Note: Descriptions are shown in the official language in which they were submitted.
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R. R. V~NN -
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SUMMARY OF THE INVENTION
Method and apparatus for measuring downhole pressure
while simul-taneously perfora-ting a cased borehole. The method of
the present invention is carried out by supporting a casing perfo-
ratlng gun on the end of a string of production tubing and posi-
tioning the gun downhole adjacent to a hydrocarbon containing
formation. The gun device includes a gun firing head associated
therewi-th by which the charges of -the gun are detonated when the
gun firing head is actuated. An apparatus for actuating the gun
firing head is connected to the lower end of a capillary tubing and
the tubing is stored in wound-up configuration on a reel. The
upper end of -the capillary tubing is connected to a source of fluid
pressure. The lower end of the capillary tubing is opened to flow
into -the borehole in proximity of the apparatus for actuating the
gun firing head. The pressure and rate of flow into the capillary
tubing is measured at the surface of the earth, thereby enabling
the downhole pressure at the outlet end of the tubing to be calcu-
lated or measured. The capillary tubing is manipulated to cause
cooperative action with respect to the gun and apparatus for
actuating the gun firing head, whereupon -the gun firing head causes
the charges of the perforating gun to be det~nated, thereby perfo-
rating the casing and completing the well. Hydrocarbons flow from
the formation, into the casing perforations, up in-to the production
-tubing, and to the surface of the ground, while the bo-ttomhole
~5 pressure is measured from the surface of -the ground.
In one form of the invention, -the gun firing head is re- ~
sponsive to impact. The apparatus for actuating the g-m firing head
is an elonga-ted bar which is dropped or impacted against the gun
firing head by controlling the ra-te at which the bar is lowered into
the borehole on the end of the capillary tubing.
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R. R. VANN . ~2~
In another form of the invention, the apparatus for
actuating the gun head has a latch means by which the apparatus is
latched onto the gun firing head so that an upward force exerted
upon the capillary actuates the gun firing head and detonates the
S charges of the gun.
Accordingly, a primary object of the present invention
is the provision of method and apparatus by which a wellbore casing
can be perforated while simultaneously the downhole pressure is
monitored by utilizing some of the apparatus which is employed for
firing the gun.
Another object of the present invention is the provision
of method and appara-tus for comple-ting a downhole fluid bearing
formation while simultaneously recording the downhole pressure
thereof.
A further object of the present inven-tion is the provi-
sion of well completion apparatus by which a casing is perforated
while the downhole pressure effec-ted by the production formation is
monitored from the surface of the ground.
Ano-ther and still further object of the present invention
is the provision of a small conduit stored upon a drum and which
supports an apparatus for actuating a gun firing head in such a
manner that when the apparatus has been lowered into contact with
-the gun firing head, a jet perforating gun is discharged while
simul-taneousIy the downhole pressure at the gun is sensed from -the
25~ surface of the earth by measuring the flow rate and pressure of a
fluid flowing through the upper end of the capillary tubing.
These and other objects of the present invention will
become readily apparent to those skilled in the art upon reading
the following detailed description and clai~s and by referring to
the accompanying drawings.
R. R. VANN ; ~ ~ Z~ ~ 44
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The above objects are attained in accordance with the
present invention by the provision of a method for use with appara-
tus fabricated in a manner substantially as des'cribed in the above
abstract and summary.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a part diagrammatical, part schematical,
broken, part cross-sectional view of a borehole having apparatus
made in accordance with the present invention associated therewith;
Figure 2 is a cross-sectional view taken along line 2-2
of Figure l;
Figure 3 is an isolated, fragmentary view of a modifica-
-~ion of part of -the apparatus disclosed in Figure l;
Figure 4 is a schematical representa-tion of a simplifi-
cation of Figure l; and,
Figure 5 is an enlarged, broken, part cross-sectional
view of part of the apparatus seen disclosed in Figures 1-4.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In Figure 1, there is disclosed a wellhead 10 of con-
ventional design having a lubricator 12 affixed to the upper
terminal end thereof. A casing 14 extends downhole through a
hydrocarbon containing formation 16. A production tubing string
18 is concentrically arranged respective to the casing and
extends downhole into the wellbore.
