US3336572A

US3336572A - Sonic means and method for locating and introducing equipment into a submarine well

Info

Publication number: US3336572A
Application number: US451955A
Authority: US
Inventors: Peter L Paull; Fontaine C Armistead
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1965-04-29
Filing date: 1965-04-29
Publication date: 1967-08-15
Anticipated expiration: 1984-08-15
Also published as: GB1182758A; NL148709B; DE1756698A1; DE1756698C3; DE1281974B; NL6809245A; NL6711098A; NL148708B; GB1122243A; NO129244B; DE1756698B2

Description

ING

Aug. 15. 1967 A P. L. PAULL ETAL SONIC MEANS AND METHOD FOR LOCATING AND INTRODUC EQUIPMENT INTO A SUBMARINE WELL Filed April 29, 1965 2 Sheets-Sheet l some MEANS-AND Mimi Filed April 29, 1965 CING 2 Sheets-Sheet 2 J/cz A 7; 75

7/ ower Afl/A y 5/ 53 3 I 73 United States Patent Q 3,336,572 SONIC MEANS AND METHOD FOR LOCATING AND INTRODUCING EQUIPMENT INTO A SUBMARHNE WELL Peter L. Paul], Weston, and Fontaine C. Armistead, Darien, Cnn., assignors to Texaco Inc., New York, N. a corporation of Delaware Filed Apr. 29, 1965, Ser. No. 451,955 13 Claims. (Cl. 340-6) This invention relates to deep-water drilling apparatus and, more particularly, to sonic means for locating and providing the entry of equipment, such as a guide conduit into a submarine well.

In deep-Water drilling, a known means for guiding equipment and tools into a submarine well is by the use of guide cables which extend from the underwater wellhead equipment to the drilling vessel. The equipment to be indexed with the submarine well is attached to an equipment bracket which is adapted to be attached to the guide cables such that the bracket and equipment are guided along the cables to the well and the equipment entered therein. The main disadvantage of this arrangement is the large drift caused by strong underwater currents affecting the guide cables and the equipment being guided thereby so that the equipment when adjacent the underwater well may not be in a vertical position conducive to easy entry therein. Another disadvantage is the frequent entanglement of the cables due to the underwater currents or the mishandling thereof.

The guide cables offer a very limited range of drift of the drilling vessel, which range may be exceeded because of storm conditions which would require disconnecting the guide cables from the ship and subsequently relocating and disentangling them.

Guide means other than cables such as a permanently attached conduit extending between the submarine wellhead and the drilling vessel are utilized. However, it has been found that such a conduit offers considerable surface area to the strong underwater currents and accordingly gives rise to considerable drift as well as being a hazard to navigation if the well has to be abandoned.

It is the main object of the present invention to provide sonic means for guiding equipment from the surface to a submarine well so as to provide entry of the equipment into the well.

It is another object of the present invention to provide guide means for equipment to be entered into the well which compensates for underwater currents and accordingly is free from drift.

It is a further object of the present invention to provide sonic means for locating a submarine well and guiding equipment thereto.

It is a further object of the present invention to provide sonic guide means for indexing equipment with a submarine well which is self-centering during guidance, thereby eliminating the necessity of maneuvering the drilling vessel or the derrick means mounted thereon.

The objects of the invention are achieved by a system for guiding equipment during lowering from the water surface so as to enter an underwater well. The system comprises means for generating beams of energy at the underwater well and directing said beams vertically toward the water surface. An equipment bracket is provided which is adapted for lowering from the surface and which carries the equipment to be indexed with the well. Means are located on the bracket for receiving the vertically directed beams. Each beam receiving means is located laterally with respect to the equipment being carried by the bracket as one of the beam generating means is located with respect to the well. The beam receiving means generates electric signals indicative of the amount and direction off-center of said beam receiving means with respect to said beam. Propulsion means are also provided for centering the beam receiving means with respect to the beam in accordance with the electric signals so that the equipment bracket will be guided along the beams when lowered and the equipment carried thereby will be entered into the well.

