Patent ID: 8517096

Claim:
A method for evaluating the loss circulation in a wellbore made of a casing and an annular with an annular fluid within, comprising: (i) fixing a reel of wound optic fiber line on an objet, said object defining a plug in said casing; (ii) fixing the optic line on a first position to a reference point; (iii) moving the object within the casing so that the optic fiber line is unwound from the reel on a second position; (iv) generating from the first position a signal along the optic fiber line; (v) measuring from the first position a change of said signal along the optic fiber line, said signal informing on the second position; (vi) deducing from said change of said signal a displacement of the object and a flow rate at an object level Q s ; (vii) measuring the flow rate of the fluid exiting the annular at the surface level Q r ; (viii) evaluating the loss circulation Q l by comparing the flow rate at the object level Q s with the flow rate at the surface level Q r .