Note: Descriptions are shown in the official language in which they were submitted.
! . I / V
~-`` 2131~
METHODS FOR CONDUCTING
TUBlNG-CONVEllED PERFORAT~G
OPERATIONS IN WELI, BORES
BACK&ROUND OF T~IE INVENTION
Field of The In~ention
The present invention relates to per~oration of well bores and, more specifically, to
the positiolung of perforating guns in the well bore adjacent to the formations to be
10 perforated.
Description of The Related Art
Those skilled in the art will appreciate that so called "tubing-conveyed perforators"
are frequently employed to conduct perforating operations in those deviated well bores where
15 typical cable-suspended or so-called "wireline" perforating guns cannot be effectively
utilized. Moreover, as described in U.S. Patent No. 4,509,604, a technique that is widely ~-
used for completing deviated well bores as well as those well bores which traverse multiple
formations is to dependently couple a tubing-conveyed perforating-and-testing tool to a tubing
joint and progressively lower the tool assembly into a cased well bore by successively
20 assembling a tubing string of sufficient length for dependently positioning the tool assembly
at a selected depth location in the well bore. Once the tool assembly has been positioned, a
packer included with the assembly is expanded into sealing engagement with the casing for
isolating that portion of the well bore lying below the expanded packer. To establish fluid
communication with the earth forrnations adjacent to the isolated well bore portion, shaped
25 explosive charges mounted in one or more enclosed-carrier perforators on the lower end of
the tool assembly are actuated for perforating the steel casing and cement annulus between
the casing and the adjacent borehole wall. Once the perforator has been fired, a test valve
in the well tool is then selectively operated from the surface for controlling fluid
communication between the perforated formation interval and the tubing string ~or conducting
30 various flow and pressure tests of the connate fluids in the isolated earth formations.
It is, of course, essential that these tubing-conveyed tools are accurately positioned
in the well bore before the perforators are actuated. It will be particularly appreciated ~hat
`- 2~.31~9~
~le accurate positioning of those perforators is even more critical where the formation
intervals to be perforated are relatively thin. Typically, a perforating operation is carried out
by referring to logs previously made in that well bore which show pararneters of the earth
formations traversed by the borehole as well as the precise upper and lower deptn boundaries
5 of those formations. By consulting such prior logs, these perforators are assembled in
advance with their respective shaped charges being arranged within each of the carriers for
disposing the charges in predetermined depth and orientational relationships with respect to
each of the formation intervals that are to be per~orated once the tool assembly is positioned
at a selected depth location in that well bore. In addition, the tubing string is arranged in
10 accordance with those prior logs to be of suf~lcient length for accurately positioning the
assembled perforating-and-testing tool at that selected depth location. As a matter of
precaution, these prior logs are often typically correlated witn additional measurements such
as may be obtained by moving a typical wireline logging tool through the assembled tubing
str~ng to verify that the perforators carried by the tubing-conveyed tool assembly have been
15 correctly positioned in relation to the earth forrnations which are to be perforated.
Various techniques have been employed heretofore for reliably identifying the earth
formations to be perforated as well as for accurately positioning the tubing-conveyed
assembly that is to be employed. Typically, a prior so-called "collar log" of the existing
well bore casing is employed for determining the overall length of the tubing string required
20 to situate the perforating-and-testing tool assembly at a predetermined depth once the ~ubing
string has been assembled. The positioning of the tubing-conveyed perforating-and-testing
assembly in relation to the forrnations to be subsequelltly perforated has been carried out
heretofore by employing a wireline logging tool equipped with a typical radiation detector
which is responsive to one or more radioactive charac~eristics of the earth formations
25 penetrated by the well bore. This logging tool is moved through the tubing string supporting
the tool assernbly and temporarily positioned just above the tubing-conveyed tool assembly
for determining whether or not the perforating guns are adjacent to those earth formations
which are to be perforated.
