Abstract: A system including a first tubular, a second tubular configured to rest within a bore of the first tubular, a multi-metal seal system configured to seal a space between the first tubular and the second tubular, wherein the multi-metal seal system includes, a first metal seal portion with a first angled surface and a second angled surface, a second metal seal portion with a third angled surface, and a third metal seal portion with a fourth angled surface, wherein the first angled surface selectively engages the third angled surface at a first angled interface and the second angled surface selectively engages the fourth angled surface at a second angled interface, and wherein the first and second angled interfaces are configured to drive the first metal seal portion radially away from the second and third metal seal portions.

Abstract: Present embodiments are directed towards a system comprising a tension hanger having a parent bowl configured to mount in a mineral extraction system, wherein the parent bowl comprises a first retaining slot formed in an inner diameter of the parent bowl, wherein the first retaining slot is at least partially defined by an upper surface, a lower surface, a first side surface, and a second side surface, wherein the upper surface, lower surface, first side surface, and second side surface form a J-shaped configuration and a mandrel hanger configured to be disposed within the parent bowl, wherein the mandrel hanger comprises a first load shoulder configured to be positioned within the first retaining slot.

Abstract: A well system includes a local control unit configured to communicably couple to a well shut-in assembly at a well site, the well shut-in assembly operable to shut-in a wellbore based on a command from the local control unit; and a remote control unit configured to wirelessly communicate a line-of-sight airborne wireless signal, at a location remote from the local control unit and the well site, to initiate the command from the local control unit to the well shut-in assembly.

Abstract: The invention provides a cutting valve comprising a valve block, a gate, which is slidably within a cavity in the valve block from an open position to a closing and cutting position, an upper seat arranged in an upper part of the valve between the valve block and the gate, and a lower seat arranged in a lower part of the valve between the valve block and the gate, The valve further comprises an upper resilient member arranged between the upper seat and a lower resilient member arranged between the valve block and the lower seat. The cutting valve being distinctive in that the combination of height of upper seat, and lower seat, resilient member and any spacers on the lower side of the gate is selected so that an allowed travelling distance for the upper seat towards the valve block and an allowed travelling distance for the lower seat towards the valve block, are substantially equal.

Abstract: An obturator for actuating a downhole tool having a central bore. The obturator comprising a body of a size and shape to pass through the central bore of the tool and an engagement member releasably attached to the exterior of the tool body, the engagement member being of a size and shape to engage and actuate the tool.

Abstract: Expansion sealing elements used to prevent fluid, flow through an annul us formed by tubing within the well and the wall of the wellbore or casing are provided. The expansion sealing elements are useful on downhole tools including those that need to be lowered through a first casing to be set in a second casing, which, has a larger diameter than the first casing.

Abstract: An anchor structure is disclosed; the anchor structure is set on a mandrel of a downhole plugging apparatus. The anchor structure comprises (a) a clamping device, (b) a plurality of slips and (c) a conical slip holder, wherein the slips are connected to a conical face of the conical slip holder, and (d) a containing space between the clamping device and the slips; the anchor structure further comprises (e) a stroke pressure compensating device which is set within the containing space and can be compressed to provide pressure for the slips, wherein the containing space is designed to be able to accommodate whole or part of the stroke pressure compensating device in the situation that the slips are anchored into a wellbore wall and the clamping device is in contact with the conical slip holder. The containing space would prevent the stroke pressure compensation device from being damaged or extruded completely, and preclude the clamping device from contacting the slips directly when the slips retract.

Abstract: Embodiments of the disclosure pertain to a downhole system useable for isolating sections of a wellbore that includes a work string comprising a downhole end; a setting sleeve coupled with the downhole end; and a downhole tool engaged with the setting sleeve during run-in, the downhole tool further comprising a mandrel, a composite member, and at least one slip.

Abstract: A cement isolation fluid for use in a wellbore during a cementing operation includes an aqueous carrier fluid and a preformed synthetic polymer swellable in the carrier fluid, in an amount effective to isolate a cement slurry from another drilling fluid present in the wellbore. A method of cementing a wellbore comprising a drilling fluid includes injecting the cement isolation fluid into the wellbore; injecting a cement slurry into the wellbore; and hardening the cement in the slurry to cement the wellbore.

