High density source spacing using continuous composite relatively adjusted pulse

Abstract

The invention relates to continuously or near continuously acquiring seismic data where at least one pulse-type source is fired in a distinctive sequence to create a series of pulses and to create a continuous or near continuous rumble. In a preferred embodiment, a number of pulse-type seismic sources are arranged in an array and are fired in a distinctive loop of composite pulses where the returning wavefield is source separable based on the distinctive composite pulses. Firing the pulse-type sources creates an identifiable loop of identifiable composite pulses so that two or more marine seismic acquisition systems with pulse-type seismic sources can acquire seismic data concurrently, continuously or near continuously and the peak energy delivered into the water will be less, which will reduce the irritation of seismic data acquisition to marine life.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Application Ser. No. 61 / 365,631, filed Jul. 19, 2010 entitled “Unique Composite Relatively Adjusted Pulse” and U.S. Provisional Patent Application Ser. No. 61 / 365,663, filed Jul. 19, 2010 entitled “Continuous Composite Relatively Adjusted Pulse” and U.S. Provisional Patent Application Ser. No. 61 / 494,952, filed Jun. 9, 2011 entitled “High Density Source Spacing Using Continuous Composite Relatively Adjusted Pulse”, which are all incorporated herein in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]None.FIELD OF THE INVENTION[0003]This invention relates to emitting seismic energy into a marine environment that is able to travel into the seafloor and reflect from and refract through geological structures and be received and recorded by hydrophones.BACKGROUND OF THE INVENTION[0004]It is very exp...

AI Technical Summary

Benefits of technology

[0009]The invention more particularly relates to a process for acquiring seismic data and provides information about geologic structures in the earth, wherein a plurality of seismic receivers are provided to receive seismic energy and at least one pulse-type seismic source is provided to emit pulses of seismic energy into the earth. The at least one pulse-type seismic source is fired to deliver a distinctive series of pulses of seismic energy into the earth to create a seismic energy wavefield response from geologic structures in the earth where the distinctive series of pulses of seismic energy are delivered in a continual loop or near continual loop from the one pulse type seismic source in a planned order. The loop is of sufficient length to provide listening time to receive the wave field response from the geologic structures in the earth from a portion of the loop defined as a composite pulse before the distinctive series of pulses of the loop end. The loop may be restarted or may have infinite length. Moreover, the series of pulses within the loop are sufficiently distinctive such that portions of the loop are recognizably distinct from other portions of the loop and the distinctions are sufficient to distinguish the wavefield caused by the loop from seismic energy in the environment that arises from other sources. The seismic energy is received by the plurality of seismic receivers including the seismic energy wavefield response from the geologic structures in the earth and the seismic energy wavefield response received by the seismic receivers is recorded to form data traces. The data traces of recorded seismic energy are processed to separately identify within the data traces each of the composite pulses of the pulse type seismic source when the composite pulses were fired and to further separately identify a number segments of data within each loop where each segment overlaps with at least one composite pulse and by processing the segments of data provides for greater data density of the geologic structures in the earth.

Problems solved by technology

It is very expensive to acquire seismic data in marine environments.

Thus, once the survey is started, there is a lot of pressure to acquire data twenty-four hours a day, seven days a week.

A problem arises when another survey crew is collecting data in the same general area at the same time.

The two operations may contaminate one another and be forced to work out a time sharing arrangement where only one crew acquires data for a period of time and then waits while the other crew takes a turn.

A second concern in the collection of seismic data in marine environments is harm, injury or irritation of whales and other marine life due to the intensity of the energy coming off the seismic sources.

The power of these pulses in the water is presumed to be at least annoying to sea animals that use echo location like whales, dolphins and others.

Seismic surveying techniques may cause these animals to leave the area and some believe that it may be harmful to sea life.

This is particularly bad in a wide azimuth shooting where multiple vessels are towing guns and all guns are fired in a round-robin fashion.

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