam and carbon dioxide
can be used as injection fluids to cause hydrocarbon fluid to flow toward a
production tubular section 116. Natural gas, oil, and water be found in the
formation 110.
[0021] A helical flow control device 114 according to some embodiments
can reduce or restrict production of formation fluid having a greater concentration
of an unwanted fluid and can promote the production of fluid having a greater
concentration of a wanted fluid. For example, the helical flow control devices 114
may autonomously restrict or resist production of formation fluid having a greater
concentration of unwanted fluid, such as natural gas, water or steam, from a
production interval. The helical flow control device 114 can also promote the
production of formation fluid having a greater concentration of a wanted fluid,
such as oil, from a production interval. For example, the helical flow control
device 114 can include superhydrophobic material on an inner wall that can
cause the helical flow control device 114 to promote or restrict the flow of
formation fluid based on one or more properties of the formation fluid.
[0022] Although FIG. 1 depicts the helical flow control devices 114
positioned in the substantially horizontal section 106, the helical flow control
devices 114 (and production tubular sections 116) can be located, additionally or
alternatively, in the substantially vertical section 104. Furthermore, any number
of the helical flow control devices 114, including one, can be used in the well
system 100 generally or in each production interval. In other aspects, the helical
flow control devices 114 can be positioned in simpler wellbores, such as
wellbores having only a substantially vertical section. The helical flow control
devices 114 can be positioned in open hole environments, such as is depicted in
FIG. 1, or in cased wells.
[0023] FIG. 2 depicts perspective view of a helical flow control device 114
positioned around the tubing string 112 according to one aspect. The helical flow
control device 114 includes tubing 120 having an inner wall 122. The inner wall
122 may be any shape, including rectangular. The inner wall can be coated with
a superhydrophobic material. The length along the tubing string 112 that the
tubing 120 extends can vary. For example, the coils of the tubing 120 that wrap
around the tubing string 112 can be positioned closely together, so the tubing 120
extends a short distance along the length of the tubing string 112. In another
example, the coils of the tubing 120 can be spaced farther apart, so the tubing
120 extends a greater distance along the length of the tubing string 112.
[0024] FIG. 3 depicts an end view of the helical flow control device 114 of
FIG. 2 that includes a superhydrophobic material 124. The inner wall 122 of the
tubing 120 of the helical flow control device 114 is coated with the
superhydrophobic material 124. The superhydrophobic material 124 can overlay
the inner wall 122 or be embedded within the inner wall 122. The
superhydrophobic material 124 can be on an entire circumferential portion of the
inner wall 122 or on only part of the inner wall 122. The superhydrophobic
material 124 can be screen-printed or otherwise overlaid on the inner wall 122.
In one aspect, the superhydrophobic material 124 is bonded to the inner wall 122
by an adhesive or mechanical coupler. In one aspect, the superhydrophobic
material 124 can include a nano-structure material that is uniform along the x and
y axis of the inner wall 122.
[0025] The superhydrophobic material 124 can allow the helical flow control
device 114 to promote or restrict the flow of fluid based on one or more properties
of the fluid. For example, the superhydrophobic material 124 can increase the
contact angle, and thereby decrease the surface area contact, between the
superhydrophobic material 124 and fluid having a greater concentration of oil.
The decrease in the surface area contact between the fluid having a greater
concentration of oil and the superhydrophobic material 124 can decrease the
frictional drag experienced by the fluid as it flows across the superhydrophobic
material on the inner wall 122. The velocity profile of fluid having a greater
concentration of oil as it flows across the superhydrophobic material 124 on the
inner wall 122 can increase when the frictional drag is decreased. The increase
in the velocity profile of fluid having a greater concentration of oil can promote the
production of the fluid through the helical flow control device 114 towards a
production tubing.
[0026] Other fluids, however, can experience a decreased velocity profile
when flowing along the superhydrophobic material 124 on the inner wall 122. For
example, natural gas can experience an increase in frictional resistance when it
contacts the superhydrophobic material 124, as compared to its contact with an
uncoated surface. The increase in frictional resistance can decrease the velocity
of a fluid having a greater concentration of natural gas flowing across the
superhydrophobic material 124 on the inner wall 122. The decreased velocity of
the fluid having a greater concentration of natural gas flowing along the inner wall
122 can damper the production of the fluid through the helical flow control device
114 towards a production tubing.
[0027] Other fluids, such as water, can also experience a decreased
velocity profile when flowing along the superhydrophobic material 124 on the
inner wall 122. The superhydrophobic-coated tubing 120 of the helical flow
control device 114 can increase the frictional drag experienced by water flowing
along the inner wall 122 while decreasing the frictional drag experienced by oil
flowing along the inner wall 122.
