U.S. patent application number 12/974760 was filed with the patent office on 2011-06-30 for foam optimization method for deliquifying wells.
This patent application is currently assigned to BP CORPORATION NORTH AMERICA INC.. Invention is credited to Jaime Cabanilla, Bryan D. Dotson.
Application Number | 20110155378 12/974760 |
Document ID | / |
Family ID | 43533557 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110155378 |
Kind Code |
A1 |
Cabanilla; Jaime ; et
al. |
June 30, 2011 |
FOAM OPTIMIZATION METHOD FOR DELIQUIFYING WELLS
Abstract
Systems and methods for optimizing injection of a foaming
composition into a well for deliquification are disclosed herein.
Embodiments of the method generally comprise injecting a foaming
composition into a well to deliquify the well. The method may
further comprise measuring the foaming properties of the produced
fluids from the well. In addition, the method may comprise
correlating the foaming properties of the produced fluids to
production rate and then adjusting the injection rate of the
foaming composition in light of the results of the analysis.
Inventors: |
Cabanilla; Jaime; (Katy,
TX) ; Dotson; Bryan D.; (Houston, TX) |
Assignee: |
BP CORPORATION NORTH AMERICA
INC.
Warrenville
IL
|
Family ID: |
43533557 |
Appl. No.: |
12/974760 |
Filed: |
December 21, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61288604 |
Dec 21, 2009 |
|
|
|
Current U.S.
Class: |
166/309 |
Current CPC
Class: |
E21B 43/121 20130101;
E21B 21/08 20130101; C09K 8/94 20130101; C09K 8/58 20130101; E21B
43/166 20130101 |
Class at
Publication: |
166/309 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. A method of optimizing foam injection into a well comprising: a)
injecting a foam composition at a flow rate into a well to remove
liquid from the well, wherein the foam composition causes the
liquid to form a foam and allow production of produced fluids; b)
allowing produced fluids to flow from the well at an observed
production rate; c) measuring one or more foaming properties of the
produced fluids; d) correlating the one or more foaming properties
to the observed production rate to determine a relationship between
the one or more properties and the observed production rate; and e)
based on the relationship, adjusting the injection rate to optimize
injection of the foam composition into the well.
2. The method of claim 1 wherein the one or more foaming properties
measured in (c) comprises density, dynamic surface tension meter,
concentration of foam composition, foam stability, or combinations
thereof.
3. The method of claim 1 wherein the foam composition comprises
anionic surfactants, cationic surfactants, nonionic surfactants,
zwitterinoic surfactants, amphiphobic surfactants, hydrophilic
surfactants, hydrophobic surfactants, or combinations thereof.
4. The method of claim 1 wherein (c) through (e) are performed
manually.
5. The method of claim 1 wherein (c) through (e) are performed
automatically in real time.
6. The method of claim 1 wherein an initial injection rate is
determined prior to (a) based on properties of the well fluids.
7. The method of claim 1 wherein the foam composition comprises a
surfactant.
8. The method of claim 1 wherein the well is a gas well.
9. The method of claim 1 wherein (c) comprises using a dynamic
surface tension meter, a densitometer, a chemical, or combinations
thereof to measure the one or more foaming properties.
10. The method of claim 1 wherein an initial injection rate of the
foaming composition is determined prior to (a).
11. The method of claim 1 wherein (c) further comprises determining
the composition of the produced fluids.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional
application Ser. No. 61/288,604 filed Dec. 21, 2009 and entitled
"Foam Optimization Method for Deliquifying Wells", which is hereby
incorporated herein by reference in its entirety for all
purposes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND
[0003] 1. Field of the Invention
[0004] This invention relates generally to the field of production
of hydrocarbons. More specifically, the invention relates to a
method of deliquifying hydrocarbon producing wells.
[0005] 2. Background of the Invention
[0006] The accumulation of liquids such as water in a natural gas
well tends to reduce the quantity of natural gas which can be
produced from a given well. Gaseous hydrocarbons produced from
underground reservoirs will have liquids associated with them, the
presence of which can affect the flowing characteristics of the
well. Liquids can come from condensation of hydrocarbon gas
(condensate) or from interstitial water in the reservoir. In either
case, the higher density liquid-phase must be transported to the
surface by the gas. In the event the gas phase does not provide
sufficient transport energy (i.e. insufficient reservoir pressure)
to lift the liquids out of the well, the liquid will accumulate in
the well bore. The accumulation of the liquid will impose an
additional back-pressure on the formation and can significantly
affect the production capacity of the well. In low-pressure wells,
the liquid may completely kill the well.
