Abstract: Diverting flow in a drilling fluid circulation system to regulate drilling fluid pressure. A pump of a drilling fluid pressure regulation system for a well bore can discharge drilling fluid through discharge piping at flow rate. A pressure control device has an inlet connected to the discharge piping and an outlet connected to bypass piping. A processor connected to the pump and the pressure control device can adjust the pressure control device to modify a pressure of the drilling fluid by at least partially opening the pressure control device and releasing drilling fluid into the bypass piping at a selected flow rate. The processor can modify the drilling fluid flow rate in the discharge piping based on the pressure represented by the pressure measurement signals and the selected flow rate in the bypass piping such that the target pressure parameter of the drilling fluid in the discharge piping is satisfied.

Abstract: A method for operating a dual drill string disposed in a wellbore, the string having a shutoff valve for at least a fluid return drill string therein proximate a bottom end thereof includes pumping fluid into the fluid return string such that a pressure therein is substantially equal to a fluid pressure in the wellbore. Circulation of fluid in the wellbore is initiated by pumping fluid into a fluid supply string of the dual drill string such that the shutoff valve on the fluid return string opens to enable the fluid leaving the wellbore to enter the fluid return string.

Abstract: A control apparatus for use in controlling the fluid pressure in a borehole during drilling of the borehole, the apparatus including an inlet suitable for connection to a pump, a main outlet suitable for connection to a drill pipe, and an overflow outlet suitable for connection to a fluid reservoir, the inlet being connected to the main outlet by a main flow conduit, and the overflow outlet being connected to the main flow conduit by means of an overflow conduit, wherein the overflow conduit is provided with a pressure regulator by means of which the pressure of fluid in the main flow conduit may be maintained at or around a predetermined pressure value.

Abstract: A pressure containment device for containing pressure in an annulus around a tubular body, the device comprising a housing having an axis and a passage extending generally parallel to the housing axis, and a seal assembly comprising a seal located in the housing to surround and enter into sealing engagement with a tubular body extending along the passage, wherein the housing is provided with a returns outlet port, an injection port, and an overflow outlet port, all of which extend through the housing from the exterior of the housing into the passage, the injection port being located between the returns outlet port and a first end of the seal, and the overflow outlet port being located adjacent a second, opposite end of the seal, and thus being separated from the injection port by the seal.

Abstract: A method of monitoring a well for unwanted formation fluid influx is disclosed. Measurements of well outflow are acquired during a period in which drilling operations are performed for the well. Occurrences of stagnant flow events during the period are determined. An outflow signature is generated from the well outflow measurements for each stagnant flow event. The outflow signatures are displayed sequentially in time of occurrence. Each outflow signature is analyzed for an anomaly.

Abstract: A method for optimizing drilling includes initializing values of a plurality of drilling operating parameters and drilling response parameters. In a computer, an initial relationship between the plurality of drilling operating parameters and drilling response parameters is determined. A drilling unit to drill a wellbore through subsurface formations. The drilling operating parameters and drilling response parameters are measured during drilling and entered into the computer. A range of values and an optimum value for at least one of the drilling response parameters and at least one of the drilling response parameters is determined in the computer. A display of the at least one of the plurality of drilling operating parameters and the at least one of the drilling response parameters is generated by the computer.

Abstract: A drilling control system monitors and compares drilling and completion operation sensor values and autonomously acts in response to conditions such as a kick or surge. Sensors in various combinations may monitor return fluid flow rate, fluid inflow rate, wellhead bore pressure, temperature of returning fluid, torque, rate of penetration and string weight change. The control system has corresponding control logic to monitor, warn and act based on the sensor inputs. The actions may include the warning of support personnel, closing an annular blowout preventer, shearing drill pipe using a ram shear, pumping heavier fluid down choke and kill lines, disconnecting the riser or various other actions.

Abstract: A method of drilling a subterranean wellbore using a drill string comprising the steps of: a. injecting a drilling fluid into the well bore via the drill string and removing said drilling fluid from an annular space around the drill string (the annulus) via an annulus return line, b. oscillating the pressure of the fluid in the annulus, c. determining the wellbore storage volume and wellbore storage coefficient for each fluid pressure oscillation, d. using the wellbore storage volume and wellbore storage coefficient to determine the proportion by volume of gas and proportion by volume of liquid in the annulus during that pressure oscillation.

