Abstract: Pressure control in an isolated lower wellbore annulus, defined by a conduit sealably positioned within an isolated lower wellbore segment, is achieved while gravel packing by sensing the pressure within the isolated lower annulus while gravel packing and admitting fluid from the isolated lower annulus into the conduit at one or more discrete locations along the conduit when the sensed pressure corresponds to one or more threshold pressure conditions. The annulus pressure is sensed while gravel packing using a pressure-sensitive device disposed in the annulus, e.g., positioned by the conduit at a high-pressure location. The pressure-sensitive device actuates one or more valves carried along the conduit to admit fluid from the annulus into the conduit at one or more of the discrete locations, and thereby control the pressure in the isolated lower annulus.

Abstract: A method and a device for controlling a downhole hydraulic sequential control system (1) in which a number of pressure relief valves (20, 22) are arranged to open sequentially directly or indirectly for corresponding actuators (26, 34) through introduction of a hydraulic fluid, wherein the pressure of working fluid supplied to the control system is transmitted to hydraulic fluid in the control system (1). The pressure transfer may be effected by means of a dividing piston (6).

Abstract: A control system for a plurality of devices including a plurality of devices in at least one group. A first control line is in operable communication with the plurality of devices. A second control line in operable communication with the at least one group. A step-advance mechanism is in operable communication with each of the plurality of the devices, each mechanism being distinct from each other mechanism within the group of devices. Further disclosed herein is a method for reducing the number of control lines needed to control a plurality of downhole devices including supplying a first control line in operable communication with a plurality of devices including at least one group of devices and supplying a second control line in operable communication with the at least one group.

Abstract: A fluid loss device including a flapper and seat assembly that provide a seal on a lower flapper surface when the flapper is closed and resists pressure in either direction. The flapper and seat assembly is spring biased to contact a flapper support above the flapper to resist deformation of the flapper due to a pressure differential from below the flapper. The flapper and seat assembly may be moved by tubing pressure to release an opening prop that opens the flapper. The valve seat may include an elastomeric seal element to improve the fluid flow restriction. The flapper and seat assembly is also biased upward by a pressure differential from below to above the flapper, to thereby increase the flapper to valve seat pressure as the fluid pressure differential increases.

Abstract: A direct proportional control system for remotely controlling actuation of a tool. A well control system includes an actuator for a downhole well tool, the actuator including an actuator member which displaces to operate the well tool. A control system member is positioned at a remote location. A displacement of the control system member is proportional to a displacement of the actuator member.

Abstract: A method and apparatus for actuating a downhole tool is provided. The apparatus of the present invention includes a remotely energized actuator device that facilitates storage of energy needed to actuate a downhole tool after the device is placed downhole. By energizing the tool downhole, surface exposure to potential safety hazards is reduced.

Abstract: A method of isolating a reservoir of production fluid in a formation comprises providing a pair of valves (14, 16) in a bore intersecting a production formation and in which the hydrostatic pressuer in the bore at the formation is normally lower than the formation pressure, and then ontrolling the valves (14, 16) from surface such that the valves (14, 16) will only move from a closed configuration to an open configuration on experiencing a predetermined differential pressure across the valves.

Abstract: A hydraulic control and actuation system for downhole tools. In a described embodiment, a hydraulic control and actuation system includes an internal chamber serving as a low pressure region and a well annulus serving as an energy source. A valve assembly provides selective fluid communication between alternating opposite sides of a piston and each of the energy source and low pressure region. Displacement of the piston operates a well tool. Operation of the valve assembly is controlled via telemetry between a remote location and an electronic circuit of the system.

Abstract: Methods and apparatus for utilizing a downhole deployment valve (DDV) to isolate a pressure in a portion of a bore are disclosed. Any combination of fail safe features may be used with or incorporated into the DDV such as redundant valve members, an upward opening flapper valve or a metering flapper below a sealing valve. In one aspect, a barrier or diverter located in the bore above a valve member of the DDV permits passage through the bore when the valve member is open and actuates when the valve member is closed. Once actuated, the barrier or diverter either stops or diverts any dropped objects prior to the dropped object reaching and potentially damaging the valve member. In another aspect, the tool string tripped in above the DDV includes an acceleration actuated brake that anchors the tool string to a surrounding tubular if the tool string is dropped.

