Abstract: Methods and systems are provided for maintaining fluid pressure control of a well bore 30 drilled through a subterranean formation using a drilling rig 25 and a drill string 50, whereby a kick may be circulated out of the well bore and/or a kill fluid may be circulated into the well bore, at a kill rate that may be varied. A programmable controller 100 may be included to control execution of a circulation/kill procedure whereby a mud pump 90 and/or a well bore choke 70 may be regulated by the controller. One or more sensors may be interconnected with the controller to sense well bore pressure conditions and/or pumping conditions. Statistical process control techniques may also be employed to enhance process control by the controller. The controller 100 may further execute routine determinations of circulating kill pressures at selected kill rates.

Abstract: A method for controlling a subsea well that includes shutting at least one blowout preventer, opening at least one isolation line, and circulating an influx out of a well while an inlet pressure of a subsea mudlift pump is adjusted to maintain a substantially constant drill pipe pressure at an initial circulating pressure. After the influx is circulated out of the well, drilling mud with a kill mud weight is pumped into the well. The drill pipe pressure is reduced according to a preselected drill pipe pressure decline schedule until the kill mud weight drilling mud reaches the bottom of the well. The drill pipe pressure is then maintained at a final circulating pressure by adjusting the inlet pressure of the subsea mudlift pump. The kill mud weight drilling mud is then circulated from the well bottom to the surface at the final circulating pressure.

Abstract: A closed-loop drilling system and method of drilling oil, gas, or geothermal wells is described, whereby through the control of the flow rates in and out of the wellbore, and by adjusting the pressure inside the wellbore by a pressure/flow control device installed on the return line, surface pressure being increased or decreased as required, this in turn decreasing or increasing downhole pressure, occurrence of kicks and fluid losses may be greatly minimized and quickly controlled. Through the method of the invention the elimination of the kick tolerance and tripping margin on the design of the well is made possible, since the pore and fracture pressure will be determined in real-time while drilling the well, and, therefore, nearly no safety margin is necessary when designing the well, reducing significantly the number of casing strings necessary.

Abstract: The present invention provides drilling systems for drilling subsea wellbores. The drilling system includes a tubing that passes through a sea bottom wellhead and carries a drill bit. A drilling fluid system continuously supplies drilling fluid into the tubing, which discharges at the drill bit bottom and returns to the wellhead through an annulus between the tubing and the wellbore carrying the drill cuttings. A fluid return line extending from the wellhead equipment to the drilling vessel transports the returning fluid to the surface. In a riserless arrangement, the return fluid line is separate and spaced apart from the tubing. In a system using a riser, the return fluid line may be the riser or a separate line carried by the riser. The tubing may be coiled tubing with a drilling motor in the bottom hole assembly driving the drill bit.

Abstract: The present invention provides a method of monitoring a well to detect and provide warning of pipe sticking. The method includes 1) monitoring the downhole annular fluid pressure of a drilling fluid being pumped through the drill string during drilling over predetermined intervals of time to obtain a series of pressure measurements, 2) monitoring the torque required to rotate the drill string during said periods to obtain a series of torque measurements, and 3) comparing the series of downhole annular fluid pressure measurements with the series of torque measurements so as to identify corresponding changes in both, and 4) raising an alarm when the magnitude of the changes passes predetermined alarm values.

Abstract: A method for detecting a leak in a drill string valve used when drilling a subsea well. The method comprises measuring a first inlet pressure at a subsea mudlift pump while a subsea mudlift pump and a surface pump are operating and before a well is fully shut-in and measuring a second inlet pressure at the subsea mudlift pump after the mudlift pump and the surface pump are shut down and after the well is fully shut-in. The first and second subsea mudlift pump inlet pressure measurements are then compared, and a check is performed to determine if the subsea mudlift pump inlet pressure has increased by an amount greater than an estimated annular friction pressure.

Abstract: A method for a dynamic shut-in of a subsea mudlift drilling system. The method comprises detecting a kick, isolating a wellbore, and adjusting a subsea mudlift pump and a surface mud pump to provide a selected wellbore pressure. Selected well parameters are measured and used to calculate a kick intensity.

