Schlumberger Technology Corporation

Ralph Michael D'Angelo

Kenneth William Winkler

Sandip Bose

Smaine Zeroug

Thomas J Plona

David Linton Johnson

Chaur-Jian Hsu

Fred E Stanke

Lawrence E McGowan

Yang Liu

Oliver Clinton Mullins

Kai Hsu

Bikash Kumar Sinha

Jahir A Pabon

Philip F Sullivan

Douglas E Miller

Cengiz Esmersoy

Pierre Henri Campanac

Lennox Reid

Gale Hyslip Gustavson

Christopher V Kimball

Sergio Kostek

Harvey Williams

Nicolas Droger

Christoph Klieber

Mikhail Lemarenko

Jeffrey B Aron

Bruce A MacKay

Dustin Cavin

Peter V Coveney

Richard D Joyce

Romain C A Prioul

Lawrence M Schwartz

Hung-Wen Chang

Carl Robbins

H Charles Straub

Darryl Grigor

Aspects described herein provide for methods and apparatus for characterizing azimuthal heterogeneities in a barrier installed outside an outer casing in a borehole traversing a formation in a cased hole configuration including an inner and outer casing. The approach is based on specific attributes in sonic signals acquired with an azimuthal and axial array receiver system located inside the inner casing. The methods include slowness-time-coherence (STC) processing based on specific arrivals identified in data acquired by axial arrays associated with multiple azimuthal sections of the receiver system. The specific arrivals contain STC signatures that can be examined in terms of coherence amplitude and localization within STC maps. Based on specific attributes in the sonic signals, an azimuthal coverage of the outer casing annular contents can be created.

Through tubing near-field sonic measurements to map outer casing annular content heterogeneities

A downhole tool including at least one transmitter, a receiver array, and a controller. Each receiver element of the receiver array is configured to apply variable amplification and a variable time delay to detected acoustic waveforms, wherein the variable amplification is controlled by an amplification factor assigned to the given receiver element, and wherein the variable time delay is controlled by a time delay assigned to the given receiver element. The controller assigns a set of amplification factors and time delays to the receiver elements of the receiver array and combines signals resulting from the application of the variable amplification and the variable time delay to the detected acoustic waveforms such that sensitivity of the receiver elements of the receiver array is focused at a desired zone-of-interest in a wellbore corresponding to the set of amplification factors and time delays assigned to the receiver elements of the receiver array.

Guided mode beamforming for probing open-hole and cased-hole well environments

A method and downhole tool is provided that uses beamforming to localize acoustic energy at a desired zone-of-interest within a wellbore traversing a subterranean formation. The tool has an array of transmitter elements configured to emit guided mode acoustic signals at variable amplitude and variable time delay, which are individually controlled by an amplitude factor and time delay assigned to respective transmitter elements. A set of amplitude factors and time delays can be assigned to the transmitter elements of the transmitter array such that the transmitter elements produce a focused acoustic beam at the desired zone-of-interest by combination of guided mode acoustic signals transmitted by the transmitter elements.

An acoustic array includes an acoustic transmitter and acoustic receivers radially or longitudinally offset from the acoustic transmitter. The acoustic array is disposed in a wellbore penetrating a subsurface formation. An acoustic signal is broadcast using the transmitter and a portion of the emitted signal is reflected by a reflector and received by the receivers. The presence or absence of fractures in the subsurface formation is inferred based on the received acoustic signal. Inferences are based on travel times and/or coherency of the received signals. Images can be made and fracture orientations determined. Frequencies in the sonic or ultrasonic range may be used. Measurements may be made while-drilling or while performing post-drilling operations. Processing may be done in real-time or post-processing may be performed on recorded data.

Fracture detection and localization using acoustic reflections

Methods and systems for identifying and locating fractures within a wellbore are described herein. One such method includes generating an acoustic wave. At least a first portion of the acoustic wave travels along a wall of the wellbore. The first portion of the acoustic wave interacts with a feature on the wall of the wellbore, such as a fracture, and generates a second acoustic wave. The second acoustic wave is detected to obtain acoustic data. A chevron pattern is identified within the acoustic data and a location for the feature is determined using the identified chevron pattern.

Method and system for fracture detection using acoustic waves

A downhole acoustic logging tool includes at least one acoustic transmitter and first and second arrays of acoustic receivers deployed on a tool body. The first array of acoustic receivers includes a plurality of axially spaced apart acoustic receivers and the second array of acoustic receivers includes a plurality of circumferentially spaced apart acoustic receivers. A method for making downhole acoustic logging measurements of a subterranean formation includes causing an acoustic logging tool to obtain axial acoustic logging measurements and circumferential acoustic logging measurements. The axial acoustic logging measurements and the circumferential acoustic logging measurements are then processed to compute each of five elastic constants of a transversely isotropic medium.

