# US 2018/0321385 A1 · Systems and methods for monitoring underwater structures

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- Number: US 2018/0321385 A1
- Document ID: US20180321385A1
- Status: Published application
- Kind: A1
- Application number: 15/971,108
- Filed: 2018-05-04
- Published: 2018-11-08
- Earliest claimed: 2017-05-04
- Assignees: 3D at Depth, Inc.
- Applicants: 3D at Depth, Inc.
- Inventors: Carl W. Embry; Mark Hardy; Brett Nickerson; Neil Manning
- Web page: https://patentgrep.com/patent/US20180321385A1

## CPC

- G01S 17/89: for mapping or imaging
- G01K 13/02: for measuring temperature of moving fluids or granular materials capable of flow
- G01M 3/04: by detecting the presence of fluid at the leakage point
- G01M 3/20: using special tracer materials, e.g. dye, fluorescent material, radioactive material
- G01M 3/24: using infrasonic, sonic or ultrasonic vibrations
- G01M 3/38: by using light (G01M3/02 takes precedence)
- G01V 8/00: Prospecting or detecting by optical means
- G01V 8/10: Detecting, e.g. by using light barriers (by reflection from the object G01S17/00)
- G01K 13/026: {of moving liquids}
- G01S 17/50: Systems of measurement based on relative movement of target
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

Systems and methods for monitoring underwater structures are provided. First and second sets of point cloud data that are obtained at different times are compared to determine whether the location of the underwater structure has changed. For detecting vibration, a series of range measurements taken along a line intersecting the underwater structure are compared to one another to determine an amplitude and frequency of any vibration present in the underwater structure. For detecting temperature, the ratio of different components of return signals obtained from a point in the water surrounding the underwater structure is measured to derive the temperature of the water. Leak detection can be performed by scanning areas around the underwater structure. Monitoring systems can include a primary receiver for range measurements, and first and second temperature channel receivers for temperature measurements.

## Claims

### Claim 1

A method for monitoring an underwater structure, comprising:
taking a first three-dimensional scan of an underwater scene using a first monitoring system, wherein a first set of point cloud data is produced from the first three-dimensional scan, wherein locations of at least some points on the underwater structure are included in the first set of point cloud data;
identifying a first control point on the underwater structure to be monitored, wherein the first control point has a first three-dimensional location that corresponds to a first point included in the first set of point cloud data;
a first selected period of time after taking the first three-dimensional scan, using the first monitoring system to obtain a second three-dimensional location of the first control point on the underwater structure; and
comparing the first three-dimensional location to the second three-dimensional location to determine whether the underwater structure has moved.

### Claim 2 (depends on 1)

The method of claim 1, wherein the three-dimensional locations comprise azimuth angle, elevation angle, intensity, and range measurements.

### Claim 3 (depends on 2)

The method of claim 2, wherein making the measurements includes at least one of measuring a voltage, a time, a frequency, a phase, a number of samples, a number of digits, a pixel count, or a fringe count.

### Claim 4 (depends on 2)

The method of claim 2, wherein the measurements are made by at least one of laser scanning, ladar, flash ladar, laser triangulation, photometric stereo, stereoscopic vision, structured light, photoclinometry, stereo-photoclinometry, holographic systems, amplitude modulated continuous wave (AMCW) phase detection, chirped AMCW, amplitude frequency modulated continuous wave (FMCW) detection, true FMCW, pulse modulation codes, time of flight pulse detection.

### Claim 5 (depends on 2)

The method of claim 2, wherein the measurements are made by at least one of a scanning system device or a multi-detector device or 2-D or 3-D camera in which each detector pixel equates to an angle.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
taking a first series of range measurements from the first monitoring system along a first line corresponding to a first azimuth angle and a first elevation angle, wherein the first line intersects the underwater structure;
comparing a plurality of the range measurements within the first series of range measurements to determine whether the underwater structure is vibrating.