Abstract: A method for a dynamic shut-in of a subsea mudlift drilling system. The method comprises detecting a kick, isolating a wellbore, and adjusting a subsea mudlift pump and a surface mud pump to provide a selected wellbore pressure. Selected well parameters are measured and used to calculate a kick intensity. The invention is also a method for a dynamic shut-in of a subsea mudlift drilling system including detecting a kick and isolating a wellbore. A first inlet pressure of a subsea mudlift pump and a first drill pipe pressure are measured. A rate of the subsea mudlift pump and a rate of a surface mud pump are adjusted to pre-kick circulation rates. A second inlet pressure of the subsea mudlift pump and a second drill pipe pressure are recorded. The measured values are used to calculate a kick intensity.

Abstract: A mud separator monitoring system utilizing electronic transducers positioned in various locations in the mud separator and the lines leading from the mud separator to the mud return pit and gas discharge flare for obtaining data during drilling operations to calculate the volume of gas retained in the drilling fluid, the hydrostatic head of the drilling fluid and gas pressure in the separator on a continuing basis and informing field personnel of conditions in the mud separator indicating potential hazard. The system further monitors continuously the volume of injected gases and hydrocarbon gases circulated during drilling operations for making adjustments to the volume of injected gases required to sustain the drilling operations.

Abstract: The apparatus has a housing which is secured to the lower end of a drilling motor body and carries an arbor that is secured to the output shaft of the motor. The arbor has three segments serially connected by gimbals. The upper segment is axially fixed by the bearings of the motor and has a lower end that extends when actuated to push the center segment downward. Axial movement of the center segment actuates a cam to move it laterally. The lower segment extends from the housing as an output shaft. It is arranged to tilt relative to the housing and its upper end is moved laterally by the gimbal connected center segment. The resulting tilt of the rotating axis of the output shaft causes an attached drill head to drill a deflected well bore.

Abstract: An apparatus and method is provided for substantially continuously drilling and disposing of drill cuttings and dust to minimize airborne contamination while providing protection against overload using enhanced computer control. A drill stem with a bit is used to form the drill hole. A flushing mechanism utilizes vacuum or pressurized water to create a bailing fluid flow for flushing the cuttings and dust from the drill hole for disposal. A transducer monitors at least one first parameter of the bailing fluid flow, and a sensor may also monitor at least one second parameter of a flow of a driving fluid under pressure for feeding the drill stem and bit into the earth. A controller is utilized to regulate the rate of feed and/or driving of the stem and bit dependent on the levels of the parameters being monitored.

Abstract: A torque limiting device that allows a drill string to rotate relative to the cutting structure of the bit when a predetermined torque is applied between the cutting structure of the drill bit and the drill string. The torque limiting device utilizes a retaining member which restricts rotational movement of a first component of the torque limiting device relative to a second component. When a sufficient torque load is placed on the cutting structure of the drill bit, the retaining member allows rotational movement of the first component relative to the second component and allows the drill string to continue to rotate relative to the cutting structure of the bit until the torque is sufficiently reduced. The torque limiting device may be an integral part of a drill bit, may be a separate device attached between the drill string and the drill bit or between the drill string and a downhole motor, or may be part of a near-bit sub or incorporated in a downhole motor.

Abstract: An apparatus and method for controlling an underground boring machine during boring or reaming operations. A boring tool is displaced along an underground path while being rotated. In response to variations in underground conditions impacting boring tool progress along the underground path, a control system modifies the rate of boring tool displacement along the underground path while rotating the boring tool at a selected rotation rate to optimize excavation productivity. The controller may also monitor the rate at which liquid is pumped through the borehole and automatically adjust the rate of displacement and/or the liquid flow rate so that sufficient liquid is flowing through the borehole to remove the cuttings and debris generated by the boring tool.

Abstract: Flow control devices and associated control methods are described for use with hydraulic tools, such as those in a drill string. The described flow control device is typically incorporated into a drill string and is selectively operable in either a flow-through mode or a valve control mode. In the valve control mode, fluid pressure is increased or decreased within the drill string to selectively actuate a valve which is associated with the flow control device. In the flow-through mode, fluid pressure may be increased or decreased without operating the valve. Techniques are described for selectively moving the flow control device between the flow-through mode and the valve control mode. Wellbore fluid pressure readings provide signals to a rig operator for selectively moving the device in this manner.

Abstract: The present invention provides a fluid flow measurement system for an oil well drilling system that includes a supply of drilling fluid to a wellbore under pressure and a return line carrying fluid leaving the wellbore during drilling of the wellbore. The system includes at least one floating sensor in the return line that provides a measure of the velocity of the fluid in the return line. The sensor may be a thermal sensor, an electromagnetic sensor or an ultrasonic sensor. A height sensor provides the fluid level in the return line and a density sensor provides the density of the returning fluid. A controller determines the inflow rate and out flow rate of the drilling fluid and further determines the presence of a kick and wash out from the flow rates. The system also determines the operating condition of the pumps supplying fluid to the wellbore.