Abstract: A stabilization composition including a polymerizable ionic liquid (“PIL”) comprising a cationic group, an anionic group, and a polymerizable functional group, wherein the cationic group has a molecular mass in the range of about 20 g/mol to about 500 g/mol and the anionic group has a molecular mass in the range of about 30 g/mol to about 500 g/mol.

Abstract: An inflow control device comprising: a housing, wherein the housing comprises a receptacle and a receptacle opening; a plug, wherein the plug fits into the receptacle; and a cover sleeve, wherein the cover sleeve is positioned around a portion of the housing and comprises a cover sleeve port, wherein the cover sleeve is rotatable circumferentially around a longitudinal axis of the housing to align the cover sleeve port with the receptacle opening, and when the port and opening are aligned, the plug is positionable into the receptacle or removable from the receptacle. The inflow control device can be used in an oil, gas, or water production well, or an injection well to variably control the flow rate of a fluid flowing through the device.

Abstract: Disclosed is a subsurface safety valve with a magnetic booster feature. One disclosed safety valve includes a housing, a flow tube reciprocably disposed between an upper position and a lower position within the housing, a first magnetic element coupled to the housing, and a second magnetic element coupled to the flow tube and configured such that interaction of the first and second magnetic elements induces at least one of a first force on the flow tube when the flow tube is in the upper position and a second force on the flow tube when the flow tube is in the lower position.

Abstract: There is provided a flow control apparatus including a housing, a port, a flow control member, a sensor, and a trigger. The housing includes a housing passage. The port extends through the housing. The flow control member includes a fluid responsive surface, and is configured for displacement, relative to the port, such that fluid communication is effected between the port and the housing passage. The sensor is coupled to the housing for sensing an actuating signal. The trigger is configured for effecting fluid communication between the housing passage and the fluid responsive surface, in response to the sensing of an actuating signal by the sensor, for effecting displacement of the flow control member.

Abstract: Techniques for continuously circulating fluid into a drill string are disclosed. These techniques involve a circulation sub (108) including a tubular and a diverter valve (200A). The tubular has a first end connectable to the drill string, a second end connectable to a pipe segment, and a port (220) therein. The tubular has a fluid path (202) for allowing the fluid to flow from the pipe segment to the drill string and a circulation path (204) for allowing the fluid to flow from the port to the drill string. The diverter valve has a channel therethrough in selective fluid communication with the fluid path. The diverter valve is positionable between a flow through position for selectively allowing the fluid to flow through the fluid path and a diversion position for selectively allowing the fluid to flow through the circulation path whereby the fluid may continuously flow through the drill string.

Abstract: Disclosed are systems and methods that use dynamic underbalancing to increase fluid flow within a wellbore. A disclosed underbalance pressure generator device includes a housing having a first end and a second end and defining a piston chamber that extends between the first and second ends, a piston movably arranged within the piston chamber, one or more influx ports defined in the housing at or near the second end and configured to enable fluid communication between the piston chamber and an exterior of the housing, and a locking mechanism arranged at or near the second end and capable of securing the piston at or near the second end.

Abstract: A hydraulically-powered subsea tool system has a tool (26) and a tool power unit (12). The tool (26) communicates with a first connector element (30) on a hydraulic drive circuit (82). The tool power unit (12) has a hydraulic supply circuit (88) communicating with a second connector element (20). The connector elements are wet-mated with each other to connect the circuits for powering the tool. The circuits are pressure-compensated by respective compensators (136,90). When the circuits are connected, a valve (140) is operable to transfer pressure compensation of one of the circuits from the compensator (136) of that circuit to the compensator (90) of the other circuit. The valve (140) suitably transfers pressure compensation of the drive circuit from a drive circuit compensator to a supply circuit compensator.

Abstract: A method for orienting a tubing string in a wellbore comprises lowering a tubular string within a casing string in a wellbore, engaging the tubular aligning tool with a casing aligning tool while lowering the tubular string, rotating the tubular string in response to engaging the tubing aligning tool with the casing aligning tool, rotationally aligning the tubular string opening with a casing string opening disposed through the casing string based on the rotating, and retaining the tubular string opening in an axial aligning and a rotational aligning with the casing string opening. The tubular string comprises: a tubular string opening and a tubular string aligning tool.