Abstract: Air compressor systems, upgrade kits, computer readable medium, and methods for controlling an air compressor for improved performance. The methods may include receiving a working air requirement; determining an estimated air pressure of the air compressor to deliver the working air requirement; measuring a pressure of the air compressor; comparing the measured pressure with the calculated estimated air pressure; if the measured pressure of the air compressor is greater than the determined estimated air pressure by a predetermined greater amount, then decreasing an output control of the air compressor; and if the measured pressure of the air compressor is less than the calculated estimated air pressure by a predetermined lesser amount then increasing the output control of the air compressor. The air compressor may be controlled based on a measured pressure of delivered working air. An oil control system may shut off oil to parts of the air compressor.

Abstract: A system is provided for communicating within a borehole using controlled vibrations. A movement mechanism uses mechanical energy provided by a mechanical energy source to enable translational movement of a first surface relative to a second surface to allow the first surface to repeatedly impact the second surface to produce a plurality of vibration beats. The vibration beats will occur whenever the mechanical energy is provided by the mechanical energy source at one of at least three impact levels. A vibration control mechanism selectively controls an amplitude of the plurality of vibration beats to encode information therein. The amplitude of a vibration beat is selectively controlled by regulating the impact of the first surface and the second surface to one of the at least three impact levels.

Abstract: Embodiments of the present invention include methods and apparatus for dynamically controlling pressure within a wellbore while forming the wellbore. In one aspect, one or more pressure control apparatus are used to maintain desired pressure within the wellbore while drilling the wellbore. In another aspect, pressure is dynamically controlled while drilling using foam to maintain a substantially homogenous foam flow regime within the wellbore annulus for carrying cuttings from the wellbore.

Abstract: Injection of gas into a managed pressure drilling system to provide for operation of the drilling system in a downhole pressure window defined by the pore pressure of a formation being drilled and a fracture pressure of the formation. Gas injection being controlled so as to produce the desired downhole pressure without causing large oscillations in borehole pressure.

Abstract: A method and apparatus for estimating the instantaneous rotational speed of a bottom hole assembly at the lower end of a drill string. In one embodiment, a method includes driving the drill string by a drilling mechanism at the upper end of the drill string. A fundamental frequency of stick-slip oscillations suffered by the drill string is estimated. Variations in a drive torque of the drilling mechanism are determined. Known torsional compliance of the drill string is combined with the variations in the drive torque. An output signal representing the instantaneous rotational speed is provided.

Abstract: Back pressure control devices used to control fluid pressure in a wellbore require various utilities for operation, such as an air supply. Apparatus disclosed herein provide for the continued operation of one or more back pressure control devices when supply of utilities for operation of the back pressure control devices are intentionally or unintentionally interrupted.

Abstract: Stable back pressure control devices are used to control fluid pressure in a wellbore to provide constant downhole pressure. Back pressure may be estimated from a correlation between the speed of a mud pump and the pressure exerted from the pump. Drilling plans disclosed herein provide for the continued operation of one or more back pressure control devices for providing constant bottomhole pressure when casing connections are being made.

Abstract: A method of controlling standpipe pressure in a drilling operation can include comparing a measured standpipe pressure to a desired standpipe pressure, and automatically adjusting a choke in response to the comparing, thereby reducing a difference between the measured standpipe pressure and the desired standpipe pressure. A standpipe pressure control system for use in a drilling operation can include a controller which outputs an annulus pressure setpoint based on a comparison of a measured standpipe pressure to a desired standpipe pressure, and a choke which is automatically adjusted in response to the annulus pressure setpoint. A well system can include a standpipe line connected to a drill string in a wellbore, a sensor which measures pressure in the standpipe line, and a controller which outputs an annulus pressure setpoint based at least in part on a difference between the measured pressure and a desired standpipe pressure.

Abstract: A system and method are provided for producing controlled vibrations within a borehole. In one example, the system includes a movement mechanism and a vibration control mechanism. The movement mechanism is configured to use mechanical energy provided by a mechanical energy source to enable translational movement of a first surface relative to a second surface to allow the first surface to repeatedly impact the second surface to produce a plurality of vibration beats, where the vibration beats will occur whenever the mechanical energy is provided by the mechanical energy source unless the provided mechanical energy is dampened to prevent the translational movement. The vibration control mechanism is configured to selectively control an amplitude of the vibration beats to encode information therein, where the amplitude of a vibration beat is selectively controlled by dampening the provided mechanical energy to regulate the impact of the first surface and the second surface.

