Measuring Wellhead Displacement Using Shadowgraphy

Abstract

Systems and methods for performing contactless wellhead displacement measurements include receiving a shadowgraph from an imaging sensor based on a shadow generated by a portion of a wellhead blocking light from a coherent infrared light source, the infrared light having a wavelength away from water absorption wavelengths and solar maxima wavelengths. A feature is detected in the shadowgraph based on interference patterns in the shadowgraph caused by diffraction of the light. The feature represents an edge of the portion of the wellhead. A displacement of the wellhead is measured based on the location of the feature in the shadowgraph and a previously detected location of the feature.

What is claimed is: 
     
         1 . A method for performing contactless wellhead displacement measurements, the method comprising:
 receiving a shadowgraph from an imaging sensor based on a shadow generated by a portion of a wellhead blocking light from a coherent infrared light source, the infrared light having a wavelength away from water absorption wavelengths and solar maxima wavelengths;   detecting a feature in the shadowgraph based on interference patterns in the shadowgraph caused by diffraction of the light, the feature representing an edge of the portion of the wellhead; and   measuring a displacement of the wellhead based on the location of the feature in the shadowgraph and a previously detected location of the feature.   
     
     
         2 . The method of  claim 1 , further comprising in response to determining that the displacement exceeds a threshold displacement, performing a corrective action. 
     
     
         3 . The method of  claim 2 , wherein performing the corrective action comprises generating an alert that the displacement exceeds the threshold displacement. 
     
     
         4 . The method of  claim 1 , further comprising:
 receiving a schlieren image of the portion of the wellhead from a second imaging sensor, the schlieren image generated by the light from the coherent infrared light source being focused onto a Wollaston prism; and   measuring the displacement of the wellhead using the schlieren image and a previously obtained schlieren image.   
     
     
         5 . The method of  claim 4 , wherein measuring the displacement of the wellhead using the schlieren image comprises performing a cross-correlation between the schlieren image and the previously obtained schlieren image. 
     
     
         6 . The method of  claim 4 , wherein measuring the displacement of the wellhead using the schlieren image comprises processing the schlieren image and the previously obtained schlieren image using a trained machine learning model. 
     
     
         7 . The method of  claim 4 , further comprising determining a temperature near the wellhead based on the schlieren image. 
     
     
         8 . The method of  claim 1 , further comprising iteratively measuring displacements of the portion of the wellhead at multiple instances of time to generate a time-history of the displacements. 
     
     
         9 . The method of  claim 8 , further comprising predicting anomalies of the wellhead using a machine learning model that takes as input the time-history of the displacements. 
     
     
         10 . The method of  claim 8 , further comprising determining a displacement speed of the wellhead based on the time-history of the displacements. 
     
     
         11 . The method of  claim 8 , further comprising predicting future movements of the wellhead based on a temporal gradient of the time-history of the displacements. 
     
     
         12 . A system for performing contactless wellhead displacement measurements, the system comprising:
 an illumination system positioned on a first side of a portion of a wellhead, the illumination system comprising:
 a coherent infrared light source to illuminate the portion of the wellhead, the infrared light source configured to produce light at wavelengths away from water absorption wavelengths and solar maxima wavelengths; 
   a detection system positioned on a second side of the portion of the wellhead opposite the first side, the detection system comprising:
 a beam splitter to divide incoming light into a first part and a second part; 
 optical components positioned in an optical path of the first part to focus and condition the light; 
 a first imaging sensor positioned to collect the first part of the light after propagating through the optical components; 
 a Wollaston prism positioned in an optical path of the second part; 
 a lens to collect the second part of the light and focus the light onto a second imaging sensor; and 
   a computer system configured to measure a displacement of the wellhead based on a shadowgraph generated by the first part and a schlieren image generated by the second part.   
     
     
         13 . The system of  claim 12 , wherein the coherent infrared light source comprises an infrared laser or a super luminescent diode. 
     
     
         14 . The system of  claim 13 , wherein the wavelength of the coherent infrared light source is in the range of 8 to 14 micrometers. 
     
     
         15 . The system of  claim 12 , wherein the computer system is further configured to:
 receive a shadowgraph from the first imaging sensor, the shadowgraph based on a shadow generated by a portion of the wellhead blocking light from the illumination system;   detect a feature in the shadowgraph based on interference patterns in the shadowgraph caused by diffraction of the light, the feature representing an edge of the portion of the wellhead; and   measure a displacement of the wellhead based on the location of the feature in the shadowgraph and a previously detected location of the feature.   
     
     
         16 . The system of  claim 15 , wherein the computer system is further configured to:
 receive a schlieren image of the portion of the wellhead from the second imaging sensor, the schlieren image generated by the light from the coherent infrared light source being focused onto the Wollaston prism; and   measure the displacement of the wellhead using the schlieren image and a previously obtained schlieren image.   
     
     
         17 . The system of  claim 16 , wherein measuring the displacement of the wellhead using the schlieren image comprises performing a cross-correlation between the schlieren image and the previously obtained schlieren image. 
     
     
         18 . The system of  claim 16 , wherein measuring the displacement of the wellhead using the schlieren image comprises processing the schlieren image and the previously obtained schlieren image using a trained machine learning model. 
     
     
         19 . The system of  claim 16 , wherein the computers system is further configured to determine a temperature near the wellhead based on the schlieren image. 
     
     
         20 . The system of  claim 15 , wherein the computer system is further configured to iteratively measure displacements of the portion of the wellhead at multiple instances of time to generate a time-history of the displacements.