U.S. patent application number 14/054106 was filed with the patent office on 2014-04-17 for mitigating thief zone losses by thief zone pressure maintenance through downhole radio frequency radiation heating.
This patent application is currently assigned to CONOCOPHILLIPS COMPANY. The applicant listed for this patent is CONOCOPHILLIPS COMPANY. Invention is credited to Chris LEHECKA, Daniel R. SULTENFUSS.
Application Number | 20140102700 14/054106 |
Document ID | / |
Family ID | 50474333 |
Filed Date | 2014-04-17 |
United States Patent
Application |
20140102700 |
Kind Code |
A1 |
SULTENFUSS; Daniel R. ; et
al. |
April 17, 2014 |
MITIGATING THIEF ZONE LOSSES BY THIEF ZONE PRESSURE MAINTENANCE
THROUGH DOWNHOLE RADIO FREQUENCY RADIATION HEATING
Abstract
Methods are provided for mitigating thief zone losses during
hydrocarbon recovery by thief zone pressure maintenance through
downhole radio frequency (RF) radiation heating. A thief zone
situated near a hydrocarbon reservoir poses a risk of losing
valuable components from the reservoir to the thief zone. In
addition to the risk of loss of diluent, heat, or steam to the
thief zone, valuable hydrocarbons may also be lost to the thief
zone. One way to mitigate these losses is by maintaining thief zone
pressure. RF radiation may be used to heat a thief zone fluid to
maintain pressure in the thief zone, decreasing the driving force
for losses to the thief zone. In some cases, steam generated thusly
may be used to enhance hydrocarbon thermal recovery. Advantages of
methods herein include: lower costs, higher efficiencies, higher
hydrocarbon recovery, less hydrocarbon contamination, increased
hydrocarbon mobility, and fewer thief zone losses.
Inventors: |
SULTENFUSS; Daniel R.;
(Calgary, CA) ; LEHECKA; Chris; (Katy,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONOCOPHILLIPS COMPANY |
Houston |
TX |
US |
|
|
Assignee: |
CONOCOPHILLIPS COMPANY
Houston
TX
|
Family ID: |
50474333 |
Appl. No.: |
14/054106 |
Filed: |
October 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61714315 |
Oct 16, 2012 |
|
|
|
Current U.S.
Class: |
166/272.1 ;
166/272.3 |
Current CPC
Class: |
E21B 43/2401 20130101;
E21B 43/2408 20130101 |
Class at
Publication: |
166/272.1 ;
166/272.3 |
International
Class: |
E21B 43/24 20060101
E21B043/24 |
Claims
1. A method for mitigating thief zone losses during heavy oil
recovery by thief zone pressure maintenance through downhole radio
frequency radiation heating comprising the steps of: introducing a
steam assisted gravity drainage (SAGD) well pair into a
subterranean formation, wherein the SAGD well pair comprises a
producing well and a steam injection well, wherein subterranean
formation comprises a hydrocarbon reservoir wherein the hydrocarbon
reservoir comprises hydrocarbons; introducing steam into the steam
injection well to establish a steam chamber in the hydrocarbon
reservoir; introducing an antenna into the subterranean formation,
wherein the antenna is operable connected to an energy source,
wherein the subterranean formation comprises a thief zone, wherein
the thief zone is in thermal communication, fluid communication, or
both with the steam chamber, wherein the thief zone comprises
water; inducing radio frequency radiation in the antenna by way of
the energy source; allowing the radio frequency radiation to
propagate into the thief zone to heat at least a portion of the
water therein to form steam to increase the pressure in the thief
zone from a first thief zone pressure to a second thief zone
pressure, wherein the second thief zone pressure mitigates or
eliminates hydrocarbon or heat losses to the thief zone that would
otherwise occur if the thief zone had remained at the first thief
zone pressure; and producing the hydrocarbons from the hydrocarbon
reservoir through the producing well.
2. The method of claim 1 wherein the step of inducing radio
frequency radiation in the antenna generates radio frequency
radiation at a frequency from about 30 kHz to about 300 GHz.
