Note: Descriptions are shown in the official language in which they were submitted.
~;~7~33
FLAPPER TYPE ANNULUS PRESSURE RESPONSI~E
TUBING TESTER VALVE
BACKGROUND OF THE INVENTION
The present invention relates generally to valve
apparatus used in a string of tubing or drill pipe
disposed in a well bore, and particularly to a new and
improved type of tubing tester valve which may be incor-
5 porated in a string of tubing or drill pipe being runinto a well bore and employed to pressure test the
integrity of the string.
Numerous well service operations entail running a
packer into a well bore at the end of a string of tubing
10 or drill pipe, and setting the packer to isolate a pro-
ducing formation or "zone" intersected by the well bore
from the well bore annulus above the packer. After this
isolation procedure, a substance such as a cement slurry,
an acid or other fluid is pumped through the tubing or
15 drill pipe under pressure and into the formation behind
the well bore casing through perforations therethrough
in an area below the packer. One major factor in
ensuring the success of such an operation is to have a
pressure-tight string of tubing or drill pipe.
Another common well service operation in which it
is desirable to assure the pressure integrity of the
string of tubing or drill pipe is the so-called drill
stem test. Briefly, in such a test, a testing string is
- lowered into the well ~o test the production capabili-
ties of the hydrocarbon producing underground formations
or zones intersected by the well bore. The testing is
accomplished by lowering a string of pipe, generally
drill pipe, into the well with a packer attached to the
string at its lower end. Once the test string is
lowered to the desired final position, the packer is set
to seal off the annulus between the test string and the
well casing, and the underground formation is allowed to
produce oil or gas through the test string. As with the
10 previously mentioned well service operations, it is
desirable prior to conducting a drill stem test, to be
able to pressure test the string of drill pipe periodi-
cally so as to determine whether there is any leakage at
the joints between successive stands of pipe.
To accomplish this drill pipe pressure testing, the
pipe string is filled with a fluid and the lowering the
pipe is periodically stopped. When the lowering of the
pipe is stopped, the fluid in the string of drill pipe
is pressurized to determine whether there are any leaks
in the drill pipe above a point near the packer at the
end of the string.
In the past, a number of devices have been used to
test the pressure integrity of the pipe string. In some
instances, a closed formation tester valve included in
the string is used as the valve against which pressure
thereabove in the testing string is applied. In other
instances, a so-called tubing tester valve is employed
~ ~ 7 ~3~
in the string near the packer, and pressure is applied
against the valve elemen~ in the tubing tester valve.
As it is necessary to fill the tubing or drill pipe
string with an incompressible fluid as the string is run
5 into the well bore before applying pressure to the
interior of the string. Some prior art tubing tester
valves, when used in a string without a closed formation
tester valve therebelow, rely upon the upward biasing of
a flapper valve element against a spring by hydrostatic
10 pressure below the tubing tester valve in the test
string to gradually fill the test string from below with
fluid in the well bore, generally drilling "mud." In
other instances, the test string is filled from the top
on the rig floor with diesel oil or other fluids, such a
15 procedure being easily appreciated as time consuming and
hazardous. Still other prior art tubing tester valves
incorporate a closeable bypass port below the valve ele-
ment so that, even with a closed formation tester valve
below, well fluids in the annulus surrounding the test
20 string can enter in the vicinity of the tubing tester
valve and bias a valve element therein to an open posi-
tion through hydrostatic pressure, thereby filling the
string.
At some point during the well service operation, be
25 it cementing, treating or testing, it is necessary to be
able to open ~he tubing tester valve so that flow from
the rig floor down into the formation, which would nor-
~ ~'7~
mally close the valve, may be effected. Prior arttubing tester valves accommodate this necessity in
several ways. Some valves provide for the opening of
the tubing tester valve through reciprocation and/or
5 rotation of the pipe string, while other prior art
valves provide for the opening of the valve through a
valve actuator operated responsive to an increase in
annulus pressure.
