Abstract: A method for detecting stick-slip in a drillstring includes (a) measuring a parameter that is a function of a torque applied to the drillstring by a top drive system over a selected time period, the measuring being performed by at least one surface sensor that produces measurement data including torque values over a frequency range; (b) filtering out measurement data that has a frequency outside a selected frequency band, the selected frequency band including a resonant frequency of the drillstring; (c) identifying a minimum and a maximum torque value in the filtered measurement data and determining a difference of these two values; (d) determining a surface stick-slip index by dividing the difference of the maximum and minimum torque values by an average torque value over the selected time period; and (e) displaying the surface stick-slip index on a display.

Abstract: A method for detecting stick-slip in a drillstring includes (a) measuring a parameter that is a function of a torque applied to the drillstring by a top drive system over a selected time period, the measuring being performed by at least one surface sensor that produces measurement data including torque values over a frequency range; (b) filtering out measurement data that has a frequency outside a selected frequency band, the selected frequency band including a resonant frequency of the drillstring; (c) identifying a minimum and a maximum torque value in the filtered measurement data and determining a difference of these two values; (d) determining a surface stick-slip index by dividing the difference of the maximum and minimum torque values by an average torque value over the selected time period; and (e) displaying the surface stick-slip index on a display.

Abstract: A system and method is presented where a low-IF architecture can be used to allow existing wireless standards to be used for joint wireless/power-line channel transmission in the provision of diversity communications channels. Diversity combining of wireless and power-line channels can be employed, wherein the input noise to the maximum-likelihood detector can be Class A-distributed. For uncoded BPSK, the BER can be a function of PLC impulsiveness and can improve wireless-only BER by orders of magnitude when PLC SNR >10 dB. The error performance can be equivalent to BER of the static PLC channel for low wireless SNR and can improve with a slope of ?1 at high wireless SNRs. The inflection point between these two regions can occur at approximately 0 dB when PLC noise is Gaussian, and increases above 20 dB as the noise becomes more impulsive.

Abstract: A system and method is presented where a low-IF architecture can be used to allow existing wireless standards to be used for joint wireless/power-line channel transmission in the provision of diversity communications channels. Diversity combining of wireless and power-line channels can be employed, wherein the input noise to the maximum-likelihood detector can be Class A-distributed. For uncoded BPSK, the BER can be a function of PLC impulsiveness and can improve wireless-only BER by orders of magnitude when PLC SNR >10 dB. The error performance can be equivalent to BER of the static PLC channel for low wireless SNR and can improve with a slope of ?1 at high wireless SNRs. The inflection point between these two regions can occur at approximately 0 dB when PLC noise is Gaussian, and increases above 20 dB as the noise becomes more impulsive.