Abstract: A mud pulse telemetry tool is used in a drill string that has a drilling fluid flowing inside. The mud pulse telemetry tool may include a pulser disposed in the drill string and a drive system for driving the pulser. The pulser may include a non-rotating mud pulse stator and a mud pulse rotor disposed proximate to the stator. The drive system may include a turbine stator, a turbine rotor, and a rotatable inertial member magnetically coupled to the turbine rotor. The inertial member may be operatively connected at a first end to the mud pulse rotor. In the mud pulse telemetry tool, rotational energy may be transmitted from the turbine rotor to the rotatable inertial member by a magnetic coupling. The rotatable inertial member may be operatively connected to a supplemental motor that is adapted to supplement rotational energy imparted to the rotatable inertial member by the drive system.

Abstract: A method for estimating a steady state response of a drill string in a borehole includes calculating a first displacement of the drill string in a frequency domain for a first excitation force frequency and a number of multiples of this frequency using an equation of motion of the drill string. The equation of motion has a static force component, an excitation force component, and a non-linear force component with respect to at least one of a deflection and a derivative of the deflection of the drill string. The method further includes: transforming the first displacement from the frequency domain into a time domain; calculating a non-linear force in the time domain; calculating a frequency domain coefficient derived from the calculated non-linear force in the time domain; and calculating a second displacement of the drill string in the frequency domain using the equation of motion and the frequency domain coefficient.

Abstract: Remote operation of downhole tools in a subterranean wellbore is performed by inserting untethered, mobile devices sequentially into the wellbore. The mobile devices can include motive means, power supply, communication and data storage means, etc. In one embodiment, the method comprises maneuvering a first mobile device into proximity with a downhole tool, the device powering the tool. The first device is then removed, such as by flowing up or dissolving. The now-powered tool is used to perform a test or other operation. A second mobile device is maneuvered into proximity with the downhole tool and data is transferred. The second device is retrieved with the data or, using on-board logic devices, provides “if-then” commands to the downhole tool. Alternately, a third mobile device can be used to power and transfer commands to the tool. The method can be used for various tasks, such as opening bypass ports on ICD valves.

Abstract: A subsea communication system is used to communicate between a position that is proximal to a surface of the sea and an apparatus of the seabed. The subsea communication system includes an umbilicalless communication system.

Abstract: This disclosure relates to determining optimal parameters for a downhole operation. In a general aspect, a computer-implemented method for managing a downhole operation is described in this disclosure. The method includes receiving a continuous stream of real-time data associated with an ongoing downhole operation at a data ware house. In the meantime, a selection of a downhole parameter is received from a user. Then, with a computing system, the selected downhole parameter is optimized based on a portion of the received stream of data to approach a target value of the selected downhole parameter. The optimized downhole parameter can then be used in the ongoing operation.

Abstract: A system for remote control of operation control elements that are arranged in a well to control recovery of gas and/or oil from the well. A first system part is located outside the well and connected to a second system part that is located in the well and operatively connected to the operation control elements. All semiconductor components are housed in the first system part. The second system part houses electromechanical components that actuate the operation control elements upon command from the first system part. A method for remote control of down-hole operation control elements in an oil and/or a gas well completion. A first system part located outside the well is equipped with all semiconductor components that are included in the system. A second down-hole system part is equipped with electromechanical components that are actuated from the first system part for actuation of the operation control elements.

Abstract: A downlinking signal is transmitted downhole from the surface using drilling fluid as the communications medium. The downlinking signal includes at least a synchronization phase and a command phase. The downlinking signal is differentiated upon reception such that attributes of the synchronization phase may be used to determine corresponding attributes of the command phase. Commands may be transmitted downhole while drilling and simultaneously while using mud-pulse telemetry uplinking techniques.

Abstract: Apparatus and associated methods may relate to a sensor controller configured to apply predetermined criteria to determine when a parameter value sampled by a sensor module meets the predetermined criteria, and in response to making such a determination, adjust a commanded data rate including an update time period. In an illustrative example, the predetermined criteria may be independently defined for each sensor in a network. In examples with a network of sensors, the sensor controller may dictate sensor module operation at differentiated data rates. In an illustrative example, a sensor controller may communicate with a series of pressure level sensor modules connected to a drilling apparatus in a mud logging application. Upon detection of a pressure level change that exceeds a critical condition as determined through comparison with the predetermined criteria, the sensor controller may increase or decrease a data rate of the respective sensor module, for example.

