U.S. patent number 3,774,701 [Application Number 05/141,215] was granted by the patent office on 1973-11-27 for method and apparatus for drilling.
Invention is credited to Carnes W. Weaver.
United States Patent |
3,774,701 |
Weaver |
November 27, 1973 |
METHOD AND APPARATUS FOR DRILLING
Abstract
A method and apparatus for rotary drilling an earth formation
with a cutting tool using air as a non-polluting circulating
drilling fluid including expansion of cooled and compressed air to
cool and clean the cutting tool, to remove cuttings from the drill
hole and to freeze the moisture in the formation adjacent the drill
hole to prevent sloughing of the walls into the drill hole. Side
ports on the cutting tool provide additional cooling to the
circulating air for cooling the walls of the drill hole. An
anti-freeze solution is added to the circulating air to prevent
freezing of water in the well hole. The method may also be used in
obtaining core samples having the moisture therein frozen.
Inventors: |
Weaver; Carnes W. (Houston,
TX) |
Family
ID: |
22494696 |
Appl.
No.: |
05/141,215 |
Filed: |
May 7, 1971 |
Current U.S.
Class: |
175/17; 166/901;
175/71; 175/59; 405/130 |
Current CPC
Class: |
E21B
49/02 (20130101); E21B 21/16 (20130101); E21B
7/00 (20130101); E21B 36/001 (20130101); Y10S
166/901 (20130101) |
Current International
Class: |
E21B
21/16 (20060101); E21B 36/00 (20060101); E21B
49/02 (20060101); E21B 21/00 (20060101); E21B
7/00 (20060101); E21B 49/00 (20060101); E21b
007/00 () |
Field of
Search: |
;175/17,65,66,72
;166/DIG.1 ;61/36A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Champion; Marvin A.
Assistant Examiner: Favreau; Richard E.
Claims
What is claimed is:
1. A method of drilling through an earth formation with a drill
string having a bore communicating with a ported cutting tool at
the formation engaging end including:
a. lowering the temperature of a supply of air;
b. communicating the air into the bore of the drill string;
c. reducing the pressure of the air adjacent the ports of the
cutting tool to cool the cutting tool;
d. directing the air about the cutting tool;
e. flowing the reduced pressure air upwardly along the outer
surface of the drill string away from the cutting tool; and
f. venting a portion of the air in the bore of the drill bit into
the flowing reduced pressure air to cool the flow of air
circulating from the drill bit.
2. A method of drilling through an earth formation with a drill
string having a bore communicating with a ported cutting tool at
the formation engaging end including:
a. lowering the temperature of a supply of air;
b. communicating the air into the bore of the drill string;
c. reducing the pressure of the air adjacent the ports of the
cutting tool to cool the cutting tool;
d. directing the air about the cutting tool;
e. flowing the reduced pressure air upwardly along the outer
surface of the drill string away from the cutting tool; and
f. venting a portion of the air in the bore of the drill bit into
the flowing reduced pressure air to cool the flow of air
circulating from the drill bit; and
g. adding a water freezing temperature depressant to the air
injected in the bore of the drill string to enable removal of the
water in the drill hole.
3. The method as set forth in claim 2, including:
a. rotating a drill bit cutting tool while moving the bit into the
formation to produce a drill hole;
b. cooling the cutting edges of the drill bit and the formation
adjacent the bit with the reduced pressure air; and
c. removing the formation cuttings from the drill hole with the
flowing reduced pressure air circulating from the drill bit.
4. The method as set forth in claim 2, wherein the flowing reduced
pressure air cools the walls of the drill hole to freeze the
moisture adjacent the drill hole to prevent sloughing of the drill
hole walls into the drill hole.
5. The method as set forth in claim 2 including:
a. rotating the cutting tool while moving the cutting tool into the
formation to produce a core sample; and
b. cooling the core sample in place to freeze the moisture within
the sample.
6. Apparatus for circulating a drilling fluid in an earth formation
boring operation including:
a. a rotary ported cutting tool for moving into the formation;
b. a supply of compressed air;
c. means for cooling the supply of compressed air;
d. means for communicating the supply of cooled compressed air to
the ports of the cutting tool wherein the cooled compressed air
flows through the ports in the cutting tool to expand to a lower
pressure for lowering the temperature of the air to clean and cool
the cutting tool; and
e. means for venting a portion of the supply of compressed air into
the lower pressure air enabling the vented portion to expand to a
lower pressure for cooling the lower pressure air and cuttings
below the freezing temperature of water.
