Abstract: A plunger lift control system for improving the output efficiency of an oil or gas well by a real-time reporting arrangement, the system comprising: a tubing string having an upper end and a lower end, the tubing string arranged within a well casing for receiving a plunger traveling therethrough, a plunger having a sound generating function therewith, so as to transmit a real-time lower-end location signal from the plunger to a signal sensor and processor arranged in communication with a system controller arranged at the upper end of the tubing.

Abstract: An oil-gas vapor collection, storage, and recovery system ensures that no air or oxygen leakage into the production tank occurs when gauging and/or emptying a tank. The system provides a constant reservoir-type storage system by utilizing a variable volume gas bag, expanding with a surge of gas from the separator and with minimal water column pressure from the plunger lift system, thereby containing the gas surge, but contracting with gas dissipation thus minimizing the compressor cycling, while accommodating rapid liquid and vapor influxes into the tank thus maintaining constant tank pressure. With expansion, the bag actuates a switch which activates a compressor, which, in turn, compresses the contained gas into the pipeline. Upon bag collapse, a switch is activated to turn off the compressor. Thus, the system provides constant storage tank pressure because the gas bag accommodates and controls variable gas volume.

Abstract: A method of controlling pressure in a wellbore can include placing a barrier substance in the wellbore while a fluid is present in the wellbore, and flowing another fluid into the wellbore while the first fluid and the barrier substance are in the wellbore. The first and second fluids may have different densities. Another method can include circulating a fluid through a tubular string and an annulus formed between the tubular string and the wellbore, then partially withdrawing the tubular string from the wellbore, then placing a barrier substance in the wellbore, then partially withdrawing the tubular string from the wellbore and then flowing another fluid into the wellbore. A well system can include at least two fluids in a wellbore, the fluids having different densities, and a barrier substance separating the fluids.

Abstract: A method includes performing a chemical process to create a chemical product and an amount of heat, and transferring the heat to a first fluid. The method further includes hydrating a polymer in the first fluid, and adding the chemical product from the chemical process to the first fluid to create a treatment fluid. The method further includes diluting the treatment fluid with respect to at least one constituent of the treatment fluid. The method includes treating a formation of interest in a wellbore with the treatment fluid. The method includes changing a formulation of the treatment fluid during the treating. The method also includes extending the treating beyond a design amount, or ending the treatment before the design amount and preserving some reagents of the chemical process.

Abstract: A technique utilizes a completion system deployed for use in select groundwater applications. The completion system comprises a plurality of sensors, e.g. pressure probes, and a plurality of multi-function tools which are positioned to control the opening and closing of corresponding pumping ports and/or other devices. The multi-function tools can be controlled individually via communication signals, thus avoiding the need to retrieve and/or reconfigure portions of the completion to make operational changes to the pumping ports and/or other devices.

Abstract: A method for the controlled delivery of a fracturing fluid to a well bore comprises formulating an aqueous base fluid such that it meets or exhibits desired physical and chemical characteristics for an optimal fracturing fluid. The formulation of the aqueous base fluid max involve commingling one or more sources of waste water with a source of fresh water followed by controlled injection of one or more additives. This process is substantially completed prior to delivering the aqueous base fluid to the well site. This allows the delivery of an optimal volume of the aqueous base fluid with homogeneously blended additives to the well bore.

Abstract: A control system for use in extracting hydrocarbons from an underground deposit is disclosed that comprises an electromagnetic heating system and a processor. The electromagnetic heating system is configured to heat the underground deposit to facilitate fluid flow of a resource for extraction from the underground deposit. The processor is configured to control the electromagnetic heating system in response to temperature data and pressure data for the underground deposit. The processor correlates the temperature data and pressure data with predetermined water phase characteristics to control the electromagnetic heating system so that substantially all water in the underground deposit is maintained in a liquid state. The control system may also generate voxel data corresponding to spatial characteristics of the underground deposit. The spatial characteristics may be presented as a map on a display.

Abstract: A method includes performing a chemical process to create a chemical product and an amount of heat, and transferring the heat to a first fluid. The method further includes hydrating a polymer in the first fluid, and adding the chemical product from the chemical process to the first fluid to create a treatment fluid. The method further includes diluting the treatment fluid with respect to at least one constituent of the treatment fluid. The method includes treating a formation of interest in a wellbore with the treatment fluid. The method includes changing a formulation of the treatment fluid during the treating. The method also includes extending the treating beyond a design amount, or ending the treatment before the design amount and preserving some reagents of the chemical process.