The objects of this invention are further achieved by apparatus for locating a submarine well and guiding equipment from a vessel on the ocean surface into said well comprising a plurality of ultrasonic transmitting means each located at a different predetermined lateral position with respect to the submarine well. An equipment bracket is provided for carrying the equipment to be lowered to the submarine well which bracket is adapted to be lowered from the vessel. A plurality of ultrasonic receiving means are also provided each located on the bracket at a corresponding lateral position with respect to the equipment carried thereby as one of said ultrasonic transmitting means is positioned with respect to the submarine well. A predetermined one of the ultrasonic transmitting means is energized by switching means so as to produce a relatively low frequency ultrasonic beam directed vertically toward the ocean surface. The ultrasonic receiving means located at the corresponding position with respect tothe equipment carried by the bracket as said relatively low frequency ultrasonic transmitting means is positioned with respect to the submarine well provides an electric signal proportional to the sound intensity received thereby. The vessel is maneuvered until a maximum electric signal is provided. The switching means is activated to change the frequency of the predetermined one of the ultrasonic transmitting means so that the low frequency ultrasonic beam is replaced by a relatively high frequency ultrasonic beam and to simultaneously energize the other ultrasonic transmitting means to produce relatively high frequency narrow angle ultrasonic beams directed toward the ocean surface. The ultrasonic receiving means associated with the predetermined one of the ultrasonic transmitting means is responsive to the relatively high frequency ultrasonic beam. The bracket is rotated about the vertical axis of the ultrasonic receiving means associated with the predetermined one of the ultrasonic transmitting means until the other narrow angle ultrasonic beams are received by their associated ultrasonic receiving means. Each ultrasonic receiving means includes at least three sensing means for sensing the distance and direction off-center of the receiving means with respect to its intercepted narrow angle beam sensed by said sensing means to maintain each of the receiving means centered on its intercepted narrow angle beam. Accordingly the submarine well is located and the equipment bracket is guided along the narrow angle beams when lowered,

thereby introducing the equipment carried by the bracket into the well.

In the specification and claims of this application the term sonic is used in the broad sense of sound and includes ultrasonic.

The above-mentioned and other features and objectives of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing wherein:

FIG. 1 is a schematic diagram of the drilling vessel and the apparatus for locating. and introducing equipment into the submarine well.

FIG. 2 is a bottom view of one of the sonic receiving pods and the associated propulsion units.

FIG. 3 is a schematic bottom view of the sonic receiving pod showing the iso-intensity lines of the sonic field in the sonic beam arranged on the sonic receiving pod when the pod is centered on the beam.

FIG. 4 is a schematic bottom view of a sonic receiving pod similar to FIG. 3 but showing the iso-intensity lines of the sonic field in the sonic beam received by the pod when it is off-center of the beam in the direction shown.

FIG. 5 is a partial schematic block diagram of the ultrasonic transmitter frequency switching means located in the control console of FIG. 1.

Referring to FIG. 1, there is shown a drilling vessel 11 which is anchored by means of anchoring cables 12 and 13 directly over the well bore 16. The wellhead equipment located at the ocean bottom 14 is arranged around the well bore 16 which has been previously drilled and lined with casing 17 which is usually cemented in place. A Wellhead base member 21 is provided which consists of a cement block having a large bottom area to sit on the ocean bottom 14 so as to prevent sinking of the wellhead equipment into the silt or mud which may be present there. The wellhead base 21 contains an opening 22 therethrough by means of which access to the well is provided. The well base 21, in this case, has a member 23 extending from the opening 22 therein towards the ocean surface which member 23 has a funnel shape to aid in the introduction of the equipment into the well.

The base member 21 also has located thereon ultrasonic frequency transmitters 27 and 28. The sonic transmitters 27 and 28 may be one of the well known types of transducers for transmitting ultrasonic sound such as the magnetostrictive or piezoelectric types. Transmitters 27 and 28 are located on the base member equidistant from opposite sides of the funnel shaped member 23 on the same diameter. It should be noted that the sonic transmitters 27 and 28, although shown equidistant from member 23, may be at different distances therefrom and on different diameters. The electrical energization for transmitter 27 is supplied through electrical leads 29 and 32. One lead is for the relatively high ultrasonic frequency energization of transmitter 27 while the other is for the relatively low ultrasonic frequency energization as will be explained later in the application. The energization of transmitter 28 is provided through a lead 34 which along with leads 29 and 32 are formed into a multiconductor cable 36 which extends between the submarine well head equipment and the buoy 31. The buoy is adapted to have an electrical connection made thereat which connects the multiconductor cable 36 to a further multiconductor cable 41 which extends between the buoy 31 and the vessel 11 so that connections can be made to the control console 30 and power supply 72.

