Abstract: The current invention provides methods for determining the sand production rate from unconsolidated and poorly consolidated subterranean formations under varying drawdown pressures. The current invention also allows for immediate production of fluid from the subterranean formation upon determination of the sand production rate. Additionally, the current invention provides a method for determining the detrimental sand production rate and/or the maximum sand free production rate for a subterranean formation. Finally, the current invention is applicable in vertical, horizontal, deviated and multi-lateral boreholes.

Abstract: An oil and gas well drilling system is provided that includes a torque drive system having an output shaft and a drill string rotated by the torque drive system. An instrumented internal blowout preventer valve is connected between the torque drive system output shaft and the drill string. The valve includes a valve housing, and one or more measurement devices mounted to the valve housing for measuring desired drill string drilling parameters during an oil and gas well drilling operation.

Abstract: A method and apparatus for detecting torsional vibration, or stick-slip, in a drill string while drilling is described. The method comprises sampling a downhole pressure sensor and using embedded filter schemes and algorithms to determine, based on the pressure samples, whether torsional vibration is occurring in the drill string. The method may also include sending a warning signal to the surface of the well. The apparatus comprises a downhole assembly having a downhole receiver and a master controller. The downhole receiver comprises a pressure sensor, filter schemes, and algorithms for detecting torsional vibration. The downhole assembly may also include a downhole transmitter for sending a warning signal to the surface of the well.

Abstract: A system and method for acquiring seismic data are disclosed. The system comprises a controller for causing the generation of a seismic signal, where the controller has a first clock used for time-stamping a record of the generated seismic signal. A seismic receiver is deployed in a wellbore so as to detect the generated seismic signal. An atomic clock is disposed in or with the seismic receiver for time-stamping a record of the detected seismic signal. The atomic clock is synchronized with the first clock prior to being placed downhole.

Abstract: The present invention provides a downhole method and apparatus using a flexural mechanical resonator, for example, a tuning fork to provide real-time direct measurements and estimates of the viscosity, density and dielectric constant of formation fluid or filtrate in a hydrocarbon producing well. The present invention additionally provides a method and apparatus for monitoring cleanup from a leveling off of viscosity or density over time, measuring or estimating bubble point for formation fluid, measuring or estimating dew point for formation fluid, and determining the onset of asphaltene precipitation. The present invention also provides for intercalibration of plural pressure gauges used to determine a pressure differential downhole.

Abstract: A plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings firmly coupled to the outer surface of the collar. Alternatively, the mass irregularities may be rings firmly coupled to the outer collar surface by neck pieces, extending inwardly from the inner circumference of the ring. The mass irregularities may be made of steel or tungsten. In another preferred embodiment, the mass irregularities are asymmetrically coupled to an outer collar wall for providing preferential directional attenuation.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity. In one embodiment, the measurement device includes a sample flow tube, vibration source and detector mounted on the tube, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The measurement module employs the vibration sources to generate vibrations in the tube. The measurement module combines the signals from the vibration detector on the tube to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example. To measure the sample fluid density, the measurement module determines the resonant frequency of the sample flow tube. The density can then be calculated according to a formula that compensates for the temperature and pressure of the system.

Abstract: A system and method for acquiring seismic data are disclosed. The system comprises a controller for causing the generation of a seismic signal, where the controller has a first clock used for time-stamping a record of the generated seismic signal. A seismic receiver is deployed in a wellbore so as to detect the generated seismic signal. An atomic clock is disposed in or with the seismic receiver for time-stamping a record of the detected seismic signal. The atomic clock is synchronized with the first clock prior to being placed downhole.

Abstract: A method and apparatus for in-situ characterization of downhole fluids in a wellbore using ultrasonic acoustic signals. Measurements of the speed of sound, attenuation of the signal, and acoustic back-scattering are used to provide qualitative and quantitative data as to the composition, nature of solid particulates, compressibility, bubble point, and the oil/water ratio of the fluid. The tool generally comprises three sets of acoustic transducers mounted perpendicular to the direction of the flow. These transducers are capable of operating at different frequencies so that the spectrum of the acoustic signal can be optimized. The apparatus is capable of operating downhole to provide real time information as to conditions in the well.

