An apparatus for sensing acoustic energy in a borehole penetrating the earth includes an optical interrogator and a sensing optical fiber having a length Ls optically coupled to the optical interrogator and configured to sense the acoustic energy to provide sensed acoustic data. The apparatus also includes a reference optical fiber having a length Lr optically coupled to the optical interrogator to provide reference data, wherein the optical interrogator corrects the sensed acoustic data using the reference data to provide corrected sensed acoustic data.

The present invention discloses a microseismic monitoring system, which includes at least a microseismic sensor, a push rod set at both ends of the microseismic sensor through the first connecting mechanism for sending the microseismic sensor into a monitoring hole, a guide mechanism installed on the push rod for guiding the microseismic sensor into the monitoring hole, and a microseismic monitoring computer connecting with the microseismic sensor signal. The microseismic sensor is reusable. The first connecting mechanism can make the push rod swing relative to the microseismic sensor. The guide mechanism is a three-roller guide mechanism. The present invention can satisfy the need of monitoring different locations in monitoring holes with large depths for multiple microseismic sensors, and solve problems of effective contact coupling between the microseismic sensors and monitoring holes, which improves the accuracy of microseismic monitoring and reduces the cost of a microseismic monitoring system.

A test system for a microseismic test of rock mass fractures provided by the present invention includes at least one microseismic sensor, a push rod provided at two ends of the microseismic sensor through a connecting mechanism for feeding the microseismic sensor into a monitoring hole , an introducing mechanism mounted on the push rod for introducing the microseismic sensor into the monitoring hole, a hydraulic system providing support hydraulic oil for the microseismic sensor, a microseismic monitoring computer connected with the signal of microseismic sensor through; the microseismic sensor includes a microseismic probe, a holding component holding the microseismic probe, a support plate and a hydraulic support mechanism; the connecting mechanism can make the push rod swing relative to the microseismic sensor, and the introducing mechanism is three-rollers introducing mechanism.

A passive array of acoustic sensors capture acoustic signals produced by sand movement. The array tool is deployed downhole where it passively listens for acoustic energy generated by sand movement in the well. Once acoustic signals are acquired, model-based frameworks are used to extract single and multiple sensor features from the acoustic signals. The extracted features are used as signatures to detect or classify the production of sand.

A method for characterizing a hydraulic fracture in a subsurface formation, includes inducing a pressure change in a well drilled through the subsurface formation. Pressure and/or a time derivative thereof is measured at a location proximate to a wellhead for a selected length of time. A conductivity of at least one fracture is determined using the measured at least one of pressure and the time derivative of pressure. A change in the determined conductivity with respect to time is determined.

A method of characterizing an inflow into a wellbore includes obtaining an acoustic signal from a sensor within the wellbore. In addition, the method includes determining a plurality of frequency domain features from the acoustic signal. Further, the method includes identifying at least one of a gas phase flow, an aqueous phase flow, or a hydrocarbon liquid phase flow using the plurality of the frequency domain features. The method also includes classifying a flow rate of the at least one of the gas phase flow, the aqueous phase flow, or the hydrocarbon liquid phase flow using the plurality of frequency domain features. The acoustic signal comprises acoustic samples across a portion of a depth of the wellbore.

Methods and systems are disclosed for monitoring operation integrity during hydrocarbon production or fluid injection operations. According to the methods and systems, received microseismic data is processed to obtain a plurality of data panels corresponding to microseismic data measured over a predetermined time interval. For each data panel, trigger values are calculated for data traces corresponding to sensor receivers of the microseismic monitoring system. At least one data panel is selected as a triggered data panel that satisfies predetermined triggering criteria. At least one triggered data panel is selected as a non-trivial data panel that satisfies spectral density criteria. A value is calculated for each of at least two event attributes of a plurality of event attributes of the event. An event score is determined based on the values of the plurality of event attributes. An event is classified into at least one event category of a plurality of event categories based on the event score.

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.

A method can include receiving mechanical information of a geologic environment and location information of natural fractures of the geologic environment; using a model of the geologic environment, calculating at least strain associated with hydraulic fracturing in the geologic environment; calculating at least microseismicity event locations based at least in part on the calculated strain; calibrating the model based at least in part on the calculated microseismicity event locations and based at least in part on measured microseismicity information associated with the geologic environment to provide a calibrated model; and, using the calibrated model, determining an increase in reactivated fracture volume associated with hydraulic fracturing in the geologic environment.

A distributed acoustic sensing method that includes sending a sequence of optical pulses along an optical fiber, of at least two different widths, demodulating backscattered light from the optical fiber to obtain interferometric phase measurements as a function of position, combining the interferometric phase measurements to obtain a set of fade-resistant phase measurements, and storing or displaying the set of fade-resistant phase measurements. A distributed acoustic sensing system that includes a transmitter that sends a sequence of optical pulses along an optical fiber, of at least two different widths, a receiver that demodulates backscattered light from the optical fiber to obtain interferometric phase measurements as a function of position and combines interferometric phase measurements to obtain a set of fade-resistant phase measurements, and a storage or display device.