U.S. patent application number 12/826856 was filed with the patent office on 2012-01-05 for method for in situ fluid assessment and optimization during wellbore displacement operations.
This patent application is currently assigned to Chevron U.S.A. Inc.. Invention is credited to John Cameron, Earl J. Coludrovich, III, Thomas G. Corbett, H. Mitchell Cornette.
Application Number | 20120000658 12/826856 |
Document ID | / |
Family ID | 45398816 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000658 |
Kind Code |
A1 |
Coludrovich, III; Earl J. ;
et al. |
January 5, 2012 |
METHOD FOR IN SITU FLUID ASSESSMENT AND OPTIMIZATION DURING
WELLBORE DISPLACEMENT OPERATIONS
Abstract
The present invention is, in some embodiments directed to
methods for optimizing wellbore displacement operations via in situ
fluid property assessment/monitoring. By monitoring fluid
properties in situ (i.e., downhole), fluid property assessment is
direct instead of being inferred. Additionally, wherein such
assessment/monitoring is carried out in real time, changes to the
displacement fluid can be made "on-the-fly," thereby contributing
to an enhancement of the overall efficiency of the method.
Inventors: |
Coludrovich, III; Earl J.;
(Missouri City, TX) ; Cornette; H. Mitchell;
(Houston, TX) ; Corbett; Thomas G.; (Willis,
TX) ; Cameron; John; (Woodlands, TX) |
Assignee: |
Chevron U.S.A. Inc.
San Ramon
CA
|
Family ID: |
45398816 |
Appl. No.: |
12/826856 |
Filed: |
June 30, 2010 |
Current U.S.
Class: |
166/305.1 |
Current CPC
Class: |
E21B 47/10 20130101;
E21B 21/00 20130101 |
Class at
Publication: |
166/305.1 |
International
Class: |
E21B 43/16 20060101
E21B043/16 |
Claims
1. A method for in situ downhole monitoring of fluids in a well
during fluid displacement operations, said method comprising the
steps of: a) introducing a quantity of spacer fluid into a well via
a workstring, said well initially occupied by a solids-laden
working fluid, the spacer fluid establishing a first interface
between it and the solids-laden working fluid; b) following the
spacer fluid introduction with a completion fluid, a second
interface being established between the completion fluid and the
spacer fluid; c) monitoring, in situ, at least one fluid selected
from the group consisting of working fluid, spacer fluid, and
completion fluid, as said fluid is displaced up the annular region
of the well; wherein such monitoring provides an in situ fluid
property assessment of at least one fluid property; and d)
communicating the in situ fluid property assessment uphole for
purposes of facilitating wellbore displacement operations.
2. The method of claim 1, wherein the well is operable for
producing hydrocarbons, wherein said hydrocarbons are selected from
the group consisting of oil, gas, and combinations thereof, and
wherein the well is selected from the group consisting of a
land-based well and an offshore well.
3. The method of claim 1, wherein the at least one fluid property
is selected from the group consisting of turbidity, density, solids
concentration, capacitance, viscosity, resistivity, temperature,
pressure, radioactivity, salinity, basic sediment and water, and
combinations thereof.
4. The method of claim 1, wherein the solids laden working fluid is
selected from the group consisting of drilling fluids, workover
fluids, brine systems, and combinations thereof.
5. The method of claim 1, wherein the spacer fluid is introduced as
a pill.
6. The method of claim 5, wherein the spacer fluid is introduced as
a series of pills exhibiting a progressive variation in at least
one property across the series.
7. The method of claim 5, wherein the spacer fluid is compatible
with both the solids-laden working fluid and the completion
fluid.
8. The method of claim 1, wherein said step of monitoring is
carried out in a manner selected from the group consisting of
continuous monitoring, discrete monitoring, and combinations
thereof.
9. The method of claim 1, wherein the step of monitoring requires a
plurality of fluid property analyzers positioned in said well to
monitor the at least one fluid.
10. The method of claim 9, wherein at least some of the plurality
of fluid property analyzers provide fluid assessment of different
fluid properties.
11. The method of claim 9, wherein the plurality of fluid property
analyzers are positioned at different locations in the well, so as
to monitor fluids at different points along the annular region of
the well.
12. The method of claim 1, wherein the step of communicating
involves cabled communication of fluid property analyzer data.
13. The method of claim 1, wherein the step of communicating
involves wireless communication of fluid property analyzer
data.
14. The method of claim 13, wherein wireless communication is of a
form selected from the group consisting of pressure pulses,
acoustic transmissions, electromagnetic transmissions, and
combinations thereof.
15. The method of claim 1, further comprising a step of
facilitating optimization of wellbore displacement operations,
wherein optimization is afforded by real time assessment of fluid
properties.
