Abstract: A downhole tool apparatus has a housing with a compression chamber defined therein. A fill passage is disposed through the housing for placing the compression chamber in open flow fluid communication with a well annulus so that well fluid may flow into the compression chamber as the apparatus is lowered into a well. An isolation valve selectively closes the fill passage to trap well fluid in the compression chamber. An operating element is operated by the actuating piston slidably disposed in the housing. A first side of the actuating piston is in fluid pressure communication with the compression chamber so that a volume of the compression chamber is decreased when the actuating piston moves between a first and second position thereof relative to the housing.

Abstract: An injection tool for use in injecting fluids through perforations in the well bore of an oil or gas well is mechanically set and mechanically releasable. Fluid can be injected between upper and lower packing elements into a selected perforation. The upper and lower packing elements on opposite sides of the perforation into which fluid is injected are retractable, and any pressure differential across the upper packing elements or across the lower packing elements can be separately equalized.

Abstract: A downhole tool apparatus has a housing with a compression chamber defined therein. A fill passage is disposed through the housing for placing the compression chamber in open flow fluid communication with a well annulus exterior of the housing so that well fluid may flow into the compression chamber as the apparatus is lowered into a well. An isolation valve is provided for selectively closing the fill passage and thereby trapping well fluid in the compression chamber. An operating element is disposed in the housing. An actuating piston is slidably disposed in the housing and is operably associated with the operating element for operating the same in response to movement of the actuating piston relative to the housing. The actuating piston and housing are so arranged and constructed that movement of the actuating piston relative to the housing changes the volume of the compression chamber and of any well fluid trapped therein.

Abstract: An improved presettable, pressure-responsive retrievable fluid control valve contains a plurality of spring housing sections having individual springs disposed therein. Each of the springs is connected in mechanical parallel with each other spring. To select the preset pressure threshold at which the valve opens in response to a column of fluid in a tubing in which the valve is disposed, the number of springs and zero to two compression spacer members are chosen for each spring. The valve also includes a bypass section having an inner bypass mandrel connected by a frangible member to an outer bypass port member. Connected to the outer bypass port member is a sealing member for seating the valve in a seating nipple of a tubing. The bypass mandrel and the outer bypass port member are normally held by the frangible member in a fixed relationship so that ports through the bypass mandrel and the outer bypass port member are axially offset in a closed, or non-fluid conducting, position.

Abstract: A safety valve having a flow tube telescopically movable in the housing for controlling the opening and closing of the valve in which the housing has a fluid chamber with a piston connected to the flow tube and a fluid passageway connected to the chamber adapted to be in communication with the fluid pressure at the well surface. A valve element and valve seat in the passageway seals off fluid flow through the seat and holds the flow tube in the open position when pressure is applied to the fluid passageway. Spaced minimum leak seals may be provided to form the fluid chamber. An antiburst communication line may be provided between the chamber and the bore of the safety valve having a check valve for equalizing pressure in the chamber. A valve mechanism operable by the flow tube shuts off the flow of fluid in the passageway to the fluid chamber when the valve closure member is in the open position.

Abstract: A tubing retrievable surface controlled subsurface safety valve having a rotatable ball-type flow closure element is disclosed. The ball element is rotationally operated and guided by a pair of guide members fixed in the valve by a stop ring. The guide members co-act with the ball to provide the desired rotational movement as well as providing a movement limit stop to prevent rotational overtravel of the ball. The tubular operator means imparts longitudinal movement to the ball greater than the predetermined movement required to effect the desired ball rotation prior to engaging the stop ring.A locking sleeve having a longitudinal locking movement greater than the predetermined movement to rotate the ball open is provided. Operating movement of the locking sleeve uncovers a control fluid port for operating a supplemental subsurface valve operably secured with the valve. Prior to activating the locking sleeve to install the supplemental valve, the valve may be controlled through either of two conduits.

Abstract: There are disclosed two embodiments of a subsurface safety valve having operating means which is responsive to the supply of control fluid from a remote source for holding a closure member in open position and which is retrievable separately from the closure member, so that with the bore of the mandrel above and below the closure member fluidly disconnected, the closure member automatically closes so as to close in the well when the operating means is so retrieved.