Abstract: The invention relates to downhole wellbore apparatus and particularly, but not exclusively, to apparatus for use in wellbore cleaning operations. A downhole tool (2) comprises a body (4) having a bore extending longitudinally therethrough, wherein the tool (2) further comprises a one-way valve (24,26) for allowing a flow of fluid in a first direction through the tool bore and preventing a flow of fluid in a second direction through the tool bore, the second direction being opposite to the first direction. The tool further comprises mandrel (38) for rendering the one-way valve (24,26) inoperable so as to be ineffective at preventing fluid flow; and a shear pin assembly (44,40) for selectively making the one-way valve operable so as to be effective at allowing fluid flow in the first direction and preventing fluid flow in the second direction.

Abstract: The present invention is directed to a system for controlling a hydraulic actuator, and various methods of using same. In one illustrative embodiment, the system comprises a first hydraulic cylinder, an isolated supply of fluid provided to the first hydraulic cylinder, the isolated supply of fluid positioned in an environment that is at a pressure other than atmospheric pressure, an actuator device coupled to the first hydraulic cylinder, the actuator device adapted to drive the first hydraulic cylinder to create the sufficient pressure in the fluid, and at least one hydraulic line operatively intermediate the first hydraulic cylinder and the hydraulic actuator, the hydraulic line supplying the sufficient pressure in the fluid to the hydraulic actuator in the remote locale.

Abstract: A back pressure valve assembly for use in a well casing string. The valve assembly comprises a housing with a stationary and a floating plate therein. The floating plate is moveable between an open position spaced from the stationary plate and a closed position engaging the stationary plate. Fluid flow downwardly through the valve assembly tends to move the floating plate toward the open position, and fluid flow upwardly through the valve assembly tends to move the floating plate toward the closed position. A finger or key may be used to prevent rotation of the floating plate with respect to the housing.

Abstract: A control system for use in controlling actuation of tools in a subterranean well. In a described embodiment, a control system includes a well tool, an actuator for the well tool and a control module interconnected between the actuator and first and second fluid lines. The control module is operative to meter a predetermined volume of fluid from the actuator to the second line in response to pressure applied to the first line.

Abstract: A simple debris removal apparatus for use in a wellbore. In one aspect of the invention a modular, interchangeable venturi is provided which can be retrofit into an existing debris bailer having a filter and a debris collection container. In another aspect of the invention, a venturi is utilized to create a negative pressure in a wellbore sufficient to actuate a retrieval tool for a downhole device. In yet another aspect of the invention, a combination tool is provided which can evacuate debris in a wellbore, thereby uncovering a downhole device which can then be removed in a single trip. In yet another aspect of the invention, a debris removal apparatus is provided with a method for utilizing the apparatus in a wellbore on coiled tubing.

Abstract: An interventionless bi-directional barrier device of a downhole tool for use in a wellbore and a method of utilizing the barrier device to control the flow of production fluids in the wellbore are described herein. The barrier device includes a flapper mechanism having first and second flappers articulably linked together and articulably linked to a base member that is slidable within the downhole tool. The flapper mechanism provides a seal between opposing uphole-and downhole ends of the downhole tool upon actuation thereof. The method of controlling the flow of production fluids in the wellbore includes closing the barrier device to block flow through the tool, supporting the barrier device from a pressure exerted from a first direction, and supporting the barrier device from a pressure exerted from a second direction.

Abstract: A method and apparatus for selectively actuating a dual check valve assembly within a well for a direct circulating operational mode or a reverse circulating operational mode. A tubular housing which may be connected to well tubing is provided with a check valve assembly and may be provided with a rotatable J-slot mode indexing sleeve having an internal J-slot geometry. An inner tubular member which also may be connected to well tubing is linearly movable within the tubular housing to a valve open position, an indexing position and a valve enabled position being controlled by the J-slot geometry of the J-slot indexing sleeve or being controlled by moving the inner tubular element and resisting movement of the tubular housing. Relative positioning of the inner tubular member and the tubular housing to selective valve mode positions may also be achieved responsive to fluid flow, by mechanical compression, or by motion operation.

