U.S. patent application number 10/084402 was filed with the patent office on 2002-10-17 for in-situ combustion restimulation process for a hydrocarbon well.
Invention is credited to Shaw, Donald R..
Application Number | 20020148608 10/084402 |
Document ID | / |
Family ID | 26770939 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020148608 |
Kind Code |
A1 |
Shaw, Donald R. |
October 17, 2002 |
In-situ combustion restimulation process for a hydrocarbon well
Abstract
A process of enhancing hydrocarbon production from wells
previously hydraulically fractured with a polymer based fluid(s).
An in-situ combustion process is initiated in the reservoir for a
short duration wherein thermal and chemical processes act to reduce
the viscosity of unbroken gels and other fluids retained in the
propped hydraulic fracture and immediate reservoir matrix
vicinity.
Inventors: |
Shaw, Donald R.; (Denver,
CO) |
Correspondence
Address: |
Bruce A. Kugler, Esq.
SHERIDAN ROSS P.C.
Suite 1200
1560 Broadway
Denver
CO
80202-5141
US
|
Family ID: |
26770939 |
Appl. No.: |
10/084402 |
Filed: |
February 25, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60273294 |
Mar 1, 2001 |
|
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|
Current U.S.
Class: |
166/251.1 ;
166/257; 166/259; 166/260; 166/261 |
Current CPC
Class: |
E21B 43/25 20130101 |
Class at
Publication: |
166/251.1 ;
166/257; 166/260; 166/261; 166/259 |
International
Class: |
E21B 043/243; E21B
043/247; E21B 047/06 |
Claims
What is claimed is:
1. A method for restimulating a previously fractured hydrocarbon
reservoir comprising the steps of: a) shutting in a producing well
bore in communication with said previously fractured hydrocarbon
reservoir to prevent flow; b) displacing at least a portion of a
hydrocarbon product existing in said producing well bore with a
fluid; c) injecting air down said hydrocarbon well bore and into
the hydrocarbon reservoir to create an in-situ combustion reaction
in said previously fractured hydrocarbon reservoir; d) shutting in
the hydrocarbon well bore for a period of at least about 12 hours;
and e) producing the hydrocarbon products from said well bore.
2. The method of claim 1, wherein said previously fractured
hydrocarbon reservoir includes a residual polymer.
3. The method of claim 1, further comprising the step of monitoring
a bottom-hole temperature of said producing well bore.
4. The method of claim 1, further comprising the step of injecting
a combustion catalyst into said hydrocarbon reservoir.
5. The method of claim 4, wherein said combustion catalyst
comprises at least one transitional metal in the form of a metallic
salt.
6. The method of claim 1, wherein said hydrocarbon reservoir fluids
have an API gravity of no less than about 35 degrees.
7. The method of claim 1, wherein a combustion temperature in said
hydrocarbon reservoir does not exceed about 700.degree. F.
8. The method of claim 1, wherein the volume of air injected into
said hydrocarbon reservoir is at least about ten times the volume
of an existing permeable fracture found in said previously
fractured reservoir.
9. The method of claim 1, further comprising the step of increasing
the percentage of oxygen present in said injected air to enhance
said in-situ combustion reaction.
10. The method of claim 1, wherein said step of displacing at least
a portion of a hydrocarbon product in said producing well bore
comprises injecting water down said well bore.
11. The method of claim 1, wherein said step of displacing at least
a portion of a hydrocarbon product in said producing well bore
comprises injecting a nitrogen gas down said well bore.
12. The method of claim 1, further comprising an ignition step to
initiate said in-situ combustion process.
13. The method of claim 12, wherein said ignition step comprises
the steps of: a) injecting an air mixture at a surface rate of
between about 50,000 to 100,000 standard cubic feet per day per
foot of perforations; b) restricting injection pressure below a
reservoir fracture pressure; and c) maintaining a continuous
injection of said air mixture for a time period not less than about
5 hours.
14. A method of improving the productivity of a previously
fractured hydrocarbon reservoir, comprising the steps of: a)
providing a well bore in communication with the previously
fractured hydrocarbon reservoir having an API fluid gravity of at
least about 35 degrees; b) shutting in said producing well bore; c)
injecting a non-combustible fluid down said well bore to evacuate
said well bore of substantially any combustible hydrocarbons; d)
injecting a predetermined volume of air down said well bore and
into said previously fractured hydrocarbon reservoir to initiate an
in-situ combustion reaction and generate heat; e) shutting in said
well bore for a predetermined period of time; and f) producing a
hydrocarbon product from said previously fractured hydrocarbon
reservoir and said well bore.