Abstract: A method and apparatus for detecting torsional vibration, or stick-slip, in a drill string while drilling is described. The method comprises sampling a downhole pressure sensor and using embedded filter schemes and algorithms to determine, based on the pressure samples, whether torsional vibration is occurring in the drill string. The method may also include sending a warning signal to the surface of the well. The apparatus comprises a downhole assembly having a downhole receiver and a master controller. The downhole receiver comprises a pressure sensor, filter schemes, and algorithms for detecting torsional vibration. The downhole assembly may also include a downhole transmitter for sending a warning signal to the surface of the well.

Abstract: An elastic wave generator includes an excitation coil, a magnetostriction oscillator around which the excitation coil is wound and an oscillator support. The excitation coil is wound around the oscillator, which is made of laminated magnetostriction sheets having a positive strain characteristic, in which length varies directionally upon magnetic excitation. The oscillator support has a first support surface bearing against a first end surface of the magnetostriction oscillator, intersecting the direction along which the length of the magnetostriction oscillator changes and a second support surface shrink-fit against a second end surface of the magnetostriction oscillator, intersecting the direction along which the length of the magnetostriction oscillator changes. Thus, the changes in the length of the magnetostriction oscillator due to the magnetic excitation of the excitation coil appearing at the first and second end surfaces is directly supported by the first and second support surfaces.

Abstract: The present invention discloses an acoustic resonator device capable of nucleating bubbles in a formation fluid under borehole-like conditions wherein the static pressure is higher than the bubble point pressure. The device is comprised of one or more coaxial layers forming a central conduit, wherein at least one of the coaxial layers is comprised of an electro-acoustic transducer material such as including piezoelectric or magnetorestrictive materials. This device is preferably designed to be in fluid communication with a host tool to allow in-situ sampling and bubble point determination. Also disclosed is an in-situ method of fluid analysis in a borehole for determining phase characteristics of a formation fluid using the device. Cavitation may be induced using the device in either a captured volume sample or a flow-line sample.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity. In one embodiment, the measurement device includes a sample flow tube, vibration source and detector mounted on the tube, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The measurement module employs the vibration sources to generate vibrations in the tube. The measurement module combines the signals from the vibration detector on the tube to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example. To measure the sample fluid density, the measurement module determines the resonant frequency of the sample flow tube. The density can then be calculated according to a formula that compensates for the temperature and pressure of the system.

Abstract: An apparatus and method for monitoring and reporting downhole bit failure. Sensors are located on a sub assembly (which is separate from the drill bit itself but located above it on the drill string). Data from the sensors (preferably accelerometers) are collected in blocks, then analyzed in the frequency domain. The frequency domain is divided into multiple bands, and the signal power in each band is compared to that of another band to produce a ratio of powers. When a bit is operating at normal condition, most of the spectral energy of the bit vibration is found in the lowest frequency band. As a bearing starts to fail, it produces a greater level of vibration in the higher frequency bands. This change in ratios is used to determine probable bit failure. Bit failure can be indicated by a given ratio surpassing a given threshold, or by monitoring the standard deviation of the frequency ratios. When the standard deviation exceeds a certain value, a failure is indicated.

Abstract: An apparatus and system are disclosed for in situ measurement of downhole fluid flow using Doppler techniques. First, a baseline speed of sound is established as close to the desired measurement point as possible. This speed of sound measurement is then used in Doppler calculations for determining flow velocities based from induced Doppler shift resulting from fluid flow. A heterodyne receiver arrangement is preferably used for processing so that the flow direction can be determined and the detection sensitivity for low flow velocities can be enhanced. From in situ measurements, well kicks may be spotted and dealt with in real-time. In addition, current theoretical models of Theological properties may be verified and expounded upon using in situ downhole measurement techniques. Furthermore, the velocity measurements described herein can be used to recognize downhole lost circulation and/or gas/water/oil influxes as early as possible, even when the mud recirculation pumps are turned off.

