Shell Oil Comapny

Shell Usa, Inc.

Albena Alexandrova Mateeva

Johan Cornelis Hornman

Johannis Josephus Den Boer

Jeremiah Glen Pearce

Jorge Louis Lopez

Boris Nikolaevich Kuvshinov

Jeffery Joseph Mestayer

William Birch

Paul Maarten Zwartjes

Jorge Luis Lopez

Peter Berkeley Wills

Rodney William Calvert

Andrey Victorovich Bakulin

Vladimir Grechka

Kees Hornman

Receiver-consistent scalars of seismic receiver channels are used for time-lapse monitoring of a sub-surface earth formation. Signals are induced by seismic waves propagating through the earth formation adjacent to each respective seismic receiver channel. Each seismic receiver channel is acoustically coupled to the earth formation as present directly adjacent to the location of the seismic receiver channel in question. The base receiver-consistent scalars and the monitor receiver-consistent scalars of seismic receiver channels can be outputted to reveal changes in these receiver-consistent scalars. These changes can be used to delineate information about physical changes in the subsurface earth formation. The changes in the based receiver-consistent scalars and the monitor receiver-consistent scalars may be displayed visually.

Method of time-lapse monitoring using seismic waves

A seismic receiver array has a plurality of seismic receiver channels, each coupled to a local surrounding in an earth formation. A formation-material-dependent response of each seismic receiver channel is determined, and associated with an assumed depth for the corresponding seismic receiver channel. The formation-material-dependent responses as function of the assumed depth are compared to an independent depth log of at least one petrophysical parameter of the earth formation as a function of depth along the borehole. Based on the comparison, a set of lags between said assumed depth and depth in the independent depth log is determined, that provides the best correlation between the formation-material-dependent response and the independent depth log of the at least one petrophysical parameter of the earth formation. The assumed depth of each seismic receiver channel can thus be aligned with corresponding depths in the independent depth log.

Method of calibrating depths of a seismic receiver array

A first stationary seismic receiver array is provided in a first non-vertically directed first borehole section of a first array of non-vertically directed first borehole sections, and a second stationary seismic receiver array is provided in a second non-vertically directed first borehole section of the first array of non-vertically directed first borehole sections. A seismic source assembly is moved axially through a first non-vertically directed second borehole section from at least a first position to a second position of a plurality of first borehole positions along a length of the first non-vertically directed second borehole section. The seismic source assembly contains a repeatable seismic source, which is activated when the seismic source assembly is in the first position and when the seismic source assembly is in the second position. First and second shots of seismic signals are recorded with at least each of the first and second stationary seismic receivers.

Method and system for recording seismic signals

A method may include providing a sensor in a first wellbore segment, providing a sensor in a second wellbore segment, observing upgoing acoustic waves or downgoing acoustic waves with the sensors, and separating the upgoing acoustic waves and/or the downgoing acoustic waves from a total wavefield. The first wellbore segment and the second wellbore segment may be separated by a distance. At least one of the wellbore segments may be non-vertical and/or the first wellbore segment may not be parallel to the second wellbore segment. The first wellbore segment may be part of a first set of wellbores and the second wellbore segment may be part of a second set of wellbores. The separated upgoing and downgoing acoustic waves may be used to generate deghosted data.

Method and system for acquisition of seismic data

A distributed fiber optic acoustic sensing system includes a cable having a cable length. The cable has an elongated body having an outer surface, and at least one straight optical fiber extending parallel to a longitudinal axis of the cable along the cable length; and one or more non-straight optical fibers, such as two orthogonal sinusoidal optical fibers extending along the cable length, or a helically wrapped optical fiber extending along the cable length. The sensing system further has light transmitting and receiving means optically connected to the optical fibers.

Detecting broadside acoustic signals with a fiber optical distributed acoustic sensing (DAS) assembly

A method of distributed acoustic sensing includes providing a fiber optic distributed acoustic sensing system having a cable. A straight optical fiber extends parallel to a longitudinal axis of the cable along the cable length. A helically wrapped optical fiber extends along the cable length. The method includes transmitting optical signals into and receiving backscattered signals out of the optical fibers consisting of a component of said optical signals which component has been backscattered from impurities or inhomogeneities in the optical fibers, observing changes in the backscattered signals caused by axial stretching and compressing of the optical fibers caused by an incident wave, comparing the backscattered signals of the straight optical fiber and the helically wrapped fiber, and determining, based on the comparing of the backscattered signals, a direction of wave propagation of the incident wave with respect to the fiber axis for detecting broadside waves and axial waves distinguishably.

A distributed fiber optic acoustic sensing system comprises an elongate body having an outer surface, an optical fiber disposed on the outer surface at a first predetermined wrap angle, and light transmitting and receiving means optically connected to the fiber for. The elongate body may include at least one substantially flat face, and/or a layer of swellable elastomer surrounding the body, and/or an outer elastomeric tube surrounding the elastomer layer. There may be at least one sensor pad disposed in the outer layer, the sensor pad comprising a stiffener and at least one longitudinal fiber affixed thereto or embedded therein. There may be a body of protective material surrounding the tube, which may have an outer surface that includes at least one substantially flat face and at least one sensor pad disposed in the body.

Detecting broadside acoustic signals with a fiber optical distrubuted acoustic sensing (DAS) assembly

A seismic velocity profile in a region of interest in a subsurface formation is determined using at least the following steps.

Method of determining a seismic velocity profile

A P-wave slowness-polarization data set resolving P-wave slowness against P-wave polarization angle is extracted from a multi-offset vertical seismic profiling data set. A function relating P-wave polarization angle to P-wave slowness, and being dependent on at least three free parameters, wherein in at least two of these free parameters information of shear wave velocity is absorbed together with one or more anisotropy parameters that characterize formation anisotropy is selected, and regression values found for the at least three free parameters by fitting the selected function to the P-wave slowness-polarization data set. The regression values may be utilized in a method of producing a mineral hydrocarbon fluid from an earth formation.

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Houston, TX, United States of America

Albena Alexandrova Mateeva