Abstract: A method and apparatus for causing pressure variations in a wellbore. A valve mechanism and a sealing device are provided in the wellbore. The valve mechanism is part of a valve device which may be actuated between an open position and a closed position. The valve device is actuated to the closed position to allow an increase in pressure below the sealing device and is actuated to the open position to allow a fluid to pass through the valve device up the wellbore. The valve device is alternately actuated between the closed position and the open position to cause cyclical pressure variations in the wellbore below the sealing device. The valve device includes the valve mechanism, a fluid passage, a control mechanism for controlling the valve mechanism, and a delay mechanism for delaying the actuation of the valve device from the open position to the closed position.

Abstract: An oscillating valve driven by the pressure in a mud pulser develops a pressure variation in the mud pulse signal that is at a frequency that is different than the frequencies of the mud system. The oscillating valve is coupled to or integral with the pulse drive cylinder, whether the drive means for operation of the pulser is upstream or downstream from the orifice, or whether or not the drive means and the poppet are on the same side or opposite sides of the orifice. The oscillating valve is a bistable valve which preferably forms one wall of the drive piston of the pulser. Pressure from the drive cylinder behind the drive piston is directed in such a way as to unseat the bistable valve. When the bistable valve unseats, pressure is bled from within the drive cylinder, which also bleeds the pressure that unseated the bistable valve in the first place.

Abstract: A method and apparatus for obstructing the passage of fluid within a fluid flow conduit and subsequently reconfiguring the tool to allow substantially full-bore passage therethrough. Pressure developed upstream of the obstruction can be utilized to operate pressure actuated tools such as liner hangers. Equipment used in subsequent wellbore operations such as drill pipe darts can pass undamaged through the opened port. In an embodiment, the flow through a tubular is obstructed by placing a ball on an expandable ball seat, developing a pressure differential across the ball seat, equalizing the pressure after the hydraulically actuated tool completes its function, and mechanically manipulating the drill string to open the expandable ball seat and allow the ball to pass through.

Abstract: The phase of this process is done by the functionality of the perforated lower stem, which due to the fact that its internal conduit is able to connect the lower bellow in an alternated way, first to the tubing and after, to the casing. This is possible due to the fact that it is assisted by: a) a window that communicates the casing with the tubing when the lower bellow is open, and b) sealing packing installed in the lower stem to isolate the casing pressure, in order that the lower bellow can register only the tubing pressure when it is in closing position.

Abstract: The present invention provides for a tool having diverter valves to reduce the pressure in a wellbore caused by frictional resistance to fluid flow as the beta wave of a gravel pack operation makes its way up the wellbore.

Abstract: According to the present invention, the flow-activated valve assembly is a fluid-driven tool for use in various down hole drilling and fishing operations, which is activated by the introduction of fluid into an enclosed assembly, whereby fluid forces a movable portion of such assembly to slide until it engages a stationary portion, where an impact is realized, and at which time the fluid is permitted to exhaust. Upon this impact, another valve is opened to permit fluid to flow in another channel, moving the assembly in the opposite direction until it reaches a second stationary portion, at which point another impact is realized in the opposite direction. This creates a bi-directional hammering effect for each cycle of the tool, which can be utilized in various applications, either for the jarring effect, the linear motion, or a combination of both.

Abstract: A multi-zone packing system having unique features that allow for remote operation, thereby eliminating the need to raise and lower a work string and crossover tool to various zones of interest during a frac pack, gravel pack or related completion procedure. The squeeze pack system has a crossover tool or port collocated with each zone of interest and remotely operated closing devices to allow for the setting of each packer and the packing job to be performed with minimal or no movement of the work string.

Abstract: A by-pass valve mechanism for a well treatment tool having at least one flow sensitive element, permitting by-pass of well fluid past the flow sensitive element of the well treatment tool during conveyance of the well treatment tool to treatment depth within a well. A valve housing adapted for connection with a well tool defines an internal flow passage and has at least one by-pass port communicating well fluid between the flow passage of the service tool and the annulus between the well casing and the service tool. A sliding sleeve valve element is normally secured at its open position by shear elements permitting flow of well fluid through the and is moveable between an open position diverting fluid flow from within the service tool to the annulus and a closed position blocking the flow of well fluid through the by-pass port. The sleeve valve element is released and automatically closed by predetermined hydrostatic tubing or casing pressure or pump pressure.