Downhole elastic anisotropy measurements

A method of logging a perforation tunnel and associated features of the perforation tunnel can include the following features. A logging device including an ultrasonic transducer is located downhole into a well. The well has a casing. The ultrasonic transducer has a focal point that is a distance from the ultrasonic transducer so as to be behind the inner face of the casing. An ultrasonic signal is projected from the ultrasonic transducer. A reflection of the ultrasonic signal is reflected from an internal portion of the perforation tunnel, the perforation tunnel extending through the casing and into formation. A transit time is measured between transmission and reception of the ultrasonic signal. A position of the ultrasonic transducer corresponding to the ultrasonic transmission and reception of the reflected signal is determined.

Method and device to measure perforation tunnel dimensions

An apparatus for acoustic imaging includes an array with a number of acoustic transducers. Each acoustic transducer transmits and receives acoustic signals. The apparatus also includes a control unit that is coupled to the array and selectively powers a number of acoustic transducers based upon standoff distance between the array and an object-of-interest (e.g., a borehole wall). In some embodiments, the control unit also varies the frequency of acoustic signals transmitted from the array using the standoff distance between the array and the object-of-interest.

System and method for acoustic imaging using a transducer array

Refracted ultrasonic waves are utilized to calculate tool standoff. An ultrasonic transmitter sends a wave toward (and into) the borehole wall at a critical incidence angle for refracted waves. The refracted wave travels along the borehole wall and continuously radiates energy back into the borehole at the critical angle. The refracted wave is detected by a receiver, and the travel time of the refracted acoustic wave from transmitter to receiver is measured and used to calculate standoff. By making repeated measurements at various azimuths (for instance, as the tool rotates), one or more caliper measurements can be made. The caliper measurements can be combined to yield two-dimensional geometry of the borehole. Measurements made at different azimuths and depths yield three-dimensional borehole geometry. Arrays of transmitter-receiver pairs can be used to obviate the need for varying azimuth.

Measuring standoff and borehole geometry

A technique for utilizing tube waves to measure sound speed of fluids and other properties in the frequency range of about 5 to 100 kHz. A drill string is equipped with a sensor tube having a cavity filled with a downhole fluid such as borehole mud or formation fluid. An acoustic transmitter and an array of acoustic receivers are mounted on the tube in direct contact with the fluid. Processing circuitry calculates a property, e.g., sound speed, of the fluid based on time-of-flight of an acoustic signal generated by the transmitter and received by the array of receivers. Alternatively change in signal phase as a function of frequency may be employed by the processing circuitry. The technique is particularly suited to measuring the sound speed of borehole mud in situ.

Measurement of sound speed of downhole fluid utilizing tube waves

The invention discloses a method of creating a polymerized composition in a well bore: providing a polymerizable composition made of a polymerization initiator and a monomer polymerizable by frontal polymerization; introducing the polymerizable composition into the wellbore; exposing the polymerizable composition to a trigger to activate the frontal polymerization; and creating the polymerized composition.

Method for treating well bore within a subterranean formation

Tube waves are used to locate and characterize a solids deposit inside a fluid-filled pipe. An acoustic tube wave pulse is transmitted along the pipe. On encountering a solids deposit, the tube wave pulse is perturbed and partially reflected by changes in the boundary conditions between the fluid and the pipe to produce two deposit-modified acoustic waves. One is a perturbed wave travelling in the same direction as the tube wave pulse. The other is a reflected wave travelling in the opposite direction. One of these deposit-modified acoustic waves is received to produce an acoustic signal. Accumulated acoustic signals are processed by Fast-Fourier Transform to produce frequency-based digital data. Phase data from the frequency-based digital data is inverted to produce slowness spectrum data. Power data from the frequency-based digital data is inverted to produce attenuation spectrum data. Spectrum data is used to locate a solids deposit in the pipe. Inversion model processing of the spectrum data is used to estimate solids deposit thickness and type.

Assessing a solids deposit in an oilfield pipe

Method and tool for producing a formation velocity image data set

In one aspect, the invention involves an acoustic logging tool for performing acoustic investigations of subsurface geological formations. In one embodiment, the tool comprises a generally longitudinally extending tool body adapted for positioning in a borehole. At least one transmitter is mounted on the tool body to emit acoustic energy. At least one receiver is also mounted on the tool body at a location axially displaced from the at least one transmitter. The receiver is adapted to receive acoustic energy. An attenuator is also positioned along the body and includes at least one cavity having a plurality of particles disposed therein. The attenuator as disclosed herein may be applied to other logging tools for protecting tool components and enhancing measurement quality. Methods for attenuating acoustic energy transmitted through the body of an acoustic logging tool or other logging tools are also disclosed.

Structures and methods for damping tool waves particularly for acoustic logging tools

A method provides for locating and measuring mechanical damage in rock surrounding a borehole by detecting one or both of reductions in ultrasonic compressional wave velocity in the rock as a function of azimuth, and by detecting focused acoustic energy in the rock from local increases in ultrasonic compressional wave amplitude resulting from velocity gradients. A first preferred embodiment uses a combination of azimuthal ultrasonic compressional wave velocity data and azimuthal ultrasonic compressional wave energy data. A second embodiment uses azimuthal ultrasonic compressional wave velocity data and omni-directional sonic velocity data, with a comparison test or a curve fitting test. A third embodiment uses azimuthal ultrasonic compressional wave energy data.

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New Fairfield, CT, United States of America

Ralph Michael D'Angelo