Abstract: A well completion system which includes a production packer assembly, production tubing sealed to the packer assembly, and an isolation assembly coupled with the packer assembly. The isolation assembly includes an isolation pipe received within a production screen and sealed at both ends therewith. The isolation pipe defines at least one port and carrying a moveable sleeve defining at least one aperture. The sleeve is moveable between an open position in which the port and aperture are in communication to permit fluid flow therethrough, and a closed position in which the port and aperture are not in communication and fluid flow is prevented. The isolation system is also coupled with a wash down shoe and a shearable ball seat.

Abstract: Preperforated tubing is produced by forming a perforation in flat strip of raw material, forming a hollow, cylindrical tube from the flat strip, and placing a removable plug into the perforation, so as to form a fluid-tight seal. A sealing element may be placed into the perforation. The perforation may comprise a hole, into which first and second countersinks may be formed. The sealing element may be placed into the first countersink, and the plug may be placed through the countersinks and the hole, such that the plug's body fills the hole and the plug's head fits within the second countersink.

Abstract: Cement plugs are positively placed in a wellbore by placement of a bridge plug immediately beneath the depth where the plug is intended and release of a seal allowing flow of cement slurry from a slurry containment tube as the tube is withdrawn to cause a positive piston-like displacement of the fluid in the wellbore.

Abstract: The perforations of a pre-perforated tubular are plugged with interior protruding, mostly hollow plugs which temporarily seal the perforations. The plugs are capable of withstanding a significant pressure differential and, when combined with an insert, forming a flotation cavity containing a buoyant fluid. The temporarily sealed tubular is then run into a wellbore, the tubular is set, and the plugs are unsealed. The unsealing is preferably accomplished by drilling out the interior protruding portions. Solid baffles may also be placed in the string to limit buoyant fluid loss in the event of premature unsealing in another embodiment of the invention.

Abstract: The flow apertures of a perforated mandrel are temporarily sealed by plugs which are made of a sacrificial material, for example, zinc, aluminum and magnesium. The sacrificial plugs prevent dirty completion fluid from passing through and in and out of the screen as it is run into the hole, thereby protecting the screen from plugging. During the time the screen mandrel is temporarily sealed by the sacrificial plugs, cleaning fluid is circulated through a work string and is returned through the annulus between the screen and the open well bore for removing filter cake, drilling debris and lost circulation material. After the annulus has been cleaned, the annulus is filled with an acid solution or caustic solution, which dissolves the sacrificial plugs. In an alternative embodiment, each sealing plug has a body portion and a stub portion which project into the mandrel bore. The sealing plug body portion is intersected by a vent pocket which is sealed by the stub portion.

Abstract: An air percussion hammer drill is disclosed for operation in an earthen formation. The air compression hammer mechanism comprises a piston that reciprocates while simultaneously rotating within its housing. A hammer drill bit slidably keyed to the bottom of the piston transfers the impact energy to the formation and rotates during operation independent of an attached drill string.

Abstract: The flow apertures of a perforated mandrel are temporarily sealed by a foil covering sheet which is made of a sacrificial material, for example, zinc, aluminum and magnesium The sacrificial covering sheet prevents dirty completion fluid from passing through and in and out of the screen as it is run into the hole, thereby protecting the screen from plugging. During the time the screen mandrel is temporarily sealed by the sacrificial foil covering, cleaning fluid is circulated through the work string and is returned through the annulus between the screen and the open well bore for removing filter cake, drilling debris and lost circulation material. After the annulus has been cleaned, the annulus is filled with an acid solution or caustic solution, which dissolves the sacrificial foil and opens the base pipe perforations.

Abstract: Sand control screens temporarily plugged with paraffin wax are installed in deep open hole wells wherein the wax has a melting temperature slightly greater or less than the nominal formation temperature in the zone from which well fluids are to be produced. Drilling fluids and other solids-laden wellbore fluids are removed from the wellbore by flowing the well up through a section of tubing disposed distal of the screen, through the interior of the screen and through the tubing string to the surface until the wellbore is cleaned. The wax is then melted due to the temperature of the produced fluid, is dissolved by the produced fluid or a solvent pumped down through the tubing string or is heated by a heater inserted into the interior of the screen such as a wireline conveyed electric heater. The distal tubing section is plugged so that production fluids are forced to flow through the sand control screen in a conventional manner.

Abstract: Under-balanced or potential fluid cross-flow conditions in a wellbore are minimized during installation of an auger-type gravel pack screen by placing a quantity of fine salt, calcium carbonate paste, a fluid loss control gel or sand within the interior space of the screen liner so that the material will form a substantially impermeable barrier on the liner, the gravel packing or the face of the formation during or after installation of the screen to minimize fluid flow in wells which have a relatively high pressure gradient. The material may be removed at will by circulation of a dissolving liquid such as fresh or unsaturated water or mechanical removal of insoluble material such as sand.

Abstract: This invention relates to a downhole activated centralizer for centralizing pipes in a wellbore for the exploration and production of hydrocarbons. The downhole activated centralizers are carried within either the pipe casing or the collars or both and remain generally within the maximum outward profile of the pipe string so as not to interfere with the movement and placement of the pipe string in the wellbore. The pipe string may be rotated, reciprocated and circulated which enhances the ability of the installer to place the pipe string in a deviated or long reach wellbore. Once the pipe string is in place, the centralizers may be deployed by one of several methods such that pistons mounted in openings in the peripheral wall of the pipe string move outwardly with sufficient force to move the pipe string way from the walls of the wellbore sufficient to form a complete annulus for cementing.

