A downhole tool system includes a downhole tool that includes a tool body configured to move within a wellbore, a depth detection sub-assembly and configured to generate a signal based on a known depth location of the tool body in the wellbore, an acoustic transmitter sub-assembly including an acoustic pinger configured to generate acoustic pulses, and a measurement and control sub-assembly configured to receive the signal from the depth detection sub-assembly and, based on the signal, activate the acoustic transmitter sub-assembly to initiate the acoustic pulses from the acoustic pinger. The system further includes a control system that includes a fiber optic interrogator communicably coupled to a fiber strand installed in the wellbore and configured to determine a travel time of the tool body along the fiber strand or a particular distributed acoustic sensing (DAS) channel of a plurality of DAS channels based on a detection of at least one disturbance in the fiber strand caused by the acoustic pulses.

A workflow using techniques for improving signal-to-noise ratio and decreasing interferences for Low-Frequency Distributed Acoustic Sensing is described.

Sensors for imaging boreholes via the detection of electrical and optical properties may be subject to harsh conditions downhole, such as from pressure and temperature. In addition, these sensors may be subject to impact, such as tension, elongation, and compression forces, along the wall of the borehole. The harsh conditions downhole and impacts on the sensor can lead to premature wear and even breaking. The present disclosure generally relates to an apparatus for measuring electrical and optical properties of the borehole and methods for manufacturing the apparatus.

Methods, systems, devices, and products for estimating a parameter of interest of a downhole fluid in a borehole intersecting an earth formation. Apparatus include evanescent wave measurement instruments, which may include a substrate configured for contact with a downhole fluid such that at least a portion of the substrate is immersed in the downhole fluid; a waveguide formed in an interior of the substrate and having a configuration geometrically configured to generate an interaction between the downhole fluid and an evanescent wave arising from electromagnetic energy propagating in a segment of the waveguide; and a detector configured to generate measurement information indicative of the downhole fluid in response to electromagnetic signals received from the waveguide responsive to the interaction. The interaction may result in absorption of at least a portion of the electromagnetic energy propagating in the waveguide. The waveguide may be written in the substrate using laser pulses.

Methods and systems for modifying a plug container to permit a fiber pass-through allowing data to be communicated from a pressurized environment into a non-pressurized environment. The systems and methods including surrounding a communication line with a protective sheath coupled with a top plug and a cap of a plug container including an elongated body having a flow path therethrough. The cap including a pass-through for receiving the communication line and obtaining data corresponding to one or more wellbore conditions including at least a temperature, a pressure, and a top plug location.

There are described methods, systems, and computer-readable media for detecting events in a conduit. Multiple lengths of optical fiber positioned alongside a conduit are used to detect a signal. For each length of optical fiber, interferometric data is obtained from the detected signal. The interferometric data obtained for one length of optical fiber is compared to the interferometric data obtained for one or more other lengths of optical fiber. Based on the comparison, it is determined whether the signal originated from the conduit.

In one aspect, an apparatus for determining a property of a fluid is disclosed that in one embodiment may include a transparent member having an axis and a first end substantially perpendicular to the axis and a second end having an outer surface at a first angle to the axis, a light source directing light at the first end, a detector placed spaced from the second end, the space between the second end and the detector containing a fluid, wherein the detector detects light exiting from the outer surface at a second angle to the axis and passing through the fluid, and a controller for determining the second angle from the light detected by the detector. A processor determines the bulk fluid refractive index from the light detected by the detector and a property of the fluid therefrom.

A downhole sensing method includes modulating light to form a soliton that propagates through an optical fiber acting as a sensing element that measures a downhole parameter. The method further includes obtaining scattered light created as the soliton propagates through the optic-fiber. The method further includes determining a value for a downhole parameter based on the scattered light, and displaying a representation of the value.

System and methods of controlling fluid diversion during stimulation treatments are provided. Real-time measurements are obtained from a plurality of fiber-optic data sources at a well site during a stimulation treatment being performed along a portion of a wellbore within a subsurface formation. Fracture growth and stress within the subsurface formation surrounding the portion of the wellbore are determined as the stimulation treatment is performed, based on the real-time measurements and a fully-coupled diversion model. An amount of diverter for a diversion phase of the stimulation treatment to be performed along the portion of the wellbore is determined, based on the fracture growth and the stress within the subsurface formation. The diversion phase of the stimulation treatment is performed by injecting the amount of diverter into the subsurface formation via at least one injection point located along the portion of the wellbore.

An analytical method that establishes a thermodynamic equilibrium or known dynamic relationship between the concentrations of gases, natural gas liquids and oils or pressures of gasses in an isolated zone of a shale, or group of distinct shale gas intervals, with the concentrations of fluids or pressures of gasses in a wellbore penetrating the shale interval or intervals. An analytical method for identifying the chemical composition of gas, natural gas liquids and oils and determining their origin in an isolated zone of a shale, or group of distinct shale gas intervals with the identification of chemical composition of gas, natural gas liquids and oils in a wellbore penetrating the shale interval or intervals. A surface measurement apparatus capable of performing the measurement ex-situ. A downhole measurement apparatus capable of reliably performing the measurement in-situ and a downhole straddle-packer assembly capable of isolating part of, or an entire shale interval.