Patent ID: 6999878

Claim:
A method of locating a position of an interface ( 5 ) between a first fluid (f 1 ) and a second fluid (f 2 ) in a reservoir ( 4 ), the method comprising: a°) initiating a reference transient flow condition to produce a reference pressure difference (ΔP ref (t)) in the reservoir ( 4 ), b°) initiating an effective transient flow condition to produce an effective pressure difference (ΔP u1 (t)) in the reservoir ( 4 ) c°) comparing the pressure differences (ΔP ref (t), ΔP u1 (t)) as a function of time, d°) determining a point in time (δ 1 ) when a pressure wave, generated by said effective transient flow, substantially arrives at the interface ( 5 ); and e) determining the position of the interface ( 5 ) based on the time (δ 1 ).