Patent ID: 6016461
Filing Date: 2000-01-18
Classification: G01V

Abstract:
A method for producing maps of the risks in positioning a well in an environment, in which use is made of a first interpreted horizon (H.sub.0) extracted from a seismic block migrated with at least a first value of a velocity (V) known with an uncertainty (.DELTA.V), which consists in performing the following steps: a) making a second interpreted horizon (H.sub.1) by migration of the first horizon (H.sub.0) using a second value (V+.DELTA.V) of the velocity, equal to the first value (V) plus the uncertainty (.DELTA.V);b) making a third interpreted horizon (H.sub.2) by migration of the first horizon (H.sub.0) using a third value (V-.DELTA.V) of the velocity, equal to the first value (V) less the uncertainty (.DELTA.V);c) selecting a positioning point (X.sub.0) for the well on the said first horizon (H.sub.0) and plotting a vertical (D) which passes through the said point (X.sub.0) and intersects the second and third horizons(H.sub.1 and H.sub.2) at migrated points (X.sub.1, X.sub.2);d) on the said first interpreted horizon (H.sub.0), determining the positions (A, B) corresponding to the said migrated points (X.sub.1, X.sub.2), the portion of the first interpreted horizon (H.sub.0) located between the said positions (A, B) constituting the locus of the potential positions of the well for the said uncertainty (.DELTA.V).