U.S. patent application number 12/903529 was filed with the patent office on 2012-04-19 for downhole material-delivery system for subterranean wells.
Invention is credited to Slaheddine Kefi.
Application Number | 20120090835 12/903529 |
Document ID | / |
Family ID | 45933097 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120090835 |
Kind Code |
A1 |
Kefi; Slaheddine |
April 19, 2012 |
DOWNHOLE MATERIAL-DELIVERY SYSTEM FOR SUBTERRANEAN WELLS
Abstract
Methods for releasing tracers into a well for diagnostic studies
during subterranean-well operations comprise filling one or more
hollow bodies with substances The system that comprise a
cementing-plug-launching system, a drill string, casing, coiled
tubing, wireline or combinations thereof. After the system is
lowered into the well, the tracer substance may be remotely and
safely released into the well.
Inventors: |
Kefi; Slaheddine; (Velizy
Villacoublay, FR) |
Family ID: |
45933097 |
Appl. No.: |
12/903529 |
Filed: |
October 13, 2010 |
Current U.S.
Class: |
166/252.6 |
Current CPC
Class: |
E21B 27/02 20130101;
E21B 33/16 20130101; E21B 47/11 20200501 |
Class at
Publication: |
166/252.6 |
International
Class: |
E21B 49/00 20060101
E21B049/00 |
Claims
1. A method for measuring process-fluid loss in a subterranean well
having a wellbore, comprising: i. at a secure location, placing one
or more tracers into at least one body with at least one internal
chamber; ii. incorporating the body into a system comprising one or
more members of the list comprising a cementing-plug-launching
system, a drill string, casing, coiled tubing and a wireline; iii.
lowering the system into the well; iv. releasing one or more
tracers into the well; and v. monitoring the tracer concentrations
in process fluids circulating past the borehole wall.
2. The method of claim 1, wherein one tracer is released above the
loss zone, and a different tracer is released below the loss
zone.
3. The method of claim 2, wherein the tracer concentrations are
monitored in process fluid located above the loss zone.
4. The method of claim 1, wherein one or more tracers are released
above the loss zone.
5. The method of claim 1, wherein one or more tracers are released
below the loss zone.
6. The method of claim 1, wherein the tracer comprises one or more
members of the list comprising: radioactive compounds,
transition-metal compounds, organic compounds and dyes.
7. The method of claim 1, wherein the tracer release is initiated
by process-fluid flow.
8. The method of claim 1, wherein the tracer release is initiated
by means that are independent of process-fluid flow.
9. The method of claim 8, wherein the independent means comprise
one or more members of the list comprising electric motors,
magnetic fields and explosive devices.
10. The method of claim 1, further comprising the release of one or
more microelectric mechanical systems.
11. The method of claim 1, wherein the process fluid is analyzed
after removal from the well.
12. The method of claim 1, wherein the process fluid is analyzed
remotely by sensors in the well.
13. A method for improving wellsite-personnel safety during
subterranean-well operations, comprising: i. at a secure location,
placing a hazardous substance into at least one body with at least
one internal chamber; ii. sealing the body; iii. incorporating the
sealed body into a system comprising one or more members of the
list comprising a cementing-plug-launching system, a drill string,
casing, coiled tubing and a wireline; iv. lowering the system into
the well; and v. releasing the substance into the well.
14. The method of claim 13, wherein the release of the substance
into the well is initiated by process-fluid flow.
15. The method of claim 13, wherein the release of the substance
into the well is initiated by means that are independent of
process-fluid flow.
16. The method of claim 15, wherein the independent means comprise
one or more members of the list comprising electric motors,
magnetic fields and explosive devices.
17. The method of claim 13, wherein the substance comprises fluids,
particles, fibers or combinations thereof.
18. The method of claim 13, wherein the substance comprises one or
more tracers.
19. A method for diagnosing fluid loss in a subterranean well
having a wellbore, comprising: i. placing one or more tracers into
at least one internal chamber of a system comprising one or more
members of the list comprising a cementing-plug-launching system, a
drill string, casing, coiled tubing and a wireline; iii. lowering
the system into the well; iv. releasing one or more tracers into
the well; and v. monitoring the tracer concentrations in process
fluids circulating past the borehole wall.
20. The method of claim 19 wherein the diagnosis is the severity of
the fluid loss zone, or the location of the fluid-loss zone or
both.