Abstract: The present invention relates to downhole apparatus and particularly but not exclusively, to multi-cycle circulating subs used during downhole drilling operations. Apparatus is provided comprising a piston (42) slidably mounted in a body (4) between positions in which at least one aperture (40) in the body is opened and closed. Movement of the piston (42) is controlled by a pin (86) secured to one of the body and a control member, and a control groove (52) in which a portion of the pin is received formed in the other of the body and control member. An arrangement of elements (32, 76) respectively connected to the control member and body is such that, as the control member moves axially, increasing lengths of said elements locate adjacent one another so as to provide resistance to relative rotation in at least one direction of the control member and body. The relative rotation is rotation which presses the control member against the control groove.

Abstract: A method and apparatus for actuating a downhole tool is provided. The apparatus of the present invention includes a remotely energized actuator device that facilitates storage of energy needed to actuate a downhole tool after the device is placed downhole. By energizing the tool downhole, surface exposure to potential safety hazards is reduced.

Abstract: A pressure control system for a wet connect/disconnect hydraulic control line connector includes a reservoir and a piston in said reservoir. The reservoir contains hydraulic fluid or equivalent and the piston is biased by hydrostatic pressure or an atmospheric chamber and hydrostatic pressure. Pressure in the hydraulic line being controlled by the system is controllable based upon the existence or lack of an atmospheric chamber and its placement. The method for controlling pressure in a hydraulic control line wet connector includes running the control system and biasing the piston to control pressure.

Abstract: A system and methods for proportionally controlling hydraulically actuated downhole flow control devices using derived feedback control. The system comprises a downhole flow control device with a moveable element in a stationary housing. The moveable element is actuated by a balanced hydraulic piston. Hydraulic lines are fed to either side of the piston to effect actuation in either direction. A processor controlled, surface mounted hydraulic system supplies fluid to the piston. A pressure sensor measures supply pressure to the piston and a cycle counter indicates pump cycles and both sensors generate outputs to the processor. The downhole moveable element is cycled between end stops until successive moveable element breakout pressures are within a predetermined value as measured by the surface pressure sensor. A relationship is then derived between moveable element movement and pumped fluid volume and the relationship is used to move the moveable element to a predetermined position to control flow.

Abstract: A flow responsive dump valve mechanism for a straddle packer tool and has a valve controlled flow passage from which underflushed fluid, typically well treatment slurry, in a conveyance and fluid supplying tubing string can be dumped into a well casing. The dump valve mechanism incorporates a ratcheting power piston, an indexing mechanism and high and low load energy storage systems to accomplish open, closed and intermediate dump valve positions. The intermediate position increases the functionality of the tool by preventing accidental closure either due to the free fall of fluid through the coiled tubing or during flushing of the tool and permits the flow rate to be increased for thorough cleaning of the straddle tool and coiled tubing. For energy storage, a light compression spring provides power to cycle the indexing mechanism. Heavier load disc springs (Bellville Washers) are used to provide power for the ratcheting power piston to open the valve.

Abstract: Apparatus for a one trip completion of fluid production wells. A completion tool string includes a pressure activated cementing valve, an external casing packer, a pressure activated production valve, an opening plug and a plug landing collar and a closing plug and seat. This tool series is assembled near the end of a production tube string upstream of the well production screen.

Abstract: A system of valves is disclosed wherein said valves operate over a designated pressure interval and are arranged to actuate performance of a sequenced set of events by downhole tools with the application of pressure to said valves.

Abstract: A flow completion system comprises a tubing spool which is connected above a wellhead housing, a tubing hanger which is supported in the tubing spool and which includes an axial production bore and at least two conduits that each extend from the bottom of the tubing hanger to either the top or the outer diameter of the tubing hanger, and a gate valve assembly which includes an elongated body having a longitudinal bore extending therethrough, a plurality of gates slidably disposed in the longitudinal bore across respective flow passages which each extend laterally through the body between corresponding inlet and outlet ports, each gate being movable between an open position wherein an opening in the gate is aligned with its respective flow passage and a closed position wherein the opening is offset from its respective flow passage, an actuator for moving the gates simultaneously between a first position, wherein at least one of the gates is in its open position, and a second position, wherein the at least one

Abstract: An actuator uses a gas absorptive material to produce displacement of a member of the actuator. In a described embodiment, an actuator includes a metal hydride powder. When the powder absorbs hydrogen gas, it expands and displaces a piston. When the powder discharges hydrogen gas, the powder contracts, displacing the piston in an opposite direction. Various methods of controlling gas absorption and discharge are provided.