If desired, the tubing string may also be assembled with one or more so-called
3Q "pup joints" or shortened joints of tubing installed at selected locations in the tubing string,to
2 1 ~
_rve as distinctive markers that will be readily detected if the wireline logging tool is also
equipped with a collar locator for providing additional signals which will verify the position
of the logging tool as it is moved through the tubing string supporting the tubing-conveyed
tool assembly.
Another cornmon technique is to place detectable devices such as radioactive
markers or tags at selected depth locations which having a Icnown relationship with respect to
the formations which are to be perforated. Such radioactive tags or markers may take the
forrn of radioactive markers or so-called "pip tags" which are normally taped at known
locations on selected casing joints of casing before the casing string is assembled. In this
manner, after the casing string has been progressively assembled and lowered into the
borehole, the radioactive pip tags will be positioned at predetermined depth locations in the
well bore and will thereby provide distinctive reference points in the well bore that can be
readily detected by typical radiation detectors. Regardless of which of the various techniques
are employed for providing distinctive depth indicators or markers in a well bore, positioning
of tubing-conveyed perforating-and-testing assemblies has been carried out heretofore by
moving a wireline logging tool through the tubing string supporting the assembly of tools.
Such wireline logging tools are equipped with a typical radiation detector that responds to
one or more radioactive characteristics of the earth forrnations penetrated by the well bore as
well as showing the depth location of the radioactive markers which have been previously
positioned in the well bore.
In any event, the correlation measurements provided by any of these wireline
logging tools will, of course, necessitate the services of a specializ~d logging truck and a
crew of technicians before another crew of specialists can conduct the perforating operation.
It will be realized that if the initial correlation measurements indicate that the perforating
2S guns on the tubing-conveyed tool have been correctly positioned, the wireline logging tool
can be returned to the surface without undue delay and the perforating operation comrnenced
without further ado. Even should these initial measurements show that the perforators are
positioned only a few feet away from their intended depths, the assembled tubing string can
be readily raised or lowered at the surface as deemed necessary to shift the perforators to
their correct locations in the well bore without having to first return the logging tool to the
~ j,...
2 ~ 9 ~
~rface. So long as the wireline logging tool is still disposed in the tubing string, there is, of
course, no problem in obtaining corroborating verification measurements to confirrn the
positioning of the perforators before the wireline logging tool is finally retumed to the
surface.
On the other hand, it will be appreciated that~ at tirnes, the initial correlation
measurements provided by the wireline logging tool will instead indicate that the perforators
cannot be properly positioned in the well bore without first changing the overall length of the
supporting tubing string. This latter situation will frequently occur in deviated well bores
having substantially horizontal intervals since significant changes in the overall length of the
tubing string are often required to make even minor adjustrnents in the positions of the
perforators in relation to the formation intervals to be perforated. Should it be determined
that such adjustments must be made, the wireline logging tool must, of course, be
temporarily removed from the well bore before tubing joints can be added to or removed
from the tubing string to adjust the overall length of the tubing string. This will, therefore,
necessitate the subsequent return of the logging tool back through the tubing string for
obtaining additional correlation measurements before the perforating-and-testing operatiorls
can be safely conducted. It will be realized that even if the logging tool can be readily
returned through the tubing string, these further correlation measurements will elltail
unplanned expenses such as additional stand-by charges since the logging crew must remain
~0 idle at the well site while the overall length of the ~ubing string is being modified. Those
skilled in the art will also appreciate that there will be increased time delays every time that
the wireline logging tool must be moved back through a tubing string which has one or more
portions that are disposed in one or more significantly-inclined intervals of a particular well
bore which is to be perforated with a tubing-conveyed perforator.
Accordingly, it is an object of the present invention to teach new and improved
methods for employing tubing-conveyed well perforators for accurately perforating cased
well bore intervals at a minimum cost.
