U.S. patent application number 15/312672 was filed with the patent office on 2017-06-29 for controlled delivery of heat applied to a subsurface formation.
The applicant listed for this patent is Erik H. Clayton, Michael W. Lin. Invention is credited to Erik H. Clayton, Michael W. Lin.
Application Number | 20170183949 15/312672 |
Document ID | / |
Family ID | 53276250 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170183949 |
Kind Code |
A1 |
Clayton; Erik H. ; et
al. |
June 29, 2017 |
Controlled Delivery of Heat Applied To A Subsurface Formation
Abstract
The present disclosure provides a method for controlling
delivery of heat to a subsurface formation that includes (a)
heating a first heater pattern; (b) determining an expected
electrical conductivity; (c) calculating an estimated electrical
conductivity; (d) comparing an estimated electrical conductivity to
the expected electrical conductivity until the estimated electrical
conductivity equals the expected electrical conductivity; (e)
determining a first heater pattern reaction extent when the
estimated electrical conductivity equals the expected electrical
conductivity; and (f) when the first heater pattern reaction extent
is within a target coke first heater pattern reaction extent range,
one of (i) heating a second heater pattern instead of the first
heater pattern and (ii) modifying the heating of the first heater
pattern, and when the first heater pattern reaction extent is
outside of the target coke first heater pattern reaction extent
range repeating steps (a)-(e).
Inventors: |
Clayton; Erik H.; (The
Woodlands, TX) ; Lin; Michael W.; (Bellaire,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Clayton; Erik H.
Lin; Michael W. |
The Woodlands
Bellaire |
TX
TX |
US
US |
|
|
Family ID: |
53276250 |
Appl. No.: |
15/312672 |
Filed: |
April 29, 2015 |
PCT Filed: |
April 29, 2015 |
PCT NO: |
PCT/US2015/028272 |
371 Date: |
November 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62031093 |
Jul 30, 2014 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 36/04 20130101;
E21B 43/2401 20130101; E21B 49/00 20130101; E21B 43/30
20130101 |
International
Class: |
E21B 43/24 20060101
E21B043/24; E21B 49/00 20060101 E21B049/00 |
Claims
1. A method for controlling delivery of heat applied to a
subsurface formation, comprising: (a) heating a first heater
pattern in the subsurface formation using a heater; (b) determining
an expected electrical conductivity of the first heater pattern;
(c) calculating an estimated electrical conductivity; (d) comparing
an estimated electrical conductivity of the first heater pattern to
the expected electrical conductivity until the estimated electrical
conductivity equals the expected electrical conductivity; (e)
determining a first heater pattern reaction extent of the first
heater pattern when the estimated electrical conductivity equals
the expected electrical conductivity; and (f) when the first heater
pattern reaction extent is within a target coke first heater
pattern reaction extent range, one of (i) heating a second heater
pattern instead of the first heater pattern and (ii) modifying the
heating of the first heater pattern, and when the first heater
pattern reaction extent is outside of the target coke first heater
pattern reaction extent range repeating steps (a)-(e).
2. The method of claim 2, wherein determining the expected
electrical conductivity comprises using electrical resistive
tomography.
3. The method of claim 2, wherein calculating the estimated
electrical conductivity comprises determining how an experimental
electrical conductivity changes as a function of an experimental
coke heater pattern reaction extent and an experimental
temperature.
4. The method of claim 3, wherein determining how the experimental
electrical conductivity changes comprises using a functional
relationship equal to:
.sigma.=A(.epsilon..sub.coke)e.sup.B(.epsilon..sup.coke.sup.)T
where .sigma. is the experimental electrical conductivity, A is a
first functional characteristic, .epsilon..sub.coke is the
experimental coke heater pattern reaction extent, e is an
exponential function, B is a second functional characteristic, T is
the experimental temperature, A(.epsilon..sub.coke) is that the
first functional relationship is a function of the coke heater
pattern reaction extent and B(.epsilon..sub.coke) is that the
second functional relationship is a function of the coke heater
pattern reaction extent.
5. The method of claim 3, wherein calculating the estimated
electrical conductivity further comprises calculating a first
functional characteristic and a second functional
characteristic.
6. The method of claim 5, wherein calculating the first functional
characteristic and the second functional characteristic comprises
regressing a plot of the experimental electrical conductivity
versus the experimental temperature.
7. The method of claim 6, wherein calculating the estimated
electrical conductivity comprises using the functional
relationship, the first functional characteristic, the second
functional characteristic, and one of an estimated temperature and
an estimated first heater pattern reaction extent.
8. A method for producing hydrocarbons from a subsurface formation
while controlling delivery of heat applied to the subsurface
formation, comprising: (a) heating a first heater pattern in the
subsurface formation using a heater; (b) determining an expected
electrical conductivity of the first heater pattern; (c)
calculating an estimated electrical conductivity; (d) comparing an
estimated electrical conductivity of the first heater pattern to
the expected electrical conductivity until the estimated electrical
conductivity equals the expected electrical conductivity; (e)
determining a first heater pattern reaction extent of the first
heater pattern when the estimated electrical conductivity equals
the expected electrical conductivity; (f) when the first heater
pattern reaction extent is within a target coke first heater
pattern reaction extent range, one of (i) heating a second heater
pattern instead of the first heater pattern and (ii) modifying the
heating of the first heater pattern, and when the first heater
pattern reaction extent is outside of the target coke first heater
pattern reaction extent range repeating steps (a)-(e) (g)
mobilizing the hydrocarbons from at least one of the first heater
pattern and the second heater pattern by heating the hydrocarbons;
and (h) producing the hydrocarbons.
9. The method of claim 8, wherein the heater comprises heaters.
10. The method of claim 8, wherein determining the expected
electrical conductivity comprises using electrical resistive
tomography.
11. The method of claim 8, wherein calculating the estimated
electrical conductivity comprises determining how an experimental
electrical conductivity changes as a function of an experimental
coke heater pattern reaction extent and an experimental
temperature.
12. The method of claim 8, wherein (g) and (h) occur when (f)
occurs.
13. The method of claim 8, wherein (g) and (h) occur after (f)
occurs.
14. The method of claim 11, wherein determining how the
experimental electrical conductivity changes comprises using a
functional relationship equal to:
.sigma.=A(.epsilon..sub.coke)e.sup.B(.epsilon..sup.coke.sup.)T
where .sigma. is the experimental electrical conductivity, A is a
first functional characteristic, .epsilon..sub.coke is the
experimental coke heater pattern reaction extent, e is an
exponential function, B is a second functional characteristic, T is
the experimental temperature, A(.epsilon..sub.coke) is that the
first functional relationship is a function of the coke heater
pattern reaction extent and B(.epsilon..sub.coke) is that the
second functional relationship is a function of the coke heater
pattern reaction extent.