Abstract: A device for providing surge pressure reduction with volume compensation and methods of use are presented. Surge pressure reduction and volume compensation are accomplished by pressure-actuated release of the compensation device.

Abstract: A tubing hanger to facilitate production tubing annulus access including a tubing hanger body having a central bore, a shuttle valve slidably mounted to the tubing hanger body, and at least one annulus access bore through the tubing hanger permitting fluid communication between the central bore and an annulus defined between a production tubing string and a wellbore or casing via the tubing hanger body and the shuttle valve. The shuttle valve may be slidingly movable between an open and a closed position. The tubing hanger may further include a groove enclosed by a filler, the groove providing communication between a plurality of small annulus access bores and a large annulus access bore.

Abstract: Bypass valve for use in wellbores, particularly during the setting of hydraulic anchor packers, a bypass valve is provided with a body (4) incorporating a wall provided with at least one opening (20) and a piston (30) slidably mounted and having a longitudinal bore extending therethrough. The piston (30) is movable between a first position, in which the bore of the piston (30) is substantially isolated from the exterior of the body (4), and a second position in which a passage is provided from the bore of the piston (30) to the exterior of the body (4). Constraining means (42, 52) prevent movement of the piston (30) from the first to the second position. Overriding means are provided to permit movement to the second position.

Abstract: A unitary, forward buckling rupture disc is provided that is adapted to be mounted in a holder in which the disc is in closing relationship to a tubing string in an oil well and has greatest utility for testing the integrity of the connection between the sections of oil well tubing strings. The disc is designed to withstand the fluid pressure head in the string and a leak test pressure, and to then burst and fully open under a predetermined overpressure. The concavo-convex bulged section of the disc has a non-circular, continuous score line formed in the concave face thereof. The score line is of continuously varying depth around its circumference and includes an outwardly projecting cam segment which is of greatest depth that ruptures first and is in direct opposition to a lesser depth score line portion forming a hinge area for the burst region of the disc.

Abstract: The present invention generally relates to a valve for use in an oilfield tool. The valve includes a valve body and a valve member disposed in the valve body. The valve member is movable between an open and closed position. The valve member includes an aperture therethrough. The valve further includes a pressure relief member disposed in the aperture, whereby at a predetermined pressure the pressure relief member will permit fluid communication. In another aspect, the invention provides an apparatus and a method for introducing fluid into a tubular.

Abstract: A method and apparatus for use in the oil well industry for running in drilling/production liners and sub-sea casings down a borehole through drilling fluid on a drill pipe using a running tool with the benefits of surge pressure reduction are disclosed. In accordance with the present invention, a surge pressure reduction tool includes a diverter device having a housing with a set of flow holes formed therein and a sliding sleeve residing within the housing having a set of flow ports formed therein. By aligning the set of flow holes of the housing with the set of flow ports of the sleeve, the tool is set in a “surge pressure reduction” mode. By shifting, or axially indexing, the sleeve downward, the set of flow holes is blocked by the sleeve thus setting the tool in a “cementing” or “circulation” mode. This shifting or indexing is accomplished using an indexing mechanism.

Abstract: A hydraulic control system and associated methods provides selective control of operation of multiple well tool assemblies. In a described embodiment, a hydraulic control system includes a control module which has a member that is displaceable to multiple predetermined positions to thereby select from among multiple well tool assemblies for operation thereof. When the member is in a selected position, an actuator of a corresponding one of the well tool assemblies is placed in fluid communication with a flowpath connected to the control module. When the member is in another selected position, the flowpath is placed in fluid communication with an actuator of another one of the well tool assemblies.

Abstract: A valve with the following components: a pipe; an inner sub connected to the pipe; an outer sub connected to the pipe, wherein the inner and outer subs are concentric and define a sub annulus; a conduit between the sub annulus and an inside diameter of the inner sub; a sleeve slideably positioned within the pipe such that in at least one position the sleeve closes the conduit, wherein the sleeve comprises a section of relatively larger outside diameter and a section of relatively smaller outside diameter which define a pressure area on the sleeve between the diameters; and a lock of the sleeve in a position which closes the conduit.