The form that the valve element in prior art tubing
10 tester valves may take has also been varied. Ball
valves, flapper valves, and even sleeve valves, where it
is not necessary or desirable to have a fully open bore
from the top of the pipe string to the bottom, have been
employed.
All of the prior art tubing tester valves, however,
have suffered from various deficiencies relating to the
complexity of their operating mechanisms, or from a
necessity to reciprocate or otherwise move the pipe
string in order to open a valve element therein against
20 flow from the surface to a formation below the packer.
SUMMARY OF THE INVENTION
The present invention, in contrast to the prior
art, provides a relatively simple, reliable, annulus
pressure responsive tubing tester valve having applica-
bility to any of the aforementioned well service opera-
25 tions. The tubing tester valve of the present invention
j83
comprises a tubular housing assembly having a downwardlyclosing, spring biased flapper valve disposed therein
near the top thereof. A tubular mandrel assembly is
disposed within the housing assembly below the flapper
5 valve, and is secured to the housing assembly with shear
pins.
When the tubing tester valve of the present inven-
tion is incorporated into a pipe string run into a well
bore, hydrostatic pressure from below the tool will
10 cause the valve flapper to bias upwardly away from its
cooperating valve seat, thereby permitting the pipe
string above the tubing tester valve to become filled
with well bore fluid. As the hydrostatic pressure above
and below the flapper valve e~ualizes, the flapper will
15 again close, thus permitting pressure testing of the
string whenever desired within a few moments of halting
the string's descent into the well bore. In such a
manner, the string can be easily pressure tested after
the attachment of every few stands of pipe, and any leak
in the joints therebetween located and corrected in a
timely manner. As the pipe string reaches the test or
treatment depth in the well bore, the tubing tester
valve of the present invention may be permanently opened
through the application of annulus pressure to the annu-
25 lus surrounding the pipe string from the rig floor.
When pressure is applied to close the valve, theincreased pressure enters the tubular housing assembly
of the tool through a plurality of ports extending
through the wall thereof. This increased pressure acts
on an enlarged portion of the mandrel assembly which
act~ as a piston, due to the inclusion of pressure-tight
5 seals bet~een the housing and mandrel assemblies. When
the applied pressure exceeds the shear strength of the
aforementioned shear pins, the mandrel assembly will
move upwardly in the housing assembly and contact the
valve flappex of the flapper valve assembly, biasing it
10 in a rotational manner upwardly into a position where it
is moved out of the flow path through the tubing tester
valve into a recess in the housing assembly. In order
to assure that the mandrel assembly does not retract
downwardly, thus permitting the flapper valve to
15 reclose, a spring biased locking means is provided to
hold the mandrel assembly in its "up" position. This
locking means comprises, in the preferred embodiment, a
plurality of locking dog segments disposed in cavities
inside the housing assembly, and biased inwardly against
20 the lower portion of the mandrel assembly. When the
mandrel assembly moves to its fully extended upward
position, opening the valve flapper, the locking dog
segments move into an annular recess near the bottom of
- the mandrel assembly and are maintained therein through
25 the biasing actions of surrounding O-rings.
-6a-
The invention relates to an external pressure
actuated tubing tester valve, comprising:
a tubular housiny assembly having a
longitudinal bore therethrough and at least one por-t
extending be-tween said bore and the houslng assembly
exterior;
a valve flapper disposed across the said
bore and hinged to said housing assembly at one side
of said bore; and
a -tubular mandrel slidingly disposed in said
bore below said flapper valve, said mandrel including
a valve actuation section proximate said valve flapper,
a piston sec-tion below said valve actuation section
and extending radially outward therefrom in sliding,
sealing engagemen-t with the interior of said housing
assembly above said ports, and a trailing section of
lesser diameter than said piston section in sliding,
sealing engagement with said housing assembly interior
below said ports.
