Steerable magnetic dipole antenna for measurement-while-drilling applications
First Claim
1. A propagation or induction antenna for creating or detecting a magnetic field and disposed within a substantially cylindrical tool, said antenna comprising at least three antenna sections disposed axially along the major axis of said tool;
- wherein(a) each of said antenna sections is oriented to create or detect a component magnetic field in a particular direction relative to said tool major axis;
(b) at least two of said antenna sections are oriented such that at least part of their respective component fields are in opposite directions;
(c) said respective component fields add together to form a resultant field; and
(d) said respective component fields are oriented to cancel said resultant field on one side of said tool and to reinforce said resultant field on the opposite side of said tool.
7 Assignments
0 Petitions
Accused Products
Abstract
A steerable or non-steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna. The antenna can also be embodied to be more sensitive to resistivity in a particular azimuthal direction.
-
Citations
27 Claims
-
1. A propagation or induction antenna for creating or detecting a magnetic field and disposed within a substantially cylindrical tool, said antenna comprising at least three antenna sections disposed axially along the major axis of said tool;
- wherein
(a) each of said antenna sections is oriented to create or detect a component magnetic field in a particular direction relative to said tool major axis; (b) at least two of said antenna sections are oriented such that at least part of their respective component fields are in opposite directions; (c) said respective component fields add together to form a resultant field; and (d) said respective component fields are oriented to cancel said resultant field on one side of said tool and to reinforce said resultant field on the opposite side of said tool. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- wherein
-
13. A method for creating or detecting a magnetic field using a propagation or induction antenna disposed within a substantially cylindrical tool, said method comprising:
-
(a) disposing at least three antenna sections axially along the major axis of said tool; (b) orienting each of said antenna sections to create or detect a component magnetic field in a particular direction relative to said major axis; (c) orienting at least two of said antenna sections such that at least part of their respective component fields are in opposite directions; and (d) adding together said respective component fields to form a resultant field;
wherein(e) said respective fields are oriented to cancel said resultant field on one side of said tool and to reinforce said resultant field on the opposite side of said tool. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A propagation or induction composite antenna for creating or detecting a magnetic field and disposed within a substantially cylindrical tool, said composite antenna comprising a plurality of antennas disposed axially along the major axis of said tool;
- wherein
(a) said plurality of antennas comprises three or more said antennas; (b) each of said antennas is oriented to create or detect magnetic fields either parallel to a major axis of said tool or perpendicular to said major axis of said tool; (c) at least a first and a second of said plurality of antennas are oriented such that their respective magnetic fields are in opposite directions, and at least a third of said plurality of antennas is oriented such that its respective magnetic field is perpendicular to the respective magnetic fields of said at least first and second antennas; (d) said respective magnetic fields are added together to form a resultant field; and (e) said respective magnetic fields are oriented to cancel said resultant field on one side of said tool and to reinforce said resultant field on the opposite side of said tool. - View Dependent Claims (26, 27)
- wherein
Specification