Abstract: The present invention provides a method and an apparatus for use in a wellbore tool. The apparatus includes a body and a sliding member, wherein the sliding member and a mechanical portion moves between a first position and a second position. A valve assembly causes the sliding member and mechanical portion to shift to its second position at a predetermined flow rate of fluid through the body. The invention also provides an apparatus for a downhole tool that includes a mandrel and a sliding member disposed on the mandrel. The sliding member including a plurality of fingers and a plurality of heads, wherein the plurality of fingers are slideably recessed within a plurality of longitudinal grooves. The invention further provides a collet assembly that includes a body and at least two extendable members, whereby as the members extend outward, the members are rotated.

Abstract: The present invention provides a method and an apparatus for a dynamic mudcap drilling and well control assembly. In one embodiment, the apparatus comprises of a tubular body disposable in a well casing forming an outer annulus there between and an inner annulus formable between the body and a drill string disposed therein. The apparatus further includes a sealing member to seal the inner annulus at a location above a lower end of the tubular body and a pressure control member disposable in the inner annulus at a location above the lower end of the tubular body. In another embodiment, the assembly uses two rotating control heads, one at the top of the wellhead assembly in a conventional manner and a specially designed downhole unit. Thus, creating dual barriers preventing any potential leak of produced gases or liquid hydrocarbon on to the rig floor, thereby ensuring the safety of the rig operators.

Abstract: According to the present invention, the flow-activated valve assembly is a fluid-driven tool for use in various down hole drilling and fishing operations, which is activated by the introduction of fluid into an enclosed assembly, whereby fluid forces a movable portion of such assembly to slide until it engages a stationary portion, where an impact is realized, and at which time the fluid is permitted to exhaust. Upon this impact, another valve is opened to permit fluid to flow in another channel, moving the assembly in the opposite direction until it reaches a second stationary portion, at which point another impact is realized in the opposite direction. This creates a bi-directional hammering effect for each cycle of the tool, which can be utilized in various applications, either for the jarring effect, the linear motion, or a combination of both.

Abstract: An interventionless bi-directional barrier device of a downhole tool for use in a wellbore and a method of utilizing the barrier device to control the flow of production fluids in the wellbore are described herein. The barrier device includes a flapper mechanism having first and second flappers articulably linked together and articulably linked to a base member that is slidable within the downhole tool. The flapper mechanism provides a seal between opposing uphole- and downhole ends of the downhole tool upon actuation thereof. The method of controlling the flow of production fluids in the wellbore includes closing the barrier device to block flow through the tool, supporting the barrier device from a pressure exerted from a first direction, and supporting the barrier device from a pressure exerted from a second direction.

Abstract: A valve has a pair of surfaces, such as those of pipes, with an inflatable bladder disposed therebetween. Controlled inflation and deflation of the bladder provides for control of flow through the valve. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: An improved control system, particularly useful for SSVs, is disclosed. It is responsive to a rupture of the tubing and control line to equalize pressure on an operating piston to allow the SSV to go to its failsafe position. The annulus pressure-sensing feature can be employed with a variety of control systems, a particular one is used as an example.

Abstract: A seal is provided to prevent contamination by sand or grit in the clearance between a flow tube and the inner housing wall in a safety valve. An enlarged space is provided adjacent the seal to allow accumulation of sand or grit in the annular clearance space without causing seizure of the flow tube. The insert safety valve is assembled without a spacer with a seal mounted to the lower end of the insert valve to engage the bottom sub on the SSV. As a result, particularly for larger sizes of insert safety valves, the assembly is lighter and shorter, which facilitates use of readily available standard lubricator and wireline equipment.

Abstract: A method of isolating a reservoir of production fluid in a formation comprises providing a pair of valves (14, 16) in a bore intersecting a production formation and in which the hydrostatic pressuer in the bore at the formation is normally lower than the formation pressure, and then ontrolling the valves (14, 16) from surface such that the valves (14, 16) will only move from a closed configuration to an open configuration on experiencing a predetermined differential pressure across the valves.

Abstract: A device and method for selectively controlling the flow of production fluid through a tubing string in an oil and gas well according to which a housing is connected to a tubing string for insertion into the well, and well fluid is passed from the ground surface into the housing. The housing is provided with a plug to establish well fluid pressure in the housing to actuate a packer and/or other ancillary devices. The plug can be removed from the hosing by increasing the pressure of the well fluid in the housing above a predetermined value, thus permitting the flow of production fluid from the formation zone, through the housing and the tubing string, and to the ground surface.