Importance

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Abstract

An inflatable attenuator having an inflatable resilient bladder enclosed by a perforated protective cylindrical housing is positioned in a liquid column in a well below (and if desired another inflatable attenuator is also positioned above) an impulsive energy source in the liquid column. The housing has an exterior diameter slightly less than the interior diameter of the well. The bladder is inflated when in the liquid column by gas supplied from a pressurized gas container attached to the attenuator or is supplied with pressurized gas through a hose line from a source of pressurized gas located on the surface of the Earth near the mouth of the well. A pressure-regulator responsive to the ambient hydrostatic pressure in the liquid column near the pressure regulator serves to maintain the pressure of the gas within the bladder at a regulated pressure at least equal to the ambient pressure in the liquid column where it is located. A pressure-relief valve releases pressurized gas from the bladder to prevent the pressure inside of the bladder from exceeding a predetermined differential in pressure between the inside of the bladder and ambient hydrostatic pressure so that the bladder will not rupture when the attenuator is being elevated in the well. The inflated bladder attenuates tube waves traveling along the liquid column in the well from an impulsive source of seismic energy waves when employed in the liquid column above or below the energy source. The upwardly traveling tube waves may alternatively be dissipated by releasing numerous gas bubbles in the upper portion of the liquid column to generate a bubble barrier in the upper portion of the liquid column. A further embodiment includes two bladders, including a tapered upper bladder which flares outwardly and downwardly and a cylindrical lower bladder. The perforated protective housing is omitted, and enlarged annular shoulders protect these bladders from abrasion against the wall of the well.

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First Claim