A packer apparatus 20 divides the annulus between the
tubing and casing into an upper annulus 22 and a lower annulus
24, A vent assembly 26 is connected in series relationship re-
spective to the tubing an~ is positioned in underlying relation-
ship respective to the packer. The vent assembly preferably is
made in accordance with ~nited States Patents Nos. 3,871,448;
3,931,855; 4,040,485; and 4,151,880.
A casing gun 28 is connected to the lower end of the
tubing striny. An example of a suitable casing gun is set forth
in United States Patents Nos. 3,706,344i 3,717,095; and 3,717,099.
The casing gun preferably includes a gun firing head 30 to which
. there is connected apparatus 32 for detonating the charges 34 of
the gun when the apparatus 32 is impacted with ~ufficient force.
A capillary tubing 36 has a lower outlet end connected
to an outlet pipe 38. An elongated bar 40 includes a fishing
neck 42 at the upper end thereof. The outlet pipe is affixed to
the fishing neck so that the capillary tube can support and
manipulate the bar.
The capillary tube is stored in a wound up configuration
on drum 44. The drum is similar to a slick line drum, and is
supported in journaled relationship respective to a suitable
frame 46. Recorder device 48 is connected to receive a pressure
signal from flow line 50, which in turn is connected to a tee
52. Flow line
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R. R. VANN ,
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54 is connected to a swivel 56 which in turn is connected to the
upper or inlet end of -the capillary tubing 36.
A pressure regulator 58 is connected t~ a source of fluid
under pressure. Flow line 60 connects tee 52 to the regulator 58.
Flow rate measuring device 49 measures the rate of flow through the
capillary and is connected to relay the flow rate da-ta signal to
the recorder 48.
As seen in Figure 5, the outlet ports 62 are formed
radially within the wall of outlet pipe 38. The lower end of the
outlet pipe is rigidly affixed to the fishing neck of the actuating
bar 40. The capillary is rigidly affixed at 66 to the upper
marginal end of the outlet pipe, with the outlet end 70 of -the
capillary freely flowing in-to the interior 72 of the outlet pipe.
As seen in Figure 1, the casing and production tubing,
respec-tively, are connected to outflow pipes 74 and 76, respecti~e-
ly. The vent assembly preferably is provided with por-ts 78 so that
when the vent assembly is moved to the opened position, flow can
occur from annulus 24, through por-t 78, and into the interior 80 of
the production tubing.
In Figure 3, the lower end of bar 40 is provided with a
non-releasable clamp 240 which engages -the fishing neck 132 when
the bar is lowered thereagainst. The capillary lifts the bar 40,
which lifts the fishing neck 132, in order to actuate the gun
firing head and detonate the shaped charges of the gun due to -the
upward movement of the neck 132.
In opera-tion, the casing gun is attached to the lower end
of a tubing string and run downhole into the borehole so that the
gun is placed adjacent to the formation to be completed. The
packer is set and the vent assembly moved to the opened position.
A lubricator is placed at the upper end o~ the casing, the bar 4
R. R~ VANN ~ ~ ~22~44
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is lowered through the lubrica-tor by rotating -the dru~ 44 until the
bar is brought into close proximity to the ~iring head of the gun.
Pressure regulator 58 is adjusted to a value to provide
a suitable flow at 62, with the flow rate and pressure being re-
corded at 4a. This data subsequently enables calculation of the
downhole pressure effected at the outlet end of the capillary.
Alternatively, the recorder 48 can be provided with circuitry for
integrating the two signals at 49 and 50 so that a direct pressure
reading is obtained.
