Dipmeter apparatus and method using transducer array having longitudinally spaced transducers

A measurement-while-drilling system for determining a dip characteristic of formations surrounding a borehole being drilled in the earth by a drill bit at the end of a drill string, comprising:

• a drill collar in said drill string;
• a plurality of transducers mounted in said drill collar, said transducers having respectively different locations along the longitudinal direction of said drill collar;
• means for producing indications of the relative rotational orientation of said drill collar;
• means coupled with said transducers for generating a plurality of signals from measurements taken at respective ones of said plurality of transducers;
• and
• means for determining a dip characteristic of said formations from said plurality of signals and said orientation indications.

Apparatus for determining a dip characteristic of formations surrounding a borehole, comprising:

• an elongated device moveable through the borehole;
• an array of several transducers mounted in said device, said transducers having respectively different locations along the longitudinal direction of the borehole;
• means for producing indications of the relative rotational orientation of said device with respect to the longitudinal direction of the borehole;
• means coupled to with said transducers for generating signals from measurements taken at respective ones of said transducers;
• and
• means for determining a dip characteristic of said formations from said signals and said orientation indications.

A method for determining a dip characteristic of formations surrounding a borehole being drilled in the earth by a drill bit at the end of a drill string, comprising the steps of:

• providing an array of several transducers on a drill collar in said drill string, said transducers having respectively different locations along the longitudinal direction of said drill collar;
• producing indications of the relative rotational orientation of said drill collar;
• generating signals from measurements taken at respective ones of said transducers;
• and
• determining a dip characteristic of said formations from said signals and said orientation indications.

A method for determining a dip characteristic of formations surrounding a borehole being drilled in the earth by a drill bit at the end of a drill string, comprising the steps of:

• providing first and second spaced apart transducers on said drill string, said transducers having respectively different locations along the longitudinal direction of said drill string;
• producing indications of the relative rotational orientation of the drill string in the region where said transducers are located;
• generating first and second signals from measurements taken at said first and second transducers, respectively;
• and
• determining a dip characteristic of said formations from said first and second signals and said orientation indications.

A method for determining a dip characteristic of formations surrounding a borehole being drilled in the earth by a drill bit at the end of a drill string, comprising the steps of:

• providing an array of several transducers on a drill collar in said drill string, said transducers having respectively different locations along the longitudinal direction of said drill collar;
• storing first measurement signals taken with said transducers at a first longitudinal position of said array;
• storing second measurement signals taken at a second longitudinal position of said array.
• correlating said first and second measurement signals, and determining the longitudinal offset between said signals from said correlation;
• generating appended signals by combining said first and second measurement signals with a longitudinal overlap that depends on said offset;
• and
• determining said dip characteristic from said appended signals.