The sonic transmitters 27 and 28 each have a diameter of the order of inches. They are designed to operate at approximately one megacycle per second frequency. This combination of transducer size and frequency produces sonic energy which is highly collimated. That is, narrow angle sonic beams are produced which are directed vertically from the submarine wellhead equipment to the surface of the ocean. At the surface, the drilling vessel, in FIG. 1 is shown lowering a guide conduit 42 into the ocean by means of the derrick 43 located thereon. It will be appreciated that the equipment to be introduced into the well does not necessarily require a guide conduit and thus equipment such as a drilling string or logging tool may be lowered and guided by the sonic guide means of this invention directly. An equipment bracket 46 is attached near the lower end of the guide conduit 42. The equipment bracket 46 may be similar to those presently in use in deepwater drilling except for the changes at the lateral ends thereof necessitated by eliminating the usual guide lines and adapting the bracket to operate in conjunction with the sonic guide means. The bracket 46 has receiving pods 47 and 48 mounted at each end thereof. These pods 47 and 48 are adapted to locate and stay centered on the sonic beams generated by the sonic transmitters 27 and 28, respectively. The equipment to be guided to the submarine well is attached to the guide bracket at a point between the receiving pods 47 and 48 which corresponds to the location of the funnel shaped receiving member 23 with respect to the transmitting transducers 27 and 28, respectively. Thus, when the receiving pods 47 and 48 are located directly on the center of their respective beams, the guide bracket is correctly laterally positioned. That is, the equipment being carried by the bracket 46 is vertically aligned with the funnel shaped member 23 at the submarine well so that entry into the well of the equipment being carried by the bracket can be accomplished.

Referring to FIG. '2, it can be seen that a sonic receiving pod 47 or 48 has three sonic receiving transducers 51, 52 and 53 equally spaced about a circle which is concentric with the pod 47 or 48. Since both sonic receiving pods 47 and 48 are exactly the same, only one is shown and described. Associated with each of the sonic receiving transducers 51, 52 and 53 is a propulsion unit 56, 57 and 58, respectively. Each of the units includes a motor 61 and propeller 62 located in a housing which extends radially outward and downward of the sonic receiving pod. The motor driven propeller 62 produces a thrust on the pod which is directed radially of the pod to make correcting adjustments so as to center the sonic receiving pod with respect to the sonic beam. The sonic receiving transducers 51, 52 and 53 may be any of the conventional sonic receivers such as are used in underwater sound apparatus. The particular sonic receivers used should be designed to operate within the frequency ranges of the sonic transmitters used, for example, one magacycle per second frequency. The motors 61 are of the synchronous type such as are used in conventional servo systems. These motors provide an output rotational speed which is proportional to the electrical input signal. The power is applied to the motors 61 and receiving transducers 51, 52 and 53 (FIG. 2) through a power cable 71 extending from the power supply 72 located on the vessel 11 (see FIG. 1). A conductor 73 (see FIG. 2) is also supplied from each of the sonic receiving transducers 51, 52 and 53 to each of the motors 61, respectively, to carry the controlling electrical signal derived from the associated sonic receiving transducer. It will be appreciated that each of the sonic receiving transducers and the associated propulsion unit is connected in a servo loop which is completed through the positioning provided by the propulsion unit with respect to the beam being received. Amplification may be needed between the receiving transducers and their associated propulsion units. These amplifiers 51a, 52b and 53c associated with sonic receiving transducers 51, 52 and 53, respectively are preferably located within the receiving pod itself.

