A method for automatically selecting a frequency band for transmission of a mud pulse telemetry signal includes transforming acquired transducer measurements from a time domain to a frequency domain to obtain a spectrum of measurements. The spectrum of measurements is processed to compute a total energy in band and a standard deviation of the power spectral density in band for a plurality of frequency bands. A ratio of the total energy in band to the standard deviation acquiring a plurality of transducer measurements of transmitted mud pulse telemetry pressure pulses and of the power spectral density in band is computed for at least two of the plurality of frequency bands. The frequency band having the highest computed ratio is selected and automatically downlinked to a downhole mud pulse telemetry transmitter.

A method for estimating in real time the geomechanical properties using drilling data and an accurate drilling model. An initial structural framework and initial distribution of the geomechanical and other rock properties is adjusted in real time by estimating accurately the corrected mechanical specific energy (CMSE), which is then used to estimate the geomechanical and other rock properties. For example, the updated geomechanical model can be used to geosteer the well toward the brittle zones that will achieve the best stimulation when using hydraulic fracturing in unconventional wells.

An electrically passive device and method for in-situ acoustic emission, and/or releasing, sampling and/or measuring of a fluid or various material(s) is provided. The device may provide a robust timing mechanism to release, sample and/or perform measurements on a predefined schedule, and, in various embodiments, emits an acoustic signal sequence(s) that may be used for triangulation of the device position within, for example, a hydrocarbon reservoir or a living body.

A method for revealing anomalous discontinuity interfaces in pore pressures in non-drilled geological formations and an implementing system. The method includes generating, by an electroacoustic transducer, first pressure sound waves and receiving a reflected signal of such first pressure sound waves generated by at least one discontinuity interface due to passage from first to second different geological formations situated successively along an emission direction of the electroacoustic transducer; calculating speed of the first pressure sound waves generated and distance between the electroacoustic transducer and the at least one discontinuity interface; generating, by the electroacoustic transducer, second pressure sound waves and revealing the electrical impedance induced at terminals of the electroacoustic transducer; estimating, based on the electrical impedance revealed, plural parameters characteristic of the first and second geological formation; estimating pressure of the second geological formation based on the sound speed and distance calculated and the plural characteristic parameters estimated.

Systems and methods for forming sonic images of a subterranean region and disclosed. The method may include acquiring, using a borehole sonic tool, a full-waveform sonic dataset pertaining to a borehole penetrating the subterranean region receiving the full-waveform sonic dataset, obtaining a sonic velocity model pertaining to the subterranean region, and obtaining a trajectory for the borehole, wherein the trajectory characterizes a spatial path of the borehole through the subterranean region in a first coordinate system, and transforming the sonic velocity model from the first coordinate system into a second coordinate system. The method further includes forming a sonic image in the second coordinate system from the sonic velocity model in the second coordinate system and the full-waveform sonic dataset, transforming the sonic image from the second coordinate system into the first coordinate system; and identifying a location of a sonic reflector within the sonic image.

Systems and methods for forming sonic images of a subterranean region and disclosed. The method may include acquiring, using a borehole sonic tool, a full-waveform sonic dataset pertaining to a borehole penetrating the subterranean region receiving the full-waveform sonic dataset, obtaining a sonic velocity model pertaining to the subterranean region, and obtaining a trajectory for the borehole, wherein the trajectory characterizes a spatial path of the borehole through the subterranean region in a first coordinate system, and transforming the sonic velocity model from the first coordinate system into a second coordinate system. The method further includes forming a sonic image in the second coordinate system from the sonic velocity model in the second coordinate system and the full-waveform sonic dataset, transforming the sonic image from the second coordinate system into the first coordinate system; and identifying a location of a sonic reflector within the sonic image.

Using distributed acoustic sensing (DAS) fiber optic cable for borehole surveying and/or well ranging.

This disclosure describes a method of calculating fluid distribution from a hydraulically fractured well, especially during a plug-and-perf hydraulic fracturing operation. The Distributed Acoustic Sensing (DAS) data is used to quantify the fluid distribution in separate perf clusters during fracturing, and the result can be used for completion design and optimization, hydraulic fracturing, and ultimately for oil and gas production.

The invention relates to DAS observation has been proven to be useful for monitoring hydraulic fracturing operations. While published literature has shown focus on the high-frequency components (>1 Hz) of the data, this invention discloses that much of the usable information may reside in the very low frequency band (0-50 milliHz). Due to the large volume of a DAS dataset, an efficient workflow has been developed to process the data by utilizing the parallel computing and the data storage. The processing approach enhances the signal while decreases the data size by 10000 times, thereby enabling easier consumption by other multi-disciplinary groups for further analysis and interpretation. The polarity changes as seen from the high signal to noise ratio (SNR) low frequency DAS images are currently being utilized for interpretation of completions efficiency monitoring in hydraulically stimulated wells.

This disclosure describes a method of combining DAS and DTS data to accurately estimate borehole temperature. The described method takes advantage of the thermal sensitivity of DAS signal in the low-frequency band, and combines with the absolute temperature measurement from DTS, to produce a distributed temperature estimation that is up to 10000 more accurate than the current commercial solution. The DAS and DTS data should be record simultaneously at the same well. The DAS data are first low-pass filtered and then converted into temperature variation measurement. Then an accurate temperature estimation is obtained by fitting both DTS and DAS data.