The invention also relates to a method of
pressure testing a pipe string disposed in a well bore,
comprising:
providing a pipe string having a tubing tester
valve at the lower end thereof;
running said pipe string into said well bore;
filling the interior of said pipe string
- from below with well bore fluid through said tubing
tester valve;
-testing the integrity of said pipe string by
applying pressure -to -the interior of said pipe s-tring
above said tubing tester valve thereagainst;
sealing across the annulus between said pipe
string and -the wall of said well bore below said tubing
tester valve with a packer;
increasing the pressure in the well bore
above said packer; and
~7~ 3
-6b-
opening said -tubing -tester valve, in response
to said pressure increase, to ~low in said pipe string
from above to below said tubing tester valve.
~1~7~ 33
BRIEF DESCRIPTION OF THE DP~AWINGS
Numerous features and advantages of the present
invention will be readily apparent to those of ordinary
skill in the art upon a reading of the following
detailed description of the preferred embodiment of the
5 present invention, taken in conjunction with the accom-
panying drawings, wherein:
FIG. 1 is a schematic illustration of a well test
string for an offshore well in which the tubing tester
valve of the present invention may be disposed.
FIGS. 2A and 2B are half-section vertical eleva-
tions of a prefexred embodiment of the tubing tester
valve of ~he present invention, shown in its initial
position as it would be run into a well bore as part of
a pipe string.
FIGS. 3A and 3B comprise a vertical half-section
elevation of the preferred embodiment of the tubing
tester valve of the present invention depicted in FIG.
2, after the mandrel assembly has been actuated to open
the flapper valve employed therein.
FIG. 4 is a section taken across lines 4-4 in FIG.
3A.
FIG. 5 is a section taken across lines 5-5 i FIG. 3B.
~ ~X683
OVERALL WELL TESTING ENVIRONMENT
Referring to FIG. l of the drawings, a testing
string for use in an offshore oil or gas well is schema-
tically illustrated therein.
In EIG. l, a floating working station 1 is centered
5 over a submerged oil or gas well located in the sea
floor 2 having a well bore 3 which extends from the sea
floor 2 to a submerged formation 5 to be tested. The
well bore 3 is typically lined by steel casing 4
cemented into place. A subsea conduit 6 extends from
10 the deck 7 of the floating work station l into a well
head installation 10. The floating work station 1 has a
derrick 8 and a hoisting apparatus 9 for raising and
lowering tools to drill, test, and complete the oil or
gas well. A testing string 14 is being lowered into the
15 well bore 3 of the oil or gas well. The testing string
includes such tools as one or more pressure balanced
slip joints 15 to compensate for the wave action of the
floating work station 1 as the testing string is being
lowered into place, a circulation valve 16, a tubing
20 tester valve 17 of the present invention, a formation
tester valve 18, and a sampler valve l9.
The slip ~oint 15 may be similar to that described
in U.S. Patent No. 3,354,950 to Hyde. The circulation
valve 16 is preferably of the annulus pressure respon-
sive type and may be as described in U.S. Patent Nos.
' , ` '
- ' ' .
~ 3
3,850,250 or 3,970,147. The circulation valve 16 may
also be of the recloseable type described in U.S. Patent
No. 4,113,012 to Evans et al.
The tester valve 18 i5 pre~erably o~ the annulus
5 pressure responsive type, and being further described
as the type with the capability to be run into the well
bore in an open position. Such valves are known in the
art, and are described in U.S. Patent ~o. 4,~55,288,
assl-gned to the assignee of the present invention, and
10 issued ~pril 17, 1987.
The sampler valve 19 is preferable of the annulus
pressure responsive type having a ~ull open bore
therethrough, as d~scribed in U.S. Patent No. 4,665,983,
assigned to the assignee of -the present invention, and
15 issued May 19,1987.