It is a further object of the present invention to provide new and improved methods
for reliably positioning typical tubing-conveyed well tools in well bores for subsequently
conducting one or more completion opera~ions in relation to selected formations traversed by
2 ~
..le well bore.
It is an additional object of the present invention to disclose new and improvedmethods for accurately positioning tubing-conveyed well bore perforating apparatus at
selected depth locations in deviated well bores without experiencing needless delays
5 whenever adjustrnents must be made in the position of the apparatus and thereafter actuating
the perforating apparatus with the full assurance that the resulting perforations will be
correctly placed at those selected depth locations.
SUMMARY OF l~IE I~TENTION
These and other objects of the invention are attained by providing new and
improved methods for accurately positioning tubing-conveyed well bore apparatus in a well
5 bore without having to employ wireline logging tools. In practicing the invention, a shoulder
is arranged to support a retrievable measurement-while-drilling (MWD) tool having a
radiation detector at a selected location in a tubing string carrying a tubing-conveyed tool
such as a perforator with shaped explosive charges. Once a tubing string has been lowered
into a well bore and the MWD tool positioned on itS supportive shoulder, the MWD tool is
10 operated to transmit acoustic signals through the tubing string representative of the
radioactive characteristics of either a radioactive marker at a known depth or the formations
adjacent to the MWD tool. The acoustic signals are correlated to deterrnine the location of
the tubing-conveyed tool within the well bore. The correlated data is then used for
detemlining how to adjust the tubing string to accurately position the tubing-conveyed tool at
15 a proposed depth location in the well bore.
BRIEF DESCRIPIION OF THE DRAW~GS
The particular features of the invention are set forth in the appended claims. I`he
practice of the new and improved methods of the invention, together with ~urther objects and
various advantages thereof, may best be understood by way of the following description of
20 typical apparatus as it may be employed for carrying out the methods of the invention as
depicted in the accompanying drawings, in which:
FIGURE 1 illustrates a preferred embodiment of typical well bore apparatus which may
be successfully employed to carry out the new and improved methods of the present
'~ 31~
ention; and
FIGURES 2-5 schematically depict the sequential positions of the well bore apparatus
shown in FI&URE 1 showing the successive steps of the preferred maMer of employing that
apparatus to practice the methods of the present invention for conducting a perforating and
5 testing operation in a cased well bore
DETA~ILED DESCRIPl'ION OF THE PREFERRED EM[BODIMENT
Turning now to FIGURE 1, as indicated generally at 10, a typical tubing-conveyedperforating-and-testing tool (such as the tool assembly fully described in U.S. Patent No.
4,509,604 which is hereby incorporated herein by reference) is depicted as that tool assembly
will appear while suspended in a cased well bore 11. As is typical, the tool assembly 10 was
previously coupled to the lower end of a joint or stand of well tubing and the tool assembly ~:
was then progressively lowered into the cased well bore 11 as an elongated tubing string 12
was successively assembled from tandernly-coupled joints with a combined overall length
15 suff1cient for positioning the tool adjacent to a selected earth forrnation, as at 13, containing
producible coMate fluids. The tubing-conveyed perforating-and-testing tool 10 preferably
includes a full-bore reversing valve 14 tandemly coupled between the lower end of the tubing
string 12 and the upper end of a full-bore test valve 15. The test valve 15 is, in turn,
coupled to the upper end of a tubular mandrel of a full-bore packer 16 which is arranged for
20 dependently supporting a tubing-conveyed perforator such as shown generally at 17. As is
typical, the perforator 17 is preferably dependently coupled to the lower end of the packer 16
by a so-called "safety joint" 18 placed so that the perforator 17 is below the rig floor when ~ .
the perforating guns are arrned. A slotted section of pipe 19 is also typically coupled
between the perforator 17 and the safety joint 18 to facilitate the entry of connate fluids into
25 the tubing string 12 once the perforator has been actuated.