3. The method of claim 1 wherein the hydrocarbons are bitumen.
4. The method of claim 1 wherein the thief zone is situated in an
overburden of the hydrocarbon reservoir.
5. The method of claim 1 wherein the thief zone is situated in the
hydrocarbon reservoir.
6. The method of claim 1 wherein the thief zone is a depleted steam
chamber in the hydrocarbon reservoir.
7. The method of claim 1 wherein the antenna is situated above the
hydrocarbon reservoir and wherein the antenna intersects the thief
zone.
8. A method for mitigating thief zone losses by thief zone pressure
maintenance through downhole radio frequency radiation heating
comprising the steps of: introducing an antenna into a subterranean
formation, wherein the antenna is operable connected to an energy
source, wherein the subterranean formation comprises a hydrocarbon
reservoir and a thief zone, wherein the thief zone is in thermal
communication, fluid communication, or both with the hydrocarbon
reservoir, wherein the hydrocarbon reservoir comprises
hydrocarbons, and wherein the thief zone comprises a thief zone
fluid susceptible to heating from radio frequency radiation;
inducing radio frequency radiation in the antenna by way of the
energy source; allowing the radio frequency radiation to propagate
into the thief zone to heat at least a portion of the thief zone
fluid therein to vaporize the thief zone fluid to form a thief zone
gas to increase the pressure in the thief zone from a first thief
zone pressure to a second thief zone pressure, wherein the second
thief zone pressure mitigates fluid or heat interaction between the
thief zone and the hydrocarbon reservoir that would otherwise occur
if the thief zone had remained at the first thief zone pressure;
and producing the hydrocarbons from the hydrocarbon reservoir.
9. The method of claim 8 wherein the step of producing the
hydrocarbons comprises the step of recovering the hydrocarbons by
way of a thermal recovery process.
10. The method of claim 9 wherein the thermal recovery process is a
steam assisted gravity drainage (SAGD) process, a cyclic steam
stimulation, a vapor extraction, a J-well SAGD, in situ combustion,
a high pressure air injection, an expanding solvent-SAGD, a
cross-SAGD process, or a combination thereof.
11. The method of claim 9 wherein the thief zone fluid comprises
water and wherein the thief zone gas comprises steam.
12. The method of claim 11 further comprising the step of:
determining an optimum excitation frequency of the radio frequency
radiation by determining which frequency of the radio frequency
radiation optimizes the thermal recovery process based on a depth
of radio frequency penetration, a heat absorption of the radio
frequency radiation, and an overall heat input by the radio
frequency radiation at a given frequency; wherein the step of
inducing radio frequency radiation in the antenna generates radio
frequency radiation at the optimal excitation frequency.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a non-provisional application which
claims benefit under 35 USC .sctn.119(e) to U.S. Provisional
Application Ser. No. 61/714,315 filed Oct. 16, 2012, entitled "
Mitigating Thief Zone Losses by Pressure Maintenance through
Downhole Radio Frequency Radiation Heating," which is incorporated
herein in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] None.
FIELD OF THE INVENTION
[0003] The present invention relates generally to methods and
systems for mitigating thief zone losses during heavy oil recovery
by thief zone pressure maintenance through downhole radio frequency
radiation heating.
BACKGROUND
[0004] The production of hydrocarbons from low mobility reservoirs
presents significant challenges. Low mobility reservoirs are
characterized by high viscosity hydrocarbons, low permeability
formations, and/or low driving forces. Any of these factors can
considerably complicate hydrocarbon recovery. Extraction of high
viscosity hydrocarbons is typically difficult due to the relative
immobility of the high viscosity hydrocarbons. For example, some
heavy crude oils, such as bitumen, are highly viscous and therefore
immobile at the initial viscosity of the oil at reservoir
temperature and pressure. Many countries in the world have large
deposits of bitumen oil sands, including the United States, Russia,
and various countries in the Middle East. The world's largest
deposits, however, occur in Canada and Venezuela. Oil sands are a
type of unconventional petroleum deposit. The sands contain
naturally occurring mixtures of sand, clay, water, and a dense and
extremely viscous form of petroleum technically referred to as
"bitumen," but may also be called heavy oil or tar. Indeed, such
heavy oils may be quite thick and have a consistency similar to
that of peanut butter or heavy tars, making their extraction from
reservoirs especially challenging. Due to its high viscosity, these
heavy oils are hard to mobilize, and they generally must be made to
flow to produce and transport them. Indeed, such heavy oils are
typically so heavy and viscous that they will not flow unless
heated or diluted with lighter hydrocarbons. At room temperature,
it is much like cold molasses.