Abstract: A subsurface valve which functions as a lubricator valve and a retainer valve in response to changes in control pressure which may be pumped through to kill a well and which is provided with a lock means for locking the valve in closed position.

Abstract: A downhole well pump powered by pressurized fluid conducted to it through a power fluid conduit connected to its upper end by a remotely releasable connector which makes it possible to run and retrieve the pump either at the time the power fluid conduit is run or retrieved, or separately, and when run or pulled separately either through use of the conduit or other means such as wireline, rods, pipe, or the like, the connector being releasable simply by dropping a ball into the conduit and then building fluid pressure against the ball. Actuation of the connector to disconnect also opens a drain or equalizing passage in the pump automatically. The power fluid conduit being inside the well tubing makes it practical to install this pump in wells having casing of sizes insufficient to accommodate power fluid conduits exterior of the tubing. Installations and methods for their preparation are also disclosed. Gas lift valves may be used in the power fluid conduit, where the power fluid is gas.

Abstract: An annulus pressure responsive downhole tool includes a housing having a power piston slidably disposed therein. First and second pressure conducting passages communicate a well annulus with first and second sides of the power piston. A retarding device is disposed in the second pressure conducting passage for delaying communication of a sufficient portion of an increase in well annulus pressure to the second side of the power piston for a sufficient time to allow a pressure differential across the power piston to move the power piston from a first position to a second position relative to the housing. The retarding device is an annular floating shoe having a large number of O-rings frictionally engaging inner and outer tubular members of said housing.

Abstract: A cement staging apparatus for wells and including well casing, comprising an open ended hollow body having a number of spaced ports therethrough; a first hollow member slideably associated with said body and having a first ports closed position and a second ports open position; first pressure associated with said first member for displacing said first member and opening said ports thereby; a second hollow member slideably associated with said body and having a first ports open position and a second ports closed position and including shifting pressure relieving means associated with said body; second pressure means associated with said second member for displacing said second member and closing said ports thereby; said second member spaced a distance from said first member; said body, said member and said first pressure means defining a canister having an open end for receipt of a supply of pressurized cement and adapted for distributing said cement through said ports; and said body, said first and said seco

Abstract: The subterranean well safety valve useful in oil and gas wells employs a rotatable flapper to close a fluid production flow path. A through-the-flapper equalizing valve means is employed to equalize pressure across the closed valve in response to movement of an axially shiftable flow tube actuator. A spring-loaded poppet valve extends through the flapper on the periphery of the flapper in alignment with the end of the flow tube. The equalizing valve is opened upon initial movement of the flow tube followed by full opening of the flapper.

Abstract: A lubricator valve assembly comprises a reciprocably rotatable ball valve which is operated between open and closed positions solely through the selective application of control pressures and/or tubing pressure above the valve to a double acting sleeve type actuating piston. One end of the actuating piston has a valving piston formed thereon which cooperates with a seal bore in the housing to effect the opening or closing of a bypass fluid passage extending from a region below the ball valve to a region above the ball valve. Such valving piston also functions as part of a lost motion connection between the actuating sleeve piston and a reciprocable actuator for rotating the ball valve. In opening the ball valve, the valving piston first moves upwardly to establish a fluid bypass around the closed ball valve and then establishes contact with the actuator to rotate the ball valve to an open position.

Abstract: A surface controlled subsurface safety valve having rotatable ball-type closure elements and disclosed the tubular operator assembly is sealed to be substantially pressure balanced with respect to well fluid pressures when the ball-type closure is in either the open or closed position. Such arrangement enables the valve to be opened at a moderate control fluid pressure level with a substantial well pressure differential across the closed ball. In the disclosed tubing retrieval embodiment, an enclosed hydraulic system is used to balance the tubular operation and offset the hydrostatic head of the control fluid to enable greater setting depth.