Abstract: Various embodiments of the present invention disclose enhanced and improved well production tools for increasing the stability of production zones in a wellbore. Various embodiments of the present invention generally relate to apparatuses, systems, and processes for efficiently and effectively isolating zones within a wellbore.

Abstract: A valve assembly employable with a downhole tool configured for conveyance in a wellbore extending into a subterranean formation and method of operating the same. In one embodiment, the valve assembly includes an actuator and a sensing apparatus configured to provide a first signal based on an environment associated with the valve assembly and a second signal based on a characteristic of the valve assembly. The valve assembly also includes a controller configured to provide a third signal to the actuator to alter the characteristic in response to the first and second signals.

Abstract: A method for breaking a fracturing fluid includes identifying application parameter(s) including a subterranean formation temperature, and determining an acid precursor concentration in response to the application parameter(s). The method further includes providing a treatment fluid including a carrier fluid, a metallic peroxide breaker, and an amount of an acid precursor according to the acid precursor concentration, and treating the subterranean formation with the treatment fluid. The application parameter(s) may further include a flowback wait time, a composition of the metallic peroxide breaker, a gel loading of the carrier fluid, and/or a permeability of the subterranean formation. The metallic peroxide breaker may include an alkaline peroxide and/or a zinc peroxide. The acid precursor may include polylactic acid and/or polyglycolic acid.

Abstract: Systems and methods for delivering gases through a single manifold for remediation techniques are described. A system comprises a plurality of gaseous sources and a manifold comprising a plurality of inputs being operable for receiving gases from the gaseous sources, and a plurality of outputs being configured to supply gases to a plurality of injection wells for soil and groundwater remediation. The manifold is further operable for being controlled to select a one of the plurality of inputs and to select a one of the plurality of outputs. A programmable controller is operable for controlling the manifold to select one or more combinations of the plurality of inputs and to select one or more combinations of the plurality of outputs during programmed time intervals.

Abstract: Method and apparatus for handling a supported tubular string with a string elevator and a spider on a rig to prevent damaging contact between the string elevator and spider while facilitating further connections of add-on tubular segments. The string elevator and supported tubular string descend toward the spider until reaching a predetermined position. The process of setting the spider into engagement of the tubular string is automatically initiated in response to detecting the predetermined position of the string elevator. With the spider set, the string elevator can be unloaded. Optionally, the method may also automatically terminate the string elevator descent in response to detecting that the spider has been set. A preferred apparatus for detecting the position of the elevator includes a tilt switch secured to a fixed position along the length of the Kelly hose.

Abstract: A reverse torque drive system for a wellhead has a hydraulic pump having an inlet and an outlet, and a hydraulic motor having a first port and a second port. There is a valve body having a first position that connects the outlet of the hydraulic motor to the first port and the second port to the inlet, and a second position that connects the outlet to the second port and the first port to the inlet. One or more sensors are connected to measure a condition, and a controller moves the valve body from the first position to the second position upon the sensor sensing a predetermined condition.

Abstract: An electrical submersible pump that regulates pump flow rate based on sensor measurements of the fluid is disclosed. The sensor measures a property of the fluid being processed. The sensor may be located at the intake, discharge or other area of the pump. The sensor measures the relative proportion of gas in the pumped liquid. The pump flow rate is adjusted to maintain a desired level for the gas in a production environment. The pump may be used to operate and control a seabed gas-liquid separation and centrifugal pump system.

Abstract: A system for changing a pump displacement configuration includes a blender that provides low-pressure fluid to a pump. The pump has a power end and fluid end, where the fluid end includes a number of plungers. The system includes an actuator that couples the power end with a selectable subset of the plungers. The system further includes a controller that selects a subset of the plungers according to a job pumping rate, a job pumping pressure, and/or a fluid end failure event indicator. The controller further commands the actuator to couple the selected subset of the plungers to the power end.

Abstract: A method and apparatus for controlling a speed of a pump operating in a well. A first step involves monitoring a production flow rate of fluids produced from the well. A second step involves controlling the speed of the pump with reference to the production flow rate by increasing the speed of the pump when the production flow rate is rising and decreasing the speed of the pump when the production flow rate is declining.

