Simulation of stress waves in attenuating drill strings, including piezoelectric sources and sensors

Abstract

A key element in drill steering and prediction of lithology ahead-of-the-bit is the transmission of while-drilling information from the bottom of the well to the rig operator and the geophysicists. Mud-pulse telemetry, based on pressure pulses along the drilling mud and extensional waves through the drill string, is the most used technique. The last method, properly designed, could transmit data rates up to 100 bits per second, against the 1 or 2 bits per second achieved with pressure pulses. In this work, a time-domain algorithm is developed for the propagation of one-dimensional axial, torsional, and flexural stress waves, including transducer sources and sensors. In addition, the equations include relaxation mechanisms simulating the viscoelastic behavior of the steel, dielectric losses, and any other losses, such as those produced by the presence of the drilling mud, the casing, and the formation. Moreover, the algorithm simulates the passbands and stopbands due to the presence of the coupling joints and pulse distortion and delay due to nonuniform cross-section areas. Acoustic and electric pulses, generated at one location in the string, can be propagated and detected at any other location by piezoelectric and acoustic sensors, such as PCB accelerometers, clamp-on ammeters, force, and strain transducers.

Simulation of axis-symmetric seismic waves in fluid-filled boreholes in the presence of a drill string

“…5, and consists of a drill string with tool joint immersed in the drilling mud, in the presence of casing, cement, and an inhomogeneous formation. Table 1 shows the acoustic and geometrical properties of the model [8,22]. The extensions of the four meshes are r a − for the inner mud, r b − r a for the tool joint, r c − r b for the outer mud, and r d − r c for the casing-cement-formation system.…”

“…A relatively simple 1-D modeling algorithm has been proposed by Carcione and Poletto [8], who have solved the differential equations describing wave propagation through the drill string. They compute waveforms of the extensional, torsional, and flexural waves by modeling the geometrical features of the coupling joints, including piezoelectric sources and sensors.…”

Synthetic logs of multipole sources in boreholes based on the Kelvin-Voigt stress-strain relation

“…Guided waves through a borehole can be used to control the drilling conditions and to obtain the petro-physical properties of the surrounding formation (e.g. Carcione & Poletto 2000). In particular, full-waveform sonic-log tools measure the P-and S-wave velocities and attenuation factors (Paillet & Cheng 1991).…”

Computational monitoring in real time: review of methods and applications

“…The drilling-mechanics parameters commonly measured downhole are drilling fluid pressure, weighton-bit (WOB), torque-on-bit (TOB), temperature, and well size. The systems for transmitting MWD information to the surface include (Poletto and Miranda 2004): (1) Mud pulse telemetry that utilises pressure waves in the drilling fluid, (2) Electromagnetic radiation that uses electromagnetic guided waves travelled in the formations, (3) Acoustic telemetry that is based on the stress wave propagation along the drill string (Drumheller 1989;Carcione and Poletto 2000), (4) Wired pipe telemetry is the latest technology that uses insulated conducting cables embedded into the drill pipe to directly transmit the signal (Veeningen 2011;Pixton et al 2014;Shishavan et al 2016).…”