Accordingly, in practicing the invention, the packer 16 may be a typical filll-bore ;
packer including normally-retracted slips and expandable elastomeric packing elements which
are each operable to be shifted outwardly against the internal wall of the casing 111 at a
selected depth location just above the forrnation 13. In a similar fashion, as an example of
30 exemplary apparatus for practicing the new and irnproved methods of the invention, the
,~ersing valve 14 represented in FIGURE 1 is preferably a selectively-operable -full-bore,
pressure-controlled reversing valve. As is typical, the reversing valve 14 is fully operable
for selectively controlling comrnunication between the internal bore of the tubing string, as at
12, and the annulus of the well bore, as at 11, by means of controlled pressure changes in
the fluids in the annulus and the tubing string. Those skilled in the art will recognize, of
course, that various types of typical full-bore reversing valves can also be readily employed
as well without departing beyond the scope of the present invention disclosed and claimed
herein.
Similarly, in carrying out the methods of the present invention, it is preferred to
utilize the repetitively-operable full-bore test valve 15 fully disclosed in U.S. Reissue Patent
No. 29,638 which is also incorporated herein by re-ference. As described in that reissue
patent, the test valve has a rotatable ball valve member (not illustrated in the present
drawings) which is selectively rotated between its opened and closed positions in response to
controlled pressure changes of the fluids in the annulus of the well bore 11 and the fluids in
the tubing string 12 for controlling communication through the tubing-conveyed perforating-
and-testing assembly 10 and its supporting tubing string 12. Here again, it must be
understood that in lieu of using the full-bore test valve 15 described in the aforementioned
reissue patent, other types of test valves can be employed for practicing the methods of the
present invention. For e~ample, the new and improved methods of the invention may also
be successfully practiced by employing a simpler test tool (not illustrated in the present
drawings) such as those having a glass disc or other frangible barrier initially blocking the
axial bore of these simpler tools until the barrier is broken by dropping a so-called "drop
bar" through the tubing string 12 whenever communication is to be permanently established
through the tubing string.
The particular perforator 17 which is to be utilized in successfully practicing the
methods of the invention can be any one of the typical tubing-conveyed perforators currently
in use in the industry. For example, the perforator 17 can be arranged in accordance with
the new and irnproved perforator disclosed in U.S. Patent No. 4,509,604. As schematically
depicted in FIGURE 1, the perforator 17 typically has a so-called "firing head" 20 coupled
to the upper end of an assembly of one or more enclosed tubular carriers, as indicated
2131~ 9~
O nerally at 21 and 22, which are respectively arranged for supporting therein a plurality of
shaped explosive charges as shown at 23 and 24 in FIGURE 2. As fully described in the
last-cited patent, the filring head 20 is operatively arranged as seen in FIGURE 2 for
detonating a typical blasting cap 25 coupled to a length of flexible detonating cord, such as at
26, which is disposed through the enclosed carriers 21 and 22 and cooperatively arranged
within detonating proximity of each of the several shapPd charges as at 23 and 24. In the
preferred manner of practicing the methods of the present invention, as described in the last-
ited patent, the firing head 20 is arranged so that it can be selectively operated from the
surface by controlled pressure variations in the fluids in the well bore 11 and the tubing
string 12. If the configuration of the tubing string 12 will permit, the firing head 20 is also
arranged to be fired by dropping a weighted so-called "drop bar" (not illustrated) into the
tubing string when it is reasonably assured that this drop bar will be able to strike the firing
head with suf~1cient impact to detonate the blasting cap 25.
Since the present invention relates to new and improved methods for accurately :.
positioning tubing-conveyed well bore tools such as the depicted perforating-and-testing tool
assembly 10, it must be understood that the successful practice of the invention is wholly
independent of the particular well bore devices, as at 14-26, which may be collectively
employed for assembling the combined perforating-and-testing tool 10 depicted in FIGURE
1. Those skilled in the art will appreciate that there is a wide variety of typical well bore
devices, such as at 14-26, which are readily available. Accordingly, as will subsequently .
become apparent, it will be appreciated that a full and complete understanding of the practice
of the present invention does not require a detailed description or drawings of any of the well
bore devices 14-26 which may be selected and readily incorporated into the tool assembly 10
by anyone skilled in the art for successfully practicing the methods of the present invention.