Abstract: A method of maintaining a substantially fixed orientation of a pressure control device relative to a movable rig can include rotating a body of the pressure control device while the rig rotates. A method of remotely controlling an orientation of a pressure control device relative to a movable rig can include rotating a body of the pressure control device, and controlling the rotation of the body from a location on the rig remote from the body. A pressure control device for use in conjunction with a rig can include a body, a flange, an orientation device which changes a rotational orientation of the body relative to the flange, and an orientation control system which remotely controls the orientation device.

Abstract: An apparatus for controlling fluid flow that includes a chamber having a first valve and a second valve; a sensor that senses a pressure parameter associated with the chamber; and a controller programmed to operate the first valve and the second valve in response to the sensed pressure parameter may be used to control for flow and to obtain data relating to a formation and/or formation fluid.

Abstract: Method for efficient processing of controlled source electromagnetic data, whereby Maxwell's equations are solved [107] by numerical techniques [109] such as finite difference or finite element in three dimensions for each source location and frequency of interest. The Reciprocity Principle is used [103] to reduce the number of computational source positions, and a multi-grid is used [105] for the computational grid to minimize the total number of cells yet properly treat the source singularity, which is essential to satisfying the conditions required for applicability of the Reciprocity Principle. An initial global resistivity model [101] is Fourier interpolated to the computational multi grids [106]. In inversion embodiments of the invention, Fourier prolongation is used to update [120] the global resistivity model based on optimization results from the multi-grids.

Abstract: This disclosure relates to an apparatus and method for controlling the amount of an additive injected into production fluid in a plurality of production zones. The injection devices may be dynamically controlled such that a central or decentralized control system may instruct a plurality of additive injection assemblies to inject additive, wherein different additive and/or different amounts of additive may be injected in the production fluid in the plurality of production zones. The apparatus includes one or more controllers to send operating commands to downhole regulating elements that may control the amount of additive being injected directly or indirectly.

Abstract: A method of producing fluids from a wellbore that has therein n adjustable flow control device for controlling flow of fluid between a formation and the wellbore may include: providing a tool having a sensor configured to provide measurements relating to a downhole property of interest, wherein the tool is configured to adjust flow from the flow control device; conveying the tool into the wellbore; determining the property of interest using the tool; and adjusting the flow through the flow control device with the tool at least in part in response to the determined parameter of interest. An apparatus for controlling fluid flow between a formation and a wellbore, according to one embodiment may include: a tool configured to be conveyed into a wellbore that contains at least one sensor for estimating a property of interest downhole and a latching device configured to couple to a flow control device in the wellbore to alter flow of the fluid through the flow control device.

Abstract: A process and system for release and recovery of methane from subterranean methane hydrate deposits in which heated CO2 is used to displace methane from the methane hydrate deposits and a portion of the displaced methane is routed to a combustion device proximate the deposit for combustion in-situ, generating heated CO2 which is introduced into the deposit, displacing additional methane, a portion of which is routed to the combustion device, thereby providing a substantially self-sustaining process. Portions of the displace methane not routed to the combustion device are captured for use elsewhere.

Abstract: Systems and methods for the extraction, incineration and monitoring of methane gas extracted from a mine are described herein. In some embodiments, a system includes a transportation platform, a fluid machine coupled to the transportation platform, an incinerator, a vent assembly and a flow interface assembly. The fluid machine is configured to be coupled to a gas well, and to produce a gas flow from the gas well. The incinerator is configured to be fluidically coupled to the fluid machine, and is configured to combust at least a portion of the gas flow from the gas well. The vent assembly is configured to be fluidically coupled to the fluid machine. The flow interface assembly is coupled to the transportation platform and is configured to selectively place the fluid machine in fluid communication with any one of the incinerator and the vent assembly.

Abstract: A gas flow system for removing a liquid from a well bore and allowing for gas production is provided. The gas flow system comprises a casing in the well bore for allowing flow of the liquid and gas; a tubing string in the casing for allowing flow of the liquid and gas; pressure measurement devices for use in determining a rate of liquid influx into the well bore; a casing control valve moveable between various positions ranging from fully open to fully closed for controlling flow through the casing; a tubing control valve moveable between various positions ranging from fully open to fully closed for controlling flow through the tubing; and flow measurement devices for determining the rate of flow through the tubing and the total rate of flow.

