Sun and Flare Article (Aramco)

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Item Sun and Flare Article (Aramco)
Item code
Description Aramco article on Thumpers
Manufacturer
Circa
Model
Donor Kevin Erickson
Location Houston Geoscience Center
Serial number
Taxonomy Sun and Flare

THMUP, THUMP (from Aramco’s Sun and Flare March 20, 1963) Vol. XIX. No. 11 Published by Aramco Printed by Al·Mutawa Press. Dammam Aramco has introduced a technique in seismic exploration new to Saudi Arabia Since January 12, the Exploration department, with Robert H. Ray Company personnel and equipment, has been employing a method by which a weight dropped repeatedly on the ground to a predetermined pattern generates seismic energy for producing shock waves. The conventional source of seismic wave energy is explosives. These waves help reveal the presence and type of underground structures being investigated. The weight used in the "Thumper" technique is a three ton slab of steel mounted on the back of a specially-designated truck which moves along as the weight is hoisted and dropped nine feet in a vertical fall every 12 seconds. The weight is released remotely rom from an instrument truck with a pulse transmitted by radio and synchronized with the recording cycle. An observer in the Instrument truck operate, a frequency modulated magnetic tape recorder which records the returning energies generated by the weight drop. The seismic waves are received by 288 geophones in each of two detector "patches" laid out 2,000 feet in front of and behind the instrument truck. The spacing and design of the patches are determined by careful noise analysis tests to rule out all erratic outside disturbances. The magnetic tape recordings made in the field are brought to the Ray Company offices in Dhahran where they are processed by a modified analog computer to make static and dynamic corrections. Static corrections are for elevation differences and near surface, low-velocity variations. Dynamic corrections are required because of the geometric differences between the recording stations and the drop point locations, and the increasing velocity of the seismic waves at greater depths. Finally, the central office playback corrector-analyzer turns out corrected photographic seismogram sections for interpretation by Aramco's geologists and geophysicists. The "Thumper" technique of geophysical exploration is the reverse of the method which employs explosives as a source of seismic energy. The weight drops are made along a line where the geophones used in the more conventional method are placed. In the newer seismic method the geophone patches are located at the end of each line where normally the shot boles would be. During most of the past two months the weight-dropping crew has been working in the Khursaniyah area. Recently they moved to the region around Fadhili. The crew in a normal work day bas obtained as many as 16,000 feet of subsurface coverage.

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