16. A method for in situ downhole monitoring of fluids in a well
during fluid displacement operations, said well being operable for
producing hydrocarbons, and said method comprising the steps of: a)
introducing a quantity of spacer fluid into a well via a
workstring, said well initially occupied by a solids-laden working
fluid, the spacer fluid establishing a first interface between it
and the solids-laden working fluid, wherein the solids laden
working fluid is selected from the group consisting of drilling
fluids, workover fluids, brine systems, and combinations thereof;
b) following the spacer fluid introduction with a completion fluid,
a second interface being established between the completion fluid
and the spacer fluid; c) monitoring, in situ, at least one fluid
selected from the group consisting of working fluid, spacer fluid,
and completion fluid, as said fluid is displaced up the annular
region of the well; wherein such monitoring provides an in situ
fluid property assessment of at least one fluid property selected
from the group consisting of turbidity, density, solids
concentration, capacitance, viscosity, resistivity, temperature,
pressure, radioactivity, salinity, basic sediment and water
(BS&W), and the like, and combinations thereof; d)
wirelessly-communicating the in situ fluid property assessment
uphole, wherein such wireless communication is of a form selected
from the group consisting of pressure pulses, acoustic
transmissions, electromagnetic transmissions, and combinations
thereof; and e) facilitating optimization of wellbore displacement
operations, wherein optimization is afforded by real time
assessment of fluid properties in situ.
17. The method of claim 16, wherein the spacer fluid is introduced
as a pill.
18. The method of claim 17, wherein the spacer fluid is introduced
as a series of pills exhibiting a progressive variation in at least
one property across the series.
19. The method of claim 16, wherein the step of monitoring requires
a plurality of fluid property analyzers are positioned in said well
to monitor the at least one fluid, and wherein at least some of the
plurality of fluid property analyzers provide fluid assessment of
different fluid properties.
20. The method of claim 19, wherein the plurality of fluid property
analyzers are positioned at different locations in the well, so as
to monitor fluids at different points along the annular region of
the well.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to wellbore completion
operations, and specifically to methods for assessing and/or
optimizing wellbore fluid displacement operations.
BACKGROUND
[0002] Numerous situations and/or scenarios exist in which wells
are extended to subterranean locations in the earth's crust. For
example, wells are drilled into subterranean/geologic formations in
order to provide for the production of a variety of fluids, such as
water, gas and/or oil; or for the injection of fluids, such as is
employed in the secondary and tertiary recovery of oil (e.g.,
enhanced oil recovery). In many such situations and/or scenarios,
in order to properly support the wall of the well, and possibly to
exclude fluids from undesirably traversing the boundaries of at
least some portions of the well, the well is cased with one or more
strings of pipe, i.e., casing strings.
[0003] In order to complete the well, the casing must be bonded to
the formation using a cementing procedure. Cementing procedures
typically involve a drilling fluid displacement step, followed by a
step of pumping a cement formulation (e.g., as a slurry) through
the casing to the bottom of the well and then upwardly through the
annular space between the outer surface of the casing and the
surrounding wall structure, i.e., the formation. After the cement
formulation is in place, it is allowed to set, thereby forming an
impermeable sheath which, assuming that good bonding is established
between the cement and the formation, and the cement and the
casing, such bonding prevents the migration of fluids through the
annulus surrounding the casing. The cement bonds further enhance
the overall integrity of the well. For an example of a well
cementing procedure, see, e.g., Parker, U.S. Pat. No. 3,799,874,
issued Mar. 26, 1974.
[0004] After cementing the casing in a well, one or more cleanout
operations or procedures are typically employed to clean out the
well in preparation for production. Such procedures can vary
considerably, but often involve running a workstring down the well
with one or more cleaning tools and/or devices attached to it. Such
cleaning tools can include brushes, scrapers, drill bits (e.g., for
drilling out cement plugs, etc.), and means for delivering (and
circulating) fluids and/or chemicals to the wellbore for the
purpose of cleaning out the cased wellbore (including cleaning of
the drilling fluid contained therein) and/or the interior surfaces
of the associated casing prior to drilling fluid displacement,
perforation and subsequent production. See, e.g., Reynolds et al.,
U.S. Pat. No. 5,570,742, issued Nov. 5, 1996; Reynolds et al., U.S.
Pat. No. 5,419,397, issued May 30, 1995; Reynolds, U.S. Pat. No.
6,758,276, issued Jul. 6, 2004; and Carmichael et al., U.S. Pat.
No. 6,401,813, issued Jun. 11, 2002.