7. The structure as set forth in claim 6 wherein the lower pressure
air cools and circulates formation cuttings from the cutting
tool.
8. The structure as set forth in claim 6 wherein a core sample cut
by said cutting tool is cooled in place by the lower pressure air
below the freezing temperature of water wherein the moisture in the
core is frozen.
9. A method of drilling through an earth formation with a drill
string having a bore communicating with a ported cutting tool at
the formation engaging end, including:
a. compressing a supply of air;
b. cooling the supply of compressed air;
c. communicating the supply of air into the bore of the drill
string;
d. cooling the cutting tool by expanding the air through the ports
of the cutting tool;
e. freezing the moisture in the formation by expanding the air
through the ports of the cutting tool to prevent sloughing of the
formation into the drill hole;
f. removing formation cuttings produced by the cutting tool with
the expanding air; and
g. cooling the expanding air from the cutting tool ports by
expanding an additional portion of the compressed air from the bore
of the drill string into the expanding air from the cutting tool
ports.
10. A method of drilling in arctic regions through an earth
formation with a drill string having a bore communicating with a
ported cutting tool at the formation engaging and including:
a. lowering the temperature of a supply of air;
b. communicating the air into the bore of the drill string;
c. reducing the pressure of the air adjacent the ports of the
cutting tool to cool the cutting tool;
d. directing the air about the cutting tool;
e. flowing the reduced pressure air upwardly along the outer
surface of the drill string away from the cutting tool; and
f. venting a portion of the air in the bore of the drill bit into
the flowing reduced pressure air to cool the flow of air
circulating form the drill bit.
11. The method as set forth in claim 10, including:
a. rotating a drill bit cutting tool while moving the bit into the
formation to produce a drill hole;
b. cooling the cutting edges of the drill bit and the formation
adjacent the bit with the reduced pressure air; and
c. removing the formation cuttings from the drill hole with the
flowing reduced pressure air circulating from the drill bit.
12. The method as set forth in claim 10, wherein the flowing
reduced pressure air cools the walls of the drill hole to freeze
the moisture adjacent the drill hole to prevent sloughing of the
drill hole walls into the drill hole.
13. The method as set forth in claim 10, including:
a. rotating the cutting tool while moving the cutting tool into the
formation to produce a core sample; and
b. cooling the core sample in place to freeze the moisture within
the sample.
14. The method as set forth in claim 10, wherein the step of
lowering the temperature of a supply of air includes:
vaporizing a supply of cryogenic liquid for cooling the supply or
air.
15. The method as set forth in claim 14, including the step of:
communicating the vaporized supply of cryogenic fluid into the bore
of the drill string.
16. The method as set forth in claim 14, including the step of:
using the vaporized supply of cryogenic fluid as a source of energy
for the drilling operation.
17. A method of drilling in arctic regions through an earth
formation With a drill string having a bore communicating with a
ported cutting tool at the formation engaging end including:
a. lowering the temperature of a supply of air;
b. communicating the air into the bore of the drill string;
c. reducing the pressure of the air adjacent the ports of the
cutting tool to cool the cutting tool;
d. directing the air about the cutting tool;
e. flowing the reduced pressure air upwardly along the outer
surface of the drill string away from the cutting tool; and
f. venting a portion of the air in the bore of the drill bit into
the flowing reduced pressure air to cool the flow of air
circulating from the drill bit; and
g. adding a water freezing temperature depressant to the air
injected in the bore of the drill string to enable removal of the
water in the drill hole.
Description
BACKGROUND OF THE INVENTION
This invention relates to the field of a method and apparatus
drilling operation and for obtaining core samples.
The use of a formation water freezing fluid as a circulating medium
in rotary well drilling operations was disclosed in U.S. Pat. Nos.
2,193,219, 2,621,022 and 3,424,254. These fluids polluted the
environment when they escaped from the circulating system or they
required large quantities of expensive or hard to store fluids.
U.S. Pat. No. 2,812,160 discloses an apparatus using special
coolants for obtaining frozen core samples.