As shown in FIG. 1, the circulation valve 16,
tubing tester valve 17, formation tester valve 18, and
sampler valve 19, are operated by fluid annulus pressure
exerted by a pump 11 on the deck o the floating work
20 station 1. Pressure changes are transmitted by pipe 12
to the well annulus 13 between the casing 4 and the
testing string 14. Well annulus pressure is isolated
from the formation 5 to be ~ested by a packer 21 having
expandable sealing element 22 thereabout set in the well
25 casing 4 just above the formation 5. The packer 21 may
be a Baker Oil Tools Model D packer, the otis
Engineering Corporation Type W packer, the Halliburton
, ~ .
~7~33
--10--
Services EZ Drill~ SV, RTTS or CHAMP~ packers or other
packers well known in the well testing art.
The testing string 14 may also include a tubing
seal assembly 20 at the lower end of the testing string
which "stings" into or s~abs through a passageway
through packer 21 if such is a production packer set
prior to running testing string 14 into the well bsre.
Tubing seal assembly 20 forms a seal with packer 21 iso-
- lating the well annulus 13 above the packer from an
interior bore portion 1000 of the well immediately adja-
cent the ~ormation 5 and below the packer 21~
Check valve 20 relieves pressure built up in
testing string 14 as seal assembly 21 stabs into packer
22.
A perforating gun 1005 may be run via wireline or
may be disposed on a tubing string at the lower end of
testing string 14 to form perforations 1003 in casing 4,
thereby allowing formation fluids to flow from the for-
mation 5 into the flow passage of the testing string 14
via perforations 1003. Alternatively, the casing 4 may
have been perforated prior to running test string 14
into the well bore 3.
As previously noted, the tubing tester valve of the
present invention may be used to pressure test string 14
as it is lowered into the well. As test depth is
reached, pressure in annulus 13 is increased by pump 11
through Fonduit 12, whereupon tubing tester valve 17 is
.:
, . :
~.~7~ 33
locked into an open position.
A formation test controlling the flow of fluid from
the formation 5 through the flow channel in the testing
string 14 may then be conducted by applying and
releasing fluid annulus pressure to the well annulus 13
by pump 11 to operate circulation valve 16, formation
tester valve 18 and sampler valve 19, accompanied by
measurin~ of the pressure buildup curves and fluid tem-
perature curves with appropriate pressure and tem-
perature sensors in the testing string 14, all as fullydescribed in the aforementioned patents.
It should be understood, as noted previously, that
the tubing tester valve of the present invention is not
limited to use in a testing string as shown in FIG. 1,
or even to use in well testing per se. For example, the
tubing tester valve of the present invention may be
employed in a drill stem test wherein no other valves,
or fewer valves than are shown in FIG. 1, are employed.
In fact, the valve of the present invention may be
employed in a test wherein all pressure shut-offs are
conducted on the surface at the rig floor, and no
"formation tester" valves are used at all. Similarly,
in a cementing, acidizing, fracturing or other well ser-
vice operation, the tubing tester valve of the present
invention may be employed whenever it is necessary or
desirable to assure the pressure integrity of a string
of tubing or drill pipe.
.
~. . . ' ' ' ' ' ' ', '.
.
.~: - . .
' ' : '' .
7~i8
-12-
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Tubing tester valve 17 of the preferred embodiment
of the present invention generally comprises a tubular
housing assembly 100 surrounding a tubular mandrel 102.
The top of housing assembly 100 comprises valve
case 110, having a cylindrical exterior 112. At the
upper end of valve case 110, entry bore 114 having
threaded wall 116 provides a means by which a string of
tubing or drill pipe may be secured to the top of tubing
tester valve 17. Below threaded wall 116, frustoconical
surface 118 leads to cylindrical entry bore 120, below
which outwardly beveled annular edge 122 extends to a
larger mandrel receptacle bore 124. Below bore 124,
downwardly and outwardly extending frustoconical surface
126 leads to cylindrical valve flapper bore 128, bore
15 128 extending to the bottom of valve housing 110, where
valve case 110 is secured to valve support housing 130
at threaded connection 132. Valve support housing 130
extends upwardly into bore 128 of case 110 in a
telescoping manner. Valve flapper 136 of circular con-
20 figuration is disposed in a recess 138 (see FIG. 3A) atthe top of valve support housing 130. Valve flapper 136
possesses two laterally extending legs 140, which, with
pin 142 extending therethrough and through upright pin
: support 143 at the top of valve support housing 130,
25 form a hinge assembly 145 permitting valve flapper 136
to rotate upwardly into valve chamber 144 (see FIG. 3A)
~'7~
-13-
defined by bore wall 128. Valve flapper 136 is normally
biased in a rotationally downward direction by a spring
137, as is generally known in the art.