Abstract: An equalizing annulus valve for use in controlling flow in the annulus between two tubular conduits in a subterranean oil or gas well has a control pressure responsive main valve piston and a booster piston for closing radial flow ports. The booster piston is spring loaded relative to the main piston and excess annulus pressure below the valve acts on the booster piston rather than on the main piston. The main piston can be partially opened before abutting the booster piston to permit pressure below the valve to meter through an equalizing port in the main piston and through the main flow ports. When the pressure is equalized, the main piston and booster piston can be shifted to a fully open position. An auxiliary piston responsive to an increase in annulus pressure can also be used to shift the main piston.

Abstract: In accordance with an illustrative embodiment of the present invention, a surface controlled subsurface safety valve system includes a tubing retrievable safety valve having a valve element that is opened and held open in response to the pressure of a control fluid in a control line and automatically closed when control pressure is reduced, and means for equalizing the pressure of fluids above and below said valve element to aid in reopening the same after closure, including a wireline retrievable equalizing valve removably installed in the pocket of a side pocket mandrel that is connected in the tubing above said safety valve, said equalizing valve being arranged to be opened and closed in response to changes in the pressure of said control fluid. A uniquely constructed side pocket mandrel also is disclosed.

Abstract: Pressure equalizing means for well tools having a tubular housing and an operator tube movable longitudinally therewithin, there being provided a valved bypass passage in the housing and a shoulder on the operator tube for engaging and opening the valve of the valved bypass passage upon longitudinal movement of the operator tube in the housing, the equalizing mechanism further including a pair of seal rings sealing between the housing and the operator tube above and below the valved bypass passage in the housing and a lateral passage in the wall of the operator tube normally above the pair of seals but movable under no-flow conditions with the operator tube to a position between the pair of seals prior to the operator tube shoulder contacting the valve of the bypass passage, thus avoiding damage to or flow cutting of the seals which normally form a secondary seal to provide bubble-tight integrity even if the valve in the bypass passage does not seal bubble tight.

Abstract: A surface controlled subsurface safety valve having a ball type valve closure. The ball member and its associated components are protected from damage by preventing excessive control fluid pressure from applying force to the ball member. Also, rotation of the ball member is prevented until any difference in pressure across the ball member and its seating surface has decreased below a preselected safe value.

Abstract: A flow tester valve apparatus includes a housing having a flow passage disposed therethrough with a flow valve disposed therein for opening and closing the flow passage. A power mandrel is disposed in the housing and includes a power piston. The power mandrel is operatively associated with the flow valve for moving the flow valve from its closed position to its open position. A power port transmits pressure from a well annulus to a first side of the power piston. A first chamber is disposed in the housing and filled at least partially with a compressible liquid and a second side of the power piston is in fluid communication with the first chamber. A second chamber is disposed in the housing and includes a floating piston which divides the second chamber into a first zone and a second zone. An equalizing port is disposed in the housing for transmitting pressure from the well annulus to the second zone of the second chamber.

Abstract: A well safety valve for controlling the fluid flow through a well tubing in which at least one piston having a small cross-sectional area for reducing the effect of high hydrostatic forces controls the opening and closing of the valve. The piston has a piston rod extending upwardly from the piston for connection to the tubular member controlling the valve whereby the piston and piston rod are acted on in tension by hydraulic control fluid and avoids subjecting the small piston to compression loads. A stop is provided on the piston on the side remote from the upwardly extending piston rod for preventing compression loading on the piston in the event the tubing pressure is greater than the control fluid pressure. The connection between the piston rod and the tubular member includes at least one telescopically movable elongate member having a greater cross-sectional area than the piston rod and is connected between the piston rod and the tubular member.

Abstract: A flow tester valve apparatus includes a housing having a flow passage disposed therethrough with a flow valve disposed therein for opening and closing the flow passage. A power mandrel is disposed in the housing and includes a power piston. The power mandrel is operatively associated with the flow valve for moving the flow valve from its closed position to its open position. A power port transmits pressure from a well annulus to a first side of the power piston. A first chamber is disposed in the housing and filled at least partially with a compressible liquid and a second side of the power piston is in fluid communication with the first chamber. A second chamber is disposed in the housing and includes a floating piston which divides the second chamber into a first zone and a second zone. An equalizing port is disposed in the housing for transmitting pressure from the well annulus to the second zone of the second chamber.