Abstract: An example well system includes a base pipe having an interior and defining one or more flow ports, the base pipe being positionable within a wellbore adjacent a subterranean formation. A flow path for a fluid extends between the interior of the base pipe, through the one or more flow ports, and to an exterior of the base pipe. A transverse turbine is positioned in the flow path, the transverse turbine including a rotor and a plurality of blades positioned to receive a flow of the fluid perpendicular to a rotational axis of the rotor. A generator includes one or more magnets rotatable with rotation of the transverse turbine and one or more coil windings mounted on a stator. The flow of the fluid rotates the transverse turbine and rotation of the transverse turbine generates electrical power in the generator.

Abstract: Some metal surfaces are often unable to be contacted effectively with fluids containing hydrofluoric acid or acidic fluoride ions due to significant corrosion issues. Metal surfaces comprising titanium or a titanium alloy represent but one example. Corrosion inhibitor compositions comprising boric acid and other boron-containing compounds may at least partially suppress corrosion of titanium and titanium alloy surfaces.

Abstract: A containment system for recovering hydrocarbon fluid from a leaking device comprising a dome sealed to the seafloor around the leaking device and forming a cavity for accumulating hydrocarbon fluid. The dome comprises a first dome and a second dome connected to the first dome. The second volume of the second dome is smaller than the first volume of the first dome.

Abstract: Disclosed are flow distribution assemblies used to distribute a fluid flow into a surrounding subterranean formation. One flow distribution assembly includes one or more shunt tubes extending along an exterior of a base pipe that defines at least one flow port, the one or more shunt tubes being in fluid communication with the at least one flow port coupled to the one or more flow conduits and extending from the bulkhead along an exterior of the base pipe, and a plurality of shunt screens disposed on the one or more shunt tubes and having one or more openings defined therethrough, wherein the plurality of shunt screens facilitate fluid communication between the base pipe and an external environment.

Abstract: A liner installation system for use in a wellbore having a casing string disposed therein. The system includes a liner string having a liner hanger and a liner top and a setting tool having an expansion cone assembly and a locator cylinder. After running the liner string through the casing string such that at least the liner hanger is positioned within the wellbore casing, the setting tool is run through the casing string until the locator cylinder contacts the liner top. Thereafter, axially moving the expansion cone assembly through the liner string radially expands the liner hanger into contact with the casing string.

Abstract: An electromagnetic perforation device for well casings includes a coil disposed around a core carried by a mandrel. The device further includes a power supply coupled to a current supply device, which is coupled to said coil. A stabilizing member extends from the mandrel and spaced apart on the mandrel from the coil core. The electromagnetic performance device may be positioned in a well casing, and the current supply device may rapidly supply a current to the coil to created an electromagnetic field in the coil and simultaneously induces a magnetic field in the well casing. The coil, current, and well casing may be selected such that electromagnetic field and the magnetic field produce repulsive magnetic forces that are sufficient to overcome a yield strength of the well casing and perforate the well casing.

Abstract: An oil well pumping system having stroke optimization is provided. The system includes a downhole pump residing within a wellbore, and a rod string extending down into the wellbore and connected to the pump. The system also includes a well head having an actuator configured to reciprocate the rod string and connected downhole pump as upstrokes and as downstrokes, and a pump stroke controller. The pump stroke controller is configured to adjust a speed of the upstroke and a speed of the downstroke in response to signals indicative of pump fillage. In one aspect, the pump stroke controller tunes the pumping speed to match an average in-flow of production fluids into the pump over a multiple hour period to provide an optimum speed. A method for optimizing pumping speed at a wellbore is also provided herein.

Abstract: An apparatus for boosting the pressure of flowing fluids includes a plurality of jet pumps (10a, 10b), each having a LP inlet for LP fluid, a HP inlet for HP liquid and a MP outlet for MP fluid. A fluid separator device (16) is connected to receive the MP fluid from the outlets of the jet pumps, a gas outlet line (20) for a separated gas phase and a liquid outlet (22a, 22b) for separated liquid phase. A liquid return line (24b, 38) is connected to the liquid outlet of the fluid separator device and the HP inlets of the jet pumps (10a, 10b) for returning at least some of the separated liquid phase from the fluid separator device to the HP inlets of the jet pumps, and a mechanical pump (32) is connected into the liquid return line for boosting the pressure of the liquid delivered to the HP inlets of the jet pumps. A flow control system (6) is provided for controlling the flow of fluids through the respective jet pumps (10a, 10b).