15. The method of claim 11, wherein calculating the estimated
electrical conductivity further comprises calculating a first
functional characteristic and a second functional
characteristic.
16. The method of claim 15, wherein calculating the first
functional characteristic and the second functional characteristic
comprises regressing a plot of the experimental electrical
conductivity versus the experimental temperature.
17. The method of claim 16, wherein calculating the estimated
electrical conductivity comprises using the functional
relationship, the first functional characteristic, the second
functional characteristic, and one of an estimated temperature and
an estimated first heater pattern reaction extent.
18. The method of claim 16, wherein (g) and (h) occur when (f)
occurs.
19. The method of claim 16, wherein (g) and (h) occur after (f)
occurs.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is the National Stage entry under 35 U.S.C.
371 of PCT/US2015/028272 that published as WO 2016/018480 and was
filed on 29 Apr. 2015, which claims the priority benefit of U.S.
Provisional Patent Application 62/031,093 filed 30 Jul. 2014
entitled CONTROLLED DELIVERY OF HEAT APPLIED TO A SUBSURFACE
FORMATION, the entirety of which is incorporated by reference
herein.
BACKGROUND
[0002] Fields of Disclosure
[0003] The disclosure relates generally to the field of hydrocarbon
recovery from subsurface formations and, more particularly, to
controlling delivery of heat applied to a subsurface formation.
[0004] Description of Related Art
[0005] This section is intended to introduce various aspects of the
art, which may be associated with the present disclosure. This
discussion is believed to assist in providing a framework to
facilitate a better understanding of particular aspects of the
present disclosure. Accordingly, it should be understood that this
section should be read in this light, and not necessarily as
admissions of prior art.
[0006] Modern society is greatly dependent on the use of
hydrocarbons for fuels and chemical feedstocks. Subterranean
formations that can be termed "reservoirs" may contain resources,
such as hydrocarbons, that can be recovered. Removing hydrocarbons
from the subterranean reservoirs depends on numerous physical
properties of the subterranean rock formations, such as the
permeability of the rock containing the hydrocarbons, the ability
of the hydrocarbons to flow through the subterranean rock
formations, and the proportion of hydrocarbons present, among other
things.
[0007] Easily produced sources of hydrocarbons are dwindling,
resulting in increased reliance on less conventional sources (i.e.,
unconventional resources) to satisfy future needs. Examples of
unconventional resources may include but are not limited to heavy
oil, tar and oil shale. The unconventional resources may be found
in subsurface formations. For example, oil shale may be found in a
subsurface formation referred to as an oil shale formation because
the subsurface formation contains oil shale. The world contains a
substantial amount of unconventional resources. For example, the
U.S. is estimated to contain over 4 billion barrels of oil (GBO)
in-place.
[0008] Despite the substantial amount of unconventional resources
in place, surface access to unconventional resources may be
difficult. In situ conversion techniques that apply heat to
unconventional resources offer the potential to access
unconventional resources. In situ conversion techniques that apply
heat to unconventional resources may be referred to as thermal
processes. In situ conversion techniques refer to methods of
producing and/or generating hydrocarbons from a subsurface
formation in the original location or position of an unconventional
resource.
[0009] Applying a thermal process to an unconventional resource may
thermally decompose the unconventional resource to form gas
hydrocarbons, liquid hydrocarbons and coke. For example, applying
heat to oil shale may thermally decompose kerogen within the oil
shale to form gas hydrocarbons, liquid hydrocarbons and coke.
Continued application of heat via a thermal process to coke may
cause the coke to undergo pyrolysis. Hydrogen and methane may be
produced when the coke undergoes pyrolysis. The production of the
hydrogen and methane may lead to a purified coke with a lower
hydrogen to carbon ratio than is present in the unconventional
resource before applying heat. The purified coke is coke that has
been substantially dehydrogenated.
[0010] Energy required to convert a specified volume of an
unconventional resource to a flowable hydrocarbon, when applying a
thermal process to an unconventional resource, is governed by rock
properties of the subsurface formation which contains the
unconventional resource. The advantageous affects of one in situ
conversion technique over another may be governed by how efficient
it is for an in situ conversion technique to deliver energy to the
subsurface formation containing the unconventional resource. Rock
properties of the subsurface formation may include properties of
the subsurface formation that can be measured and/or calculated.
Examples of rock properties include but are not limited to
electrical conductivity.
[0011] While applying heat to an unconventional resource, and as
shown in FIG. 1, an electrical conductivity of the unconventional
resource may increase by several orders of magnitude. FIG. 1 shows
that electrical conductivity of an unconventional resource may
increase by several orders of magnitude for three different heating
rates--a small heating rate 51, a moderate heating rate 52 and a
large heating rate 53. The heating rate refers to the increase in
the temperature that the unconventional resource experiences per
unit time. The increase in electrical conductivity by several
orders of magnitude may be due to the pyrolysis of the coke and the
subsequent substantial dehydrogenation of the coke. The electrical
conductivity may decrease after increasing by several orders of
magnitude. The electrical conductivity decreases when carbonate
minerals decompose and release carbon dioxide (CO.sub.2) that may
gasify coke.
[0012] The electrical conductivity of an unconventional resource,
while applying a thermal process to the unconventional resource, is
a function of temperature and a reaction extent of coke
(.epsilon..sub.coke)--interchangeably referred to as coke reaction
extent--that has been pyrolyzed (.epsilon..sub.coke) (FIG. 2). FIG.
2 shows the electrical conductivity 62 and temperature 61 of an oil
shale sample that was heated in cycles and held isothermal at
specific temperatures over time. FIG. 2 shows that when the oil
shale sample is heated from about 0 hours to about 8 hours, the
electrical conductivity of the oil shale changes because the
temperature and the reaction extent change. In other words, from
about 0 hours to about 8 hours, the electrical conductivity is
temperature dependent and reaction extent dependent. FIG. 2 shows
that from about 8 hours to about 24 hours, even though the reaction
extent remains the same, the electrical conductivity changes
because the temperature changes. In other words, FIG. 2 shows that
from about 8 hours to about 24 hours, the electrical conductivity
is temperature dependent. FIG. 2 shows that from about 24 hours to
about 34 hours, even though the temperature remains the same, the
electrical conductivity changes because the reaction extent
changes. In other words, FIG. 2 shows that from about 24 hours to
about 34 hours, the electrical conductivity is reaction extent
dependent.
[0013] While it is known that the electrical conductivity of some
unconventional resources, while applying a thermal process to these
unconventional resource, is a function of temperature and a
reaction extent of coke that has been pyrolyzed, it is not known
how to interpret the data for electrical conductivity of these
unconventional resources as a function of temperature and reaction
extent of coke that has been pyrolyzed; it is also not know how to
trigger heating or cooling strategies of the unconventional
resource based on the properties of the subsurface formation.