In operation, the sonic receiving transducers on a receiving pod porduce equal strength electrical signals when the pod is centered on the sonic beam. This is represented in FIGURE 3 by the equal lengths of the arrows located in the middle of the three sonic receiving transducers. The electrical signal is fed to the motor 61 in the associated propulsion unit which produces a proportional output rotational speed of the associated propeller thereby providing a corresponding centering thrust to the receiving pod. Since each of the electrical signals is equivalent, the thrust provided by each of the three propulsion units is equal and accordingly the receiving pod tends to stay centered on the sonic beam. The circular lines 86 shown in FIG. 3 are representations of iso-intensity lines of the sonic field in the sonic beam. It will be noted that the lines are heavier near the center of the pod. This indicates that the intensity increases toward the center and is greatest at the center of the beam.

In FIG. 4, the same iso-intensity lines 86 are depicted in a situation where the receiving pod is off-center of the sonic beam. As can be seen, sonic receiving transducer 53 of the receiving pod has been displaced toward the center of the beam and, accordingly, the arrow 83 associated with sonic receiving transducer 53 is longer than the corresponding arrow in FIG. 3. The magnitude of the intensity of the beam is much greater at this receiving transducer since the intensity is greatest at the center of the beam as previously mentioned. correspondingly, the length of the arrow in sonic receiving transducer 52 has been reduced in comparison to the corresponding arrow in FIG. 3. The same is also true of arrow 81, in comparison to the arrow in sonic receiving transducer 51. The larger electric signal produced by sonic receiving transducer 53 will correspondingly increase the speed of rotation of the propeller 62 associated with motor 61 in propulsion unit 58 (see FIG. 2) and a correspondingly greater centering thrust will be applied to the receiving pod from this unit 58 tending to center the pod on the sonic beam. Likewise the reduced electrical signals from sonic receiving transducers 51 and 52 will cause a corresponding slowing down of propellers 62 in units 56 and 57, respectively. It will be appreciated that these servo arrangements will tend to keep the receiving pod centered on the sonic beam.

Ultrasonic transmitter 27 is shown as being utilized for locating the underwater wellhead. Any of the ultrasonic transmitters could be utilized. Referring to FIG. 5, the ultrasonic transmitter 27 is energized through switch 62 which when connected to low frequency ultrasonic oscillator 63 completes the electrical path to power supply 72, thereby energizing ultrasonic transmitter 27 so that it generates a relatively low frequency ultrasonic beam which is directed vertically toward the ocean surface. The switch 62 when connected to the high frequency ultrasonic oscillator 64 energizes ultrasonic transmitter 27 as well as 28 so as to generate high frequency ultrasonic beams directed toward the ocean surface. The receiver pod 47 associated with ultrasonic transmitter 27 is capable of responding to the low frequency ultrasonic beam and is also capable of detecting the approximate center of the beam. It will be appreciated that the locating of the wellbore can also be performed by means of a separate ultrasonic transmitter for transmitting at a relatively low ultrasonic frequency located adjacent to the borehole in addition to the relatively high frequency ultrasonic transmitters. When a separate ultrasonic transmitter is utilized for generating the relatively low frequency ultrasonic beam, the receiving pods associated with the relatively high frequency ultrasonic transmitters can be utilized as the detecting means for the relatively low frequency sonic beam, or a separate receiving means can be utilized.

The relatively low frequency ultrasonic waves tend to spread into a wide angle beam in Water. Thus, this beam at the surface of the ocean has a diameter which is dependent on the dimensions of the transmitting transducer,

the transmitting frequency, and the depth at which the transmitter is located. These factors also affect the intensity of the sound wave. For example, with a l-inch diameter transducer a 100 kilocycle-per-sec-ond beam is spread over a circle on the surface of the ocean of diameter about 60 feet for a transmission originating at a 300-foot depth. Further information on the effects of frequency, depth and intensity will be provided in tables included later in the application.