Abstract: A technique facilitates automatic commissioning operations on pumping systems, e.g. electric submersible pumping systems. The automatic commissioning technique employs closed-loop monitoring and control processes which may include monitoring of pump shaft direction and speed measurements. In many applications, the technique reduces the time and manual effort otherwise involved in commissioning pumping systems in well completions. Embodiments also may be employed in automated decision-making related to commissioning and in determining operational settings based on sensed environmental and/or well performance conditions.

Abstract: Techniques for reducing a carbon emissions intensity of a fuel includes injecting a carbon dioxide fluid into a first wellbore; producing a hydrocarbon fluid from a second wellbore to a terranean surface; and producing a fuel from the produced hydrocarbon fluid, the fuel including a low-carbon fuel and assigned an emissions credit based on a source of the carbon dioxide fluid.

Abstract: Described herein are methods and system that use electromagnetic heating to heat wellbores and the fluids therein. The heating is achieved by placing one or more permanent magnets in the wellbore and moving a metallic component and/or the one or more permanent magnets relative to each other. This generates eddy currents in the metallic component, which heat the metallic component. This heat is transferred to the fluids in the wellbore from the metallic component by convection.

Abstract: Methods comprising: (a) introducing a pad fluid into a formation at a rate and pressure sufficient to create or enhance at least one fracture therein, wherein the pad fluid comprises a pad base fluid, micro-proppant particulates, a gas-generating chemical, and an activator, and wherein either the gas-generating chemical or the activator or both are encapsulated; (b) placing the micro-proppant particulates, the gas-generating chemical, and the encapsulated activator into the fracture; (c) releasing the activator from its encapsulation; (d) reacting the gas-generating chemical and the activator in the fracture so as to generate gas and heat, thereby creating or enhancing at least one microfracture therein; (e) introducing a fracturing fluid into the formation, wherein the fracturing fluid comprises a fracturing base fluid and macro-proppant particulates; and (f) placing the macro-proppant particulates into the fracture so as to form a proppant pack therein.

Abstract: A process to recover hydrocarbons, from a hydrocarbon reservoir having a bottom, using a substantially horizontal production well, the substantially horizontal production well having a toe and a heel, the process including: (a) injecting oxygen into the hydrocarbon reservoir, the horizontal production well having at least one perforation zone for contact with the reservoir; (b) injecting steam into the hydrocarbon reservoir; the oxygen producing in situ heat and in situ carbon dioxide by combustion and the steam producing in situ heat by conduction and condensation; the in situ carbon dioxide dissolving into the liquid hydrocarbon, lowering its viscosity; (c) recovering the reservoir liquid hydrocarbons of lowered viscosity using the substantially horizontal production well; and (d) optionally conveying the recovered liquid hydrocarbons to the surface; where the process is absent a removal step of any non-condensable gas from the reservoir.

Abstract: A process for altering a wettability characteristic of a carbonate formation to stimulate oil production includes selecting an oil bearing carbonate formation, injecting a silicide dispersion into the carbonate formation, and reacting the injected silicide dispersion with water. The reaction alters the wettability characteristic of the carbonate formation toward water wettability. The silicide dispersion can include an alkali metal silicide, such as sodium silicide. The reaction generates hydrogen, silicate, and heat that pressurizes the carbonate formation with the generated hydrogen, heats the carbonate formation with the generated heat, and reduces the viscosity of the hydrocarbons in the carbonate formation with the generated silicate. The reaction re-mineralizes the surfaces in the carbonate formation and alters the wettability characteristics of the carbonate formation as a calcium-silicon phase is formed. The hydrocarbons are recovered from the carbonate formation with a production well.

Abstract: A drill string includes drill pipe and a modular fracturing sub. A processor can control the drill string to drill a wellbore to some desired depth. The drill string is positioned at a desired location in the wellbore and a section of the wellbore is hydraulically isolated, forming a cavity. Existing fluid may be evacuated from the cavity and fracturing fluid injected into the cavity until a desired level of fracturing is attained. Retrievable packers are used for the hydraulic isolation. A pump evacuates the existing fluid via ports in the fracturing sub. The ports may also be used when injecting fracturing fluid. Seismic sensors may be distributed along the drill string to monitor fracture growth. Logging-while-drilling tools may be integrated into the drill string. Fluid from the lower portion of the wellbore is blocked by a lower sealing unit on a bottomhole assembly.