[0014] A need exists for improved technology, including technology
that may address one or more of the above described disadvantages.
For example, a need exists for controlling delivery of heat applied
to a subsurface formation during a thermal process. Controlling the
delivery of heat applied to the subsurface formation during a
thermal process may be aided by the ability to interpret the data
for electrical conductivity of an unconventional resources as a
function of temperature and reaction extent of coke that has been
pyrolyzed. Controlling the delivery of heat applied to the
subsurface formation during a thermal process may be aided by
knowing how to trigger heating or cooling strategies of an
unconventional resource based on properties of the subsurface
formation.
SUMMARY
[0015] The present disclosure may provide a method for controlling
delivery of heat to a subsurface formation. The method may comprise
(a) heating a first heater pattern in the subsurface formation
using a heater; (b) determining an expected electrical conductivity
of the first heater pattern; (c) calculating an estimated
electrical conductivity; (d) comparing an estimated electrical
conductivity of the first heater pattern to the expected electrical
conductivity until the estimated electrical conductivity equals the
expected electrical conductivity; (e) determining a first heater
pattern reaction extent of the first heater pattern when the
estimated electrical conductivity equals the expected electrical
conductivity; and (f) when the first heater pattern reaction extent
is within a target coke first heater pattern reaction extent range,
one of (i) heating a second heater pattern instead of the first
heater pattern and (ii) modifying the heating of the first heater
pattern, and when the first heater pattern reaction extent is
outside of the target coke first heater pattern reaction extent
range repeating steps (a)-(e).
[0016] The present disclosure may provide a method for producing
hydrocarbons from a subsurface formation while controlling delivery
of heat to the subsurface formation. The method may comprise (a)
heating a first heater pattern in the subsurface formation using a
heater; (b) determining an expected electrical conductivity of the
first heater pattern; (c) calculating an estimated electrical
conductivity; (d) comparing an estimated electrical conductivity of
the first heater pattern to the expected electrical conductivity
until the estimated electrical conductivity equals the expected
electrical conductivity; (e) determining a first heater pattern
reaction extent of the first heater pattern when the estimated
electrical conductivity equals the expected electrical
conductivity; and (f) when the first heater pattern reaction extent
is within a target coke first heater pattern reaction extent range,
one of (i) heating a second heater pattern instead of the first
heater pattern and (ii) modifying the heating of the first heater
pattern, and when the first heater pattern reaction extent is
outside of the target coke first heater pattern reaction extent
range repeating steps (a)-(e); (g) mobilizing the hydrocarbons from
at least one of the first heater pattern and the second heater
pattern by heating the hydrocarbons; and (h) producing the
hydrocarbons.
[0017] The foregoing has broadly outlined the features of the
present disclosure so that the detailed description that follows
may be better understood. Additional features will also be
described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] These and other features, aspects and advantages of the
present disclosure will become apparent from the following
description and the accompanying drawings, which are described
briefly below.
[0019] FIG. 1 is a diagram of electrical conductivity trends.
[0020] FIG. 2 is a diagram of oil shale temperature and electrical
conductivity trends.
[0021] FIG. 3 is a diagram showing electrical conductivity as a
function of temperature for specific coke reaction extent.
[0022] FIG. 4A is a map of electrical conductivity within a
subsurface formation.
[0023] FIG. 4B is a map of electrical conductivity within a
subsurface formation.
[0024] FIG. 5 is a front view of a subsurface formation.
[0025] FIG. 6 is a schematic of methods of the present
disclosure.
[0026] It should be noted that the figures are merely examples and
that no limitations on the scope of the present disclosure are
intended hereby. Further, the figures are generally not drawn to
scale but are drafted for the purpose of convenience and clarity in
illustrating various aspects of the disclosure.
DETAILED DESCRIPTION
[0027] For the purpose of promoting an understanding of the
principles of the disclosure, reference will now be made to the
features illustrated in the drawings and specific language will be
used to describe the same. It will nevertheless be understood that
no limitation of the scope of the disclosure is thereby intended.
Any alterations and further modifications, and any further
applications of the principles of the disclosure as described
herein are contemplated as would normally occur to one skilled in
the art to which the disclosure relates. It will be apparent to
those skilled in the relevant art that some features that are
relevant to the present disclosure may not be shown in the drawings
for the sake of clarity.
[0028] At the outset, for ease of reference, certain terms used in
this application and their meaning as used in this context are set
forth below. To the extent a term used herein is not defined below,
it should be given the broadest definition persons in the pertinent
art have given that term as reflected in at least one printed
publication or issued patent. Further, the present processes are
not limited by the usage of the terms shown below, as all
equivalents, synonyms, new developments and terms or processes that
serve the same or a similar purpose are considered to be within the
scope of the present disclosure.
[0029] As used herein, the term "electrical conductivity" refers to
the ability of a material to conduct electricity. Electrical
conductivity is the inverse of resistivity. The electrical
conductivity is a property of a material.
[0030] As used herein, the term "hydrocarbon" refers to an organic
compound that includes primarily, if not exclusively, the elements
hydrogen and carbon. Hydrocarbons may also include other elements,
such as, but not limited to, halogens, metallic elements, nitrogen,
oxygen, and/or sulfur. Hydrocarbons generally fall into two
classes: aliphatic, or straight chain hydrocarbons, and cyclic, or
closed ring hydrocarbons, including cyclic terpenes. Examples of
hydrocarbon-containing materials include any form of natural gas,
oil, coal, heavy oil and kerogen that can be used as a fuel or
upgraded into a fuel.
[0031] As used herein, the terms "produced fluids" and "production
fluids" refer to liquids and/or gases removed from a subsurface
formation, including, for example, an organic-rich rock formation.
Produced fluids may include both hydrocarbon fluids and
non-hydrocarbon fluids. Production fluids may include, but are not
limited to, liquids and/or gases originating from pyrolysis of oil
shale, natural gas, synthesis gas, a pyrolysis product of coal,
carbon dioxide, hydrogen sulfide and water (including steam).
[0032] As used herein, the term "fluid" refers to gases, liquids,
and combinations of gases and liquids, as well as to combinations
of gases and solids, and combinations of liquids and solids.
[0033] As used herein, the term "formation hydrocarbons" refers to
both light and/or heavy hydrocarbons and solid hydrocarbons that
are contained in an organic-rich rock formation. Formation
hydrocarbons may be, but are not limited to, natural gas, oil,
kerogen, oil shale, coal, tar, natural mineral waxes, and
asphaltenes.
[0034] As used herein, the term "gas" refers to a fluid that is in
its vapor phase at 1 atmosphere (atm) and 15 degrees Celsius
(.degree. C.).