[0005] As used herein, the term, "heavy oil" includes any heavy
hydrocarbons having greater than 10 carbon atoms per molecule.
Further, the term "heavy oil" includes heavy hydrocarbons having a
viscosity in the range of from about 100 to about 100,000
centipoise at 100.degree. F., and an API gravity from about 5 to
about 22.degree. API; or can be a bitumen having a viscosity less
than about 100,000 centipoise, and an API gravity less than or
equal to about 22.degree. API.
[0006] Conventional approaches to recovering heavy oils often focus
on methods for lowering the viscosity of the heavy oil or heavy oil
mixture so that the heavy oil may be mobilized and produced from
the reservoir. Examples of methods for lowering the heavy oil
viscosity include introducing a diluent to the heavy oil or heating
the heavy oil. Commonly used thermal recovery methods include a
number of technologies, such as steam flooding, cyclic steam
stimulation, and steam assisted gravity drainage (SAGD), which
require the injection of hot fluids into the reservoir. A
100.degree. F. increase in the temperature of the heavy oil in a
formation can lower its viscosity by two orders of magnitude.
Accordingly, heating a formation containing heavy oils can
dramatically improve the efficiency of heavy oil recovery.
[0007] While these diluent and thermal recovery methods are often
effective at recovering heavy oils, these methods may fail to be
economical under certain conditions. For instance, some hydrocarbon
reservoirs may be in thermal or fluid communication with a thief
zone. Thief zones are gas or water pools to which steam, diluent,
heat, or hydrocarbons may escape. In the example of SAGD-assisted
hydrocarbon recovery, a well pair is used to develop a steam
chamber in the hydrocarbon reservoir that interacts with and acts
to produce the heavy oil around the steam chamber. If the SAGD
steam chamber happens to establish thermal or fluid communication
with a neighboring thief zone in the vicinity thereof, steam,
hydrocarbons, or heat will be lost to the thief zone or conversely,
the thief zone gas/liquids could invade the SAGD steam chamber. The
amount of steam lost to a neighboring thief zone can render thermal
recovery processes uneconomical.
[0008] Where diluent-assisted recovery methods are employed, thief
zones can similarly rob the producing zone of valuable diluent or
otherwise contaminate the diluent as the case may be. Because
solvent is typically quite expensive, the process economics of
using diluents are highly sensitive to solvent losses. Thus, as is
the case for thermal recovery processes, neighboring thief zones
can also render diluent-assisted recovery methods uneconomical as
well.
[0009] Conventional methods for mitigating losses to thief zones
rely on the injection of non-condensable gases into the thief zone.
In these conventional methods, the non-condensable gas is injected
into the thief zone with the hope of maintaining or increasing the
pressure in the thief zone to minimize or eliminate losses to the
thief zone. These conventional methods however remain fairly new
and accordingly, operators have not accumulated much experience
with these methods. Thus, the predictability of these conventional
methods remain fairly unpredictable. Another disadvantage of these
conventional methods is the risk of contaminating the hydrocarbon
reservoir with the injected non-condensable gases.
[0010] Still another disadvantage of conventional methods is the
contamination that results to the thief zone itself. In some cases,
the thief zone may be another hydrocarbon-bearing reservoir (in
some cases owned by a different operator). Injecting
non-condensable gases into another's hydrocarbon-bearing reservoir
will result in contamination of the thief zone hydrocarbons. Where
these hydrocarbons are owned by another operator, liability for the
devaluation of those thief zone hydrocarbons will be borne by the
contaminator of the thief zone. Accordingly, avoiding thief zone
contamination in such instances is highly economically desirable to
avoid incurring such liability to other operators.
