U.S. patent application number 10/811745 was filed with the patent office on 2005-09-29 for methods of stimulating water sensitive coal bed methane seams.
Invention is credited to Stromquist, Marty L..
Application Number | 20050211438 10/811745 |
Document ID | / |
Family ID | 34988417 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050211438 |
Kind Code |
A1 |
Stromquist, Marty L. |
September 29, 2005 |
Methods of stimulating water sensitive coal bed methane seams
Abstract
Methods of stimulating water sensitive coal bed seams containing
methane gas are disclosed. The methods comprise the steps of
contacting and heating the coal bed seam with hot nitrogen gas so
that the coal bed in the seam shrinks and forms methane gas flow
passages therein and producing the methane gas through the
passages.
Inventors: |
Stromquist, Marty L.;
(Linden, CA) |
Correspondence
Address: |
Robert A. Kent
Halliburton Energy Services
2600 South 2nd Street
Duncan
OK
73536-0440
US
|
Family ID: |
34988417 |
Appl. No.: |
10/811745 |
Filed: |
March 29, 2004 |
Current U.S.
Class: |
166/302 ;
166/272.1 |
Current CPC
Class: |
E21B 43/006 20130101;
E21B 43/24 20130101 |
Class at
Publication: |
166/302 ;
166/272.1 |
International
Class: |
E21B 043/34 |
Claims
What is claimed is:
1. A method of stimulating a water sensitive coal bed seam
containing methane gas penetrated by a well bore to enhance the
production of methane gas therefrom comprising the steps of: (a)
contacting and heating the coal bed seam with hot nitrogen gas so
that the coal bed in the seam shrinks and forms methane gas flow
passages therein; and (b) producing the methane gas through the
flow passages.
2. The method of claim 1 wherein the coal bed seam is under
saturated with low pressure methane gas.
3. The method of claim 1 wherein the hot nitrogen gas has a
temperature in the range of from about the in situ ambient
temperature to about 350.degree. F.
4. The method of claim 1 wherein the coal bed seam is contacted and
heated by pumping the hot nitrogen gas into the coal bed seam at a
low rate and pressure sufficient to heat and shrink the coal bed
thereby forming the methane flow passages therein.
5. The method of claim I wherein the nitrogen gas is pumped from
the surface into the coal bed seam.
6. The method of claim 1 wherein the nitrogen gas is heated in the
well bore by a heater disposed therein.
7. The method of claim 5 wherein the heater is selected from the
group consisting of electric heaters, electric heat exchangers and
friction heat exchangers.
8. The method of claim 1 wherein the well bore includes casing and
perforations extending into the coal bed seam.
9. The method of claim 1 wherein the heater is positioned in the
well bore adjacent to or near the coal bed seam.
10. The method of claim 1 wherein the nitrogen gas is pumped
through coiled tubing disposed in the well bore.
11. The method of claim 10 wherein the heater is connected to the
coiled tubing.
12. The method of claim 10 wherein the coiled tubing includes
packers above and below the coal bed seam.
13. A method of stimulating a water sensitive coal bed seam
penetrated by a well bore that is under saturated with low pressure
methane gas comprising the steps of: (a) providing a source of
nitrogen gas on the surface and pumping the nitrogen gas at a
relatively low rate by way of a heater disposed in the well bore
into the coal bed seam; (b) heating the nitrogen gas by the heater
to a temperature in the range of from about the in situ ambient
temperature to about 350.degree. F. so that the nitrogen gas heats
the coal bed and causes it to shrink and form enlarged methane gas
flow passages therein; and (c) producing methane gas from the coal
bed by way of the flow passages.
14. The method of claim 13 wherein the heater is selected from the
group consisting of electric heaters, electric heat exchangers and
friction heat exchangers.
15. The method of claim 13 wherein the well bore includes casing
and perforations extending into the coal bed seam.
16. The method of claim 13 wherein the heater is positioned in the
well bore adjacent to or near the coal bed seam.
17. The method of claim 13 wherein the nitrogen gas is pumped
through coiled tubing disposed in the well bore.
18. The method of claim 13 wherein the heater is connected to the
coiled tubing.
19. The method of claim 13 wherein the coiled tubing includes
packers above and below the methane gas seam.
20. The method of claim 13 wherein the coal bed seam is one of a
plurality of thin coal bed seams penetrated by the well bore.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to methods of stimulating
water sensitive coal bed methane seams that are under saturated
with low pressure methane gas.
[0003] 2. Description of the Prior Art
[0004] The production of methane from subterranean coal beds by way
of wells drilled into the coal beds has been practiced for many
years. Generally, the coal beds contain absorbed hydrocarbon gases
consisting primarily of methane. The coal beds usually contain
water which when produced causes pressure to be reduced and the
methane and other gases to be desorbed from the coal and produced
along with the water.
[0005] In some areas containing a plurality of thin coal bed seams,
the methane gas in the seams has a low pressure and the seams are
under saturated. A typical such field has from about 10 to about 40
thin coal bed seams in a 1,500 foot vertical well bore. These coal
bed seams do not contain water and when the coal in the seam is
exposed to water, it becomes plugged and the methane gas will not
flow through the coal. As a result, the coal bed seams have been
fractured with nitrogen gas utilizing coiled tubing and packers
above and below the seam being fractured. The nitrogen gas rates
utilized in the fracturing process have generally been about 5,400
standard cubic feet of nitrogen per foot of coal thickness. In
order to provide the high rate of nitrogen gas, multiple high
pressure pumper trucks are required making the operation very
complex and expensive to carry out.
[0006] Thus, there is a need for simpler and less expensive methods
of forming flow passages in thin coal bed seams containing
methane.
SUMMARY OF THE INVENTION
[0007] The present invention provides methods of stimulating water
sensitive coal bed seams that are under saturated with low pressure
methane gas which meet the above described need and overcome the
deficiencies of the prior art.
[0008] A method of this invention for stimulating a water sensitive
coal bed seam containing methane gas penetrated by a well bore to
enhance the production of methane gas therefrom comprises the
following steps. The coal bed seam is contacted and heated with hot
nitrogen gas so that the coal bed in the seam shrinks and forms
methane gas flow passages therein. Thereafter, the methane gas is
produced through the flow passages.
[0009] Another method of the present invention for stimulating a
water sensitive coal bed seam penetrated by a well bore that is
under saturated with low pressure methane gas comprises the
following steps. A source of nitrogen gas is provided on the
surface and the nitrogen gas is pumped at a relatively low rate by
way of coiled tubing and a heater disposed in the well bore into
the coal bed seam. The nitrogen gas is heated by the heater to a
temperature in the range of from about the in situ ambient
temperature to about 350.degree. F. so that the nitrogen gas heats
the coal bed and causes it to shrink and form enlarged methane gas
flow passages therein. Thereafter, the methane gas is produced from
the coal bed by way of the flow passages therein.
[0010] The objects, features and advantages of the present
invention will be readily apparent to those skilled in the art upon
a reading of the description of preferred embodiments which
follows.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0011] As mentioned, water sensitive coal bed seams containing
under saturated low pressure methane gas have heretofore been
difficult and expensive to fracture whereby the methane gas can be
produced. The present invention provides methods of stimulating the
thin water sensitive coal bed seams which are substantially less
expensive than the prior art methods and allow the coal bed seam
methane gas to be readily produced.
[0012] The methods of the present invention for stimulating a water
sensitive coal bed seam containing under saturated low pressure
methane gas penetrated by a well bore basically comprises the
following steps. The coal bed seam is contacted and heated with hot
nitrogen gas so that the coal bed in the seam shrinks and forms
methane gas flow passages therein. Thereafter, the methane gas is
produced through the flow passages.
[0013] The hot nitrogen gas is pumped into a coal bed seam at a low
rate and pressure sufficient to heat and shrink the coal bed
thereby forming methane flow passages therein. The particular flow
rate and pressure of the nitrogen gas required is such that the
coal bed seam is contacted by the hot nitrogen gas and heated over
a desired length in a desired period of time.
[0014] The nitrogen gas is pumped from the surface into the coal
bed seam and the nitrogen gas is heated in the well bore by a
heater disposed therein to a temperature in the range of from about
the in situ ambient temperature to about 350.degree. F., preferably
about 212.degree. F.
[0015] A variety of heaters suitable for being positioned within
the well bore can be utilized including, but not limited to,
electric heaters or electric or friction heat exchangers.
Generally, the well bore includes casing and perforations extending
into the coal bed seam and the heater is positioned in the well
bore adjacent to or near the coal bed seam. The nitrogen gas is
preferably pumped through coiled tubing disposed in the well bore
connected to the heater and packers are utilized to isolate the
coal bed seam being treated.
[0016] A more detailed method of this invention for stimulating a
water sensitive coal bed seam that is under saturated with low
pressure methane gas comprises the following steps. A source of
nitrogen gas is provided on the surface and the nitrogen gas is
pumped at a relatively low rate by way of coiled tubing and a
heater disposed in the well bore into the coal bed seam. The
nitrogen gas is heated in the heater to a temperature in the range
of from about the in situ ambient temperature to about 350.degree.
F., preferably about 212.degree. F. so that the nitrogen gas heats
the coal bed and causes it to shrink and form enlarged methane gas
flow passages therein. Thereafter, the methane gas in the coal bed
seam is produced by way of the flow passages.
[0017] In a well bore that contains a plurality of spaced apart
thin coal bed seams, each coal bed seam is separately stimulated in
accordance with this invention whereby methane gas is readily
produced from the coal bed seams. The well bore is preferably cased
and perforations extend into each of the coal bed seams. As each
coal bed seam is stimulated, the packers, the coiled tubing and the
heater are positioned in the well bore adjacent to or near the next
coal bed seam to be stimulated.
[0018] A preferred method of this invention for stimulating a water
sensitive coal bed seam containing methane gas penetrated by a well
bore to enhance the production of methane gas therefrom comprises
the steps of:
[0019] (a) contacting and heating the coal bed seam with hot
nitrogen gas so that the coal bed in the seam shrinks and forms
methane gas flow passages therein; and
[0020] (b) producing the methane gas through the flow passages.
[0021] Another preferred method of this invention for stimulating a
water sensitive coal seam penetrated by a well bore that is under
saturated with low pressure methane gas comprises the steps of:
[0022] (a) providing a source of nitrogen gas on the surface and
pumping the nitrogen gas at a relatively low rate by way of coiled
tubing and a heater disposed in the well bore into the coal bed
seam;
[0023] (b) heating the nitrogen gas by the heater to a temperature
in the range of from about the in situ ambient temperature to about
350.degree. F. so that the nitrogen gas heats the coal bed and
causes it to shrink and form enlarged methane gas flow passages
therein; and
[0024] (c) producing methane gas from the coal bed by way of the
flow passages.
[0025] Thus, the present invention is well adapted to attain the
ends and advantages mentioned as well as those which are inherent
therein. While numerous changes may be made by those skilled in the
art, such changes are encompassed within the spirit of this
invention as defined by the appended claims.
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