15. The method of claim 14, wherein said heat generated in said
previously fractured hydrocarbon reservoir improves the fracture
conductivity and adjacent reservoir permeability by reducing a
viscosity of a residual polymer gel present in at least a portion
of a fracture system in said previously fractured hydrocarbon
reservoir.
16. The method of claim 14, further comprising the step of
monitoring a bottom-hold temperature of said well bore to assure
said bottom hole temperature does not exceed about 1000.degree.
F.
17. The method of claim 14, further comprising the step of
injecting combustion catalyst into said hydrocarbon reservoir.
18. The method of claim 17, wherein said combustion catalyst
comprises a transitional metal in the form of metallic salt.
19. The method of claim 14, further comprising the step of
injecting a noncombustible fluid down said well bore prior to
producing a hydrocarbon product from said well bore.
20. A method for restimulating a previously fractured hydrocarbon
reservoir comprising the steps of: a) shutting in a producing well
bore in communication with said previously fractured hydrocarbon
reservoir to prevent flow; b) displacing at least a portion of a
hydrocarbon product existing in said producing well bore with a
fluid; c) injecting air down said hydrocarbon well bore and into
the hydrocarbon reservoir to create an in-situ combustion reaction;
d) shutting in the hydrocarbon well bore for a period of at least
12 hours; and e) producing the hydrocarbon products from said well
bore.
Description
[0001] This application claims priority of U.S. provisional patent
application Serial No. 60/273,294 having a filing date of Mar. 1,
2001 and is incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] This process generally relates to a process for enhancing
the recovery of hydrocarbons from a producing hydrocarbon zone.
More specifically, it relates to enhancing permeability in an
already propped fracture by removing unbroken or residual polymer
based gel fracturing fluids. When removed, flow from previously
undrained portions of the hydrocarbon reservoir is established or
enhanced.
BACKGROUND OF THE INVENTION
[0003] Many different processes have been employed to enhance the
recovery of hydrocarbons (liquids and/or gases) from subterranean
formations/reservoirs. This includes improving the rate of flow
and/or the ultimate recovery of hydrocarbons from a producing
hydrocarbon reservoir. Hydraulic fracturing is one such method
known in the petroleum industry to accomplish this goal. This
process if most often plied where transmissibility (kh/.mu.) is
low, most frequently in low permeability gas formations. Typical
fracturing fluids used to enhance reservoir productivity during
hydraulic fracturing techniques include, but are not limited to 1)
water-based systems which are normally comprised of polymer gels;
2) oil-based systems which are often gelled; 3) foam based systems;
and 4) alcohol based systems.
[0004] Early water and oil based systems have been extensively
referenced in the literature for their ineffectiveness due to the
inherent inability of the gels not to "break", i.e., become less
viscous and ultimately produced from the reservoir. In some cases,
unbroken gels have been inadvertently produced from these well
bores years later, long after they should have broken. The original
design emphasis on these gel systems was reduced surface tension
and increased viscosity to reduce friction and maximize sand
carrying capacity. Unfortunately, breaking these systems was not
well understood nor accomplished.
[0005] Recognizing the benefits of oxidation in gel degradation,
remediation attempts by injecting strong oxidizers such as chlorine
bleach have previously been attempted. The outcome was usually
unsuccessful, due primarily to the inability of an injected fluid
phase contacting the damaged area. Thus, the petroleum industry is
plagued worldwide with thousands of damaged hydrocarbon reservoirs
with extensively propped hydraulic fractures that are
non-productive due to residual polymer gels, thus resulting in low
productivity and the inherent loss of recoverable hydrocarbon
reserves and significant revenue.
[0006] The prior art has generally addressed the problem of low
productivity in hydrocarbon reservoirs by focusing on heavy crude
oil (<35 API gravity) reservoirs. Thus, attempts have previously
been made to establish a combustion zone in a carbonaceous stratum
by the injection of air, oxygen enriched air, or pure oxygen
through an independent injection well. As the combustion supporting
gas is injected, products of combustion and other heated fluids are
forced away from the point of injection within the producing
reservoir formation toward one or more producing wells where they
are withdrawn to the surface. Associated production increases
result from 1) increased pressure around a designated injection
well driving reservoir fluids toward a producing well; or 2) an
associated reduction in oil viscosity achieved through an increase
in temperatures of the oil and the surrounding rock matrix.
