Abstract: This invention relates in general to measuring depth of well-tools, such as logging tools or the like, in a borehole. Embodiments of the present invention may provide for disposing transponders along a wireline that may be used to suspend and move the well-tool in the borehole, where the transponders may be disposed along the wireline at predetermined locations. A reader may be located at a reference location and may read when a transponder passes through the reference location and this information may be used to determine the depth of the well-tool in the borehole. Additionally, this invention provides for combining depth measurements from the transponders with measurements from odometer wheels in frictional contact with the wireline and/or time of flight measurements of optical pulses passed along a fiber optic cable coupled with the wireline to accurately and robustly measure the depth of the wireline in the borehole.

Abstract: A method for performing operations and for improving production in a well includes the steps of: providing radio identification devices at known locations in the well, and providing a reader device configured to read the identification devices, and to control the operations responsive to signals from the identification devices. The method also includes the steps of providing a process tool, and transporting the process tool and the reader device through the well. The reader device is programmed to control the process tool upon reception of a response signal from a selected identification device. The method can be used to perform perforating processes, packer setting processes, bridge plug setting processes, logging processes, inspection processes, chemical treating processes, and cleaning processes. In addition, the method can be performed dynamically by controlling the tool as it moves through the well, or statically by stopping the tool at a particular location within the well.

Abstract: Disclosed herein is a surface controlled subsurface safety valve (SCSSV) that includes a moveable component of the SCSSV and a stationary component of the SCSSV. A sensor element is also included which is configured to sense position of the moveable component relative to the stationary component. Further disclosed herein is a method for sensing position of an object which includes placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component and causing a stress on the material with the separate component. The method further includes measuring a change in magnetic permeability of the material.

Abstract: A treatment apparatus and method for wellbore instability is described including a caliper with one or more radially extending arms which are capable of extending and retracting movement in a radial direction and a fluid supply facility to deliver treatment fluid from the ends of the arms to the wellbore wall, with a sensing and valve mechanism such that in use fluid is being delivered from the end of any extended arm to a breakout region of the wellbore where there is instability.

Abstract: This invention relates in general to measuring depth of well-tools, such as logging tools or the like, in a borehole. Embodiments of the present invention may provide for disposing conducting areas along a wireline that may be used to suspend and move the well-tool in the borehole, where the conducting areas may be disposed along the wireline at predetermined locations. A reader may be located at a reference location and may read when a conducting area passes through the reference location and this information may be used to determine the depth of the well-tool in the borehole. Additionally, this invention provides for combining depth measurements from the conducting areas with measurements from odometer wheels in frictional contact with the wireline and/or time of flight measurements of optical pulses passed along a fiber optic cable coupled with the wireline to accurately and robustly measure the depth of the wireline in the borehole.

Abstract: A perimetrically acting collet includes a body and at least one mating profile opening in the body. A plurality of resilient members located adjacent one side of the at least one mating profile opening and a profiled body is biased perimetrically by the plurality of resilient members.

Abstract: A method for estimating an azimuthal dependence of a parameter of a borehole using logging sensor measurements acquired as a function of azimuth of the logging sensors is provided. The method includes acquiring at least one logging sensor measurement and a corresponding azimuth from a downhole tool. The method further includes processing a convolution of the logging sensor measurement and corresponding azimuth with a predetermined filter to determine convolved logging sensor data for at least one azimuthal position. Certain embodiments of this invention may be advantageously utilized in LWD imaging applications to provide for superior image resolution and noise rejection as compared to prior art imaging techniques.

Abstract: A method for performing operations and for improving production in a well includes the steps of: providing radio identification devices at known locations in the well, and providing a reader device configured to read the identification devices, and to control the operations responsive to signals from the identification devices. The method also includes the steps of providing a process tool, and transporting the process tool and the reader device through the well. The reader device is programmed to control the process tool upon reception of a response signal from a selected identification device. The method can be used to perform perforating processes, packer setting processes, bridge plug setting processes, logging processes, inspection processes, chemical treating processes, and cleaning processes. In addition, the method can be performed dynamically by controlling the tool as it moves through the well, or statically by stopping the tool at a particular location within the well.

Abstract: Disclosed is a method of utilizing a pressure signature in conjunction with a plunger's fall time as an indicator of plunger location. The disclosed method can also indicate well and/or plunger conditions. A controller that can see and interpret slope change and/or pressure signature and automatically make changes to plunger fall time is also disclosed.

