US3227874A

US3227874A - Method for viewing objects in a lightscattering atmosphere

Info

Publication number: US3227874A
Application number: US264963A
Authority: US
Inventors: Jr Noyes D Smith
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1963-03-13
Filing date: 1963-03-13
Publication date: 1966-01-04
Anticipated expiration: 1983-01-04

Description

Jan. 4, 1966 N. D. SMITH, JR

METHOD FOR VIEWING OBJECTS IN A LIGHT-SCATTERING ATMOSPHERE Filed March 15, 1963 INVENTOR:

NOYES D. SMITH, JR. BY: WW 2%? HIS ATTORNEY United States Patent 3,227,874 METHOD FOR VIEWING OBJECTS IN A LIGHT- SCATTERING ATM'QSPHERE Noyes D. Smith, In, Bellaire, Tex., assignor to Shell Oil C0mpany, New York, N.Y., a corporation of Delaware Filed Mar. 13, 1963, Ser. No. 264,963 4 Claims. (Cl. 25071) This invention relates to a method of improving the clarity with which objects can be viewed by a camera surrounded by an atmosphere that tends to scatter light. More specifically this invention deals with a method of observing objects submerged in water by means of a television or photographic camera.

One of the most important uses of this invention is in the observation of equipment of underwater wells which are drilled, for example, in the ocean floor for the production of oil and gas.

At the present time, wells are being drilled in the ocean floor at depths of 400 feet and wells at depths of 1000 feet or more are contemplated in the near future. When Working at these depths it becomes necessary to maintain a great deal of equipment beneath the surface of the water. Many times during the drilling or working on underwater Well, the drilling or other equipment must be temporarily withdrawn from the well, e.g., to replace a drilling bit, etc., and subsequently later replaced. Due to the great depth, the problem of alignment of the drilling platform above the water with the Well is increased. In the event that there should be a malfunction of the well equipment or a serious misalignment problem, some means must be provided for observing the submerged equipment to determine the cause of the trouble or else the equipment must be raised to the surface, resulting in a great loss of time and money. Furthermore, with the advent of underwater completion techniques, many operations, such as bolting various components together, must be manually performed on equipment which is at all times underwater. In the past these functions have been performed by a diver. As the depth of the water in which the wells are drilled becomes deeper, the proportion of the time that the diver can devote to useful work decreases, resulting in further loss of time and money. Although systems have been devised for performing these manual operations automatically from the surface, some means must still be provided to observe the underwater equipment.

It has therefore become common practice when working on underwater wells to use a television or photographic camera for observation purposes wherever possible. The television or photographic camera is lowered into the water along with suitable lamps capable of emitting a visible spectrum for illuminating the area of interest, so that the operators at the surface may observe the equipment beneath the surface of the water. The use of light in the visible spectrum for underwater television or photography, however, has the disadvantage that the resulting icture has very poor contrast. This is caused by the scattering of the visible light rays both by the water and by material, such as dirt particles, which is suspended in the water.

To reduce the scattering of the illuminating light and thereby improve the clarity of the picture, it appears that light of a longer wave length than the visible light spectrum, i.e., infrared light, should be used as the illuminating source. Although it is true that using an illuminating source of infrared light will reduce the scattering of the light due to the water, the material suspended in the water will still reflect a great deal of the illuminating light back to the camera. This reflected light will cause the resulting picture to still have poor contrast.

It is therefore an object of this invention to provide an improved method of observing underwater equipment.

It is a further object of this invention to provide a method of improving the contrast of the images presented to a camera surrounded by a medium which scatters visible light.

Briefly, the above objects are achieved by coating the submerged object to be viewed with a material that fluoresces and may also phosphoresce in the red and/or infrared region of the spectrum (Wave length greater than 6100 A.) in response to light of a predetermined frequency; illuminating the object to be viewed with light free from red and infrared frequencies and which causes said fluorescence; and then filtering the light transmitted to the camera with a filter passing only red and/ or infrared light. The fluorescent materials are sometimes called phosphors or prosphorescent substances.

These and other objects of the present invention will be understood from the following description taken with reference to the attached drawings wherein:

FIGURE 1 is an isometric view of one form of the underwater apparatus which can be used to carry out applicants invention; and

FIGURE 2 is a cross-sectional on a reduced scale showing the surface apparatus used with the underwater apparatus of FIGURE 1; and

FIGURE 3 is a cross-sectional elevation view of the apparatus necessary to practice applicants invention.

Referring to FIGURES 1 and 2 of the drawings, a drilling barge 11 of any suitable fixed or floatable type is illustrated as floating on the surface of a body of water 12 and substantially fixedly positioned over a preselected location of the ocean floor 13 by anchor lines 14 and 15 running to anchors (not shown) sunk in or on the ocean floor. Equipment of this type may be used when carrying out well drilling, well completion, or well maintenance operations in water varying from about to 1500 feet or more in depth. The drilling barge is equipped with a suitable derrick 16 containing fall lines 17 and a hoist (not shown), as well as other auxiliary equipment needed during the drilling or servicing of a well. Thus, in this instance the drilling rig is shown as being provided with a traveling block 21 to which is secured a pair of elevators or other suitable means for connecting to the top of a string of pipe 23, commonly known as a running pipe string or running string, by which equipment may be lowered down to or into a well.

