Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF THE INVENTION
3 This invention relates generally to drill stem testing
4 tools, and particularly to a new and improved full bore sampler
and safety valve apparatus for trapping a flowing sample of
6 formation fluids that may be produced from an isolated well
7 intervalO
9 BACKGROUND OF THE INVENTION
A drill stem test may be considered to be a temporary
ll completion of an earth formation that has been intersected by a
12 well bore. A packer is run into the well on a pipe string and is
13 set to isolaté the interval of the well bore to be tested, and
14 then a test valve is opened to permit fluids in the formation to
flow into the bore hole and up into the pipe string to obtain an
16 indication of the commercial potential of the well. Pressure
17 data is recorded with the test interval open and then shut in,
18 from which many useful parameters such as permeability and ini-
l9 tial reservoir pressure can be determined. It also is desirable
to collect an actual sample of the fluids for subsequent labora-
21 tory analysis.
22 A sampler that has been used for many years with great
23 success is disclosed in Nutter U.S. Patent No. 3,308,887, as-
24 signed to the assignee of this invention. As shown in Figure 3B
of this patent, the flow of formation fluid is routed through an
26 annular chamber having sleeve valves at each end that simulta-
27 neously can be opened and closed. When the valves finally are
28 closed at the end of the test, a flowing sample of ~he fluid
29 being produced is entrapped at formation conditions of tempera-
ture and pressure. However, the testing apparatus shown in the
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1 Nutter patent has a barrler that blocks vertical access through
2 the tool and which must be removed before other equipment such as
3 a pressure recorder or a perforator can be run into the well.
4 A sampler valve that uses a pair of vertically spaced ball
valves to simultaneously open and close the respective ends of a
6 sample chamber is shown in U.S. Patent No. 4,063,593. The
7 device shown in this patent, while being full-bore, is considered
8 to be unduly complicated and thus subject to malfunction in use
9 in the well.
It is the general object of the present invention to provide
11 a new and improved full-bore sampler valve ~or trapping the last
12 flowing sample of formation fluids that are produced during a
13 drill stem test.
14 Another object of the present invention is to provide a new
and Lmproved full-bore sampler apparatus that can be closed
16 responsive to a specific annulus pressure signal to trap a sample
17 and to also function as a safety valve when closed to shut in the
18 formation being tested.
19 '
29 S~M~RY OF THE INVENTION
21 These and other objects are attained in accordance with the
22 concepts of the present invention through the provision of a
23 sampler valve apparatus comprising a housing having an axially
2~ shiftable actuator mandrel that carries spaced ball valve ele-
ments that when open present an unobstructed vertical passage and
26 when closed block the open ends of a sample chamber for contain-
27 ing a discrete volume of formation fluids. The actuator mandrel
28 carries a piston that is sealingly slidable within a cylinder
29 formed on the housing, with opposite sides of the piston ini-
tially being subject to atmospheric or other low but equal
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pressures. In response to a predetern~ined increase in the pressure oE
fluids in the well annulus outside the housing, a passageway leading to
one side of the piston is opened so that well fluids at hydros-tatic
pressure can act one one side of the piston to force the actuator mandrel
to shift axially of the housing and to cause the ball valves to be rotated
simultaneously to their closed positions. In accordance with another
feature of the present invention, the axial vement of the ac-tuator m~ndrel
can be employed to open a valve that functions to communicate the well
annulus with an associated valve such as a reverse circulating valve to
enable the same to be operated by subsequent changes in the pressures of
fluids in the well annulus.
Thus, in accordance with one broad aspect of the invention,
there is provided apparatus adapted for use in closing the bore of a pipe
string during a~elltesting operation comprising: a housing having an
actuator mandrel assembly slidably disposed therein, said housing and
mandrel assembly defining a flow passage; axially spaced full-opening va.Lve
means mounted on said mandrel assembly for opening said flow passage in one
longitudinal position of said mandrel assembly within said housing and
for closing said flow passage in another longitudinal position -therein;
hydraulically operable means on said mandrel assembly normally s~ject to
balanced pressures for shifting said mandrel assembly from said one position
to said other posi-tion; and means responsive to a predetermined pressure of
fluids in the well annulus surrounding sald housing for subjec-ting said
hydraulically operable means to well annulus pressure to cause shifting
of said mandrel assembly to said other position and closure of said flow
passage by s id valve ne ns, a region of sald flow passaye located ~et~en
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said valve m,eans defining a sample chamber adapted to trap a flowing sample
of formation fluids.