SUMMARY OF THE INVENTION
This invention relates to a new and improved method and apparatus
for drilling.
The method includes compressing, cooling, dehydrating and injecting
a supply of air in the bore of a rotary drill string having a
ported cutting tool engaging the formation. The air pressure is
reduced while passing through ports in the drill bit to expand and
cool the air. The expanded or reduced pressure air is directed to
clean and cool the cutting tool as well as circulate formation
cuttings back to the surface. The flow back to the surface along
the outer surface of the drill string cools the walls of the drill
hole to freeze the moisture adjacent the drill hole to prevent
sloughing of the walls into the drill hole. Vent holes are provided
in the drill bit to vent a portion of the air into the circulating
flow from the drill bit to further reduce the temperature of the
air and formation cuttings flowing from the bit. Frozen core
samples may be obtained using the expansion of the air to freeze
the moisture in the sample.
The drilling apparatus includes a rotary ported earth formation
cutting tool, a supply of compressed air, means for cooling the
supply of compressed air and means for communicating the cooled
compressed air to the cutting tool. A means for venting a portion
of the compressed air to cool the reduced pressure air from the
cutting tool ports is also included.
An object of the present invention is to provide a new and improved
drilling method.
Another object of the present invention is to provide a new and
improved drilling method for use in arctic areas.
Yet another object of the present invention is to provide a new and
improved drilling apparatus.
A further object of the present invention is to provide a new and
improved drilling apparatus for a pollution free drilling
fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
The FIGURE is a schematic view illustrating an arrangement of
equipment utilized in the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The drawing illustrates an arrangement of the apparatus employed in
the method of the present invention. As will be explained in
detail, a portion of the apparatus is located on the earth surface
G and a portion is located in a drill hole H for extending the hole
H into an earth formation F.
The apparatus employed in the drill hole H includes a drill string
T and a formation cutting tool. The tubular drill string T has a
bore therein extending the length of the drill string T for
communicating with the cutting tool. The rotary cutting tool
includes a core sample cutting tool or a drill bit B having a
plurality of ports P located on the lower or cutting portion of the
drill bit B. A plurality of vent holes V are located on the upper
portion of the drill bit B. Flow passages within the drill bit B
communicate the bore of the drill string T with the vents V and the
ports P.
Located on the surface G is a rotary drilling rig (not shown) for
hoisting and rotating the drill string T, as is well known in the
art. The rotary table indicated at R provides a means for imparting
rotation to the drill string T for rotating the drill bit B. The
hook (not numbered) provides a support and a hoist means for the
drill string T and the drill bit B. The hook is connected to a
swivel S mounted with the drill string T for communicating the
drilling fluid into the bore of the rotating drill string T as will
be explained. A flexible conduit means C communicates the swivel S
and an outlet of a heat exchanger X for enabling vertical movement
of the swivel S while maintaining communication therebetween.
The drilling method and apparatus of the present invention utilizes
air and mixtures thereof with other gases as a circulating drilling
fluid. An intake filter is provided to initially remove solid
matter from the circulating air which may damage the equipment or
plug the apparatus as will be explained.
After passing through the filter, the air is communicated to a
dryer means for removing moisture from the air. Preferably, the
dryer is a closed container filled with any number of
desiccant-type materials or drying agents. For example, calcium
chloride or phosphorus pentoxide may be used. These agents are
capable of reducing the water content of contacted air to a low
value as is well known in the art.
After removal of moisture in the dryer, the air is communicated to
a compressor which provides a supply of compressed air for enabling
circulation of the air. Any type of compressor may be used, but a
reciprocating-type compressor having a speed control to control the
volume of air compressed is preferred. A pressure safety valve,
illustrated at 10, preferably of the spring biased type is mounted
with the compressor discharge conduit to prevent damage to the
equipment from over pressure of the system by the compressor.