Abstract: Suction pressure pulses are generated within a borehole by closing a valve that interrupts the flow of a drilling fluid (e.g., drilling mud) circulating through one or more high velocity flow courses within the borehole. In one embodiment in which the suction pressure pulses are applied to improve the efficiency of a drilling bit, the valve interrupts the flow of drilling mud directed through the bit and thus through high velocity flow course(s) disposed downstream of the bit. Arresting flow of the drilling mud through the high velocity flow course(s) generates suction pressure pulses of substantial magnitude over a face of the drill bit. The suction pressure pulses provide a sufficient differential pressure that weakens the rock through which the drill bit is advancing and also increase the force with which the drill bit is being advanced toward the rock at the bottom of the borehole.

Abstract: Injection of a drilling fluid additive into a drilling fluid, as the drilling fluid is being pumped into a bore hole, in direct proportion to the amount of drilling fluid being pumped.

Abstract: A method and a toolstring for carrying out a downhole operation in a wellbore (e.g. milling a window in a well casing, drilling a lateral wellbore, etc.). The toolstring is comprised of a workstring and a downhole assembly which is comprised of a downhole, rotary motor (e.g. bent motor) for driving a cutting tool (e.g. carbide mill, drill bit, etc.) and a valve which is movable between a first position in which the flow of work fluid is blocked to the motor and a second position in which the fluid is now directed to the motor to thereby actuate the motor and drive the cutting tool. By initially blocking flow of fluid to the motor, certain functions can be performed within the wellbore (e.g. orienting the bent motor) before the motor begins any cutting within the wellbore.

Abstract: The valve, has an orifice and cooperating poppet with the poppet situated to approach the orifice to an extent determined by a controlling crosshead that reciprocates axially in response to manipulation of the mud flow moving through the valve. The amount of restriction provided by the valve is varied by selected manipulation of the drilling fluid flow controls at the surface. Pressure provided to controlled machinery is regulated by a valve by-pass channel. Changes in the standpipe pressure indicates the state of the valve action achieved down hole.

Abstract: A system includes a database that is adapted to store substantially continuously measured or calculated drilling parameters. At least one computer can access the database to display simultaneous user configurable graphical representations of selected drilling parameters. A user can observe multiple parameters graphically in real time.

Abstract: A drill bit (6) is equipped with one or more fluid jets (7) that are activated during a portion of the rotational movement of the drill bit (6). A processor (41) located with other down-hole sensors (33-38), is programmed with parameters defining the desired path of the borehole (8). The sensors (33-38) determine the actual spatial location of the drill bit (6) and provide the processor (41) with corresponding information. The processor (41) compares the actual drilling path to the desired path, and if a correction is required, a switching module (3) allows a pressurized drill fluid to be sequentially switched to selected jets (7) during rotation of the drill bit (6) to thereby erode the formation in a direction toward the desired path. With this arrangement, the problems of directional control by surface-located equipment are overcome.

Abstract: A mud separator monitoring system utilizing electronic transducers positioned in various locations in the mud separator and the lines leading from the mud separator to the mud return pit and gas discharge flare for obtaining data during drilling operations to calculate the volume of gas retained in the drilling fluid, the hydrostatic head of the drilling fluid and gas pressure in the separator on a continuing basis and informing field personnel of conditions in the mud separator indicating potential hazard. The system further monitors continuously the volume of injected gases and hydrocarbon gases circulated during drilling operations for making adjustments to the volume of injected gases required to sustain the drilling operations.

Abstract: A procedure is described for determining the power output of a downhole drilling motor, when the motor is inside the wellbore. The technique uses stand-pipe pressure and fluid flow rate as the main inputs. The power output of the motor is calculated by carrying out two low flow stall tests at flow rates lower than the drilling flow rate. These tests result in "off-bottom" and stall pressures at the two flow rates. Another off-bottom pressure is taken at the actual flow rate that will be used during drilling operations. From the use of the off-bottom and stall pressure measurements, a determination is made of the differential pressure across the motor and the stall pressure at the actual drilling fluid flow rate. A full power curve and a predicted operating stand-pipe pressure for optimal power generation are provided based on an experimentally verified assumption regarding the change in rotation rate of the motor versus the differential pressure across the motor power section.

