Abstract: System and methods for estimating properties of a geologic formation are disclosed. A preferred embodiment includes a method for estimating properties of a geologic formation, comprising the steps of: measuring a property of the formation in two or more directions along a path in the formation; obtaining directional property values for at least one spatial unit along the path in the formation based on the property measurements; and providing an anisotropy estimate of the formation from the obtained directional property values.

Abstract: A mud pulser controlled by a field applied to an electroactive fluid. The electroactive fluid is employed to act as a rapid-response brake to slow or interrupt the rotation of a mud motor or mud siren, thus creating pressure pulses in a circulating fluid. In certain embodiments, the electroactive fluid is used as a direct brake acting on a shaft rotating in a volume of electroactive fluid where the shaft is coupled to the mud motor or siren. The application of a field to the electroactive fluid impedes the rotation of the shaft, thus slowing the mud motor and creating a pressure pulse in the circulating fluid. In another embodiment, a Moineau pump circulating an electroactive fluid is coupled to the mud motor. The application of a field to the electroactive fluid slows the rotation of the pump, thus slowing the mud motor and creating a pressure pulse in the circulating fluid.

Abstract: The specification discloses a downhole tool that determines hydraulic permeability of a downhole formation taking into account one or both of the dip angle of the borehole relative to the formation, and damage to the borehole wall and invasion of borehole fluid—collectively referred to as skin.

Abstract: The specification discloses a downhole tool that determines hydraulic permeability of a downhole formation taking into account one or both of the dip angle of the borehole relative to the formation, and damage to the borehole wall and invasion of borehole fluid—collectively referred to as skin.

Abstract: A subsurface formation may be evaluated through use of data obtained from Stoneley wave propagation in the fluid column within the borehole. Either wave amplitude or phase velocity may be utilized to determine composite lithology parameters. These composite lithology parameters reflect fluid and/or formation characteristics, and functionally relate such characteristics in a manner as to facilitate the determination of formation permeability in a well logging environment.

Abstract: A system and method for signal processing are disclosed. One problem in measurement-while-drilling systems including a downhole acoustic transmitter is the presence of uphole generated noise and reflected signals. By proper spacing and timing of multiple transducers and measurements, the present invention filters from the received, corrupted signal the uphole noise and reflected signals. Thus, a more accurate depiction of the transmitted signal is generated uphole.

Abstract: A system for determining fluid flow characteristics and relaying the information to the surface. The system is ideal for use in horizontal or deviated wellbores since orientation of the wellbore with respect to the vertical will not appreciably affect the system's operation. In the described embodiment, a fluid-driven siren flowmeter is placed within a production string downstream of the location of a completion zone, the flowmeter relays representative information downstream via a fluid column to a signal detection assembly. The flowmeter includes a stationary stator, a rotatable rotor and a turbine deflector which is positioned upstream of the rotor and angularly directs the flow of passing fluid to rotate the rotor. In the case of multiple completed zones described, multiple flowmeters are sequentially mounted along the same production string, each providing signals of different characteristics.

Abstract: A self-propelled turbo siren modulator assembly is disclosed for use in an MWD system. The turbo siren includes a fixed turbine deflector located upstream from a rotor, which in turn is located upstream from a fixed stator. Drilling mud flowing through the turbine deflector causes the rotor to rotate independent of any external drive device. The rotor and stator preferably have a similar configuration, which includes at least one lobe and at least one port so that the rotor alternatively blocks or permits mud flow through the port(s) of the stator to create a cyclical acoustic wave signal, with a frequency that depends upon the number of lobes on the rotor and the velocity of the drilling mud. Encoded measurement data is modulated on the carrier frequency wave through the use of amplitude modulation, frequency modulation or phase shift modulation, or a combination thereof to maximize data rates.

Abstract: A new technique for interpreting pressure data measured during a formation test. The new technique uses an exact spherical flow model that considers the effects of flow line storage and that can be solved in closed, analytical form. This technique generates a type-curve that matches the entire measured pressure plot and that can accurately predict ultimate formation pressure during formation testing from a pressure plot that has not achieved steady state values near the formation pressure.

Abstract: The present invention provides an apparatus and method for determining geologic formation properties. A pressure wave is generated by a reciprocating piston transmitted to the formation by a probe. The pressure is sensed by a high accuracy quartz gauge in the probe. This pressure is compared to the pressure sensed at a spaced probe or to the flow rate of the piston to calculate permeability or other formation properties.

