An untethered apparatus for measuring properties along a subterranean well includes a housing, and one or more sensors configured to measure data along the subterranean well. The data includes one or more physical, chemical, geological or structural properties in the subterranean well. The untethered apparatus further includes a processor configured to control the one or more sensors measuring the data and to store the measured data, and a transmitter configured to transmit the measured data to a receiver arranged external to the subterranean well. Further, the untethered apparatus includes a controller configured to control the buoyancy or the drag of the untethered apparatus to control a position of the untethered apparatus in the subterranean well. The processor includes instructions defining measurement parameters for the one or more sensors of the untethered apparatus within the subterranean well.

A composition sensor for measuring composition of fluid mixtures is presented. The composition sensor includes a plurality of high-brightness emission sources having respective spectrally narrow wavelength emission bands in the infrared region. The wavelength emission bands overlap absorption wavelength bands of the composition. The wavelength emission bands are wavelength multiplexed and time multiplexed prior to emission through a fluid mixture. A single optical detector senses the emitted light. The composition sensor includes arms that can rotate to measure composition at different angular position of a pipe in a lateral section of an oil well. Rotation of the arms is provided by rotation of an element of a mobile vessel to which the arm is rigidly coupled. The rotation of the arms is provided by a rotation of a nose of the mobile vessel that rotates independently from a main body of the mobile vessel.

The present disclosure is directed to articles that include one or more coated fiber(s) (i.e., fiber(s) with a cured coating disposed thereon), where the coating includes a matrix of crosslinked polymers and optionally a colorant (e.g., pigment particles or dye or both). The cured coating is a product of crosslinking a coating composition including uncrosslinked polymers (e.g., a dispersion of uncrosslinked polymers in a carrier, wherein the uncrosslinked polymers are crosslinked to form the matrix of crosslinked polymers). The present disclosure is also directed to articles including the coated fibers, methods of forming the coated fibers and articles, and methods of making articles including the coated fibers.

An example CO.sub.2 monitoring systems is configured for monitoring levels of CO.sub.2 in a wellbore. A CO.sub.2 monitoring system may include one or more laser monitoring tools. A laser monitoring tool may include an optical element to output a laser beam, a detector to receive the laser beam, a first chamber housing the optical element and detector, and a second chamber including an inlet and an outlet receive and release, respectively, wellbore fluid. The first chamber may be in fluid connection with second chamber via a gas permeable membrane. Gas may permeate from second chamber into first chamber. Gas in the first chamber is subjected to a laser beam. Absorption of light by the gas is measured, and content of gas is determined based at least in part on the amount of light absorption by the gas.

Aspects of the subject technology relate to systems and methods for optimizing telemetry schemes with a constant insensible group delay. Systems and methods are provided for receiving an acquisition including compressed data and dummy data from a downhole logging system, determining a prior decompressor queue size based on the acquisition for a plurality of time intervals, determining a decompressor data size based on the acquisition for the plurality of time intervals, and determining a delay where the prior decompressor queue size is continuously greater than or equal to the decompressor data size for the plurality of time intervals.

A long range optical fiber sensor such as a distributed acoustic sensor has a sensing fiber located remotely from the interrogator, with a length of transport fiber path connecting the two. Because no sensing is performed on the transport fiber then the pulse repetition rate from the interrogator can be high enough such that the pulse repetition rate and pulse power are optimised according to the sensing fiber length and hence sensing frequency response and sensitivity are also optimised according to the sensing fiber length.

Systems and methods for measuring flow velocity of a fluid mixture in a lateral section of an oil/gas well are presented. The flow velocity is measured by tracking movement of particles and/or features in the fluid mixture via visible and/or infrared imaging sensors of a camera-based flow sensor. According to another aspect, the imaging sensors detect back-reflected light by the particles and/or features, the light emitted by illuminators in the visible and/or infrared spectrum. According to yet another aspect, the particles are quantum dot illuminators injected into the fluid mixture, the flow velocity based on a time-of-flight of the quantum dots. The camera-based flow sensor may be rotatable to measure flow velocities at different angular positions of a pipe, rotation provided by rotation of an element of a mobile vessel to which the flow sensor is rigidly coupled.

Methods and apparatus for hydrocarbon monitoring are provided. A method that may be performed by a flowmeter or monitoring system includes receiving downhole measurements of a flowing fluid from a flowmeter; determining a standard phase fraction of the flowing fluid based on the downhole measurements from the flowmeter; receiving surface measurements of the flowing fluid; determining a surface phase fraction of the flowing fluid based on the surface measurements; comparing the standard phase fraction to the surface phase fraction; based on the comparison being greater than a predetermined threshold, using the surface measurements as a reference to adjust a speed of sound (SoS) of a first phase until a target value is achieved; and receiving additional downhole measurements of the flowing fluid from the flowmeter, wherein the flowmeter is operating using the adjusted SoS of the first phase.

Aspects of the subject technology relate to systems and methods for optimizing production flow monitoring by utilizing data driven in-situ injection. Systems and methods are provided for receiving sensor data from at least one of a distributed fiber optic sensing line positioned along a wellbore and a plurality of subsurface and surface sensors, generating flow models based on the sensor data received from the at least one of the distributed fiber optic sensing line and the plurality of subsurface and surface sensors to optimize production flow, and generating flow profiles based on the flow models and the sensor data received from the at least one of the distributed fiber optic sensing line and the plurality of subsurface and surface sensors to adjust zonal inflow device.

A method is provided. Sensor data regarding a wellbore is received from at least one of a distributed fiber optic sensing line positioned along the wellbore and a plurality of subsurface and surface sensors. Flow models are generated based on the sensor data to optimize production flow. Flow profiles are generated based on the flow models and the sensor data to adjust at least one gas lift valve.