Abstract: An improved multi-well control system (MWCS) has a centrally based multi-well controller (MWC) in communication with one or more slave controllers and one or more electronic flow measurement devices (EFMs) for instant data monitoring and control of individual wells. The system also provides for an application host sub-system (AHSS) in communication with the MWC for historical and instant data retention. The system is capable of assigning one or more wells to a group for allocation purposes and organizing groups dependent on production levels of individual wells. The MWC is capable of tracking gas volumes produced by each well independent of groupings and communicating such data to the AHSS. The MWC provides monitoring and tracking data from one or more EFM devices and assigns total flow volume to individual wells. The entire MWCS can result in the reduction of manpower and an increase in overall production efficiency.

Abstract: An Improved Fluid well pumping system and method to produce the system. According to the system, it relates to ones that provide improved, low cost, efficient and low maintenance pumping systems for obtaining fluid from a source. It is envisioned that the systems will be used for removing oil, water, sludge, gaseous fluids, or leachates from shallow to medium depth wells (0 to 4000 feet depths). However, the invention has application for raising any fluids as needed above ground.

Abstract: A method for breaking a fracturing fluid includes identifying application parameter(s) including a subterranean formation temperature, and determining an acid precursor concentration in response to the application parameter(s). The method further includes providing a treatment fluid including a carrier fluid, a metallic peroxide breaker, and an amount of an acid precursor according to the acid precursor concentration, and treating the subterranean formation with the treatment fluid. The application parameter(s) may further include a flowback wait time, a composition of the metallic peroxide breaker, a gel loading of the carrier fluid, and/or a permeability of the subterranean formation. The metallic peroxide breaker may include an alkaline peroxide and/or a zinc peroxide. The acid precursor may include polylactic acid and/or polyglycolic acid.

Abstract: A method includes identifying application parameter(s) including a subterranean formation temperature, determining a breaker particle size in response to the application parameter(s), providing a treatment fluid including a carrier fluid and a granular breaker sized according to the breaker particle size, and treating the subterranean formation with the treatment fluid. The granular breaker is a metallic peroxide which may be an alkaline peroxide and/or zinc peroxide. The application parameter(s) may further include a flowback wait time, a composition of the metallic peroxide, a gel loading of the carrier fluid, and a permeability of the subterranean formation. The breaker particle size may include a breaker large particle size that is not greater than 25% larger than a breaker small particle size. At least 90% of the breaker particles may be sized between the breaker small particle size and the breaker large particle size.

Abstract: Phase-controlled well flow control. A well system includes a flow control device which regulates flow of a fluid in the well system, the flow control device being responsive to both pressure and temperature in the well system to regulate flow of the fluid. A flow control device includes a flow regulator for regulating flow of a fluid through the flow control device, and an actuator which is operative to actuate the flow regulator in response to a predetermined relationship between a phase of the fluid and both pressure and temperature exposed to the actuator. A method of controlling a phase change of a fluid in a well system includes the steps of: flowing the fluid through a flow control device in the well system; and adjusting the flow control device in response to both pressure and temperature in the well system.

Abstract: A screen section has a valve assembly to control flow through it. The valve is open and has a closure spring held compressed by a shape memory material that responds to the presence of a specific well fluid or fluids so that its property changes to allow the spring to deliver the stored potential energy to the valve member to close it when the specific well fluid or fluids are detected. The preferred material is a shape memory polymer that, for example, is sensitive to the presence of water or methane and gets softer to release the potential energy source to operate the downhole tool.

Abstract: A device for liquid removal from a drilled hole equipped for gas production from an underground accumulation, under the conditions in which a downward liquid film flow on the tubing string wall occurs, the device comprising a long lower inner liner (4) whose upper end (b) is beveled, surrounded by an “M”-shaped short-circuiting pipe (7), provided with short vertical portions (j and k), which, at the lower side, are secured to elbows (l and m) of an “M”-shaped discharge path (8) which partially surrounds the lower inner liner, the elbows continuing to the lower side with long vertical portions (n and o) and short vertical portions (p and q) which communicate between them through a lower horizontal portion (r), one long vertical portion having a curved lower end (s) mounted in a window (t) cut into the lower inner liner and the other long vertical portion having an open end (u) located in an accumulation chamber (a).