[0035] As used herein, the term "kerogen" refers to a solid,
insoluble hydrocarbon that may principally contain carbon,
hydrogen, nitrogen, oxygen, and/or sulfur.
[0036] As used herein, the term "oil" refers to a hydrocarbon fluid
containing primarily a mixture of condensable hydrocarbons.
[0037] As used herein, the term "oil shale" refers to any
fine-grained, compact, sedimentary rock containing organic matter
made up mostly of kerogen, a high-molecular weight solid or
semi-solid substance that is insoluble in petroleum solvents and is
essentially immobile in its rock matrix.
[0038] As used herein, the term "organic-rich rock" refers to any
rock matrix holding solid hydrocarbons and/or heavy hydrocarbons.
Rock matrices may include, but are not limited to, sedimentary
rocks, shales, siltstones, sands, silicilytes, carbonates, and
diatomites. Organic-rich rock may contain kerogen.
[0039] As used herein, the term "organic-rich rock formation"
refers to any formation containing organic-rich rock. Organic-rich
rock formations include, for example, oil shale formations, coal
formations, tar sands formations or other formation
hydrocarbons.
[0040] As used herein, "overburden" refers to the material
overlying a subterranean reservoir. The overburden may include
rock, soil, sandstone, shale, mudstone, carbonate and/or ecosystem
above the subterranean reservoir. During surface mining the
overburden is removed prior to the start of mining operations. The
overburden may refer to formations above or below free water level.
The overburden may include zones that are water saturated, such as
fresh or saline aquifers. The overburden may include zones that are
hydrocarbon bearing.
[0041] As used herein, "permeability" is the capacity of a rock to
transmit fluids through the interconnected pore spaces of the
structure. A customary unit of measurement for permeability is the
milliDarcy (mD). The term "absolute permeability" is a measure for
transport of a specific, single-phase fluid through a specific
portion of a formation. The term "relative permeability" is defined
for relative flow capacity when one or more fluids or one or more
fluid phases may be present within the pore spaces, in which the
interference between the different fluid types or phases competes
for transport within the pore spaces within the formation. The
different fluids present within the pore spaces of the rock may
include water, oil and gases of various compositions. Fluid phases
may be differentiated as immiscible fluids, partially miscible
fluids and vapors. The term "low permeability" is defined, with
respect to subsurface formations or portions of subsurface
formations, as an average permeability of less than about 10
mD.
[0042] As used herein, the term "pyrolysis" or "pyrolyze" refers to
the breaking of chemical bonds through the application of heat. For
example, pyrolysis may include transforming a compound into one or
more other substances by heat alone or by heat in combination with
an oxidant. Pyrolysis may include modifying the nature of the
compound by addition of hydrogen atoms which may be obtained from
molecular hydrogen, water, carbon dioxide, or carbon monoxide. Heat
may be transferred to a section of the formation to cause
pyrolysis.
[0043] As used herein, the term "reaction extent" refers to how far
along a reaction has progressed for a given reaction or a given set
of reactions.
[0044] As used herein, "reservoir" or "subterranean reservoir" is a
subsurface rock or sand formation from which a production fluid or
resource can be harvested. The rock formation may include sand,
granite, silica, carbonates, clays, and organic matter, such as oil
shale, light or heavy oil, gas, or coal, among others. Reservoirs
can vary in thickness from less than one foot (0.3048 meter (m)) to
hundreds of feet (hundreds of meters).
[0045] As used herein, the term "solid hydrocarbons" refers to any
hydrocarbon material that is found naturally in substantially solid
form at formation conditions. Non-limiting examples include
kerogen, coal, shungites, asphaltites, and natural mineral
waxes.
[0046] As used herein "subsurface formation" or "subterranean
formation" refers to the material existing below the Earth's
surface. The subsurface formation may interchangeably be referred
to as a formation or a subterranean formation. The subsurface
formation may comprise a range of components, e.g. minerals such as
quartz, siliceous materials such as sand and clays, as well as the
oil and/or gas that is extracted.
[0047] As used herein, "substantial," "about" and "approximate"
when used in reference to a quantity or amount of a material, or a
specific characteristic of the material, refers to an amount that
is sufficient to provide an effect that the material or
characteristic was intended to provide. The exact degree of
deviation allowable may in some cases depend on the specific
context.
[0048] As used herein, the term "tar" refers to a viscous
hydrocarbon that generally has a viscosity greater than about
10,000 centipoise (cP) at 15.degree. C. The specific gravity of tar
generally is greater than 1.000. Tar may have an American Petroleum
Institute (API) gravity less than 10 degrees. "Tar sands" refers to
a formation that has tar in it. In contrast, light oil may have a
viscosity less than 10 cP; medium oil and heavy oil may have a
viscosity of 10 cP and greater, up to or exceeding 10,000 cP.
[0049] As used herein, "underburden" refers to the material
underlaying a subterranean reservoir. The underburden may include
rock, soil, sandstone, shale, mudstone, wet/tight carbonate and/or
ecosystem below the subterranean reservoir.
[0050] As used herein, "wellbore" is a hole in the subsurface
formation made by drilling or inserting a conduit into the
subsurface. A wellbore may have a substantially circular cross
section or any other cross-section shape, such as an oval, a
square, a rectangle, a triangle, or other regular or irregular
shapes. The term "well," when referring to an opening in the
formation, may be used interchangeably with the term "wellbore."
Further, multiple pipes may be inserted into a single wellbore, for
example, as a liner configured to allow flow from an outer chamber
to an inner chamber.
[0051] As used herein, the term "coupled" means the joining of two
members directly or indirectly to one another. Such joining may be
stationary or moveable in nature. Such joining may be achieved with
the two members or the two members and any additional intermediate
members being integrally formed as a single unitary body with one
another or with the two members or the two members and any
additional intermediate members being attached to one another. Such
joining may be permanent in nature or may be removable or
releasable in nature.
[0052] The articles "the", "a" and "an" are not necessarily limited
to mean only one, but rather are inclusive and open ended so as to
include, optionally, multiple such elements.
[0053] "At least one," in reference to a list of one or more
entities should be understood to mean at least one entity selected
from any one or more of the entity in the list of entities, but not
necessarily including at least one of each and every entity
specifically listed within the list of entities and not excluding
any combinations of entities in the list of entities. This
definition also allows that entities may optionally be present
other than the entities specifically identified within the list of
entities to which the phrase "at least one" refers, whether related
or unrelated to those entities specifically identified. Thus, as a
non-limiting example, "at least one of A and B" (or, equivalently,
"at least one of A or B," or, equivalently "at least one of A
and/or B") may refer, to at least one, optionally including more
than one, A, with no B present (and optionally including entities
other than B); to at least one, optionally including more than one,
B, with no A present (and optionally including entities other than
A); to at least one, optionally including more than one, A, and at
least one, optionally including more than one, B (and optionally
including other entities). In other words, the phrases "at least
one," "one or more," and "and/or" are open-ended expressions that
are both conjunctive and disjunctive in operation. For example,
each of the expressions "at least one of A, B and C," "at least one
of A, B, or C," "one or more of A, B, and C," "one or more of A, B,
or C" and "A, B, and/or C" may mean A alone, B alone, C alone, A
and B together, A and C together, B and C together, A, B and C
together, and optionally any of the above in combination with at
least one other entity.