Abstract: In accordance with an illustrative embodiment of the present invention, a pressure controlled well tester apparatus having a full-bore ball valve closure element includes valve actuator means responsive to changes in the pressure of fluids in the well annulus for moving the ball valve between its open and closed positions, and bias means responsive to the hydrostatic pressure of fluids in the well bore for assisting in moving the ball valve to its fully closed position.

Abstract: A surface controlled subsurface safety valve for deep well service. Communication of control fluid to the subsurface safety valve is controlled by a pilot valve at a subsurface location in close proximity to the safety valve. Responsiveness of the subsurface safety valve to decrease in control fluid pressure is thereby increased and the safety valve's closure speed is also increased. The pilot valve controllably communicates pressurized control fluid to open the safety valve and allows control fluid to be displaced into the flow path through the safety valve during valve closure.

Abstract: An annulus pressure responsive tester valve including a pressure assisted isolation valve which includes a pressure differential metering cartridge to control the rate at which the isolation valve returns to the fluid pressure in the annulus between the wellbore and testing string thereby continuously controlling the rate of expansion the inert gas within the gas chamber and the attendant operation of the tester valve regardless of any temperature effect by cold fluids pumped therethrough.

Abstract: A single control line, surface controlled subsurface safety valve for controlling flow in a well, having a valve closure member responsive to the longitudinal movement of an operator tube disposed in the bore of the safety valve. The operator tube is moved to a position opening the valve closure member by action of a piston, housed in an annular pressure zone, which is responsive to control fluid pressure from the surface of the well. The operator tube is returned to a position closing the valve closure member by action of a resilient urging means housed in an annular chamber located above the annular pressure zone. There is no pressure differential between the bore of the safety valve and the annular chamber housing the resilient urging means.

Abstract: An annulus pressure responsive tester valve including a pressure assisted isolation valve which includes a pressure differential metering cartridge to control the rate at which the isolation valve returns to the fluid pressure in the annulus between the wellbore and testing string thereby continuously controlling the rate of expansion the inert gas within the gas chamber and the attendant operation of the tester valve regardless of any temperature effect by cold fluids pumped therethrough.

Abstract: A method and apparatus are provided for effecting the automatic closing of the bore of a subterranean well conduit upon the withdrawal of a tubular work string or production string from the conduit and the reopening of such bore upon the reinsertion of a tubular string. A biased shiftable valving element is held in an open position by an actuator sleeve which is operatively connected to an inserted tubular string so as to move with such string only a limited distance during either the insertion or the withdrawal movement thereof and permits the valving element to close when the inserted tubular string is withdrawn to prevent fluid remaining in the well from draining into the formation.

Abstract: The disclosure relates to a flapper type safety valve incorporating a pressure equalizing feature in the body of the flapper valve. A bypass aperture in the flapper valve communicates with a downwardly facing conical sealing surface. A conically shaped sealing plug is insertable in the bypass aperture and has a post portion projecting upwardly through such aperture. A diametral slot is provided in the top surface of the flapper valve body to mount a leaf spring which is secured to the upstanding post. An abutment element is also secured to the top end of the upstanding post and projects diametrically into the path of the actuating sleeve normally utilized to effect the opening of the flapper valve.

Abstract: A valve used in a drill stem test tool has a ball movable between an open position to allow flow through the drill string for testing and a closed position to block flow. Operating means move the ball between the open and closed positions in response to pressures in the well annulus. A nitrogen filled pressure chamber and pressure balancing piston compensate for variations in annular pressure as the tool is being lowered into position in the well. Actuating means including a weight operated sleeve are operated from the surface to overcome the compensating effect of the pressure balancing piston to allow the ball to be rotated to the open position. The ball is spring biased toward the closed position by a coil spring located inside the pressure chamber. Relieving pressure in the annulus causes the spring to close the ball.