Abstract: A system for optimizing gravel deposition in a completion interval of a well. The system includes a pumping system that is operable to deliver a gravel pack slurry to the completion interval, an actuator system that is operable to control properties of the gravel pack slurry and a sensor system that is operable to monitor parameters representative of gravel deposition in the completion interval. A dynamic gravel pack model defined in a computer is operable to receive data from the sensor system and provides estimates of gravel deposition in the completion interval. A control system is operable to control the pumping system and the actuator system in relation to a gravel pack deposition plan and the dynamic gravel pack model, wherein the estimates of the dynamic gravel pack model are input into the control system to automatically modify the gravel pack deposition plan.

Abstract: The following invention is an electromechanical system (1) that is to be connected to an electricity supply (7), comprising: an electric machine (2) that can operate as an independent generator with a rotating shaft, and a switching system (9) allowing i) in the first configuration, the electric machine to operate as a motor in the case where the connected device (4) is normally driven or as a generator in the case where the coupled device is normally driving, and ii) in the second configuration, the electric machine to operate as an independent generator, the electrical energy generated by the electric machine (2; 22) being dissipated in the machine and in a dissipative load (13).

Abstract: A system and method for controlling the speed of a progressing cavity liquid well pump to increase liquid production from a well while avoiding operation of the well in a pumped-off state. A controller controls a variable speed drive to drive a progressing cavity liquid well pump at a set pump speed while measuring well and system parameters indicative of pumping performance and/or liquid production from the well. The set speed of the pump is changed in steps either increasingly or decreasingly by the controller, acting through the variable speed drive, in response to the measured well and system parameters. The controller, responsive to the measured well and system parameters, challenges the set pump speed by varying the set pump speed so as to increase the production from the well while avoiding pump and well operation in a pumped-off state.

Abstract: Well bore servicing equipment is provided. The well bore servicing equipment comprises a first manipulator to grip a well bore work string, to raise the work string, and to lower the work string. The well bore servicing equipment further comprises a controller to receive a work string trajectory input and to automatically control the first manipulator to raise and lower the work string substantially in conformance with the work string trajectory input.

Abstract: Well bore servicing equipment is provided. The well bore servicing equipment comprises a first manipulator to grip a well bore work string, to raise the work string, and to lower the work string. The well bore servicing equipment further comprises a controller to receive a work string trajectory input and to automatically control the first manipulator to raise and lower the work string substantially in conformance with the work string trajectory input.

Abstract: A method for breaking a fracturing fluid includes identifying application parameter(s) including a subterranean formation temperature, and determining an acid precursor concentration in response to the application parameter(s). The method further includes providing a treatment fluid including a carrier fluid, a metallic peroxide breaker, and an amount of an acid precursor according to the acid precursor concentration, and treating the subterranean formation with the treatment fluid. The application parameter(s) may further include a flowback wait time, a composition of the metallic peroxide breaker, a gel loading of the carrier fluid, and/or a permeability of the subterranean formation. The metallic peroxide breaker may include an alkaline peroxide and/or a zinc peroxide. The acid precursor may include polylactic acid and/or polyglycolic acid.

Abstract: Well bore servicing equipment is provided. The well bore servicing equipment comprises a first manipulator to grip a well bore work string, to raise the work string, and to lower the work string. The well bore servicing equipment further comprises a controller to receive a work string trajectory input and to automatically control the first manipulator to raise and lower the work string substantially in conformance with the work string trajectory input.

Abstract: A technique facilitates monitoring of conditions which are prone to cause scale precipitation around downhole equipment. The technique also enables a local, downhole reaction to the potential for precipitation of scale. A downhole scale monitoring and inhibition system may be provided with a measurement module and injection module. The measurement module monitors at least one downhole parameter indicative of the potential for scale formation. In response to data output from the measurement module, the injection module is operated to provide downhole, local injections of an inhibitor chemical.

Abstract: A wellbore shut-off valve is operably associated with a valve actuator so that the shut-off valve can be selectively moved between open and closed conditions when desired rather than opening and closing occurring automatically as portions of the production assembly are removed or replaced in the wellbore.

Abstract: Well bore servicing equipment is provided. The well bore servicing equipment comprises a first manipulator to grip a well bore work string, to raise the work string, and to lower the work string. The well bore servicing equipment further comprises a controller to receive a work string trajectory input and to automatically control the first manipulator to raise and lower the work string substantially in conformance with the work string trajectory input.

