Apparatus and method for determining dip and/or anisotropy of formations surrounding a borehole

Well logging apparatus for determining dip angle and/or dip azimuth angle of formations surrounding a borehole, comprising:

• a support member adapted for movement through the borehole;
• a transmitter mounted on said support member and including a first transmitter coil having an axis which is substantially parallel to the borehole axis and a second transmitter coil having an axis which is substantially perpendicular to the borehole axis;
• a receiver mounted on said support member and including first and second receiver coils having substantially mutually orthogonal axes which are both substantially perpendicular to the borehole axis;
• means for energizing the first transmitter coil;
• means for detecting the reactive component of signals induced in each of said receiver coils as a result of energizing said first transmitter coil;
• means for energizing said second transmitter coil;
• means for detecting the reactive component of signals induced in at least one of said receiver coils as a result of energizing said second transmitter coil;
• and
• means for combining the detected signals to obtain indications of the formation dip angle and/or dip azimuth angle.

A well logging method for determining dip and/or anisotropy parameters of formations surrounding a borehole, comprising the steps of:

• suspending in a borehole on a mechanically passive support member a transmitter and receiver, the transmitter including a first transmitter coil having an axis which is substantially parallel to the borehole axis and a second transmitter coil having an axis which is substantially perpendicular to the borehole axis, and the receiver including first and second receiver coils having substantially mutually orthogonal axes which are both substantially perpendicular to the borehole axis;
• energizing the first transmitter coil;
• detecting signals induced in each of said receiver coils as a result of energizing said first transmitter coil;
• energizing the second transmitter coil;
• detecting signals induced in at least one of said receiver coils as a result of energizing said second transmitter coil;
• and
• combining the detected signals to obtain indications of the formation dip and/or anisotropy parameters.

A well logging method for determining dip angle and/or dip azimuth angle of formations surrounding a borehole, comprising the steps of:

• suspending in a borehole on a support member a transmitter and receiver, the transmitter including a first transmitter coil having an axis which is substantially parallel to the borehole axis and a second transmitter coil having an axis which is substantially perpendicular to the borehole axis, and the receiver including first and second receiver coils having substantially mutually orthogonal axes which are both substantially perpendicular to the borehole axis:
• energizing the first transmitter coil;
• detecting the reactive component of signals induced in each of said receiver coils as a result of energizing said first transmitter coil;
• energizing the second transmitter coil;
• detecting the reactive component of signals induced in at least one of said receiver coils as a result of energizing said second transmitter coil;
• and
• combining the detected signals to obtain indications of the formation dip angle and/or azimuth angle.

Well logging apparatus for determining the anisotropy of formations surrounding a borehole, comprising:

• a support member adapted for movement through the borehole;
• a transmitter mounted on said support member and including a first transmitter coil having an axis which is substantially parallel to the borehole axis and a second transmitter coil having an axis which is substantially perpendicular to the borehole axis;
• a receiver mounted on said support member and including first and second receiver coils having substantially mutually orthogonal axes which are both substantially perpendicular to the borehole axis;
• means for energizing the first transmitter coil;
• means for detecting the reactive component of signals induced in each of said receiver coils as a result of energizing said first transmitter coil;
• means for energizing said second transmitter coil;
• means for detecting the reactive component of signals induced in at least one of said receiver coils as a result of energizing said second transmitter coil;
• and
• means for combining the detected signals to obtain indications of the formation anisotropy.

A well logging method for determining the anisotropy of formations surrounding a borehole, comprising the steps of:

• suspending in a borehole on a support member a transmitter and receiver, the transmitter including a first transmitter coil having an axis which is substantially parallel to the borehole axis and a second transmitter coil having an axis which is substantially perpendicular to the borehole axis, and the receiver including first and second receiver coils having substantially mutually orthogonal axes which are both substantially perpendicular to the borehole axis;
• energizing the first transmitter coil;
• detecting the reactive component of signals induced in each of said receiver coils as a result of energizing said first transmitter coil;
• energizing the second transmitter coil;
• detecting the reactive component of signals induced in at least one of said receiver coils as a result of energizing said second transmitter coil;
• and
• combining the detected signals to obtain indications of the formation anisotropy.