Methods and systems for measuring cluster efficiency for stages of wellbores are provided herein. One method includes selecting a frequency band for generating broadband tube waves within the fluid column of the wellbore and generating the broadband tube waves within the fluid column of the wellbore using a pressure pulse generator that is hydraulically coupled to the wellbore. The method also includes recording data corresponding to the broadband tube waves and reflected broadband tube waves using pressure receivers that are hydraulically coupled to the wellbore. The pressure receivers are arranged into arrays with two or more pressure receivers in each array. The data recorded by the pressure receivers relate to characteristics of reflectors (including perforation cluster/fracture interfaces) within the wellbore. The method further includes processing the recorded data using interferometry and performing full waveform inversion(s) on the processed data to determine frequency-dependent, complex-valued reflection coefficients at each perforation cluster/fracture interface.

A method and apparatus for marine surveying. A system includes: a standard-volume source element; a large-volume source element comprising an airgun having a volume greater than 1200 cubic inches; and a long-offset survey streamer. A method includes: towing a standard-volume source element; and towing a large-volume source element; activating the large-volume source element at large shotpoint intervals; and activating the standard-volume source element at standard shotpoint intervals, wherein the large shotpoint intervals are at least twice as long as the standard shotpoint intervals. A method includes: obtaining geophysical data for a subterranean formation; and processing the geophysical data to produce an image of the subterranean formation. A method includes: obtaining a firing plan for a plurality of seismic sources, wherein: a first seismic source of the plurality comprises a large-volume source element, and a second seismic source of the plurality consists of standard-volume source elements.

A method and apparatus for marine surveying. A system includes: a standard-volume source element; a large-volume source element comprising an airgun having a volume greater than 1200 cubic inches; and a long-offset survey streamer. A method includes: towing a standard-volume source element; and towing a large-volume source element; activating the large-volume source element at large shotpoint intervals; and activating the standard-volume source element at standard shotpoint intervals, wherein the large shotpoint intervals are at least twice as long as the standard shotpoint intervals. A method includes: obtaining geophysical data for a subterranean formation; and processing the geophysical data to produce an image of the subterranean formation. A method includes: obtaining a firing plan for a plurality of seismic sources, wherein: a first seismic source of the plurality comprises a large-volume source element, and a second seismic source of the plurality consists of standard-volume source elements.

A seismic source using tuned pulse sources to form an ultra-low frequency (ULF) cluster intended for use in generating seismic energy impulses for marine seismic exploration and more specifically to improved performance by increasing low frequency output to within a range of 1 Hz to 3 Hz to provide greater penetration of the seismic signal through complex overburden such as salt or basalt.

A seismic source using tuned pulse sources to form an ultra-low frequency (ULF) cluster intended for use in generating seismic energy impulses for marine seismic exploration and more specifically to improved performance by increasing low frequency output to within a range of 1 Hz to 3 Hz to provide greater penetration of the seismic signal through complex overburden such as salt or basalt.

Method, source and shuttle configured to generate acoustic waves under water. The seismic source includes a housing; a movable shuttle located inside the housing and configured to move between a closed position and an open position along a longitudinal axis X of the housing; a compensator block located inside the housing and configured to move along the longitudinal axis X; a first static seal system configured to seal a first interface between the housing and the movable shuttle in the closed position; and a second static seal system configured to seal a second interface between the movable shuttle and the compensator block in the closed position.

Method, source and shuttle configured to generate acoustic waves under water. The seismic source includes a housing; a movable shuttle located inside the housing and configured to move between a closed position and an open position along a longitudinal axis X of the housing; a compensator block located inside the housing and configured to move along the longitudinal axis X; a first static seal system configured to seal a first interface between the housing and the movable shuttle in the closed position; and a second static seal system configured to seal a second interface between the movable shuttle and the compensator block in the closed position.

A method to generate a tube wave in a tubular system involves reciprocating a plunger in a chamber system to alternatingly increase and decrease net volume, drawing fluid from and returning the fluid to a tubular system and into and from the chamber system, to generate a tube wave, and guiding the tube wave to the tubular system. Also, a tube wave generator-sensor system has a chamber system, a plunger, a driver to reciprocate the plunger within the chamber system to generate a tube wave, a flow passage to guide the tube wave into a tubular system, and a sensor to receive the tube wave signal and/or response from the tubular system. The method and system can work with or without a firing valve and or accumulator, without adding or subtracting fluid from the tubular system.

A method to generate a tube wave in a tubular system involves reciprocating a plunger in a chamber system to alternatingly increase and decrease net volume, drawing fluid from and returning the fluid to a tubular system and into and from the chamber system, to generate a tube wave, and guiding the tube wave to the tubular system. Also, a tube wave generator-sensor system has a chamber system, a plunger, a driver to reciprocate the plunger within the chamber system to generate a tube wave, a flow passage to guide the tube wave into a tubular system, and a sensor to receive the tube wave signal and/or response from the tubular system. The method and system can work with or without a firing valve and or accumulator, without adding or subtracting fluid from the tubular system.

A system for surveying the structure beneath the seabed, comprising: a survey vessel; a streamer comprising a cable, a first set of N1 sensor groups positioned at a first end portion of the cable, the sensor groups of the first set being spaced from each other by a group interval, and a second set of N2 sensor groups positioned at a second end portion of the cable, the sensor groups of the second set being spaced from each other by the group interval; a sound source; wherein, when the system is in use, the survey vessel travels at a predetermined speed, towing the streamer and the sound source such that the sound source is positioned adjacent an intermediate portion of the cable between the first and second end portions of the cable; the sound source sends acoustic pulses at a predetermined period between pulses towards the seabed such that reflections are produced towards both the first set of sensor groups and the second set of sensor groups; and the speed of the survey vessel and the predetermined period of the sound source are selected such that the shot point interval of the sound source equals the group interval.