Microresistivity scaning borehole wall image-forming logging tool

A microresistivity logging device for scanning image of borehole wall is an important logging device of imaging of borehole wall. The device uses one hundred and fifty small electrodes on six plates to transmit current to formation of borehole wall and then collects current signals transmitted by each electrode. The differences of fluid in the rock and composition and texture of the rock contacted by the electrodes cause variation of current and the variation of current reflects the variation of the rock resistivity. After high-density sampling and high-resolution imaging, the imaging of borehole wall of resistivity can be displayed. The vertical resolution of the imaging can reach few millimeters and the imaging has intuitive visual function. Correct analysis of distribution characteristics and types of fractures, bedding of formation, division of sand-bud thin interbedding, reservoir effective thickness, variation of order of depositing particles and sizes of gravel particles can be made from the imaging of