Abstract: A method of testing an earth formation can include incrementally opening a choke while drilling into the formation is ceased, thereby reducing pressure in a wellbore, and detecting an influx into the wellbore due to the reducing pressure in the wellbore. Another method of testing an earth formation can include drilling into the formation, with an annulus between a drill string and a wellbore being pressure isolated from atmosphere, then incrementally opening a choke while drilling is ceased, thereby reducing pressure in the wellbore, detecting an influx into the wellbore due to the reducing pressure in the wellbore, and determining approximate formation pore pressure as pressure in the wellbore when the influx is detected. Drilling fluid may or may not flow through the drill string when the influx is detected. A downhole pressure sensor can be used to verify pressure in the wellbore.

Abstract: A computerized monitoring system and corresponding method of monitoring the status and health of a blowout preventer. The system includes a graphics display at which a graphical user interface (GUI) displays the health of various sealing elements and control systems by way of “traffic light” indicators. The health indicators are evaluated, by the monitoring system, based on a risk profile for each of the indicated elements and control systems. The risk profiles are evaluated based on inputs such as measurement inputs, feedback signals, mechanical positions, diagnostic results, drilling conditions, and other status information of the blowout preventer at a given time and based on levels of redundancy and levels of deviation from normal conditions. The GUI includes recent history of changes in operating condition, and alarm indications such as poor health, along with the times of those events.

Abstract: A method for controlling drilling fluid rate in a wellbore is disclosed. A drill string is disposed into the well and connected to a formation testing or sampling tool. Drilling fluid is circulated at a first rate through the drill string. Data related to the wellbore, a formation about the wellbore or the formation sampling tool is transmitted to a processor. Upon analysis of the data, the drilling fluid circulation rate is changed to a second rate that is different from the first rate.

Abstract: This application is directed to a pressure balanced mud motor. The mud motor includes a power section to rotate a passageway housing and propel fluid through a passageway disposed in the passageway housing. The mud motor also includes a hydraulic apparatus for balancing a pressure drop experienced across a bearing assembly due to frictional flow of fluid through the passageway.

Abstract: A pressure compensation system for a wellbore instrument coupled to a drill string includes a shaft rotatably mounted with respect to an instrument housing. A lubrication chamber included in the instrument has at least one bearing for rotatably supporting the shaft. The lubrication chamber includes a face seal coupled on one face to the shaft and on another face to the housing. A pressure compensator establishes hydraulic communication between the lubrication chamber and the interior of the drill string. The compensator includes a barrier to fluid movement between the lubrication chamber and the interior of the drill string. The barrier enables pressure communication therebetween. The compensator includes a pressure communication port extending between the barrier and a portion of the shaft exposed to the interior of the drill string.

Abstract: A method and system to aid and/or train well control personnel by measuring the actual hydraulic delay and pressure attenuation of operator choke changes during well control operations or simulations. This provides the choke operator with an anticipated drillpipe pressure as soon as the choke is adjusted, accounting for hydraulic delay, pressure attenuation and prior choke adjustments that are currently travelling through the wellbore as well as reflections of the transient pressure waves against the pumps and choke. The technique that is described utilizes only three inputs, and works without knowledge of or inputting data such as well depth, pipe and hole geometry, mud properties, temperature, water depth, land, offshore platform or floating (subsea BOP's) drilling rigs. Further, the system can detect and warn the operator of potential problems based on the results of the real time analysis.

Abstract: A method of identifying a self-sustained influx of formation fluids into a wellbore includes the steps of closing an annular shut-off device and diverting an annular return flow from the wellbore through a first flow rate measurement device, measuring a flow rate of said annular return flow, measuring an inlet flow rate of fluids entering the well through a second flow rate measurement device in a fluid injection line, and identifying a self-sustained influx of formation fluids if a non-decreasing measured annular return flow rate is greater than said measured inlet flow rate.