[0005] After such above-described cleanup operations, the drilling
fluid present in the wellbore must be displaced by completion
fluid, i.e., a displacement operation or procedure. However,
because completion fluids are typically incompatible (for a variety
of reasons) with drilling fluids, the completion fluid can be
preceded by a spacer fluid during a displacement operation. In some
such instances, the spacer fluid may comprise a series of fluids
having a graduated progression in value of one or more property, so
as to provide for a gradual transition from one end of a fluid
property range to the other--for at least one such fluid property.
For background and examples of such spacer fluids and their use,
see, e.g., Oliver et al., U.S. Pat. No. 4,474,240, issued Oct. 2,
1984; Thomas, U.S. Pat. No. 4,423,781, issued Jan. 3, 1984; and Ray
et al., U.S. Pat. No. 6,196,320, issued Mar. 6, 2001.
[0006] In view of the foregoing, new methods for monitoring
displacement fluids in situ would be extremely useful--particularly
wherein such a method and/or system provides greater efficiency
with respect to completions operations. Furthermore, while the
discussion which follows focuses primarily on oil and gas wells,
those of skill in the art will appreciate that at least some of the
method and system embodiments discussed herein can be extended to a
variety of displacement operations in one or more of the
situations/scenarios mentioned above.
BRIEF DESCRIPTION OF THE INVENTION
[0007] The present invention is generally directed to methods for
optimizing wellbore displacement operations via in situ fluid
property assessment/monitoring, thereby providing direct assessment
of one or more properties of one or more fluids under the
environmental conditions to which that fluid(s) experience in the
well. In some embodiments, such in situ fluid property
assessment/monitoring is performed in real time. By monitoring
fluid properties in situ (i.e., downhole), fluid property
assessment can be direct, as opposed to being inferred (as in the
prior art). Additionally, changes to the displacement fluid can be
made "on-the-fly," thereby contributing to an enhancement of the
overall efficiency in terms of time savings and reduced fluid
waste.
[0008] In some embodiments, the present invention is directed to
one or more methods for optimizing wellbore displacement
operations, such methods comprising the steps of: (a) introducing a
quantity of spacer fluid into a well via a workstring, said well
initially occupied by a solids-laden working fluid, the spacer
fluid establishing a first interface between it and the
solids-laden working fluid; (b) following the spacer fluid
introduction with a completion fluid, a second interface being
established between the completion fluid and the spacer fluid; (c)
monitoring, in situ, at least one fluid selected from the group
consisting of working fluid, spacer fluid, and completion fluid, as
said fluid is displaced up the annular region of the well; wherein
such monitoring provides an in situ fluid property assessment of at
least one fluid property (e.g., turbidity, density, solids
concentration, capacitance, viscosity, resistivity, temperature,
pressure, radioactivity, salinity, basic sediment and water
(BS&W), and the like); and (d) communicating the in situ fluid
property assessment uphole for purposes of optimizing wellbore
displacement operations. In some such method embodiments, there may
further comprise a step (e) of facilitating optimization of
wellbore displacement operations via the real-time assessment of
fluid properties communicated in step (d).
[0009] In some or other embodiments, the present invention is
directed to one or more methods for in situ downhole monitoring of
fluids in a well during fluid displacement operations, said well
being operable for producing hydrocarbons, and said method
comprising the steps of: (a') introducing a quantity of spacer
fluid into a well via a workstring, said well initially occupied by
a solids-laden working fluid, the spacer fluid establishing a first
interface between it and the solids-laden working fluid, wherein
the solids laden working fluid is selected from the group
consisting of drilling fluids, workover fluids, brine systems, and
combinations thereof; (b') following the spacer fluid introduction
with a completion fluid, a second interface being established
between the completion fluid and the spacer fluid; (c') monitoring,
in situ, at least one fluid selected from the group consisting of
working fluid, spacer fluid, and completion fluid, as said fluid is
displaced up the annular region of the well; wherein such
monitoring provides an in situ fluid property assessment of at
least one fluid property selected from the group consisting of
turbidity, density, solids concentration, capacitance, viscosity,
resistivity, temperature, pressure, radioactivity, salinity, basic
sediment and water (BS&W), and combinations thereof); (d')
wirelessly-communicating the in situ fluid property assessment
uphole, wherein such wireless communication is of a form selected
from the group consisting of pressure pulses, acoustic
transmissions, electromagnetic transmissions, and combinations
thereof; and (e') facilitating optimization of wellbore
displacement operations, wherein optimization is afforded by real
time assessment of fluid properties in situ.
