Abstract: Systems and methods for determining a formation property related to formation strength and stresses are disclosed. A method for determining a formation strength includes obtaining radial formation property measurements at different wellbore pressures; generating a radial stress profile based on a formation model; generating a radial stress function from the radial stress profile; and comparing the radial formation property measurements with the radial stress function to determine the formation strength. A method for determining a formation stress profile includes deriving formation parameters from a formation radial profiling; obtaining formation log data that comprise formation density data; estimating formation stresses from the formation log data; and deriving a radial stress profile based on a formation model, the derived formation parameters, and the estimated formation stresses.

Abstract: Systems and methods for determining a formation property related to formation strength and stresses are disclosed. A method for determining a formation strength includes obtaining radial formation property measurements at different wellbore pressures; generating a radial stress profile based on a formation model; generating a radial stress function from the radial stress profile; and comparing the radial formation property measurements with the radial stress function to determine the formation strength. A method for determining a formation stress profile includes deriving formation parameters from a formation radial profiling; obtaining formation log data that comprise formation density data; estimating formation stresses from the formation log data; and deriving a radial stress profile based on a formation model, the derived formation parameters, and the estimated formation stresses.

Abstract: An apparatus for use in a wellbore comprises a housing having a longitudinal axis and a mechanism having one or more impact elements adapted to move along the longitudinal axis in an oscillating manner to impart a back and forth force on the housing to vibrate the housing. In another arrangement, an apparatus for use in a wellbore comprises a housing and at least one impact element rotatably mounted in the housing. The at least one impact element is rotatable to oscillate back and forth to impart a vibration force to the housing.

Abstract: An apparatus for use in a wellbore comprises a housing having a longitudinal axis and a mechanism having one or more impact elements adapted to move along the longitudinal axis in an oscillating manner to impart a back and forth force on the housing to vibrate the housing. In another arrangement, an apparatus for use in a wellbore comprises a housing and at least one impact element rotatably mounted in the housing. The at least one impact element is rotatable to oscillate back and forth to impart a vibration force to the housing.

Abstract: An apparatus for use in a wellbore comprises a housing having a longitudinal axis and a mechanism having one or more impact elements adapted to move along the longitudinal axis in an oscillating manner to impart a back and forth force on the housing to vibrate the housing. In another arrangement, an apparatus for use in a wellbore comprises a housing and at least one impact element rotatably mounted in the housing. The at least one impact element is rotatable to oscillate back and forth to impart a vibration force to the housing.

Abstract: Methods and apparatus are described for identifying and removing noise from borehole telemetry signals. A spectrum of the signal and of an approximated noise-free spectrum of the signals are generated and compared so as to identify frequencies at which noise occurs. The approximated spectrum is preferably generated by an averaging or integrating process which essentially results in a smoothened variant of the signal spectrum. The comparison includes dividing the signal spectrum by the approximated spectrum, and setting a threshold in the resulting dimensionless peak spectrum. The remaining parts of the peak spectrum are identified as noise. The dimensionless spectrum is found to have major advantages when having to identify noise frequencies.

Abstract: Methods and apparatus are described for recognizing wellbore telemetry signals, wherein a received analog telemetry signal is compared to a number of possible analog signals. The probability of representing the received signal is determined for each of the possible analog signals. By selecting the signal with the highest probability, the received signal is demodulated. For calculating the probability, Bayes' method or any equivalent thereof is used. In variants, this probabilistic method is used to determine the synchronization point of the telemetry signal and for controlling the noise removal therefrom. The method and apparatus show increased accuracy in recognizing and demodulating the received signals.

Abstract: A method of determining, from surface measurements, the rate of penetration .DELTA.d of a drill bit attached to a drill string suspended from a floating drilling rig by means of a suspension system and a motion compensator, the method comprising:a) determining a displacement .DELTA.s of the drill string at the surface;b) determining from the measurements a function .LAMBDA.' of drill string compliance .LAMBDA. such that .LAMBDA.'=.LAMBDA.(1-.theta.) (wherein .theta. is a contribution factor of the motion compensator to an axial force applied to the drill string at the surface);c) determining an axial force .DELTA.T in the suspension system applied at the surface;d) determining a vertical displacement .DELTA.M of the motion compensator;e) determining from the measurements a function .mu. of the motion compensator compliance .lambda..sub.M such that ##EQU1## and f) calculating the bit displacement .DELTA.d from the relationship.DELTA.d=.DELTA.s-.LAMBDA.'.DELTA.T-.mu..DELTA.M.