Logging while drilling borehole imaging and dipmeter device

An electromagnetic imaging assembly for use with a bottomhole drilling assembly to obtain an image of the borehole, comprising:

• an imaging transducer for generating multiple electromagnetic signals that are focused radially with respect to the bottomhole assembly, said transducer also receiving induced current from the borehole caused by each of said electromagnetic signals and producing for each of said multiple electromagnetic signals an electrical signal indicative of a restivity value in response;
• a downhole processor coupled to said imaging transducer, said processor generating a signal causing said transducer to generate each of said multiple electromagnetic signals, and said processor receiving the electrical signals from said transducer indicative of each resistivity value;
• a memory array electrically coupled to said downhole processor, said downhole processor storing said each resistivity value;
• a downhole clock electrically coupled to said downhole processor for providing a clock signal to said processor;
• a directional sensor for generating directional signals that are transmitted to said processor;
• a depth transducer axially displaced from said imaging transducer a distance d, said depth transducer also generating an electromagnetic signal and receiving induced current from the borehole wall;
• and
• wherein said processor correlates said each resistivity value with the corresponding relative rotational bearing of the transducer and the corresponding time at which each resistivity value is received by the transducer.

An LWD tool for use in a bottomhole drilling assembly, said bottomhole drilling assembly being operable to drill a wellbore through underground formations, comprising:

• a first transducer array for receiving waves reflected from the wellbore wall, from which borehole images can be determined;
• a second transducer array for receiving waves reflected from the wellbore wall, from which micro-depth can be determined;
• a directional sensor for correlating the relative rotational bearing at which the reflected waves are received by said first transducer array and said second transducer array;
• a downhole imaging assembly electrically coupled to said first transducer array and to said second transducer array for obtaining electrical signals indicative of said reflected waves, said downhole imaging assembly including;
• a comparator for determining a time-of-flight for the reflected waves received by said first transducer array;
• a processor for receiving the electrical signals indicative of said reflected waves from said first transducer array and producing a digital signal indicative of the amplitude of said reflected wave;
• and
• a correlation device for correlating the electrical signals indicative of said reflected waves from said second transducer array and producing a signal indicative of the micro-depth that the tool moved within the wellbore.

An acoustic logging-while-drilling tool for obtaining an image of the borehole being drilled, and for determining a dip angle .THETA. for bed boundaries intersecting the borehole, comprising:

• a directional sensor for generating directional signals indicative of rotational bearing and borehole inclination .THETA.;
• imaging transducers for generating acoustic signals and for receiving acoustic signal reflections from the borehole wall to obtain electronic image signals indicative of the borehole and the borehole formation characteristics;
• depth transducers for generating acoustic signals and for receiving acoustic signal reflections from the borehole wall to obtain electronic image signals indicative of the borehole and the borehole formation characteristics;
• a depth correlation device for correlating the electronic image signals obtained from said depth transducers to determine a correlation between said electronic image signals, and in response to determining a correlation, generating a micro-depth signal indicative of the spacing between the depth transducers;
• and
• a dip processor for monitoring the electronic image signals obtained from said imaging transducers to detect the presence of a bed boundary intersecting said borehole, and receiving as input signals the depth signal from said depth correlation device and directional signals from said directional sensor to determine dip angle and dip direction.