In accordance with another broad aspect of the invention there is
pxovided---valve apparatus adapted for use in a well testing operation to
close the bore of a pipe string and to trap a sample of fo.rn~tion fluids
in response to -the ap~lication of a predetermined pressure to fluids stand-
ing in the well annulus, comprising: a housing having means'at its ends for
connecting the same in the pipe string; an actuator mandrel asse~bly slid-
ably disposed in said housing, said assembly and housing defining a flcw
passage; upper and lower ball valve elements rotatably mounted on said
mandrel assembly for providing a full-opening bore through said apparatus
when said mandrel assembly is in a lower position within said housing and
for simultaneously closing said flow passage when said mandrel assembly
is shifted to an upper position within said housing, said valve elements
when closed defining walls of a sample chamber that is located in part in
the bore of said mandrel assembly be,tween said valve elements; cylinder
means in said housing; piston means on said mandrel assembly sealingly en-
gaging said cylinder meansi seal means on said housing and mandrel assembly
above and below said piston means and having substanially the same diameter
of sealing engagement to provide variable capacity chambers initially at
atn~ospheric or other low pressure located above and below said piston means;
port means leading from the lower one of said variable capacity chambers
to the exterior of said housing; and rupture disc means normally closing
said port means and responsive to a p,redetermined pressure differential for
admitting well annulus fluids into said lower variable capacity chamber
whereby the pressure of said fluids can act on the lower face of said piston
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means to shif-t said mandrel assembly upwardly to said upper position and
cause closure of said ball valve elemen-ts.
B~IEF DESCRI~TION OF T~E DP~NGS
The present invention has o-ther objects, feat~.es and advantages
that will become more clearly apparent in connection with the following
detailed descrip-tion of a preferred emkodiment, taken in conjunc-tion with
the appended drawings in which:
Figure 1 is a schematic view of a s-tring of drill stem testing
tools positioned in a well being tested;
Figures 2A and 2C are longitudinal sectional views, with portions
in side elevation, of a full bore s 9 1er and safety valve constructed in
accordance with the principles of the present invention;
Figure 3 is a fragmentary cross-section view taken along lines
3--3 of Figure 2B;
Figure 4 is an enlarged sectional view of the rupture disc
assembly,
Figure 5 is a cross-section taken along line 5~-5 of Figure 2B;
and
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1 Fig. 6 is a fragmerltary CrOsS-sectional view -ta~ell on lirl~s
2 6--6 o~ Figs. 2A and 2B.
4 DESCRIPTION OF A PREFERRED EMBODIMENT
Referring initially to Fig. 1, there is shown schematically
6 a string of drill stem testing tools suspended withill the well
7 casing 10 on drill pipe 11. The tools comprise a hook wall-type
8 packer 12 that functions to isolate the well interval to be
9 tested from the hydrostatic head of fluids thereabove, and a main
10 test valve assembly 13 that functions to permit or terminate the
11 flow of orm tion fluids from the isolated interval. The test
12 v~lve 13 preferably is of a type that may be opened and closed in
13 response to changes in the pressures of fluids in the annu:Lus
14 between the pipe 11 and the casing 10. The valve assembly 13 is
lS well known and is covered by U.S. Patent No. RE 29,638 also
16 assigrled to'the assignee of the present invention.
11
18 Other equipment componenets such as a jar and a safety joint may
19 be employed in the string of tools but are not illustrated in the
~0 drawings. A per~orated tail pipe 14 may be connected to the
21 lower end of the mandrel of the packe~ 12 to enable fluids in the
22 well bore to enter the tools, and typical pressure recorders 15
~3 are provided for the acquisition o~ pressure data during the
24 test.