[0028] In another aspect, additional surfaces that are part of a flow path to
a production tubing can be coated with a superhydrophobic material. For
example, sand control screen assemblies can be coated with a superhydrophobic
material.
[0029] FIG. 4 depicts a cross-sectional view of an example of a helical flow
control device 200 that includes tubing 202 that has a superhydrophobic-coated
inner wall 204 and a fluid 206 having a greater concentration of a wanted fluid
flowing within an inner diameter of the tubing 202. The fluid 206 that flows within
the inner diameter of the tubing 202 can experience a decrease in frictional drag
with the superhydrophobic-coated inner wall 204. The decrease in frictional drag
can increase the velocity of the fluid 206 along the superhydrophobic-coated
inner wall 204 of the tubing 202. The increased velocity of fluid 206 having a
greater concentration of the wanted fluid flowing within the inner diameter of the
tubing 202 can promote the production of the fluid 206 having a greater
concentration of the wanted fluid through the helical flow control device 200
towards a production tubing. In one aspect, the wanted fluid can be oil.
[0030] FIG. 5 depicts a cross-sectional view of a helical flow control device
300 that includes tubing 302 that has a superhydrophobic-coated inner wall 304 a
fluid 306 having a greater concentration of an unwanted fluid flowing within an
inner diameter of the tubing 302. The fluid 306 that flows within the inner
diameter of the tubing 302 has a large surface area of contact between it and the
superhydrophobic-coated inner wall 304. The large surface area of contact can
increase the frictional resistance between the fluid 306 and the
superhydrophobic-coated inner wall 304. The increase in frictional resistance
can decrease the velocity of the fluid 306 flowing along the superhydrophobiccoated
inner wall 304 of the tubing 302. The decrease in the velocity of the fluid
306 flowing within the inner diameter of the tubing 302 can damper the
production of the fluid 306 having a greater concentration of the unwanted fluid
through the helical flow control device 300 towards a production tubing. In one
aspect, the unwanted fluid can be one or more of water, natural gas, or steam.
[0031] FIG. 6 depicts a side view of an example of a contact angle between
a liquid droplet 400 and a superhydrophobic solid surface 402. The liquid droplet
400 rests on a superhydrophobic solid surface 402 and is surrounded by a gas
404. The contact angle 406 is formed by the liquid droplet 400 at the three-phase
boundary where the liquid droplet 400, the gas 404, and the solid surface 402
intersect. In one aspect, a superhydrophobic surface can be defined as a surface
in which the contact angle between the solid surface 402 and a droplet of water
exceeds one hundred and fifty degrees. As the contact angle between the liquid
droplet 400 and the solid surface 402 increases, the surface area contact
between the liquid droplet 400 and the solid surface 402 decreases.
[0032] FIG. 7 depicts a cross-sectional view of part of a well system with a
flow control device that includes a gravel pack 502 installed between a tubing
string 504 and a formation 506. The tubing string 504 can provide a conduit for
formation fluids to travel from the formation 506 to the surface. The tubing string
504 also includes additional flow control devices 507. The gravel pack 502
includes proppants 508. The proppants 508 are coated with a superhydrophobic
material. The coated proppants 508 can allow for control over the volume of
produced fluids. For example, the coated proppants 508 can autonomously
restrict or resist production of formation fluid having a greater concentration of
unwanted fluid, such as natural gas or water. For example, as formation fluid
having a greater concentration of natural gas, flows from the formation 506
through the coated proppants 508, the formation fluid can experience an increase
in frictional resistance between it and the coated proppants 508. The increase in
frictional resistance can slow the velocity of the formation fluid through the
spaces between the proppants 508 of the gravel pack 502. The decrease in
velocity of the formation fluid flowing through the gravel pack 502 can limit the
amount of formation fluid having a greater concentration of natural gas entering
the tubing string 504 from the formation 506. The formation fluid can enter the
tubing string 504 via the flow control devices 507.
[0033] The coated proppants 508 can also autonomously promote the
production of fluid having a greater concentration of a wanted fluid, such as oil.
As formation fluid having a greater concentration of oil flows from the formation
through the coated proppants 508, the formation fluid can experience a decrease
in frictional resistance between it and the coated proppants 508. The decrease in
frictional resistance can increase the velocity of the formation fluid having a
greater concentration of oil through the spaces between the proppants 508 of the
gravel pack 502. The increase in the velocity of the formation fluid as it moves
through the gravel pack 502 can increase the amount of formation fluid having a
greater concentration of oil entering the tubing string 504 from the formation 506.
The formation fluid can enter the tubing string 504 via the flow control devices
507. In one aspect, the flow control devices 507 can be coated with a
superhydrophobic material.
