Abstract: A system can calculate estimated strain data for a fracture in a geological formation at each of a plurality of selected locations detectable by a strain measurement device. The system can receive real strain data from the strain measurement device for the geological formation. The system can perform a linear inversion to determine a probable distribution of fluid volume and hydraulic fracture orientation in the geological formation based on the estimated strain data and real strain data. The system can determine adjustments for a fracturing operation based on the linear inversion.

Abstract: A distributed acoustic system may comprise an interrogator which includes a single photon detector, an umbilical line comprising a first fiber optic cable and a second fiber optic cable attached at one end to the interrogator, and a downhole fiber attached to the umbilical line at the end opposite the interrogator. A method for optimizing a sampling frequency may comprise identifying a length of a fiber optic cable connected to an interrogator, identifying one or more regions on the fiber optic cable in which a backscatter is received, and optimizing a sampling frequency of a distributed acoustic system by identifying a minimum time interval that is between an emission of a light pulse such that at no point in time the backscatter arrives back at the interrogator that corresponds to more than one spatial location along a sensing portion of the fiber optic cable.

Abstract: Embodiments of a device, system and method are disclosed herein. In one embodiment, a device comprises a sample cell configured to interact a fluid sample with an ion selective substrate to modify an optical characteristic of the ion selective substrate according to an ion concentration of the fluid sample, wherein the sample cell is also configured to optically interact an illumination light with the ion selective substrate to generate a sample light; an optical element configured to interact with the sample light to provide a modified light that has a property of the fluid sample; and a detector that receives the modified light and provides an electrical signal proportional to the property of the fluid sample indicated by the modified light; and wherein the ion selective substrate comprises a membrane, the membrane configured to change an optical property in a selected wavelength range, according to the property of the fluid sample.

Abstract: A cable comprises a protective jacket and a plurality of conductor bundles symmetrically arranged within the protective jacket. The cable comprises optical fibers arranged within the protective jacket relative to the plurality of conductor bundles such that an orthogonal mode electrical field symmetry for the plurality of conductor bundles is retained.

Abstract: A densitometer in the present disclosure comprises tension measuring devices that send tension measurements to a measurement module enabling the measurement module to estimate fluid density with increased accuracy. The densitometer measures sample fluid density by vibrating the sample fluid and measuring the resonant frequency of the sample fluid, then estimating the sample fluid density based on this resonant frequency. A set of tension measuring devices affixed to a tube of the densitometer measure external forces on the tube due to O-ring seals and other operational conditions. The sample fluid density estimate uses these tension measurements to take into account O-ring friction and other external forces applied to the densitometer to improve the accuracy of the calculated density.

Abstract: Systems and methods for a treatment of chemical sensors placed in a wellbore. A method may comprise providing a chemical sensor disposed in a sensing chamber, wherein the chemical sensor is on an optical fiber installed in a wellbore; optically interrogating the chemical sensor with the optical fiber; and pumping a treatment fluid through a fluid supply line and into the sensing chamber.

Abstract: A method comprises flowing a mud into a wellbore, wherein the mud has a mud composition and has a weight in a defined range. The method includes introducing a fluid pill into the mud flowing into the wellbore, wherein the fluid pill has an injection fluid with an injection composition that is different from the mud composition. A particulate has been added to the injection fluid to increase the weight of the fluid pill to be in the defined range. After flowing the mud into the wellbore such that the fluid pill is positioned in a zone of the wellbore: filtering out the particulate from the injection fluid; injecting, after the filtering, the injection fluid into the zone; measuring a downhole parameter that changes in response to injecting the injection fluid into the zone; and determining a property of the formation of the zone based on the measured downhole parameter.

Abstract: A device including a sample cell configured to interact a fluid sample with an ion selective substrate to modify an optical characteristic of the ion selective substrate according to an ion concentration of the fluid sample is provided. The sample cell is configured to optically interact an illumination light with the ion selective substrate to generate a sample light. The device includes an integrated computational element configured to interact with the sample light to provide a modified light that has a property indicative of the ion concentration in the fluid sample; and a detector that receives the modified light and provides an electrical signal proportional to an intensity of the modified light.

Abstract: Certain aspects and features of the present disclosure relate to a communication cable for use in a wellbore. The cable can be a hybrid electro-optical cable that includes a tube including one or more optical fibers. The hybrid electro-optical cable can also include a hydrogen-delay barrier encapsulating the tube and at least one insulated conductor. An outer tube can encapsulate both the hydrogen-delay barrier and the at least one insulated conductor.

Abstract: A wellbore system includes a logging unit having a retrievable logging cable coupled to a downhole tool within a wellbore and a depth correlation unit in the downhole tool that provides current depth data for the wellbore through the retrievable logging cable for recording of a current depth by the logging unit. The wellbore system also includes a distributed acoustic sensing unit that includes a seismic processing unit and a seismic profiling unit connected to a separate optical cable of the retrievable logging cable having distributed acoustic sensing channels, wherein an assignment of the distributed acoustic sensing channels along the separate optical cable is determined by an offset distance between the current depth of a formation reference region within the wellbore and a previous reference depth of the formation reference region within the wellbore. A distributed acoustic sensing method is also included.

Abstract: A hybrid electro-optic (EO) wireline cable includes optical fibers strategically placed within to allow acoustic sensing methods as well as provide power and electrical telemetry. The hybrid EO wireline cable contains optical fibers in the interstices among symmetrically arranged electrical wire bundles to allow a hybrid EO cable to be concurrently used for electrical telemetry and optical fiber sensing without interference in a wellbore environment. This hybrid EO cable maintains electric and magnetic field symmetry which allows an optimal electrical signaling rate through orthogonal propagation modes. By placing optical fibers symmetrically inside the interstitial spaces between electrical wire bundles, the cable maintains its optimal signaling rate and avoids the mechanical and electrical limitations that would be introduced when combining electrical wires and optical fibers in a wireline cable.

