A method for characterizing a hydraulic fracture treatment both operationally and in a subsurface formation includes inducing a pressure change in a well drilled through the subsurface formation. At least one of pressure and a time derivative of pressure is measured in the well for a selected length of time. At least one physical parameter of at least one fracture is determined using the measured pressure and/or the time derivative of pressure. A method of evaluating hydraulic fracturing treatment and operations by monitoring resonant structures present while fracturing.

Disclosed are acoustic logging systems and methods that involve correlating broadband acoustic signals acquired by a plurality of acoustic sensors at multiple depths within a wellbore to compute covariance matrices and their eigenvalues in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, acoustic sources are detected and located based on the eigenvalues viewed as a function of depth and frequency.

The invention relates to the petroleum industry. More specifically, the invention pertains to the method of detecting zones of solid particles (sand, proppant) production in a well where the solid particles are carried by fluid and gas flows, in those cases when the solid particles production zone is situated behind an impermeable barrier and there is no direct contact between the measuring instrument and the solid particles. To implement this method, at least one well operating regime is established, which is characterised by the presence of fluid flow carrying solid particles both along the wellbore and in one or more formations. At least one instrument for objective measurements of the acoustic signal amplitude is run in or pulled out of the well either at a constant speed or with intermittent stations. The acoustic signal amplitude is measured either at stations or during running in or pulling out of the well using at least one instrument for objective measurements of the acoustic signal amplitude. The acoustic signal amplitude measurement data obtained in the well are processed, detecting amplitude peaks in the recorded acoustic signal. At each depth, the peak shapes obtained during the measurements are compared with the reference one, distinguishing only those peaks that correspond to the impacts of solid particles. The solid particles are counted and the zone of solid particles production in the wellbore is identified. During downhole measurements the number of solid particles is estimated at one-second intervals, either while running in or pulling out of the well. During downhole measurements at stations the number of solid particles is estimated for each station. The duration of a measurement at a station is 10 seconds or longer. The distance between stations is equal to the length of the instrument for objective measurement of the acoustic signal amplitude. The acoustic signal amplitude is measured using three acoustic signal amplitude measuring instruments simultaneously, with the distance between stations being three times longer than the length of the instrument for objective measurement of the acoustic signal amplitude. The instrument for objective measurement of the acoustic signal amplitude is run in or pulled out at a constant speed of maximum six meters per second for an instrument one metre long, with additional rubber centralisers being installed. To monitoring the solid particles production and select the optimal operating regime, an additional solid particles surface detector is installed. The utilisation of this invention will enhance the accuracy of solid particles detection in a well.

A system is described for calibrating fiber optic well measurements including a fiber optic waveguide disposed proximal to a wellbore, a sensor coupled to the fiber optic waveguide, the sensor configured to record a plurality of signals detected by the waveguide, and a computer system configured to calibrate the signals from the waveguide by filtering out one or more background acoustic responses from the plurality of signals. A method for calibrating the signals is also described.

A method for characterizing a hydraulic fracture treatment both operationally and in a subsurface formation includes inducing a pressure change in a well drilled through the subsurface formation. At least one of pressure and a time derivative of pressure is measured in the well for a selected length of time. At least one physical parameter of at least one fracture is determined using the measured pressure and/or the time derivative of pressure. A method of evaluating hydraulic fracturing treatment and operations by monitoring resonant structures present while fracturing. A method for characterizing hydraulic fracturing rate uses microseismic event count measured through the wellbore and its real-time implementation.

The disclosure is directed to a method of utilizing an acoustic sensing cable, such as a fiber optic distributed acoustic sensing (DAS) cable, in a borehole to detect microseismic events and to generate three dimensional fracture plane parameters utilizing the detected events. Alternatively, the method can use various categorizations of microseismic data subsets to generate one or more potential fracture planes. Also disclosed is an apparatus utilizing a single acoustic sensing cable capable of detecting microseismic events and subsequently calculating fracture geometry parameters. Additionally disclosed is a system utilizing a processor to analyze collected microseismic data to generate one or more sets of fracture geometry parameters.

The present invention describes a mechanical coupling microseismic monitoring system, which includes at least one microseismic sensor, push rods that are arranged at both ends of the microseismic sensor through a first connection mechanism to send the microseismic sensor into the monitoring hole, introduction mechanisms that are mounted on the push rods for introducing the microseismic sensor into the monitoring hole, and one microseismic monitoring computer that receives signals from the microseismic sensor; the microseismic sensor is a recoverable microseismic sensor; the first connection mechanism is a connection mechanism that can make the push rod swing relative to the microseismic sensor; the introduction mechanism is a three-roller introduction mechanism. The present invention meets the requirement of microseismic monitoring for different parts of deep monitoring hole using multiple microseismic sensors.

In order to monitor the subsoil of the earth under a target zone, seismic waves coming from an identified mobile noise source are recorded by means of at least one pair of sensors disposed on either side of the target zone, time periods are selected corresponding to the alignments of the pairs of sensors with the noise source, a seismogram of the target zone is reconstructed by interferometry based on the recorded seismic waves and on the selected time periods and an image of the subsoil of the target zone is generated using the seismogram.

The embodiments of the present application include acquiring a monitoring region and each observation point therein; partitioning the monitoring region into N layers of grids according to a seismic source positioning accuracy, wherein a side length of a grid cell of an i-th layer of grid is D/2.sup.i-1, i=1, . . . N, and D is an initial side length of the grid cell and not more than a double of a distance between the respective observation points; searching all nodes in a first layer of grid to acquire a node satisfying a preset condition therefrom; from i=2, determining and searching nodes satisfying a first preset requirement in the i-th layer of grid, to acquire a node satisfying the preset condition therefrom, until a search in an N-th layer of grid is completed, wherein a node satisfying the preset condition acquired in the N-th layer of grid is a seismic source point location.

A virtual seismic shot record is generated based at least in part on seismic interferometry of the passive seismic data. Then, a frequency bandwidth of the virtual seismic shot record is determined, wherein the frequency bandwidth comprises a plurality of frequencies. The virtual seismic shot record is transformed into a frequency-dependent seismic shot record based on a first frequency of the plurality of frequencies. Further, a phase shift is applied to the frequency-dependent seismic shot record. A first velocity model is generated from the phase shifted frequency-dependent seismic shot record. A second velocity model may be generated using full-waveform inversion (FWI). One or more depth slices are identified from the second velocity model. A seismic image is generated based on the one or more depth slices for use with seismic exploration above a region of subsurface including a hydrocarbon reservoir and containing structural features conducive to a presence, migration, or accumulation of hydrocarbons.