The derrick 16 is positioned over a drilling slot or well 26 which extends vertically through the barge 11 in a conventional manner. When using the equipment of the present invention, the slot 26 and the barge 11 may be either centrally located or extend in from one edge. However, operations with the apparatus of the present invention may be carried out over the side of the barge without the use of the slot.

An underwater wellhead support base, which is represented by a horizontally-extending support base or other frame '27, which may have a casinghead 28 secured thereto and centrally positioned thereon, is preferably anchored to the ocean floor by means of a conductor pipe or surface casing (not shown) which is attached to the support base 27 and installed and preferably cemented in the ocean floor. Secured to the wellhead support base 27 are two or

more guide columns

32 and 33 having

guide cables

34 and 35 extending vertically therefrom to the drilling barge 11 where they are preferably secured to the barge by means of constant-

tension winches

36 and 37. The

guide cables

34 and 35 are provided for the purpose of guiding pieces of equipment into alignment on or in the casinghead 28 positioned at the ocean floor.

In FIGURES 1 and 2, a well connector 40 is shown 3 connected to the casinghead 28 and to the surface by means of a running pipe string 23 which extends to the barge 11 and is suspended from the derrick 16. Extending outwardly from the connector device 40 are pairs of

guide arms

43 and 44 having the outer ends thereof slidably mounted on the

guide lines

34 and 35, respectively. The guide system just briefly described is shown in greater detail in the copending application of Lloyd G. Otteman and John A. Haeber, Ser. No. 102,222, filed Apr. 11, 1961, now Patent No. 3,143,171, issued Aug. 4, 1964.

In order to observe the well connector 40 once it is below the surface of the water, a television camera 50 and suitable illuminating means 51, which according to the invention emit light in the ultraviolet spectrum, are lowered from the barge 11. The camera 50 and illuminating means 51 are mounted on a carriage 52 which is suspended from the barge 11 by means of a multi-conductor cable 53 which is also used to supply power to the camera 50 and illuminating means 51 and to transmit the television signals to the surface. A second set of

guide cables

54, 55 anchored in

guide columns

56, 57 and secured to the barge by means of constant-

tension winches

58, 59 are provided to guide the carriage as it is lowered. Such a carriage and guide system are de scribed in the copending application of K. W. Foster and R. L. Geer, Ser. No. 250,604, filed Jan. 10, 1963, now Patent No. 3,184,541, issued May 18, 1965.

Referring now to FIGURE 3, there is shown a portion of the object to be viewed, i.e., the well connector 40, which according to the invention has on its surface a coating 61 which will fluoresce or phosphoresce in the infrared and/or red region of the light spectrum when irradiated with light of a predetermined frequency, which is preferably in the ultraviolet region of light spectrum. Such a coating may consist, for example, of a paint or lacquer which is transparent to ultraviolet light and contains a substance which phosphoresces in the red or infrared region of the light spectrum when irradiated with ultraviolet light. Examples of such a substance would be rhombohedral Al O :Cr and hexagonal ZnS.CdS:Cu- (0.005). The crystals of the former mentioned substance, in response to ultraviolet light excitation, emit a spectrum having its two most intense lines at 6927 and 6947 angstroms which are at the limit of the red region of the light spectrum, while those of the latter emit a spectrum which has its maximum intensity a. little above 7100 A. which is within the infrared region of the light spectrum. Other examples of materials that possess this phenomenon can be found in the book Luminescene of Solids, by H. W. Leverenz, Wiley and Sons, 1950.

The illuminating means 51, which in the given example may be any suitable source of ultraviolet light, preferably consists of a quartz mercury arc lamp 62 mounted in a water tight casing 63. A filter 64 which passes only the ultraviolet spectrum is placed in the path of light from the lamp 62. The ultraviolet light, after passing through the filter 64 and if necessary a lens 65, is focused on the portion of the underwater equipment to be viewed which causes the aforementioned coating to give ofl light in the red and/or infrared region of the light spectrum.

The radiations produced by the coating 61 are transmitted to the television camera 50 through a lens 66 and a filter 67 mounted across the face of the camera 50. The filter 67 is selected to pass only red and infrared light. The red and infrared light, because it has a longer wave length than visible light, will tend to be less scattered by the surrounding water than the visible light and will thus result in a clearer picture of the viewed object.

While the invention has been described for an underwater television system, it is understood that a photographic camera may equally well be used in place of the television camera. It is also to be understood that the invention is not limited to underwater use but may be used in any light scattering medium.