[0011] Accordingly, enhanced methods for mitigating or reducing
thief zone interactions are needed that address one or more
disadvantages of the prior art, especially as relating to thermal
and diluent-assisted hydrocarbon recovery techniques.
SUMMARY
[0012] The present invention relates generally to methods and
systems for mitigating thief zone losses during heavy oil recovery
by thief zone pressure maintenance through downhole radio frequency
radiation heating.
[0013] One example of a method for mitigating thief zone losses
during heavy oil recovery by thief zone pressure maintenance
through downhole radio frequency radiation heating comprises the
steps of: introducing a steam assisted gravity drainage (SAGD) well
pair into a subterranean formation, wherein the SAGD well pair
comprises a producing well and a steam injection well, wherein
subterranean formation comprises a hydrocarbon reservoir wherein
the hydrocarbon reservoir comprises hydrocarbons; introducing steam
into the steam injection well to establish a steam chamber in the
hydrocarbon reservoir; introducing an antenna into the subterranean
formation, wherein the antenna is operable connected to an energy
source, wherein the subterranean formation comprises a thief zone,
wherein the thief zone is in thermal communication, fluid
communication, or both with the steam chamber, wherein the thief
zone comprises water; inducing radio frequency radiation in the
antenna by way of the energy source; allowing the radio frequency
radiation to propagate into the thief zone to heat at least a
portion of the water therein to form steam to increase the pressure
in the thief zone from a first thief zone pressure to a second
thief zone pressure, wherein the second thief zone pressure
mitigates or eliminates hydrocarbon or heat losses to the thief
zone that would otherwise occur if the thief zone had remained at
the first thief zone pressure; and producing the hydrocarbons from
the hydrocarbon reservoir through the producing well.
[0014] One example of a method for mitigating thief zone losses by
thief zone pressure maintenance through downhole radio frequency
radiation heating comprises the steps of: introducing an antenna
into a subterranean formation, wherein the antenna is operable
connected to an energy source, wherein the subterranean formation
comprises a hydrocarbon reservoir and a thief zone, wherein the
thief zone is in thermal communication, fluid communication, or
both with the hydrocarbon reservoir, wherein the hydrocarbon
reservoir comprises hydrocarbons, and wherein the thief zone
comprises a thief zone fluid susceptible to heating from radio
frequency radiation; inducing radio frequency radiation in the
antenna by way of the energy source; allowing the radio frequency
radiation to propagate into the thief zone to heat at least a
portion of the thief zone fluid therein to vaporize the thief zone
fluid to form a thief zone gas to increase the pressure in the
thief zone from a first thief zone pressure to a second thief zone
pressure, wherein the second thief zone pressure mitigates fluid or
heat interaction between the thief zone and the hydrocarbon
reservoir that would otherwise occur if the thief zone had remained
at the first thief zone pressure; and producing the hydrocarbons
from the hydrocarbon reservoir.
[0015] The features and advantages of the present invention will be
apparent to those skilled in the art. While numerous changes may be
made by those skilled in the art, such changes are within the
spirit of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more complete understanding of the present disclosure and
advantages thereof may be acquired by referring to the following
description taken in conjunction with the accompanying figures,
wherein:
[0017] FIG. 1 illustrates an example of a system using a radio
frequency radiation to mitigate thief zone losses in accordance
with one embodiment of the present invention.
[0018] While the present invention is susceptible to various
modifications and alternative forms, specific exemplary embodiments
thereof have been shown by way of example in the drawings and are
herein described in detail. It should be understood, however, that
the description herein of specific embodiments is not intended to
limit the invention to the particular forms disclosed, but on the
contrary, the intention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the appended claims.
DETAILED DESCRIPTION
[0019] The present invention relates generally to methods and
systems for mitigating thief zone losses during heavy oil recovery
by thief zone pressure maintenance through downhole radio frequency
radiation heating.
[0020] In certain embodiments, methods and systems are provided for
mitigating losses to thief zones using radio frequency radiation.