Abstract: A method and apparatus for controlling the production of well treatment fluid is disclosed. The apparatus includes: a sand system, a water system, a pumping system, a blender tub, and a virtual rate control system. The method includes determining an output rate from a sand system; sensing an output rate from a water system; sensing an output rate from a pumping system; sensing the height within a blender tub of a mixture of sand from the sand system and water from the water system; providing a virtual rate control system; and producing a drive signal to the pumping system using the virtual rate control system using a desired rate of well treatment fluid to be delivered to a well, the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system.

Abstract: The present invention generally relates to the control of fluid flow in a wellbore. In one aspect, a flow control device for use in a wellbore is provided. The flow control device includes an inner member having at least one aperture formed therein. The flow control device also includes an outer member disposed around the inner member such that a flow path is defined between the inner member and the outer member. Additionally, the flow control device includes an elastomer member disposed within the outer member adjacent a portion of the flow path, wherein the elastomer member is capable of swelling upon contact with an actuating agent. In another aspect, a method of controlling fluid flow in a wellbore is provided. In yet a further aspect, an apparatus for controlling the flow of fluid in a wellbore is provided.

Abstract: A bottom hole assembly is run into the wellbore on slickline with a tractor to assist in movement of the bottom hole assembly through a deviation in either direction. The tractor can have retractable drive components and can be responsive to tension in the slickline to turn it on and to avoid overrunning the slickline if driving out.

Abstract: A well system is provided and configured for local and/or global control of a well. The well system may comprise one or more controllable downhole devices. Each of the downhole devices may include a telemetry module, an energy module configured to at least power an actuator, a controller communicably coupled to the telemetry module and one or more sensors, and a controllable component coupled to the actuator. The well system may further include a surface controller comprising a desired state input device configured to accept a desired state and then provide the desired state to the controller via the telemetry module. The controller may compare the desired state to an actual state determined by a sensor and instruct the actuator to adjust the controllable component such that the actual state approaches the desired state. The downhole device may operate autonomously after the initial setting of the desired state.

Abstract: Methods for determining whether to perform a stimulation treatment on a subterranean zone are disclosed. Process zone stress (“PZS”), indicative of a production potential of the subterranean zone, is determined, and a determination is made as to whether the PZS exceeds a preselected value. A PZS exceeding the preselected value may indicate a poor production potential, and a stimulation treatment of the subterranean zone may be avoided. As a result, a substantial cost saving associated with the avoided stimulation treatment may be realized.

Abstract: A transmitter generates an acoustic ping in a fluid in a borehole, and a receiver monitors waves resulting from the acoustic ping. Responsive to the monitored waves, an attribute of the fluid is estimated, including a sonic velocity, a mixture of gas and oil, a mixture of water and oil, an amount of sand, an amount of gas, an amount of skin effect, or a depth of fluid. An operation of the artificial lift device is then controlled responsive to the estimated attribute. Alternately, a sonic velocity is estimated for the fluid through an analysis of a sample pumped to the surface or through an analysis of monitored waves. A depth of the fluid is calculated responsive to the estimated sonic velocity for the fluid in the borehole and the monitored T-waves. The operation of the artificial lift device is then controlled responsive to the calculated depth of fluid.

Abstract: Some embodiments include a heavy-oil-based hydrocarbons effluent production installation for the production of hydrocarbons from at least one well. The installation includes an effluent-lightening fluid injection system at the bottom of the well, an effluent-evacuation pump, a plurality of sensors that measure physical units relating to the installation, and an automated device suitable for optimizing the lightening-fluid injection flow-rate and for regulating the pump speed. The automated device regulates the pump speed according to the physical units and a predetermined target production value. The speed of the pump and the physical units are within a predetermined range of values. some embodiments include a hydrocarbons production method in such an installation. Some embodiments make it possible to ensure a minimum consumption of lightening fluid, while ensuring good operation of the pump and good productivity of the well.

Abstract: A system and method for releasing a marker within a wellbore is provided. The system and method includes a sensor that detects movement or a position of the marker within the wellbore. The marker may be released in drilling fluid, for example, and may travel from the surface to the drill bit and return to the surface with cuttings. As an example, the markers are used to determine the flow of cuttings within the wellbore.