Means for cooling the supply of compressed air includes the heat
exchanger X which provides cooling to the compressed air prior to
flowing into the conduit. The heat exchanger X may be of any type
but should have sufficient heat transfer surface area to lower to a
predetermined temperature the temperature of the compressed air to
enable the temperature of the air flowing from the drill hole H to
be maintained below the freezing temperature of water as will be
explained. Any type of coolant or cooling medium may be circulated
through the heat exchanger X to reduce the the temperature of the
air. The preferred embodiment utilizes a liquid cryogenic fluid
contained in an insulated tank or reservoir Z as a coolant. The
gaseous cryogenic fluid phase evaporating from the liquid phase is
communicated through the heat exchanger X for cooling the air
before venting to the atmosphere through a valve: illustrated at
12. The back pressure regulator valve 12 maintains a selected vapor
pressure on the cryogenic liquid which establishes the temperature
of the cryogenic fluid in the reservoir Z as is well known.
Means to directly inject the gaseous cryogenic fluid into the
stream of compressed air to provide additional cooling to the air
are included. A conduit 20 having a valve, indicated at 20a,
therein enables injection of the gaseous cryogenic fluid into the
stream of compressed air prior to cooling the air in the heat
exchanger X. Also, a conduit 21 having a block valve indicated at
21a, therein enables the injection of the gaseous cryogenic fluid
into the cooled stream of air flowing from the heat exchanger X,
and a conduit 22 having a block valve, indicated at 22a, therein
enables injection of the gaseous cryogenic fluid utilized to cool
the air into the stream of cooled air.
A reservoir M communicating with the conduit C through a conduit 30
having a block valve, indicated at 30a, therein serves as a means
for adding an anti-freeze material to the stream of compressed air.
The reservoir M is filled with a liquid material for lowering or
depressing the freezing temperature of water when mixed therewith.
For example, calcium chloride may be used as an anti-freeze
material.
In the use, operation and method of the present invention the
drilling rig is used to support and hoist the drill string T and
drill bit B as is well known in the art. The drill string T is
rotated by the rotary table R for enabling the drill bit B to move
further into the formation F as the well bore is drilled to produce
a drill hole H as is well known in the art.
The operation of the compressor creates an inlet suction pressure
differential which enables flow of air through the filter and the
dryer to the compressor inlet. Flow through the intake filter
removes a portion of the solid material from the stream of air
which may damage the cylinders of compressor or plug the vents V or
the ports P of the drill bit B. The dryer removes moisture from the
air to prevent freezing of the moisture when the air is cooled in
the heat exchanger X or expanded in the drill hole H as will be
explained. The dryer also reduces the quantity of anti-freeze from
reservoir M required. The compressor increases the pressure of the
air located in a chamber partially defined by the exchanger X, the
conduit C, the bore of the drill string T and the passages of the
drill bit B. By adjusting the speed of the compressor, the driller
controls the volume of air compressed into the fixed volume
chamber.
The relationship of pressure, volume and temperature of compressed
air are all interrelated and are readily calculated as is well
known. By increasing the speed of the compressor an additional
quantity or volume of air is compressed to increase the pressure in
the chamber. The compressor, while increasing the pressure of the
air also increases the temperature of the air as is well known. The
relief valve, indicated at 10, controls or limits the compressor
output from overpressuring the system and damaging the heat
exchanger X or rupturing the conduit C should the flow of
compressed air be blocked for any reason by venting the excess
pressure from the chamber. The compressed air is then passed
through the heat exchanger X to lower the temperature of the
air.
The gaseous phase of the cryogenic fluid is communicated through
the tubing of the heat exchanger X as a coolant to reduce the
temperature of the compressed air flowing through the heat
exchanger X. The gaseous cryogenic fluid is normally vented to
atmosphere through the back pressure regulator valve 12. The back
pressure regulator valve 12 maintains a predetermined fixed vapor
pressure on the cryogenic fluid in the reservoir Z which
establishes the temperature of the cryogenic fluid in the vessel Z
and the temperature of the fluid flowing through the tubing of the
heat exchanger X. By adjusting the valve 12, the driller may
control the temperature of the coolant and therefore the
temperature of the compressed air. The selected vapor pressure
depends on the cryogenic fluid employed. Use of a cryogenic liquid
as a coolant provides the driller with other advantages. If
nitrogen or another inert gas is used as a cryogenic fluid, the
discharge through the valve 12 will not pollute the atmosphere. If
liquified petroleum gas is used as the cryogenic fluid, the
discharge from the back pressure valve 12 may be contained and used
as a source of energy for the drilling operation.