Abstract: A production shutdown system for an underwater hydrocarbon production facility, comprising, on the topside: a safety system, and a communications module; and, underwater; drive control means, and an underwater communications component; wherein in use safety signals are passed from the safety system to the drive control means via the topside communications module and the underwater communications component, and wherein the safety system and drive control means are rated according to a prescribed safety level but the communications module and underwater communications component are not so rated.

Abstract: A method for removing cyclic noise from a borehole image includes transforming the image into the frequency domain using a two-dimensional (2-D) Fourier Transform, removing cyclic noise components from the transformed image, and inverse transforming the image back into the spatial domain using an inverse 2-D Fourier Transform. The cyclic noise component may also be isolated by subtracting the corrected image from the original image or by removing all non-cyclic noise components from the transformed image prior to inverse transforming. Removal of the cyclic noise from a borehole image tends to enable the identification of borehole features and provide for improved accuracy in formation parameter evaluation. Evaluation of the cyclic noise component may also enable the source of the noise to be identified and mitigated.

Abstract: A system and a method manage and use data related to a wellbore or a drill string. The system and the method may provide remote access to tools in a drill string using a network. In addition, the tools have access to the data. In a disclosed embodiment, the tools are able to automatically access the data needed to optimize or improve function of the tools. An example of the network is a wireless network where the tools may be monitored and/or controlled remotely by an application. A linking tool is optionally provided to communicate with the network and one or more of the tools.

Abstract: A system for communication in an oil and gas well, the system including a controller, a first universal wireless adapter (UWA) wirelessly coupled to the controller, where the UWA is coupled to a first field device, a second UWA wirelessly coupled to the controller, where the UWA is coupled to a second field device, where the controller passes a control token among the first and second UWAs based upon communication traffic between the first and second UWA and the first and second field devices respectively. In some embodiments, this control token may be passed between the first and second UWAs depending upon communications between the respective UWAs and their field devices. For example, in the event that communication traffic is greater between the first UWA and the first field device, then the control token is passed to the first UWA.

Abstract: A method of servicing a wellbore is provided. The method comprises establishing a communication link between a wellsite and a central control site, wherein the communication link carries sensor, audio, and video data to the central control site and carries command parameters to the wellsite to command wellbore servicing equipment on the wellsite. The data transmitted by the wellsite is analyzed at the central control site, stored in a data store at the central control site, and the results of analysis displayed on a display at the central control site.

Abstract: A downlinking signal is transmitted downhole from the surface using drilling fluid as the communications medium. The downlinking signal includes at least a synchronization phase and a command phase. Attributes of the synchronization phase are used upon reception of the signal to determine corresponding attributes of the command phase. Commands may be transmitted downhole while drilling and simultaneously while using mud-pulse telemetry uplinking techniques.

Abstract: Remote operation of downhole tools in a subterranean wellbore is performed by inserting untethered, mobile devices sequentially into the wellbore. The mobile devices can include motive means, power supply, communication and data storage means, etc. In one embodiment, the method comprises maneuvering a first mobile device into proximity with a downhole tool, the device powering the tool. The first device is then removed, such as by flowing up or dissolving. The now-powered tool is used to perform a test or other operation. A second mobile device is maneuvered into proximity with the downhole tool and data is transferred. The second device is retrieved with the data or, using on-board logic devices, provides “if-then” commands to the downhole tool. Alternately, a third mobile device can be used to power and transfer commands to the tool. The method can be used for various tasks, such as opening bypass ports on ICD valves.

Abstract: An electronic module for use as a subsea electronic module for an underwater fluid extraction well, wherein a local area network enables communication within the module, the local area network including a plurality of interfaces with components of the network, and wherein the interfaces comprise capacitive coupling interfaces.

Abstract: A downhole tool system includes a first downhole tool and a second downhole tool. The first downhole tool includes a first controller operable to receive an actuation signal including a tone. The first controller actuates the first downhole tool if the tone is a first specified frequency and changes the first downhole tool to communicate the actuation signal to the second downhole tool if first downhole tool is not actuated in response to the actuation signal. A second downhole tool includes a second controller operable to receive the actuation signal. The second controller actuates the second downhole tool if the tone is a second specified frequency. The second frequency is different from the first frequency.