[0034] The gravel pack 502 can be installed within the wellbore by pumping
the coated proppants 508 downhole along the length of the wellbore. The coated
proppants 508 can have a decreased frictional resistance between the coated
proppants 508 and the wellbore 500 and the tubing string 504. The decrease in
friction between the coated proppants 508 and the wellbore 500 and the tubing
string 504 can aid in the installation of the gravel pack along long intervals within
the wellbore.
[0035] In one aspect, a wellbore subassembly can include a device having
a production flow path toward a production tubing. The production flow path can
include a superhydrophobic coating for restricting the production of an unwanted
fluid towards the production tubing.
[0036] In one aspect, a wellbore subassembly can include a tube
positioned external to a production tubing. The tube can have an inner wall that
includes a superhydrophobic material for restricting production of an unwanted
fluid toward the production tubing.
[0037] In another aspect, a wellbore subassembly can include a gravel
pack with proppants. The proppants of the gravel back can be positioned
between a production tubing and a wellbore. The proppants can be coated with a
superhydrophobic material for restricting production of an unwanted fluid toward
the production tubing.
[0038] The foregoing description of certain aspects, including illustrated
aspects, has been presented only for the purpose of illustration and description
and is not intended to be exhaustive or to limit the disclosure to the precise forms
disclosed. Numerous modifications, adaptations, and uses thereof will be
apparent to those skilled in the art without departing from the scope of this
disclosure.

What is claimed is:
1. A wellbore subassembly, comprising:
a device having a production flow path toward production tubing, wherein
the production flow path includes a superhydrophobic coating for restricting
production of an unwanted fluid toward the production tubing.
2 . The wellbore subassembly of claim 1, wherein the unwanted fluid has a
greater concentration of at least one of water or natural gas or steam than a
wanted fluid.
3 . The wellbore subassembly of claim 1, wherein the device is a flow control
device comprising a helical production flow path.
4 . The wellbore subassembly of claim 3, wherein the superhydrophobic
coating is overlaid on a surface of the helical production flow path.
5 . The wellbore subassembly of claim 1, wherein the superhydrophobic
coating has a contact angle with a water droplet that exceeds than one hundred
and fifty degrees.
6 . The wellbore subassembly of claim 1, wherein the superhydrophobic
coating includes at least one of manganese oxide polystyrene, zinc oxide
polystyrene, precipitated calcium carbonate, carbon nano-tube structures, and
silica-based nano-coating.
7 . The wellbore subassembly of claim 1, wherein the superhydrophobic
coating is operable for increasing a velocity of fluid having a greater
concentration of oil flowing along the production flow path.
8 . The wellbore subassembly of claim 1, wherein the device includes a
gravel pack having a plurality of proppants, the plurality of proppants having an
outer surface that includes the superhydrophobic coating and wherein the
production flow path is defined by the space between the plurality of proppants.
9 . The wellbore subassembly of claim 1, wherein the device is part of a sand
control screen assembly.
10. A wellbore subassembly, comprising:
a tube positioned external to a production tubing, the tube having an inner
wall that includes a superhydrophobic material for restricting production of an
unwanted fluid toward the production tubing.
11. The wellbore subassembly of claim 10, wherein the tube is positioned
around an outer surface of the production tubing.
12. The wellbore subassembly of claim 10, wherein the unwanted fluid has a
greater concentration of at least one of water or natural gas than a wanted fluid.
13. The wellbore subassembly of claim 12, wherein the superhydrophobic
material is operable for decreasing a velocity of fluid having a greater
concentration of at least one of water or natural gas than the wanted fluid flowing
through the tube.
14. The wellbore subassembly of claim 10, wherein the superhydrophobic
material includes at least one of manganese oxide polystyrene, zinc oxide
polystyrene, precipitated calcium carbonate, carbon nano-tube structures, and
silica-based nano-coating.
15. The wellbore subassembly of claim 10, wherein the superhydrophobic
material is operable for increasing a velocity of fluid having a greater
concentration of oil flowing through the tube.
16. A wellbore subassembly, comprising:
a gravel pack comprising a plurality of proppants positioned between a
production tubing and a wellbore, the plurality of proppants coated with a
superhydrophobic material for restricting production of an unwanted fluid toward
the production tubing.
17. The wellbore subassembly of claim 16, wherein the unwanted fluid has a
greater concentration of at least one of water or natural gas than a wanted fluid.
18. The wellbore subassembly of claim 16, wherein the superhydrophobic
material has a contact angle with a water droplet that exceeds one hundred and
fifty degrees.
19. The wellbore subassembly of claim 16, wherein the superhydrophobic
material includes at least one of manganese oxide polystyrene, zinc oxide
polystyrene, precipitated calcium carbonate, carbon nano-tube structures, and
silica-based nano-coating.
20. The wellbore subassembly of claim 16, wherein the superhydrophobic
material is operable for increasing a velocity of fluid having a greater
concentration of oil flowing through the gravel pack.