Abstract: Methods and apparatus are provided for the uninterrupted transfer of oil and gas well drill cuttings from a collection point, such as a shale shaker trough, to several types of variously configured on rig and off rig receptacles. Two or more hoppers are arranged for alternating receipt and discharge of cuttings, the cuttings being continuously drawn to the hoppers by a suction force from an upstream blower. The receptacles utilized in the various embodiments are varied, such as barges, box containers, and slurry units. The hoppers are, in some embodiments, moved to remote locations, such as off rig barges, prior to beginning the cuttings transfer.

Abstract: The present invention relates to a device for remote actuating an equipment through a variation of the flow of a fluid in a pipe. The device includes an adjusting throttle (2, 3; 52, 51) adapted for varying the opening of the passageway of said fluid through a hydrodynamic action. The device further includes delay timing for adjusting the throttle. The present invention further relates to a method for actuating at least one equipment. Application of the device and of the method is to the actuation of equipment adapted for controlling the trajectory of a wellbore.

Abstract: A device for remotely actuating a piece of equipment by varying the flow conditions of a fluid, possibly incompressible, an comprising an actuating piston, a nozzle-needle assembly. One of the nozzle or the needle is mounted for sliding movement into the piston. An arrangement is provided for returning the slidably mounted nozzle or needle to a predetermined position relatively to the piston.

Abstract: A device for remotely operating equipment through a variation in the flow of a fluid includes a coupling unit connecting the device and the equipment to be operated, an assembly of two elements cooperating with one another to control an opening value of a channel through which the fluid flows and a control assembly for adjusting the opening value in order to have it take on one or the other of two particular values.

Abstract: Method and apparatus for actuating one or more downhole well tools carried by a production or workstring conduit having an imperforate wall and for blocking fluid communication between an activating fluid body and a second fluid source within said well across dynamic seals between actuating members of the well tool, by producing selective signals through the conduit wall detectable by a member to produce an activating signal for actuating the downhole well tool by a downhole energy source.

Abstract: The present invention is a device for the remote actuation of equipment (3) associated with a drill string (1) through a hydraulic displacement mechanism (10;53,58) co-operating with a distributor (7;25,26,27;47) associated with the drilling fluid. The displacement mechanism directly converts the hydraulic energy of the drilling fluid into actuating mechanical energy with the co-operation of no other fluid than the drilling fluid. The invention further relates to an actuating method using the device and has an application of directional drilling in the petroleum field.

Abstract: Controllable drill head containing an elongated body of which one end is attached to a bore pipe and a spout element is mounted in a turnable manner on the other, foremost end of the body, in and opposite to an opening in this body, wherein the head contains an elongated, elastic, bendable element which at one end carries the spout element and which has been mounted in the body in such a manner that when being in a rest position the movable element stretches out in the longitudinal direction of the body, but which is elastically bendable in the cross direction of the body so as to alter the direction of the spout element through bending, a mechanism for (3) stopping the foremost end of the bendable element with the spout element in the forward direction without the element bending through and to keep the spout element from changing direction, and a mechanism for exerting forward pressure on a part of the bendable element which is situated further away from the foremost end of the body than the foremost end th

Abstract: A fluid powered incremental stepping motor arranged to serve as a length of pipe string has a body that includes an arbor end with an arbor of reduced diameter extending into a bore of a housing end bearingly supported for rotation about the arbor. An annular space between arbor and housing contains a piston rotationally secured to the arbor for limited axial movement. The piston operates within the bore as a power cylinder and carries a flow resistor. Fluid channels extend through the body to accept fluid flow down the pipe string. Fluid flow urges the piston downward and a spring urges it upward. Cams on each end of the piston and mating cams in the housing bore engage at the upward and at the downward extreme of piston travel and at each engagement impart an increment of rotation of the housing relative to the arbor at each excursion of the piston. Increasing fluid flow down the pipe string and then decreasing the flow causes the piston to reciprocate at each flow rate change cycle.

Abstract: The present invention is a drilling tool including a telescoping assembly for transmitting hydraulic force to the drill bit at the bottom of the tool. The internal hydraulic characteristics of the tool may be varied to vary the force through extension and retraction of the telescoping assembly.

Abstract: A device for guiding a drilling tool into a well and for exerting a hydraulic force on the drilling tool includes a tubular body and an outer sleeve rotating about the body and longitudinally displaceable with respect to the body. Also, the device includes radially displaceable pistons, in an extension position, that come into anchoring engagement with the wall of the well and immobilize the external sleeve, as well as a jack to displace the body and the drilling tool integral therewith with respect to the external sleeve and to exert a pushing force onto the tool. Hydraulic circuits and appropriate control assembly are also provided for controlling the execution of a series of successive cycles of anchoring of the external sleeve in the well and of displacement of the drilling tool with respect to the external sleeve.

