Embodiments of the invention provide an untethered apparatus for measuring properties along a subterranean well. According to at least one embodiment, the untethered apparatus 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 appratus 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 definining measurement parameters for the one or more sensors of the untethered apparatus within the subterranean well.

Methods, systems and devices for estimating a parameter of interest in a borehole. The apparatus may include a displacement device configured for displacement responsive to the parameter of interest and environmental noise; a detector array configured to provide information comprising a first signal and a second signal both relating to the displacement; and at least one processor configured to mitigate effects of the environmental noise on the information by determining correlated portions of each corresponding signal representative of effects of common mode elements of the environmental noise on each corresponding signal. The displacement device may be an optical displacement device configured to receive a first electromagnetic beam with a first value of a beam property and a second electromagnetic beam with a second value of the beam property, which comprises a displacement element configured for displacement responsive to the parameter of interest and the environmental noise.

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

A smart frac plug assembly including an instrument plug module with a sensor for collecting data during a hydraulic fracturing process. This assembly when used in conjunction with a wireless or tubing conveyed data logger and other related recording/processing systems, provides direct measurements of pressure, temperature, observed velocity field and/or observed acceleration field in a subsurface.

Optical fiber connections and their applications in downhole assemblies are described herein. The downhole assembly includes a well completion element with an end that couples with a corresponding well completion element. An optical fiber extends along at least a portion of the well completion element and transmits an optical signal using a first mode. The well completion element includes an optical fiber connector that is coupled to the optical fiber. The connector also includes a mode converter that receives the optical signal from the optical fiber and converts the optical signal from the first mode to a second larger mode. This second larger mode may be more robustly communicated to a corresponding optical fiber connector affixed to the corresponding well completion element.

Methods and systems including a photodetector of a downhole tool for performing downhole operations are provided herein. The photodetector includes a housing configured along a carrier disposed downhole within a borehole and a graphene tunneling photodetector located within the housing configured to perform a downhole operation.

A formation monitoring well system accurately measures formation electrical properties behind the casing to determine water-oil contact positions and/or to assess the integrity of the cement seal over the life of the well. The well system includes a casing string having one or more formation monitoring modules embedded therein, each having a toroid sensor.

During operation, current is provided to the casing string, and the toroid measures the current flowing into the formation. Also, the voltage drop between the sensor and an electrode positioned between the cement layer and formation may be measured. This data may then be processed to determine the resistivities of the formation and/or cement layer, whereby the cement seal quality, water-oil contact surface position, etc. may be extracted from the results.

In a downhole environment, utilizing one or more ICE modules, in response to detecting light by one or more channels of a light to voltage converter, the detected light is converted into one or more voltages. The light has previously interacted with a downhole substance and has been processed by an integrated computational element. The one or more voltages are converted into one or more analog frequencies. The one or more analog frequencies are converted into one or more digital frequencies. One or more intensities are determined from one or more digital frequencies. One or more components of the substance are determined in response to the determined one or more intensities.

A monitoring apparatus for use in a well can include multiple segments, the segments comprising at least one buoyancy control device, at least one communication device, and at least one well parameter sensor. A method of communicating in a subterranean well can include installing at least one monitoring apparatus in the well, the monitoring apparatus including a communication device, a well parameter sensor and a buoyancy control device, and the communication device communicating with another communication device. A well monitoring system can include at least one monitoring apparatus disposed in a wellbore, the monitoring apparatus comprising multiple segments, the segments including at least one buoyancy control device, at least one well parameter sensor, and at least one communication device.

A flow assembly is deployed downhole in a casing for a cementing operation. The flow assembly has a spool with an optical cable. As cement is pumped downhole and through the flow assembly, a dart attached to the optical cable on the spool is dragged with the flow of cement. Cement flow is stopped based on signals along the optical cable that the dart is at a desired location downhole.