In one embodiment, a thief zone may be situated in a hydrocarbon
reservoir or in proximity to the hydrocarbon reservoir in a way
that poses a risk of losing valuable components from the
hydrocarbon reservoir to the thief zone during hydrocarbon recovery
efforts. Thief zones include any zone that allows loss of valuable
components from the hydrocarbon recovery process including produced
oil, diluent, solvent, treatments, heat, water, steam, pressure,
and the like. Thief zones include areas of the reservoir that
cannot be produced or that reduce productivity of the reservoir
including lean zones, bottom water and the like. Examples of
hydrocarbon recovery processes that may be employed are
diluent-assisted recovery processes or thermal recovery processes
such as the SAGD process. Not only does the presence of the thief
zone pose a risk of loss of either diluent, heat, or steam to the
thief zone, but valuable hydrocarbons can be lost to the thief zone
as well.
[0021] One way to mitigate or eliminate these losses to the thief
zone is by maintaining or increasing the thief zone pressure to
alter the driving forces that motivate losses to the thief zone.
Radio frequency radiation may be used to heat a fluid in the thief
zone, such as water for example. By vaporizing the water to steam,
pressure is maintained in the thief zone decreasing the driving
force for losses to the thief zone. In some cases, the steam
generated in the thief zone may be used to further enhance thermal
recovery of the hydrocarbons.
[0022] Advantages of the enhanced methods and systems described
herein include one or more of the following advantages: lower cost,
higher efficiencies, higher recovery of reservoir hydrocarbons,
less hydrocarbon contamination, and fewer losses to the thief zone
(e.g. heat, steam, hydrocarbons, or diluent). Additionally, the
methods herein may also have the positive effect of introducing
heat to the heavy oils to reduce their viscosity and increase their
mobility, making them easier to recover. Other features,
embodiments, and advantages will be apparent from the disclosure
herein.
[0023] Reference will now be made in detail to embodiments of the
invention, one or more examples of which are illustrated in the
accompanying drawings. Each example is provided by way of
explanation of the invention, not as a limitation of the invention.
It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the scope or spirit of the invention. For
instance, features illustrated or described as part of one
embodiment can be used on another embodiment to yield a still
further embodiment. Thus, it is intended that the present invention
cover such modifications and variations that come within the scope
of the invention.
[0024] FIG. 1 illustrates an example of a system using a radio
frequency radiation to mitigate thief zone losses in accordance
with one embodiment of the present invention. In this example,
hydrocarbon recovery process 120 intersects subterranean formation
105 for producing hydrocarbons from hydrocarbon reservoir 107.
Here, for illustrative purposes hydrocarbon recovery process 120 is
depicted as a thermal recovery process, in this case, a SAGD well
pair comprising production well 121 and steam injection well 122.
Other thermal recovery processes that may be used with the methods
described herein include, but are not limited to, a cyclic steam
stimulation, a vapor extraction, a J-well SAGD, in situ combustion,
a high pressure air injection, an expanding solvent-SAGD, a
cross-SAGD process, or a combination thereof.
[0025] Where a SAGD thermal recovery process is employed, steam is
typically introduced by way of upper steam injection well 122 to
mobilize heavy oil in hydrocarbon reservoir for production through
production wellbore 121. Over time, the circulation of steam and
condensing fluids establishes steam chamber 124 about hydrocarbon
recovery process 120 in hydrocarbon reservoir 107.
[0026] As might be expected, expanding steam chamber 124 may come
into heat or fluid communication with first thief zone 111. Thief
zone 111 poses a risk of losses from hydrocarbon reservoir 107 to
thief zone 111. For example, heat may propagate through conduction
and/or convection from hydrocarbon reservoir 107 to thief zone 111.
Thief zone 111 comprises a thief zone fluid, in this case, water,
which can act as a significant heat sink into which sizable heat
losses may transfer. In addition to heat losses, hydrocarbons
and/or steam may also be lost to thief zone 111. Where hydrocarbon
recovery process 120 is a diluent-assisted recovery process, thief
zone 111 can rob the hydrocarbon reservoir of valuable diluent or
solvent as well.