[0054] The disclosure relates to systems and methods for
controlling delivery of heat applied to a subsurface formation.
FIGS. 1-6 of the disclosure display various aspects of the systems
and methods.
[0055] The systems 10 and methods 100 may include heating a first
heater pattern 31 in a subsurface formation 15 using a heater 30,
101 (FIGS. 5-6). The subsurface formation 15 may comprise an
overburden 28, a subterranean reservoir 16, and an underburden 27.
The hydrocarbons may be within the subterranean reservoir 16. The
top of the subsurface formation 15 may be a surface 12. The surface
may be the Earth's surface.
[0056] The heater 30 may heat hydrocarbons within the subsurface
formation 15. The hydrocarbons may be referred to as formation
hydrocarbons. The heater 30 may heat hydrocarbons within the
subterranean reservoir 16 of the subterranean formation 15. The
heater 30 may heat the hydrocarbons by generating heat. The heater
30 may generate heat when power transmitted to the heater 30
reaches the heater 30. The power may be transmitted in any suitable
way. The power transmitted may be defined as any component of
energy, such as but not limited to magnitude or frequency. The
heater 30 may conduct electricity. The heater 30 may have an
electrical conductivity.
[0057] The heater 30 may comprise heaters. Each of the heaters 30
may require power to generate heat. The heaters 30 may be
controlled as a system or independently. One or more of the heaters
30 may be within the first heater pattern 31. The first heater
pattern 31 may be the area that the one or more heaters 30 within
the first heater pattern heat. The first heater pattern 31 may span
any area within the subsurface formation 15. The first heater
pattern 31 may form any shape within the subsurface formation
15.
[0058] The subsurface formation may include a second heater pattern
32. The second heater pattern 32 may include one or more heaters
30. The second heater pattern 32 may be separate and distinct from
the first heater pattern 31. If the second heater pattern 32 is
separate from the first heater pattern 31, the one or more heaters
30 within the second heater pattern 32 may be separate from the one
or more heaters 30 within the first heater pattern 31. As shown in
FIG. 5, for example, the first heater pattern 31 is separate from
the second heater pattern 32 and the first heater pattern 31
includes one of the heaters 30 while the second heater pattern 32
includes another of the heaters 30; the first heater pattern 31 is
adjacent to the second heater pattern 32 but spaced apart from the
second heater pattern 32. The second heater pattern 32 may abut the
first heater pattern 31. The second heater pattern 32 may overlap
at least a portion of the first heater pattern 31. If the second
heater pattern 32 overlaps at least the portion of the first heater
pattern 31, at least a portion of the one or more heaters 30 within
the second heater pattern 32 may be within the first heater pattern
31. The second heater pattern 32 may span any area within the
subsurface formation 15. The second heater pattern 32 may form any
shape within the subsurface formation 15.
[0059] The systems 10 and methods 100 may include determining an
expected electrical conductivity of the first heater pattern 31,
102 (FIG. 6). The expected electrical conductivity of the first
heater pattern 31 may be determined by any suitable method. For
example, the expected electrical conductivity of the first heater
pattern 31 may be determined using electrical resistive tomography
(ERT). ERT is a method to spatially map a resistivity volume of a
component by applying a known current to a first electrode in
contact with a formation of interest and by measuring the induced
voltage potential between second electrodes in contact with the
formation of interest. The component may be the heater 30, a
wellbore not used for heating, a production wellbore or an
observation wellbore. An observation wellbore may be a wellbore
used to observe what occurs in the subsurface formation 15. An
observation wellbore may not heat or produce hydrocarbons. An
observation wellbore may measure data within the subsurface
formation 15. The formation of interest may be any or all of the
subsurface formation 15 (e.g., the subsurface reservoir 16, the
subsurface reservoir 16 and the overburden 28, the subsurface
reservoir 16 and the underburden 27). If the formation of interest
is the subsurface formation 15, the first electrode may be in
contact with the formation of interest. If the formation of
interest is the subsurface formation 15, the second electrodes may
be in contact with the formation of interest. The mathematical
basis for ERT is based on Poisson's equation:
-.gradient.(.sigma..gradient..phi.)=0 (1).
Poisson's equation may be solved in a piecewise continuous fashion
for the formation of interest. In equation (1), .sigma. is the
electrical conductivity, .phi. is the voltage potential and
.gradient. is the Laplace operator. The solution to equation (1)
may be subject to the following boundary condition:
.sigma..sub.sn.gradient..phi.=J.sub.s (2).
In equation (2), n is a unit normal vector defining a face of the
control volume and J.sub.s is a density at a surface of each
control volume. Equation (2) depicts that the current density at
the surface of each control volume J.sub.s is proportional to a
voltage potential gradient across the control volume and the
electrical conductivity of the control volume. Using multiple
measurements of .phi. and J it is possible to determine spatially
the formation of interest's electrical conductivity. The control
volume is an infinitesimally small portion of the formation of
interest. The control volume is a way to mathematically descritize
the entire formation of interest" so that electrical conductivity
can be solved for at each descrete control volume within the
formation of interest.
[0060] Conventional technology has used ERT. But the conventional
technology has failed to recognize that substantial changes to the
electrical conductivity of a subsurface formation may be associated
with chemical reactions attributable to hydrocarbon conversion.
Conventional technology has failed to identify how to interpret ERT
data for reaction extent and how specific values trigger specific
responses.
[0061] While the above discussion focuses on how to determine an
expected electrical conductivity of the first heater pattern 31, an
expected electrical conductivity of the second heater pattern 32
may be determined by any of the methods that can be used to
determine the expected electrical conductivity of the first heater
pattern 31. If the subsurface formation 15 contains more than the
first heater pattern 31 and the second heater pattern 32 (e.g., a
third heater pattern, a fourth heater pattern), each of the other
heater patterns (e.g., a third heater pattern, a fourth heater
pattern) may be determined by any of the methods that can be used
to determine the expected electrical conductivity of the first
heater pattern 31 and/or the second heater pattern 32.
[0062] The systems 10 and methods 100 may include calculating an
estimated electrical conductivity, 103 (FIG. 4). Calculating the
estimated electrical conductivity may comprise determining how an
experimental electrical conductivity changes as a function of an
experimental coke heater pattern reaction extent and an
experimental temperature. Determining how the experimental
electrical conductivity changes may comprise using a functional
relationship.