A full-bore sa~npler safety valve 20 that is constructed in
26 accordance with the principles of the present lnvention is
27 connected in the pipe string just above the main test valve
28 assembly 13. As shown in detail in Figs~ 2A2C, the valve as~
29 sembly 20 includes a tubular housing 25 that has threads 26 at
each end for connecting the same within the tool string. The
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1 housing 25 may include several sections that are threaded to-
2 gether such as an upper sub 27, a sampler sub 28, a cylinder sub
3 29 and a lower sub 30. Upper and lower vertically spaced ball
4 valve assemblies 32 and 33 are rotatably mounted on an elongated
actuator mandrel 34 that is axially slidable within the housing
6 25 between a lower position as shown in the drawings where the
7 ball valves are open, and an upper position where the valves
8 simultaneously are rotated closed. When the valves 32 and 33 are
9 closed, the region 35 therebetween and areas outside the mandrel
provide a sample chamber fox entrapping a discrete volume of
11 formation fluid.
12 ~s shown in Fig. 2~, the lower section of the mandrel
13 assembly is provided with a piston 36 which carries a seal 37
14 that engages the wall 38 of an annular recess 39 formed in the
cylinder section 29 of the housing 25. The mandrel assembly 34
16 also carries seals 40 and 44 that engage housing wall surfaces 42
17 and 43 above and below the recess 39, with the surfaces 42 and 43
18 being formed on the same diameter. Initially, the regions above
19 and below the piston 36 contain air at atmospheric pressure. The
lower region is in communication with a pressure channel 45 that
21 terminates in an outwardly directed threaded port 46 tFig. 3)
22 which normally is closed by a rupture disk assembly 47 shown in
23 Fig. 4. As will be recognized by those skilled in the art, the
24 rupture disk 48 will remain intact until a predetermined pressure
is applied thereto which causes the central portion ~9 of the
26 disk to fail and thereby admit annulus fluids under pressure into
27 the region below the piston 36.
28 The tubular section 50 of the mandrel assembly 34 that
29 carries the seal 40 is provided with an outwardly extending
flange 51 which initially is located underneath a split lock ring
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1 52 to hold the same in its expanded condition. Upward movement
2 of the mandrel assembly 34 will move the flange 51 out from
3 underneath the split lock ring 52 and enable it to resile in-
4 wardly to its retracted condition where it is positioned between
the downwardly facing shoulder 53 on the lower end of the flange
6 51 and an upwardly facing shoulder 54 that is formed on the upper
7 end of the cylinder section 29 of the housing 25. In the re-
8 tracted position, the lock ring 52 prevents downward movement of
9 the mandrel assembly 34 with respect to the housing 25.
The upper end section 56 of the mandrel assembly 34, as
11 shown in Fig. 2A, is provided with three vertically spaced seal
12 rings 57, 58, 59 that engage the inner wall surface 60 of the
13 upper housing sub 27. A port 62 extends laterally through the
14 wall of the sub 27 and a companion pressure channel 63 extends
from a lateral opening 64 upwardly through the housing wall where
16 the channel may be communicated with the pressure operated piston
17 or the like in an associated pressure controlled well tool 21
18 (Fig. 1) such as a reversing valve. The upper and middle seal
19 rings 57, 58 normally are positioned respectively above and below
the port 64 as sho~n to blank off the same, whereas the middle
21 and lower seal rings 58, 59 normally are located respectively
22 above and below the port 62 to blank it off to fluid flow. When
23 the mandrel assembly 34 is shifted upward as~previously des-
24 cribed, the middle seal 58 moves above the port 64 to a position
where the annular clearance space 65 communicates the two ports
26 62 and 64 with one another to enable well annulus pressure, and
27 changes in such pressure, to be applied to the associated well
28 tool 21 for the purpose of operating or controlling the same.
29 Upper and lower sleeves 66, 67 that are fixedly mounted
within the housing section 28 carry eccentric pins 68 that are
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1 laterally offset from the center line of the housing as shown in
2 Fig. 5. The mandrel assembly 34 in its central region includes
3 arms 70 and 70' to either side which have circular outer walls 71
4 ana flat inner walls 72. Upper and lower ball valve elements 73
and 74 are rotatably mounted on the arms 70 and 70' by diame-
6 trically opposed trunion pins 75 that fit in holes 76 formed in
7 the flat side walls of the ball elements 73, 74 and extend into
8 apertures 77 formed in the arms 70 and 70'. Each ball valve
9 element has a bore 78 that when aligned with the housing axis
presents an unobstructed vertical passage through the tool.
11 Upper and lower valve seat rings 79, 80 carry seals 81 that
12 slidably engage the spherical outer peripheries 82 o~ the res~
13 pective ball valve elements to close off the central flow passage
14 to fluid flow when the valves are rotated through an angle of 90
to the orientation shown in Figs. 2A and 2B.
16 Each of the ball valve elements 73, 74 has radially ex-
17 tending cam slots 86 formed in the opposite side walls thereof
18 which are engaged by the eccentric pins 68, 68'. Thus arranged,
1~ upward shiting of the ball valve elements with the mandrel
assembly 34 causes the elements to be rotated simultaneously to
21 thelr closed positions with respect to the seat rings 79 and 80,
22 and downward shifting causes the elements to simultaneously
23 rotate open. When closed, the region 35 between the ball valve
24 elements 73, 74 and the annulax open areas outside the mandrel
from the seal 59 down to the seal 40 provide a chamber for trap-
26 ping a ~lowing sample of formation fluids. The annular space 88
27 located between the mandrel assembly 34 and the inner wall of the
28 housing section 28 above the upper ball valve element 73 is
29 communicated by a vertical port 89 to a typical drain plug as-
3~ sembly 90 shown in F'ig. 6 that enables the samp:e of formation
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1 fluids trapped in the chamber to be removed when the tool has
2 been removed from the well. An identical drain plug assembly may
3 be located in the wall of the cylinder section 29 at the lower
4 ~nd of a vertical port 89'.
6 OPERATION
In operation, the sampler-safety valve apparatus 20 as-
8 sembled as shown in the drawings is incorporated into the string
9 of drill stem testing tools above the main test valve 13, and the
string is run into the well on the pipe string 11. During run-
11 ning of the tools and operation of the test valve 13, the ball
12 valve elements 73 and 74 are in their open positions shown in
13 Figs. 2A and 2B. The enclosed regions above and below the piston
14 36 initially contain an atmospheric pressure, so that the mandrel
assembly 34 is completely balanced with respect to pressure.
16 The rupture disk 48 is selected to have a burst pressure
17 rating such that it will remain intact during all of the annulus
18 pressure changes that are employed to operate the main test valve
19 13. However, when it is desired to terminate the test and obtain
a sample, a pressure increase in excess of that employed to
21 activate the test valve 13 is applied at the surface to the well
22 annulus 22. Such pressure increase ruptures the central region
23 49 of the disk 48 to ~dmit annulus fluid via the port 45 into the
24 reg.ion below the piston 36 on the mandrel assembly 34. Upward
force on the piston 36 due to such pressure will shift the ~an-
26 drel assembly 34 upwardly within the housing 25, causing both of
27 the valve elements 73, 74 to be rotated simultaneously to their
28 closed positions to trap a sample of formation fluids in the
29 chamber 35. The lock ring 52 flexes inwardly underneath the
shoulder 53 on the mandrel to lock the sampler closed. The port
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1 62 in the upper section 27 of the housing 25 is communicated with
2 the vertical port 63 via the clearance space 64 to enable opera-
3 tion of associated equipment in response to subsequent changes in
4 the well annulus pressuxe.
When the tool string has been removed from the well, the
6 sample trapped in the chamber 35 and in the annular areas 88
7 outside the mandrel assembly can be removed by hooking up a drain
8 line to the threaded port 91 and then opening the plug valve 92.
9 The apparatus of the present invention also functions as a
safety valve because the throughbore of the tool string can be
11 closed at any time in response to the specific pressure signal
12 required to actuate the sampler valves. It also will be re-
13 cognized that'the ball valves 73 and 74 have the capability of
1~ cutting a wireline that may be extending therethrough where the
valves must be closed quickly in the event of an emergency, or
16 where a wireline tool has become hung in the tool string below
17 the sampler.
18 It will now be apparent that a new and improved full bore
19 sampler-safety valve apparatus has been disclosed. Since certain
changes or modifications may be made by those skilled in the art
21 without departing from the inventive concepts involved, it is the
22 aim of the appended claims to cover all such changes and modi-
23 fications falling within the true spirit and scope of the present
2~ invention.
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