In normal operation, the heat transfer in the exchanger X is
sufficient to cool the air flowing through the exchanger. Should
abnormal drilling conditions occur, means are included for
injecting nitrogen or other inert gaseous cryogenic fluids directly
into the stream of compressed air for additional cooling. The valve
20a may be opened and the cryogenic fluid injected through the
conduit 20 into the stream of compressed air prior to passing
through the heat exchanger X for additional cooling. The valve 21a
may be opened to enable the cryogenic gas to mix directly with the
compressed air down stream of the heat exchanger X for maximum
cooling. The gaseous cryogenic fluid may also be mixed with the
compressed air down stream of the heat exchanger X through conduit
22 by operation of the valve 22a to provide maximum use of the
cryogenic fluid. The various arrangements of injecting the gaseous
cryogenic fluid with the compressed air provides the driller with a
maximum flexibility for cooling the compressed air.
The cold compressed air flows from the exchanger X through the
check valve 11 into the conduit C and on into the swivel S. Flow is
then communicated down the bore of the drill string T to the drill
bit B. The compressed air then flows through the ports P and the
vents V of the drill bit B into the drill hole H and upwardly to
the surface S in the annulus between the outer surface of the drill
string T and the walls of the drill hole H.
In flowing through the ports P and the vents V, the drilling fluid
flows from a fixed volume area of higher pressure to an area of
reduced pressure resulting in expansion of the drilling fluid.
Because of the relationship between pressure, volume and
temperature, this expansion further cools the compressed air
drilling fluid. The size of the openings of the ports P and the
vents V may be calculated to produce a desired pressure
differential.
The compressed air flowing through the ports P is directed about
the drill bit B for cleaning and cooling the drill bit B. This flow
cools the cutting edges of the drill bit engaging the formation for
removing the friction generated heat from the cutting edges to
lengthen drill bit life. The cooled and expanded air flow also
cools the formation adjacent the drill bit to freeze the moisture
within the formation to produce an in gage drill hole H. The
formation cuttings produced by the drill bit B moving into the
formation F are removed from the bit B and the drill hole H with
the flowing air circulating from the ports P through an annular
opening formed by the walls of the drill hole H and the outer
surface of the drill string T to the surface G. The viscosity of
air used as a circulating fluid also enables faster penetration of
the drill bit into the formation F.
The compressed air flowing through the vents V is expanded to
further cool the upwardly flowing stream of air and formation
cuttings prior to flowing back to the surface. By maintaining the
temperature of the air flowing upwardly through the annulus below
the freezing point of water, the moisture adjacent the drill hole H
is frozen and the walls are prevented from sloughing off and
falling into the drill hole H. This feature will be greatly
appreciated in drilling through the permafrost of arctic areas. The
driller need only monitor the outlet temperature of the drilling
fluid from the drill hole H with a temperature indicator 17 to
determine that the walls of the drill hole H will remain frozen and
in gage. Should the drilling fluid exit temperature exceed the
freezing temperature of water, the driller may adjust the speed of
the compressor or the valve 12 to reduce the drill hole exit
temperature of the air. Various automatic control systems
regulating the temperature, volume and pressure of the compressed
air may be employed in the use of the present invention.
Anti-freeze injected into the conduit C from reservoir M through
the conduit 30, which may be by capillary action, is used to enable
any moisture within the formation F to be removed from the drill
hole H. Friction generated by the drill bit B boring through the
formation F will melt some moisture in the formation F frozen by
the drilling fluid from the ports P. This moisture will refreeze in
the drill hole H interfering with the circulation of the drilling
fluid unless the anti-freeze is added to enable the moisture to
circulate out of the drill hole H with the reduced pressure air
before refreezing.
The method may also be employed in obtaining formation core samples
by circulating the air through properly sized ports in core sample
cutting tools. The moisture in the core will be frozen in place as
the core is cut by the isothermal expansion of the air providing an
uncontaminated core sample. Cores of arctic permafrost may
therefore be obtained without physical deterioration from melting
or contaminaton of the sample.
The foregoing disclosure and description of the invention are
illustrative and explanatory thereof, and various changes in the
size, shape and materials as well as in the details of the
illustrated construction may be made without departing from the
spirit of the invention.
* * * * *