Abstract: This invention provides a method for determining the size of tubular pipe to be inserted into an interval of cased or uncased borehole, comprising: determining the position of the borehole wall or innermost casing surface in the interval; defining a window length that is less than the length of the interval and defining a series of windows along the interval; for each window, using the determined position of the borehole wall in that window to define a polygon, the circumference of which is defined by the parts of the borehole wall closest to the borehole axis in that window; determining the maximum size of pipe diameter that will fit inside the polygon in each window without intersecting the circumference; selecting the size of pipe to be inserted into the interval based on the maximum size of diameter pipe determined for each window.

Abstract: A method and apparatus for determining the location of stuck pipe are provided. In one embodiment, the method includes the step of attaching a free point logging tool to a working line such as a slickline or wireline. The free point logging tool has a freepoint sensor and, optionally, an acoustic sensor. The freepoint sensor acquires magnetic permeability data in a string of pipe, while the acoustic sensor acquires acoustic data in the pipe. Two sets of data for each sensor are acquired—one in which the pipe under investigation is unstressed, and one in which the pipe is stressed. The first set and second sets of magnetic permeability data are compared to determine the stuck point location for the pipe. The first and second sets of acoustic data are compared to determine the nature in which the pipe is stuck.

Abstract: An apparatus for use in a well comprises a structure having at least a first portion formed of a first material, and a detector to detect a signal associated with a component located either within or beyond the structure. The first material has a property that reduces attenuation of the signal.

Abstract: A method for operating a downhole tool. The method includes moving an instrument through a wellbore, and the instrument includes a first non-acoustic transponder that is adapted to detect identification codes. An identification code detected from at least one second non-acoustic transponder is compared to a reference code. The at least one second non-acoustic transponder is attached to an emplaced structure in the wellbore, and the comparison is performed when the instrument moves by the at least one second non-acoustic transponder. The downhole tool is then operated if the identification code matches the reference code. A downhole tool operation system including at least one first non-acoustic transponder emplaced in a wellbore and adapted to communicate an identification code.

Abstract: A downhole tool for use in a well bore comprises an onboard navigation system for determining the location of the tool within the well bore, wherein the tool is moved along at least a partial length of the well bore via an external force. A method of locating a downhole tool in a well bore comprises deploying the tool along at least a partial length of the well bore via an external force, and self-determining the location of the tool without receiving communications from the surface. In an embodiment, the tool is a well bore zonal isolation device.

Abstract: Magnetic locator systems and methods of using same at a wellhead are described. The magnetic locator systems include a magnetic field generator on an oilfield tool component, such as a deployment bar, adapted to be moved through an oilfield pressure control component, such as a blow-out preventer, lubricator, riser pipe, or wellhead, and a magnetic field sensor located outside of the pressure control component adapted to detect the magnetic field and thus the position of the tool component in the pressure control component. The systems and methods of the invention provide safer and more efficient operation of oil and gas well pressure control systems. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: A method of determining the stuck point in a bore hole is provided. The method employs a device, such as an inductor or coil, for writing magnetic marks into the bore hole casing. The device is incorporated into a retrieval tool so that when a decision is taken to back off from the bore hole and recover any down hole equipment, the magnetic marks can be written on the casing of the bore hole as the retrieval tool is lowered into place. As the retrieval tool is raised in the bore hole, lifting the down hole equipment towards the surface, the magnetic marks are read using a three dimensional magnetic field sensor disposed either in the fishing tool or in the down hole apparatus itself.

Abstract: Methods and apparatus provide for the characterization of injected fluid flow within a wellbore. Particular embodiments include injecting a slurry comprising a particulate material and a carrier fluid into an isolated wellbore annulus and acquiring composite density readings at one or more discrete locations along the annulus while depositing the particulate material. Interpreting the acquired composite density readings provides an evaluation of the placement of the deposited particulate material within the isolated wellbore annulus. A further step may include determining when the slurry reaches each of the discrete locations as indicated by increases in the composite density reading at each of the discrete locations and furthermore, acquiring a maximum composite density reading at each of the discrete locations along the tubular member as an indication of the quantity of deposited particulate material at each of the discrete locations.