[0007] One cost-effective technique that has been used to deliquify
wells and restore production of hydrocarbons is foam assisted lift
(FAL). The technique involves the injection of foaming agents or
compositions downhole. The foaming agents or compositions cause the
liquids to form a foam, thereby reducing surface tension, lowering
the density and allowing production fluids to be produced
again.
[0008] One of the most common methods of application of foam is by
continuous injection of a foam composition into the well. Normally,
once an initial analysis has been done with respect to the efficacy
of the foam composition on the particular production fluids and the
amount of foam composition to be injected, no more analysis is
performed. That is, once an initial flow rate has been established,
unless a problem occurs, the flow rate of the foaming agent or
composition is kept constant. Presently, the only way to determine
whether the optimal flow rate of foaming agent is being used is to
observe the produced gas flow rate over time. However, the lag time
between foam injection and gas flow rate may be on the order of
weeks to months. Thus, the foaming agent may be injected at higher
amounts than necessary for weeks, months or even years.
[0009] Consequently, there is a need for a more precise method to
optimize the input of foaming composition into a well after
production has been re-established.
BRIEF SUMMARY
[0010] Systems and methods for optimizing injection of a foaming
composition into a well for deliquification are disclosed herein.
Embodiments of the method generally comprise injecting a foaming
composition into a well to deliquify the well. The method may
further comprise measuring the foaming properties of the produced
fluids from the well. In addition, the method may comprise
analyzing the foaming properties of the produced fluids and then
adjusting the injection rate of the foaming composition in light of
the results of the analysis.
[0011] In an embodiment, a method of optimizing foam injection into
a well comprises injecting a foam composition at a flow rate into a
well to remove liquid from the well. The foam composition causes
the liquid to form a foam and allow and/or enhance production of
produced fluids. The method further comprises allowing the produced
fluids to flow from the well at an observed production rate. The
method also comprises measuring one or more foaming properties of
the produced fluids. In addition, the method comprises correlating
the one or more foaming properties to the observed production rate
to determine a relationship between the one or more properties and
the observed production rate. The method also comprises based on
the relationship, adjusting the injection rate to optimize
injection of the foam composition into the well.
[0012] The foregoing has outlined rather broadly the features and
technical advantages of the 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 that form the subject of the claims of the
invention. It should be appreciated by those skilled in the art
that the conception and the specific embodiments disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the invention. It
should also be realized by those skilled in the art that such
equivalent constructions do not depart from the spirit and scope of
the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a detailed description of the preferred embodiments of
the invention, reference will now be made to the accompanying
drawings in which:
[0014] FIG. 1 illustrates an embodiment of a system and method for
optimizing foam injection into a well;
[0015] FIG. 2 illustrates an embodiment of a method for optimizing
foam injection into a well; and
[0016] FIG. 3 illustrates sample plots of correlating foaming
properties with production rate and injection rate.
NOTATION AND NOMENCLATURE
[0017] Certain terms are used throughout the following description
and claims to refer to particular system components. This document
does not intend to distinguish between components that differ in
name but not function.
[0018] In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ". Also, the term "couple" or "couples" is intended to mean
either an indirect or direct connection. Thus, if a first device
couples to a second device, that connection may be through a direct
connection, or through an indirect connection via other devices and
connections.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] FIG. 1 illustrates an embodiment of the method for
optimizing foam injection in the deliquification of wells. FIG. 1
depicts a typical production well. In particular, a well 110 may
include without limitation, surface casing 111, production casing
113, and surface valves 117. However, embodiments of the system 100
also may be used in uncased wells. Hydrocarbons (i.e. oil or gas)
may enter the well 110 through perforations 118 from a formation
119 in the casing 113 which allow hydrocarbons from the formations
to enter the well 110 and be produced through tubing 101. FIG. 1
shows a well 110 with a first formation 119. Other components of a
production well are not shown and are well known in the art.