Nevertheless, irrespective of the particular well bore devices 14-26 which have
been selected for inclusion in the tool assembly 10, to practice the methods of the present
invention it is essential that a tool-positioning device, such as a tubular sub or landing nipple
30, be located in the tubing string 12 at a known spatial relationship in relation to the
perforator 17 that is included in the tool assembly. As is typical, the tubular landing nipple
30 includes means, as generally indicated at 31 in FIGURE 2, such as a reduced-diameter
2~ 3~3'~
A~ermediate portion in the axial bore of the tubular sub for defining an upwardly-~acing
internal shoulder or inwardly-projecting abutment cooperatively configured for receiving a
matching shoulder on a MWD tool such as the MWD tool shown at 32.
To practice the methods of the present invention, it will, of course, be recognized
S that in order for the MWD tool 32 to be capable of being safely moved through the tubing
stLing 12, the external diameter of the tool must be somewhat less than the internal diameter
of the tubing string. Accordingly, to practice the methods of the present invention, it is
preferred that the MWD tool 32 is the new and improved reduced-diameter MWD tool that is
fully described in U.S. Patent No. 4,914,637 which is hereby incorporated herein by
10 reference. As pointed out in that patent, that particular MWD tool, as at 32, is not nearly as
complic~ted as conventional MWD tools which are typically coupled into a string of drill
pipe and drilling collars and arranged for providing selected measurements during the course
of drilling a borehole with a rotary bit. Accordingly, it has been found that the reduced-
diameter MWD tool 32 depicted in FIGURE 1 uniquely lends itself to being readily arranged
15 for safe passage through a tubing string such as at 12. It will, of course, be recognized that
the MWD tool 32 can be readily arranged by those with only routine skill in the art to carry
a sensor package, as indicated generally at 33 in FIGURE 2, which includes a variety of
typical sensor devices such as gamma-energy radioactivity detectors as well as their
associated electronic circuitry, with this combined sensor package being located in an
20 enclosed pressure-balanced housing 34 which, as depicted in FIGURE 1, is preferably
arranged on the lower end of the MWD tool.
As fully described in U.S. Patent No. 4,914,637, it will be appreciated that as
illustrated in FIGURE 2B in that patent, the landing nipple 30 and the complementary
shoulders indicated generally at 31 can be arranged for orienting the MWD tool 32 in a
25 known angular relationship with respect to the perforator 17 should it be desired that the
sensor package 33 further include sensors capable of monitoring the angular orientation of
the MWD tool 32 in relation to the orientation of the firing axes of the shaped charges Z3
and 24. It must be recognized, however, that the successfill practice of the method of the
present invention does not require that the MWD tool 32 must always be oriented in a known
30 angular relationship unless a particular perforating-and-testing operation which is to be
`` æ~3,~9,~,~
r~rforrned necessitaLes that the shaped charges 23 and 24 are aligned in a particular
orientation.