Abstract: A downhole tool system includes a first downhole tool and a second downhole tool. The first downhole tool includes a first controller operable to receive an actuation signal including a tone. The first controller actuates the first downhole tool if the tone is a first specified frequency and changes the first downhole tool to communicate the actuation signal to the second downhole tool if first downhole tool is not actuated in response to the actuation signal. A second downhole tool includes a second controller operable to receive the actuation signal. The second controller actuates the second downhole tool if the tone is a second specified frequency. The second frequency is different from the first frequency.

Abstract: A telemetry system for use in developing a field of wells has a first downhole device capable of transmitting and/or receiving signals disposed in an appraisal well, an electronics control system located at or near the top of the appraisal, a cable disposed in the appraisal well that provides signal communication between the first downhole device and the electronics control system, and a second downhole device capable of transmitting and/or receiving signals disposed in a second wellbore. The signal is passed through the cable between the first downhole device and the electronics control system. From there, the signal may be re-transmitted to a desired location.

Abstract: The present disclosure includes an apparatus and method for operating a downhole tool in a borehole. The apparatus may include a downhole tool that may include at least one second clock, which may be synchronized to a first clock by way of a modulator/demodulator device. The downhole tool may be configured to estimate a parameter of interest of an underground feature. The underground feature may relate to one or more of: a borehole, a casing, or an earth formation. The downhole tool may comprise two or more sections that are configured to operate synchronously when the one or more second clocks are synchronized with the first clock. The modulator/demodulator may include a modem associated with the first clock, a modem associated with the at least one second clock, and a low frequency conductor between the two modems. The method includes using the apparatus.

Abstract: A system for directing the drilling of a well at a drill-site includes an instructing unit, an instructed unit, and a central unit. The instructed unit receives drilling instruction from an instructing driller, sends drilling instructions to the central unit, and presents to the instructing driller drilling instructions and instruction confirmations received from the central unit. The instructed unit receives instruction confirmations from an instructed driller, sends instruction confirmations to the central unit, and presents to the instructed driller drilling instructions received from the central unit. The central unit stores and forwards drilling instructions and instruction confirmations to the instructing unit and instructed unit, and generates and stores slide sheet information from the drilling instructions.

Abstract: Identification and tracking of hollow pipes at a site where the hollow pipes are to be stored or interconnected, such as an oil drilling site where the aforesaid hollow pipes are to be connected and the drillstring of pipes is to be inserted into a drilled hole on solid ground or under a deepsea drilling platform is achieved. Each hollow pipe is provided with a low frequency radio frequency identification (RFID) tag attached to the pipe's outer surface. The RFID tag is operable at a low radio frequency not exceeding 1.0 megahertz and may be disposed within a recess in the pipe's outer surface. A tracking system provides communication be the tags and a reader.

Abstract: A module for use as a subsea electronic module of a subsea well, comprises an input (7) for receiving signals from a sensor arrangement which senses at least one parameter of a well, the module including a plurality of separate, different electronic circuits (9), each of which is selectable to be in communication with said input and each of which is adapted to co-operate with a respective, different form of such a sensor arrangement.

Abstract: This assembly includes a measuring device (50) including a container (60) and an insert (62) arranged in the container (60). The measuring device (50) includes a means (68) for driving the container (60) in rotation around a central axis, the container (60) and the insert (62) defining an intermediate space (64) between them for measuring the drilling fluid. The assembly includes a control and measurement unit (58), capable of recording information representative of the force applied by the drilling fluid on the insert (62) during the rotation of the container (60). The assembly includes an intake pipe (84) for bringing drilling fluid to be measured into the intermediate space (94) and a pump (82), comprising an inlet connected to a sampling head (80) and an outlet connected to the intake pipe (84) to pump the drilling fluid towards the intermediate space (64).

Abstract: Mud pulse telemetry systems and methods that employ some combination of modulated pulse positions, modulated pulse widths, and modulated pulse amplitudes to increase telemetry data rates. In at least some of the employed coding techniques, information is conveyed by the positions of both the upward and downward transitions. In some embodiments, fixed symbol intervals are used to convey combinatorial coded waveforms. In other embodiments, variable length symbol intervals include both a pulse position interval and a pulse width interval. The two intervals can be independently varied to convey telemetry data. Subject to specific system constraints, optimal coding efficiencies may be expected at data rates of between four and seven bits per symbol interval.

Abstract: Apparatus and systems, as well as methods, operate to acquire downhole data associated with a borehole casing, process a portion of the downhole data at a downhole location to provide processed data, and regulate surface motor power received at a motor downhole. The surface motor power is filtered and the processed data is transmitted to a surface location on a monoconductor that also carries the surface motor power. Additional apparatus, systems, and methods are disclosed.