Abstract: A method of and a device for remotely-controlling at least one piece of drill string equipment from an instruction issued from the surface. The method includes issuing from the surface a first information sequence to cause a first predetermined action according to a predetermined sequence, detection of a condition indicative of a second sequence resulting from the first sequence, comparison of this second sequence with another predetermined sequence, and operating the equipment only if there is similarity between the latter two sequences. The method can be applied to actuation of a variable-angle bent element.

Abstract: To divert sufficient fluid flow through an unsealed bearing section of a downhole drilling motor, a flow control apparatus is provided for insertion between the power section of the motor and the bottom of a drill bit which is to be turned by the motor. The flow control apparatus includes a variable flow channel having a selectable effective cross-sectional area preferably embodied by a valve. A selected effective cross-sectional area is chosen by a control mechanism, such as a snap ring or a spring used to control the position of a valve member of the valve in response to different flow rates of fluid pumped through the valve depending upon whether the drill bit is on-bottom or off-bottom. In one embodiment the apparatus is incorporated within the interior of a drill bit which has angled flow channels to direct flushing fluid flow to side wall locations where reaming occurs. Flow through these outlets is controlled by positioning of the valve member.

Abstract: An improved directional drilling tool permits changing the downhole drilling assembly between straight and directional drilling configuration by manipulation of conventional drilling fluid flow controls at the surface. A housing, with stabilizer features, shrouds a shaft which functions as an extension of the drill string and attaches to a drill head. A drilling fluid flow rate responsive selector valve is situated in the shaft and responds to drilling fluid flow rate manipulations to change assembly configuration. In the straight configuration the shaft remains straight and is rotationally locked to the housing. In the directional configuration the housing is rotationally unlocked from the shaft, normally after directional orientation, so that the shaft can rotate through it. The same action transversely displaces the shaft midsection relative to the housing and the shaft and drill head below is angularly deflected by way of a hinge arrangement near the drill head end of the housing.

Abstract: A borehole tool employs a drill string having a plurality of sections of drill pipe connected together for traversing a wellbore. Drilling fluid is circulated down the drill string and up the annulus between the drill string and the wellbore to transport entrained drill cuttings out of the wellbore. At least one section of double wall drill pipe with its outer wall perforated, is included in the drill string. Drilling fluid flow down the string into the section of double wall drill pipe is controlled to effect a desired degree of drilling fluid flow rate through the perforations in the outer wall of the double wall drill pipe section so as to provide a stirring action to the drill cuttings in the wellbore annulus and thereby improve the transport of entrained drill cuttings out of the wellbore in the circulating drilling fluid.

Abstract: A drilling fluid pulse generator for use above a drill bit to produce pulsations in drilling fluid flow. An autocycling valve briefly interrupts the flow of fluid to bit jets to reduce the effective hydrostatic pressure at the drilling face and to hydraulic energy in the drill string to thoroughly scour the hole face when the briefly closed valve reopens. An alternate configuration provides a bypass route for fluid diverted from the bit, and the bypass includes jet nozzles to add energy to the return fluid stream to further reduce the effective hydrostatic pressure at the drilling face.

Abstract: A programmed automatic drill control for optimizing the drilling of subterranean holes by large drilling machinery such as blast hole drills. Sensing means are provided to sense a first set of drilling parameter limits to effect maximum r.p.m. of the motor to rotate the pipe drilling bit and to sense a second set of drilling parameter limits to effect a maximum rate for the motor to drive the hoist pull-down mechanism. These conditions will prevail until a sensed limit is reached or the drilling conditions require operation along a torque or force limit set value. When a limit is reached, the control will regulate at a value of r.p.m. or rate which is consistent with maintaining operation at the limit value.

Abstract: A normally straight drill string component for use just above a downhole drilling motor, or directional jet, that can be caused to be alternately straight or bent by cycling the drilling fluid flow rate between selected flow rate limits by use of controls at the earth surface.

Abstract: A control system for use on fluid conducting pipe strings in earth boreholes to permit cycling of fluid flow between preselected flow rates to change conditions downhole as a result of surface exercise of fluid flow controls. A resulting change of state downhole is indicated by a change in fluid flow related pressure detectable at the surface.

