Schlumberger Technology Corporation

Shu-Kong Chang

Krishnamurthy Ganesan

Thomas J Plona

Peter Speier

Martin E Poitzsch

Jaideva C Goswami

Sergio Kostek

Abdurrahman Sezginer

Andrew L Kurkjian

Curtis J Randall

Gordon Lane McDaniel

Gyula Varga

Kai Hsu

Robert L Kleinberg

Henri-Pierre Valero

Peter T Wu

David C Hoyle

Alain P Dorel

Fernando Garcia-Osuna

Pierre Henri Campanac

Toru Ikegami

Chaur-Jian Hsu

James C Mayes

Vivian Pistre

Anshuman Sinha

Yoko Morikami

Jeffrey B Aron

Jean-Marie Degrange

Jean-Pierre Masson

James G L Thompson

Ramachandra Shenoy

Donald A Klasel

Ting M Lau

Martin Erich Poitzsch

Ann H Everhart

Vivian Pisre

Karan Singh

Benoit G Froelich

Methods for compression of sonic log data include STC processing, sorting peak components in the sonic data; filtering the sorted peak components to remove high-frequency portions in the peak components; and decimating the filtered peak components according to a selected ratio to produce compressed data. One method for telemetry transmission of downhole sonic log data includes sorting peak components in the sonic log data; compressing the sorted peak components to produce compressed data; packing the compressed data to produce data packets for telemetry transmission; and sending the data packets using telemetry.

Methods and systems for compressing sonic log data

Techniques for displaying sonic logging data that provide highly reliable, visual quality-control (QC) indicators. One aspect herein is directed to a display of sonic logging data corresponding to a slowness frequency analysis (SFA) projection log.

Slowness-frequency projection display and animation

A method for acquiring and analyzing time-series data using singularities is described. This method allows for the analysis of data over a wide spectrum of frequencies. Once the data is acquired in an oil field, singularities of the data are extracted; and the extracted singularities are utilized to interpret the formation properties related to the data.

Analysis of time-series data using singularities

A method for in-situ calibrating acoustic receivers while the tool is in an open or cased borehole or during a logging run in a borehole. The method and system facilitate calibrating the acoustic receivers while they are mounted to a downhole acoustic tool. Calibrating the acoustic receivers in situ provides more accurate results than previously available. The method and system provide separate compensation factors for the acoustic receivers at different frequencies and for different transmission sources. The separate compensation factors facilitate more accurate signal acquisition over a wider range of conditions.

Methods and systems for calibrating acoustic receivers

The present invention relates generally to an apparatus and method for obtaining an azimuthally resolved nuclear magnetic resonance measurement of an earth formation traversed by a borehole. The measurement can be made while drilling or using a wireline tool. A receiving rf antenna having a non-axisymmetric response pattern is used to obtain the azimuthally resolved nuclear magnetic resonance measurement. The antenna employs axial currents which excite an azimuthally oriented rf magnetic field. For this situation, the static magnetic field is either radial or axial in its orientation. The antenna generates a relatively long, in axial extent, region of generally uniform static field magnitude and polarization in the formation. The present invention facilitates low profile antenna configurations that can permit dispensing with the reduction of the inner diameter of the drill collar at the rf antenna location.

Nuclear magnetic resonance logging with azimuthal resolution

An actively controlled rotary steerable drilling system for directional drilling of wells including a tubular rotary tool collar having rotatably mounted thereabout a substantially non-rotatable sliding sleeve incorporating a plurality of elastic coupling members to maintain the sliding sleeve in coupled relation with the borehole wall during drilling. An offsetting mandrel is supported within the tool collar by a knuckle joint for pivotal movement and is rotatably driven by the tool collar and has a lower end extending from the collar and adapted for support of a drill bit. To achieve controlled steering of the rotating drill bit, orientation of the drilling tool is sensed by navigation sensors and the offsetting mandrel is maintained geostationary and selectively axially inclined relative to the tool collar by orienting it about the knuckle joint responsive to navigation sensors. An alternator and a hydraulic pump, located within the tool collar, are driven by a power source driven by the flowing drilling fluid to produce electric power and hydraulic pressure for supplying electrical power for the electronics package of the tool and for actuation of hydraulic system components. Hydraulic cylinder and piston assemblies, actuated by tool position signal responsive servo-valves, control the angular position of the offsetting mandrel with respect to the tool collar. The hydraulic pistons are servo-controlled responsive to signal input from the navigation sensors and from other tool position sensing systems which provide real-time position signals to the hydraulic position control system.

Rotary steerable well drilling system utilizing hydraulic servo-loop

Apparatus and method are disclosed for determining a nuclear magnetic resonance property of formations surrounding a borehole while drilling the borehole with a rotating drill bit on a drill string. An embodiment of the method includes the following steps: providing a logging device in the drill string, the logging device being rotatable with the drill string or a portion of the drill string, the logging device having a rotational axis; producing a static magnetic field and an RF magnetic field at the logging device, the static and RF magnetic fields having mutually orthogonal components in an investigation region in the formations surrounding the logging device, the magnitudes of the static and RF magnetic fields in the investigation region being substantially rotationally invariant as the logging device rotates around its axis; receiving nuclear magnetic resonance spin echoes at at least one circumferential sector on the logging device; and determining a nuclear magnetic resonance property of the formations, for different portions of the investigation region, from the received nuclear magnetic resonance spin echoes.

