Method and device for depth positioning downhole tool and associated measurement log of a hydrocarbon well

A method of determining a velocity of a production logging tool deployed and run through a hydrocarbon well in production along a depth portion of the hydrocarbon well, the production logging tool comprising at least two passive magnetic sensors, said velocity determination method comprises:

• generating a set of magnetic measurements of a depth portion of the hydrocarbon well from a first passive magnetic sensor along the depth portion of the hydrocarbon well, the set of magnetic measurements comprising magnitude and/or direction measurements of the magnetic field that forms a characteristic magnetic field pattern representative of a surrounding magnetic environment of the hydrocarbon well all along the depth portion;
• comparing said set of magnetic measurements to another set of magnetic measurements, the other set of magnetic measurements being a reference set of magnetic measurements generated either by a second passive magnetic sensor spaced from the first passive magnetic sensor from a defined distance deployed and run in the hydrocarbon well simultaneously;
• determining the maximum of correlation between the set of magnetic measurements and the reference set of magnetic measurements, said maximum being related to identifiable characteristic magnetic field pattern over a part of the depth portion;
• determining a time of flight between the two sets of magnetic measurements by determining the maximum of correlation in a sliding time window;
• and
• calculating a velocity of the first passive magnetic sensor along the depth portion of the hydrocarbon well.

A method of determining a density of wellbore fluid flowing into a depth portion of a hydrocarbon well in production by correcting a depth positioning scale of a pressure gradient measurements log obtained from a pressure sensor by firstly, implementing a depth positioning method comprising:

• generating a set of magnetic measurements of a depth portion of the hydrocarbon well from a first passive magnetic sensor along the depth portion of the hydrocarbon well, the set of magnetic measurements comprising magnitude and/or direction measurements of the magnetic field that forms a characteristic magnetic field pattern representative of a surrounding magnetic environment of the hydrocarbon well all along the depth portion;
• comparing said set of magnetic measurements to another set of magnetic measurements, the other set of magnetic measurements being a reference set of magnetic measurements generated either by a same or similar passive magnetic sensor deployed and run in the hydrocarbon well earlier, or by a second passive magnetic sensor spaced from the first passive magnetic sensor from a defined distance deployed and run in the hydrocarbon well simultaneously;
• and
• determining the maximum of correlation between the set of magnetic measurements and the reference set of magnetic measurements, said maximum being related to identifiable characteristic magnetic field pattern over a part of the depth portion;
• and
• secondly, calculating the density by dividing the pressure gradient by earth gravity, eventually corrected by the cosine of an hydrocarbon well inclination in case of deviated hydrocarbon well.

A method of evaluating hydrocarbon well integrity by comparing a reference set of magnetic measurements taken at an earlier time corresponding to an undamaged well casing, to a subsequent set of magnetic measurements showing magnetic anomalies corresponding to a damaged well casing and relating said anomalies to damaged well casing portions depths by implementing a depth positioning method comprising:

• generating a set of magnetic measurements of a depth portion of the hydrocarbon well from a first passive magnetic sensor along the depth portion of the hydrocarbon well, the set of magnetic measurements comprising magnitude and/or direction measurements of the magnetic field that forms a characteristic magnetic field pattern representative of a surrounding magnetic environment of the hydrocarbon well all along the depth portion;
• comparing said set of magnetic measurements to another set of magnetic measurements, the other set of magnetic measurements being the reference set of magnetic measurements generated either by a same or similar passive magnetic sensor deployed and run in the hydrocarbon well earlier, or by a second passive magnetic sensor spaced from the first passive magnetic sensor from a defined distance deployed and run in the hydrocarbon well simultaneously;
• and
• determining the maximum of correlation between the set of magnetic measurements and the reference set of magnetic measurements, said maximum being related to identifiable characteristic magnetic field pattern over a part of the depth portion.

A depth positioning device to position a production logging tool and a measurement log in a hydrocarbon well in production obtained by means of said tool, the depth positioning device comprises:

• a first passive magnetic sensor arranged to generate a set of magnetic measurements of a depth portion of the hydrocarbon well, the set of magnetic measurements comprising multiple magnitude and/or direction measurements of the magnetic field that forms a characteristic magnetic field pattern representative of a surrounding magnetic environment of the hydrocarbon well all along the depth portion;
• means for deploying and running the first passive magnetic sensor along the depth portion of the hydrocarbon well;
• and
• a processing unit:
• arranged to compare said set of magnetic measurements to another set of magnetic measurements, the other set of magnetic measurements being a reference set of magnetic measurements generated either by a same or similar passive magnetic sensor deployed and run in the hydrocarbon well earlier, or by a second passive magnetic sensor spaced from the first passive magnetic sensor from a defined distance so as to be deployed and run in the hydrocarbon well simultaneously, and
• arranged to determine the maximum of correlation between the set of magnetic measurements and the reference set of magnetic measurements, said maximum being related to identifiable characteristic magnetic field pattern over a part of the depth portion.

A production logging tool comprising a depth positioning device to position a production logging tool and a measurement log in a hydrocarbon well in production obtained by means of said tool, the depth positioning device comprises:

• a first passive magnetic sensor arranged to generate a set of magnetic measurements of a depth portion of the hydrocarbon well, the set of magnetic measurements comprising multiple magnitude and/or direction measurements of the magnetic field that forms a characteristic magnetic field pattern representative of a surrounding magnetic environment of the hydrocarbon well all along the depth portion;
• means for deploying and running the first passive magnetic sensor along the depth portion of the hydrocarbon well;
• a processing unit:
• arranged to compare said set of magnetic measurements to another set of magnetic measurements, the other set of magnetic measurements being a reference set of magnetic measurements generated either by a same or similar passive magnetic sensor deployed and run in the hydrocarbon well earlier, or by a second passive magnetic sensor spaced from the first passive magnetic sensor from a defined distance so as to be deployed and run in the hydrocarbon well simultaneously;
• and
• arranged to determine the maximum of correlation between the set of magnetic measurements and the reference set of magnetic measurements, said maximum being related to identifiable characteristic magnetic field pattern over a part of the depth portion;
• and
• at least one sensor responsive to at least one property of a multiphase flow mixture flowing in the hydrocarbon well or at least one property of a formation surrounding the hydrocarbon well.

A recording ball comprising a protective shell of spherical form having an average density such that it can be swept along the hydrocarbon well with a multiphase flow mixture flowing in the hydrocarbon well, a battery, an electronic board connected to at least one sensor responsive to at least one property of the multiphase flow mixture or at least one property of a formation surrounding the hydrocarbon well and to a depth positioning device comprising:

• a first passive magnetic sensor arranged to generate a set of magnetic measurements of a depth portion of the hydrocarbon well, the set of magnetic measurements comprising multiple magnitude and/or direction measurements of the magnetic field that forms a characteristic magnetic field pattern representative of a surrounding magnetic environment of the hydrocarbon well all along the depth portion;
• means for deploying and running the first passive magnetic sensor along the depth portion of the hydrocarbon well;
• and
• a processing unit:
• arranged to compare said set of magnetic measurements to another set of magnetic measurements, the other set of magnetic measurements being a reference set of magnetic measurements generated either by a same or similar passive magnetic sensor deployed and run in the hydrocarbon well earlier, or by a second passive magnetic sensor spaced from the first passive magnetic sensor from a defined distance so as to be deployed and run in the hydrocarbon well simultaneously;
• and
• arranged to determine the maximum of correlation between the set of magnetic measurements and the reference set of magnetic measurements, said maximum being related to identifiable characteristic magnetic field pattern over a part of the depth portion.