Description
BACKGROUND OF THE INVENTION
[0001] The statements in this section merely provide background
information related to the present disclosure and may not
constitute prior art.
[0002] The present invention is related in general to equipment for
servicing subterranean wells. Particularly, the invention relates
to an apparatus and methods for dispensing a material into a
process-fluid stream.
[0003] Well construction, production and workover operations
frequently involve the injection or circulation of process fluids
that perform various functions. Common process fluids include, but
are not limited to, drilling fluids, cement slurries, spacer
fluids, chemical washes, matrix-acidizing fluids,
hydraulic-fracturing fluids, completion fluids,
formation-consolidation fluids and carrier fluids for sand
control.
[0004] Under various circumstances, it is necessary to inject
limited amounts of a material into the well. Such circumstances
include (but are not limited to) injecting tracers to help
operators monitor the status of a well-service operation, and
introducing an activator such as a crosslinker to change the
properties of the process fluid, filter cakes along the formation
wall, or even fluids within the formation. Some of these materials
may be hazardous. For example, they may be radioactive, flammable,
corrosive, explosive or poisonous. Under these circumstances,
devices and methods for isolating the hazardous substances from
wellsite personnel would be desirable.
[0005] The material may be a fluid, a solid or both. In some cases
the solid may be suspended in a fluid. In the case of fluids and
solid suspensions, there are several common placement methods. One
method is to pump a plug of material down the well, using process
fluid as a displacement medium. A disadvantage of this technique is
that the material may become diluted with process fluid during its
journey to the intended well location, or it may react with
components in the wellbore during transit. In addition, if the well
is deep, a large volume of process-fluid may be required to
transport the plug to the intended well location. If, for example,
lost-circulation difficulties are being experienced, pumping large
volumes of process fluid may damage the well.
[0006] Another material-transport method involves lowering a
small-diameter tube (often coiled tubing) into the well, and
pumping the material down the tube to its intended destination. The
use of tubing solves many of the problems associated with pumping
plugs, but the cost and risk of hanging a small-diameter tube into
a wellbore is substantial. Also, the material to be injected may be
corrosive and, as tubing walls tend to be thin compared to
drillpipe or casing, the tube may become damaged.
[0007] Yet another material-transport method involves
encapsulation. Placing a coating around the material, or making the
material the internal phase of an emulsion, may provide protection
as the material travels to its destination downhole. Methods for
releasing the material may include time, temperature, shear, pH
change and irradiation. However, these release mechanisms are not
always reliable. If a wellbore operation is delayed, the material
may be release prematurely. Also, the temperature at the intended
destination may not be accurately known, and may change with time.
The intended location may not be at the bottom of the well. Under
these circumstances, shearing at a drill bit would not be the
optimal solution. Chemical triggers and equipment for irradiation
may not be available at the well site.
[0008] Thus, despite the valuable contributions of the prior art,
there is a need for improved techniques by which a material may be
safely delivered to an intended downhole location without having to
contend with the problems and uncertainties described above.
SUMMARY OF THE INVENTION
[0009] The present invention provides the aforementioned need.
[0010] Embodiments relate to methods for measuring process-fluid
loss in a subterranean well.
[0011] Further embodiments relate to the launching of tracers
downhole in order to diagnose the location and/or severity of loss
zones.
[0012] Even further embodiments pertain to improving wellsite
safety when using hazardous substances to be launched downhole.
[0013] All aspects of the invention may be applied in oil and gas
wells, geothermal wells, water wells, and wells for chemical waste
disposal, enhanced recovery of hydrocarbons and carbon
sequestration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 illustrates one example of the method by which a
material may be launched into a process-fluid stream.
[0015] FIG. 2 presents an alternate view of the example shown in
FIG. 1.
DETAILED DESCRIPTION
[0016] During primary cementing it is usually desirable to minimize
commingling between the various process fluids that travel through
the casing--for example, drilling fluid and cement slurry. One way
to minimize commingling involves using wiper plugs to separate
fluids as they travel down the casing. Wiper plugs also clean the
inner surface of the casing. Most cementing operations involve two
wiper plugs: a bottom plug that separates cement slurry from
drilling fluid, and a bottom plug that separates cement slurry from
displacement fluid.