Examples of previous attempts at downhole combustion may be found
generally in U.S. Pat. No. 4,566,536 to Holmes, U.S. Pat. No.
5,868,202 to Hsu, U.S. Pat. No. 4,274,487 to Hollingsworth, U.S.
Pat. No. 4,418,751 to Emery, U.S. Pat. No. 4,042,026 to Pusch and
U.S. Pat. No. 4,557,329 to Savard.
[0007] Typical heavy crude oil reservoirs are generally shallow
(<3500 ft. depth) with low (<120.degree. F.) bottom hole
temperatures. The thermodynamic properties of these viscous oils
require long injection times (weeks to months) and high
temperatures (>700.degree. F.) to achieve in-situ ignition.
These problems were addressed in part by utilizing oxygen enriched
air or pure oxygen as the injection stream, and at times used in
combination with bottom-hole ignition systems. However, the
injection of pure oxygen creates safety issues due to the hazardous
nature of uncontrolled reactions or explosions associated with
hydrocarbon products exposed to extreme heat. U.S. Pat. No.
4,598,772 to Holmes and U.S. Pat. No. 4,440,227 to Holmes are
examples of attempts to mitigate unintended ignition and manage
well bores within safe operating levels.
[0008] Those skilled in the art will appreciate that low
temperature oxidation ("LTO") processes cause reservoir oil to
become partially oxidized and thereby form volatile oxygenated
compounds and unstable hydro peroxide intermediates. Their
decomposition releases significant heat. As the temperature
produced by such reactions is raised, intermediate temperature
reactions ("ITR") cause distillation and thermal cracking which
produces hydrogen gas and light hydrocarbons that are left as
carbonaceous residue on solid matrix materials in the formation. As
the reservoir temperature continues to rise to a minimum active
combustion temperature ("MACT"), a high temperature oxidation
("HTO") reaction occurs between the gaseous oxygen phase and the
deposited carbonaceous residue. Ignition in heavy oils generally
occurs in the HTO region wherein temperatures reach levels high
enough to ignite and burn the deposited carbonaceous material. For
reasons not fully understood, light oils and gas condensates will
ignite and burn in the LTO region. Accelerated Rate Calorimeter
tests performed on a specific light oil (50 API gravity) supported
ignition within hours versus days or weeks, with a MACT of less
than 500.degree. F. These lower generated temperatures for the
combustion of light oils allows In-situ combustion for most
existing producing wells without requiring prohibitive surface or
bottom-hole design changes.
[0009] Hydrocarbon oxidation by transition metal compounds is
recognized in the refining and processing of oil and gas. The
addition of such compounds can significantly increase oxidation
reactions, and thus shorten the time to ignition. For In-situ
combustion processes, this is important where the thermodynamic
qualities of the target oil and reservoir temperature would require
unreasonably long periods of oxygen injection to achieve ignition.
There is thus a significant need for a cost effective process for
stimulating previously fractured well bores with damage caused from
polymer gels in a safe, effective manner using an in-situ
combustion process.
[0010] Successful implementation of the process requires
maintaining a combustion front through the reservoir at some
distance from the injection well, a problem that has rendered a
majority of heavy oil thermal recovery projects unsuccessful. The
process of the present invention injects air for a short duration
to achieve in-situ combustion, and advance the combustion front
radially a small distance from the hydraulic fracture. The well is
then shut-in for a predetermined period to allow for maximum oxygen
utilization, bottom-hole temperature abatement to within safe
operating levels, and CO2 miscibility with reservoir oil.
SUMMARY OF THE INVENTION
[0011] It is thus one aspect of the present invention to employ an
in-situ combustion process in a hydrocarbon reservoir to remediate
production impairment in general and to improve the productivity
and total recovery of produced hydrocarbons from a producing
hydrocarbon reservoir. In one embodiment of the present invention
the process is specifically designed to reduce the production
impairment caused by the previous use of a polymer based hydraulic
fracturing fluids. The formation of, and reduced conductivities
created by polymer gel residues and unbroken gels are some of the
more common forms of damage caused by fracture fluids. Thus, the
gel residues and unbroken gels act as barriers to fluid flow in a
formation that is damaged in this manner.