Abstract: A method and apparatus for estimating the instantaneous rotational speed of a bottom hole assembly at the lower end of a drill string. In one embodiment, a method includes driving the drill string by a drilling mechanism at the upper end of the drill string. A fundamental frequency of stick-slip oscillations suffered by the drill string is estimated. Variations in a drive torque of the drilling mechanism are determined. Known torsional compliance of the drill string is combined with the variations in the drive torque. An output signal representing the instantaneous rotational speed is provided.

Abstract: A method of drilling a subterranean borehole comprising: a) pumping a drilling fluid down a drillstring (12), the drillstring (12) having a bit (14) at an end thereof, b) rotating the drillstring (12) about its longitudinal axis so that the bit forms a borehole (10) in the ground, the method further comprising the steps of: c) determining a desired drilling fluid flow rate range d) determining the desired upper and lower limits of the fluid pressure at the bottom of the wellbore (the BHP); e) determining the viscosity of drilling fluid which will maintain the BHP within the range set by the upper and lower BHP limits over the entire or the majority of the required drilling flow rate range; f) adjusting the composition of a drilling fluid to bring the drilling fluid to the viscosity calculated in step e above.

Abstract: A system and method for the drilling of ground holes by a track steer drill rig including a drilling arrangement that permits the speed of drilling holes to be balanced against the stability of the hole thus formed.

Abstract: A method of drilling a subterranean well bore using a tubular drill string described. One embodiment of the method includes the steps of injecting a drilling fluid into the well bore via the drill string and removing said drilling fluid from an annular space in the well bore around the drill string via a return line. The method can also include oscillating the pressure of the fluid in the annular space in the well bore, and monitoring the rate of flow of fluid along the return line.

Abstract: Systems, apparatus and methods are described for purposes of initiating a response to detection of an adverse operational condition involving a system including a drill rig and an inground tool. The response can be based on an uphole sensed parameter in combination with a downhole sensed parameter. The adverse operational condition can involve cross-bore detection, frac-out detection, excessive downhole pressure, a plugged jet indication and drill string key-holing detection. A communication system includes an inground communication link that allows bidirectional communication between a walkover detector and the drill rig via the inground tool. Monitoring of inground tool depth and/or lateral movement can be performed using techniques that approach integrated values. Bit force based auto-carving is described in the context of an automated procedure.

Abstract: A camera can be associated with each conference participant endpoint. The camera, either frame or video-based, can monitor and detect one or more of gestures, facial recognition, emotions, and movements of the conference participant. Based on the detection of one or more of these triggering events, a correlation to an action corresponding the triggering event can be evoked. For example, if a participant raises their hand, e.g., a triggering event, the system can recognize that this is a request to speak. The participant can then be queued in the system based, for example, relative to other participants' requests. When the other participants have finished speaking, and it is the time for the user who raised their hand to speak, the system can optionally queue the user by modifying the endpoint with which they are associated.

Abstract: A system and method for safely controlling a well being drilled or that has been drilled into a subterranean formation in which a conventional blow-out preventer operates to close the well bore to atmosphere upon the detection of a fluid influx event. Fluid pressures as well as fluid flow rates into and out of the well bore are measured and monitored to more accurately and confidently determine the fracture pressure and pore pressure of the formation and perform well control operations in response to a fluid influx event. During a suspected fluid influx event, one or more of the fluid flow and pressure measurements are used to confirm the fluid influx event and to safely regain well control by circulating the fluid influx out of the well through a choke line while maintaining the pressure inside the well between specified, selected limits, such as between the fracture and pore pressures.

Abstract: A method for maintaining pressure in a wellbore during drilling operations includes the steps of providing fluid from a reservoir through a drill string, circulating the fluid from the drill string to an annulus between the drill string and the wellbore, isolating pressure in the annulus, measuring pressure in the annulus, calculating a set point backpressure, applying back pressure to the annulus based on the set point back pressure, diverting fluid from the annulus to a controllable choke, controllably bleeding off pressurized fluid from the annulus, separating solids from the fluid, and directing the fluid back to the reservoir. An apparatus for maintaining pressure in a wellbore during drilling operations includes an adjustable choke for controllably bleeding off pressurized fluid from the wellbore annulus, a backpressure pump for applying a calculated set point backpressure, and a processor for controlling the adjustable choke and backpressure pump.

