JP2726570B2 - Underwater riser monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater riser for detecting the position and attitude of an underwater riser such as a flexible riser pipe used in a floating oil production facility or a riser cable used in a floating offshore structure. It concerns monitoring methods.

[0002]

2. Description of the Related Art Underwater risers such as flexible riser pipes and riser cables used in floating oil production facilities and floating offshore structures are designed to prevent breakage even when there is displacement due to floating of the floating body on the water surface. Has a floating body displacement absorbing portion formed by bending into an S-shape. When the floating body is displaced by a wave while floating on the water surface, the floating body displacement absorbing portion is deformed. Therefore, by detecting the position and posture of the underwater riser, it is determined whether or not the floating body has a displacement absorbing function. Can be monitored.

Hitherto, in order to monitor the position and attitude of such an underwater riser, a diver dive with a depth gauge to measure the depth of the water, and rises almost vertically from the depth gauge to float on the water surface. The horizontal distance from the buoy indicating the measurement position to the floating body was measured with a measuring rope or the like floating from the floating body to the buoy.

[0004]

However, in such a method in which the diver dives underwater and monitors the position and attitude of the underwater riser, the diver cannot constantly dive underwater, so that the underwater riser is constantly monitored. However, since the measurement of the horizontal distance is performed by a measuring rope that is easily swept by the tidal current, there is a disadvantage that a measurement error is large.

An object of the present invention is to provide an underwater riser monitoring method capable of avoiding the above drawbacks and constantly detecting the position and orientation of the underwater riser with high accuracy without diving.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to monitor the position and attitude of an underwater riser such as a flexible pipe or a cable rising from a water bottom to a floating body floating on the water. The position and attitude of the floating body with respect to the water bottom are measured by measuring the ultrasonic propagation time between the ultrasonic wave propagation means attached to the water bottom and the floating body and transmitting ultrasonic waves between the water bottom and the floating body. ,
Further, an ultrasonic wave propagation time is measured between ultrasonic wave propagating means which is attached to the floating body and the underwater riser and propagates ultrasonic waves between the floating body and the underwater riser. It is an object of the present invention to provide an underwater riser monitoring method, comprising detecting a position and detecting a shape of the underwater riser. The ultrasonic wave propagation means may be a combination of an ultrasonic wave transmitter and an ultrasonic wave receiver, or a combination of an ultrasonic wave transmitter / receiver and a reflector.

[0007]

[Function] Since ultrasonic waves propagate at a constant speed in water,
By transmitting ultrasonic waves between the floating body floating in the water and the underwater riser and measuring the ultrasonic propagation time, the position and orientation of the underwater riser with respect to the floating body can be detected. The position and attitude of the underwater riser with respect to the water bottom by detecting the position and attitude of the underwater riser with respect to the floating body while detecting the position and attitude of the constantly shifting floating body with respect to the water bottom, that is, the shape of the underwater riser Can be constantly monitored.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described in detail. FIG. 1 shows a state in which a method for detecting the position of an underwater riser according to the present invention is performed.
Reference numeral 0 denotes a floating body 16 from the seabed 12 so as to guide a fluid such as oil sucked from the seabed 12 through a sinker 14 fixed to the seabed (water bottom) 12 to a floating body 16 which is an offshore structure.
A flexibil pipe 10A that rises while being bent in an S-shape is shown. The flexibil pipe 10A is connected to the anchor device 1 near the sinker 14.
The distribution buoy 20 is fixed to the seabed 12 by 8, and is attached to the bow 11 a of the S-shaped part 11.

Ultrasonic waves propagate between at least three opposing positions between the seabed 12 and the floating body 16 and between the floating body 16 and the S-shaped portion 11 of the flexible pipe 10A of the underwater riser 10. First and second ultrasonic wave propagation means 22 and 24 are respectively attached. In the illustrated embodiment, three ultrasonic transmitters G1, G2,
G3 is attached, and S of flexible pipe 10A is attached.
Three ultrasonic transmitters G4, G5, G6
Are mounted, and four ultrasonic wave receivers Ra, Rb, Rc, and Rd are mounted on corner columns at the four corners of the floating body 16, respectively. The first ultrasonic wave propagation means 22
Ultrasonic transmitters G1, G2, G3 and ultrasonic receivers Ra, R
b, Rc, Rd, and the second ultrasonic wave propagation means 24 is composed of a combination of ultrasonic transmitters G4, G5, G6 and ultrasonic receivers Ra, Rb, Rc, Rd. ing.

A composite optical fiber cable 26 extends along the flexibil pipe 10A. The composite optical fiber cable 26 transmits and receives the ultrasonic transmitters G1 to G6 and the ultrasonic receivers Ra to Rd to a transmission / reception controller 28. Connected to The ultrasonic transmitters G1 to G6 are connected to the transmission / reception controller 28.
, And receives the power and transmission control signal Sd, is driven and emits ultrasonic waves, and the ultrasonic wave receivers Ra to Rd receive the ultrasonic waves and send them to the transmission / reception controller 28 as reception signals Sr which are electric signals. The transmission and reception controller 28 has a function of measuring the ultrasonic propagation time.