[0063] The functional relationship has been conventionally thought
to be equal to the following equation:
.sigma.=Ae.sup.BT (3)
In equation (3), A is a first functional relationship, B is a
second functional relationship, e is an exponential function, T is
temperature and .sigma. is electrical conductivity. Using equation
(3) to calculate the estimated electrical conductivity does not
yield a correctly calculated estimated electrical conductivity for
a subterranean formation that is governed by the characteristics
shown in FIG. 2. Namely, using equation (3) to calculate the
estimate electrical conductivity does not yield a correctly
calculated estimated electrical conductivity for a subterranean
formation whose electrical conductivity is a function of
temperature and reaction extent of coke. The present inventors
determined that equation (3) yields an incorrectly estimate
electrical conductivity for a subterranean formation, which is
governed by the characteristics shown in FIG. 2, because equation
(3) does not enable the decoupling of electrical conductivity's
dependence on temperature from the reaction extent of coke.
[0064] The present inventors determined that the functional
relationship having the following equation correctly estimates
electrical conductivity for a subterranean formation governed by
the characteristics shown in FIG. 2:
.sigma.=A(.epsilon..sub.coke)e.sup.B(.epsilon..sup.coke.sup.)T
(4)
In equation (4), A is a first functional relationship, B is a
second functional relationship, e is an exponential function, T is
temperature, .sigma. is electrical conductivity, .epsilon..sub.coke
is a coke heater pattern reaction extent, A(.epsilon..sub.coke) is
that the first functional relationship is a function of the coke
heater pattern reaction extent and B(.epsilon..sub.coke) is that
the second functional relationship is a function of the coke heater
pattern reaction extent. The first functional relationship is a
constant obtained from experimentation. The second functional
relationship is a constant obtained from experimentation. The
temperature may be referred to as an experimental temperature. The
electrical conductivity may be referred to as an estimated
electrical conductivity. The coke heater pattern reaction extent
may be referred to as an experimental coke heater pattern reaction
extent.
[0065] The functional relationship shown in equation (4) may be
determined by conducting experiments at a constant experimental
reaction extent or a constant experimental temperature such that
the effects of the experimental temperature and the experimental
reaction extent on the experimental electrical conductivity can be
decoupled. When conducting experiments at a constant experimental
reaction extent, the experimental electrical conductivity changes
as a function of the experimental temperature for the constant
experimental reaction extent. For example, as shown in FIG. 3, the
experimental electrical conductivity changes as a function of the
experimental temperature for six different experimental reaction
extents. The six experimental reaction extents are held constant.
Each of the six experimental reaction extents is a different
experimental reaction extent numerical value from the other five
experimental reaction extents. When the experimental reaction
extents are held constant, the experimental temperature changes.
The changing experimental temperature for the six experimental
reaction extents is shown by line 71, line 72, line 73, line 79,
line 75 and line 76. When conducting experiments at a constant
experimental temperature, the experimental electrical conductivity
changes as a function of the experimental reaction extent for the
constant experimental temperature. When an experimental temperature
is held constant, the experimental reaction extent will change. If
the experimental reaction extent and the experimental temperature
are not held constant, as shown via line 78 in FIG. 3, the effects
of experimental temperature and experimental reaction extent on
experimental electrical conductivity cannot be decoupled.
[0066] Calculating the estimated electrical conductivity may
comprise calculating the first functional relationship and the
second functional relationship. The first functional relationship
and the second functional relationship may be obtained by
regression. The regression may comprise linear regression. If
experiments are conducted with constant experimental reaction
extents, as shown in FIG. 3, the first functional relationship and
the second functional relationship may be obtained by regressing a
plot, such as that of FIG. 3, that shows the experimental
electrical conductivities for constant experimental reaction
extents and varying experimental temperatures. If the experiments
are conducted with constant experimental temperatures, the first
functional relationship and the second functional relationship may
be obtained by regressing the plot showing the experimental
electrical conductivities for constant experimental temperatures
and varying experimental reaction extents.
[0067] Calculating the estimated electrical conductivity may
comprise using the functional relationship depicted in equation
(4), the first functional characteristic, the second functional
characteristic and one of an estimated temperature and an estimated
first heater pattern reaction extent. Specifically, calculating the
estimated electrical conductivity may comprise inputting the first
functional characteristic, the second functional characteristic and
one of the estimated temperature and the estimated first heater
pattern reaction extent into the functional relationship depicted
in equation (4) to calculate the estimate electrical conductivity.
The estimated temperature may be any temperature value. The
estimated first heater pattern reaction extent may be any reaction
extent. The estimated temperature may be determined by an operator.
The first heater pattern reaction extent may be determined by an
operator. The operator may be a person or a mechanism for
performing operations.
[0068] The systems 10 and methods 100 may comprise comparing the
estimated electrical conductivity of the first heater pattern 31 to
the expected electrical conductivity of the first heater pattern 31
until the estimated electrical conductivity equals the expected
electrical conductivity, 104 (FIG. 4). When comparing the estimated
electrical conductivity to the expected electrical conductivity,
the estimated electrical conductivity may be calculated by
inputting the first functional characteristic, the second
functional characteristic and one of a first estimated temperature
and a first estimated first heater pattern reaction extent into the
functional relationship depicted in equation (4). The estimated
electrical conductivity that is calculated may be what is compared
to the expected electrical conductivity. If the calculated
estimated electrical conductivity equals the expected electrical
conductivity, there is no need to calculate another estimated
electrical conductivity. the estimated electrical conductivity does
not equal the expected electrical conductivity, another estimated
electrical conductivity may be calculated by inputting the first
functional characteristic, the second functional characteristic and
one of a second estimated temperature and a second estimated first
heater pattern reaction extent into the functional relationship
depicted in equation (4). If the estimated electrical conductivity
calculated using the one of the second estimated temperature and
the second estimated first heater pattern reaction extent equals
the expected electrical conductivity, there is no need to calculate
another estimated electrical conductivity. If the estimated
electrical conductivity calculated using the one of the second
estimated temperature and the second estimated first heater pattern
reaction extent does not equal the expected electrical
conductivity, another estimated electrical conductivity must be
calculated by inputting the first functional characteristic, the
second functional characteristic and one of a third estimated
temperature and a third estimated first heater pattern reaction
extent into the functional relationship depicted in equation (4).