Abstract: A ball valve is turned relative to its seat by means of three concentric sleeves mounted within a housing bore. Pins carried by the middle piston sleeve extend outward into slots in an outer carrier sleeve and inward into cam grooves in the outer wall of an inner drive sleeve. Axial movement of the middle sleeve under hydraulic pressure causes turning movement of the inner sleeve which then drives through bevel gears to turn the ball valve. The parts are constructed so that hydraulic forces within the housing acting to hold the ball valve in closed position against its seat are substantially balanced by forces in the opposite direction acting against the outer sleeve.

Abstract: A well safety valve, connectable in a tubing string for controlling fluid flow therethrough, in which the valve closure means is operated by a longitudinally movable, telescoping tubular operating member. High differential pressure across the closed valve closure means causes the tubular operator to telescope preventing damage to the closure means. The telescoping tubular operator extends automatically upon release of the high differential pressure. A piston rod type equalizing valve is provided which is engageable with the tubular operator in order to reduce pressure differential across the closure means prior to closure member opening forces being applied to the closure member by the tubular operator.

Abstract: In a well safety valve for controlling the fluid flow through a well conduit in which the valve has a housing and a flow tube controlling a valve element, the improvement in means for opening and closing the valve. A gas chamber is positioned in the housing with a fluid passageway positioned between the gas chamber and a port for receiving fluid pressure from the well surface for increasing the pressure of the gas in the chamber. One or more pistons are movably positioned in the passageway between the gas chamber and the port with the pistons restricting but allowing fluid flow through the passageway. The pistons are connected to the flow tube whereby when pressure on the port side of the pistons is reduced compressed gas in the gas chamber will act on the fluid in the gas chamber side of the piston to move the pistons in a direction to close the valve. A check valve may be in parallel with the pistons for quickly pressuring the gas chamber.

Abstract: A lubricator valve apparatus adapted for use when running wireline tools into an offshore well during a production test of the well. The valve includes a valve body having a central flow passage and a ball valve element for opening and closing the passage, hydraulically operable means responsive to surface-controlled pressure for opening and closing the ball valve, latch means for releasably holding the ball valve in both the open and the closed positions, and bypass valve means for equalizing pressures across the ball valve prior to opening thereof and arranged in response to pressure applied at the surface to the production pipe to be opened to provide a flow path for well control fluids.

Abstract: A safety valve for the production tubing of wells and/or fluid flow lines includes a valve element having both linear and rotary components of movement within a valve body and is actuated by a lost-motion rack and pinion gear actuating mechanism. The clam-shell pinion gear is moved linearly within the valve body by a hydraulic sleeve piston actuator for inducing valve movement responsive to hydraulic control of the sleeve piston. The sleeve piston is also responsive to upstream pressure for pressure actuation of the valve to its closed position. The valve element is also mechanically movable to its closed position. To facilitate opening movement of the valve, after an initial part of the opening movement of the sleeve piston assembly has occurred, pressure upstream of the valve element is communicated with the downstream side of the valve element, thus balancing pressure across the valve element and dissipating any pressure induced resultant forces that oppose valve opening movement.

Abstract: A single line surface controlled, subsurface safety valve, adapted for connection in a well tubing string. The safety valve has a closure means disposed in the bore of the safety valve housing and is operable by action of control pressure fluid causing a longitudinal operator to move the closure means to an open to flow position. The control pressure fluid chamber in the safety valve is protected from well pressure by providing annular areas, between the longitudinal operator and the housing, positioned between the control pressure fluid chamber and well pressure. The annular areas are sealed from exposure to well pressure and are in fluid communication with each other. A floating piston is positioned to respond to well pressure entering the annular areas and thus move to engage and assist the operator means in closing the safety valve to flow of well fluids therethrough. Vent means is provided to prevent a hydraulic lock from retarding movement of the floating piston.