Abstract: An autonomous robot performs maintenance and repair activities in oil and gas wells, and in pipelines. The robot uses the well and pipeline fluids to provide most of the energy required for the its mobility, and to charge a turbine from which it may recharge batteries or power a motor for additional propulsion. A control system of associated systems controls the robot, enabling the robot to share plans and goals, situations, and solution processes with wells, pipelines, and external control systems. The control system includes decision aids in a series of knowledge bases that contain the expertise in appropriate fields to provide intelligent behavior to the control system. The intelligent behavior of the control system enables real time maintenance management of wells and pipelines, through actively collecting information, goal-driven system, reasoning at multiple levels, context sensitive communication, activity performing, and estimation of the operators' intent.

Abstract: A tool for multiple purposes features one ore more dogs that can engage a collar groove or restriction sub in the wellbore. The dogs are extendable through a sleeve biased in opposed directions and are supported from a mandrel. The dogs can retract into mandrel grooves to clear restrictions on the trip into the well. On the way up to a collar that has just been passed, the dogs engage and an upward pull on the mandrel displaces fluid through a restriction to allow enough time to get a meaningful surface signal of the overpull force. Thereafter, the applied force can be reduced as the dogs release at a lower applied force to reduce the slingshot effect. The tool can be inverted and used to keep a constant force on a bottom hole assembly during offshore drilling where a heave compensator is employed.

Abstract: A method for performing operations and for improving production in a well includes the steps of: providing radio identification devices at known locations in the well, and providing a reader device configured to read the identification devices, and to control the operations responsive to signals from the identification devices. The method also includes the steps of providing a process tool, and transporting the process tool and the reader device through the well. The reader device is programmed to control the process tool upon reception of a response signal from a selected identification device. The method can be used to perform perforating processes, packer setting processes, bridge plug setting processes, logging processes, inspection processes, chemical treating processes, and cleaning processes. In addition, the method can be performed dynamically by controlling the tool as it moves through the well, or statically by stopping the tool at a particular location within the well.

Abstract: It is important to know the precise position of equipment when testing of the BOP, testing the wellhead, flow testing the well, kick control, well circulation and testing of spool trees between the wellhead and the BOP. Accordingly, there is provided a system for determining the real time position of equipment within a bore, the system including a data input means for inputting data concerning the physical characteristics of components which are run into the bore; a sensing means located, in use, within the bore and including a sensor for determining data concerning at least one physical characteristic of the equipment at a given time; a data storage means for recording the inputted data and the determined data; and a comparison means for comparing the input data and the determined data to establish which part of the equipment is being sensed by the sensor.

Abstract: A device and method for retrieving a tool string from downhole locations through the use of one or more engagement sensors. The one or more engagement sensors are activated by the tool string engaging an overshot device. The one or more engagement sensor may be mechanical, electric, or magnetic and may be located at various locations on the overshot device, the tool string, or both. Additionally, any number of engagement sensors may be used at the same time.

Abstract: The present invention provides methods and apparatus for determining the location of an apparatus in a wellbore. The method includes lowering the apparatus with a conveying member and measuring a parameter associated with the conveying member. Thereafter, the measured parameter is used to determine the location of the apparatus as well as other conditions in the wellbore. The apparatus includes a conveying member operatively connected to an object released downhole. The apparatus may also include a dispensing apparatus coupled to one end of the conveying member. Preferably, the conveying member is a fiber optics line capable of transmitting optical signals. Other types of conveying members include a wire, a tube, and a cable. Additionally, a sensor may be disposed on the object and connected to the conveying member.

Abstract: To reduce the surveying error in a wellbore, the creation of several reference points within a borehole is carried out by physically placing borehole markers in the borehole casing, the borehole wall or in the formation itself, and providing an accurate reference of the marker locations by either storing information specific to the borehole markers inside or on the marker itself, or assigning an identification number to the marker and storing the information relating to that identification number remotely in a database. The borehole markers may contain an electronic module which includes a microcircuit, a transponder dedicated to the transmission and reception of data to/from a detector placed on a wireline tool, a drill string or a coiled tubing. The detectors may have an additional role of interrogating the electronic modules.

Abstract: An apparatus and method for horizontally drilling for detecting subsurface features and avoiding such features during closed-loop control of an underground drilling machine. A horizontal drilling system includes a base machine capable of propelling a drill pipe rotationally and longitudinally underground. A cutting tool system is coupled to the drill pipe, and a control system controls the base machine. A detector is employed to detect a subsurface feature. A communication link is utilized for transferring data between the detector and the control system. The control system uses the data generated by the detector to modify control of the base machine in response to detection of the subsurface feature.