[0017] After the casing is installed in the wellbore, the annulus
between the casing and the wellbore wall (or another casing string)
is usually filled with drilling fluid. When primary cementing
begins, the bottom plug is first launched into the casing, followed
by the cement slurry. The cement slurry may be preceded by a spacer
fluid, a chemical wash or both. The function of the bottom plug is
to scrape traces of drilling fluid from the internal surface of the
casing, and to prevent contact between the drilling fluid and the
cement slurry.
[0018] The bottom-plug launching and conveyance through the casing
arises from pressure applied by the cement slurry. When the bottom
plug completes its journey through the casing, it becomes seated on
float equipment installed at the bottom of the casing. Continued
pumping exerts sufficient pressure to rupture a membrane at the top
of the bottom plug, allowing the cement slurry to flow through an
interior passage in the bottom plug, exit the bottom of the casing
and continue into the annulus.
[0019] After sufficient cement slurry to fill the annulus has been
pumped into the casing, the top plug is launched into the casing,
and a displacement fluid is pumped behind the plug. The
displacement fluid forces the plug through the casing. The function
of the top plug is to scrape traces of cement slurry from the
internal surface of the casing, isolate the cement slurry from the
displacement fluid and, upon landing on the bottom plug, seal the
casing interior from the annulus. Unlike the bottom plug, the top
plug has no membrane or interior passage through which fluids may
flow.
[0020] A thorough description of the primary cementing process and
the equipment employed to perform the service may be found in the
following references. (1) Piot B. and Cuvillier G.: "Primary
Cementing," in Nelson E. B. and Guillot D. (eds.): Well
Cementing-2.sup.nd Edition, Houston: Schlumberger (2006): 459-501.
(2) Leugemors E., Metson J., Pessin J.-L., Colvard R. L., Krauss C.
D. and Plante M.: "Cementing Equipment and Casing Hardware," in
Nelson E. B. and Guillot D. (eds.): Well Cementing-2.sup.nd
Edition, Houston: Schlumberger (2006): 343-434.
[0021] Wiper plugs are usually launched from a cementing head that
is attached to the casing near the drilling rig. The casing rises
from the bottom of the open hole to the rig floor. However, for
subsea completions, the problem becomes more complicated, and fluid
isolation becomes more and more critical as water depth increases.
It thus becomes impractical to launch wiper plugs from the surface.
Therefore, the cementing head containing the wiper plugs rests on
the seafloor, and the top of the casing ends at the mudline.
Drillpipe connects the top of the casing to the rig floor on the
surface. During the cementing process, darts are released into the
drillpipe on surface, travel through the drillpipe to the seafloor
and, upon arrival, trigger the release of the wiper plugs.
[0022] After the first dart is launched, cement slurry is pumped
behind it. When the first dart lands inside the cementing head, the
bottom plug is released. The second dart is launched after
sufficient cement slurry has been pumped to fill the annulus. A
displacement fluid is pumped behind the second dart. When the
second dart arrives, the top plug is released. A brief peak in
surface pressure indicates when each wiper plug has been launched.
This process is detailed in the following references: (1) Buisine
P. and Lavaure G.: "Equipment for Remote Launching of Cementing
Plugs into Subsea Drilled Wells," European Patent Application 0 450
676 A1 (1991); (2) Brandt W. et al.: "Deepening the Search for
Offshore Hydrocarbons." Oilfield Review (Spring 1998) 10, No.
1,2-21.
[0023] The present example of the method is designed to be
compatible with the aforementioned plug-launching sequence but
shall not be limited to it. The apparatus, shown in FIG. 1A,
comprises a system for launching cementing plugs in a subterranean
well, wherein at least one a bottom plug 101 and a top plug 102 are
launched from a plug basket 103. The first portion of the apparatus
comprises a plug basket 103 that initially contains the bottom plug
101 and the top plug 102. A plug piston 104 is driven by a main rod
105, equipped with a main rod head 106. Above the main rod head 106
is at least one hollow body 107 that may contain one or more
substances. The body is equipped with injectors 108. The injectors
have check valves to prevent the influx of wellbore fluids into the
interior of the hollow body 107. A piston 109 is fitted inside the
hollow body, and is connected to a dart rod 110. A dart-rod head
111 is fitted on top of the dart rod. The dart rod and dart-rod
head are enclosed inside a first tubular body 112. Flow ports 113
and 114 in the first tubular body allow process fluids to flow
outside of the apparatus.