In its normally closed or downwardly biased posi-
tion, valve flapper 136 rests against ring-shaped valve
seat 146, the top annular edge 148 of which provides a
surface ~or the lower surface 150 of valve flapper 136
to seal against. Valve seat 14S is disposed in valve
seat bore 152 near the top of valve support housing 130,
and is supported from below by annular shoulder 154.
A plurality of radially oriented threaded holes 156
extend through the wall of valve support housing 130
between valve seat bore 152 and cylindrical exterior
leading surface 158 above seal assembly 160 disposed
about valve seat 146 in bore 152. Allen screws (not
shown) threaded into holes 156 bear against valve seat
146 and keep same from being pumped or sucked out of
valve support housing 130 when valve flapper opens.
Another seal assembly 162 seals between the exterior of
valve support housing 130 disposed inside of housing
110, and bore wall 128 of housing 110.
Below the connection 132, ~alve support housing 130
possesses a generally cylindrical surface 166 which
extends to the lower end thereof. On the interior of
valve support housing 130, mandrel orientation bore 168
extends downwardly below shoulder 152, stepping to a
larger, lower bore 170 at step 172. At the same side of
'' .
.~., . . ~
,
-14-
mandrel orientation bore 168 as the valve flapper hinge
assambly is located, longitudinally extending key 174
protrudes radially inwardly from the wall of mandrel
orientation bore 168.
Below enlarged bore-170, beveled annular surface
176 extends outwardly to cylindrical piston bore 178,
which in turn extends downwardly to slightly outwardly
tapered surface 180 and cylindrical locking assembly
bore 1820 A plurality of radially oriented pressure
ports 184 extend through the wall of valve support
housing 130 immediately below tapered bore 180.
Lower adapter 190 is secured at threaded connection
188 to valve support housing 130. The lower exterior
192 of lower adapter 190 is generally of cylindrical
configuration, and extends to the lower end of lower
adapter 190 whereat radially inwardly extending shoulder
194 leads to seal recess 196, below which extend male
threads 198 by which additional components may be added
to the pipe string below tubing tester valve 17 of the
present invention. A seal assembly (not shown) may be
disposed in recess 196 to assure a fluid-tight seal be-
tween tubing tester valve 17 and the next lower com-
ponent.
The upper portion 200 of lower adapter 190 is
received inside of valve support housing 130, and inclu-
des a plurality of shear pin holes 202, the outer
extents of which are intersected by a circumferential
groove (unnumbered). Below holes 202, a plurality of
circumferential windows 206 extend through the wall of
lower adapter 190, windows 206 having webs 208 extending
therebetween, webs 208 having segmented annular channel
210 on their exteriors ~see FIG. 5).
The upper portion 200 of lower adapter 190
possesses an enlarged shear pin bore 212, which necks
down slightly to lower mandxel bore 214, which ter-
minates at tapered shoulder 216 leading to exit bore
21~.
Tubular mandrel 102 includes several distinct sec-
tions, the first being relatively thin-walled valve
actuation section 220 at the top thereof. Section 220
is of slightly lesser outer diameter than valve orien-
tation bore 168, and its upper end is defined by arcuateedge 222, running from its highest extent diametrically
opposite to the flapper hinge assembly 145, and curving
downward to its lowest extent on the same side of the
tool as the hinge assembly 145. A longitudinally
20 extending slot 224 is cut through the wall of section
220 in order to accommodate key 174 extending inwardly
thereinto from mandrel orientation bore 168, thus pre-
venting rotation of mandrel 102 with respect to housing
assembly 100~
At the lower extent of valve actuation section 220,
mandrei piston section 230 extends outwardly therefrom.