Abstract: A method and apparatus for in-situ characterization of downhole fluids in a wellbore using ultrasonic acoustic signals. Measurements of the speed of sound, attenuation of the signal, and acoustic back-scattering are used to provide qualitative and quantitative data as to the composition, nature of solid particulates, compressibility, bubble point, and the oil/water ratio of the fluid. The tool generally comprises three sets of acoustic transducers mounted perpendicular to the direction of the flow. These transducers are capable of operating at different frequencies so that the spectrum of the acoustic signal can be optimized. The apparatus is capable of operating downhole to provide real time information as to conditions in the well.

Abstract: An isolator bar of acoustic instruments used in downhole applications is made of a substantially cylindrical tube of metal of the type from which downhole instrument housing is usually made. A plurality of slots are placed in the tube at angles which are between 10 to 80° angle relative to the longitudinal axis of the tube. The isolator bar is equipped with traditional mechanical means with which it is incorporated in the acoustic instrument, placed between an acoustic transducer and an acoustic sensor or sensors utilized in the instrument. The angled slots cause sound waves traveling through the isolator bar to travel through multiple and extended path to the acoustic sensor, without significantly weakening the structural strength of the isolator bar.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity and a reference cavity. In one embodiment, the measurement device includes a sample flow tube, a reference flow tube, vibration sources and detectors mounted on the tubes, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The reference flow tube is filled with a reference fluid having well-characterized properties. The measurement module employs the vibration sources to generate vibrations in both tubes. The measurement module combines the signals from the vibration detectors on the tubes to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity and a reference cavity. In one embodiment, the measurement device includes a sample flow tube, a reference flow tube, vibration sources and detectors mounted on the tubes, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The reference flow tube is filled with a reference fluid having well-characterized properties. The measurement module employs the vibration sources to generate vibrations in both tubes. The measurement module combines the signals from the vibration detectors on the tubes to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example.

Abstract: An apparatus and method for monitoring and reporting downhole bit failure. Sensors are located on a sub assembly (which is separate from the drill bit itself but located above it on the drill string). Data from the sensors (preferably accelerometers) are collected in blocks, then analyzed in the frequency domain. The frequency domain is divided into multiple bands, and the signal power in each band is compared to that of another band to produce a ratio of powers. When a bit is operating at normal condition, most of the spectral energy of the bit vibration is found in the lowest frequency band. As a bearing starts to fail, it produces a greater level of vibration in the higher frequency bands. This change in ratios is used to determine probable bit failure. Bit failure can be indicated by a given ratio surpassing a given threshold, or by monitoring the standard deviation of the frequency ratios. When the standard deviation exceeds a certain value, a failure is indicated.

Abstract: The present invention provides a method that is useful in determining the permeability of rock within a subterranean formation surrounding a borehole. The method involves the establishment of a compressional wave in the borehole rock of interest and the subsequent detection of a slow compressional wave that is directly related to the permeability of the rock. The slow compressional wave typically has a velocity of approximately 900 m/s. In contrast, the compressional waves used to make borehole measurements in the past have, velocities of approximately 2000-3000 m/s.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity and a reference cavity. In one embodiment, the measurement device includes a sample flow tube, a reference flow tube, vibration sources and detectors mounted on the tubes, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The reference flow tube is filled with a reference fluid having well-characterized properties. The measurement module employs the vibration sources to generate vibrations in both tubes. The measurement module combines the signals from the vibration detectors on the tubes to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example.