This process of calculating an estimated electrical conductivity
and comparing it to the expected electrical conductivity may
continue until the estimated electrical conductivity equals the
expected electrical conductivity. The first estimated temperature,
the second estimated temperature and the third estimated
temperature may be different numerical values. In other words, the
first estimated temperature may be a different numerical
temperature from the second estimated temperature and the third
estimated temperature, etc. The first estimated heater pattern
reaction extent, the second estimated heater pattern reaction
extent and the third estimated heater pattern reaction extent may
be different numerical values. In other words, the first estimated
heater pattern reaction extent may be a different numerical
reaction extent from the second estimated heater pattern reaction
extent and the third estimated heater pattern reaction extent,
etc.
[0069] The systems 10 and methods 100 may include determining one
of a first heater pattern reaction extent and a first heater
pattern temperature of the first heater pattern 31 when the
estimated electrical conductivity equals the expected electrical
conductivity, 105 (FIG. 6). The first heater pattern reaction
extent may be the reaction extent of the first heater pattern 31
within the subterranean formation. The first heater pattern
temperature may be the temperature of the first heater pattern 31.
The first heater pattern reaction extent may be the estimated first
heater pattern reaction extent that allows the estimated electrical
conductivity to equal the expected electrical conductivity. The
first heater pattern temperature may be the estimated temperature
that allows the estimated electrical conductivity to equal the
expected electrical conductivity.
[0070] The systems 10 and methods 100 may include determining
whether the first heater pattern reaction extent is within a target
coke first heater pattern reaction extent range, 106 (FIG. 6). The
target coke first heater pattern reaction extent range may be a
range of reaction extents indicative of overheating of the first
heater pattern. Overheating of a heater pattern means that a
substantial portion of the heater pattern has reached a reaction
extent that is greater than zero.
[0071] When the first heater pattern reaction extent is within the
target coke first heater pattern reaction extent range, a second
heater pattern 32 may be heated instead of the first heater pattern
31 or the heating of the first heater pattern 31 may be modified.
The target coke first heater pattern reaction extent range is the
range of reaction extents that indicate a hydrocarbon has thermally
decomposed to form coke within the first heater pattern 31. The
first heater pattern reaction extent being within the target coke
first heater pattern reaction extent range may be indicative of the
overcooking--interchangeably referred to as overheating--of
hydrocarbons within the first heater pattern 31. The first heater
pattern reaction extent being within the target coke first heater
pattern reaction extent range may be indicative of the hydrocarbons
within the first heater pattern 31 almost being overheated by a
heater 30. Each heater pattern (e.g., the first heater pattern, the
second heater pattern) has a heater pattern reaction extent when it
is heated and a target coke heater pattern reaction extent range.
For example, the second heater pattern 32 when heated has a second
heater pattern reaction extent and a target coke second heater
pattern reaction extent range. The target coke heater pattern
reaction extent range for each of these heater patterns is the
range of reaction extents that indicate a hydrocarbon has thermally
decomposed to form coke within the specific heater pattern in
question.
[0072] When the first heater pattern reaction extent is outside of
the first coke heater pattern reaction extent range, the steps of
heating the first heater pattern 101, determining the expected
electrical conductivity of the first heater pattern 102,
calculating the estimated electrical conductivity 103, comparing
the estimated electrical conductivity to the expected electrical
conductivity 104 and determining the first heater pattern reaction
extent 105 may be repeated. Repeating steps 101, 102, 103, 104 and
105 may terminate when the first heater pattern reaction extent is
within the target coke first heater pattern reaction extent
range.
[0073] The methods 10 and systems 100 may include mobilizing
hydrocarbons from at least one of the first heater pattern 31 and
the second heater pattern 32 by heating with the heater 30. The
hydrocarbons within a heater pattern (e.g., the first heater
pattern, the second heater pattern) may be mobilized while the
hydrocarbons within the heater pattern are heated by a heater 30.
As the hydrocarbons are mobilized they may flow to a production
wellbore 14. Mobilizing the hydrocarbons may occur before, after or
when heating the second heater pattern 32 instead of the first
heater pattern 31. Mobilizing the hydrocarbons may occur before,
after or when modifying the heating of the first heater pattern
31.
[0074] The methods 10 and systems 100 may include producing the
hydrocarbons. Once produced, the hydrocarbons may be referred to as
produced fluids. The hydrocarbons may be produced via the
production wellbore 14. The hydrocarbons produced may be the
hydrocarbons that are mobilized from the at least one of the first
heater pattern 31 and the second heater pattern 32. The production
wellbore 14 may be any suitable wellbore that is constructed to
produce hydrocarbons. The hydrocarbons produced via the production
wellbore 14 may be processed in a surface facility 17. The
hydrocarbons may be processed in the surface facility 17 so that
the hydrocarbons can be sold. The hydrocarbons may travel from the
production wellbore 14 to the surface facility 17 via a pipeline 18
(FIG. 5). Producing the hydrocarbons may occur before, after or
when heating the second heater pattern 32 instead of the first
heater pattern 31. Producing the hydrocarbons may occur before,
after or when modifying the heating of the first heater pattern
31.
[0075] The methods and systems disclosed in the present disclosure
may be implemented for any heater pattern (e.g., a first heater
pattern, a second heater pattern, a third heater pattern).
[0076] As a result of the methods and systems disclosed in the
present disclosure, a subsurface formation may be heated better.
The subsurface formation may be heated better because the methods
and systems disclosed of the present disclosure help prevent
overheating of a heater pattern. FIG. 4A shows a tomography map of
what is measured to occur in the subsurface formation. FIG. 4B is a
translation of electrical conductivity to reaction extent. FIG. 4B
is intended to reflect what is occurring in FIG. 4A once the
estimated electrical conductivity equals the expected electrical
conductivity. FIGS. 4A and 4B show that the methods of the present
disclosure, for considering the affects of chemical reaction
kinetics on electrical conductivity more accurately predict
reaction extent within the subsurface formation.
[0077] It is important to note that the elements and steps depicted
in FIGS. 1-6 are provided for illustrative purposes only and a
particular step may not be required to perform the inventive
methodologies. The claims, and only the claims, define the
inventive system and methodologies.
[0078] The method and system may include the mechanism for
performing operations. The mechanism for performing operations may
be specially constructed for the required purposes, or it may
comprise a general-purpose computer selectively activated or
reconfigured by a computer program stored in the general-purpose
computer. Such a computer program may be stored in a
computer-readable medium. The computer-readable medium may include
any mechanism for storing or transmitting information in a form
readable by a machine (e.g., a computer). The computer-readable
(e.g., machine-readable) medium may include, but is not limited to,
a machine (e.g., a computer) readable storage medium (e.g., read
only memory ("ROM"), random access memory ("RAM"), magnetic disk
storage media, optical storage media, flash memory devices, etc.),
and a machine (e.g., computer) readable transmission medium
(electrical, optical, acoustical or other form of propagated
signals (e.g., carrier waves, infrared signals, digital signals,
etc.)). The computer-readable medium may be non-transitory.