### Claim 7 (depends on 6)

The method of claim 6, further comprising:
determining an amplitude and a frequency of vibration of the underwater structure at the intersection of the first line and the underwater structure.

### Claim 8 (depends on 7)

The method of claim 7, further comprising:
taking a second series of range measurements from the first monitoring system along a second line corresponding to a second azimuth angle and a second elevation angle, wherein the second line is not parallel to the first line, and wherein the second line intersects the underwater structure;
determining an amplitude and a frequency of vibration to the underwater structure at the intersection of the second line and the underwater structure.

### Claim 9 (depends on 8)

The method of claim 8, further comprising:
determining a mode of vibration of the underwater structure.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
receiving a first series of return signals from a first point located in water surrounding the underwater structure, wherein the first point is located along a second azimuth angle, a second elevation angle, and at a second range relative to the first monitoring system, and wherein the first point is not located on the underwater structure;
for each of the return signals in the first series of return signals, determining a ratio of a first component of the return signal to a second component of the return signal;
determining a temperature of the water at the first point from a plurality of the determined ratios.

### Claim 11 (depends on 10)

The method of claim 10, wherein for each of the return signals in the first series of return signals the first component includes light of a first wavelength and the second component includes light of a second wavelength.

### Claim 12 (depends on 10)

The method of claim 10, wherein for each of the return signals in the first series of return signals the first component includes light of a first polarization and the second component includes light of a second polarization.

### Claim 13 (depends on 10)

The method of claim 10, wherein at least one of temperature and salinity measurements from a point sensor are used to calibrate the temperature measurement made from the plurality of the determined ratios.

### Claim 14 (depends on 13)

The method of claim 13, wherein the temperature measurement from the point sensor are compared to a temperature measurement made from a plurality of determined ratios obtained at a range gate that is closest to the point sensor and away from the range gate of the structure of interest.

### Claim 15 (depends on 10)

The method of claim 10, wherein determining a ratio of a first component of the return signal to a second component of the return signal includes providing the first component of the return signal to a first temperature channel receiver and providing the second component of the return signal to a second temperature channel receiver, the method further comprising:
for each of the return signals in the first series of return signals, providing a portion of the return signal to a primary receiver.

### Claim 16 (depends on 1)

The method of claim 1, further comprising:
determining from a plurality of series of return signals from a plurality of points located in the water surrounding the underwater structure a fluid is leaking from the underwater structure.

### Claim 17 (depends on 16)

The method of claim 16, wherein the fluid is at least one of liquid hydrocarbons, gas hydrocarbons, drilling fluid, glycol, hydraulic fluid, or other fluids used to operate and test subsea infrastructure, wherein the leak monitoring is performed during pre-commissioning pressure tests, other tests, or normal operation.

### Claim 18 (depends on 16)

The method of claim 16, wherein leak monitoring is performed for reservoir over pressure from well injection and stimulation by monitoring for seepage from methane gas bubbles and other hydrocarbons.

### Claim 19 (depends on 1)

The method of claim 1, wherein the first control point corresponds to a centroid of a feature of the underwater structure.

### Claim 20 (depends on 1)

The method of claim 1, wherein the first control point corresponds to a target placed on the underwater structure.

### Claim 21 (depends on 1)

The method of claim 1, wherein the first and second three-dimensional locations of the first control point on the underwater structure is a location of a centroid of the control point.

### Claim 22 (depends on 1)

The method of claim 1, further comprising:
identifying a second control point in the underwater scene, wherein the first three-dimensional location of the first control point has a first location relative to the second control point, wherein the second three-dimensional location of the first control point has a second location relative to the second control point; and
generating an indication that the underwater structure has moved when the first location relative to the second control point is different than the second location relative to the second control point.

