Western Atlas International, Inc.

Precision Energy Services, Inc.

Precision Drilling Technology Services Group, Inc.

Weatherford Technology Holdings, LLC

Scientific Drilling International, Inc.

Other

Weatherford Canada Partnership

Medhat Mickael

Dale Allen Jones

Donald Phelps

Dale Jones

John Wright

Dale A Jones

Lance Pate

Gary L Mathis

Donald A Phelps

John E Wright

An apparatus for use in acoustically assessing a wellbore, comprises a tubular body, an acoustic transmitter supported on the body, first and second acoustic receivers supported on the body with the second receiver being farther from the transmitter, wherein at least one of the inner and outer body surfaces includes a helical groove between the acoustic transmitter and the first acoustic receiver and the helical groove is filled with a composite material. The body may include a second helical groove that has the same pitch as the first helical groove and is diametrically opposite the first helical groove and may further include a third helical groove between the first and second receivers. At least one of the grooves may an opening width that is less than the maximum groove width and may have a cross-sectional area that includes a neck. The composite material may comprise tungsten particles in rubber.

Downhole acoustic device

A method for adjusting a gain of a gamma detector comprises detecting gamma radiation using the detector, recording the detected radiation as count rates in channels, wherein the last channel accumulates all counts above the maximum recorded energy; comparing the last channel count rate (LCCR) to a threshold X and, if LCCR&#x3e;X, decreasing the gain by a preset amount Y. If LCCR&#x2264;X, establishing a first estimate of a needed voltage HV1 using tool temperature and a temperature lookup table, and establishing a second estimate of a needed voltage HV2 using a backscatter peak value and a backscatter lookup table; comparing |HV1&#x2212;HV2| to a threshold Z; if |HV1&#x2212;HV2|&#x3c;Z, adjusting the gain of the gamma detector by HV2 or, if |HV1&#x2212;HV2|&#x2265;Z, adjusting the gain of the gamma detector by HV1.

Methods for gain stabilization of gamma ray measurements

An integrated logging tool includes an outer housing and an insert, the insert positioned within the outer housing. The integrated logging tool further includes a gamma sensor within the insert.

Integrated logging tool

A downhole assembly includes a drill collar, the drill collar having an outer wall and an insert, the insert positioned within drill collar. The insert has a bore therethrough. The downhole assembly further includes at least one sensor within the insert, wherein the sensor is a gamma ray detector.

Logging-while-drilling spectral and azimuthal gamma ray apparatus and methods

A data reduction method for transmission of a borehole image to the surface of the earth using restricted band widths of LWD telemetry systems. The data reduction method is based on the measurement physics rather than mathematical compression algorithms. Measured data from a sensor are fitted, within the logging tool, to a response function relating sensor response to a parameter of interest. The coefficients of the fitted response function are scaled and then telemetered to the surface. The measured data are reconstructed at the surface by combining the telemetered coefficients with the response function. A borehole image is formed by combining reconstructed reduced data. Parameters of dipping beds intersecting the borehole can be determined from the coefficients.

Data reduction of images measured in a borehole

Prior to actual use in a downhole application, gamma spectrum shape for a gamma detector can be quantified, and a relationship established between detector gain and spectrum shape. Given this relationship, the shape of a gamma spectrum measured after downhole deployment of the detector within a wellbore, for example as part of a tool in a drill string, can be quantified and compared to the pre-established relationship to determine whether the detector gain has drifted due to temperature or operating time effects. Using this relationship, a gain-affecting voltage across the detector (e.g., the photocathode voltage across the photomultiplier tube) can be adjusted to compensate for such drifts and thus to compensate for variations caused by temperature or operating time. With such compensation applied to the detector, resulting gamma spectra reliably indicate actual differences in radiation levels, thus enabling an inference of the composition of the formation at various times/depths.

Gain stabilization of radiation detectors via spectrum analysis

A monopole acoustic transmitter for logging-while-drilling comprising as a ring that comprises one or more piezoelectric arc segments. The ring is oriented in a plane whose normal is essentially coincident with the major axis of a logging tool in which it is disposed. The ring disposed within a recess on the outer surface of a short, cylindrical insert. The insert is inserted into a drill collar, rather than into the wall of the collar. The ring can comprise a continuous ring of piezoelectric material, or alternately arc segments or active ring segments of piezoelectric ceramic bonded to segments of other materials such as alumina to increase the frequency or heavy metals such as tungsten to reduce the frequency. The material and dimensions of the material used in-between the piezoelectric segments is chosen to alter the frequency of the ring.