Abstract: An apparatus and method for reducing temperature along a bottomhole assembly during a drilling operation is provided. In one aspect the bottomhole temperature may be reduced by drilling a borehole using a drill string having a bottomhole assembly at an end thereof, circulating a fluid through the drill string and an annulus between the drill string and the borehole, diverting a selected portion of the fluid from the drill string into the annulus at a selected location above the drill bit to reduce pressure drop across at least a portion of the bottomhole assembly to reduce temperature of the bottomhole assembly during the drilling operation.

Abstract: A method of drilling a wellbore can include drilling the wellbore with a continuous tubing drill string, and sensing at least one parameter with an optical waveguide in the drill string. A well system can include a continuous tubing drill string, and an optical waveguide in the drill string. The optical waveguide may sense at least one parameter distributed along the drill string.

Abstract: A downhole tool string component has a through-bore intermediate first and second tool joints adapted for connection to adjacent tool string components. A blind-hole is formed in an outer surface of the component. A processing unit is also disposed within an outer surface of the component. An electrical device that is disposed within the component is in communication with the processing unit through an electrically or optically conductive medium which has a self-aligning pattern.

Abstract: A method of drilling a subterranean well bore using a tubular drill string is described. One embodiment of the method includes the steps of injecting a drilling fluid into the well bore via the drill string and removing the drilling fluid from an annular space in the well bore around the drill string via a return line. The method can also include oscillating the pressure of the fluid in the annular space in the well bore, and monitoring the rate of flow of fluid along the return line.

Abstract: A Drill-To-The-Limit (DTTL) drilling method variant to Managed Pressured Drilling (MPD) applies constant surface backpressure, whether the mud is circulating (choke valve open) or not (choke valve closed). Because of the constant application of surface backpressure, the DTTL method can use lighter mud weight that still has the cutting carrying ability to keep the borehole clean. The DTTL method identifies the weakest component of the pressure containment system, such as the fracture pressure of the formation or the casing shoe leak off test (LOT). With a higher pressure rated RCD, such as 5,000 psi (34,474 kPa) dynamic or working pressure and 10,000 psi (68,948 kPa) static pressure, the limitation will generally be the facture pressure of the formation or the LOT. In the DTTL method, since surface backpressure is constantly applied, the pore pressure limitation of the conventional drilling window can be disregarded in developing the fluid and drilling programs.

Abstract: An arrangement and a method to control and regulate the bottom hole pressure in a well during subsea drilling at deep waters: The method involves adjustment of a liquid/gas interface level in a drilling riser up or down. The arrangement comprises a high pressure drilling riser and a surface BOP at the upper end of the drilling riser. The surface BOP has a gas bleeding outlet. The riser also comprises a BOP, with a by-pass line. The drilling riser has an outlet at a depth below the water surface, and the outlet is connected to a pumping system with a flow return conduit running back to a drilling vessel/platform.

Abstract: A well drilling method can include transporting a pressure optimization unit to a rig site, the pressure optimization unit including a choke manifold, a control system which automatically controls operation of the choke manifold, and a flowmeter which measures flow of drilling fluid through the choke manifold, and then interconnecting the pressure optimization unit to rig drilling equipment. A pressure optimization unit for use with a well drilling system can include a choke manifold, a control system which automatically controls operation of the choke manifold, and a flowmeter which measures flow of drilling fluid through the choke manifold. The choke manifold, control system and flowmeter may be incorporated into a same conveyance which transports the pressure optimization unit to a rig site.

Abstract: A well drilling method can include transporting a pressure optimization unit to a rig site, the pressure optimization unit including a choke manifold, a control system which automatically controls operation of the choke manifold, and a flowmeter which measures flow of drilling fluid through the choke manifold, and then interconnecting the pressure optimization unit to rig drilling equipment. A pressure optimization unit for use with a well drilling system can include a choke manifold, a control system which automatically controls operation of the choke manifold, and a flowmeter which measures flow of drilling fluid through the choke manifold. The choke manifold, control system and flowmeter may be incorporated into a same conveyance which transports the pressure optimization unit to a rig site.

Abstract: A well system can include an accumulator in communication with a wellbore, whereby the accumulator applies pressure to the wellbore. A method of maintaining a desired pressure in a wellbore can include applying pressure to the wellbore from an accumulator in response to pressure in the wellbore being less than the desired pressure. Another well system can include a dampener in communication with a wellbore isolated from atmosphere, whereby the dampener mitigates pressure spikes in the wellbore.