I claim as my invention:

1. For use in underwater operations wherein an underwater installation is positioned at or near the ocean floor in a body of water having suspended therein light-scattering and reflecting particles in an amount sufficient to substantially reduce observations made on said installation, the method of improving the clarity with which the installation may be observed by means of an underwater camera comprising:

(a) providing a coating on a portion of the installation to be observed, said coating including a substance which fluoresces at a wave length greater than 6100 A. in response to light excitation; V

(b) transmitting light having a wave length shorter than 6100 A. through said body of water to illuminate the portion of the installation to be observed and cause said fluorescence;

(c) observing the coated portion of said installation by means of said underwater camera; and

(d) filtering the light admitted to said camera to pass only light of a wave length greater than 6100 A., whereby the illuminating light which is scattered and/ or reflected back to the camera by the particles in the water is prevented from entering the camera.

2. A method for use in underwater operations wherein an underwater installation is positioned at or near the ocean floor in a body of water having suspended therein light-scattering and reflecting particles in an amount sufficient to substantially reduce observations made on said installation, said method comprising:

(a) providing a coating on portions of the installation to be observed, said coating including a material which fluoresces at a wave length greater than 6100 A. when excited by ultraviolet light;

(b) transmitting ultraviolet light through said body of water to illuminate said coated portions of said installation and excite said material;

(c) observing said coated portions of said installation with an underwater camera; and

(d) filtering the light admitted to said camera to pass only light of a wave length greater than 6100 A., whereby the illuminating light which is scattered and/ or reflected back to said camera by said particles is prevented from entering the camera, and thereby causing the clarity of the resulting picture to be improved.

3. A method for use in underwater operations wherein an underwater installation is positioned at or near the ocean floor in a body of water having light-scattering and reflecting particles suspended therein in an amount sufficient to substantially reduce observations made on said installation, said method comprising:

(a) providing at least a portion of said installation with a coating including a lacquer which is transparent to ultraviolet light and contains minerals which fluoresce at a wave length greater than 6100 A. when excited by ultraviolet light;

(b) transmitting ultraviolet light through said body of water to illuminate a coated portion of said installation and thereby cause said minerals to fluoresce;

(c) observing the illuminated portion of the installation by means of an underwater camera; and

(d) filtering the light admitted to said camera to remove the light of higher frequency than that of red light, whereby the illuminating light, which is scattered and/or reflected back to the camera by said particles, is prevented from entering the camera.

4. A method for use in underwater operations wherein an underwater installation is positioned at or near the ocean floor in a body of water having suspended therein light-scattering and reflecting particles in an amount sufficient to substantially reduce observations made on said installation, said method comprising:

(a) coating the portions of said installation to be observed with a lacquer which is transparent to ultraviolet light and contains minerals which fluoresce in the infrared region of the spectrum when excited by ultraviolet light;

(b) submerging and positioning said installation at a desired location in said body of water;

(c) transmitting ultraviolet light through said body of water to illuminate a coated portion of said installation, thereby causing said minerals to fluoresce;

(d) observing the illuminated portion of said installation by means of an underwater camera; and

(e) filtering the light admitted to said camera to remove the light of higher frequency than that of infrared light, whereby the illuminating light, which 15 has been scattered and/ or reflected back to the camera by the particles suspended in said body of water, is prevented from entering the camera.

References Cited by the Examiner UNITED STATES PATENTS Claudet 250-71 Garrison 25071 Urbach 25071 Urbach 25071 Reistle 175-7 Hayes 1757 Johnson 16666.5

Burkhardt 250 83.3

RALPH G. NILSON, Primary Examiner.

J. W. LAWRENCE, Examiner.

Claims

1. FOR USE IN UNDERWATER OPERATIONS WHEREIN AN UNDERWATER INSTALLATION IS POSITIONED AT OR NEAR THE OCEAN FLOOR IN A BODY OF WATER HAVING SUSPENDED THEREIN LIGHT-SCATTER ING AND REFLECTING PARTICLES IN AN AMOUNT SUFFICIENT TO SUBSTANTIALLY REDUCE OBSERVATIONS MADE ON SAID INSTALLATION, THE METHOD OF IMPROVING THE CLARITY WITH WHICH THE INSTALLATION MAY BE OBSERVED BY MEANS OF AN UNDERWATER CAMERA COMPRISING: (A) PROVIDING A COATING ON A PORTION OF THE INSTALLATION TO BE OBSERVED, SAID COATING INCLUDING A SUBSTANCE WHICH FLUORESCES AT A WAVE LENGTH GREATER THAN 6100 A. IN RESPONSE TO LIGHT EXCITATION; (B) TRANSMITTING LIGHT HAVING A WAVE LENGTH SHORTER THAN 6100 A. THROUGH SAID BODY OF WATER TO ILLUMINATE THE PORTION OF THE INSTALLATION TO BE OBSERVED AND CAUSE SAID FLUORESCENCE; (C) OBSERVING THE COATED PORTION OF SAID INSTALLATION BY MEANS OF SAID UNDERWATER CAMERA; AND (D) FILTERING THE LIGHT ADMITTED TO SAID CAMERA TO PASS ONLY LIGHT OF A WAVE LENGTH GREATER THAN 6100 A., WHEREBY THE ILLUMINATING LIGHT WHICH IS SCATTERED AND/OR REFLECTED BACK TO THE CAMERA BY THE PARTICLES IN THE WATER IS PREVENTED FROM ENTERING THE CAMERA.