Abstract: A back pressure control choke operates to automatically control and maintain a desired back pressure on the fluid passing through the choke. The choke housing has an inlet channel which intersects with an axial bore, part of which bore constitutes the discharge channel. An annular choke seat concentrically arranged in the discharge channel of the axial bore is adapted to receive an annular choke element. The choke element is affixed to a shuttle which is mounted on a fixed mandrel extending into the axial bore of the choke housing. The shuttle is dynamically sealed against the housing and mandrel such that a closed chamber is created in that portion of the axial bore opposite the discharge channel. The shuttle element is constructed to be fluid balanced such that it will move to achieve an equilibrium of pressure on its forward and rear surfaces.

Abstract: An automatic cleaning system is provided for a mud separator apparatus. Water and mud inputs to a mud pump feeding the separator are respectively controlled by two butterfly valves ganged for cooperation, and operated by a single valve actuator motor. When the mud separator is shut off, a time delay relay is actuated which keeps the mud separator rotor motor on line during a predetermined flush cycle. The valve actuator opens the water valve, and closes the mud valve, permitting the separator to be flushed with water. Activating the start button returns the valve actuator to the position in which the mud valve is open and the water valve is closed, thereby returning the apparatus to the mud separation cycle.

Abstract: Method and apparatus are described to reduce the tension required on a riser pipe used in offshore drilling between a floating vessel and a subsea wellhead. Heavy drilling fluid is circulated down a drill pipe and up the annulus between the drill pipe and the borehole wall to a point just above a subsea wellhead. From this point, a separate drilling fluid return conduit extends to the floating vessel. Means are provided to maintain a constant level of an interface between the heavy returning drilling fluid and the lightweight fluid which can be confined within the riser pipe.

Abstract: Mud choke apparatus is disclosed, and the preferred embodiment has the form of a hollow, tubular body receiving a mud flow introduced from a lateral port, the flow being directed through an axial passage and past a valve seat. The valve seat is a replaceable, hardened metal liner and is formed with a gradual taper so that the mud flows from the large end through the tapered, smaller end. Thereafter, it flows out of the body through an axial opening. The flow of mud is throttled by a tapered, hardened plug serving as a valve element which is received into the valve seat. A hydraulic cylinder and piston with a connecting rod move the plug. The plug has a surrounding, perpendicular shoulder which seals and seats against a shoulder on the insert to fully close the throttling valve apparatus. Flow is choked by inserting the tapered plug with controlled clearance into the tapered valve seat.

Abstract: A machine pre-start warning device comprises at least one water spray nozzle and at least one temperature dependent resistor, the or each temperature dependent resistor being located with respect to a nozzle as to lie in the water jet emitted in use by the nozzle. The temperature dependent resistor is connected to a control circuit to actuate the control circuit upon sensing a water jet which circuit enables machine start-up to occur when the circuit is actuated and which otherwise prevents start-up from occurring.

Abstract: This apparatus disclosed in its preferred form is a choke for controlling the flow of drilling mud which is highly abrasive. The abrasive drilling mud is introduced through a lateral port and an elongate, tubular body. In the tubular body, a fluid actuated, double acting piston is forced to a choke control position. The piston has appended to it a centralized, tubular extension which receives a sleeve of wear resistant material. The sleeve is positioned in a circular chamber communicated to the lateral port where the drilling mud is introduced. It travels toward a seat downstream of the body. The seat is formed of hardened material. The downstream outlet of the body is additionally lined with a wear resistant sleeve. An alternate embodiment is also disclosed. A hydraulic control system for operation of the choke is also disclosed.

Abstract: A gas bubble is circulated from a well by a system that maintains the well and bottom hole pressure substantially constant by progressively increasing the casing pressure as needed to maintain the drill pipe pressure substantially constant. An incrementally increasing casing pressure reference signal is produced by detecting each occurrence of the drill pipe pressure falling a predetermined amount below a drill pipe pressure reference signal. The casing pressure reference signal is compared with the actual casing pressure. A throttling valve is closed a corresponding amount if the acutal casing pressure is less than the casing pressure reference signal. The throttling valve is opened a corresponding amount if the actual casing pressure is greater than the casing pressure reference signal.

Abstract: This apparatus disclosed in its preferred form is a choke for controlling the flow of drilling mud which is highly abrasive. The abrasive drilling mud is introduced through a lateral port and an elongate tubular body. In the tubular body, a fluid actuated, double acting piston is forced to a choke control position. The piston has appended to it a centralized tubular extension which receives a sleeve of wear resistant material. The sleeve is positioned in a circular chamber communicated to the lateral port where the drilling mud is introduced. It travels toward a seat downstream of the body. The seat is formed of hardened material. The downstream outlet of the body is additionally lined with a wear resistent sleeve.

Abstract: A system and method are disclosed which eliminates the use of a riser pipe in underwater drilling operations. The system includes a mud sump connectable to the top of a submerged wellhead and has a bottom with a mud inlet provided therein and an upwardly extending wall cooperating with the bottom to support a quantity of mud, the sump restricting the water to contact with only the upper surface of the mud as the mud passes upwardly through the mud inlet in the bottom. A hose, separate from the drill string, is used to carry mud to the surface of the water. A pumping means is used to pump mud through the hose in response to the quantity of mud supported within the sump to thereby return the mud to the surface of the water without the use of a riser pipe.

Abstract: This specification discloses a system and method for flushing and cleaning a hydrocyclone used in removing drilled solids from a drilling mud circulated in the drilling of a borehole. The system is comprised of a feed pump connected via a mud conduit to the inlet of a hydrocyclone. A check valve is located in the mud conduit intermediate the feed pump and the inlet of the hydrocyclone which allows the mud to flow through the mud conduit only in the direction toward the hydrocyclone. Another conduit for flowing a cleaning liquid is connected with the mud conduit on the hydrocyclone side of the check valve. A valve responsive to a signal, pressure or electrical, is located in this other conduit intermediate the mud conduit and a supply of cleaning liquid.

Abstract: An underreaming tool with cutter arm position indication. An elongated body portion has a coupling for coupling one end thereof to a lower end of a lower drill string. A pair of arms are pivotally mounted on the body portion. Means is provided for relatively positioning the cutter arms apart in a cutting position and closer together in a non-cutting position and having an overridable condition wherein either of the cutter arms may be either in a cutting or a non-cutting position. A fluid passage is provided in the body portion comprising an input port at one end of the body portion and first and second output ports. One output port is adjacent to each of the cutter arms.

Abstract: There is disclosed a device and a method for controlling the flow of fluid from a well bore. The device comprises a fluid control valve placed in the choke line of a well and has a shaped helical or spiral duct formed in one embodiment by a tapered screw-like plug engaging a hollow sleeve. In another embodiment, the plug is cylindrical and screw-like threads are formed in the hollow sleeve. The valve increases the degree of control over well bore pressure and flow rate as the well bore pressure fluctuates. The valve responds automatically to changes in the well bore pressure and is controlled by a control system including a hydraulic circuit and controls which visually indicate the position of the screw-like plug with respect to the hollow sleeve. The movement of the plug is controlled by the control system and the net pressure exerted on the plug by the fluid flowing through the control valve from the well bore.

Abstract: A combination of means to detect rotation of a pipe string and means to detect flow of fluid through a pipe string is utilized to cause down hole apparatus to carry out preferred actions if the sequence of rotation rate change and flow rate change is of one character, other activities being carried out if different sequences occur. Alternately, a choice of several actions to be taken by down hole apparatus may be elected by sustaining a flow condition while rotational conditions are manipulated at the earth surface.