[0024] The second portion of the apparatus comprises a
material-injection dart 115. The third portion of the apparatus
comprises a bottom dart 116. The fourth portion of the apparatus
comprises a top dart (not shown).
[0025] After assembly, the apparatus is installed inside a casing
string (not shown) (FIG. 1, Step A). Outside of the casing string
is an annular region (not shown). The other side of the annular
region may comprise the borehole wall or another casing string. A
first process fluid flows through the first tubular body 112 and
out through ports 113 and 114 into the annulus between the first
tubular body and the casing interior. Process fluid bypasses the
plug-launching system, and then flows toward the float collar (not
shown) at the end of the casing string.
[0026] Step B depicts the arrival of a fluid-injection dart 115,
landing on dart-rod head 116, installed on the dart rod 110. The
dart obstructs fluid flow through ports 113 and 114. Further
pumping of process fluid forces the fluid-injection dart downward,
thereby forcing the dart rod 110 downward, thereby causing the
reservoir piston 109 to move downward and force the material
through the additive injectors 108, and outside of the
apparatus.
[0027] Step C shows that, once the fluid-injection dart has cleared
flow ports 113 and 114, the reservoir piston 109 has moved
sufficiently far to expel all of the substance from the hollow body
107. At this point, the main rod 106, the top plug 102 and the
bottom plug 101 have not been affected. However, the dart rod and
the main rod are touching.
[0028] Step D shows the aftermath of the bottom-dart 116 arrival
and displacement. As the bottom dart traveled into the apparatus,
shear pins connecting the dart rod 110 and the reservoir piston 109
broke, thereby allowing the dart rod to continue moving downward.
Continued downward movement of the dart rod forced the main rod 105
to also move downward, forcing the piston 104 to move downward and
launch the bottom dart.
[0029] The cementing process may then continue in the manner well
known in the art, whereby the bottom plug and top plug are
launched. An alternate view of the sequence is shown in FIG. 2.
[0030] Embodiments relate to methods for measuring process-fluid
loss in a subterranean well. Process-fluid loss may include lost
circulation (loss of whole process fluid to the formation) or
fluid-loss (loss of the fluid phase of the process fluid, leaving
suspended solids in the wellbore). This embodiment involves
selectively releasing one or more tracers into the process fluid at
desired locations in the vicinity of the loss zones. This technique
is advantageous because it isolates the tracers from wellsite
personnel, and allows more accurate diagnostic studies.
[0031] In this embodiment, the apparatus may comprise one or more
hollow bodies, each containing the same tracer or different
tracers. Or, one body may comprise multiple internal chambers
containing the same tracer or different tracers. The hollow bodies
are preferably filled with tracer at a secure location. Later they
may be incorporated into a system that may comprise one or more
members of the list comprising a cementing-plug-launching system, a
drill string, casing, coiled tubing and a wireline. The system may
then be lowered into the well. The internal chamber may also be
filled extemporaneously by the well site personnel when needed.
[0032] During the circulation of process fluid in the wellbore, the
first tracer may be injected at a location above the loss zone, and
the second tracer may be injected at a location below the loss
zone. As the process fluid circulates to surface, the relative
concentrations of the two tracers in the process fluid may be
monitored at a location above the loss zone. The concentration
measurements would allow one to calculate the rate at which process
fluid is being lost to the formation. Lower relative second-tracer
concentrations would likely indicate more severe process-fluid-loss
situations. The tracers may be released in bursts or
continuously.
[0033] Another strategy comprises releasing one or more tracers
into the process-fluid above the loss zone. Monitoring the tracer
concentration in process fluid at a point above the location where
the tracer was released may allow one to establish a baseline value
in the process fluid. Next, one or more tracers may be released
into the process fluid below the loss zone. Monitoring the tracer
concentration at the same point above the loss zone may allow one
to calculate the rate at which process fluid is being lost to the
formation. Again, the lower the tracer concentration, the more
severe the loss situation may be.
[0034] Skilled persons in the art will recognize that the present
invention is not limited to the aforementioned tracer-release
scenarios.
[0035] The tracer-concentration measurements may be performed with
process-fluid samples that have been removed from the well.
Alternatively, downhole sensors may be employed to perform the
measurements remotely.