[0012] In another aspect of the present invention, a process is
provided which is preferably carried out through a single well bore
that has been previously treated with any form of a polymer gel
based system. One primary benefit of the process described herein
is the degradation and removal of unbroken gels in the existing
propped hydraulic fracture system. Combustion processes used in
this application have several novel characteristics which
contribute to polymer gel degradation, including but not limited
to:
[0013] 1) Oxidation through contact by injected air;
[0014] 2) Elevated temperatures between 400.degree. F. to
700.degree. F.;
[0015] 3) Organic acids generated as a by-product of combustion
distillation; and
[0016] 4) Low PH water generated as a by-product of combustion
distillation.
[0017] It is a further aspect of the present invention to
facilitate the removal of localized connate water and/or retrograde
condensation through reduced surface tensions created by elevated
temperatures. Further, the treatment creates an effective fracture
having higher fracture conductivity and/or which penetrates an area
of higher pore pressure than the previous fracture and thus
enhances productivity and the ultimate recovery from the
hydrocarbon reservoir.
[0018] It is a further aspect of the present invention to provide a
process which can be practiced at a fraction of the cost of
conventional hydraulic fracturing techniques and which utilizes
equipment well known in the Petroleum Industry, and which can be
effectively implemented in a period of days as opposed to weeks or
months. Thus, in one aspect of the present invention, conventional
compressors for the injection of high pressure air are utilized, as
well as commonly used high pressure nitrogen gas.
[0019] Thus, in one embodiment of the present invention, a method
for restimulating a previously fractured hydrocarbon reservoir is
provided, and comprises the steps of:
[0020] a) shutting in a producing well bore in communication with
said previously fractured hydrocarbon reservoir to prevent
flow;
[0021] b) displacing at least a portion of a hydrocarbon product
existing in said producing well bore with a fluid;
[0022] c) injecting air down said hydrocarbon well bore and into
the hydrocarbon reservoir to create an in-situ combustion reaction
in said previously fractured hydrocarbon reservoir;
[0023] d) shutting in the hydrocarbon well bore for a period of at
least about 12 hours; and
[0024] e) producing the hydrocarbon products from said hydrocarbon
reservoir.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a top plan view of a theoretical well bore which
has been hydraulically fractured and identifying an effective
drained area and a fracture created during the stimulation
process;
[0026] FIG. 2 is a top plan view of a well bore identifying the
geometry of the actual hydraulic fracture and showing the effective
area of drainage;
[0027] FIG. 3 is a top plan view of a well bore with a
pre-treatment area of drainage and a post-treatment area of
drainage and depicting the subsequent improvement in productivity
based on the method of the present invention;
[0028] FIG. 4 is a front elevation view of a typical well bore of
the present invention and identifying the flow of air into the
hydrocarbon producing reservoir and showing the propagation of heat
into the surrounding rock matrix;
[0029] FIG. 5 is a front elevation view of the well bore shown in
FIG. 4 after treatment and identifying the production of
hydrocarbons into the well bore and the increase in the effective
area of drainage;
[0030] FIG. 6 is a top plan view of a wellhead in the present
invention and identifying the flow of air and nitrogen and
subsequent production of well bore fluids into a separator or flat
tank; and
[0031] FIG. 7 is a front elevation view of the well bore of the
present invention and identifying the producing reservoir and the
injection of air and nitrogen and the subsequent production of
produced fluids through the production tubing.
DETAILED DESCRIPTION
[0032] Referring now to the drawings, FIGS. 1-7 depict various
views of a hydraulically fractured reservoir, the penetrating well
bore, and the equipment associated with the present invention. More
specifically, FIG. 1 depicts a top plan view of a theoretical well
bore 6 and associated reservoir which has been hydraulically
fractured and further showing the effective drained area 8. FIG. 1
represents a hypothetical or ideal plan view wherein the fracture
wings generated by the hydraulic treatment are shown extending
horizontally into the hydrocarbon reservoir 2. These fractures are
"propped" open by materials such as sand or ceramic beads, thus
increasing the permeability and transmissibility of the reservoir
fluids and the rate of flow entering the well bore.
[0033] FIG. 2 is a plan view of a well bore 6 and identifying the
actual geometry of a typical hydraulic fracture 4 extending into a
hydrocarbon reservoir 2. The darker regions of the fracture wings 4
depict a zone damaged by residual polymers remaining after
hydraulic fracturing and thus not effective for the production of
hydrocarbons. More specifically, as the distance increases away
from the well bore 16 the fractures become ineffective due to the
presence of unbroken, highly viscous fracture fluids and residues.