[0079] As will be apparent to one of ordinary skill in the relevant
art, the modules, features, attributes, methodologies, and other
aspects of the present disclosure can be implemented as software,
hardware, firmware or any combination of the three. Of course,
wherever a component of the present disclosure is implemented as
software, the component can be implemented as a standalone program,
as part of a larger program, as a plurality of separate programs,
as a statically or dynamically linked library, as a kernel loadable
module, as a device driver, and/or in every and any other way known
now or in the future to those of skill in the art of computer
programming. The present disclosure is in no way limited to
implementation in any specific operating system or environment.
[0080] Disclosed aspects of the present disclosure may be used in
hydrocarbon management activities. "Hydrocarbon management" or
"managing hydrocarbons" may include hydrocarbon extraction,
hydrocarbon production, hydrocarbon exploration, identifying
potential hydrocarbon resources, identifying well locations,
determining well injection and/or extraction rates, identifying
reservoir connectivity, acquiring, disposing of and/or abandoning
hydrocarbon resources, reviewing prior hydrocarbon management
decisions, and any other hydrocarbon-related acts or activities.
The term "hydrocarbon management" may be used for the injection or
storage of hydrocarbons or CO.sub.2, for example the sequestration
of CO.sub.2, such as reservoir evaluation, development planning,
and reservoir management. The disclosed methodologies and
techniques may be used to extract hydrocarbons from a subsurface
region. Hydrocarbon extraction may be conducted to remove
hydrocarbons from the subsurface region, which may be accomplished
by drilling a well using oil drilling equipment. The equipment and
techniques used to drill a well and/or extract the hydrocarbons are
well known by those skilled in the relevant art. Other hydrocarbon
extraction activities and, more generally, other hydrocarbon
management activities, may be performed according to known
principles.
[0081] It should be noted that the orientation of various elements
may differ, and that such variations are intended to be encompassed
by the present disclosure. It is recognized that features of the
disclosure may be incorporated into other examples.
[0082] It should be understood that the preceding is merely a
detailed description of this disclosure and that numerous changes,
modifications, and alternatives can be made in accordance with the
disclosure here without departing from the scope of the disclosure.
The preceding description, therefore, is not meant to limit the
scope of the disclosure. Rather, the scope of the disclosure is to
be determined only by the appended claims and their equivalents. It
is also contemplated that structures and features embodied in the
present examples can be altered, rearranged, substituted, deleted,
duplicated, combined, or added to each other.
EMBODIMENTS
Embodiment 1
[0083] A method for controlling delivery of heat applied to a
subsurface formation, comprising:
[0084] (a) heating a first heater pattern in the subsurface
formation using a heater;
[0085] (b) determining an expected electrical conductivity of the
first heater pattern;
[0086] (c) calculating an estimated electrical conductivity;
[0087] (d) comparing an estimated electrical conductivity of the
first heater pattern to the expected electrical conductivity until
the estimated electrical conductivity equals the expected
electrical conductivity;
[0088] (e) determining a first heater pattern reaction extent of
the first heater pattern when the estimated electrical conductivity
equals the expected electrical conductivity; and
[0089] (f) when the first heater pattern reaction extent is within
a target coke first heater pattern reaction extent range, one of
(i) heating a second heater pattern instead of the first heater
pattern and (ii) modifying the heating of the first heater pattern,
and
[0090] when the first heater pattern reaction extent is outside of
the target coke first heater pattern reaction extent range
repeating steps (a)-(e).
Embodiment 2
[0091] A method for producing hydrocarbons from a subsurface
formation while controlling delivery of heat applied to the
subsurface formation, comprising:
[0092] (a) heating a first heater pattern in the subsurface
formation using a heater;
[0093] (b) determining an expected electrical conductivity of the
first heater pattern;
[0094] (c) calculating an estimated electrical conductivity;
[0095] (d) comparing an estimated electrical conductivity of the
first heater pattern to the expected electrical conductivity until
the estimated electrical conductivity equals the expected
electrical conductivity;
[0096] (e) determining a first heater pattern reaction extent of
the first heater pattern when the estimated electrical conductivity
equals the expected electrical conductivity;
[0097] (f) when the first heater pattern reaction extent is within
a target coke first heater pattern reaction extent range, one of
(i) heating a second heater pattern instead of the first heater
pattern and (ii) modifying the heating of the first heater pattern,
and
[0098] when the first heater pattern reaction extent is outside of
the target coke first heater pattern reaction extent range
repeating steps (a)-(e)
[0099] (g) mobilizing the hydrocarbons from at least one of the
first heater pattern and the second heater pattern by heating the
hydrocarbons; and
[0100] (h) producing the hydrocarbons.
Embodiment 3
[0101] The method of embodiment 2, wherein the heater comprises
heaters.
Embodiment 4
[0102] The method of any one of embodiments 2-3, wherein
determining the expected electrical conductivity comprises using
electrical resistive tomography.
Embodiment 5
[0103] The method of any one of embodiments 2-4, wherein
calculating the estimated electrical conductivity comprises
determining how an experimental electrical conductivity changes as
a function of an experimental coke heater pattern reaction extent
and an experimental temperature.
Embodiment 6
[0104] The method of embodiment 5, wherein determining how the
experimental electrical conductivity changes comprises using a
functional relationship equal to:
.sigma.=A(.epsilon..sub.coke)e.sup.B(.epsilon..sup.coke.sup.)T
[0105] where .sigma. is the experimental electrical conductivity, A
is a first functional characteristic, .epsilon..sub.coke is the
experimental coke heater pattern reaction extent, e is an
exponential function, B is a second functional characteristic, T is
the experimental temperature, A(.epsilon..sub.coke) is that the
first functional relationship is a function of the coke heater
pattern reaction extent and B(.epsilon..sub.coke) is that the
second functional relationship is a function of the coke heater
pattern reaction extent.
Embodiment 7
[0106] The method of any one of embodiments 5-6, wherein
calculating the estimated electrical conductivity further comprises
calculating a first functional characteristic and a second
functional characteristic.
Embodiment 8
[0107] The method of embodiment 7, wherein calculating the first
functional characteristic and the second functional characteristic
comprises regressing a plot of the experimental electrical
conductivity versus the experimental temperature.
Embodiment 9
[0108] The method of claim any one of embodiments 6-8, wherein
calculating the estimated electrical conductivity comprises using
the functional relationship, the first functional characteristic,
the second functional characteristic, and one of an estimated
temperature and an estimated first heater pattern reaction
extent.
Embodiment 10
[0109] The method of any one of embodiments 2-9, wherein (g) and
(h) occur when (f) occurs.
Embodiment 11
[0110] The method of any one of embodiments 2-9, wherein (g) and
(h) occur after (f) occurs.
* * * * *