In order to locate the underwater well, the drilling ship 11 must locate the float or buoy 31 which is anchored to the well head base by an anchor cable 33. However, in deep water operations the buoy is subject to considerable drift and, therefore, does not necesasrily indicate that the well head equipment is directly underneath. The electrical connection is made at the buoy 31 between the vessel and the sonic transmitters at the submarine well head. The sonic transmitter to be utilized as the relatively low ultrasonic frequency source, i.e., sonic transmitter 27, is energized by switch 62 from the surface vessel so that a relatively low frequency ultrasonic beam is generated'and directed towards the surface of the ocean. The drilling vessel 11 is maneuvered until a maximum in received intensity indicates that the center or near center of the sonic beam is detected by receiving pod 47. The sonic transmitter 27 is now switched to its high frequency mode of operation and the high frequency beam is within the receiving'range of receiving pod 47 which in conjunction with the propulsion units locks on to the beam. The sonic transmitter 28 is switched to its high frequency ultrasonic transmitting mode simultaneously with the switching of ultrasonic transmitter 27 to its high frequency ultrasonic transmitting mode. The equipment bracket 46 is rotated about the axis of the beam from transmitter 27 until receiving pod 48 senses and locks on to the generated beam from transmitter 28. At this point, the drilling ship is securely anchored and the equipment 42 carried by the bracket 46 is lowered and automatically guided along the beams toward the funnel shaped member 23 located at the submarine well head.

It has been found that for a circular piston sonic transmitter of radius R the half-apex angle A of the cone within which almost the whole of the sound of velocity V and frequency F is radiated is given by the formula:

V 7 S111 Thus with a transmitter having a radius of 5 inches in water which has a velocity of sound equal to 5 10 feet per second we have the following values for the half-apex angle A:

Frequency, cycles/sec: A

10 49.5 or .86 rad. l0 4.4 or .076 rad. 10 04 or .0076 rad. 10 004 or .00076 rad.

As previously mentioned, the attenuation of the sound Varies with the frequency, as shown by the following table in which the distances in sea water, D are given at which the intensity drops off to one tenth:

Frequency, cycles/sec: D feet 10 100,000 10 1,500 10 250 10 3.8

Accordingly, a 10-inch diameter transmitter located at a 300-foot depth gives at one megacycle per second frequency a half-apex angle of .4 which spreads the beam at the surface over a total lateral distance of only six feet and the density of sound energy at the surface is reduced both by the attenuation referred to and by geometrical spreading to .2% of all the emitted energy per square foot. At kilocycles per second frequency the half-apex angle is 4.4, and the sound energy is spread over a total lateral distance of 60 feet. The surface sound density is .02% per square foot.

Thus it can be seen that sonic apparatus is provided by means of which the submarine well may be located and equipment guided directly thereto for entry into the well. It will further be appreciated that the apparatus automatically compensates for drift caused by ocean currents since the arrangement locks onto the beams during guidance, which beams are inherently drift free.

In operation the locating of the submarine well and the guiding of equipment from a vessel on the ocean surface into the well comprises the steps of locating the buoy which is connected to the well head. As previously mentioned, the buoy is subject to drift and does not necessarily indicate the exact location of the well head. Once the buoy is located the well head equipment is electrically energized. This can be done by switching means connecting the equipment to an electrical source such as a battery. Preferably, the electrical energization is supplied by the power supply on the vessel which is electrically connected to the well head equipment by connecting means on the buoy. The electrical energization results in the generation of a relatively low frequency wide angle ultrasonic beam of energy which extends vertically from the well head equipment to the ocean surface. The low frequency ultrasonic beam of energy is received and the vessel maneuvered until substantially the center of the beam is located. The low frequency wide angle ultrasonic beam of energy is replaced by a plurality of high frequency narrow angle ultrasonic beams of energy. The equipment to be lowered from the vessel is located with respect to said high frequency narrow angle ultrasonic beams such that each beam is separately received and the equipment to be entered into the well is indexed therewith. The equipment during lowering is maneuvered so as to remain substantially fixed with respect to said high frequency ultrasonic beams thereby locating and introducing said equipment into the well.

Obviously, many modifications and variations of the invention as hereinabove set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A system for guiding equipment during lowering from the water surface so as to enter an underwater well, comprising means for generating beams of energy at the underwater well and directing said beams vertically toward the water surface, an equipment bracket adapted for lowering from said surface for carrying the equipment to be indexed with said well, a plurality of means located on said bracket each adapted for receiving one of said vertically directed beams, each beam receiving means being located laterally with respect to the equipment being carried by the bracket as a respective one of said beam generating means is located with respect to said well, each of said beam receiving means generating an electric signal indicative of the amount and direction off-center of said beam receiving means with respect to its received beam, propulsion means for centering each of said beam receiving means with respect to its received beam in accordance with said electric signal so that said equipment bracket will be guided along said beams when lowered and the equipment carried thereby will be entered into said Well.