Abstract: The well test system has a net oil computer NOC that captures and stores information from disparate well instrumentation devices, measures produced oil, water, and gas quantities based on the information and controls well processes based on the quantity measurements. The NOC includes operational software that collects instrumentation data from a plurality of wells. Configuration software downloads user programmable configuration information to the NOC, which enables the NOC to record data from a wide variety of flow devices, water test meters, or the like. User programmable alarms are included. A plurality of controllers can control processes associated with individual wells. A wireless communication system electronically sends data and test results to cell phones, radio devices, and the like. A daily test data log provides a historical database, which is analyzed to formulate “Data Confidence” information for each well. The net oil computer is operable with two-phase or three-phase separators.

Abstract: A measurement-while-drilling mud pulser and a method for controlling a measurement-while-drilling mud pulser. The mud pulser includes a brushless DC motor that hydraulically controls a main restrictor valve that the mud pulser uses to generate mud pulses. Back EMF signals generated in the stator windings of the brushless DC motor are monitored and are used as the basis for commutating the brushless DC motor. The phase transitions in the back EMF signals can be used in governing stator energizations of the brushless DC motor to thereby govern its rotation. Relying on back EMF signals for commutation allows commutation to be performed without Hall Effect or other kinds of sensors, which can thereby reduce cost of the mud pulser and further increase reliability of the mud pulser by decreasing the number of high pressure sealings needed due to wires from Hall effect sensors, which are prone to develop leaks.

Abstract: O-ring or other fluid seal member (10) and method of making such member. The member has a body (12) provided as a preform of a curable elastomeric polymeric material. A radio frequency identification (RFID) transponder (50) is inserted into the preform. The preform is then cured to form the body and to embed the RFID transponder (50) therein.

Abstract: A system and method for communicating with a downhole tool is disclosed. In one embodiment, a telemetry system for communicating with a downhole tool in a wellbore includes a first electrode. A modulated electric current flows from the first electrode through a formation to the downhole tool. The telemetry system also includes a downlink box, which provides the modulated electric current to the first electrode. The downhole tool comprises a sensor unit, which detects the modulated electric current. The telemetry system includes a second electrode that allows the modulated electric current to return to the downlink box. The telemetry system also includes an uplink telemetry, wherein the uplink telemetry does not comprise electromagnetic telemetry. In some embodiments, the downlink may be operated while mud pumps are turned off. The downlink may also be operated while the downhole tool is sending uplink telemetry by a method other than electromagnetic current.

Abstract: A system and method for communicating data between a downhole tool and a surface controller is provided that comprises a rotating drill string extending in a borehole and having a downhole telemetry module disposed proximate a bottom end thereof and transmitting a first signal across a telemetry channel. A surface telemetry module is disposed proximate a top end of the rotating drill string and is adapted to receive the first signal transmitted by the downhole telemetry module across the transmission channel. The surface telemetry module has a radio frequency transmitter disposed therein for transmitting a second signal related to the first signal. A stationary communication module has a radio frequency receiver adapted to receive the second signal.

Abstract: In one aspect of the present invention, a method for tool string communication comprises the steps of providing a downhole tool string with at least two downhole LWD/MWD instruments in electrical communication with a downhole telemetry system. The instruments are capable of generating at least one data packet assigned a priority. The tool string is deployed in a wellbore and then the priority of the data packet is changed.

Abstract: A method for communicating with a receiver during an electromagnetic survey. In one implementation, the method may include sending a survey signal to a subsurface region, wherein the survey signals is a first electromagnetic signal and sending a diagnostic signal to the receiver. The diagnostic signal is a second electromagnetic signal having a diagnostic message.

Abstract: A system for enabling communication between an underwater fluid extraction facility and a remote location comprises a fiber-optic cable connected between the facility to the remote location, signal transmission means at the remote location for transmitting signals to the fiber-optic cable, a distribution hub for receiving signals from the other end of the cable and at least one secondary hub located at the facility in communication with the distribution hub. Communication between the facility and the remote location is effected using a Local Area Network. Preferably Ethernet signalling is used throughout the network.