Abstract: A subsea test valve system for well completed at the floor of the sea includes a safety valve and disconnect mechanism mounted in a blowout preventer at the bottom of the sea and having hydraulic fluid pressure operated means for opening the safety valve and controlling a latch in the disconnect mechanism. A tubing test string shut off valve is releasably latched in the disconnect mechanism and has a hydraulic fluid operated shut off valve and a valve for venting the test string to the riser pipe which extends from the blowout preventer to the vessel or platform at the surface of the sea. The subsea hydraulic pressure operated devices are supplied with pressure fluid from a subsea accumulator under the control of subsea pilot valves which are operated by small pressure differences, to accomplish rapid operation at great depth from a control console on the vessel or platform.

Abstract: A reverse circulation valve includes a cylindrical housing having an open longitudinal passageway disposed therethrough and a circulating port and a power port disposed through a wall thereof. A valve mandrel is slidably received in the housing and movable from a closed position closing the circulating port to an open position opening the circulating port. The valve mandrel includes an annular piston received in the housing for moving the valve mandrel from its closed position to its open position. The power port communicates the piston with a pressure exterior of the housing. A frangible restraining structure is located between the valve mandrel and the cylindrical housing for restraining movement of the valve mandrel from its closed position to its open position until the pressure exterior of the housing exceeds a predetermined value, and for frangibly releasing the valve mandrel when said pressure exterior of the housing exceeds said predetermined value.

Abstract: A drill pipe tester valve includes a spherical valve member supported from an upward facing surface of a housing so that downward forces exerted on the valve member in its closed position, due to fluid pressure in a string of pipe above the valve member, are transmitted substantially entirely to said housing.

Abstract: A pressure insensitive, fail-safe subsea valve is disclosed. The valve is manipulator operable for deep water application and does not require conventional diving techniques to install, maintain or remove. The valve is pressure balanced by employing a hollow valve stem which equalizes the pressure on both ends of the stem.

Abstract: Subsurface apparatus and method for using same in a hydrocarbon producing well to enable retrieval of a full opening subsurface safety valve mounted in the well tubing without disturbing the major portion of the well tubing located below the safety valve. The apparatus includes a subsurface tubing hanger below the safety valve from which the major portion of the well tubing is suspended and through which tubing the hydrocarbons flow to the surface. Disposed above the safety valve is a tubing holddown apparatus and a controllable safety joint. The holddown apparatus provides a lower anchor for the portion of the tubing disposed above the tubing hanger and the stinger which is received in and seals with the tubing hanger.

Abstract: An equalizing ball valve member and valve apparatus for use in a tubing string in a well bore of an oil or gas well to isolate a lower portion of the well bore below a packer including a body having a longitudinal bore therethrough connectible in a well tubing string, a lower annular valve seat supported in the body for limited sliding movement, fluid seal means between the lower valve seat and the body, an upper annular valve seat supported in longitudinal spaced relation from the lower valve seat within the body, an equalizing ball valve member supported for rotation between opened and closed positions between the valve seats, pivot members secured with the ball valve member for rotating the valve member, and a longitudinally movable operator member coupled with the pivot members for moving the pivot members longitudinally while permitting the members to traverse an arcuate path as the ball valve member rotates between an open and closed positions.

Abstract: A well safety system comprising a tubing retrievable safety valve adaptable for being connected in a well tubing string with means therein, responsive to pressure, for opening and closing the valve. The tubing retrievable safety valve is to be connected, in the tubing string, below a landing nipple for receiving a secondary safety valve. The safety valve and landing nipple are connected by a common conduit for conducting a suitable pressure fluid for control and balance of the safety valve and a secondary valve landed in the landing nipple. Means are provided on the landing nipple for selectively flushing pressure fluid into the tubing bore. This abstract of the disclosure is neither intended to define the scope of the invention which, of course, is measured by the claims nor is it intended to limit the invention in any way.

Abstract: In a well safety valve for controlling the fluid flow through a well conduit in which the valve has a housing and a tubular member controlling a valve element the improvement in means for opening and closing the valve. At least one piston is telescopically movable within and has its longitudinal axis within the wall of the housing and outside of the tubular member and engages the tubular member. The first side of the piston is in communication with a hydraulic passageway adapted to extend to the well surface for opening the valve. The second side of the piston extends into a closed gas chamber tending to move the valve to the closed position. The piston has a small cross-sectional area for reducing the pressure effect in the gas chamber of the gas caused by movement of the second side of the piston whereby the differential between the opening and closing forces are reduced thereby allowing the valve to be used at greater depths in the well.