This creates a decreased pressure drop away from the well bore 6
which combines to make the fluids immobile and impermeable to oil
and gas production past the effective fracture zone, thus resulting
in reduced production outside of the effective drained area 8.
[0034] FIG. 3 depicts a plan view of the well bore 6 shown in FIG.
2 and the associated hydrocarbon reservoir 2 of the present
invention and identifies an increased post treatment area of
drainage 10 once the residual polymers and other well bore damage
is removed from the hydraulically fractured area. Accordingly, a
more effective fracture and improved permeability in the rock
matrix is obtained in the treated hydrocarbon reservoir 2.
[0035] Referring now to FIG. 4, a front elevation view of a typical
well bore 4 of the present invention is provided herein and which
shows casing 12 penetrating a hydrocarbon reservoir 2. In this
particular schematic, the injected air is shown being introduced
through the perforations 14 and into the hydrocarbon reservoir 2 to
create an oxidation process which generates significant heat. The
heat and combustion front is advanced and replenished by the cooler
injected air, and the propagation of the heat continues along the
hydraulic fracture 4 network into the surrounding rock matrix as it
is propelled by the available air and oxygen. This effectively
creates carbon dioxide gases, low ph water and peroxide byproducts
and distillation which assist in the thermal degradation of
entrained fracture fluids and the mobilization of the broken gelled
fluids and the improved productivity of the hydrocarbon reservoir
2.
[0036] FIG. 5 is a depiction of the well bore 6 shown in FIG. 4,
but identifies the production of hydrocarbons after the injection
process and treatment of the present invention is completed. More
specifically, after the air injection has been discontinued, the
bottom hole temperature is allowed to cool to a specified level and
the well returned to production. The rate of production is enhanced
due to the increased effective fracture length, resulting from the
breakdown of viscous polymer gels, which allows contact with higher
reservoir pressure and improved permeabilities in the fracture and
surrounding rock matrix, hence improving production rates and total
recovery of hydrocarbon fluids.
[0037] FIG. 6 is a top plan view identifying equipment utilized in
one aspect of the present invention. More specifically, a
compressor 15 used to inject the air necessary for combustion,
while a nitrogen source maybe used for injection down the annulus
between the production tubing 16 and casing 12 and the subsequent
necessity of a separator for use during production after treatment.
Further, an open top flat tank may additionally be used for sales
or the removal of water or other byproducts.
[0038] FIG. 7 is a front elevation view of one aspect of the
present invention and further identifies the hydrocarbon reservoir
2, well bore casing 12, production tubing 16, injection lines
necessary for the injection of the air and nitrogen, as well as the
valves and associated piping required for the present method of
treatment. Additionally, a thermocoupler is shown which may be used
to monitor the bottom hole temperature throughout the process of
the present invention to assure temperatures do not exceed design
limitations. FIG. 7 further depicts the well bore 6 extending from
the surface of the earth through the overburden and extending into
the target hydrocarbon producing formation from which hydrocarbons
are recovered by an in-situ combustion process of the present
invention.
[0039] In one aspect of the present invention, the operation of the
system is as follows. A predetermined amount of water is pumped
down the tubing in sufficient volume to kill the well and evacuate
the lower portion of oil, condensate or other hydrocarbon products.
If metallic salts are required as a combustion catalyst, a
predetermined volume is mixed with the water prior to injection.
These metallic salts may include, but are not limited to Ammonium,
Magnesium, Bismuth, Manganese, Calcium, Nickel, Cobalt, Potassium,
Copper, Silver, Iron, Sodium or other transition metal complexes as
identified on a periodic chart. Nitrogen is then injected down the
casing 12 and production tubing 16 in sufficient quantity to
over-flush the associated well bore 6 volume from surface to the
base of the perforations 14. Air or oxygen enriched air is then
injected into the hydrocarbon reservoir 2 via the tubing 16 at a
predetermined constant rate until ignition is indicated by a
significant increase in bottom-hole temperature as indicated by the
thermocoupler or sudden increases in surface injection pressures.
Air injection is continued until a predetermined amount of air
volume has been injected or pressures meet certain limits that
exceed hydraulic fracture pressures for the Rock Matrix of the
hydrocarbon reservoir 2. It is intended that air be injected at
pressures that allow diffusion down the previous hydraulic fracture
4 and into the rock matrix, but not to create additional fractures
which would diminish the effectiveness of the present
treatment.
