Patent ID: 8457896

Claim:
A method of determining at least one location of at least one wellbore casing within a wellbore conductor, the method comprising: providing sensor measurements generated by at least one sensor within the wellbore conductor, the sensor measurements indicative of at least one location of the at least one wellbore casing within the wellbore conductor as a function of position along the wellbore conductor; and calculating, using a processor, the at least one location of the at least one wellbore casing using the sensor measurements and at least one geometric constraint, the at least one geometric constraint originating at least in part from at least one physical parameter of the wellbore conductor, or at least one physical parameter of the at least one wellbore casing, or both, wherein the at least one wellbore casing comprises a first wellbore casing and a second wellbore casing, wherein calculating the at least one location of the at least one wellbore casing comprises: estimating, based at least in part on the at least one geometric constraint and the sensor measurements, a position along the wellbore conductor at which the first and second wellbore casings touch one another; and using the estimated position to calculate locations of the first and second wellbore casings, wherein estimating the position comprises: using the sensor measurements to calculate an initial value of a quantity t representing the position; calculating an initial value of a proportionality factor K; and using a mapping to at least approximate the distance between the first and second wellbore casings as a function of position along the wellbore conductor, the mapping at least in part defined by an expression dependent at least in part on the quantity t, the proportionality factor K, and the at least one geometric constraint.