Monopole acoustic transmitter ring comprising piezoelectric material

Acoustic data acquired in a MWD/LWD system can be compressed for transmission to the surface. The compression technique can include semblance processing acoustic signals received at a plurality of receivers spaced apart from a transmitter to generate a semblance projection at each of a plurality of depths. Peaks of the semblance projection can then be telemetered to the surface, with each peak including a slowness (velocity) value and a coherence (semblance) value. The telemetered values may be processed at the surface to generate logs as a function of depth.

Acoustic data compression technique

A logging system for measuring anisotrophic properties of the materials penetrated by a borehole. A downhole or 'logging tool' element of the system comprises a source section that comprises either a unipole or a dipole acoustic source. The receiver section comprises a plurality of receiver stations disposed at different axial spacings from the acoustic source. Each receiver station comprises one or more acoustic receivers. The system requires that the source and receiver sections rotate synchronously as the logging tool is conveyed along the borehole. Receiver responses are measured in a plurality of azimuthal angle segments and processed as a function of rotation angle of the tool. The logging system can be embodied as a logging-while-drilling system, a measurement-while-drilling system, and a wireline system that synchronously rotates source and receiver sections. All embodiments require that the acoustic source operate at a relatively high frequency.

Method and apparatus for measuring formation anisotropy while drilling

An acoustic transmitter with preferably a plurality of piezoelectric plates configured to optimized acoustic pressure output within a desired frequency range while meeting physical restrictions of LWD and MWD logging systems. The transmitter is disposed in a recess in the perimeter of a logging tool housing to reduce acoustic pressure waves transmitted directly along the tool housing and to optimize acoustic energy transmission into the borehole environs. In order to increase acoustic pressure output at a desired logging frequency range, the plurality of piezoelectric plates are connected electrically in parallel and fired simultaneously. The polarity of the plates and the wiring arrangement are such that each plate expands or contracts in a common direction during simultaneous firing by an applied voltage. The desired output frequency is obtained by selectively polarizing and dimensioning the plates within the plate assembly. The plate assembly is preferably disposed within an oil filled pressure housing that is pressure and temperature compensated.

Acoustic transmitter comprising a plurality of piezoelectric plates

A system for measuring an acoustic property of material penetrated by a well borehole. The system uses a borehole logging tool comprising preferably one acoustic transmitter and preferably a plurality of acoustic receivers. An independent measurement is used to determine azimuthal orientation of the tool within the borehole. Firings of the transmitter are based upon azimuthal orientation of the tool. Receiver responses resulting from preferably a plurality of transmitter firings per tool revolution are combined to form at least one composite transmitter response. The composite receiver response is compensated for adverse effects of the tool operating eccentered within the borehole.

Reduction of tool eccentricity effects on acoustic measurements

A monopole acoustic transmitter with at least one disc assembly with a plurality of piezoelectric discs configured to optimized acoustic pressure output within a desired frequency range while meeting physical restrictions of LWD and MWD logging systems. The transmitter is disposed in a recess or 'slot' in the perimeter of a logging tool housing to reduce acoustic pressure waves transmitted directly along the tool housing and to optimize acoustic energy transmission into the borehole environs. In order to increase acoustic pressure output at a desired logging frequency range, the plurality of piezoelectric discs in each of at least one disc assembly are connected electrically in parallel and fired simultaneously. The polarity of the discs and the wiring arrangement are such that each disc expands or contracts in a common direction during simultaneous firing by an applied voltage. The desired output frequency is obtained by selectively polarizing and dimensioning the discs within the one or more disc assemblies. Each disc assembly is preferably disposed within an oil filled pressure housing that is pressure and temperature compensated. The axis of the at least one disc assembly can be parallel or perpendicular to the major axis of the logging tool.

Monopole acoustic transmitter comprising a plurality of piezoelectric discs

Apparatus and methods for determining borehole diameter and standoff for neutron porosity logging systems. The apparatus comprises an isotopic neutron source, a single epithermal neutron detector and two thermal neutron detectors, where all detectors are at different axial spacings from the neutron source. Thermal neutron porosity is determined from the combined response of the thermal neutron detectors. Epithermal neutron porosity is determined from the response of the single epithermal neutron detector. Embodied as a wireline system, a difference between thermal neutron porosity and epithermal neutron porosity is used to compute a tool standoff, which in turn is used to correct the thermal neutron porosity for effects of standoff. Borehole size measurements are made independently and preferably with a mechanical caliper of a density tool subsection. Embodied as a LWD system, the difference between thermal neutron porosity and epithermal neutron porosity is used to correct the thermal neutron porosity measurement for both borehole diameter and radial position (standoff) of the tool within the borehole.

Growing community of inventors

Sugar Land, TX, United States of America

Medhat Mickael