Turning now to FIGURES 2-5, schematic representations of the perforating-and-
testing tool 10 are respectively depicted in those drawings as the assembled tool is
successively employed to practice the preferred steps of methods of the present invention to
perforate a selected earth forrnation as at 13. As represented in FIGURE 2, individual joints
or stands of well tubing have been successively coupled to the upper end of the tubing string
12 and progressively lowered from the surface into the cased well bore 11 until the combined
length of the tubing string was sufficient for positioning the perforator 17 depending ~rom the
lower end of the tool assembly 10 adjacent to the earth fonnation 13. It will be noted that as
depicted in FIGIJRES 1-5, the landing nipple 30 is preferably coupled to the lower end of
the tubing string 12 so that the MVVD tool 32 will be offset only a mir~imal distance above
the perforating-and-testing tool assembly 10. With such minimal spacing, it will be
appreciated that the sensor package 33 will be better able to provide real-time measurements
representative of the characteristics of the particular earth formation, as at 13, that the
perforator 17 is then facing. It will, however, be recogni~ed that the particular spatial
relationship of the sensor package 33 and the perforating-and-~esting tool 10 is not of a
critical importance to the successful practice of the new and improved methods of the present
invention since the tubing string 12 can be moved upwardly and downwardly from the
` surface whenever it is necessary to determine various forrnation characteristics as well as to
accurately locate the upper and lower boundaries of any given earth forrnation. Accordingly,
those skilled in the art will appreciate that the successful practice of the present invention
requires only knowing the precise spatial relationship between the sensor package 33 and the
perforators 17 whenever the MWD tool 32 is seated in the landing nipple 30.
In FIGURE 2 the perforating-and-testing tool assernbly 10 is depicted as the tool
assembly is being lowered into the well bore 11. At this point in the operation, the reverse
circulating valve 14 is in its open position to allow the tubing string 12 to be progressively
filled with the fluids (typically a salt water brine solution) in the well bore 11 as the tool
assembly 10 is being lowered to its selected depth location. At this time, the test valve 15 is
in its closed position. Although the MWD tool 32 is seen in FIGURE 2 it should be
'~ i 9 ~
~ .,ognized that, as a matter of choice, it may be desired to position the MWD tool on the
landing nipple 30 after the entire tubing string 12 has been assembled. In that situation, the
MWD tool 32 will be spared from any rough handling that it might otherwise encounter as
the tubing string 12 is assembled. The MWD tool 32 can, of course, be subsequently
transported to its selected depth location by releasably coupling a typical wireline overshot
(not illustrated in FIGURE 2) to a matching upstanding fishing neck 35 on the upper end of
the MWD tool and lowering the MWD tool through the tubing string 12 until it has reached
its operating position defined by the engagement of the opposing shoulders 31 on the landing
nipple 30 and body of the MWD tool. Nevertheless, it will be recognized that it is a only a
matter of choice whether the MWD tool 32 is alternatively initially positioned on the landing
nipple 30 with the mating shoulders 31 cooperatively engaged and the tool transported into
the well bore 11 as the tubing string 12 is being progressively assembled.
As shown in FI&URE 3, the perforating-and-testing tool assembly 10 has been
positioned at a selected depth location in the well bore 11 as is determined by the combined
lS length of the tubing string 12 which has been assembled at that time. The test valve 15 is
still closed and, as depicted, the packer 16 has not been set. It should be noted that if
desired to protect various earth formations from damage, the full bore packer 16 could be set
if deemed best for isolating that portion of the well bore below the present depth location of
the tool assembly 10. As indicated by the flow arrows 40 in FI&URE 3, a fluid, such as a
typical brine solution, is then pumped into the tubing string 12 by operating suitable surface
equipmenc (not illustrated) to carry the tluid downwardly through the tubing string and out of
the still-open ports of the circulating valve 14 into the aMulus of the well bore 11 from
where the fluid is then returned to the surface. In this manner, as fully described in the
above-cited U.S. Patent No. 4,914,637, the downward flow of the fluid through the tubing
string 12 will be effective for initiating the operation of the MWD tool 32 for producing one
or more detectable acoustic signals which will be transmitted through the downwardly-
moving fluid to typical signal-detecting equipment (not illustrated) that is coupled to the
upper end of the tubing string for decoding the acoustic signals which are representative of
the real-time measurements produced by the sensor package 33.
It will, of course, be appreciated that the successful practice of the present
11
., ~ , : ,, ,
, ~ , , .
