Method for detecting hydrocarbon deposits
The invention relates to a method for detecting and locating hydrocarbon deposits under a body of water in several steps. First, images of a surface of the body of water taken at different times are acquired. Next, for each image, traces of hydrocarbon leaks are identified. Next, a detection map is generated. This map indicates probabilities of the presence of a hydrocarbon leak around the identified traces. The map is obtained by processing the image at least based on a criterion of distance to the identified traces. Finally, the detection maps are combined to produce a hydrocarbon leak location map.
1. A method for detecting and locating a hydrocarbon deposit under a body of water, the method comprising:
acquiring images of a surface of the body of water taken at different times;
for each image:
identifying traces of hydrocarbon leaks in the image;
generating a detection map indicative of probabilities of the presence of a hydrocarbon source around the identified traces of hydrocarbon leaks, by processing the image at least based on a criterion of distance to the identified traces of hydrocarbon leaks;
combining the detection maps generated to produce a hydrocarbon deposit leak source location map, and
wherein the processing of each image on the basis at least of a criterion of distance to the identified hydrocarbon traces comprises assigning to each point i of the image a value computed on the basis of the distance of the point i to the trace of the identified hydrocarbon leak closest to the point i, and the value assigned to a point i of the image is proportional to exp[˜min d 1 2 /(2σ 2 )], where min d i 2 denotes a minimum distance squared of the point i to a trace of a closest hydrocarbon leak, and σ 2 represents a representative variance of a zone of influence of the trace of the hydrocarbon leak.
2. The method of claim 1 , wherein the images cover an area of at least 100 km by 100 km.
3. The method according to claim 1 , wherein the hydrocarbon leak source location map is produced by combining detection maps generated from at least 50 images of the body of water.
4. The method according to claim 1 , wherein the images have a pixel representing an area greater than 25 metres by 25 metres.
5. The method according to claim 1 , wherein the images are taken at time intervals between one day and several months.
6. The method according to claim 1 , wherein the images are acquired using a device sensitive to wavelengths included in the visible and infrared range.
7. The method according to claim 1 , wherein the images are acquired using a device sensitive to wavelengths included in the radar range.
8. The method according to claim 1 , further comprising, for each image:
filtering traces of hydrocarbon leaks identified by morphological analysis to exclude traces of hydrocarbon leaks of human origin and look-alike images.
9. The method according to claim 1 , wherein images of a plurality of geographic zones are acquired to generate respective detection maps, the combination of the detection maps generated for one of the plurality of geographic zones comprising a normalisation on the basis of a number of images acquired for said geographic zone.
10. The method according to claim 1 , wherein the combination of the detection maps generated comprises, for each point i, addition of the values assigned to the point i on each detection map.