Abstract: Methods, apparatus, and systems for obtaining information regarding a formation, a casing, or fluid within the casing are provided which utilize an interrogator and one or more sensing devices attached to a casing in a wellbore. The interrogator is located within and may be movable inside the wellbore. The sensing device is positioned and fixed in an opening in the casing. The sensing device includes a housing and a sensor with associated electronic circuitry. The interrogator and sensing device include a magnetic coupling therebetween that is operable when the interrogator and sensing device are positioned in close proximity to one another. Preferably, the magnetic coupling is realized by at least one solenoid winding for the interrogator and at least one solenoid winding for the sensing device, which provide a loosely-coupled transformer interface therebetween. The interrogator and sensing device communicate in a wireless manner over the magnetic coupling therebetween.

Abstract: A member having a body, the body having two spaced-apart ends, wave energizable identification apparatus which, in one aspect, is radio frequency identification apparatus with integrated circuit apparatus and antenna apparatus on the exterior of the body, and encasement structure encasing the identification apparatus, the encasement structure, in certain aspects, including one or a plurality of layers of heat resistant material and, in certain aspects, at least one layer of heat resistant material, and methods for producing such a member.

Abstract: An apparatus (60) for actuating a well tool (148) in a wellbore includes a downhole robot (62) that provides for locomotion within the wellbore (144). A pressure control member (64) having a deployed position is operably associated with the downhole robot (62). An engagement mechanism (66) is operably associated with the downhole robot (62) and releasably engages with the well tool (148) such that when the engagement mechanism (66) engages the well tool, the pressure control member (64) is in the deployed position and a differential pressure is created across the pressure control member (64), the downhole robot (62) transmits a longitudinal force to actuate the well tool (148).

Abstract: Methods and apparatus comprise a conveyance structure to carry a tool into a wellbore. The conveyance structure contains an optical fiber line to enable communication between the tool and well surface equipment. In one implementation, the conveyance structure comprises a slickline. In another implementation, the conveyance structure includes another type of conveyance device that does not convey power and data separate from the fiber optic line.

Abstract: A detector assembly and methods including a magnetoresistive sensor capable of detecting anomalies in the wall of a casing string disposed in a wellbore. Examples of anomalies include gaps between casings such as due to casing joints, air gaps in casing threads such as due to flush casing joints, enlarged casing wall thickness such as due to external casing collars, damaged casing, perforations, and other discontinuities or deformities in the casing. The detector assembly and methods detect perturbations in the earth's magnetic field caused by the anomalies. The detector assembly generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: A method for logging a wellbore includes actuating a positioning device to adjust the position of a module relative to a reference point or object such as a wellbore axis or proximally positioned downhole device. With respect to a wellbore, an exemplary positioning device can set the measurement tool such as an acoustic device to successive radial positions (e.g., substantial concentricity or substantial eccentricity relative to an axis of the wellbore). In one embodiment, the module includes a measurement tool to measure different parameters of interest (e.g., acoustic logging data, check-shot data measurement, bonding of cement to casing). With respect to an adjacent downhole device, the positioning device can provide a selected relative orientation (e.g., azimuth, inclination, radial displacement) between the module and the adjacent downhole device. The positioning device can also be adapted to apply a jarring force to a wall of the wellbore to free a downhole device.

Abstract: An apparatus for use in circulating cement in a casing in a wellbore is described having a first component such as a sensor disposed on the casing and a second component such as a detectable device disposed at a fluid interface formed between the cement and a fluid. The sensor may be a sensor coil mounted on the perimeter of the lower end of the casing, while the detectable device may be a transponder capable of emitting Radio Frequency Identification signals to the sensor to signal its arrival at the lower end of the casing. The transponder may be encased in a protective covering. Also described is a method of cementing a casing utilizing a first component such as a sensor disposed on the casing and a second component such as a detectable device disposed in the cement.

Abstract: A method is provided for estimating the position of a movable device in a borehole. The method comprises the steps of: (a) providing a prior location probability distribution associated with a first position of the device in the borehole, (b) providing a measurement of a putative distance moved by the device and/or a measurement of a characteristic of the surroundings of the device, the or each measurement being associated with movement of the device to a subsequent position in the borehole, and (c) calculating a posterior location probability distribution associated with the subsequent position, the posterior location probability distribution being conditional on the prior location probability distribution, and the or each measurement.

