METHOD AND SYSTEM FOR WELL VELOCITY SHOOTING AND VERTICAL SEISMIC PROFILING

摘要

S P E C I F I C A T I O NTitle: METHOD AND SYSTEM FOR WELLVELOCITY SHOOTING ANDVERTICAL SEISMIC PROFILINGInventor: PAUL CHELMINSKIABSTRACT OF THE DISCLOSUREMethod and system are provided for well velocityshooting and vertical seismic profiling utilizing mobile seismicland sources for transmitting powerful seismic energy impulsesinto the earth. A plurality of nesting pairs of tanks aretransported on a single vehicle to a well site where the tanksare unloaded and arranged in a suitable array, for example, ina linear array or uniformly spaced around the mouth of the well.The tanks or containers each have a displaceable end portionserving as a diaphragm which is placed in contact with theground near the well, and then the tanks are filled with anoncompressible liquid, usually water, at the well site. Thetotal effective mass of the liquid may be increased by addingdensity-increasing materials thereto for example "drilling mud".Air guns are suspended in the tanks submerged in the liquid therein. The air guns are fired in a predetermined manner, abruptlyreleasing pressurized gas into the liquid contained in thetanks for providing powerful seismic impulses, i.e. vibrationalwaves, which are transmitted into the ground by the displaceablediaphragms. Geophone equipment which has been lowered into thewell receives the resultant waves after they have passed throughthe geological structures near the well and have been reflectedand/or refracted or otherwise affected by such structures,andthe signals from the geophone equipment may be recorded forlater analysis and/or processed at ground level, with theobjective to determine the earth structures and possible oil-1-or gas bearing regions near the well. Advantageously, a mobilesystem is provided in which a single vehicle can provide anarray of four seismic sources positioned near the mouth of awell instead of requiring four vehicles by virtue of providingnesting pairs of tanks which can be set up at the well sitewith airguns fired therein, thus providing a very effective andconvenient method of obtaining powerful seismic signals fordeep penetration into the earth. Moreover, nesting trios or alarger multiplicity of nesting containers can advantageously beprovided for greatly increasing the vehicle capacity in termsof seismic sources per vehicle.-2-