Abstract: An improved formation testing method increases the accuracy of in-situ formation pressure measurements by characterizing the mudcake properties. Specifically, after a formation tester is lowered to a desired depth within a wellbore, a pad is extended to gently abut and seal against the mudcake without disturbing the mudcake. When pressed against the mudcake, the pad experiences momentarily higher pressures, which are measured by a probe housed by the pad. These pressures may be enhanced by briefly rejecting fluids through the probe, so as to avoid disturbing the mudcake. The probe continues to measure pressure, which eventually decreases relative to hydrostatic pressure in the wellbore, due to the flow of high-pressure wellbore fluids through the mudcake.

Abstract: A self-propelled turbo siren modulator assembly is disclosed for use in an MWD system. The turbo siren includes a fixed turbine deflector located upstream from a rotor, which in turn is located upstream from a fixed stator. Drilling mud flowing through the turbine deflector causes the rotor to rotate independent of any external drive device. The rotor and stator preferably have a similar configuration, which includes at least one lobe and at least one port so that the rotor alternatively blocks or permits mud flow through the port(s) of the stator to create a cyclical acoustic wave signal, with a frequency that depends upon the number of lobes on the rotor and the velocity of the drilling mud. Encoded measurement data is modulated on the carrier frequency wave through the use of amplitude modulation, frequency modulation or phase shift modulation, or a combination thereof to maximize data rates.

Abstract: In a Measurement-While-Drilling system, selecting the fixed frequency in a pulse signal generator utilizes constructive interference to enhance the signal level in an amplitude modulated signal. The pulse generation system preferably includes a plurality of mud sirens in tandem to further enhance signal level and to provide multiple amplitude levels to increase data transmission rate.

Abstract: The acoustic detector in a mud pulse telemetry system includes a one dimensional waveguide disposed between a pressure transducer and a conduit carrying drilling fluid to a drill string. The waveguide, which may include a flexible hydraulic hose, increases the amplitude of the acoustic mud pulse signal received at the transducer located at the termination end by a factor of two or more. In addition, the waveguide may be substantially filled with a fluid having a viscosity higher than the viscosity of the drilling fluid so as to provide a means to dampen high frequency noise, and thereby improve the signal-to-noise ratio at the pressure transducer.

Abstract: An acoustic detector in a mud pulse telemetry system includes a bypass loop in parallel with a section of the main mud line that supplies drilling mud to a drill string. The detector includes a pair of pressure sensing ports in the bypass line, and one or more pressure transducers for detecting the pressure at different locations in the bypass loop so that the differential pressure can be measured. The bypass loop has a small internal passageway relative to the main mud supply line and may include a constriction so as to create two regions in the passageway that differ in cross sectional areas. Forming the pressure sensing ports in the regions of differing cross sectional areas allows the pressure transducers to more precisely detect the mud pulse signals. Because of its relatively small cross sectional area, only a small fraction of the drilling mud flows through the bypass loop. The bypass loop may thus be constructed of hydraulic hose and a relatively small rigid body having a central through bore.

Abstract: The acoustic detector in a mud pulse telemetry system includes a one dimensional waveguide disposed between a pressure transducer and a conduit carrying drilling fluid to a drill string. The waveguide, which may include a flexible hydraulic hose, increases the amplitude of the acoustic mud pulse signal received at the transducer located at the termination end by a factor of two or more. In addition, the waveguide may be substantially filled with a fluid having a viscosity higher than the viscosity of the drilling fluid so as to provide a means to dampen high frequency noise, and thereby improve the signal-to-noise ratio at the pressure transducer.

Abstract: An improved acoustic signal generator has rotor and stator elements, each having a plurality of radially-extending lobes and intervening ports relatively positioned and configured to establish fluid dynamic forces that bias the generator into an open position, thereby imparting a "stable open" characteristic to the generator. The rotor is located downstream of the stator, and rotor lobes are outwardly tapered in the downstream direction and have underlap relative to the upstream stator lobes. The invention is especially suited for use in oil industry MWD operations to communicate downhole measurement data to a well surface during drilling. In one embodiment, undercuts on the rotor lobes impart a flutter action which clears debris.