2~.31~9~
i.lvention is not limited to positioning the tool assembly 10 either at its final depth location or
at one or more intermediate depth locations before the MWD tool 32 is operated. The
MWD tool 32 may be operated any number of times at one or more interrnediate depth
locations while the tubing string 12 which has been assembled to that point is moving or
5 stationary so that the sensor package 33 can provide one or more sets of measurements that
may be utilized for verifying the current depth location of the tool assembly 10 and the
nature of the earth forrnations which are then imrnediately adjacent to the sensor package.
Nevertheless, as shown in FIGURE 4, once the tubing string 12 is believed to have
been fully assembled so as to accurately position the perforator 17 adjacent to the selected
10 formation 13 to be perforated, the downward flow of fluids, as indicated at 45, through the
assembled tubing string is employed for operating the MWD tool 32 to determine the nature
of the formation interval that is penetrated at that particular depth location in the cased well
bore 11. By including a typical radiation detector in the sensor package 33, the output
signals provided by the MWD tool 32 can be effectively utilized for providing surface
15 indications that are representative of the radioactivity characteristics of the formation 13. It
will also be recognized that, if desired, this typical radiation detector in the sensor package
33 can also be used to sense the proximity of the detector to one or more radioactive tags, as
at 50, which have been previously placed at one or more selected depth locatiorls in the well
bore 11. In any case, by simply correlating those surface indications with previous logs
20 which have been obtained of the various formations at different depth locations in the well
bore 11, as well as of radioactive tags, as at 50, a determination can be readily made
whether or not the perfarator 17 has been accurately located with respect to the selected
formation 13.
Should these initial measurements show that the perforator 17 is not precisely
25 located at its intended depth, it is quite convenient, of course, to simply raise or lower the
upper end of the tubing string 12 at the surface for whatever distance that may be required to
bring the per~orator to that depth. It will be fully appreciated by those skilled in the art that
since the MWD tool 32 will rernain in its depicted operating position, the tubing string 12 .
can be carefully shifted from the surface while a series of real-time measurements are
30 transmitted to the signal-detecting equipment (not illustrated in the drawings) located at the
12
'~ 31~9~
;,~rface. Moreover, in sharp contrast with the time-consuming (and sometimes imprecise)
prior-art depth-correlation techniques with typical wireline logging tools which require the
removal of the logging tools from the well bore 11 before any changes can be made in the
overall length of the tubing string, in practicing the present invention, the overall length of
5 the tubing string 12 can be readily increased or decreased without ever having to remove the
MWD tool 32. It will, of course, be recognized by those with skill in the art that by simply
observing the various real-time measurements provided by the MWD tool as the tubing string
12 is being shifted, the overall length of the tubing string can be quickly modified as deemed
necessary; and then the tubing string can thereafter be incrementally positioned both
10 upwardly and downwardly as may be necessary for locating the perforator 17 at the precise
depth for eff1ciently perforating the formation 13. It should also be recognized that so long
as the MWD tool 32 is at its location depicted in FIGURE 4, these critical measurements can
be readily obtained until the tool assembly 10 is correctly positioned and the perforator 17 is
in readiness to be actuated.
Turrling now to FIGURE S, the perforating-and-testing tool 10 is depicted after it
has been positioned so as to accurately locate the perforator 17 in its intended position before
being actuated. At this time, the downward circulation of brine, as previously shown at 45
in FIGURE 4, has been discontinued. As schematically depicted in FIGURE S, a typical
overshot or grapple SS which is dependently supported on a suspension line or so-called
20 "sliclc line" 56 spooled on a winch (not illustrated) at the surface is then lowered into the
tubing string 12 and maneuvered as needed -for securing the grapple to the upstanding fishing
neck 35 Ol1 top of the MWD tool 32. As is typical, once the fishing neck 35 has been
engaged, the winch carrying the suspension line 56 is then operated for returning the MWD
tool 32 to the surface. If it has not been previously set, the full-bore packer 16 is then
25 operated for expanding the elastomer~c elements on the packer into sealing engagement with
the adjacent wall of the casing 111.