2. Apparatus for guiding equipment from the surface of the ocean into a submarine well, comprising a plurality of ultrasonic frequency generating means for generating sonic beams, each generating means being located at a different predetermined lateral position from said well and directing said beams vertically toward the surface of the ocean, an equipment bracket attached to said equipment and adapted to be lowered from the surface of the ocean, a plurality of ultrasonic frequency receiving means located on said equipment bracket each intercepting one of said sonic beams, each of said receiving means being located at the same predetermined lateral position from said equipment carried by said bracket as One of said ultrasonic frequency generating means is located from said well, each receiving means including at least three sensing means for sensing the distance and direction off-center of said receiving means with respect to the beam generated by the corresponding laterally located beam generating means, and propulsion means for continuously correcting the position of said equipment bracket in accordance with the distance and direction off-center of each of said receiving means with respect to its intercepted beam sensed by said sensing means to maintain each of said receiving means centered on its intercepted beam, whereby the equipment bracket will be guided along said beams when lowered and the equipment carried thereby will be entered into said well.

3. Apparatus according to claim 2, wherein two ultrasonic frequency generating means are provided located on opposite sides of said well on a line which is an extension of a diameter of the submarine well, said ultrasonic frequency generating means comprising an ultrasonic frequency transmitting tranducer for each beam.

4. Apparatus according to claim 2, wherein each of said receiving means for intercepting a sonic beam is a receiving pod and each of said sensing means for sensing the distance and direction off-center of said pod with respect to said intercepted beam comprises at least three ultrasonic frequency receiving transducers arranged on and equally spaced about a circle concentric with the downwardly facing surface of said pod for sensing the intensity of sound energy received from said beam and producing a corresponding electric signal.

5. Apparatus according to claim 4, wherein said propulsion means for continuously correcting the position of said equipment bracket in accordance with the distance and direction off-center of each of said receiving means with respect to its intercepted beam comprises a plurality of propulsion units attached to each of said receiving pods, each unit being controlled by one of said ultrasonic receiving transducers and including a servo motor and a propeller driven by said servo motor to produce a thrust proportional to said electric signal tending to center said receiving p-od with respect to said beam.

6. Apparatus for guiding equipment from the surface of the ocean into a submarine well, comprising a plurality of ultrasonic frequency transmitting transducers each located at a different predetermined lateral position from said well for generating and directing sonic beams vertically toward the surface of the ocean, an equipment bracket attached to said equipment and adapted to 'be lowered from the surface of the ocean, a plurality of receiving pods located on said equipment bracket each interceptlng one of said sonic beams, each of said receiving pods being located at the same predetermined lateral position from said equipment carried by said bracket as one of said transmitting transducers is located from said well, at least three ultrasonic receiving transducers arranged on and equally spaced about a circle concentric with the downwardly facing surface of each receiving pod for detecting the intensity of sound energy received from the associated beam and producing a correspondmg electric signal, a plurality of propulsion units attached to each of said receiving pods, each propulsion unit being controlled by one of said ultrasonic frequency receiving transducers and including a servo motor and a propeller driven by said servo motor to produce a thrust propor tional to said electric signal tending to center said receiving pod with respect to said beam.

7. Apparatus according to claim 6, wherein a base member is provided having an opening therethrough communicating with said submarine well, and a funnel shaped member extending from the opening in said base member towards the ocean surface to facilitate entry of equipment attached to said equipment bracket into the submarine well.