Abstract: A method of gravel packaging a well penetrating and in fluid communication with a subterranean formation or zone by sealing the apertures of a gravel pack liner, except near the bottom of the liner, against entry of slurry fluid. This prevents gravel from clogging the apertures or bridging the annulus between the liner and the well bore. An immobile gel provides the sealing function, and a breaker eventually breaks the gel, thereby permitting removal of the gel and unblocking the apertures. The gel is formed from a suitable liquid composition containing the gel breaker, and may be applied to the liner prior to lowering the liner and wash pipe into the well bore.

Abstract: A gravel packing process employs a staged screen assembly to prevent sand and other fine particles entrained in the produced hydrocarbon fluids from entering the production tubing and related equipment. The staged screen assembly is provided with a base pipe having rupture disks in its sidewall. The disks rupture at a predetermined pressure differential during gravel packing to enable leakoff of the carrier fluid from the gravel slurry into the base pipe and recirculation of the carrier fluid back to the wellhead, while ensuring complete and uniform gravel packing of the hydrocarbon production interval without substantial bridging or duning.

Abstract: A well drilled with air or gas as a circulating medium traversing pay zones with greater than normal pressures or pressures such that hydrocarbons would permeate drilling fluids and cement is drilled and completed while permitting a continuous flow of hydrocarbons from the well until it is desired to shut the well in at the surface. The intermediate casing string and the production casing string cooperate with the tubing so that the cement for the production string may be positioned without contact with the hydrocarbons.

Abstract: A method and system for selecting and arming each of a plurality of firing modules in a single-line selective perforating system is disclosed. A single firing line connects each firing module one at a time in a sequence to a control unit to receive power and control signals therefrom. Each module generates internally a module active time interval in response to being connected to the firing line power. Each time interval has a first portion during which the module generates an identification pulse to the control unit to uniquely identify that a particular module has been connected to the firing line, and a second portion during which the module is enabled to receive a selection pulse from the control unit to terminate further sequencing of the modules to locate the module to be selected. The next module to receive power from the control unit is connected to the firing line by a pass-through switch in the last connected module at the end of its active time interval if that module was not selected.

Abstract: A tubing string extends downhole in a cased borehole to a jet perforating gun. A packer device is located uphole of a releasable coupling apparatus. The coupling apparatus has an annular piston therein which is moved to release the lower string. Two spaced apart movable annular pistons are series connected in the tubing string at a location below the packer and above the gun. Flow ports, formed in the tubing wall, are covered by the pistons. A ball of appropriate diameter can be circulated downhole and seated upon either of the pistons, thereby forcing a selected piston in a downhole direction. Circulation ports are provided below the lower piston in proximity of a gun firing head. The lower piston includes a shaft depending axially therefrom and into proximity of a detonator of the gun firing head, so that when the lower piston is forced downhole, the shaft contacts the firing head which detonates the shaped charges of the perforating gun.

Abstract: Cement compositions which upon curing have high compressive strengths and are rapidly dissolved in acids are provided comprised of water, a metal halide or sulfate selected from the group consisting of magnesium, aluminum and zinc halides and sulfates, a metal oxide selected from the group consisting of magnesium, aluminum and zinc oxides and a metal carbonate selected from the group consisting of calcium and barium carbonates. Methods of using the cement compositions are also provided.

Abstract: A well liner for a subterranean well is provided comprising an elongated tubular member which may be a wire wrapped screen having a plurality of slots or passages which are disposed longitudinally and circumferentially of and extending from the outer surface to the inner surface of the tubular member, and an impermeable inorganic matrix substantially filling said slots or passages and coated upon said inner and outer surfaces, said matrix being the reaction product of a first reactant consisting essentially of magnesium oxide and a second reactant consisting essentially of magnesium chloride, in a solvent or solution therefor.

Abstract: A well liner for a subterranean well is provided comprising an elongated tubular member which may be a wire wrapped screen having a plurality of slots or passages which are disposed longitudinally and circumferentially of and extending from the outer surface to the inner surface of the tubular member, and an impermeable inorganic matrix substantially filling said slots or passages and coated upon said inner and outer surfaces, said matrix being the reaction product of a first reactant consisting essentialy of magnesium oxide and a second reactant consisting essentially of magnesium chloride, in a solvent or solution therefor.

Abstract: A perforated liner is sealed at longitudinally spaced intervals with a removable sealant. The partially sealed liner maintains sufficiently high fluid flow velocity outside the liner during gravel packing so as to prevent the formation of gravel dunes. After packing is completed, the sealant is removed permitting the passage of fluids through the liner.

Abstract: The perforations of a tubular pipe are sealed with a selectively removable plugging material. The pipe is then wire wrapped to form a well screen. The annular passage defined by the pipe and wire wrapping is restricted enough so that the flow resistance in the annular passage is sufficient to maintain high fluid flow velocity outside the well screen during gravel packing so as to prevent the formation of gravel dunes. After gravel packing is completed, the plugging material is removed, permitting the passage of fluids through the well screen and pipe mandrel.