Abstract: Fracturing systems and methods for increasing the conductivity of a flow path between a reservoir formation and a wellbore are presented that include varying a proppant concentration of a fracturing fluid in response to a measured characteristic from the wellbore during the fracturing process. During the injection of proppant pulses into the wellbore, one or more of a pulse length, pulse height, pulse shape, or duty cycle of the proppant concentration is varied. Other systems and methods are disclosed.

Abstract: Methods of performing a fracture operation at a wellsite with a fracture network are provided. The methods involve obtaining wellsite data and a mechanical earth model, and generating a hydraulic fracture growth pattern for the fracture network over time. The generating involves extending hydraulic fractures from a wellbore and into the fracture network of a subterranean formation to form a hydraulic fracture network, determining hydraulic fracture parameters after the extending, determining transport parameters for proppant passing through the hydraulic fracture network, and determining fracture dimensions of the hydraulic fractures from the hydraulic fracture parameters, the transport parameters and the mechanical earth model. The methods also involve performing stress shadowing on the hydraulic fractures to determine stress interference between fractures at different depths, and repeating the generating based on the determined stress interference. The methods may also involve determining crossing behavior.

Abstract: There is provided apparatuses, and related systems, for effecting production of oil from a reservoir. A separator is provided and configured to mitigate problems with solid debris accumulation within the wellbore. A system is also provided, including the separator, and is disposed within a wellbore. A pump is also provided, and disposed in fluid communication with, and downstream from, the separator, for receiving reservoir fluids from which gaseous and solid material have been separated by the separator.

Abstract: A method of homogenizing a production fluid from an oil well having one or more wellbores includes separating gas from the production fluid in a vertical or horizontal section of a well casing at a first location spaced from a heel portion of a wellbore, and injecting the separated gas into the production fluid at a second location spaced from the heel portion of the wellbore and provided downstream of the first location.

Abstract: Techniques for controlling a bottom hole assembly (BHA) to follow a planned wellbore path include determining sensor measurements from the BHA; determining a model of BHA dynamics based on the sensor measurements from the BHA; determining a weighting factor that corresponds to a drilling objective; determining an objective function comprising the drilling objective, weighted by the weighting factor, and one or more constraints; determining a control input to the BHA that satisfies the objective function and the one or more constraints; and applying the control input to the BHA.

Abstract: A downhole drilling vibration analysis involves measuring orientation data in at least two orthogonal axes downhole while drilling with a drilling assembly. For example, two orthogonal magnetometers can be used. A toolface of the drilling assembly is determined using the measured sensor data, and velocity (RPM) values for the toolface for a plurality of revolutions of the drilling assembly are determined. From these determined values, a coefficient of variation for the toolface velocity (RPM) values for the revolutions of the drilling assembly is calculated. When a pattern in found in the toolface velocity (RPM) and/or the calculated coefficient of variations exceed one or more thresholds, the processing device determines that detrimental vibrations are occurring in the drilling assembly.

Abstract: A system and method for surface steerable drilling are provided. In one example, the system receives toolface information for a bottom hole assembly (BHA) and non-survey sensor information corresponding to a location of the BHA in a borehole. The system calculates an amount of incremental progress made by the BHA based on the non-survey sensor information and calculates an estimate of the location based on the toolface information and the amount of incremental progress. The system repeats the steps of receiving toolface information and non-survey sensor information and calculating an amount of incremental progress to calculate an estimate of a plurality of locations representing a path of the BHA from a first survey point towards a second sequential survey point.

Abstract: A downhole drilling tool may include a strain gauge inside a rolling-bearing element. For example, the downhole drilling tool may include a rolling-bearing element having an inner race, an outer race, and one or more bearings disposed between the inner and outer races; and a strain gauge disposed on an interior surface of the rolling-element bearing, the strain gauge including at least one circuit formed by (1) a first substrate and a second substrate defining a gap therebetween and having first conductive fibers and second conductive fibers, respectively, extending therefrom into the gap in an intermingling configuration, (2) an electrical connection between the first and second substrates, and (3) an electrical resistance sensor arranged within the electrical connection.

Abstract: A steering tool is movable by a drill string to form an underground bore along an intended path. A sensing arrangement of the steering tool detects its pitch and yaw orientations at a series of spaced apart positions along the bore, each position is characterized by a measured extension of the drill string. The steering tool further includes a receiver. At least one marker is positioned proximate to the intended path, for transmitting a rotating dipole field to expose a portion of the intended path to the field for reception by the receiver. The detected pitch orientation, the detected yaw orientation and the measured extension of the drill string are used in conjunction with magnetic information from the receiver to locate the steering tool. The steering tool may automatically use the magnetic information when it is available. A customized overall position determination accuracy can be provided along the intended path.

