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Патент USA US3451270

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June 24, 1969
A_ p, Rmx-WER»l JR" El’ AL
Filed Nov. 29, 1967
June 24, 1969
Filed Nov. 29, 1967
. ?'MlJw-THC'LC.
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United States Patent O ” ICC
Patented June 24, 1969
uring surge pressure of drilling mud in an earth bore
hole as the drill string is being run down into the mud
Albert P. Richter, Jr., and James D. Bruner, Houston,
Tex., assignors to Texaco Inc., New York, N.Y., a
corporation of Delaware
Filed Nov. Z9, 1967, Ser. No. 686,566
Int. Cl. E211) 29/00
U.S. 'CL 73-152
iilled borehole. The sensor actuates a remotely located
transducer. Electrical signals representative of the surge
pressure beneath the bit are transmitted to a transducer
signal processing circuitry unit and then to a recording
unit, said units being incorporated in the drill string above
3 `Claims
Apparatus for continuously measuring the surge pres~
the drill bit.
Other objects and advantages as well as the various fea
10 tures of novelty which characterize the invention are
pointed out with particularity in the claims annexed here
with and forming part of the specification. For a clearer
sure developed when a drill string having a drill bit at the
end thereof is run into an earth borehole ñlled with drill
understanding of the invention, its operating advantages
surge pressure are transmitted from the pressure trans
Brief description of the drawings
and the specific objects attained by its use, reference is to
ing mud. Incorporated in the drill bit per se isA ra? pressure 15 be had to the accompanying drawing ñgures and descrip
tive matter in which there is illustrated and described an
sensing element which actuates a'?ëfñ'öt'ëly located pres
illustrative embodiment and practice of the invention.
sure transducer. Electrical signals representative of the
ducer to a transducer signal pocessing circuitry unit and
FIG. 1 is an elevation View showing a rotary drilling
then to a recording unit, said units being incorporated in 20 apparatus
as it is being lowered back into an earth bore
the drill string above the drill bit.
hole filled with drilling mud; said apparatus including
the surge pressure measuring apparatus in accordance
with the present invention.
Background of the invention
FIGS. 2a, 2b and 2c are cross-sectional elevation views
of different sections of the lower end of the drilling appa
This invention pertains in general to a method and
ratus of FIG. l and including the rotary drill bit of the
apparatus for detecting, measuring and recording the
apparatus; FIG. 2a showing the uppermost section, FIG.
surge pressure below a drill bit at the end of a drill
2b the next lower section, and FIG. 2c the lowermost sec
string as the drill string is run downwardly into an earth
tion below that of FIG. 2b.
borehole filled with drilling mud or ñuid.
One important parameter in connection with the mak
Detailed description of the invention
ing of a borehole in the earth for the purpose of seeking
figures like elements or components are
subsurface oil, gas or minerals is the magnitude of the
designated by the same reference numbers throughout.
surge pressure below the drill bit. While the borehole is
In FIG. l there is illustrated a drill string designated
being made in the earth by a rotating drill bit, the bore
hole has drilling mud circulating therein. However, from
generally by the reference number 10, which drill string
changed. Upon lowering the drill string back into the mud
into an earth borehole 14 which traverses various earth
is made up of, among other things, a series of drill pipes
time to time, for various reasons, the rotation of the
coupled end-to-end. Located at the lowermost end of drill
drill bit is stopped and the circulation of the drilling
mud is also stopped in order to raise the drill string, hav 40 string 10 is a conventional rotary drill bit designated, gen
erally, by the reference number 12. As suggested in FIG.
ing the drill bit at the end thereof, out of the borehole.