[0027] Energy generator 162 is operably connected to antenna 164
for generating radio frequency radiation directed to thief zone
111. The thief zone fluid, in this case water, is heated through
interaction with the radio frequency radiation and is vaporized to
a thief zone gas, in this case steam. The steam thus produced
maintains or increases the pressure in thief zone 111 so as to
reduce any driving force that might motivate fluids to escape to
thief zone 111. Additionally, heating thief zone 111 reduces any
thermal driving force that would otherwise motivate heat transfer
from hydrocarbon reservoir 107 to thief zone 111. In this way,
losses to thief zone 111 are thus mitigated.
[0028] Likewise, thief zone 112 poses a similar risk of losses to
hydrocarbon reservoir 107. Unlike thief zone 111, which is situated
in the overburden, thief zone 112 is situated in hydrocarbon
reservoir 107 itself In this example, thief zone 112 is a depleted
steam chamber remaining from an earlier SAGD thermal recovery
process in hydrocarbon reservoir 107.
[0029] Antenna 164 may be situated in any configuration suitable
for directing radio frequency radiation to thief zones 111 or 112.
In certain embodiments, antenna 164 will follow all or a portion of
injection well 160. Antenna 164 may be oriented along a horizontal
length, a vertical length, or both in relation to one or more thief
zones. In FIG. 1, antenna 164 follows an initially vertically
orientation and then, multiple horizontal branches or orientations
along thief zone 111 and thief zone 112. In certain embodiments,
antenna 164 may be situated above hydrocarbon reservoir 107 in the
overburden in or adjacent to thief zone 111.
[0030] In certain embodiments, the frequency of the generated radio
frequency radiation is from about 30 kHz to about 300 GHz. Indeed,
any suitable frequency for interacting with the fluids contained in
the thief zone may be used with the instant invention.
[0031] It is recognized that although the methods described herein
are with reference to water as the thief zone fluid, the thief zone
fluid may be any fluid capable of interacting with and susceptible
to heating by the generated radio frequency radiation.
[0032] The methods contemplated herein may further comprise the
step of determining an optimal frequency or range of frequencies of
the generated radio frequency radiation for heating the reservoir
hydrocarbons. In this way, an optimal radiation frequency may be
determined that maximizes energy transfer to the hydrocarbons for a
given energy input.
[0033] Although the examples depict one injection well and one
production well, it is understood that the methods described herein
could be applied to any number of injection and/or production
wells, including typical circular drive patterns such as the
five-spot, seven-spot, and nine-spot patterns. In certain
embodiments, it may be desired to a single well for both injection
(e.g. air injection and introduction of radio frequency radiation)
and hydrocarbon production. Further, it is recognized that the term
"mixture" as used herein also refers to non-homogeneous
mixtures.
[0034] Although these examples depict any thief zone, they are
applicable to a lean zone or bottom water. Lean zones are thin
zones with high water saturation within the targeted hydrocarbon
formation that can act as thief zone during production. Bottom
water is a highly water saturated zone below the targeted
hydrocarbon zone. Pressure, steam, heat, produced oil or
combinations thereof may be lost to a lean zone or bottom water.
Loss may be prevented in a lean zone or bottom water by inserting
an antenna in the lean zone or bottom water to heat the water, when
the water is sufficiently heated it will increase pressure and/or
generate steam. In one example a lean zone is identified during
production of heavy oil from a SAGD well, an antenna is placed
within the lean zone, the water is heated above boiling point to
release steam until the pressure in the lean zone is raised
sufficiently to prevent loss of steam, heat, or produced oil into
the lean zone. In another embodiment, an antenna is placed below a
SAGD reservoir in a bottom zone, during production if the pressure
is reduced, the bottom water is heated using the antenna. Once the
water is sufficiently heated the pressure in the bottom water will
increase and prevent loss of heat, steam or produced oil into the
bottom water.
[0035] It is recognized that any of the elements and features of
each of the devices described herein are capable of use with any of
the other devices described herein without limitation. Furthermore,
it is recognized that the steps of the methods herein may be
performed in any order except unless explicitly stated otherwise or
inherently required otherwise by the particular method.
[0036] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as the present invention may be modified and
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in the
claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered or modified
and all such variations and equivalents are considered within the
scope and spirit of the present invention. Also, the terms in the
claims have their plain, ordinary meaning unless otherwise
explicitly and clearly defined by the patentee.
* * * * *