초록 ▼

A LWD tool is disclosed for providing an image of the borehole during drilling or during removal of the tool from the borehole. The tool includes imaging transducers which are fired based upon either time or direction. Borehole reflections are processed to determine time-of-flight to give an indicat

A LWD tool is disclosed for providing an image of the borehole during drilling or during removal of the tool from the borehole. The tool includes imaging transducers which are fired based upon either time or direction. Borehole reflections are processed to determine time-of-flight to give an indication of standoff with respect to each transducer from which the borehole geometry can be obtained. The reflections also are analyzed for other information, such as the amplitude of the reflected signal. The time-of-flight and amplitude values are encoded and stored in memory for retrieval later. In addition to the imaging transducers, the imaging assembly also includes depth transducers to obtain a micro measurement of depth downhole. The micro-depth measurements are stored and/or transmitted to the surface. In addition, a directional sensor and clock are provided downhole to correlate the firing of the transducers and the receipt of reflections. The micro-depth measurements and directional measurements preferably are used with one more image signals to check for the presence of bed boundaries intersecting the borehole. If a boundary is present, the imaging assembly applies a best fit sine wave to the image signal, from which dip angle .alpha. and dip direction are obtained. In the preferred embodiment, acoustic transducers are used as the imaging transducers, although electromagnetic transducers or other suitable transducers may be used.

대표청구항 ▼

[ We claim:] [1.] An acoustic imaging assembly for use with a bottomhole drilling assembly to obtain an image of the borehole, comprising:an imaging transducer for generating a plurality of acoustic signals that are fired radially with respect to the bottomhole assembly, said transducer also receivi

[ We claim:] [1.] An acoustic imaging assembly for use with a bottomhole drilling assembly to obtain an image of the borehole, comprising:an imaging transducer for generating a plurality of acoustic signals that are fired radially with respect to the bottomhole assembly, said transducer also receiving acoustic reflections of said plurality of acoustic signals from the borehole wall and producing electrical signals in response;a downhole processor coupled to said imaging transducer, said processor generating a signal causing said transducer to fire, and said processor receiving the electrical signals from said transducer indicative of the acoustic signal reflections, said processor analyzing said electrical signals to obtain for each acoustic signal a first signal indicative of the distance between the transducer and the borehole wall and a second signal indicative of the amplitude of the acoustic signal reflection;a memory array electrically coupled to said downhole processor, said downhole processor storing said first signal and said second signal in said memory array each time the transducer is fired and a reflection is received;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; andwherein said processor correlates for each of said plurality of acoustic signals said first signal indicative of distance and said second signal representing the amplitude of the acoustic reflection with the relative rotational bearing of the transducer and the time at which the reflections are received by the transducer.