Abstract: A distributed fiber sensing system and method of use. The system may comprise an interrogator configured to receive a Brillouin backscattered light from a first sensing region and a second sensing region, a first fiber optic cable optically connected to the interrogator, a proximal circulator, and a distal circulator, and a second fiber optic cable optically connected to the interrogator, the proximal circulator, and the distal circulator. The system may further comprise a downhole fiber optically connected to the first fiber optic cable and the second fiber optic cable and wherein the first sensing region and the second sensing region are disposed on the downhole fiber. The method may comprise generating and launching a light pulse from an interrogator and through a first fiber optic cable to a downhole fiber and receiving a Brillouin backscattered light from a first sensing region and a second sensing region.

Abstract: Systems and methods for a treatment of chemical sensors placed in a wellbore. A method may comprise providing a chemical sensor disposed in a sensing chamber, wherein the chemical sensor is on an optical fiber installed in a wellbore; optically interrogating the chemical sensor with the optical fiber; and pumping a treatment fluid through a fluid supply line and into the sensing chamber.

Abstract: A device including an ion-selective membrane arranged within an optical path of the device and coupled to a sample cell to interact with a fluid sample and thereby modify an optical response of the ion-selective membrane according to an ion concentration in the fluid sample, is provided. The device also includes an integrated computational element (ICE) arranged within the optical path, so that the illumination light optically interacts with the ICE and with the ion-selective membrane to provide a modified light that has a property indicative of the ion concentration in the fluid sample. A detector that receives the modified light provides an electrical signal proportional to the property of the modified light. A method and a system for using the above device are also provided.

Abstract: A system can calculate estimated strain data for a fracture in a geological formation at each of a plurality of selected locations detectable by a strain measurement device. The system can receive real strain data from the strain measurement device for the geological formation. The system can perform a linear inversion to determine a probable distribution of fluid volume and hydraulic fracture orientation in the geological formation based on the estimated strain data and real strain data. The system can determine adjustments for a fracturing operation based on the linear inversion.

Abstract: Systems and methods relate to borehole seismic studies. Traditionally, borehole seismic studies are conducted using geophones. Seismic acquisition can be performed using fiber optic Distributed Acoustic Sensing (DAS). Because DAS measures dynamic relative displacement over a gauge length, which is different from particle velocity, DAS data can be converted into an equivalent geophone output response. Operations include converting DAS data into distributed velocity, and then, converting the velocity output into an equivalent geophone response. Various aspects include separating the data into interleaving subsets, integrating each subset along the spatial coordinates, selecting a window width over which the median of each subset will be calculated and subtracted from the data, performing a spatial average or low-pass filtering over contiguous values, performing a time-domain low-pass filtering, and performing the velocity-to-geophone conversion operation.

Abstract: A device including an ion-selective membrane arranged within an optical path of the device and coupled to a sample cell to interact with a fluid sample and thereby modify an optical response of the ion-selective membrane according to an ion con-centration in the fluid sample, is provided. The device also includes an integrated computational element (ICE) arranged within the optical path, so that the illumination light optically interacts with the ICE and with the ion-selective membrane to provide a modified light that has a property indicative of the ion concentration in the fluid sample. A detector that receives the modified light provides an electrical signal proportional to the property of the modified light. A method and a system for using the above device are also provided.

Abstract: A method and system can include positioning an optical waveguide along a wellbore, and launching one or more optical signals into the waveguide at one or more optical signal frequencies and during one or more time periods, thereby resulting in one or more backscattered signals being received by the receiver, which produces a trace for each of the one of more backscattered signals. Changing an environmental condition in the wellbore, generating additional backscattered light signals at one or more frequencies after the change. Comparing the traces generated before the condition change to those generated after the change, identifying a before trace and an after trace that are substantially equal to each other and identifying a frequency difference between these traces. The frequency difference can be used to determine the amount of change in the environmental condition that occurred when the environmental change event happened.

Abstract: The subject technology relates to an in-line amplifier assembly for distributed sensing system. The subject technology includes deploying a distributed sensing tool into a wellbore, and logging the wellbore using the distributed sensing tool. The distributed sensing tool includes a first optical amplifier and a first optical filter coupled to a first single-mode optical fiber. The first optical amplifier is coupled to a first single-mode circulator for amplifying a single-mode optical signal, and the first optical filter is coupled to the first optical amplifier for filtering the amplified single-mode optical signal. The first single-mode circulator is coupleable to an interrogator for routing the single-mode optical signal to a second single-mode optical fiber and routing a reflective optical signal from a second single-mode optical fiber to the interrogator. The reflective optical signal may traverse a second optical amplifier and a second optical fiber between the first and second single-mode circulators.

Abstract: A densitometer in the present disclosure comprises a piston attached to an end of a tube of the densitometer to reduce pressure dependence of density estimates of a sample fluid. The densitometer measures sample fluid density by vibrating the tube containing sample fluid and measuring the resonant frequency of the tube, then estimating the sample fluid density based on this resonant frequency. The piston is designed with a predetermined diameter that converts pressure inside the tube to tension in the tube. This tension produces an opposite effect on the resonant frequency of the tube to that caused by the fluid pressure itself and thereby reduces pressure dependence of the sample fluid density estimates.