### Claim 23 (depends on 22)

The method of claim 22, wherein the indicated movement includes at least one of the following:
movement and displacement of the underwater structure, including movement in X, Y, Z planes and angular tilt;
vortex induced vibration;
movement of a subsea tree;
displacement caused by water hammer events during drilling and production;
kick events caused by rapid flow rate changes or production fluids or hydrocarbons during drilling and production;
top hat structure rotational alignment changes;
subsidence relative to monuments, other structures, seabed artifacts, and vertical well or tree growth;
paddle position movement;
valve position movement; and
gauge position.

### Claim 24 (depends on 22)

The method of claim 22, wherein a volume or surface of an underwater structure is monitored over time using a plurality of series of return signals from a plurality of points located in the scene to detect change, wherein the measurements include measurements of at least one of:
anode volume for indications of corrosion; seabed volume measurement for drill cutting, scour, or subsidence; and seabed cracks or deformations due to reservoir over pressure from well injection and stimulation.

### Claim 25

A method of monitoring an underwater structure, comprising:
a light source and a receiver of a monitoring system along a first line having a first azimuth angle and a first elevation angle relative to the monitoring system, wherein the first intersects the underwater structure at least at a first point in time;
taking a first series of range measurements along the first line;
comparing a first one of the range measurements included in the first series of range measurements to a second one of the range measurements included in the first series of range measurements; and
outputting an indication of a status of the underwater structure.

### Claim 26 (depends on 25)

The method of claim 25, wherein the first series of range measurements are taken in series, the method further comprising:
deriving a first frequency of vibration from the first series of range measurements, wherein an indication that the underwater structure is vibrating is output.

### Claim 27 (depends on 25)

The method of claim 25, further comprising:
directing the light source and the receiver of the monitoring system along a second line having a second azimuth angle and a second elevation angle relative to the monitoring system;
taking a second series of range measurements along the second line;
comparing a first one of the range measurements included in the second series of range measurements to a second one of the range measurements included in the second series of range measurements;
deriving a second frequency of vibration from the second series of range measurements; and
deriving a vibration mode of the underwater structure from the first and second series of range measurements.

### Claim 28 (depends on 25)

The method of claim 25, further comprising:
directing the light source and the receiver of the monitoring system along a second line having a second azimuth angle and a second elevation angle relative to the monitoring system;
receiving a series of return signals from a point along the second line and at a selected range from the monitoring system, wherein the point is located in water surrounding the underwater structure;
determining a temperature of the water at the point;
outputting an indication of the temperature of the underwater structure.

### Claim 29

A system for detecting movement of an underwater structure, comprising:
a monitoring system, including:
a receive telescope;
a first beam splitter, wherein the first beam splitter is located along a first optical path defined by the receive telescope, and wherein the first beam splitter defines a range return signal optical path and a temperature return optical path;
a primary receiver, wherein the primary receiver is located along the range return signal optical path;
a second beam splitter, wherein the first beam splitter is located along the range return signal optical path, and wherein the second beam splitter defines a first temperature channel optical path and a second temperature channel optical path;
a first temperature channel receiver, wherein the first temperature channel receiver is located along the first temperature channel optical path;
a second temperature channel receiver, wherein the second temperature channel receiver is located along the second temperature channel optical path.

### Claim 30 (depends on 29)

The system of claim 29, further comprising:
a user interface system, including:
a user input;
a user output;
memory;
a communication interface;
a processor, wherein the user interface system processor is operable to execute application software stored in the user interface system memory to present a visualization of point cloud data obtained by the laser monitoring system through the user output, and to receive input from the user through the user input, wherein the input includes a selection of a control point;
wherein the monitoring system further includes:
a light source;
a processor;
memory;
a communication interface,
wherein the monitoring system processor is operable to execute application software stored in the monitoring system memory to operate the light source and the primary receiver to obtain three-dimensional location data, including three-dimensional location data of the underwater structure, and
wherein the monitoring system processor is operable to execute application software stored in the monitoring system memory to operate the light source and the first and second temperature channel receivers to obtain temperature data from water at a selected range from the monitoring system.