Method and apparatus for measurement-while-drilling utilizing improved antennas

An antenna assembly for use in a wellbore for communicating electromagnetic energy, comprising:

• an elongated member;
• an antenna pathway defined in said elongated member;
• an antenna member at least partially disposed in said antenna pathway with portions of said antenna member defining a plurality of discrete communication regions to facilitate communication of said electromagnetic energy;
• and
• a plurality of electrically-operable magnetic circuit elements, communicating with particular ones of said plurality of discrete communication regions of said antenna member, for altering antenna gain in response to at least one control signal.

An antenna assembly, for use in a drillstring in a measurement-while-drilling system, during drilling operations to interrogate a borehole and surrounding formation, utilizing electromagnetic energy comprising:

• a tubular member for coupling in a selected position within said drillstring during drilling operations, said tubular member including (a) an inner peripheral surface defining a central bore (b) an outer peripheral surface, and (c) a tubular body defined therebetween;
• an antenna pathway defined in said tubular body of said tubular member;
• an antenna member at least partially disposed in said antenna pathway;
• wherein said tubular member includes a contoured portion which defines a plurality of interleaved groove regions having a reduced radial dimension and land regions formed in said tubular body;
• and
• wherein said antenna pathway traverses said plurality of interleaved groove regions and land regions of said contoured portion;
• and
• wherein said antenna member extends out of said tubular body of said tubular member at each of said plurality of groove regions to facilitate communication of said electromagnetic energy between said antenna member and said borehole and surrounding formation and passes into said plurality of land regions.

An improved antenna member for use in a measurement-while-drilling system, during drilling operations in a wellbore, comprising:

• a tubular member for coupling in a selected location within a drillstring;
• a plurality of axial grooves (1) cut into said tubular member at particular azimuthal locations and (2) defining a plurality of land regions therebetween;
• a circular antenna conduit (1) substantially concentric with a central longitudinal axis of said tubular member, (2) extending through each of said plurality of land regions, and (3) communicating with each of said plurality of axial grooves;
• and
• an antenna winding extending through said circular antenna conduit for transmitting or receiving electromagnetic radiation at portions of said antenna winding located in said plurality of axial grooves.

A measurement-while-drilling apparatus for use during drilling operations to interrogate a borehole and surrounding formation, comprising;

• a transmitting member including at least one transmitting antenna for receiving an energizing electrical current and for selectively generating an interrogating electromagnetic signal for propagation through said borehole and surrounding formation;
• a receiving member, spaced apart from said transmitting member, and including at least one receiving antenna for detecting an interrogating electromagnetic signal and generating an electrical current representative thereof;
• a signal processing member for identifying at least one characteristic of said interrogating electromagnetic signal which is representative of at least one property of at least one of (1) said borehole, and (2) said surrounding formation;
• a tubular member of coupling in a selected position within said drillstring and for supporting said transmitting member, said receiving member, and said signal processing member;
• an antenna assembly, for use in at least one (a) said transmitting member, and (b) said receiving member, including:
• (1) an antenna pathway, with a plurality of enclosed pathway portions surrounded by said tubular member, and a plurality of open pathway portions with said tubular member only partially surrounding each of said plurality of open pathway portions;
• (2) an antenna member disposed in said antenna pathway;
• (3) wherein said electromagnetic energy is preferentially communicated between said antenna member and said borehole and surrounding formation at said plurality of open pathway portions in comparison with said plurality of enclosed pathway portions.

A measurement-while-drilling apparatus for use during drilling operations to interrogate a borehole comprising:

• a transmitting member including at least one transmitting antenna for receiving an energizing electrical current and for selectively generating an interrogating electromagnetic signal for propagation through said borehole and surrounding formation;
• a receiving member, spaced apart from transmitting member, including at least one receiving antenna for detecting said interrogating electromagnetic signal and generating an electrical current representative thereof;
• a signal processing member for identifying at least one characteristic of said interrogating electromagnetic signal which is representative of at least one property of at least one of (1) said borehole, and (2) said surrounding formation;
• a tubular member of coupling in a selected position within said drillstring and for supporting said transmitting member, said receiving member, and said signal processing member;
• an antenna assembly, for use in at least one of (a) said transmitting member, and (2) said receiving member, including:
• (1) an antenna pathway at least in part disposed within and surrounded by said tubular member;
• (2) an antenna member disposed in said antenna pathway;
• focus means for preferentially communicating electromagnetic energy between at least one portion of said antenna member and said borehole and surrounding formation.