Abstract: A method for downhole communication and an apparatus for remote actuation of a downhole tool is disclosed. The method comprises the steps of: programming at least one tag (20) to emit a radio frequency identification signal in the form of a frequency change in a carrier wave; locating a reader (10) responsive to signals emitted from the at least one tag downhole; moving the at least one tag (20) past the downhole reader (10) such that the downhole reader (10) is capable of reading data from the tag (20) when the tag (20) passes the reader (10); and thereby communicating data from the tag (20) to the reader (10) downhole. Typically, the method includes programming the tag (20) and the reader (10) to communicate data by at least one of the following means: transitions between discrete frequencies; use of specific discrete frequencies; and length of time in which a carrier wave emits a specific frequency in preference to at least one other frequency.

Abstract: Systems and methods for downhole completions. A downhole running tool can have a body having a bore formed therethrough. A latch member can be disposed on a first portion of the body. A reset member can be disposed on a second portion of the body. A conduit can be formed within a sidewall of the body. The conduit can be located between the first and second portions of the body. A pressure relief port can be disposed at a first end of the conduit; and a first flow port can be disposed at a second end of the conduit. The pressure relief port and first flow port can be in communication with an outer diameter of the body.

Abstract: A pollution information message system provides a system and method for generating and transmitting pollution information messages. In one embodiment, the pollution information message system employs a transceiver network with a plurality transceivers coupled to monitoring devices. Control room operators receive a pollution information message from an identifiable transceiver. The transceiver, identified by an identification code, indicates a location and the nature of the detected pollution. Other aspects, embodiments, and features are also claimed and described.

Abstract: A method is provided which transmits information using a plurality of data transmission nodes situated along a drill string. In this method, a first node obtains a transmission status of a second node. When the transmission status of the second node indicates that the second node meets a selected performance threshold, information is sent from the first node to the second node. When the transmission status of the second node indicates that the second node does not meet its performance threshold, then the first node obtains a transmission status of a third node. When the transmission status of the third node indicates that the third node meets a selected performance threshold, information is transmitted from the first node to the third node for relaying along the drill string.

Abstract: The present invention describes a system for accurately measuring the concentration of a substance within a filter housing. A concentration sensor and a communications device are coupled so as to measure and transmit the concentration of a particular substance within the filter housing while in use. This system allows the operator to certify the integrity of the filters within the filter housing at the customer site without additional equipment. In one embodiment, a tracer gas, such as helium or hydrogen, is added to a carrier and injected into the system. The concentration of tracer gas at a specific operating transmembrane pressure is indicative of bubble pointing specific pores in the filter. This test will give a more sensitive indication of the bubble point and the presence of defects than a standard diffusion test. In a second embodiment, two gasses, in a known ratio, are introduced into the filter housing.

Abstract: An apparatus and method are disclosed for sensing a characteristic of a borehole. An exemplary apparatus includes a conductive pipe; an inlet, connected to the conductive pipe, for applying pulse to the conductive pipe; a resonant network device connected with the conductive pipe; and a transducer which is in operative communication with the resonant network device to measure a borehole characteristic, the transducer being configured to sense a modulated vibration frequency induced in the resonant network device when a pulse is applied to the inlet.

Abstract: Systems, program product, and methods for providing real-time reservoir management of one or more reservoirs across one or more fields are provided. A system can include multiple monitoring wells and at least one injection well in communication with a central facility including a reservoir management computer or server positioned to provide real-time reservoir management of the one or more reservoirs. The computer can include, stored in memory, reservoir management program code, which when executed, can cause the computer to perform the operations of calibrating an injection well model for each of one or more injection wells positioned in a reservoir responsive to real-time injection rate and wellhead pressure data associated therewith, calculating static reservoir pressure for each of the injection wells responsive to the respective calibrated injection well model and responsive to respective surface injection rate and wellhead pressure data, and generating real-time automated isobaric pressure maps.

Abstract: A method for analyzing an oilfield network. The method includes collecting oilfield data from an oilfield network, modeling a first wellsite and a second wellsite using the oilfield data to create a first production model of the first wellsite and a second production model of the second wellsite. The method further includes modeling a sub-network of the oilfield network to create a third production model of the sub-network. The modeling of the sub-network includes identifying a junction of branches associated with the first wellsite and the second wellsite. A fourth production model is created for the junction by combining the first production model with the second production model. The production model of the sub-network is created using the fourth production model of the junction. The method further includes solving the oilfield network based on the third production model to create a production result, and storing the production result.