Abstract: Methods and systems for optical endpoint detection of a sliding sleeve valve are disclosed. The system comprises fiber optic cable based sensors (e.g., fiber Bragg gratings or fiber optic coils) positioned in a recess within the valve's housing and affixed proximate to the ends of the cavity in which the sleeve travels. When the sleeve reaches the ends of the cavity, it imparts a stress onto an area of the housing, which preferably constitutes a protrusion within the cavity, which in turn stresses the sensor and changes its reflection profile. This change in reflection profile indicates that the sleeve has traveled to an end point inside the valve, and accordingly that the valve is fully open or fully closed.

Abstract: Methods and apparatus are provided that permit downhole tools to be run into a well along with logging tools that can log the downhole tools into place by real time transmission of the data to a surface location. In one aspect, an apparatus includes a telemetry tool, a logging tool in communication with the telemetry tool and a downhole tool.

Abstract: Improved methods, apparatus, and systems for obtaining information regarding a formation, a casing, or fluid within the casing utilize an interrogator and one or more sensing devices attached to a casing in a wellbore. The interrogator, which is located and typically movable inside the wellbore, is effectively a toroidal transformer which includes an elongate conducting body surrounded by a core of high magnetic permeability material and carrying a winding. The sensing device, which is positioned and fixed in an opening cut in the casing, includes a housing, a sensor with associated electronic circuitry and an electrode. The electrode is insulated from the casing by an insulator, and the housing of the sensing device is typically adapted to provide a hydraulic seal with the opening in the casing. The interrogator and sensing device communicate in a wireless manner.

Abstract: Flowable devices provide communicate between surface and downhole instruments. The flowable devices having unique addresses are introduced into the flow of a fluid flowing in the wellbore. The flowable devices are used for providing information to a downhole controller and/or retrieving information from a downhole device.

Abstract: A sensing apparatus is provided for use downhole, comprising a housing and sensing means with the housing containing a plurality of separable elements to which data acquired by the sensing means is transferred. The separable elements are releasable from the housing to convey the acquired data to surface. The separable elements have a spherical outer casing of around 1 to 10 cm diameter which surrounds a memory chip. The casing has a sealable aperture so that electrical connection to the chip can be established within the housing.

Abstract: The present invention provides an apparatus and method for conveying downhole tools within a borehole using a continuous rod. The apparatus may include a continuous rod, a downhole tool attached to one end of the continuous rod, and a delivery rig for lowering the continuous rod and downhole tool into the wellbore.

Abstract: An apparatus and method is provided for locating joints in coiled tubing operations. The apparatus is adapted for running into a well on coiled tubing and for use during reverse circulating and fracturing operations. The apparatus having a central passageway for fluids, a collar locator module, a one-way valve coupled to the central passageway to allow for the flow of fluids in one direction but not the other, a port coupled to the central passageway to allow fluids to exit when the one-way valve is functioning, a movable cover module to cover the port to build up pressure in the central passageway, and a flow diverting module for permanently diverting the flow of fluids from the port to the central passageway.

Abstract: An autonomous system for performing a well operation at a predetermined location in a wellbore comprises a tool string having at least one well tool, a motive device for traversing the wellbore, and a control system adapted to position the tool string near the predetermined location. The control system comprises (i) a sensing system for detecting mass irregularities in the wellbore and (ii) a processor system having a processor with memory for storing at least one well log. The processor acts under programmed instructions to compare sensor signals to the stored well log to determine a tool string position in the wellbore. The control system also contains circuits for controlling the operation of the well tool and the motive device.

Abstract: An apparatus and method are employed to detect underground objects for use with a horizontal directional drilling (HDD) machine. A drill pipe is configured to cooperate with the HDD machine to produce a horizontal bore. A transmit apparatus is provided with the drill pipe and transmits electromagnetic probe signals ahead and/or to the side of the drill pipe. A receive apparatus is provided with the drill pipe and receives electromagnetic return signals resulting from the probe signals. A processor, coupled to the transmit and receive apparatuses, compares at least some of the return signals, and generates an alert signal indicative of a detected object in proximity with the drill pipe. HDD machine activity is modified, such as by reducing or halting drill pipe advancement, in response to the alert signal.

Abstract: A method for optimally orienting perforations in a subterranean formation is disclosed, the optimization process being based on establishing the orientation of bedding planes in the formation and, where applicable, hole size effects while determining an orientation of the perforation that balances the stress concentration along the circumference of the cross-section between perforation and bedding plane in further improvements of the method inhomogeneous stress distributions and permeability are included into the optimization process.