1, drill bit 12 at the end of the drill string is being lowered
For example, it may be that the drill bit has to be
formations and the borehole 14 is ñlled with drilling mud
filled borehole it often happens that the drill string is
dropped rapidly through an appreciable distance and there 45 or -drilling fluid. The drilling mud being designated gen
erally by the reference number 14a. As shown in FIG. 1
occurs immediately below the drill bit a rather high surge
the drill bit and drill string, although well down in the
pressure. This surge pressure is comprised of among
mud ñlled borehole, have not as yet reached the bottom
others three components; one, the pressure produced by
the bit acting as a piston in the borehole; two, the pressure
Referring now to FIG. 2a there shown is a capsule
required to get the mud displaced by the drill string into 50
designated generally by the reference number 16. As in
motion; and, three, the pressure necessary to overcome
dicated `by the label, capsule 16 houses a recording unit
the viscous drag of the mud column. If these components
and associated circuitry. Capsule 16 is a sealed container
of pressure are high enough, damage to the surrounding
adapted to withstand pressures of about 14,000 lbs. per
formations would result and would possibly fracture the
formation with the consequent loss of circulation of the 55 square inch, or more as required. As shown recorder cap
sule 16 is mounted coaxially within a special sub 18 which
drilling mud. In some cases the pressure that will fracture
a formation is very near the pressure produced by the
mud weight necessary to prevent a blowout. In such cases,
the surge pressure is a critical item indeed. Hence, it is
desirable to measure the magnitude of the surge pressure. 60
Summary of the invention
is a conventional drill collar that has been hollowed out
for the purpose of receiving capsule 16. Capsule 16 is sup
ported within special sub 18 by means of a plurality of
longitudinal members 20 or runners which are welded to
the outside surface of capsule 116 along substantially the
entire length thereof and to the special sub 18. Capsule
16 is closed at its upper and lower ends by two end caps
One object of the invention is to provide a method and
22 and 24, respectively, or -bull plugs as they are often
apparatus for determining the surge pressure below a
called. Details of the construction of capsule 16 are dis~
drill bit.
65 closed in more detail in U.S. patent application Ser. No.
Another object of the invention is to prevent forma
674,335 entitled “Logging While Drilling System” filed
tion fracturing and loss of circulation of the drilling mud
Oct. 10, 1967 in behalf of Albert P. Richter, Jr. and
while running the drill string into a mud filled borehole
James D. Bruner. As indicated in FIG. 2a, end cap 24
in the earth.
has a threaded aperture therethrough which receives a
In accordance with an illustrative embodiment and 70 threaded conduit 26. The conduit 26 has an annular
practice of the invention there is incorporated in a drill
groove formed on the outside surface thereof and this
bit at the end of a drill string a pressure sensor for meas~
groove contains a. sealing O‘-ring 28.
Coupled to the lower end of the special sub 18 by
this force to the transducer 56. Transducer 56 may, for
example, include a strain gauge conñguration. The sig
nals from the transducer 56, which are representative of
the surge pressure transmitted through the oil filled col
means of conventional API tool thread is another special
sub 30. Mounted coaxially within special sub 30 is an
other sealed capsule 32 similar to capsule 16. Capsule 32
as indicated by the labeling contains transducer signal
umn 54, are thence transmitted via the conductors 58 to
capsule 32 and thence in the manner hereinbefore ex
processing circuitry. Capsule 32 is mounted on welded
runners 34 to the special sub 30 in the same manner as
plained to the capsule 16 whereat they are recorded. Thus
as the drill string and bit are passed downwardly through
the mud lilled borehole there is obtained simultaneously
capsule 16 is mounted by means of the runners 20 to the
special sub 18. Capsule 32 is provided with two end caps
3‘6 and 38 or bull plugs, the end caps 36 and 38 being 10 a record of the surge pressure below the drill bit corre
at the upper and lower ends of capsule 32. More details
lated with the velocity and depth of the drill bit in the
on the construction and arrangement of capsule 32 is dis
borehole. The velocity being recorded by means of the re
closed in the aforementioned U.S. patent application Ser.
c-order 60. Recorder `60 shown in FIG. 1 is a velocity
No. 674,335.
measuring device for the purpose of measuring how fast
End cap 36 as shown in FIG. 2b has an aperture there 15 drill string 10 is advancing downwardly into borehole 14.
through which receives the conduit 26. Conduit 26 carries
While a specific embodiment and practice of the inven
therewithin electrical conductors 42, which conductors
tion has been shown and described in detail to illustrate
transmit signals from the transducer signal processing cir
cuitry -within capsule 32 to the capsule 16 which contains
a recording unit such as a magnetic tape recorder and as
the application of the principles of the invention, it is to
be understood that the invention may be embodied other
sociated circuitry. As shown in FIG. 2b end cap 38 has
a threaded aperture therethrough which receives the end
wise without departing from such principles.