Abstract: A method to detect the relative position of a drill bit with respect to a coal seam boundary using an electric-field borehole telemetry apparatus, that includes the steps: providing a measure-while-drilling apparatus that includes inclination sensors, directional sensors, logging sensors of choice and an electric-field borehole telemetry apparatus, within the electric-field borehole telemetry apparatus, in addition to monitoring the inclination, direction and logging parameters, monitoring one or more parameters of the electrical output of the telemetry apparatus, transmitting to the surface the inclination, direction and logging parameters as well as the one or more parameters of the electrical output by means of the telemetry apparatus, computing the usual drilling parameters needed to guide the drill string along the intended path, determining from the one or more transmitted parameters of the electrical output from the downhole apparatus parameters indicative of approaching or penetrating the coal boundar

Abstract: A logging system for use in a wellbore formed in an earth formation. A tubular conduit is provided extending from surface into the wellbore, as well as a surface communication and control device located at the surface. A telemetry device located inside the wellbore is capable of sending and receiving signals to and/or from the surface communication and control device, the signals representing commands and/or data. Also provided is a logging tool string that is capable of passing from a position within the conduit to a position outside the conduit at a lower end part thereof and capable of being suspended by the conduit in said position outside the conduit. Communication of the commands and/or data between the logging tool string and the telemetry device is established using a communication interface between the logging tool string and the telemetry device.

Abstract: Apparatuses and methods to power and communicate with downhole sensors are presented. Preferred embodiments of the present invention includes energizing a downhole sensor with a surface pressure wave generator and a downhole mechanical to electrical energy converter. Preferred embodiments of the present invention also include transmitting data measured from a downhole sensor to a surface unit through modulation of surface-generated pressure waves.

Abstract: A method and apparatus for controlling oil well drilling equipment is disclosed. One or more sensors are distributed in the oil well drilling equipment. Each sensor produces a signal. A surface processor coupled to the one or more sensors via a high speed communications medium receives the signals from the one or more sensors via the high speed communications medium. The surface processor is situated on or near the earth's surface. The surface processor includes a program to process the received signals and to produce one or more control signals. The system includes one or more controllable elements distributed in the oil well drilling equipment. The one or more controllable elements respond to the one or more control signals.

Abstract: A method of servicing a wellbore, comprising placing a plurality of Micro-Electro-Mechanical System (MEMS) sensors in a wellbore composition, placing the wellbore composition in the wellbore, and obtaining data from the MEMS sensors using a plurality of data interrogation units spaced along a length of the wellbore. A method of servicing a wellbore, comprising placing a plurality of Micro-Electro-Mechanical System (MEMS) sensors in a wellbore composition, placing the wellbore composition in the wellbore, forming a network comprising the MEMS sensors, and transferring data obtained by the MEMS sensors from an interior of the wellbore to an exterior of the wellbore via the network.

Abstract: A data communication system for use in downhole applications wherein electrical energy is supplied over a multiple-conductor power cable to an ESP motor assembly. A downhole unit is AC-coupled to the conductors of the power cable through the wye point of the ESP motor assembly. A surface unit is AC-coupled to the conductors of the power cable. Uplink communication of telemetry data occurs over an AC communication scheme supported by the downhole unit and the surface unit. Downlink communication of remote control command data occurs over a different AC communication scheme supported by the surface unit and the downhole unit. These AC communication schemes provide an independent supply of power to the downhole environment. All communication between the surface and downhole environment is accomplished through the power cable without the use of additional communication lines. Data communication is maintained in the event of a ground fault on the power cable.

Abstract: A method for monitoring a Christmas tree assembly installed on a subsea hydrocarbon well includes receiving a plurality of parameters associated with the Christmas tree assembly. A health metric for the Christmas tree assembly is determined based on the parameters. A problem condition with the Christmas tree assembly is identified based on the determined health metric.

Abstract: A method for taking seismic measurements that includes a downhole sensor positionable within a tool string located within the bore of a well, the tool string having a network which effects communication with a downhole sensor. The downhole sensor includes a downhole clock that may be placed in communication over the network with the top-hole clock for synchronization. A seismic source is positioned within a transmitting distance of the downhole sensor and activated at a time when the network is disconnected. The downhole sensor records signals from the seismic source at along with a downhole timestamp from the downhole clock. When the network is reconnected, the downhole clock and the top-hole clock are re-synchronized and any downhole clock drift is calculated. The recorded downhole timestamp may then be adjusted to reflect what it would have been if the downhole clock had been synchronized with the top-hole clock.