Abstract: The present invention provides a method and an apparatus for use in a wellbore tool. The apparatus includes a body and a sliding member, wherein the sliding member and a mechanical portion moves between a first position and a second position. A valve assembly causes the sliding member and mechanical portion to shift to its second position at a predetermined flow rate of fluid through the body. The invention also provides an apparatus for a downhole tool that includes a mandrel and a sliding member disposed on the mandrel. The sliding member including a plurality of fingers and a plurality of heads, wherein the plurality of fingers are slideably recessed within a plurality of longitudinal grooves. The invention further provides a collet assembly that includes a body and at least two extendable members, whereby as the members extend outward, the members are rotated.

Abstract: Methods, apparatus, and systems for obtaining information regarding a formation, a casing, or fluid within the casing are provided which utilize an interrogator and one or more sensing devices attached tod a casing in a wellbore. The interrogator, which is located and typically movable inside the wellbore, is effectively a toroidal transformer which includes an elongate conducting body surrounded by a core of high magnetic permeability material and carrying a winding. The sensing device, which is positioned and fixed in an opening cut in the casing, includes a housing, a sensor with associated electronic circuitry and an electrode. The electrode is insulated from the casing by an insulator, and the housing of the sensing device is typically adapted to provide a hydraulic seal with the opening in the casing. The interrogator and sensing device communicate in a wireless manner.

Abstract: Methods, apparatus, and systems for obtaining information regarding a formation, a casing, or fluid within the casing are provided which utilize an interrogator and one or more sensing devices attached to a casing in a wellbore. The interrogator is located within and may be movable inside the wellbore. The sensing device is positioned and fixed in an opening in the casing. The sensing device includes a housing and a sensor with associated electronic circuitry. The interrogator and sensing device include a magnetic coupling therebetween that is operable when the interrogator and sensing device are positioned in close proximity to one another. Preferably, the magnetic coupling is realized by at least one solenoid winding for the interrogator and at least one solenoid winding for the sensing device, which provide a loosely-coupled transformer interface therebetween. The interrogator and sensing device communicate in a wireless manner over the magnetic coupling therebetween.

Abstract: A well logging system that has, as its goal, the collection of information normally acquired by a dip log tool based on conductivity or resistivity measurements, but with the advantages of radiation based well logging systems. Unlike conductivity based dip log systems, the radiation-based system can be implemented in cased or uncased boreholes. The combination system incorporates a number of radially arrayed devices that, though structurally distinct, function much like the arms associated with conductivity dip log devices. The system incorporates radiation detectors positioned in a radial array rather than electrodes. The combination system measures radiation in each of the multiple radial orientations and responds to generated radiation in the respective directions. The sensitivity of the radiation measuring devices is set so as to localize the region of the borehole being measured.

Abstract: Methods and apparatus are provided that permit downhole tools to be run into a well along with logging tools that can log the downhole tools into place by real time transmission of the data to a surface location. In one aspect, an apparatus includes a telemetry tool, a logging tool in communication with the telemetry tool and a downhole tool.

Abstract: A detector assembly and methods including a magnetoresistive sensor capable of detecting anomalies in the wall of a casing string disposed in a wellbore. Examples of anomalies include gaps between casings such as due to casing joints, air gaps in casing threads such as due to flush casing joints, enlarged casing wall thickness such as due to external casing collars, damaged casing, perforations, and other discontinuities or deformities in the casing. The detector assembly and methods detect perturbations in the earth's magnetic field caused by the anomalies. The detector assembly generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: An apparatus for use in circulating cement in a casing in a wellbore is described having a first component such as a sensor disposed on the casing and a second component such as a detectable device disposed at a fluid interface formed between the cement and a fluid. The sensor may be a sensor coil mounted on the perimeter of the lower end of the casing, while the detectable device may be a transponder capable of emitting Radio Frequency Identification signals to the sensor to signal its arrival at the lower end of the casing. The transponder may be encased in a protective covering. Also described is a method of cementing a casing utilizing a first component such as a sensor disposed on the casing and a second component such as a detectable device disposed in the cement.

Abstract: An adhesive composition comprising(A) An epoxide resin component,(B) A hardener component, and incorporated in either or both/or (A) and (B) a thermoplastic polymer, mixtures thereof and application of said mixtures to substrate surfaces to adhere said surfaces together are described.