Abstract: The present invention is a system and method for generating an alarm relative to effective longitudinal behavior of a drill bit fastened to the end of a drill string driven in rotation in a well by a driving device situated at the surface, using a physical model of the drilling process based on general mechanics equations. The following steps are carried out: the model is reduced so to retain only pertinent modes, at least two values Rf and Rwob are calculated, Rf being a function of the principal oscillation frequency of weight on hook WOH divided by the average instantaneous rotating speed at the surface, Rwob being a function of the standard deviation of the signal of the weight on bit WOB estimated by the reduced longitudinal model from measurement of the signal of the weight on hook WOH, divided by the average weight on bit WOB0, defined from the weight of the string and the average weight on hook. Any danger from the longitudinal behavior of the drill bit is determined from the values of Rf and Rwob.

Abstract: A method is provided for determining the rotational stiffness of a drill string for drilling of a borehole in an earth formation, the drill string having a bottom hole assembly (BHA) and an upper end driven by a rotational drive system. The method comprises the steps of determining the time derivative of the drill string torque during drilling of the borehole at a selected time when stick-slip of the BHA occurs, determining the nominal rotational speed of the drill string at an upper part thereof and at said selected time, and determining the rotational stiffness of the drill string from a selected relationship between said time derivative of the drill string torque and said nominal rotational speed at the upper part of the drill string.

Abstract: An acoustic wave transmission system comprises an acoustic wave generating metal tubular member for converting information about the bottom of a borehole, which is obtained by a bottom hole sensor, into an acoustic wave. The acoustic wave generating metal tubular member includes a acoustic wave generating mechanism having at least a magnetostrictive oscillator which is mounted in a recess formed in an outer wall of the acoustic wave generating metal tubular member, and on which a compressive load is imposed by means of a pre-load mechanism using a vise. The magnetostrictive oscillator is constructed of a stack of thin plates each made of a metal magnetostrictive material having a property of increasing its dimensions when magnetized, the thin plates being bonded together by a heat-resistant adhesive. The magnetostrictive oscillator can thus have a buckling strength large enough to resist the compressive load imposed thereon by the pre-load mechanism and a stress due to a strain caused in itself.

Abstract: The invention provides a method of detecting, at the surface, the occurrence of torsional vibration in a bottomhole assembly mounted on the drill string of a rotary drilling system. The method includes the steps of: ascertaining natural frequencies of torsional vibration of the bottomhole assembly prior to drilling, and noting at least one reference frequency for an integer wavelength mode of torsional vibration of the bottomhole assembly. During subsequent drilling, the drill string mean square torque at the surface is monitored for a bandwidth around the reference frequency. It is found that peaks in the mean square torque, close to the reference frequency, are indicative of the occurrence of torsional vibration in the bottomhole assembly.

Abstract: A downhole drilling efficiency sensor (DES) apparatus for use with drilling operations in oil and gas exploration, that accurately measures important drilling parameters at or near the drill bit in order to increase the effectiveness and productivity of the drilling operation. The parameters measured include weight-on-bit (WOB), torque-on-bit (TOB), bending-on-bit (BOB), annulus pressure, internal bore pressure, triaxial vibration (DDS—drilling dynamics sensor), annulus temperature, load cell temperature, and drill collar inside diameter temperature or thermal gradient across such drill collar. The direction of the bending-on-bit measurement is also determined with respect to the low side of the hole while rotating (or stationary) by using a triaxial vibration sensor and magnetometer array. Each of the parameters are known to be important factors in determining the direction, rotation, and rate of drilling.

Abstract: A method for determining the existence of a whirling condition during drilling of a borehole provides real time determination of destructive conditions of a bottom hole assembly during drilling. The method measures the acceleration of the bottom hole assembly to determine one or more acceleration values. Sensors also measured with rotation speed of the bottom hole assembly to determine at least one rotation of speed value. Based upon this information calculations are performed to determine a radius or diameter of rotation in the time domain which will indicate and identify the whirling condition within the bottom hole assembly. Types of whirl conditions identifiable are forward and backward whirl with and without slip. The method assumes forward whirl and backward whirl and creates a plot for each then overlaps the plot which provides an accurate representation of the condition of the bottom hole assembly while drilling.