Abstract: A check valve is provided for use in the tubing string of a fluid producing well. The check valve is removably seated within the restricted diameter of a seating nipple in the tubing string. Resilient holddown means at the base of the valve are provided for this purpose. The check valve comprises a hollow generally tubular body having a pierceable valve element positioned therein, the valve opens and closes in response to fluid pressures bearing thereon. To equalize the pressures above and below the valve the pierceable valve element may be ruptured by a conventional wireline spear, allowing the fluid to drain slowly through the valve.

Abstract: Disclosed is a tubing retrievable surface controlled subsurface safety valve having provisions for blocking communication of control fluid to the valve's pressure responsive operator and for locking the valve open in the event of valve failure. This abstract of the disclosure is neither intended to define the scope of the invention which, of course, is measured by the claims nor is it intended to limit the invention in any way.

Abstract: A lubricator valve apparatus adapted for use when running wireline tools into an offshore well during a production test of the well. The valve includes a valve body having a central flow passage and a ball valve element for opening and closing the passage, hydraulically operable means responsive to surface-controlled pressure for opening and closing the ball valve, latch means for releasably holding the ball valve in both the open and the closed positions, and bypass valve means for equalizing pressures across the ball valve prior to opening thereof and arranged in the event hydraulic control of the ball valve is lost to be opened in response to pressure applied at the surface to the production pipe to provide a flow path for well control fluids.

Abstract: Disclosed is a surface controlled subsurface safety valve adapted to be landed in a dual line landing nipple. The safety valve is used to control well fluids conducted through the bore of a well tubing string. The valve has a control fluid pressure chamber and a balance pressure chamber along with a zone in the valve exposed to balance fluid pressure. The control fluid pressure chamber is interspersed between the balance fluid pressure chamber and the balance pressure zone, and has a system of seals associated therewith, that provide a fail-closed safety system. Tubing bore pressure, in the event of seal failure, enters the balance pressure chamber, causing the safety valve to close. This abstract of the disclosure is neither intended to define the scope of the invention which, of course, is measured by the claims nor is it intended to limit the invention in any way.

Abstract: Disclosed is a surface controlled subsurface safety valve for deep well service. Communication of control fluid to the subsurface safety valve is controlled at a subsurface location in close proximity to the valve. Responsiveness of the subsurface safety valve to decreases in control pressure is thereby increased and the valve's closure speed is also increased. This abstract of the disclosure is neither intended to define the scope of the invention, which, of course, is measured by the claims, nor is it intended to limit the invention in any way.

Abstract: In a well safety valve for controlling the fluid flow through a well conduit in which the valve has a housing and a valve element movable in the housing between an open and closed position for controlling the flow through a passageway in the housing and means for biasing the valve element to a closed position, the improvement in piston means for moving the valve element into an open position. A piston is telescopically mounted in the housing, is controlled by fluid from the well surface, and is offset from the passageway. The piston has a small cross-sectional area for reducing the effect of hydrostatic forces acting on the piston whereby the valve may be used at greater depths in the well. The piston has a diameter smaller than the diameter of the valve passageway for ease of manufacture and less expense. Preferably the piston is positioned within the wall of the housing, and may be a solid cylinder or may be tubular one outside diameter with a second lower section of a greater outside diameter.

Abstract: Disclosed is a surface controlled subsurface safety valve wherein the greater of well pressure and balance pressure assists in closing the safety valve. Well pressure assist for valve closure is obtained without creating additional depth sensitive limitations as the balance pressure approaches zero. Balance pressure assist for valve closure is obtained without well pressure tending to maintain the valve open. This abstract is neither intended to define the scope of the invention, which, of course, is measured by the claims, nor is it intending to be limiting in any way.