Fremgangsmåte og apparat til akustisk refleksjonslogging i borehull

• Main Authors: ESMERSOY, CENGIZ, CHANG, CHUNG, KANE, MICHAEL R, HSU, CHAUR-JIAN
• Format: Patent
• Language: Norwegian
• Published: 14.03.1997
• Edition: 6
• Subjects: ANALOGOUS ARRANGEMENTS USING OTHER WAVES; DETECTING MASSES OR OBJECTS; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION ORRERADIATION OF RADIO WAVES; MEASURING; PHYSICS; RADIO DIRECTION-FINDING; RADIO NAVIGATION; TESTING

A method of characterising an underground formation 16 surrounding a borehole 14 includes the steps of generating an acoustic signal with a transmitter 18 in a borehole which radiates into the formation 16 surrounding the borehole so as to reflect back to the borehole from any reflecting structures, and detecting the reflected signals at a receiver 20 in the borehole after the arrival of acoustic signals which have passes directly from the transmitter to the receiver. An apparatus for performing this method includes a tool 10 having an acoustic transmitter 18 and receiver 20, typically with a very short spacing therebetween and means for detecting acoustic signals which have been reflected from reflecting structures in the formation surrounding a borehole, after the arrival of signals which pass directly from the transmitter to the receiver. Transmitter arrays 18', receiver arrays and tube wave attenuators 22 may be used.