[0010] The foregoing has outlined rather broadly the features of
the present invention in order that the detailed description of the
invention that follows may be better understood. Additional
features and advantages of the invention will be described
hereinafter which form the subject of the claims of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a more complete understanding of the present invention,
and the advantages thereof, reference is now made to the following
description taken in conjunction with the accompanying drawings, in
which:
[0012] FIG. 1 illustrates, in stepwise fashion, one or more methods
for optimizing wellbore displacement operations via in situ fluid
property assessment/monitoring, in accordance with one or more
embodiments of the present invention; and
[0013] FIG. 2 illustrates an exemplary variational system
embodiment for implementing one or more method embodiments
described herein.
DETAILED DESCRIPTION OF THE INVENTION
1. Introduction
[0014] As mentioned above, the present invention is generally
directed to methods (and in some instances, systems) for optimizing
wellbore displacement operations via in situ fluid property
assessment/monitoring of one or more of the fluids present in the
wellbore during the displacement operations. In some such
embodiments, such fluid property assessment/monitoring is carried
out and communicated to the surface in real time. In contrast to
existing methods (vide supra) of monitoring fluids at the surface,
by monitoring fluid properties in situ (i.e., downhole), fluid
property assessment is direct instead of by inference.
Additionally, at least to the extent that such fluid property
assessment/monitoring is performed in real time, changes to the
displacement fluid (or one or more other aspects of the
displacement operations) can be made ex tempore, thereby
contributing to an enhancement of the overall efficiency.
2. Definitions
[0015] Certain terms are defined throughout this description as
they are first used, while certain other terms used in this
description are defined below:
[0016] The term "well," as defined herein, refers to a wellbore
disposed in a geological volume, most typically for the direct or
indirect production of one or more fluids from the surrounding
geological reservoir(s).
[0017] The term "cased wellbore," as defined herein, refers to a
wellbore into which one or more casing strings have been run and
cemented into place. This definition is extended to include one or
more liner strings (in place of casing strings), wherein such liner
strings are suspended at various depths via one or more liner
hangers.
[0018] The term "displacement operations," as defined herein,
refers to the displacement of one fluid in the wellbore by another.
An exemplary such operation involves removing drilling fluid from
the well after cleanup operations and replacing it with completion
fluid.
[0019] The term "workstring," as defined herein, refers to a string
of tubulars deployed in a subterranean wellbore for the purpose of
performing tasks during the course of drilling and/or completion
operations.
[0020] The term "drilling fluid," as defined herein, refers to any
of a number of liquid and gaseous fluids and mixtures of fluids and
solids (as solid suspensions, mixtures and emulsions of liquids,
gases and solids) used in operations to drill boreholes into the
earth. Unless specifically stated otherwise, the terms "drilling
fluid" and "drilling mud" are used interchangeably herein.
[0021] The term "completion fluid," as defined herein, refers to a
substantially solids-free liquid used to "complete" an oil or gas
well. This fluid is generally placed in the well to facilitate
final operations prior to initiation of production, such as setting
screens production liners, packers, downhole valves or shooting
perforations into the producing zone. The fluid is meant to control
a well should downhole hardware fail, without damaging the
producing formation or completion components. The fluid should be
chemically-compatible with the reservoir formation and fluids, and
is typically filtered to a high degree to avoid introducing solids
to the near-wellbore area.
[0022] The term "spacer fluid," as defined herein, refers to any
liquid used to physically separate one working fluid (vide infra)
and/or completion fluid from another, wherein the spacer fluid is
compatible with both of the fluids it is being used to
separate.
[0023] The term "working fluid," as defined herein, broadly
categorizes any fluid used in well operations other than completion
fluids (and any spacer fluids used prior to the introduction of
such completion fluids). Examples of such working fluids include,
but are not limited to, drilling fluids, brine systems, workover
fluids, etc.
3. Methods
[0024] As mentioned previously herein (vide supra), methods of the
present invention provide for optimization of wellbore displacement
operations via in situ fluid property assessment/monitoring of one
or more of the fluids present in the wellbore during the
displacement operations. Additionally, where such fluid property
assessment/monitoring is carried out and communicated to the
surface in real time, changes to the displacement fluid (or one or
more other aspects of the overall operation) can be made ex
tempore, thereby permitting enhancement of the overall displacement
operation process efficiency.
[0025] With reference to FIG. 1, in some embodiments the present
invention is directed to one or more methods for in situ downhole
monitoring of fluids in a well during fluid displacement
operations, said method comprising the steps of: (Step 101)
introducing a quantity of spacer fluid into a well via a
workstring, said well initially occupied by a solids-laden working
fluid, the spacer fluid establishing a first interface between it
and the solids-laden working fluid; (Step 102) following the spacer
fluid introduction with a completion fluid, a second interface
being established between the completion fluid and the spacer
fluid; (Step 103) monitoring, in situ, at least one fluid selected
from the group consisting of working fluid, spacer fluid, and
completion fluid, as said fluid is displaced up the annular region
of the well; wherein such monitoring provides an in situ fluid
property assessment of at least one fluid property (e.g.,
turbidity, density, solids concentration, capacitance, viscosity,
resistivity, temperature, pressure, radioactivity, salinity, basic
sediment and water (BS&W), and the like); and (Step 104)
communicating the in situ fluid property assessment uphole for
purposes of facilitating wellbore displacement operations. In some
such method embodiments, there may further comprise a (Step 105) of
facilitating optimization of wellbore displacement operations via
the real time assessment of fluid properties communicated in (Step
104).