[0020] Generally, the method is outlined in FIG. 2. The method may
comprise injecting a foaming composition into a well 110 at an
initial injection rate. As defined herein, the term "foaming
composition" may refer to any composition which leads to the
formation of foam as opposed to merely reducing the density of a
liquid. Once the foaming composition has been injected, the method
may comprise producing the fluids from the well. The method may
further comprise measuring the foaming properties of the produced
fluids to determine the optimum level of injection, and adjusting
the injection rate of the foam composition accordingly.
[0021] The foam composition may be injected into well 110 by any
means known to those of skill in the art. As depicted in FIG. 1,
the foam composition may be injected using a continuous
application. In a continuous application, foam compositions are
stored in tank 152 and continuously pumped into annulus of well 110
using a surface pump 150. Other forms of continuous application of
foam compositions are also contemplated including without
limitation, annular, capillary string, velocity string, coil
tubing, gas lift, or combinations thereof. Alternatively, foam
composition may be injected into well 110 by cyclical batch
treatment via annulus. The initial injection rate of the foaming
composition may be determined using any techniques commonly known
to those of skill in the art. Upon injection of the foaming
composition and flow of produced fluids from the well has been
re-established, the foaming properties of the produced fluids and
the hydrocarbon production rate may be immediately measured.
Alternatively, the produced fluids may be allowed to flow without
measurement for a stabilization period and then measured.
[0022] In an embodiment, once production of the well 110 has been
re-established (i.e. a steady production of hydrocarbons) injection
of the foam composition may be halted while well production is
maintained. The foaming properties of the produced fluids and the
production rate of the fluids may be measured and recorded
simultaneously until the production from the well halts or becomes
erratic. Without being limited by theory, as shown in the plots in
FIG. 3, as the amount of foaming composition decreases over time,
the minimal level of foaming composition necessary to deliquify the
well will eventually be reached and the production rate of the well
will either halt or become erratic. During the decline in
production, one or more foaming properties of the produced fluid
may be continuously measured or measured at intervals. The one or
more foaming properties of the produced fluid right before the
production rate of the well becomes unstable or halts, likely
represents the optimum level of foaming composition in the
production fluid. The one or more foaming properties at this point
may be correlated to an optimum injection rate of the foaming
composition. In other words, the optimum injection rate of the
foaming composition should correspond to an injection rate that
will maintain the minimum level of foaming composition in the well
to cause sufficient foaming for deliquification of the well. In
further embodiments, the method is not limited to foam properties.
Other properties may also be measured such as bottom hole pressure,
downhole temperature, downhole concentration, etc. These properties
may also be correlated to injection rate and production rate.
[0023] Alternatively, the injection rate of foaming composition may
be set initially at a very low level while the production rate of
the well is monitored. The injection rate may then be increased to
second flow rate while the production rate of the well is
monitored. This process may be repeated until production of the
well is re-established. At such point, the foaming properties of
the produced fluids may be measured and analyzed. Again, the
foaming properties may be correlated to an optimum injection rate
of foam. The correlation of foaming properties to injection rate
may be applicable to several wells having the same produced fluids
properties.
[0024] Testing the produced foam and/or fluids comprises sensing
various properties of the produced fluids to determine if the
produced fluid is at the proper foaming level. Sensing a property
of the produced fluids may be accomplished by any methods known to
those of skill in the art. For example, a sample of produced
foam/fluids may be analyzed at the well site manually by a
technician using any number of known techniques. Examples of such
techniques include without limitation, densitometers, dynamic
surface tension instruments, blender or foam column tests, chemical
tests, fluorescence tests, tracer tests, or combinations thereof.
For example, a chemical test may be used to measure/detect the
amount or concentration of foaming composition within a produced
fluid. In addition, dynamic surface tension instruments are known
and are described in more detail in Colloids and Surfaces A:
Physicochem. Eng. Aspects 309 (2007) 177-181, herein incorporated
by reference and attached in Appendix A.
[0025] Once an operator has analyzed the sample and determined a
foaming level, he/she may compare and correlate the foaming
property with the injection rate of the foaming composition. It is
emphasized that measuring/sensing physical foam properties of the
produced fluids is distinct and different from simply measuring
flow rate or production rate of the produced fluid. By analyzing
the foam properties of the produced fluid a more accurate
assessment may be made of the efficacy of injection rate of the
foaming composition. In addition, the measured foam properties of
the produced fluid may be stored or recorded in a database for
future reference. The data may be used to create correlations and
trends between foaming composition, foaming concentration, and foam
injection rate to specific types of produced fluid or wellbore
configurations. Specifically, wells drilled into the same reservoir
may have produced fluids with the same properties. Using the data
gained from a single well, the initial injection rate may be more
accurately determined for other wells drilled in the same
reservoir.