[0040] In one embodiment of the present invention, air injection is
immediately followed by nitrogen gas in sufficient volumes to
over-displace the tubing volume by at least 50%. As an inert gas,
the Nitrogen gas serves to protect the well bore 6 from propagation
of the combustion front back into the well bore and the inherent
problems associated with excessive temperatures. As appreciated by
one skilled in the art, other inert gases may also be used for the
same purpose. The well bore 6 is then shut-in and bottom-hole
temperatures are monitored by the thermocoupler. The well is then
produced to an open top flat tank and flue gases vented until the
bottom-hole temperatures have subsided to within safe operational
levels, which typically occurs in a period of about 24 hours. Flue
gases are additionally monitored until O2 and N2 levels are deemed
to be within accepted pipeline levels, at which time the well is
returned to sales.
[0041] As one example of the present invention, the following
actual procedure is described below for a hydrocarbon reservoir
having a depth of 6700 ft. which was penetrated by 4.5" casing 12
and 23/8" production tubing 16:
[0042] Procedure:
[0043] Embodiment 1--All Perforated Intervals to Be Treated
[0044] 1. Shut-in Offset producing wells
[0045] 2. Pressure test casing to rated minimum wellhead pressure
of 3000 psia.
[0046] 3. Flush tubing with enough water to void the well bore
volume from the top of the perforations to the bottom of the
hole.
[0047] Note: In one preferred embodiment of the present invention,
a combination of substances (chemical soups, principally comprised
of various metallic salt compounds) are added to the water prior to
placement in the well bore, wherein combustion ignition times from
certain reservoir temperatures, pressures and air flux rates are
known.
[0048] 4. Place wireline thermocoupler down the tubing or
casing/tubing annulus to the base of the tubing to monitor bottom
hole temperature.
[0049] 5. Inject Nitrogen down the annulus at low rates and a total
volume of 1.5 times the annular tubing volume.
[0050] 6. Inject nitrogen down tubing at low rates and a total
volume of 1.5 times the tubing volume.
[0051] 7. Immediately follow Nitrogen injection down tubing with
air injection. Adjust air injection rates such that monitored
pressures are either 1) below maximum rated wellhead pressures or
2) below fracture initiation pressures of the formation.
[0052] 8. Continuously monitor surface pressures for a rid rise
indicative of combustion ignition.
[0053] 9. Periodically suspend air injection and monitor bottom
hole temperatures for an increase above baseline temperatures
indicating combustion ignition.
[0054] Note: If bottom hole temperatures exceed 800 degrees F.; 1)
immediately resume air injection and if they do not immediately
subside, 2) cease air injection and immediately follow with
nitrogen injection down tubing. Shut-in well until bottom hold
temperatures subside to 500 degrees F.; resume air injection.
[0055] 10. Continue air injection for a predetermined period of
time following combustion ignition (usually 3 to 48 hours).
[0056] 11. Inject nitrogen down tubing with a total volume of 1.5
times tubing volume.
[0057] 12. Shut-in the well for a predetermined period of time
(usually 2-5 days).
[0058] 13. Pull thermocoupler from the well bore.
[0059] 14. Flowback well to an open top flat tank. Swab if
necessary.
[0060] 15. Monitor oxygen and nitrogen levels of the vented gas
until levels have fallen below the designated containment levels
for the sales line.
[0061] 16. Return production to the sales line.
[0062] Embodiment 2--Selected Perforated Intervals to Be
Treated
[0063] 1. The process is as above with a packer positioned above a
bridge plug to isolate the perforation target intervals. This step
eliminates the annulus and the need to inject nitrogen in step 5
above.
[0064] To assist in the understanding of the present invention, the
following components and numberings associated with the drawings
are provided herein:
1 # Component 2 Hydrocarbon reservoir 4 Hydraulic fracture 6 Well
bore 8 Area of drainage 10 Post treatment area of drainage 12
Casing 14 Perforations 16 Production tubing 18 Valves 20
Thermocoupler 22 Injection lines
[0065] The foregoing description of the present invention has been
presented for purposes of illustration and description.
Furthermore, the description is not intended to limit the invention
to the form disclosed herein. Consequently, variations and
modifications commenced here with the above teachings and the skill
or knowledge of the relevant art are within the scope in the
present invention. The embodiments described herein above are
further extended to explain best modes known for practicing the
invention and to enable others skilled in the art to utilize the
invention in such, or other, embodiments or various modifications
required by the particular applications or uses of present
invention. It is intended that the dependent claims be construed to
include all possible embodiments to the extent permitted by the
prior art.
* * * * *