[0026] Regarding such above-described method embodiments, the type
of well to which it is applied is not particularly limited.
Accordingly, such wells can be vertical, deviated, or horizontal,
or combinations thereof. Such wells can be capable of producing
oil, gas, and/or other fluids (vide supra). Such wells are also
contemplated to include, for example, injection wells operable for
stimulating production (e.g., steam injection). Similarly, the
wells can be onshore or offshore, and in the latter case, they can
be in either shallow or deepwater. Furthermore, the wells can vary
considerably over a wide range of depths and/or lengths, and the
methods can typically be tailored so as accommodate the particular
procedures unique to any or all of such wells (e.g., unique to oil
wells).
[0027] In some such above-described method embodiments, the
solids-laden working fluid is selected from the group consisting of
drilling fluids, workover fluids, brine systems, and combinations
thereof. Solids present in the working fluid can be from a variety
of sources (e.g., from the cleanout operations done previously, and
native components of the fluid composition), of a variety of
dimensions, and of a variety of compositions. Depending upon the
embodiment, the solids-laden working fluids can be aqueous-based,
non-aqueous-based (e.g., oil-based), or emulsion-based (e.g., an
oil/water emulsion). By "-based" attention is directed to the base
or primary fluid of which the working fluid is comprised.
Typically, this base fluid would be that component present in the
working fluid composition in greatest amount (e.g., by volume),
and/or that component from which the properties of the resulting
composition are largely derived. For a variety of reasons, largely
relating to formation incompatibility and/or productivity
impairment, the composition of such fluids typically precludes
their use as completion fluids.
[0028] By way of example and not limitation, suitable such
above-mentioned drilling fluids can include, but are not limited
to, mixtures of bentonite clay with water and/or oil, as well as
one or more additives such as weighting agents (e.g., barite),
viscosifiers, and/or deflocculants. In some instances, drilling
fluids can be foams. For background and examples of these and
similarly-suitable such drilling fluids, see, e.g., Patel et al.,
U.S. Pat. No. 7,250,390, issued Jul. 31, 2007; Rayborn et al., U.S.
Pat. No. 5,843,872, issued Dec. 1, 1998; and Peacock, U.S. Pat. No.
3,215,628, issued Nov. 2, 1965.
[0029] In some such above-described embodiments wherein the working
fluid is or comprises a workover fluid, exemplary such workover
fluids include, but are not limited to, those well intervention
fluids used to control a well during one or more workover
operations. The workover fluids must generally be compatible with
the formation and are typically brine or brine-based. For the
purposes of this description, some kill fluids, i.e., those fluids
used for stopping flow of production fluids out of a well, can be
considered workover fluids--at least to the extent that they are
utilized to kill the well in advance of a workover. Background and
examples on workover fluids can be found in Sydansk, U.S. Pat. No.
5,682,951, issued Nov. 4, 1997; Shell, U.S. Pat. No. 4,559,149,
issued Dec. 17, 1985; and Gruesbeck et al., U.S. Pat. No.
4,046,197, issued Sep. 6, 1977.
[0030] In some such above-described embodiments wherein the working
fluid is or comprises a brine system, exemplary such brine systems
include, but are not limited to, brine-based fluids, typically
comprising one or more of a variety of additive species. Background
and examples on such brine systems can be found in, e.g., Murphey,
U.S. Pat. No. 6,124,244, issued Sep. 26, 2000.
[0031] Spacer fluids are generally described in Ray et al., U.S.
Pat. No. 6,196,320, issued March 2001; and Thomas, U.S. Pat. No.
4,423,781, issued Jan. 3, 1984. In some such above-described method
embodiments, the spacer fluid can be viewed a spacer system
comprising a plurality of components and/or a progression of
components/properties as it is introduced into the well. In some
such embodiments, such spacer fluids enhance compatibility and/or
promotes or inhibits mixing of fluids at one or both of the first
and second fluid interfaces.