Abstract: A method of controlling standpipe pressure in a drilling operation can include comparing a measured standpipe pressure to a desired standpipe pressure, and automatically adjusting a choke in response to the comparing, thereby reducing a difference between the measured standpipe pressure and the desired standpipe pressure. A standpipe pressure control system for use in a drilling operation can include a controller which outputs an annulus pressure setpoint based on a comparison of a measured standpipe pressure to a desired standpipe pressure, and a choke which is automatically adjusted in response to the annulus pressure setpoint. A well system can include a standpipe line connected to a drill string in a wellbore, a sensor which measures pressure in the standpipe line, and a controller which outputs an annulus pressure setpoint based at least in part on a difference between the measured pressure and a desired standpipe pressure.

Abstract: A well drilling system for use with a drilling fluid pump includes a flow control device regulating flow from the pump to a drill string interior; and another flow control device regulating flow through a line in communication with an annulus. Flow is simultaneously permitted through the flow control devices. A method of maintaining a desired bottom hole pressure includes dividing drilling fluid flow between a line in communication with a drill string interior and a line in communication with an annulus; the flow dividing step including permitting flow through a flow control device interconnected between a pump and the drill string interior; and the flow dividing step including permitting flow through another flow control device interconnected between the pump and the annulus, while flow is permitted through the first flow control device.

Abstract: A method of controlling the annular pressure in a well during a well construction operation. The operation comprises pumping a fluid down a tubing located within the well and extracting the fluid that flows back through an annulus within said well and surrounding the tubing. The method comprises defining a set pressure pref, determining a desired extraction flow rate qc of fluid from said annulus in dependence upon the set pressure pref and a pumped flow rate into the annulus, and configuring an extraction path to achieve said desired extraction flow rate.

Abstract: A method for reducing temperature of a bottomhole assembly during a drilling operation is disclosed, that, in one aspect, may include: drilling a borehole using a drillstring including a bottomhole assembly by circulating a fluid through the drillstring and an annulus between the drillstring and the borehole, pausing drilling, continuing circulating the fluid through the dill string and the annulus. The method further includes diverting a portion of the fluid from the drillstring into the annulus at a selected location above the drill bit to reduce temperature of the bottomhole assembly.

Abstract: A well drilling method utilizing real time response to ahead of bit measurements. A well drilling method includes measuring a property of a portion of the earth prior to drilling a wellbore into the earth portion; and varying a drilling parameter in real time while drilling the wellbore, in response to measuring the property.

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

Abstract: A control apparatus for use in controlling the fluid pressure in a borehole during drilling of the borehole, the apparatus including an inlet suitable for connection to a pump, a main outlet suitable for connection to a drill pipe, and an overflow outlet suitable for connection to a fluid reservoir, the inlet being connected to the main outlet by a main flow conduit, and the overflow outlet being connected to the main flow conduit by means of an overflow conduit, wherein the overflow conduit is provided with a pressure regulator by means of which the pressure of fluid in the main flow conduit may be maintained at or around a predetermined pressure value.

Abstract: A drilling system includes a downhole well control device that can be used to control out-of-norm wellbore conditions. The downhole well control device can control one or more selected fluid parameters. The well control device in cooperation or independent of surface devices exerts control over one or more drilling or formation parameters to manage an out-of-norm wellbore condition. An exemplary well control device hydraulically isolates one or more sections of a wellbore by selectively blocking fluid flow in a pipe bore and an annulus. The control device also selectively flows fluid from the pipe bore to the annulus. A communication device provides on-way or bidirectional signal and/or data transfer between the controller(s), surface personnel and the well control device. Exemplary application of the well control device include controlling a well kick, controlling drilling fluid being lost to the formation and controlling a simultaneous kick and loss.

Abstract: A drilling tool includes a hydraulically driven device (21) for advancing a drilling head (2) in a bore (5), and a flow limiter (30) arranged in a hydraulic conduit (25) of the advancing device (21) for adjusting an advancing speed of the drilling head (2) in the bore (5), with the flow limiter (30) having a pressure-actuated adjusting member (38) for adjusting flow of a hydraulic fluid in the hydraulic conduit means (25) in accordance with a flow volume of a rinsing fluid (7) for rinsing the bore.