It should be understood that the inner diameter 226 of
~7~ 33
-16-
mandrel 102 is constant from the top thereof until it
reaches flared exit bore 228 at the very bottom thereof.
On the other hand, the outer diameter of piston section
230 is defined by leading beveled surface 232, ter-
5 minating at cylindrical step 234, which is in turnfollowed by chamfered annular edge 236~ Below edge 236,
cylindrical piston seal surface 238 extends downwardly
to inwardly chamfered edge 240, trailing piston surface
242, and downwardly facing annular shoulder 244, ter-
10 minating in shear pin step 246. Below shear pin step246, trailing cylindrical surface 248 of slightly lesser
diameter extends downwardly to the lower end of mandrel
102. Extended circumferential annular locking groove
250 cut in surface 248 lies neax the lower end of
15 mandrel 102, below which seal assembly 252 is disposed
in a recess ~unnumbered) in surface 248 to form a
sliding, pressure-tight seal between mandrel 102 and
lower adapter 190.
Returning to the upper end of piston section 230,
seal assembly 254 disposed in a circumferential groove
(unnumbered) in piston seal surface 238 provides a
sliding, pressure tight seal between mandrel 102 and
valve support housing 130.
A piston cavity 256 of variable volume is defined
between the inside of valve support housing 130 and the
outside of mandrel 102 above piston section 230. This
cavity shortens as mandrel 102 moves upwardly in housing
~ ;~'7;~83
assembly 100, and fluid in cavity 256 is expelled into
bore 260 of mandrel 102 through apertures 258 during
such movement.
Referring again to FIG. 2B, a plurality of shear
pins 270 are disposed in holes 202 in upper portion 200
of lower adapter 190, ex~ending into matching circum-
ferential shear pin groove 262 in the ext~rior of
mandrel 102 through shear pin step 246. Shear pins 270
are maintained in place by o-ring 272. With shear pins
270 in place, upper portion 200 of lower adapter 190
abuts downwardly facing annular shoulder 244 on mandrel
102.
A plurality of locking dogs 280, of generally
trapezoidal cross-section, are disposed in windows 206
in lower adapter 190. Locking dogs 280 have several
lateral grooves 282 cut in their eXteriors, while their
interior surfaces 284 are of arcuate configuration and
of substantially the same radius as the bottom of
locking groove 250. O-rings or garter springs 286 are
disposed in the locking dog grooves 282 and extend about
mandrel 102 on the exterior of webs 208, residing in
channels 210 (O-rings/springs 284 not shown in FIG. 5),
whereby a strong radially inward force is exerted upon
locking dogs 280.
-18-
~ OPERATION OF THE PREFERRED EMBODIMENT
. .
Referring again to FIG. 2-5, tubing tester valve 17
of the present invention is run into a well bore as part
of a testing or other pipe string~ As tubing tester
valve 17 is run in, it is in the position shown in FIGS.
2A and 2B, with valve flapper 136 resting on seat 146,
mandrel 102 being in its retracted position with upper
section 220 thereof below valve flapper 136.
As the pipe string continues into the well bore
with the addition of more stands, the hydrostatic
10 pressure of well bore fluid which has entered the open
end of the pipe string will overcome the spring bias of
valve flapper, opening it and thereby filling the pipe
string thereabove until the hydrostatic head above valve
flapper 136, in conjunction with the force of the
flapper spring, approximates the hydrostatic pressure
below valve flapper 136, whereupon it will again close
and seat on top edge 148 of valve seat 146
In such a manner, the pipe string above valve 17
can be pressure tested every few pipe stands to ascer-
taîn the presence of any leaks and remedy them withoutpulling dozens, or even hundreds, of stands out of the
hole af ter reaching test or treatment depth.