[0032] In some such above-described method embodiments, the spacer
fluid is introduced as a pill, wherein such a pill can be either
substantially homogenous or inhomogeneous (in terms of composition
and/or physiochemical properties) along the length of its
introduction and/or its cross-section, wherein such inhomogeneity
can be slight, moderate, or substantial in character. In some such
method embodiments, the spacer fluid is introduced as a series of
pills exhibiting a variation in at least one property between
adjacent pills.
[0033] In some such above-described method embodiments, the spacer
fluid is compatible with both the solids-laden working fluid and
the completion fluid. By "compatible," it is meant that the spacer
fluid does not cause degradation or alteration of the physical
and/or chemical properties of the other fluid(s) with which it
shares an interface.
[0034] In some such above-described method embodiments, the spacer
fluid permits mixing at the interface. In some or other
embodiments, the spacer fluid serves to inhibit or at least curtail
mixing of fluids at a fluid interface in the well. In some such
embodiments, such above-mentioned fluid compatibility neither
effects nor precludes such interfacial mixing (vide supra).
[0035] In some such above-described method embodiments, the spacer
fluid (or spacer fluid system) is preceded by a scrubber spacer
and/or followed by a chase spacer. Such scrubber and chase spacers
can be viewed either as components of a single (e.g.,
inhomogeneous) spacer fluid pill, or as a series of spacer fluid
pills collectively representing a spacer train. Such spacer systems
are known in the art and are described in, for example, Thomas,
U.S. Pat. No. 4,423,781, issued Jan. 3, 1984.
[0036] Completion fluids generally used in at least some of the
above-described method embodiments are not particularly limited.
Those of skill in the art will recognize that a wide variety of
compositions can be used for such fluids, but that they are
generally free of large solids. Background on completion fluids and
exemplary such compositions can be found in, e.g., Walker et al.,
U.S. Pat. No. 4,444,668, issued Apr. 24, 1984; Loftin et al., U.S.
Pat. No. 4,440,649, issued Apr. 3, 1984; Fischer et al., U.S. Pat.
No. 3,882,029, issued May 6, 1975; Peterson, U.S. Pat. No.
4,780,220, issued Oct. 25, 1988; McLaughlin, U.S. Pat. No.
4,462,718, Jul. 31, 1984.
[0037] In some such above-described method embodiments, monitoring,
in situ, the working fluid, the spacer fluid, and/or the completion
fluid, as such a fluid is displaced up the annular region of the
well, typically involves one or more fluid property analyzers
operable for fluid property assessment of at least one fluid
property. Exemplary such fluid properties include, but are not
limited to, (e.g., turbidity, density, solids concentration,
capacitance, viscosity, resistivity, temperature, pressure,
radioactivity, salinity, basic sediment and water (BS&W), and
combinations thereof--under conditions found in the wellbore, i.e.,
in situ. Depending on the embodiment and the property under
investigation, such fluid properties can be monitored directly or
indirectly by inference from a directly measurable property. While
ex situ fluid property analyzers/monitors are known in the art,
they are designed for use at the surface of the well, not under
temperatures and pressures found inside the well. See the following
for background and examples of turbidity analyzers/monitors:
Sweeney, U.S. Pat. No. 3,215,272, issued Nov. 2, 1965; Abrams et
al., U.S. Pat. No. 4,436,635, issued Mar. 13, 1984; Malbrel et al.,
U.S. Pat. No. 5,439,058, issued Aug. 8, 1995; and Sollee et al.,
"Field Application of Clean Fluids," SPE Annual Technical
Conference and Exhibition, Las Vegas, Nev., Sep. 22-26, 1985, Paper
No. 14318. See the following for background and examples of density
analyzers/monitors: Fischer et al., U.S. Pat. No. 3,882,029, issued
May 6, 1975; Betancourt et al., "Exploration Applications of
Downhole Measurement of Crude Oil Composition," SPE Asia Pacific
Conference on Integrated Modelling for Asset Management, Kuala
Lumpur, Malaysia, Mar. 29-30, 2004, Paper No. 87011; and Ryan et
al., "Mud Clean-Up in Horizontal Wells: A Major Joint Industry
Study," SPE Annual Technical Conference and Exhibition, Dallas,
Tex., Oct. 22-25, 1995, Paper No. 30528. See the following for
background and examples of viscometers (i.e., instruments for
assessing viscosity): Watson, U.S. Pat. No. 4,141,843, issued Feb.
27, 1979; Kennedy et al., U.S. Pat. No. 2,957,338, issued Oct. 25,
1960; and Saasen et al., "Well Cleaning Performance," IADC/SPE
Drilling Conference, Dallas, Tex., Mar. 2-4, 2004, Paper No. 87204.
See the following for background and examples of solids
concentration analyzers/monitors: Jones et al., U.S. Pat. No.
5,360,738, issued Nov. 1, 1994.
[0038] In some such above-described method embodiments, at least
one of the one or more fluid property analyzers (assessment tools)
is affixed to an interior surface of the workstring. In some such
embodiments, there may be a recessed portion of the workstring pipe
(possibly a "sub") in which the at least one such fluid property
analyzer resides, and/or there may be one or more coverings and/or
other devices to protect any or all of said fluid property
analyzers. In some or other embodiments, at least one of the one or
more fluid property analyzers is affixed to an exterior of the
workstring. In such latter instances, the one or more analyzers can
be affixed directly to the workstring's exterior pipe and/or in a
recessed portion thereof. Where affixation is in a recessed portion
of said workstring pipe, the one or more analyzers can still be
allowed to protrude out beyond the workstring pipe outer diameter
(OD).
[0039] In some such above-described method embodiments, said step
of monitoring is carried out in a manner selected from the group
consisting of continuous monitoring, discrete monitoring, and
combinations thereof. For the purposes of this invention,
continuous monitoring is contemplated to include discrete
monitoring with timescales of 1 analysis per second or faster. The
monitoring is deemed discontinuous or discrete at timescales slower
than 1 analysis per second.
[0040] In some such above-described method embodiments, the step of
monitoring requires a plurality of fluid property analyzers are
positioned in said well to monitor the at least one fluid. Wherein
a plurality of such analyzers are employed, any or all of them can
be used for continuous and/or discrete monitoring of any or all of
the fluid properties under assessment. In some such embodiments, at
least some of the plurality of fluid property analyzers provide
fluid assessment of different fluid properties. In some or other
such embodiments, the plurality of fluid property analyzers arc
positioned at different locations in the well, so as to monitor
fluids at different points along the annular region of the
well.
[0041] Depending on the embodiment, and by way of example and not
limitation, the fluid property analyzers employed in at least some
of the embodiments of the present invention can be powered via
batteries and/or other electrical means (e.g., wireline or wet
connect), or they can be powered wirelessly via, e.g., one or more
resonant capacitive and/or inductive circuits. Depending on the
embodiment, it is contemplated that a plurality of power delivery
means could be used to power a plurality of different types of
fluid property analyzers at multiple locations--in the same
well.
[0042] Similar to the above-described power conveyance, in some
such above-described method embodiments, the step of communicating
can involve either or both of cabled and wireless communication of
fluid property analyzer data. In some such above-described method
embodiments, wireless communication (i.e., transmission) of data up
(and/or down) a well is of a form selected from the group
consisting of pressure pulses, acoustic transmissions,
electromagnetic transmissions, and combinations thereof.
[0043] In some embodiments, where wireless transmission of data is
relied upon, such wireless transmission of data can be at least
partially provided by mud-based telemetry methods and/or acoustic
transmissions. Such techniques are known in the art and will not be
described here in further detail. For examples of such mud-based
telemetry methods, see, e.g., Kotlyar, U.S. Pat. No. 4,771,408,
issued Sept. 13, 1988; and Beattie et al., U.S. Pat. No. 6,421,298,
issued Jul. 16, 2002. For examples of wireless transmission of data
(and power) up and/or down a well using acoustic transmissions,
see, e.g., Klatt, U.S. Pat. No. 4,215,426, issued Jul. 29, 1980;
and Drumbeller, U.S. Pat. No. 5,222,049, issued Jun. 22, 1993.
[0044] In some embodiments, electromagnetic (EM) transmissions of a
type described in, for example, Briles et al., U.S. Pat. No.
6,766,141, issued Jul. 20, 2004, are used to transmit data and/or
power into and out of the cased wellbore. The downhole resonant
circuits used in such methods and systems can be integrated
directly or indirectly with the one or fluid property analyzers, so
as to convey information into, and out of, the well. See also,
e.g., Coates et al., U.S. Pat. No. 7,636,052, issued Dec. 22, 2009;
Thompson et al., U.S. Pat. No. 7,530,737, issued May 12, 2009;
Coates et al., U.S. Patent Appl. Pub. No. 20090031796, published
Feb. 5, 2009; and Coates et al., U.S. Patent Appl. Pub. No.
20080061789, published Mar. 13, 2008, wherein such "infinite
communication" systems and methods are additionally referred to as
"INFICOMM."
[0045] In some such above-described method embodiments, such
methods may further comprise a step of optimizing wellbore
displacement operations, wherein optimization is afforded by real
time assessment of fluid properties. By "real time," it is
typically contemplated that this term refer to timescales for
communicating fluid analysis data out of the well, as well as any
subsequent interpretation of said data, wherein such timescales are
substantially instantaneous or at least less than about 1
second.
[0046] In some such above-mentioned method embodiments, data (from
the fluid property analyzer(s)) is collected and stored in memory.
Such memory storage of data is not particularly limited (hard
drives, flash drives, optical drives, etc.), but must generally be
able to withstand the environmental conditions present downhole. In
some cases, storage containers can be configured to afford such
memory drives protection from adverse downhole environments.
Additionally or alternatively, in some embodiments the memory
storage device is positioned uphole from the sensors, and data
transmission between the sensor and the storage device occurs via
cabled and/or wireless means. In some embodiments, the memory
storage is at the surface. It goes without saying, however, that an
exclusive reliance on downhole storage of data, wherein the step of
communicating said data merely involves physically transporting the
storage device to the surface, may generally preclude any real time
fluid property assessment and any impromptu optimization
opportunities that might otherwise be realized through real time
assessment.
5. Variations
[0047] While the aforementioned embodiments are generally directed
to methods for optimizing wellbore displacement operations via in
situ fluid property assessment/monitoring, some variational
embodiments are directed to corresponding system embodiments that
describe, in largely functional terms, the infrastructure required
to implement one or more method embodiments of the present
invention.
[0048] As a non-limiting example, attention is now directed to FIG.
2 depicting an exemplary such system for optimizing displacement
operations via real time, in situ monitoring of fluids. Shown in
FIG. 2, in accordance with one or more embodiments of the present
invention is exemplary system 20, wherein wellbore 22 is
established in geological formation 24, and wherein wellbore 22 has
disposed within it workstring 29. In addition to having bottom hole
assembly (BHA) 39 attached at its end, workstring 29 has attached
to it a first fluid analyzer 35 and a second fluid analyzer
33--both of which have integral wireless communication means for
communicating data through wellbore 22 to surface 26. Solids-laden
working fluid 60, having previously been pumped downhole (in the
form of drilling fluid), is displaced from the well by completion
fluid 58 using spacer fluid 59 in juxtaposition between them.
[0049] As the fluids emanate from BHA 39 and migrate up the annular
region of wellbore 22, they are analyzed by fluid analyzers 35 and
33 so that, for example, the cleanliness (e.g., in terms of
turbidity) of completion fluid 58 can be ascertained by fluid
analyzer 35 before drilling fluid 60 has been completely eliminated
from wellbore 22. Furthermore, turbidity (and/or another property)
data can be wirelessly communicated from fluid analyzer 35 and/or
fluid analyzer 33 to data processing unit 41 via wireless
communication receiver 43, whereby data processing unit 41 provides
quantitative real time assessment of fluid turbidity (processed
data) at the position of fluid analyzers 35 and 33. This processed
data is then fed to control unit 46, whose job it is to control
valves in pump/manifold 47 such that the flow of any one of fluids
58-60 through conduit 49 can be controlled during displacement
operations. Integration of data processing unit 41 with
pump/manifold 47 via control unit 46 affords those fielding such a
system the ability to make changes in the displacement operations
extemporaneously.
[0050] Other variations on the above-described method embodiments,
involve inclusion of one or more tracer and/or taggant species to
one or more of the fluids to yield one or more "traceable fluids"
and/or "tagged fluids," and monitoring the said one or more
traceable or tagged fluids for said one or more tracer and/or
taggant species. Exemplary such tracers/taggants include, but are
not limited to, chemical tracers (e.g., having unique molecular
and/or isotopic signatures), radioactive tracers, and/or electrical
tracers (e.g., radio-frequency identification (RFID) tags).
6. Summary
[0051] As described throughout, the present invention is directed
to methods for optimizing wellbore displacement operations via in
situ fluid property assessment/monitoring, wherein in some such
method embodiments, said assessment/monitoring is carried out (and
processed) in real time. By monitoring fluid properties in situ
(i.e., downhole), fluid property assessment is direct instead of
being inferred. Additionally, changes to the displacement fluid can
be made "on-the-fly," i.e., extemporaneously, thereby contributing
to an enhancement of the overall efficiency. To an extent not
inconsistent with the method embodiments described herein, the
present invention is further directed to variational system
embodiments--generally for implementing one or more methods of the
present invention.
[0052] All patents and publications referenced herein are hereby
incorporated by reference to an extent not inconsistent herewith.
It will be understood that certain of the above-described
structures, functions, and operations of the above-described
embodiments are not necessary to practice the present invention and
are included in the description simply for completeness of an
exemplary embodiment or embodiments. In addition, it will be
understood that specific structures, functions, and operations set
forth in the above-described referenced patents and publications
can be practiced in conjunction with the present invention, but
they are not essential its practice. It is therefore to be
understood that the invention may be practiced otherwise than as
specifically described without actually departing from the spirit
and scope of the present invention as defined by the appended
claims.
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