Schlumberger Technology Corporation

Philip Neville Armstrong

John Richard Tulett

Henry Menkiti

Mathieu Will

Neil Kelsall

Philippe Lesaffre

A technique is designed to facilitate obtaining of acoustic data. The technique comprises traversing a tool through a subterranean formation from a first depth to subsequent depths. The tool receives a seismic signal during predetermined time windows. The seismic signal is generated by a seismic source which is activated at varying times relative to the predetermined time windows based on the depth of the tool.

Methods and apparatus for improved acoustic data acquisition

Methods and apparatuses are disclosed for generating three dimensional (3D) vertical seismic profiles (VSPs) in a more time efficient manner. The methods and apparatuses enable faster and more efficient VSP surveys than previous techniques. Real-time updating of the velocity model and real-time reflection point density calculations are carried out, which are used to determine the location of the next seismic source firing. In the event the data of a particular bin has an insufficient fold, common image points (CIPs) or reflection point density, additional source firings may be carried out prior to moving the source. Further, in the event the data of a particular bin is excessive in terms of the fold, CIPs or reflection point density before the planned source firings for the bin are completed, remaining source firings for that bin may be skipped to save time and improve the efficiency of the data collection.

Real-time reflection point density mapping during three-dimensional (3D) vertical seismic profile (VSP) surveys

A method is disclosed for more accurately determining the relative bearing angle of a directional receiver in a borehole using an existing three-dimensional (3D) geological model, one or more seismic sources and a three component (3C) directional receiver. A disclosed method includes: receiving direct compressional arrivals generated by multiple source events at the directional receiver disposed in the borehole; rotating the seismic data into the true earth frame using an estimated relative bearing angle; measuring a polarization vector of the rotated seismic data; estimating an incident ray vector of the direct compressional arrivals at the directional receiver using ray-tracing through the 3D model; calculating the weighted sum of an angular difference between the polarization vector and the incident ray vector; and adjusting the estimated relative bearing angle until the angular difference between the polarization and incident ray vectors is minimized.

Model-based relative bearing estimation of three-component receivers

The invention is a method for determining the orientation of a multi-component receiver where the preferred embodiment of the method makes use of an approximation of the relative bearing angle provided by a relative bearing sensor. The method comprises the steps of scanning various angles around the approximated relative bearing angle provided by the relative bearing sensor and for each scanned angle rotating the data into the true earth frame using a given scanned angle and measuring the polarization angle of the rotated data in the horizontal plane and calculating a weighted sum of the differences between the source azimuth and the estimated azimuth from the polarization.

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Yokohama, Japan

Philip Neville Armstrong