Patent ID: 11920441
Assignee: MAGNETIC VARIATION SERVICES, LLC
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 14:
15. A computer system comprising:
a processor;
a memory coupled to the processor, the memory containing instructions executable by the processor for performing some or all of the following steps:
taking a plurality of measurements at a plurality of measured depths, MDsw along a borehole of a subject well being drilled;
selecting a plurality of offset well logs with measurements at a plurality of stratigraphic vertical depths, SVDow, each having a plurality of measurements at true vertical depths, TVDow;
computing a misfit value, MV for each of a plurality of pairs of measurements of the subject well at the measured depths, MDsw and the offset well stratigraphic vertical depths, SVDow, wherein the misfit value, MV is computed using the plurality of offset well logs;

generating a mapping of true vertical depths, TVDow against stratigraphic vertical depth, SVDow, wherein the mapping relates a stratigraphic vertical depth, SVDow to the corresponding true vertical depths, TVDow of the plurality of the offset well logs;
computing a combined Misfit value, MVc for each of the measurements at the subject well measured depths, MDsw and offset measurements of true vertical depths, TVDow;
determining, responsive to the computed misfit value, MV and the combined misfit value, MVc, a stratigraphic vertical depth of the borehole of the subject well, SVDsw, wherein the stratigraphic vertical depth, SVDsw is determined to correspond to a minimum cost related to the combined misfit value, MVc; and
sending one or more control signals to one or more control systems of a drilling rig drilling the subject well to drill the borehole of the subject well responsive to the determined stratigraphic vertical depth, SVDsw to a target stratigraphic depth, TSVDsw.