Borehole correction for resistivity LWD tools with ultrasonic log while drilling caliper

A system comprising:

• one or more processors;
• and
• at least one computer-readable storage medium having stored therein instructions which, when executed by the one or more processors, cause the one or more processors to:
• access resistivity measurement data gathered by one or more resistivity sensors of a log while drilling (“LWD”) tool during operation of the LWD tool in a borehole;
• identify an apparent resistivity associated with a formation surrounding the borehole from the resistivity measurement data;
• select a model from a plurality of models based on ultrasonic caliper measurement data, wherein the plurality of models specify relationships between an apparent resistivity variable and a borehole correction factor variable;
• apply the model to the apparent resistivity to identify a borehole correction factor based on the ratio between the apparent resistivity and a true resistivity;
• determine the true resistivity of the formation by applying the borehole correction factor to the apparent resistivity;
• and
• geosteer the LWD tool based on the determined true resistivity of the formation by rotating a drill bit through a subterranean formation.

A non-transitory computer-readable medium having instructions stored thereon that, when executed by at least one processor, cause the at least one processor to perform operations comprising:

• accessing resistivity measurement data gathered by one or more resistivity sensors of a log while drilling (“LWD”) tool during operation of the LWD tool in a borehole;
• identifying an apparent resistivity associated with a formation surrounding the borehole from the resistivity measurement data;
• selecting a model from a plurality of models based on ultrasonic caliper measurement data, wherein the plurality of models specify relationships between an apparent resistivity variable and a borehole correction factor variable;
• applying the model to the apparent resistivity to identify a borehole correction factor based on the ratio between the apparent resistivity and a true resistivity;
• determining the true resistivity of the formation by applying the borehole correction factor to the apparent resistivity;
• and
• geosteering the LWD tool based on the determined true resistivity of the formation by rotating a drill bit through a subterranean formation.