- When the pipe string has been run to its final
depth to conduct a well service operation and a packer
set or.stabbed into therebelow, valve flapper 136 can be
permanently opened and locked open so as to permit
~7~
--19--
pumping down the pipe string, by applying pressure to
the well bore annulus surrounding the pipe string. The
increased pressure will enter tubing tester valve 17
through ports 184 in housing assembly 100, and act on
the underside of piston section 230 of mandrel 102 on a
cross-sectional area defined between trailing surface
248 of mandrel 102 and piston bore 178. Since the set
packer seals off the well bore below the packer, and
thus the bottom of the pipe string from the pressure
increase, hydrostatic acts on the inside of the tool
and thus downwardly against piston section 230 of
mandrel 102 through apertures 258. Thus, shear pins 270
are assistéd by the hydrostatic and do not have to be
made overly strong, as would be the case if chamber 256
15 was at atmospheric ~pressure) as in some prior art
pressure-actuated shear pin type tools. When the
pressure overcomes the shear strength of shear pins 270,
mandrel 102 will move upward relative to housing
assembly 100, arcuate edge 222 at the top of valve
action section 220 contacting valve flapper 136 on its
underside 150 at a point diametrically opposite hinge
assembly 145 so as to provide the maximum possible ini-
tial opening moment against valve flapper 136.
As mandrel 102 continues its relative upward move-
25 ment, valve flapper 136 will continue to ride on arcuate
edge 222 as it rotated open into valve chamber 144 until
it is substantially vertical, whereupon mandrel 102 con-
i8
-20-
~ tinues upward past opened valve flapper 136 and into
mandrel receptacle bore 124 (see FIG. 3A).
When mandrel 102 reaches the upper limit of its
travel as restricted by contact of piston section 230
with annular surface 176 above piston bore 178, locking
groove 250 is adjacent inwardly-biased locking dogs 280,
which fall into groove 250 and are maintained therein by
springs or o-rings 286 (see FIG. 3B). The trapezoidal
shape of locking dogs 286, in conjunction with the
undercut top edge 251 of locking groove 250, prevents
locking dogs 280 from jumping out of groove 250 upon any
application of downward force to mandrel 102, thus
ensuring the locked-open position of valve flapper 136
as shown in FIG. 3A and permitting the pumping of fluids
downwardly thereby without risk of flapper closure.
From the foregoing description of the preferred
embodiment and its operation, it will be readily
apparent to those of ordinary skill in the art that the
tubing tester valve of the present invention constitutes
20 a novel and unobvious solution to problems unsolved by
the prior art and possessing many advantages thereover.
For example, the present invention allows for safer
running of testing tools and pipe, due to the relatively
balanced pressures inside and outside the string, ren-
25 dering it impossible for the pipe to ~U~tube" or losethe hydrostatic pressure of the mud on the f,ormation, as
might be experienced with an empty or highly under-
. , .
~:7~83
-21-
balanced string. This is particularly critical when no
downhole formation tester valves are employed, as the
formation blow out through the pipe string. In addi-
tion, the tool of the present invention can be placed
immediately above the tubing seal assembly (see FIG. 1
and description thereof) to allow internal pressure
testing of all tools, including downhole gauge carriers
in the string, while running in. Rig time is also
saved, as previously noted, by permitting continual
testing of the pipe string during run-in, for early
detection and easy remedying of leaks. The automatic
filling of the pipe string through the tubing tester
valve of the present invention saves time, as well as
the handling of diesel or other fluid on the rig floor
required when filling a string from the top. The pre-
sent invention is of a relatively simple design, easy to
prepare for operation and the use of a flapper valve
instead of a ball valve ensures greater reliability for
the applications in which the tool is employed, and
easy, inexpensive replacement of the valve flapper and
seat should that be necessary.
While the tubing tester valve of the present inven-
tion has been described in terms of a preferred embodi-
ment, numerous additions, deletions and modifications
thereto can be made without departing from the spirit
and scope of the claimed invention.
: