U.S. patent number 3,876,003 [Application Number 05/410,944] was granted by the patent office on 1975-04-08 for drill stem testing methods and apparatus utilizing inflatable packer elements.
This patent grant is currently assigned to Schlumberger Technology Corporation. Invention is credited to James W. Kisling, III.
United States Patent |
3,876,003 |
Kisling, III |
April 8, 1975 |
Drill stem testing methods and apparatus utilizing inflatable
packer elements
Abstract
Methods and apparatus for isolating a well bore interval
utilizing spaced inflatable packer elements and a pump suspended in
the well on a pipe string. The pump includes an inner member
connected to the packer elements and an outer member connected to
the pipe string, said members defining a working volume that is
contracted during upward movement of said outer member for
supplying fluids under pressure to said packing element to effect
inflation thereof, and enlarged and filled with well fluids during
downward movement. Since the power stroke of the pump is in the
upward direction, a weight indicator can be monitored at the
surface and provides positive indication of downhole equipment
performance, including development of inflation pressures and the
opening of relief valves when preselected inflation pressures have
been generated.
Inventors: |
Kisling, III; James W.
(Houston, TX) |
Assignee: |
Schlumberger Technology
Corporation (New York, NY)
|
Family
ID: |
23626904 |
Appl.
No.: |
05/410,944 |
Filed: |
October 29, 1973 |
Current U.S.
Class: |
166/387; 166/191;
166/187 |
Current CPC
Class: |
E21B
34/125 (20130101); E21B 33/1246 (20130101); E21B
49/088 (20130101) |
Current International
Class: |
E21B
49/00 (20060101); E21B 34/12 (20060101); E21B
33/12 (20060101); E21B 49/08 (20060101); E21B
34/00 (20060101); E21B 33/124 (20060101); E21b
033/134 (); E21b 049/00 () |
Field of
Search: |
;166/250,113,138,186,187,216,240,191,315 ;73/151 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Novosad; Stephen J.
Attorney, Agent or Firm: Moseley; David L. Sherman; William
R. Moore; Stewart F.
Claims
I claim:
1. A method for isolating an interval of earth formations with a
packer means having at least one inflatable packing element that
can be expanded in response to operation of a pump means having
relatively movable inner and outer members defining a working
volume, one of said members being connected to said packer means
and the other of said members being connected to a pipe string
extending upwardly to the surface, comprising the steps of:
releasably locking said members against relative movement to
temporarily disable said pump means; lowering said packer means and
pump means into a fluid filled well bore on the pipe string; at
setting depth, anchoring said packer means and said one member
against downward movement in the well bore and releasing said
members for movement relative to each other to enable operation of
said pump means; moving said pipe string upwardly and downwardly to
effect corresponding movement of said other member relative to said
one member; during upward movement of said pipe string and said
other member discharging fluid under pressure into the interior of
said packing element to inflate and expand it outwardly; and during
downward movement of said pipe string and said other member drawing
well fluids into said pump means for discharge during the next
subsequent upward movement.
2. The method of claim 1 including the further step of venting
fluid from the pump means to the well annulus when the pressure
interiorly of said packing element reaches a predetermined maximum
value.
3. The method of claim 2 including the further steps of providing
an indication at the surface of the increase in the amount of force
required to move said pipe string upwardly as the pressure
interiorly of said packer element increase; and discontinuing
upward and downward movement of the pipe string when the amount of
force required to cause such upward movement ceases to increase and
thus indicates that said fluids are being vented to the well
annulus.
4. The method of claim 3 including the further steps of performing
a drill stem test by flowing formation fluids from below said
packing element into the pipe string for a first period of time;
shutting in the formation interval for a second period of time; and
instrumentally recording the pressure of the fluids in said
isolated interval during said periods of time.
5. The method of claim 4 including the further steps of deflating
said packer means to enable said packing element to retract to
substantially its normal transverse dimension so that said packer
means and pump means can be moved longitudinally through the well
bore.
6. A method for isolating an interval of earth formations off the
bottom of a well bore, comprising the steps of: lowering vertically
spaced, upper and lower inflatable packer elements, and a pump
means into the well bore on a pipe string, said pump means having a
working volume provided between an inner member connected to said
upper packer means and an outer member connected to said pipe
string; anchoring said packer elements and said inner member
against downward movement in the borehole; moving said pipe string
upwardly and downward to effect corresponding movement of said
outer member relative to said inner member; during each upward
movement pumping fluid under pressure into the respective interiors
of said upper and lower packing elements to expand them outwardly;
and during each downward movement resupplying said pump means with
fluids to be discharged to said packer elements during the next
subsequent upward movement of said pipe string.
7. The method of claim 6 including the further step of monitoring
the inflation pressure within the packing elements at the surface,
and discontinuing upward movements of the pipe string when an
indication is given that the inflation pressure has reached a
predetermined maximum value.
8. The method of claim 7 including the further step of exhausting
fluids from the pump means to the well bore when said maximum value
of inflation pressure is reached.
9. The method of claim 8 wherein the monitoring step is carried out
through observation of the amount of force required to lift the
pipe string during successive upward movements thereof, said
discontinuing step being carried out as soon as an appreceable
increase in the amount of force required to lift the pipe string
during successive upward movements is no longer observed.
10. The method of claim 9 including a further step of equalizing
the pressure of fluids in the well bore above the upper packing
element with the pressure of fluids in the well bore below the
lower packing element.
11. Apparatus for use in isolating an interval of earth formations
traversed by a well bore, comprising: packer means having at least
one inflatable element adapted to be expanded into sealing contact
with a surrounding well bore wall; pump means for inflating said
element, said pump means including relatively movable inner and
outer members defining a working volume, one of said members being
connected to said packer means and the other of said members being
connected to a pipe string extending upwardly to the surface;
releasable clutch means for preventing relative movement of said
members as said apparatus is being moved longitudinally in a well
bore; means for anchoring said packer means and said one member
against downward movement in the well bore; first means for feeding
fluid under pressure from said working volume to the interior of
said packing element during upward movement of said other member
relative to said one member; and second means for drawing well
fluids into said working volume during downward movement of said
other member relative to said one member.
12. The apparatus of claim 11 wherein said first means includes an
inflation passage leading from said working volume to the interior
of said packing element, and valve means for enabling fluid to flow
via said passage in a direction to enable expansion of said packing
element during said upward movement and for preventing the flow of
fluids in the reverse direction.
13. The apparatus of claim 12 wherein said second means includes an
entry passage leading from the well annulus to said working volume,
and valve means for enabling fluids to enter said working volume
means via said entry passage during said downward movement and for
normally preventing fluid flow in the reverse direction.
14. The apparatus of claim 13 further including a normally closed
vent passage for exhausting fluid from said working volume to the
well annulus; and pressure responsive relief valve means for
enabling fluids to vent to the well annulus via said vent passage
during said upward movement of said other member only after a
predetermined maximum inflation pressure has been generated within
said packing element.
15. The apparatus of claim 14 further including a test passage
extending generally longitudinally through said packer means and
said pump means; and test valve means for selectively opening and
closing said test passage to enable performance of a drill stem
test.
Description
This invention relates to new and improved methods and apparatus
for conducting a drill stem test of an earth formation that is
traversed by a borehole. More particularly, the invention concerns
unique methods for performing a drill stem test through use of
spaced inflatable packer elements that function to isolate the test
interval, and a pump actuated by upward and downward movement of
the pipe string in a manner that enables positive surface
indications of the performance of downhole equipment.
A drill stem test may be characterized as a temporary completion of
a newly drilled well during which pressure measurements are made
that enable various highly critical formation characteristics, such
as permeability and initial reservoir pressure, to be determined.
In addition, a sample of the formation fluids is taken and brought
to the surface for analysis. The drill stem test is considered to
be an indispensable technique for use in arriving at an informed
decision on whether it will be commercially feasible to set casing
and complete production from the particular zone of interest.
In certain well bore conditions such as washed out or otherwise
enlarged are irregularly diametered bores, it is common practice to
use test equipment that incorporates inflatable packers to isolate
the interval undergoing test. The inflatable packer incorporates an
elastomeric sleeve that is expanded outwardly by internal fluid
pressure into sealing contact with the well bore wall, and by its
nature has the capability for sealing off in a fairly wide variety
of hole sizes and shapes. The pressure for inflating the packer is
developed by a downhole pump that is operated in response to
manipulative movements of the pipe string, either upward and
downward or rotational.
One of more widely used inflatable packer systems is shown, for
example, in U.S. Pat. No. 3,439,740, issued to G. E. Conover.
According to the disclosure, the pump is operated in response to
rotation of the pipe string which causes a transverse circular
camway to reciprocate a plurality of pistons. As each piston
reciprocates, well fluids are alternately drawn in from the well
bore and then supplied under pressure to the interior of the
pliable sleeve elements, causing them to expand into sealing
contact with the well bore wall. When a predetermined inflation
pressure has been generated, depending upon the number of turns or
revolutions of the pipe string, a relief valve opens to limit the
magnitude of the inflation pressure. However, it is very difficult
if not impossible to detect at the surface when the packing
elements are fully inflated, because there is no apparent change in
the amount of torque required to turn the pipe when the pressure
relief valves open. On the other hand it is not highly reliable to
be dependent upon the number of turns of the pipe as indicating
that a packer seat has in fact been attained, because the size of
the borehole and thus the expansion requirement of the packers may
not be known. Thus as a matter of practice, the operator will
usually resort to pulling on the pipe at the surface to try to
determine from the frictional restraint afforded by the packers
whether or not they appear to be firmly set. Such a technique
obviously involves a high degres of trial and error and
uncertainty, all of which are highly undesirable.
One object of the present invention is to provide a new and
improved drill stem testing apparatus that is simple and reliable
in operation.
Another object of the present invention is to provide new and
improved methods of utilizing inflatable packer drill stem testing
apparatus in such a manner that positive surface indications are
provided of the successful operation of the downhole equipment.
These and other objects are attained in accordance with the
concepts of the present invention through practice of methods
comprising the steps of lowering an inflatable packer having one or
more expansible elements together with a pump into the borehole and
positioning the elements to isolate a formation interval of
interest. The pump includes relatively movable inner and outer
members, one of which, for example the inner one, is connected to
the packer assembly and the other of which, for example the outer
member, is attached to the pipe string upon which the equipment is
lowered. The packer assembly and the inner member next are anchored
against downward movement in the borehole, and then the pipe string
is moved upwardly and downwardly to effect corresponding reductions
and expansions of the working volume of the pump which is defined
in an annular space between the two members. During each upward
movement, fluids under pressure are fed into the respective
interiors of the inflatable elements, and during each downward
movement the pump is recharged with well fluids to be supplied
during the next subsequent upward movement. When a predetermined
maximum inflation pressure has been developed within the elements,
pressurized fluid from the working volume of the pump is
automatically discharged to the well annulus. Inasmuch as the
pumping power stroke is in the upward direction, it is possible for
the inflation pressure to be monitored at the surface by observing
the rig weight indicator during each upward movement of the pipe
string. It will be recognized that the weight values shown by the
indicator will increase in direct relation to the increases in
pressures developed by the pump during each upward movement, so
that when such increases no longer appear, but rather the weight
value remains constant during several upward movements, positive
indication is given that the relief valve is opening and that a
predetermined inflation pressure necessary to obtain proper seating
of the packer elements has in fact been developed. Operation of the
pump thus can be discontinued, and the formation interval is
effectively isolated to enable a drill stem test to be conducted.
Thus the present invention provides a technique for isolating a
well interval with inflatable packers that is much more reliable
and positive than has been the case with prior art practices,
particularly those involved with rotationally operable devices.
The present invention has many other objects, features and
advantages that will become more clearly apparent in connection
with the following detailed description of a preferred embodiment,
taken in conjunction with the appended drawings in which:
FIGS. 1A and 1B are schematic views of the string of drill stem
testing tools, utilizing inflatable packers suspended in a well
bore;
FIGS. 2A and 2B are detailed cross-sectional views with portions in
side elevation, of the formation test valve assembly, FIG. 2B
forming a lower continuation of FIG. 2A;
FIG. 3 is a sectional view of the pressure bleed-off valve that
operates during expansion of the packing elements;
FIGS. 4A and 4B are sectional views similar to FIG. 2 of the
screened fluid intake for the packer inflating pump;
FIGS. 5A and 5B are longitudinal sectional views, with portions in
side elevation, of the pump assembly that is operated by vertical
pipe motion to inflate the packing elements;
FIGS. 6A and 6B are cross-section views of the pressure equalizing
and packer deflating valve sub; and
FIGS. 7A-7C are cross-section views of the inflatable packer
assembly with upper and lower packer elements coupled by a spacer
sub to enable a formation interval to be straddled and sealed off
at each end;
FIG. 8 is a longitudinal sectional view of a pressure equalizing
sub that can be connected to the lower end of the packing assembly;
and
FIGS. 9A-9C are fragmentary sectional views showing the various
operating positions of the valve assemblies that control the intake
and supply of pressurized fluid to and from the pump assembly.
Referring intially to FIGS. 1A and 1B for a schematic illustration
of the entire string of drill stem testing tools disposed in the
borehole in position for conducting a test of an interval of the
well, the running-in string 10 of drill pipe, or tubing is provided
with a reverse circulating valve 11 of any typical design, for
example a valve of the type shown in U.S. Pat. No. 2,863,511,
assigned to the assignee of this invention. A suitable length of
drill pipe 12 is connected between the reverse circulating valve 11
and a multi-flow evaluator or test valve assembly 13 that functions
to alternately flow and shut-in the formation interval to be
tested. A preferred form of test valve assembly 13 is shown in my
U.S. Pat. No. 3,308,887, also assigned to the assignee of this
invention. The lower end of the test valve 13 is connected to a
pressure relief valve 14 that is, in turn, connected to a recorder
carrier 15 that houses a pressure recorder of the type shown in the
assignee's U.S. Pat. No. 2,816,440. Of course the recorder
functions to make a permanent record of fluid pressure versus
lapsed time during the test in a typical manner. The recorder
carrier 15 is connected to the upper end of a screen sub 16 that
serves to take in and to exhaust well fluids during operation of
the packer inflation pump assembly 17 to which the lower end of the
screen sub is connected. The pump assembly 17, which together with
the various other component parts of the tool string, will be
described in considerably greater detail below, includes inner and
outer telescoping members and a system of check valves arranged so
that well fluids are displaced under pressure during upward
movement of the outer member with respect to the inner member, and
are drawn in via the screen sub 16 during downward movement. Thus a
series of vertical upward and downward movements of the running-in
string 10 is effective to operate the pump assembly 17 and to
supply pressurized fluids for inflating the packers to be described
below.
The lower end of the pump assembly 16 is coupled to an equalizing
and packer deflating valve 18 that can be operated upon completion
of the test to both equalize the pressures in the well interval
being tested with the hydrostatic head of the well fluids in the
annulus above the tools and to enable deflating the packer elements
to their normally relaxed condition. Of course an equalizing valve
is necessary to enable the packers to be released so that the tool
string can be withdrawn from the well. The valve 18 is connected to
the upper end of a straddle-type inflatable packer system shown
generally at 19, the system including upper and lower inflatable
packers 20 and 20' connected together by an elongated spacer sub
22. The inflatable packers 20 and 20' each include an elastomeric
sleeve that is normally retracted but which can be expanded
outwardly by internal fluid pressure into sealing contact with the
surrounding well bore wall. The length of the spacer sub 22 is
selected such that during a test the upper packer 20 is above the
upper end of the formation interval of interest, and the lower
packer 20' is below the interval. Of course when the packer
elements are expanded as shown in FIG. 1A, the well interval
between the elements is isolated or sealed off from the rest of the
well bore so that fluid recovery from the interval can be conducted
through the tools described above and into the drill pipe 12.
The lower end of the packer system 19 can be connected to a slip
joint and equalizing valve 23 which is, in turn, connected to an
anchor 24 that may be of the hook-wall variety, an example of which
is shown in U.S. Pat. No. 3,015,362, again assigned to the assignee
of this invention. The anchor 24 typically comprises an expander
cone 25 that is arranged to shift a set of normally retracted slips
26 outwardly into gripping contact with the well bore wall. During
running, the slips are conditioned in the retracted position by a
jay-slot and pin arrangement (not shown) which can be manipulated
to a released condition due to the presence of drag springs 27 that
frictionally engage the well bore wall. Through use of such an
anchor it is possible to test well formations located at most any
elevation in the borehole. If desired, another recorder carrier 28
can be positioned between the anchor 24 and the lower equalizing
valve 23 and arranged to measure directly the formation fluid
pressure in the isolated interval to enable a determination by
comparison with the pressure readings of the recorder in the upper
carrier 15 whether the test passages and ports have become blocked
by debris or the like during the test. Although not shown in FIG.
1, it will be appreciated that other tools such as a jar and a
safety joint may be incorporated in the string, for example between
the test valve assembly 13 and the pump assembly 17, in accordance
with typical practice.
As shown rather schematically in FIG. 1A, the pipe string 10
extends upwardly to the surface where it is suspended for handling
within a derrick D by typical structure such as a swivel S,
traveling block B and cable C extending between the traveling block
and the crown block S' at the top of the derrick. The dead line of
the cable has a transducer such as a load cell thereon to sense the
weight of the drill string and the tools in the borehole. The
output of the transducer is coupled to a weight indicator W that
provides the rig operator with a visual indication of the precise
amount of weight being supported by the cable and the derrick at
all times. Of course the line end of the cable extends to a
drawworks that is used in typical manner to raise and lower the
pipe as desired.
Turning now to a more detailed description of the various component
parts of the string of drill stem testing tools, reference
initially will be made to the inflatable straddle packer system 19
shown in FIGS. 7A-7C. The system includes a body member or mandrel
30 having its upper end fixed to an upper sub 31 and its lower end
fixed to a lower sub 32. An inflatable packer element 20 surrounds
the mandrel 30 and may be constituted by an elongated sleeve of
elastomeric material such as neoprene that is internally reinforced
by plies of woven metal braid or the like (not shown). The upper
end of the element 20 is fixed to a collar 33 that is threaded to
the upper sub 31, and may be retained with respect to the collar by
means such as a frusto-conical ring that is forced against an inner
surface of the element 20 by a lock nut or the like. Such structure
is well known to those skilled in the art and need not be further
elaborated here. One or more inflation ports or passages 34 extend
vertically through the upper sub 31 and communicate with the
annular space 35 between the inner wall surface of the sleeve 20
and the outer periphery of the mandrel 30. The lower end of the
packer element 20 is also sealed and fixed with respect to an end
cap 36 that is sealingly slidable along the mandrel 30, the lower
portion of the mandrel being constituted by the combination with a
passage sleeve 37 fitted around the mandrel 30 and laterally spaced
therefrom to provide a continuation 38 of the passage space for
inflation fluids. The upper sub 31 has a hollow seal sleeve 39
threadedly fixed therein and adapted to receive the lower end of an
elongated flow tube 40 that extends upwardly within the equalizing
and packer deflating valve assembly 18. The seal sleeve 39 carries
seal rings 41 and is located in spaced relation above a transverse
solid section 42 of the sub 31 which has, in addition to the
inflation ports 34, a plurality of test ports 43 extending
vertically therethrough. The ports 43 communicate with an annular
fluid passage space 44 that is within the packer mandrel 30 but
outside of a hollow flow tube 45 extending concentrically within
the bore of the mandrel. The upper end of the flow tube 45 is
threaded into the transverse section 42, and the bore 46 of the
flow tube is opened to the well annulus outside the upper sub 31 by
one or more laterally directed equalizing ports 47 that are
angularly spaced in a transverse plane with respect to both the
inflation ports 34 and the test ports 43.
The lower sub 32 as shown in FIG. 7B is threaded to the lower end
of the packer mandrel 30 and has vertically extending inflation
passages 50 whose upper ends are placed in communication with the
annular sleeve passage 38 by a collar 51 that is threaded to the
sub 32 and sealed with respect to the sleeve 37 by an O-ring 52.
The flow tube 45 has its lower end received within a seal sleeve 53
that is threadedly fixed within the bore of the lower sub 32 and
connected to another flow tube 54 that extends downwardly
concentrically within the spacer sub 22. The annular fluid passage
space 44 between the tube 45 and the mandrel 30 is communicated
with the well annulus by a plurality of laterally directed ports 55
to enable formation fluids recovered during a test to enter the
passage space 44 and pass upwardly through the tools. On the other
hand the annular space 56 between the lower flow tube 54 and the
spacer sub 22 continues a passage for inflation fluids that extend
past an internal seal sleeve 56 at 57 and eventually communicates
with vertically disposed inflation ports 58 in the upper sub 59 of
the lower packer element assembly 20'. The lower assembly is
substantially similar to the upper assembly 20 in its arrangement
of an inflatable elastomeric packer element 61 (FIG. 7C) that
surrounds a mandrel 62 with the upper end of the element fixed to a
collar 63 and the lower end fixed to a movable end cap 64 that is
sealingly slidable on an outer sleeve 65 that surrounds the lower
end portion of the mandrel. The lower end of the mandrel 62 is
fixed to a lower sub 66, and a collar 67 carrying an O-ring seal 68
provides an internal recess 69 that communicates the inside 70 of
the packer element 61 with one or more ports 71 that extend
vertically throughout the sub 66. Thus it will be recognized that
the respective interiors of the inflatable elements 20 and 20' are
in continuous communication with one another so that fluid pressure
applied thereto via the various intercommunicating passages 34, 35,
38, 50, 56, 58 and 70 will cause the elements to be expanded from
their normally relaxed or retracted positions as shown in FIGS.
7A-7C to a substantially greater diameter where their outer
peripheries come into sealing contact with an adjacent well bore
wall. When expanded, the elements seal off the ends of an interval
of the well bore to enable a formation test to be conducted.
Referring again to FIG. 7B, the intermediate flow tube 54 extends
downwardly throughout the spacer sub 22, and its lower end extends
through the seal sleeve 56 in a fluid-tight manner. Of course the
bore 74 of the flow tube 56 communicates with the bore 46 of the
upper flow tube 45 and thus with the well bore above the upper
packing element 20 via the lateral ports 47. The lower end of the
bore 74 also communicates with a series of ports 75 extending
through an otherwise solid transverse section 76 of the upper sub
59, the ports 75 leading to an elongated annular flow path 77
located internally of the mandrel 62. Yet another, lower, flow tube
78 has its upper end fixed to the transverse section 76 and extends
downwardly throughout the mandrel 62, with its outer wall defining
the inner periphery of the annular flow path 77. The lower end of
the flow path 77 is communicated with the well bore as shown in
FIG. 7C by a plurality of lateral ports 79 through the wall of the
lower sub 66, the lower end of the space between the tube 78 and
the sub 66 being blocked by a seal sleeve 80 carrying appropriate
O-rings. Accordingly, it will be recognized that the lateral ports
79 and 47 and the internal passages 46, 74, 75 and 77 provide for
pressure equalization between the pressure of the fluids in the
well bore above the upper packing assembly 20 and the pressure of
the fluids in the well bore below the lower packing assembly 20' at
all times.
The lower sub 66 of the lower packer assembly 20' is attached by a
collar 85 to an inner tubular member 86 that is slidably received
within an outer tubular member 87 as shown in FIG. 8, the two
members being corotatively coupled by splines 88 and 89 and forming
a slip joint and equalizing valve assembly 23. An inner sleeve 90
is concentrically disposed within the member 86 and is laterally
spaced with respect thereto to provide a flow path 91 that
communicates with the vertical ports 71 in the lower sub 66 of the
packer assembly 20'. The lower end of the sleeve 90 has an
outwardly directed flange that carries O-rings in sealing contact
with the lower end portion of the member 86, and the flow path 91
is conducted through the wall of the member 86 by one or more
ports. A ported ring 92 having upper and lower, inner and outer
seals 93 and 94 is fixed between opposed shoulders of the members
86 and slidably engages the inner wall surface 95 of the outer
member 87. It will be apparent that the ring 92 forms the remote
lower end of the various intercommunicated inflation passages
leading to and through to the packing elements 20 and 20', and that
the lower end of such passages remain closed as long as the member
86 and 87 occupy the mutually telescoped relative position shown in
FIG. 8. On the other hand if the members are caused to extend, the
ring 92 will be moved adjacent to a plurality of side ports 97
through the wall of the outer member 87 so that the lower end of
the inflation passage is communicated with the well annulus to
enable fluids to exit from the interior space of the elements 20
and 20'.
As previously mentioned, the internal sleeve 90 has its upper end
threaded to the seal sleeve 80 that is fixed within the lower sub
66 of the lower packing assembly 20'. The bore 98 of the sleeve 90
is thus in fluid communication with the bore 99 of the lower flow
tube 78 whose upper end is threaded into the solid section 76 of
the upper sub 59 as shown in FIG. 7B. A counterbore in the section
76 is opened to the well annulus by lateral ports 100 so that a
pressure recorder housed in the carrier 28 attached to the collar
101 below the slip joint and equalizing valve 23 will "see" the
pressures of fluids in the well annulus between the upper and lower
inflatable packing element assemblies 20 and 20'. This pressure
recorder, shown schematically in FIG. 2B, provides a second or
"outside" recorder whose pressure record can be compared with the
data gathered by the upper or "inside" recorder at 14.
Turning now to FIGS. 5A and 5B, a preferred embodiment of a pump
assembly 17 that can be operated by manipulation of the pipe string
10 to cause expansion of the packer elements 20 and 20' is shown in
greater detail. The pump 17 includes a housing 105 that extends
downwardly in telescoping relation over a mandrel assembly 107 and
is arranged for reciprocating motion with respect thereto between
spaced longitudinal positions. The housing 105 is constituted by a
series of threadedly interconnected tubular members including an
upper sub 108, a cylinder section 109 and a splined section 110.
The mandrel assembly 107 also comprises a number of interconnected,
separate members including a flow tube 112, a valve section 113, a
cylinder section 114 and a jack thread section 115 which has a pipe
joint or collar 116 threaded on its lower end. Additionally, an
elongated tube 117 is fixed concentrically within the members 114
and 115 and has its outer surface laterally spaced with respect
thereto to provide an annular inflation fluid passage 118. The
through bores of tube 117 and the mandrel sections 113 and 112
provide a central opening 119 for the passage of formation fluids
through the pump assembly 17 from one end to the other. The upper
sub 108 has an internal thread 120 for connection with the screen
assembly 116 immediately thereabove, whereas the collar 116 has a
similar thread 121 to adapt it for connection to the packer deflate
and equalizing valve 18 located below the pump assembly 17.
Normally, that is when the tools are being lowered into the
borehole, the housing 105 is locked in a lower position with
respect to the mandrel assembly 107 by a clutch nut 123 (FIG. 5B)
that is threaded at 124 to the mandrel section 115 and has a
slidable spline connection 125 to the housing section 110. The
clutch nut 123 engages above an inwardly extending shoulder 126 at
the lower end of the housing section 110 to prevent upward
movement, and several stacked thrust washers or bearings 127 can be
located between the shoulder 126 and the upper face of the collar
116 to enable rotation with relative ease. Rotation of the housing
105 with respect to the mandrel assembly 107 will cause the clutch
nut 123 to feed upwardly until it comes into contact with a
shoulder 128 on the mandrel, in which position the housing 105 is
free to be moved upwardly and downwardly within limits along the
mandrel assembly 107 in response to vertical motion of the pipe
string 10 at the surface.
The lower end of housing cylinder section 109 is provided with a
sleee piston 129 that is sealed with respect to the mandrel
cylinder section 114 by seal rings 130. The annular cavity 131
located above the sleeve piston 129 provides the working volume of
the pump. The upper end of the cylinder space 131 is defined by a
check valve system indicated generally at 132 which includes a
fluid intake valve 133 and an exhaust valve 134. The intake valve
133 comprises an annular member that is pressed upwardly by a coil
spring 135 against a valve seat ring 136, whereas the exhaust valve
134 is constituted by a stepped diameter sleeve that is pressed
downwardly by the coil spring 135 in a lower position where it
spans one or more fluid exhaust ports 137 that lead to the annular
inflation passage 118 located between the hollow tube 117 and the
inner surface of the mandrel cylinder section 114. Inasmuch as the
valve sleeve 134 has a resultant transverse pressure area defined
by the difference between the seal areas of the rings 138 and 139,
it will be appreciated that a greater fluid pressure generated in
the cylinder space 131 during upward movement of the housing 105
relative to the mandrel assembly 107 will shift the valve sleeve
upwardly against the bias afforded by the coil spring 135 to a
position uncovering the exhaust ports 137, as shown in greater
detail in FIG. 9A, so that fluids under pressure can be supplied to
the passage 118. On the other hand, during downward relative
movement the spring 135 pushes the valve sleeve 134 closed, and a
reduction in cylinder pressure below hydrostatic fluid pressure
will cause the intake valve 133 to move away from the seat ring 136
as shown in FIG. 9B, thereby admitting well fluids into the
cylinder space 131 and allowing it to fill during such downward
relative movement. When the housing 105 reaches the bottom of its
stroke, the spring 135 will push the intake valve 133 upwardly to
closed position so that the pumping cycle can be repeated. As shown
in FIG. 5A, the intake valve 133 carries a seal ring 140 that seals
against the inner wall surface of the housing section 109, and is
slidably arranged around a thickened wall portion of the mandrel
section 113 which is longitudinally grooved at 141 to provide for
fluid entry past the valve. The valve seat ring 139 may be provided
with spaced apart, annular projections on its lower face that
straddle the grooves 141 to provide a fluid tight interfit in the
closed position of the valve, the inner projection resting on a
mandrel shoulder 147 and the outer projection abutting the top
surface of the valve element 133.
It should be noted at this point that the valve seat ring 136 is
vertically movable to some extent, but normally is held in its
lower position by a yieldable structure 143 that may comprise, for
example, a series of Bellville washers located below an adjustable
retaining nut 144 threaded on the mandrel section 113. The nut 144
and the washers 143 are located on a reduced diameter portion 145
of the mandrel section, the portion 145 having circumferentially
spaced, longitudinally extending grooves 146 that provide for the
passage of fluids internally of the nuts 144 and the washers 143.
Thus it will be recognized that when the pressure generated in the
cylinder space 131 reaches a certain predetermined maximum value,
the seat ring 136 can be forced upwardly together with the valve
element 133 to disengage the inner projection from the shoulder
surface 147 as shown in FIG. 9C to allow pressurized fluids in the
cylinder space 131 to vent out of via the grooves 146. This system
dictates a maximum value of inflation pressure that can be supplied
by the pump assembly 17 to the inflatable packer elements 20 and
20', which valve is sufficient to fully expand them against the
well bore wall while providing a protection against excessive
inflation pressures that might otherwise result in damage. The
magnitude of the pressure at which the seat ring 136 will move
upwardly is set at a preselected value by adjustment of the preload
in the washer springs 143 through appropriate vertical adjustment
of the retainer nut 144.
The upper sub 108 of the housing assembly 105 provides fluids
passages to the check valve system 132 and is, as previously
mentioned, connected to the lower end of the screen assembly 16. As
shown in FIG. 5A, a seal nipple 149 on the lower end of the screen
assembly is sized to fit over the upper end of the tube 112 and
carries seal rings 150 that engage the internal wall surface 151 of
the sub 108. A plurality of vertically extending ports 152 serve to
conduct fluids from the screen assembly 16 through the wall of the
sub 108 and into the region above the check valve assembly 132. The
lower portion of the sub 108 carries a seal sleeve 153 with a
through bore that receives the tube 112. Seal rings 154 and 155
prevent fluid leakage between the ports 152 and the bore of the
tube 112 during longitudinal relative movement. The seal rings 154
engage on a smaller diameter than do the seal rings 130 on the
piston 129, so that during upward movement of the housing 105
relative to the mandrel assembly 107, a greater volume of well
fluids will be brought into the pump assembly 17 than is required
to fill the working volume of the pump during the next or
subsequent downward movement. Thus, during each downward movement,
not only is fluid supplied to fill the chamber 131, but also a
certain amount of the fluids is forced back upwardly into the
screen assembly 16 via the ports 152 to provide a back-flushing
action to ensure that the screen assembly, to be described in
detail hereinbelow, cannot become clogged by debris or other
foreign matter in the well fluids.
The upper end of the lower flow tube 117 is provided with an
enlarged head 159 that carries seal rings 160 and is interfitted
between a shoulder 161 on the mandrel section 113 and the upper end
face of the mandrel section 114. The lowermost end of the tube 117
is received by a flow coupling 162 (FIG. 5B) having seals 163 to
prevent fluid leakage. The flow coupling 162 has an outwardly
directed flange 164 at its upper end that is longitudinally grooved
to provide for the flow of inflation fluids from the passage 118
into the annular area between the coupling and the body of the
packer deflate and equalizing valve 18 connected immediately below
the pump assembly 19.
The well fluids coming into the pump assembly 17 pass through the
screen sub assembly 16 shown in FIGS. 4A and 4B, wherein inner and
outer members 170 and 171 are rigidly fixed and laterally spaced to
provide an annular passage space 172 that is placed in
communication with the well bore by a plurality of ports 173. The
lower end of the passage space 172 is joined by a port 174 to a
vertically disposed bore 175 that extends downwardly within the
wall section of a connecting sub 176 to communicate the fluids to
the interior of pump assembly 17. The seal nipple 149 is threaded
to the lower end of the connecting sub 176 and sealingly interfits
with the inner wall 151 of the upper sub 108 of the pump assembly
17 as previously described. The outer member 171 is provided with
an external recess throughout a major portion of its length, and a
screen element 178, formed of flat, spiral-wound wire other
suitable material, is positioned in the recess 177. The element 178
acts as a filter to prevent rock chips or other debris in the well
fluids from coming into the pump assembly 17. A tool joint of
collar 179 couples the upper end of the screen assembly 16 to the
pressure recorder carrier 15 located immediately thereabove. The
throughbore 169 of the member 170 continues the passage for the
flow of formation fluids upwardly through the tools.
Turning now to the structural details of the pressure equalizing
and packer deflating valve assembly 18 shown in FIGS. 6A and 6B,
which assembly functions to enable the pressure of fluids in the
isolated formation interval to equalize with the hydrostatic head
of fluid immediately above the upper packer 20 upon completion of
the test, as well as enabling the packer elements 20 and 20' to be
deflated, so that the tools can be withdrawn from the well, the
assembly comprises a mandrel 180 having an upper section 181 and a
lower section 182, the upper section being provided with a collar
183 to adapt it for connection to the lower end of the pump
assembly 17. The mandrel 180 is movable relatively within an outer
member or housing 184 formed of threadedly interconnected sections
185, 186 and 187, the lower section or sub 187 being adapted by
threads 188 for connection to the upper end of the packer assembly
19. The adjacent mandrel and housing sections 181 and 185 have
interengaged splines 188 and 189 to prevent relative rotation and
to provide limits for longitudinal relative movement. A valve
sleeve 190 is fixed by threads 191 to the lower end portion 187 of
the housing 184 and extends upwardly therein, and an elongated flow
tube 192 whose upper end is connected to the flow coupling 162
extends downwardly into the valve sleeve 190. The central bore 193
of the flow tube 192 provides an upward passage for formation
fluids that are recovered during the test, whereas the outer
periphery of the tube is spaced inwardly of the inner wall surface
of the mandrel 180 to provide a continuing inflation passage 194
leading from the pump assembly 17 to the packer assembly 19. The
telescoping joint comprising the members 180 and 184 can be readily
closed by downward movement of the mandrel 180, however upward
movement to open position is delayed for a significant time
interval by a hydraulic system including a metering piston 195
disposed within a chamber 196 located interiorly of the housing
section 186. The piston 195 is sized to provide for a restricted
leakage of hydraulic fluid from above to below it during upward
movement, however the piston can move away from an annular seat
surface 197 during movement so that hydraulic fluid can pass freely
through external grooves 198 in the mandrel section 182 behind the
metering piston. The chamber 196 is closed at its upper end by a
seal ring 199 and at its lower end by a floating balance piston 200
whose lower face is subject to the pressure of fluids in the well
annulus via ports 201. The balance piston 200 functions to transmit
the pressure of the well fluids to the hydraulic fluid below the
metering piston 195 so that the pressure in this region of the
chamber is never less than the hydrostatic fluid pressure in the
well bore outside.
The lower end section 202 of the mandrel 180 is provided with
external bypass grooves 203 that are arranged to communicate the
inflation passage 194 with the well annulus via the ports 201 when
the mandrel 180 is moved to its fully extended or open position
with respect to the housing 184. Communication is by virtue of the
fact that the upper ends of the grooves 203 will extend past the
O-ring seals 204 to enable fluids to flow from the inflation
passage 194 to the well annulus. Moreover the flow tube 192 is
provided with similar grooves 205 that normally are positioned
below a seal ring 206 on the valve sleeve 190. The upward movement
that opens the inflation passage 194 to the well annulus also will
position the upper ends of the grooves 205 above the seal ring 206
so that the formation fluid passage 193 is communicated with the
well annulus. When this occurs, all pressures, that is to say the
inflation pressure within the packer elements 20 and 20' and the
pressure in the well bore interval between the packers 20 and 20'
are equalized with hydrostatic pressure to enable the packers to
deflate and return to their normal, relaxed positions whereby the
tools can be withdrawn from the well.
The details of the test valve assembly 13 that is utilized to flow
and shut-in the formation once it has been isolated by the packer
assembly 19 in response to actuation of the pump 17 are shown in
detail in my U.S. Pat. No. 3,308,887, to which reference is made
herein. For purposes of completeness of this disclosure however,
the tester as shown in FIGS. 2A and 2B includes a mandrel 210 that
is connected to the pipe string 12 by a coupling 211. The mandrel
210 is telescopically disposed within a housing 212 whose lower end
is threadedly connected to the upper end of the pressure relief
valve assembly 14. The mandrel 210 is movable between a upper or
extended position and a lower or contracted position within the
housing 212 for the purpose of actuating a test valve to open and
close a flow path through the tools. The valve assembly as shown in
FIG. 2B comprises spaced upper and lower valve heads 213 and 213'
that can simultaneously engage valve seats 214 and 214' in order to
block fluid flow from within the housing below the lower valve head
into the bore 216 above a transverse barrier 217 in the mandrel
210, and which are disengaged from the valve seats by downward
movement in order to enable fluids to flow past the barrier via
ports 218, an annular elongated sample chamber 219, and ports 220
and 221. Seals 222 and 222' prevent fluid leakage in the closed
position. It should be noted that in the closed position, a sample
of the fluids flowing upwardly through the tester will be trapped
within the sample chamber 219 for recovery to the surface with the
tools for later inspection and analysis.
In addition to the valve and sampler section described immediately
above, the tester assembly 13 includes an index section 225 and a
hydraulic delay section 226. The index section 225 comprises a
sleeve 227 that is mounted for rotation relative to both the
housing 212 and the mandrel 210 and which carries an index pin 228
that works in a channel system 229 formed in the outer periphery of
the mandrel 210. The coaction of the index pin 228 with the channel
system 229 as the mandrel 210 is moved vertically within the
housing 212 causes the sleeve 227 to swivel between various angular
dispositions in order to position one or more internal spline
grooves 230 therein in such a manner that corresponding lugs 231 on
the mandrel either can or can not pass therethrough. Thus the index
system 225 functions basically to provide stops to downward
movement of the mandrel 210 in certain positions thereof as will be
further discussed hereinbelow. The delay section 226 (FIG. 2B)
includes a metering piston 233 that is mounted on the mandrel 210
and is slidable within a stepped diameter cylinder 234 in the
housing 212. The piston 233 is sized transversely in such a manner
that hydraulic fluid in the cylinder 234 can leak or meter past the
sleeve at a controlled rate during downward movement of the mandrel
210 until the sleeve enters the enlarged diameter portion 235 of
the cylinder, whereupon the mandrel 210 can move quickly downwardly
to its fully contracted position. The piston 233 is biased by a
spring 236 upwardly against a seat 237 provided by a shoulder 238
on the mandrel 210 so that hydraulic fluid can pass only around the
periphery of the sleeve during downward movement, however the
sleeve can move away from the seat during upward movement. When
disengaged from the seat, hydraulic fluid can bypass through
recesses 239 internally of the sleeve so that the mandrel 210 can
be moved rapidly upwardly to its fully extended position. The ends
of the chamber 234 are sealed off by elements 240 and 241 to
provide a closed system.
As previously mentioned, an overpressure relief valve assembly 14
is connected to the lower end of the tester housing 212 as shown in
FIG. 3, and includes a ported sub 245 having a stepped diameter
internal bore 246. The upper end of the sub 245 is connected by a
coupling to the lower threaded end of the housing 212, and the
lower end of the sub is threaded at 248 for connection to the upper
end of the pressure recorder carrier 15. A valve sleeve 249 is
longitudinally movable within the sub 245 between an upper position
where the side ports 250 provide communication between the well
annulus and the bore 251 of the sub, and a lower position as shown
where seals 252 and 253 are engaged to prevent fluid flow through
the ports. The valve sleeve 249 is sized and arranged to be pushed
downwardly to the lower position by a lower end extension 254 (FIG.
2B) of the tester mandrel 210 when the said mandrel is disposed in
its lowermost position relative to the housing 212, otherwise the
valve sleeve is responsive to force due to pressure differences
acting across the transverse cross-sectional area bounded by the
seal rings 252 and 253. Thus when the valve sleeve 249 is in the
lower closed position and the hydrostatic head of the well fluids
outside the ports 250 exceeds the pressure of fluids in the bore
251 of the sub 245, a downward force is developed to keep the valve
closed. On the other hand if there is a greater pressure of fluids
within the bore 251, upward force is developed tending to shift the
valve sleeve 249 upwardly to open position.
The valve assembly 14 operates to relieve excess pressures that may
be developed in the annular well bore area between the packer
elements 20 and 20' as they are inflated. It will be recognized
that once the inflatable elements effect a seal with the well bore
wall, and since the test valve 13 is not yet open, continued
enlargement of the elements by further pumping action will tend to
compress the entrapped well fluids therebetween and maay raise the
fluid pressure in the isolated interval to an excessive value.
However, since such pressure acts upwardly on the valve sleeve 243,
being communicated to the bore 251 by via the test ports 44 and the
various passages 45, 43, 193 and 169, the valve sleeve is forced
upwardly to vent fluid to the well annulus above the packer
assembly 19 and thereby relieve such excessive pressure. Of course
the valve sleeve 246 is forced downwardly to closed position by the
end extension 254 of the tester mandrel 210 as the test valve is
opened, and will be held in closed position throughout subsequent
testing operations by the greater hydrostatic pressure in the well
annulus acting through the ports 250 on the transverse pressure
area of the valve element.
OPERATION
In operation, the various components of the tool string are in the
end-to-end sequence as shown in FIGS. 1A and 1B of the drawings and
connected to the drill string 10 preparatory to lowering into the
well. The housing 105 of the pump assembly 17 is disposed in its
lower position with respect to the mandrel assembly 107, with the
clutch nut 123 also in its lower position where its function is to
releasably lock the housing and mandrel in a mutually telescoped
relationship. This disables the pump assembly 17 until such time as
the clutch is released to enable relative longitudinal movement of
the housing 105. Of course the inflatable packing elements 20 and
20' are both retracted, and the test valve assembly 13 is closed
inasmuch as the mandrel 210 is in an upper or extended position
relative to the housing 212, thereby disposing the valve heads 213
and 213' above the flow ports 220 and 218 to prohibit fluid flow.
As the equipment is lowered into the borehole to setting depth, the
drag springs 27 of the anchor assembly 24 frictionally engage the
walls of the bore to prevent rotation as well as to provide a
degree of restraint to vertical motion of the equipment. The pipe
string 10 is either empty of fluids or may be provided with a
column of water to act as a cushion as will be apparent to those
skilled in the art. In any event, the pipe string 10 provides a low
pressure region which can be communicated with an isolated section
of the borehole to induce fluids to flow from the formation into
the pipe string if they are capable of so doing.
When the packing assembly 19 is located opposite the formation
interval to be tested, the interval is isolated by inflating the
packing elements 20 and 20' into sealing contact with the
surrounding well bore wall in the following manner. The pipe string
10 is appropriately manipulated to unjay the slip cage with respect
to the body member of the anchor 24, and the equipment is lowered.
The slips 26 are held against downward movement by the drag springs
27, so that the expander 25 shifts the slips outwardly into
gripping contact with the wall of the borehole to prevent downward
movement. Next the pipe string 10 is rotated to the right to feed
the clutch nut 123 upwardly along the pump mandrel section 115 to
the upper position where the housing 105 is free to be reciprocated
with respect to the mandrel assembly 107. As the housing 105 is
elevated, it will be recognized that the weight of all of the
equipment therebelow will resist upward movement of the mandrel
assembly 107, so that pressure is generated within the chamber 131
above the piston 129. Such pressure will cause the check valve
sleeve 134 to shift upwardly and uncover the ports 137, so that
fluids under pressure are supplied via the inflation passage 118,
194 and 34 into the respective interiors of the packing elements 20
and 20'. The pressure causes the elements to inflate and bulge
outwardly. When the pump housing 105 reaches the top of its stroke,
thus having displaced its working volume of fluid into the
inflation passage 118, the pipe string 10 is lowered to recharge
the chamber 131 with well fluids. Of course the packer assembly 19
and the mandrel 10 of the pump assembly remain anchored against
downward movement by the slips 26. As the housing 105 moves
downwardly a reduction of pressure in the chamber 131 as it
enlarges in volume during such downward movement enables the spring
135 to push the valve sleeve 134 downwardly to close off the
passages leading to the packing elements 20 and 20'. As the
pressure is further reduced by an increase in the working volume
131, the hydrostatic head of the well fluids present above the
check valve assembly 132 forces the inlet valve 133 downwardly and
away from the seat ring 136, thereby enabling the chamber to fill
with well fluids as the housing 105 moves downwardly to the bottom
of its stroke. When the chamber 131 is fully expanded, the absence
of a pressure differential enables the spring 135 to push the inlet
valve 133 closed. A second upward movement of the housing 105 will
cause an additional volume of fluid under pressure to be displaced
through the various inflation passages and into the packing
elements 20 and 20' to increase their transverse dimension. In
typical practice, depending upon hole size in relation to the
relaxed diameter of the packer elements 20 and 20', a series of
seven to ten cycles of the pump 17 will be sufficient to cause the
respective outer peripheries of the element to engage the well bore
wall as shown in FIG. 2B. Continued actuation of the pump 17 in
response to upward and downard pipe motion will continually
increase the inflation pressure until the desired pressure is
reached. Immediately after the elements actually engage the well
wall, the assembly becomes firmly anchored against upward movement
due to considerable frictional restraint between the packing
elements and the surrounding well bore wall.
As previously noted, the difference in seal dimensions between the
piston 129 and the mandrel assembly 107 on the one hand, and the
seal collar 153 and the tube 112 on the other, are such that a
greater volume of well fluids is drawn in through the screen sub 16
than is required for the displacement volume of the pump chamber
131, with the result that during each downward or suction stroke of
the housing 105, a certain amount of excess fluid is discharged
back to the well annulus via the screen to backflush and purge the
openings in the screen element 178. Thus it is practically
impossible for the screen to become plugged and result in a misrun
as the case for prior art devices of this type.
When a predetermined maximum inflation pressure has been developed
within the inflatable elements 20 and 20' through operation of the
pump assembly 17 as described above, the inlet valve seat ring 136
will be forced upwardly and away from the mandrel shoulder 147 on
each subsequent upward movement so that all the fluids in the
chamber 131 are vented through the screen sub lack to the well
annulus, rather than being displaced into the inflation passage
118. Since the amount of force required at the surface to lift the
pipe string 10 is directly related to the pressures developed
within the chamber 131 and resisting upward movement of the piston
129, the amount of such force will increase until the pressures
generated during the upward movements reach a magnitude sufficient
to force the seat ring 136 upwardly, after which the force required
to lift the pipe 10 during each pumping stroke will remain
substantially constant. Thus the weight indicator at the rig floor
can be observed by the tool operator and gives a positive
indication of the performance of the downhole tools. That is to
say, when the weight value stops increasing during each upward
movement of the pipe string, the operator is assured that the
packing elements 20 and 20' are fully expanded to the proper
inflation pressure and can discontinue further operation of the
pump assembly 17.
It should be noted at this point that upward movement is
appropriate to open the pressure equalizing and packer deflating
assembly 18, whereas downward movement is used to open the test
valve 13. However, the operation of the respective hydraulic delay
pistons 195 and 233 of these tools enables the pump assembly 17 to
be actuated by repetitive downward and upward movements without
opening the test valve or the equalizing valve because such
movements occur during substantially lesser time intervals than is
required for the delay pistons to meter to a released position.
Thus the test and equalizing valves remain closed during operation
of the pump assembly 17. Also, as previously mentioned, should an
excessive squeeze fluid pressure tend to develop within the
isolated interval of the well bore between the packing elements 20
and 20' due to expansion thereof subsequent to obtaining effective
sealing action against the well bore wall, the excess pressure
causes upward movement of the bleed valve element 249 so that the
pressure is vented to the well annulus above the upper packing
element 20 through the side ports 250. Of course the valve element
249 is shifted back to the lower closed position as the tester
valve 13 is opened to initiate the test.
When it is desired to open the tester valve 13, the weight of the
pipe string 10 is imposed upon the tools for the length of time
necessary to overcome the hydraulic delay section 226. The mandrel
210 moves slowly downwardly during this time interval as the
metering piston 233 approaches the enlarged diameter portion 235 of
the chamber 234, and then moves rapidly downwardly to its fully
contracted position. The valve heads 213 and 213' are thereby
positioned below the test ports 220 and 218 to open a flow path
through the sample chamber 217 and the mandrel ports 221 into the
pipe string 12. Since the pipe string is initially at atmospheric
or other low pressure, formation fluids in the isolated well
interval between the expanded packing elements 20 and 20' will
enter the ports 55 and flow upwardly through the passage 44, the
ports 43, the bore 193 of the flow tube 192, through the central
opening of the pump mandrel assembly 107, the bore 169 of the
screen sub 16, through the pressure recorder carrier 15 and the
excess pressure sub 14, and finally through the test valve assembly
13 into the pipe string 12. After a relatively short period of time
necessary to drawn down the pressure in the interval of the well
bore between the packing elements 20 and 20', the pipe string 10 is
raised to shift the tester mandrel 210 upwardly and close the test
ports 218 and 220. The formation is thereby shut-in to enable
recordal by the gauge in the carrier 15 of pressure built-up data
from which various formation and well fluids parameters can be
determined as will be appreciated by those skilled in the art. Of
course the tester valve can be repeatedly opened and closed as
desired to gather further flow and shut-in pressure information,
and each time the tester is closed a flowing sample of flowing
formation fluids is trapped within the chamber 219. At all times
during the test, of course the straddle bypass formed by the
lateral ports 47, the bore 42 of the flow tube 45, the ports 75,
the annulus space 77 and the later ports 79, remains open to ensure
that the hydrostatic pressure of the well fluids above the upper
packing element 20 is substantially equalized with the
corresponding pressure of well fluids below the lower packing
element 20'. The lower pressure recorder in the carrier sub 28
records the fluid pressure within the isolated interval between the
elements 20 and 20' by virtue of being in communication therewith
via the lateral ports 100, the bore 99 of the flow tube 78 and the
bore 98 of the equalizing valve tube 90. The pressure record
obtained thereby can, of course, be compared with the readings
taken by the upper pressure recorder at 15.
When it is desired to terminate the test, a strain is placed in the
pipe string 10, and the tension is maintained for a time sufficient
to overcome the retarding action of the hydraulic delay piston 195
in the equalizing and deflate valve assembly 18. As the piston 195
reaches the upper end of the chamber 196, the equalizing grooves
203 and 205 are disposed above the respective seal rings 206 and
204 to communicate both the inflation passage 194 and the test
passage 193 with the well annulus above the upper packing element
20 via the ports 201. In this manner, all the various pressures are
equalized with one another, and the packing elements 20 and 20'
will inherently deflate and retract to their original relaxed
dimensions. Upward movement of the entire packing assembly 19 will
cause extension of the lower equalizing sub 23 whereby the
lowermost portion 91 of the inflation passage is communicated with
the well annulus via the ports in ring 92 and the outer member
ports 97. Further upward movement will unset the slips 26 of the
anchor 24 from the well bore wall and cause them to be shifted
inwardly by the slidable spline connections. Thus the equipment can
be withdrawn intact from the well bore when the pressure records
and the sample of formation fluids can be analyzed, or for that
matter can be moved to another level in the well for additional
tests.
Sincer certain changes or modifications may be made by those
skilled in the art without departing from the inventive concepts
disclosed herein, it is the aim of the appended claims to cover all
such changes and modifications falling within the true spirit and
scope of the present invention.
* * * * *