What is claimed is:
1. Apparatus for logging at least one parameter deter
mined in a earth borehole containing drilling mud com
of a threaded oil-filled conduit 44. At the point where
conduit 44 enters the aperture in end cap 38 a pair of
annular grooves is provided in the outside surface of the 25
a drill string having a drill bit at an end thereof;
conduit and these grooves receive the sealing O-rings 46.
means in said drill bit for detecting at least one param
Coupled by means of conventional API tool threads at
eter in the borehole;
the end of special sub 30 is another special sub 48. Cou
means in said drill string for recording the detected
pled to the lowermost end, as shown in FIG. 2c, of specal
sub 48 is the drill bit 12. As shown in FIGS. 2b and 2c 30
said detecting means in said drill bit detecting surge
conduit 44 extends coaxially within special sub 48 from
pressures below the bit as the drill string and bit are
end cap 46 through special sub 48 to the drill bit 12. Drill
passed into the mud containing earth borehole.
bit 12 'has a central opening formed therein for receiving
2. Apparatus for logging surge pressure below a drill
conduit 44. An annular space is formed in the drill bit
bit at the end of a drill string as the string yand bit are
for receiving an `O-ring seal 50. .At the lowermost end of 35 passed into an earth Áborehole containing drilling mud
conduit 44 there is mounted a pressure sensing element,
comprising: a pressure sensing device incorporated in the
or sensor, 52. Pressure sensor 52 may, for example, be a
drill bit and located in the bit so as to sense the surge
diaphragm or piston type of pressure transmitting ele
pressure of «the ‘drilling mud as the bit passes through the
ment. Conduit 44 is ñlled with oil column 54. The oil
drilling mud in the borehole; housing means mounted in
column 54 ñlls the entire hollow in_ner passage of conduit 40 the drill string and including therein a transducer for con
44 from the element 52 in the drill bit at one end to a
verting pressure energy to electrical signals, circuitry for
pressure transducer 56 located at the other end mounted
processing the electrical signals and a recording unit for
in the end cap 38. Coupled to the pressure transducer 56
recording the signals; and, means for transmitting pressure
in end cap 38 are the electrical conductors 58 which
sensed by said device to the transducer.
transmit electrical signals from transducer 56 to the trans 45
3. Apparatus according to claim 2 wherein the pressure
ducer signal processing circuitry. Signals from the trans
duoer signal processing circuitry in capsule 32 are then
transmitted via the conductors 42 through conduit 26 to
the capsule 16 to the recording unit and associated cir
cuitry. With the apparatus, shown more particularly at 50
FIG. 2c, the ‘determination of surge pressure of the drill
ing mud below the bit as the drill string 10 and bit 12
are being lowered into borehole 14 may be determined by
the following method:
As the drill string and bit are lowered into the bore
hole and traverses various earth formations thereof, the
pressure sensing element 52 is actuated by the surge pres
sure of the drilling mud. The element 52 transmits this
force to the oil ñlled column 54 which, in turn, transmits
sensing device includes a piston, and wherein the last
mentioned means is a lluid-ñlled conduit extending from
the piston to the transducer.
References Cited
Arps _____________ __ 175-39
Lyles ___________ __ 73~l52 X
Klotz ___________ _.. 175-48 X
RICHARD C. QUEISSER, Primary Examiner.
JERRY W. MYRACLE, Assistant Examiner.
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