To implement the monitoring method of the present invention, first,
Ultrasonic waves are transmitted between the first ultrasonic wave propagation means 22, that is, from the ultrasonic wave transmitters G 1 to G 3 fixed to the sea floor 12 to the four ultrasonic wave receivers Ra to Rd mounted on the floating body 16. And these ultrasonic receivers Ra to R
d, the received signal Sr1 is supplied to the transmission / reception controller 28, and the transmission / reception controller 28 controls the transmission timing of the ultrasonic wave and the ultrasonic wave receiver Ra from the ultrasonic wave transmitters G1 to G3 according to the command of the system driver 30. The measurement of the ultrasonic propagation time t up to Rd is performed. Let the ultrasonic propagation velocity be v
_If it is set to ₀ , the distance d from the ultrasonic transmitter to the ultrasonic receiver in the system driver 30 is obtained by d = t · v ₀ . Further, the positions of the ultrasonic transmitters G1 to G3 are input to the system driver 30 as being known, and the distance between one ultrasonic receiver Ra and each of the ultrasonic transmitters G1 to G3 is determined. Once obtained, the position of the ultrasonic receiver Ra is determined. Similarly, when the positions of the ultrasonic receivers Rb to Rd are determined, the position and orientation of the floating body 16 are determined. The position and posture of the floating body 16 change every moment due to the wave of the water surface, and the position and posture that change every moment are always detected.

Next, between the second ultrasonic wave propagation means 24, that is, from the ultrasonic wave transmitters G4 to G6 mounted on the flexibil pipe 10A, the ultrasonic wave transmitter 4 is mounted on the floating body 16.
The ultrasonic wave is propagated between the two ultrasonic receivers Ra to Rd, and the reception signal Sr2 received by these ultrasonic receivers Ra to Rd is supplied to the transmission / reception controller 28. The ultrasonic propagation time from the ultrasonic transmitters G4 to G6 to the ultrasonic receivers Ra to Rd is measured. Four ultrasonic wave receivers Ra to Rd are three ultrasonic wave transmitters G4
The ultrasonic wave from G6 is received and supplied to the system driver 30 through the transmission / reception controller 28, and the three-dimensional position of the ultrasonic transmitter mounting portion of the S-shaped portion 11 of the flexibil pipe 10A is specified. Floating body 1
6 are detected, the three positions of the S-shaped portion of the flexibil pipe 10A with respect to the floating body 16 are detected, and the S-shaped portion of the flexibil pipe 10A is detected. Eleven shapes are determined. This determination result can be displayed on the CRT 32.

In the above embodiment, four ultrasonic wave receivers Ra to Rd are used for the floating body 16, but the position and posture of the floating body 16 can be detected by using three ultrasonic wave receivers. In the above embodiment, the ultrasonic transmitters G1 to G6 are attached to the seabed 12 and the flexibil pipe 10A, and the ultrasonic receivers Ra to Rd are attached to the floating body 16. An ultrasonic wave receiver may be attached, an ultrasonic transmitter may be attached to the floating body 16, or an ultrasonic transceiver may be attached to either side, and a reflector may be attached to the other side.

[0014]

According to the present invention, as described above, by utilizing the principle that ultrasonic waves propagate at a constant speed in water, ultrasonic waves are propagated between a floating body floating in water and an underwater riser. The position and attitude of the underwater riser with respect to the floating body are detected by measuring the ultrasonic propagation time of the lever. By detecting the position and posture of the underwater riser with respect to the floating body while detecting the position and posture of the underwater riser, the position and posture of the underwater riser with respect to the water bottom, that is, the shape of the underwater riser can be constantly monitored without the diver diving into the water. There are benefits.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an apparatus used in an underwater riser monitoring method according to the present invention.

FIG. 2 is a system diagram of an apparatus used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Underwater riser 10A Flexiville pipe 12 Ocean floor 16 Floating body 22 First ultrasonic wave propagation means 24 Second ultrasonic wave propagation means 28 Transmission / reception controller

Claims (1)

(57) [Claims] 1. A method for monitoring the position and posture of an underwater riser, such as a flexible pipe or a cable, which rises from a water bottom to a floating body floating on the water, and is attached to the water bottom and the floating body, respectively. Measuring the ultrasonic wave propagation time between the ultrasonic wave propagating means for transmitting ultrasonic waves between the water body and the position and the attitude of the floating body with respect to the water bottom, and the floating body attached to the floating body and the underwater riser. Measuring the ultrasonic propagation time between ultrasonic wave propagation means for transmitting ultrasonic waves between the underwater riser and the underwater riser, detecting the position of the underwater riser with respect to the floating body, and detecting the shape of the underwater riser. Underwater riser monitoring method.