A logging-while-drilling tool contains a pulsed nuclear magnetic resonance (NMR) device for evaluating earth formations. An antenna of the pulsed NMR device is electromagnetically coupled with a drill collar of the tool for evaluating earth formations. In this way, the antenna generates a magnetic dipole parallel to a surface of the drill collar and the drill collar enhances the electromagnetic field generated by the antenna.

Pulsed nuclear magnetism tool for formation evaluation while drilling

The present invention is directed to sonic logging while drilling. A transmitter and at least one receiver are mounted on a drill collar for performing sonic investigations of the formation traversing a borehole. It has been discovered that a drill collar has a natural stop band or notch where acoustic energy propagating in this frequency range is severely attenuated. Thus, to reduce drill collar acoustic coupling, the transmitter is operated within this natural stop band of the drill collar. An imperforate stop band filter is also included between the transmitter and receiver to amplify the natural stop band. The transmitter is mounted transvere to the longitudinal axis of the drill collar, and is preferably mounted within means that reduce drill collar acoustic coupling. The transmitter preferably includes a material whose acoustic response is more favorable along its longitudinal axis relative to its radial axis, thereby directing the acoustic energy into the formation rather than the surrounding drill collar.

Method of and apparatus for sonic logging while drilling a borehole

The present invention is directed to sonic logging while drilling. A transmitter and at least one receiver are mounted on a drill collar for performing sonic investigations of the formation traversed by a borehole. It has been discovered that a drill collar has a natural stop band or notch where acoustic energy propagating in this frequency range is severely attenuated. Thus, to reduce drill collar acoustic coupling, the transmitter is operated within this natural stop band of the drill collar. An imperforate stop band filter is also included between the transmitter and receiver to enhance the natural stop band. The transmitter is mounted transverse to the longitudinal axis of the drill collar, and is preferably mounted within means that reduce drill collar acoustic coupling. The transmitter preferably includes a material whose acoustic response is more favorable along its longitudinal axis relative to its radial axis, thereby directing the acoustic energy into the formation rather than the surrounding drill collar. Received acoustic energy waveforms are electronically processed to reliably detect, in the presence of drilling noise, those acoustic signals which are produced by the transmitter and transmitted through the formation.

Method of sonic logging while drilling a borehole traversing an earth

An acoustic wave transducer useful in sonic logging while drilling a borehole through an adjacent earth formation includes an array of transducer elements mounted circumferentially around a drill collar. The elements are bonded in an elastomer ring that is received in an external groove in the collar and are protected by a shield having windows. The elements are electrically connected in parallel so that when excited by an electrical pulse, the elements generate a monopole acoustic wave that propagates out into the formation. When used as a receiver, the electrically connected array of elements detect averaged acoustic waves from the formation around the circumference of the drill collar and have minimum sensitivity to acoustic multipole waves traveling through the drill collar.

Transducer for sonic logging-while-drilling

Methods for processing sonic logging data obtained by a sonic imaging tool or an MWD tool are provided. The sonic logging data are bandpass filtered and sampled according to techniques such as integer band decimation, quadrature modulation, and single side band modulation to provide compressed signals which can be reconstructed if desired. The compressed signals are alternatively stored for downloading and further processing, sent uphole for processing, or processed downhole. The processing preferably involves processing the analytic portion of the compressed signals according to an improved semblance processing technique where the semblance function is calculated over a time window utilizing coarse slowness and time sampling steps. The slowness and time sampling steps are dictated by the parameters of the bandpass filter and the inter-receiver spacing of the tool. The waveform for each receiver is preferably interpolated based on the time step size to provide those data points necessary for stacking. From the determined semblance peaks, or interpolation thereabout, the formation slowness is derived.

Downhole processing of sonic waveform information

The present invention offers methods and apparatus for low-frequency sonic borehole logging with tube waves using discrete frequency measurements. A source transducer emits sonic energy at a location in a borehole of at least one discrete frequency which induces propagation of tube waves in the borehole; sonic energy of the tube waves is received at multiple receiver locations in the borehole, the multiple receiver locations being spaced apart from one another and from the source transducer location; and at each said receiver location, the complex pressure response (amplitude and phase, or real and imaginary parts) of a receiver to the received sonic energy of the tube waves is detected relative to a phase reference. The detected complex pressure response may be processed to determine phase velocity of the tube waves in the borehole as a function of frequency, to determine attenuation of the tube waves in the borehole as a function of frequency and/or to determine attenuation and amplitude as functions of frequency. In addition, tube wave reflection coefficients near fractures, bed boundaries, etc., may be calculated. The tube wave data are useful for permeability correlation, fracture evaluation, rock rigidity studies and other purposes.

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West Redding, CT, United States of America

Shu-Kong Chang