Abstract: A method for circulating and maintaining a drilling mud in a wellbore drilled into a subterranean formation at a desired pressure during drilling operations, said method consisting essentially of;(a) circulating drilling mud through a drill pipe in the wellbore into the wellbore, maintaining a desired pressure in said wellbore and recovering drilling mud from the wellbore at a controlled rate using a mud pump and mud pit arrangement; and,(b) maintaining a second supply of drilling mud in fluid communication with the drill pipe at a suitable pressure so that when the mud pump fails to maintain pressure in the drill pipe, drilling mud is supplied from the second supply of drilling mud to maintain pressure in the wellbore.

Abstract: In the representative embodiments of the present invention described herein, a new and improved directional drilling tool carrying a rotable drilling bit is dependently coupled to a rotatable drill string for excavating a borehole along one or more selected courses of excavation. Passage means on the directional drilling tool are communicated with the several fluid-discharge passages in the drill bit. A rotating flow obstructing member is arranged in the directional drilling tool for selectively communicating the drilling fluid with the bit passages as the drill bit is rotated. A selectively operable driver is arranged for rotating the flow-obstructing member at one rotational speed when it is desired to sequentially discharge drilling fluid into most, if not all, adjacent sectors of the borehole as the drill bit rotates so as to advance the drill bit along a generally linear course of excavation.

Abstract: A column of drill collars have holes or jets extending radially from the collar bore through the collar wall. A wash pipe extends full length through the bore of the perforated collars, so sized as to leave an annular flow space between the wash pipe and the collar bore wall. A remote control selector valve is situated such as to receive drilling fluid from the upwardly continuing drill string and direct the fluid through the wash pipe to the drill bit for regular drilling, or on cue from the earth surface, direct fluid to the annulus to be expelled through the drill collar perforations to help free stuck pipe or to prevent such sticking.

Abstract: A method and system for detecting and identifying abnormal drilling conditions. It determines the normal pump speed-pressure ratio over the range of usual working conditions. It measures the output pressure from the pump. And it measures the speed of the pump. Then it detects a change from the normal pump speed-pressure ratio which indicates abnormal conditions. Identification of the abnormal condition depends upon whether the pump speed increased above normal or the output pressure decreased below normal. If the former, the volume of drilling fluid returning is observed in order to identify one of three conditions. If the latter, the number of decreases greater than a predetermined extent are counted over a predetermined interval of time which may indicate malfunctioning pump valve or valves.

Abstract: A system, or apparatus combination, and apparatus components, for the measurement of fluid flow. Such system, or apparatus can be used, e.g., for measuring the amount or flow of drilling fluid, or mud, introduced into a well bore, the amount or flow of mud returned from the well bore, and differences in flow rate and density between the mud introduced into the well bore and the mud returned from the well bore. The system measures or calculates, inter alia, flow rates, viscosity, temperature, density and gas content and compensates for variations; and in marine installations the system additionally measures vessel motion and compensates for wave and tide motions.

Abstract: A drilling choke for controlling flow of drilling fluids from a well comprising: a body having an inlet and outlet and an intermediate cavity therebetween; a seat member coaxially disposed in the body outlet; an operator assembly removably attached to the body; and a stem assembly connected to the operator assembly for axial movement thereof. A portion of the stem assembly is removable, upon removal of the operator assembly from the body, without otherwise disturbing the operator assembly.

Abstract: A method for controlling the flow of drilling fluid through a subaqueous wellbore is disclosed. The method comprises the steps of continuously measuring the output flow rate (A) of the drilling fluid from the wellbore, the input flow rate (B) of the drilling fluid to the wellbore, and at least a component of the pitch and roll (P/R) of the vessel, computating a floating alarm limit (C) dependent upon the pitch and roll (P/R) signal and the roughness of the sea, filtering the periodic fluctuation of the output flow rate (A) due to the motion of the vessel, and computating the delta flow signal (D) by subtracting the input flow rate (B) from the filtered output flow rate (A).

Abstract: Diverter valve for preventing blow-outs in oil wells during the early stages of drilling. The diverter valve has a simplified construction which reduces maintenance problems during use in the field.

Abstract: A device for disabling the draw works of a well drilling apparatus responsive to the locking of the drill string by a blow out prevention device. The device comprises an air-actuated valve connected for regulating the flow of air to the air-actuated clutch of the draw works. A second valve regulates the flow of pressurized air to the air actuated valve. The second valve is responsive to the actuation of the blow out prevention device by an accumulator valve.