Once the MWD tool 32 has been returned to the surface, it is typically preferred to
replace the fluid, such as brine, that has been pumped through the tubing string 12 to operate
the MWD tool. As represented by the flow arrows 57, replacement Gf the brine in the
30 tubing string 12 is conveniently accomplished by pumping a suitable pressure-control fluid
13
C~13~9~
~ ch as diesel oil into the tubing string while the circulating valve 14 is still open. This
circulation will, of course, serve to displace at least some of the brine through the still-open
ports of the circulating valve 14 and out into the annulus of the well bore 11. Once it is
believed that the diesel oil has displaced a sufficient amount of the brine from the tubing
5 string 11 to reduce the hydrostatic head of the fluids in the tubing string below the
anticipated formation pressure of the connate fluids in the formation 13, the circulating valve
14 is then operated for closing itS outer ports; and the tool assembly 10 will then be in
readiness for commencing the perforating operation.
At this pOilt, the test valve 15 is operated as previously described as required for
10 opening fluid cornrnunication through the tubing string 12 to the isolated well bore interval
lying below the expanded full-bore packer 16. Opening of the test valve 15 will also be
effective for making the upper end of the finng head 20 accessible from the surface by way
of the axial bore through the tubing string 12. Thus, as previously discussed, the perforator
17 is then fired either by controlling the pressure differential between the axial bore of the
15 tubing string 12 and the annulus of the well bore 11 or by dropping a weighted drop bar (not
seen in the drawings) through the tubing string for striking the impact-responsive actuator on
the firing head 20.
Once the perforating operation has been completed, the testing valve 15 is then
operated in the typical fashion for conducting one or more pressure-testing operations of the
20 connate fluids that are produced upon opening of tne test valve. When it is desired to
recover a sample of these fluids, the testing valve 15 can, of course, be left open as
necessary for bringing any connate fluids which may have entered the tubing string 12 to the
surface. Those skilled in the art will obviously appreciate that one or more various pressure
and flow tests may be perfonned while the tool assembly 10 remains in the operating
25 position depicted in FIGURE 5. The nature and number of such tests are, of course, well
beyond the scope of the new and improved methods of the present invention. In any event,
once these tests have been conducted, tne tool assembly 10 is operated ~or releasing tne
packer 16 and then progressively raising the tu'oing string 12 and successively removing one
or more joints or stands of the hlbing until the tool assembly 10 has been returned to the
30 surface.
14
2~ 31~9~
Accordingly, it will be appreciated from the preceding description that the new and
improved methods of the present invention provide techniques ~or accurately locating tubing-
conveyed well bore apparatus such as the combined perforating-and-testing tool 10 in a well
bore as at 11. As described, the methods of the invention are successfully carried out by
S first positioning a reduced-diameter MWD tool 32 at a selected location in the tubing string
12 which is arranged to be assembled for positioning the perforating-and-testing tool 10 at a
selected depth location in a well bore. The MWD tool 32 is then operated for obtaining
signals representative of the measurements provided by radiation-detecting sensing means on
the MWD tool 32 which are representative of the radioactivity characteristics of either one or
10 more radioactive markers that were previously placed at known depth locations in the well
bore or the earth formations adjacent to the MWD tool. Those representative measurements
are then used to accurately determine the depth location of the perforating-and-testing tool 10
so that the perforator 17 carried thereby can be positioned correctly to assure the perforation
of a chosen earth forrnation as at 13.
While only a particular mode of practicing the present invention has been shown and
described herein, it is apparent that various changes and modifications may be made without
departing from the broader aspects of this invention; and, therefore, the aim in the appended
claims is to cover all changes and modifications that fall within the true spirit and scope of
this invention.