The initial pressure reading is the hydrostatic head of
any fluid column that may have been placed within the tubing string
and above the gun firing head as a result of opening of the vent
assembly ports, or that may have been placed within the tubing
s-tring as a cushion.
lS The bar 40 is manipulated by the capillary tu4ing by
rotating drum 44, causing -the bar 40 to impac-t against actuator
device 32 of Figure 1, thereby actuating the gun firing head and
de-tonating the shaped charges of the gun. This action forms perfo-
rations 67 in -the casing while tunnels 68 are fo~med as the result
of the jet of hot gases. The production fluid from the formation
flows -through the perforation 67, up through the lower annulus 24,
and into the port 78 of the ven-t assembly, where the produced fluid
continues to flow up through the tubing string at 80 and out of the
wellhead at 7~, where the produced fluid is flowed to a pit while
the wellbore is being cleaned. During -this time~ -the recorder 48
continually monitors the downhole pressure,
After the well has been cleaned up and there is no danger
of contaminating the formation, the well is shut-in by closing the
valve at 76, and the downhole pressure measured over an ex-tended
interval of time.
R. R. VANN ~2224~
The bar 40 can subsequently be retrieved, the lubricator
removed from the top of the wellbore, and the well connected into
a gathering sys-tem. The data obtained from the foregoing method
enables the size of the reservoir and the quantity of hydrocarbons
contained therewithin to be calculated.
In the embodiment of Figure 3, where~er it is deemed de-
sirable to do so, the bar 40 can be latched onto the actuator 132
of the gun firing head, thereby procluding any up thrust of the bar
from inad~er-tently occurring. The gun is detonated by placing the
capillary tubing in tension, so that the actuator is moved uphole,
causing the gun firing head to be actuated and -the charges of the
gun detonated.
It is considered within the comprehension of this inven-
tion to utilize other types of perforating guns, including through
tubing guns. It is furthermore considered within the comprehension
of this invention to detonate the gun by utilizing other gun firing
mechanisms, as shown for example in the abo~e mentioned issued
paten*s.
The fluid pressure source S can be an inert gas such as
nitrogen, helium, or flue gases. Furthermore, the fluid can be a
liqui.d such as water or a hydrocarbon. Hence, the fluid flow from
S can be a compressible or non-compressible fluid.
The capil:lary -tubing 36 preferably is a high strength,
corrosion resis-tant alloy which will endure the deleterious effects
of the downhole fluids; and, which has sufficien-t tensile strength
to support the bar 40 as well as the weight of -the thousands of
feet of the -tubing itself. ~ tubing outside diameter of 0.089 to
0.125 inches is suitable, for example, a capillary tubing 0.089
outside diameter with a 0.054 inside diameter.
R. R. VANN
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There are many wells which cannot be monitored by sending
a package of instruments downhole to proximity of the payzone be-
cause of excessively high temperatures and pressures. The instru-
ment package will not endure temperatures of 600F, for example.
The present invention can be advantageously employed for measuring
the bot-tom hole pressure of such high ternperature formations.
There is available high temperature explosive material
from which the shaped charges can be made. This substance is known
as H.N.S. and is commercially available. There also is available
high -temperature prima cord and initiators, or blasting caps, which
will endure temperature of 600F. Hence, the s-tate of the art pro-
vides the explosives necessary for the practice of this invention.
Example: 8500 feet of 0.089 o.d. and O.QS4 i.d. steel alloy
tubing 36 was wound on a slick line reel 44 and connected to a regu-
lated source of compressible fluid. A valve means and a dead-weight -
pressure measuring apparatus was connected at the outle-t end of tubing
36 to simulate downhole conditions. The recorder 48 was calibrated
for -the pressure ranges anticipated for the subsequently encountered
downhole conditions.
2~ The apparatus of Figure 1 was installed in the borehole,
and the well was then completed using the illustra-ted completion ap-
paratus. The flow conditions at 49 and 50 were recorded during com-
pletion of the well. The well was shut-in and the bo-ttom hole shut-,
in pressure recorded until the forma-tion pressure reached equili-
brium. The recorded data was correla-ted with the calibration curves
-to ob-tain the true bot-tom hole pressure data.
The above described system enables a well to be completed and the
potential of a payzone to be determined by making a single trip into the borehole
with the sm~ll tubing. The data recorded during the well completion
technique provides downhole information which has heretofore been unavailable.
TheJnethod of-the present invention enables the dcwnhole conditions in a high
temperature borehole to be evaluated within arnuch shorter time interval than wæ
heretofore possible.
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