Abstract: Downhole slickline cable including a polymer matrix having reinforcing fibers embedded therein. A plurality of integrity-sensing optical fibers are embedded within the polymer composite and extend along an axial length of the downhole slickline cable that enables slickline cable structural and mechanical integrity self-diagnosis. The cable may include energy transmission lines that include one or more integrity-sensing optical fibers.

Abstract: Acoustic measurements are obtained and combined with some identification of regions that are expected or believed to be cemented. Based at least in part on this information, a processing unit derives an annular material classifier that can identify those measurements characteristic of the cemented regions (including regions cemented with a resin cement formulation), and that further applies the classifier to the measurements to generate a cement log that can be displayed to a user. Cross-plots of waveform amplitude, acoustic impedance, and the derivative of acoustic impedance, have revealed that resin cement, for example, has characteristic acoustic properties that form a small cluster within the range of expected measurements. For improved identification reliability, such clusters can be identified adaptively.

Abstract: A technique facilitates testing and monitoring of a well. An artificial lift system is operated to produce a well fluid, and data is collected as the artificial lift system is operated at different flow rates. The data collected at the different, e.g. varying, flow rates is used in estimating flow performance and to enable continued monitoring of the well. In some applications, the data may be obtained by utilizing a virtual flow metering technique.

Abstract: A method for calculating pore pressure of a subsurface includes the steps of obtaining a resistivity value while drilling in a region wherein there is a shallow depth (reference depth) where shale is in a hydrostatic condition, or where shale is not in hydrostatic condition but where the pore pressure at such depth can be estimated and calculating, using a processor, a pore pressure at a drilling location based on the following Formula (I): PP=OvB?(OvB?Hyd)(R/R0)øn wherein PP is pore pressure, OvB is the overburden value associated with the drilling location, Hyd is hydrostatic pore pressure, R is a measured value of resistivity, R0 is the resistivity at a reference depth or is an imposed value of resistivity, and øn is a normalized value of porosity.

Abstract: Apparatus, systems, and methods may include a magnetic dipole transmitter to be located in a ranging well. A voltage measurement device can include a plurality of probes where each probe is to be located on one of a target well, the ranging well or a surface of a geological formation comprising the ranging well and the target well. A controller coupled to the voltage measurement device calculates a distance or relative direction between the target well and the ranging well based on a voltage difference between the plurality of probes. The distance/direction can be used to control drilling operations. Additional apparatus, systems, and methods are disclosed.

Abstract: A system is described that is positionable downhole in wellbore for determining a parameter of a downhole tool. The system includes a tubing subassembly and a signal generator positioned in the tubing subassembly for outputting, in response to being covered or uncovered by a detectable portion of a downhole tool, a detectable signal for determining a parameter of the downhole tool.

Abstract: A method for monitoring fluid flow in a conduit comprises: acoustically coupling an optical fiber to the conduit adjacent one or more flow restrictions (R1-R4) in the conduit; inducing a Distributed Acoustic Sensing (DAS) assembly to measure an acoustic noise signature (SNR1-4) generated in the fiber by the fluid flowing through each flow restriction (R1-R4); deriving the fluid flow rate of the fluid (QI, QI+II) flowing through each flow restriction (R1-R4) from the measured acoustic noise signature (SNR1-4); and displaying the derived fluid flow rate (QI, QI+II) at a fluid flow rate monitoring display.

Abstract: The present invention provides a drilling auxiliary system, which is used for down hole EM data transmission and/or casing detection, wherein said drilling auxiliary system comprises an insulating device which is mounted on the drill pipe of a well and used for preventing entire electric current loss or suppressing partial electric current loss. When used for EM data transmission, the present invention can greatly reduce the unnecessary power consumption, thereby improving the efficiency of EM data transmission. When used for casing detection, the present invention can effectively increase the casing detection range.

Abstract: A crossbore detection system. The system is located in a downhole tool proximate a drill bit. The system comprises circuitry sensitive to a subsurface environment and a sensor that detects changes in the circuitry. The sensor detects changes in the circuitry that indicates that the drill bit has struck an underground pipe. The sensor may detect a series of electromagnetic signals indicative of the strike or may detect changes to an impedance bridge at a capacitive sensor.