[0036] The tracers may comprise (but would not be limited to)
radioactive compounds, transition-metal compounds, organic
compounds, dyes or combinations thereof. The chamber may also be a
vehicle by which microelectric mechanical systems (MEMS) are
introduced into the wellbore. In this instance, the MEMS may be
employed as tracers.
[0037] There are several methods by which release of the tracer may
be initiated downhole. Release may be initiated directly or
indirectly by process-fluid flow. Or, release may be initiated by
means that are independent of process-fluid flow. Such means may
include (but would not be limited to) electric motors, magnetic
fields and explosive devices. One of the major advantages of the
present embodiments is that the tracer is launched directly down
the well, accordingly, it just has to travel up the annulus to be
measured on surface. In the prior art, the tracer is usually
incorporated to process fluid on surface or pumped as a pill
between two fluids. The problem is that the tracer or the fluid
containing the tracer has to travel down the casing, pass the
wellhead and then come up the annulus to surface. Reducing the time
the tracer spends within the process fluid and the journey it has
to go through limits the losses and the parameters to take into
account while assessing the diagnostic.
[0038] Embodiments provide methods for improving wellsite-personnel
safety during subterranean-well operations.
[0039] Indeed, as mentioned earlier, the methods may involve the
launching of tracers such as radioactive tracers; furthermore one
may envisage storing further hazardous substances into at least one
body with at least one internal chamber. The body is preferably
filled with the hazardous substance at a secure location away from
wellsite personnel. Such locations may include (but would not be
limited to) remote facilities away from the wellsite and isolated
areas in the vicinity of the wellsite. After filling, the body is
sealed and incorporated into a system from which the hazardous
substance will be dispensed downhole. Such systems may comprise one
or more members of the list comprising a cementing-plug-launching
system, a drill string, casing, coiled tubing and a wireline. The
system containing the sealed body is then lowered into the well,
and the hazardous substance is released from the sealed body at one
or more desired locations.
[0040] There are several methods by which release of the hazardous
material may be initiated downhole. Release may be initiated
directly or indirectly by process-fluid flow. Or, release may be
initiated by means that are independent of process-fluid flow. Such
means may include (but would not be limited to) electric motors,
magnetic fields and explosive devices.
[0041] The hazardous material may be in the form of a fluid,
particles, fibers or combinations thereof. Envisioned hazardous
materials include (but would not be limited to) radioactive,
flammable, explosive, corrosive and poisonous materials, or
combinations thereof.
[0042] The material may be as said earlier a tracer for diagnostic
studies. Such tracers may be (but would not be limited to) one or
more members of the list comprising radioactive compounds,
transition-metal compounds, organic compounds and dyes.
[0043] Fibers may be dispensed by the apparatus of the invention
for applications including (but not limited to) curing lost
circulation, improving fluid-loss control and as diverting agents.
Having fibers dispensed in a controlled manner, close to the
formation being treated, may be advantageous.
[0044] The material may further comprise one or more microelectric
mechanical systems (MEMS). MEMS are mechanical devices that are
built onto semiconductor chips, whose sizes are measured in
micrometers. The MEMS may be suspended in a fluid inside the body.
When dispensed into the well, MEMS may perform, for example,
pressure, temperature, chemical, optical and vibration
measurements, record data and transmit information to the surface.
In the context of the invention, strategic release of MEMS at a
desired location may provide valuable information concerning the
well-service operation. The MEMS may be recovered at the surface
for data recovery during process-fluid circulation, or they may be
monitored remotely while they are circulating in the well.
[0045] An example of the method comprises incorporating the body
within a cementing-plug-launching system. The launching system of
this particular embodiment is designed to operate in a subsea
environment--one in which it may be particularly advantageous to
have the ability to remotely dispense a material into the wellbore.
This example relies on process-fluid flow to initiate material
release.
[0046] The preceding description has been presented with reference
to presently preferred embodiments of the invention. Persons
skilled in the art and technology to which this invention pertains
will appreciate that alterations and changes in the described
structures and methods of operation can be practiced without
meaningfully departing from the principle, and scope of this
invention. Accordingly, the foregoing description should not be
read as pertaining only to the precise structures described and
shown in the accompanying drawings, but rather should be read as
consistent with and as support for the following claims, which are
to have their fullest and fairest scope.
* * * * *