[0026] Referring back to FIG. 1, in another embodiment, the foaming
properties of the produced fluids may be sensed automatically in
real time, with the resulting data fed into and analyzed by a
system 153 in real time. In one embodiment, control system 153 may
be a programmable logic controller. The control system 153 may
comprise a microprocessor having a memory, inputs, outputs, and an
operator interface. The operator interface may be either local or
remote via telemetry and may include conventional components such
as a keyboard, a display monitor or a printer. The inputs, outputs
and operator interface enable operator interaction with the control
system 153 as described hereafter. The control system 153 may be
electronically linked to the pump controller 155 or the pump 150 as
shown by the arrows, enabling the control system 153 to receive
feedback signals from the sensors or measuring devices 160, and
enabling the control system 153 to transmit operating instruction
signals to pump controller 155. In particular, foaming properties
of the produced fluid which may be sensed may include without
limitation, density of the produced fluids, surface dynamic
tension, concentration of the foam composition, critical micelle
concentration, chemical presence of the foam composition within the
produced fluids, or combinations thereof. These foaming properties
may be measured using the techniques described above. The sensed
properties of the produced fluid may be analyzed by a control
system 153 (i.e. computer) to determine the sufficiency of foaming
or the foaming level of the produced fluids/foam. Depending on the
sensed properties of the produced fluids and the outcome of the
analysis by control system 153, control system 153 may send a
signal to pump controller 155 to either increase or decrease the
flow rate of foam composition being injected or pumped into well
110.
[0027] The one or more sensors 160 may be connected to a control
system 153, which may be a computer with the necessary computer
programs and software to perform the necessary calculations,
correlations, comparisons and determinations of whether the foaming
properties of the produced fluids are optimal. The control system
153 may issue the proper commands to a pump controller 155 to
control the injection of one or more foam compositions into the
wellbore. In some embodiments, more than one pump controller 155
may be utilized. In response to the commands received from the
sensor 160 or control system 153, the pump controller 155 may
adjust the pump 150 to either decrease or increase the flow rate of
the foam composition. It is contemplated that additional valves,
flow controllers, pumps, may be used with the embodiment shown in
FIG. 1 to fine tune and control the system as much as needed.
[0028] The foaming composition that may be injected to the well 110
may be any compositions known to those of skill in the art in foam
assisted lift. Examples of suitable foam compositions include
without limitation, anionic surfactants, cationic surfactants,
nonionic surfactants, zwitterinoic surfactants, amphiphobic
surfactants, hydrophilic surfactants, hydrophobic surfactants, or
combinations thereof. The foaming composition may be a single
chemical or a mixture of chemicals. In addition to decreasing the
surface tension between the formation fluid, the foam compositions
useful with the disclosed methods may be non-corrosive. Such
compositions include all sultaines and all salts thereof, and all
hydroxy sultaines and all salts thereof. The compositions useful
with the present application, when prepared with a surfactant, are
prepared using solvents that do not strip off at the formation
temperature or well operating temperature. In the method of the
present invention, the composition is preferably formulated using
solvents, if any, which will not leave residue on the system.
Examples of suitable foaming compositions are described in more
detail in U.S. patent application Ser. No. 10/477,241, incorporated
herein by reference.
[0029] While the embodiments of the invention have been shown and
described, modifications thereof can be made by one skilled in the
art without departing from the spirit and teachings of the
invention. The embodiments described and the examples provided
herein are exemplary only, and are not intended to be limiting.
Many variations and modifications of the invention disclosed herein
are possible and are within the scope of the invention.
Accordingly, the scope of protection is not limited by the
description set out above, but is only limited by the claims which
follow, that scope including all equivalents of the subject matter
of the claims.
[0030] The discussion of a reference is not an admission that it is
prior art to the present invention, especially any reference that
may have a publication date after the priority date of this
application. The disclosures of all patents, patent applications,
and publications cited herein are hereby incorporated herein by
reference in their entirety, to the extent that they provide
exemplary, procedural, or other details supplementary to those set
forth herein.
* * * * *