8 Apparatus for locating a submarine well and guiding equipment from a vessel on the ocean surface into said well, comprising a plurality of ultrasonic transmitting means each located at a different predetermined lateral position with respect to said submarine well, an equipment bracket for carrying the equipment to be lowered to the submarine well and adapted to be lowered from said vessel, a plurality of ultrasonic receiving means each located on said bracket at a corresponding lateral positron with respect to said equipment carried thereby as one of said ultrasonic transmitting means is positioned with respect to said submarine well, switching means for energizing a predetermined one of said ultrasonic transmitting means to produce a relatively low frequency ultrasonic beam directed vertically toward the ocean surface, the ultrasonic receiving means located at the corresponding position with respect to the equipment carried by the bracket as said relatively low frequency ultrasonic transmitting means is positioned with respect to said submarine well providing an electric signal proportional to the sound intensity received thereby, said vessel being maneuvered until a maximum electric signal is provided, said switching means being activated to change the frequency of said predetermined one of said ultrasonic transmitting means so that said low frequency ultrasonic beam is replaced by a relatively high frequency ultrasonic beam and to simultaneously energize the other ultrasonic transmitting means to produce relatively high frequency narrow angle ultrasonic beams directed toward the ocean surface, the ultrasonic receiving means associated with said predetermined one of said ultrasonic transmitting means responding to said relatively high frequency ultrasonic beam, said bracket being rotated about the vertical axis of said ultrasonic receiving means associated with said predetermined one of said ultrasonic transmitting means until each narrow angle ultrasonic beam is received by its associated ultrasonic receiving means, each ultrasonic receiving means including at least three sensing means for sensing the distance and direction off-center of said receiving means with respect to the narrow angle beam generated by the corresponding laterally located ultrasonic transmitting means, and propulsion means for continuously correcting the position of said equipment bracket in accordance with the distance and direction off-center of each of said receiving means with respect to its intercepted narrow angle beam sensed by said sensing means to maintain each of said receiving means centered on its intercepted narrow angle beam, whereby the submarine well is located and the equipment bracket is guided along said narrow angle beams when lowered thereby introducing the equipment carried by the bracket into said well.

9. Apparatus according to claim 8, wherein each of said receiving means for intercepting an ultrasonic beam is a receiving pod and said sensing means for sensing the distance and direction ofl-center of said pod with respect to said intercepted beam comprises at least three ultrasonic frequency receiving transducers arranged on and equally spaced about a circle concentric with the downwardly facing surface of said pod for sensing the intensity of sound energy received from said beam and producing a corresponding electric signal.

10. Apparatus according to claim 9, wherein said propulsion means for continuously correcting the position of said equipment bracket in accordance with the distance and direction off-center of each of said receiving means with respect to its intercepted beam comprises a plurality of propulsion units attached to each of said receiving pods, each unit being controlled by one of said ultrasonic receiving transducers and including a servo motor and a propeller driven by said servo motor to produce a thrust proportional to said electric signal tending to center said receiving pod with respect to said beam.

11. A method for locating a submarine well and guiding equipment from a vessel on the ocean surface into the well comprising the steps of locating a buoy connected with the well head and indicating the general location of said well, electrically energizing said well head equipment and generating a relatively low frequency wide angle ultrasonic beam of energy extending from the well head to said surface, receiving said low frequency ultrasonic energy, maneuvering" said vessel until substantially the center of said beam is located, replacing said relatively low frequency wide angle ultrasonic beam of energy with a plurality of high frequency narrow an gle ultrasonic beams of energy, locating said equipment so as to receive each of said high frequency ultrasonic beams of energy and index said equipment with said well, and maneuvering said equipment so as to remain sub stantially fixed with respect to said high frequency ultrasonic beams during lowering to said well, thereby locating and introducing equipment into said well.

12. A method according to claim 11, wherein the step of locating said equipment so as to receive each of said high frequency ultrasonic beams of energy comprises locking onto one of said high frequency beams and turning said equipment about the central axis of said one high frequency beam until each of the other beams is received and said equipment is indexed with said well.

13. A method according to claim 11, wherein said step of maneuvering said equipment so as to remain substantially fixed with respect to said high frequency ultrasonic beams during lowering comprises propelling said equipment separately with respect to each high frequency ultrasonic beam in accordance with the strength of the signal received from said beam so as to compensate for any drift of the equipment with respect .to each of the respective beams.

References Cited UNITED STATES PATENTS 2,545,179 3/1951 Voorhees 3402 3,160,850 12/1964 Dudley 340-6 3,215,202 11/1965 Pollard et a1. 166.5 3,222,634 12/1965 Foster 340-3 OTHER REFERENCES Munske: Progress on Mohole, Undersea Technology, vol. 4, No. 12, December 1963, pp. 16-18 relied on.

RODNEY D. BENNETT, Primary Examiner.

CHESTER L. JUSTUS, Examiner.

R. A, FARLEY, Assistant Examiner,