Showing papers on "Annulus (oil well) published in 1981"

A theoretical model for core-annular flow of a very viscous oil core and a water annulus through a horizontal pipe

Abstract: Abstract A theoretical model has been developed for core-annular flow of a very viscous oil core and a water annulus through a horizontal pipe. Special attention was paid to understanding how the buoyancy force on the core, resulting from any density difference between the oil and water, is counterbalanced. This problem was simplified by assuming the oil viscosity to be so high that any flow inside the core may be neglected and hence that there is no variation of the profile of the oil-water interface with time. In the model the core is assumed to be solid and the interface to be a solid/liquid interface. By means of the hydrodynamic lubrication theory it has been shown that the ripples on the interface moving with respect to the pipe wall can generate pressure variations in the annular layer. These result in a force acting perpendicularly on the core, which can counterbalance the buoyancy effect. To check the validity of the model, oil-water core-annular flow experiments have been carried out in a 5.08 cm and an 20.32-cm pipeline. Pressure drops measured have been compared with those calculated with the aid of the model. The agreement is satisfactory.

Method and apparatus for controlling the flow of drilling fluid in a wellbore

Abstract: A method for controlling the flow of drilling fluid through a subaqueous wellbore is disclosed. The method comprises the steps of continuously measuring the output flow rate (A) of the drilling fluid from the wellbore, the input flow rate (B) of the drilling fluid to the wellbore, and at least a component of the pitch and roll (P/R) of the vessel, computating a floating alarm limit (C) dependent upon the pitch and roll (P/R) signal and the roughness of the sea, filtering the periodic fluctuation of the output flow rate (A) due to the motion of the vessel, and computating the delta flow signal (D) by subtracting the input flow rate (B) from the filtered output flow rate (A). The method further comprises the step of generating a signal whenever the absolute value of the delta flow rate (D) exceeds the floating alarm limit (C) to provide a visible warning that the flow of drilling fluid is out of control and to either close off the wellbore in case of a kick or to stop the flow of fluid and stop drilling in case of lost returns. Apparatus for controlling the flow of drilling fluid through a subaqueous wellbore is disclosed while drilling from a floating vessel. The wellbore is connected to the lower end of the drill string and the lower end of an annulus by a valve through which the drilling fluid flows. The upper end of the annulus is connected to a conduit from which the drilling flows to the suction side of a pump which circulates the drilling fluid therefrom into the upper end of the drill string, through the wellbore, and back up the annulus into the conduit. The apparation comprises an output flow meter connected to the exit of the conduit, an input flow meter connected between the pump and the upper end of the drill string, means mounted on the vessel for sensing the pitch and roll of the vessel, and computer means for receiving the output flow rate (A) signal from the output flow meter, the input flow rate (B) from the input flow meter, and the pitch and roll (P/R) signal from the pitch and roll sensing means. The computer means calculates an alarm limit (C) based on the pitch and roll (P/R) signal and the roughness of the sea continuously filters the periodic fluctuation of the output flow rate (A) due to the motion of the vessel, computes the delta flow signal (D) by subtracting the input flow rate (B) from the filtered output flow rate (A), and generates a signal whenever the delta flow rate (D) exceeds the floating alarm limit (C) to provide a warning of a possible blowout or lost circulation condition and to either close off the wellbore in case of a kick or to stop the flow of fluid and stop drilling in case of lost returns.

Concentric tubing having bonded insulation within the annulus

Abstract: An insulated concentric tubing well element having an inner tubing and an outer tubing with a substantially solid insulating material in the annulus between the inner and outer tubing A bonding material fills the voids in the annulus and the surface of the solid insulating material The bonding material prevents movement within the annulus and seals the annulus Calcium silicate is disclosed as a suitable material for the solid insulation and sodium silicate is disclosed as the bonding material A method is disclosed for producing the complete well element

Control pressure actuated downhole hanger apparatus

Abstract: A hanger and valve assembly which can be employed as a safety valve assembly to close both the production tubing and the tubing-casing annulus in a subterranean well is disclosed. The assembly includes a hydraulically activated, mechanically locked hanger which has slip anchoring members engaging the casing or, exterior conduit for preventing movement in both longitudinal directions. The hanger also has annular packing elements to seal the tubing-casing annulus. An annulus safety valve member employing a longitudinally recessed resilient seal member can be mounted in a landing nipple mounted in the hanger. By recessing the seal it is protected from the turbulent flow through the valve. A second shuttle located in the landing nipple is employed in conjunction with the first annulus safety valve to permit flow in one direction while metering flow in the opposite direction. This assembly is especially useful for permitting the injection of treating fluids through the annulus and production through the tubing or inner conduit. A conventional safety valve is employed to prevent flow though the tubing when control pressure is lost or reduced. Both the valves and the hanger can be activated by control fluid pressure through the same control line. A setting sleeve which can be mounted in the annulus safety valve landing nipple prior to installation of the annulus safety valve can be used to permit the hanger to be set using control fluid pressure.

High-pressure wellhead seal

Abstract: A tubing head, tubing head adapter and tubing hanger are sealed against annulus fluid or downhole pressure by an upper and a lower, pressure-energizing sealing assembly. The sealing assemblies are bi-directional, pressure-energizing and operate under working pressures of up to 30,000 psi. Each assembly consists of a metal seal ring made of highly elastic and ductile 316 stainless steel with a yield strength of approximately 30,000 psi, having a frustoconical shape, with the upper and lower tips of the cone enclosing an angle of approximately 28° in the prestressed state. In the axial direction, the seal ring engages a support ring on one end and a tubing hanger shoulder at the other end, both of which form inclines of 30° with the vertical (radial) plane. The support ring and the tubing hanger shoulders are made of materials having yield strengths of 50,000 psi and 75,000 psi, respectively. The preload applied to the seal assemblies is such that the seal ring plastically conforms to the harder surrounding surfaces and assumes a cone taper angle of 30°, in conformity with the mating support ring and tubing hanger shoulder. Thereafter, working pressure applied from either axial direction will be resolved along the incline of interacting surfaces into radial components which further enhance the sealing pressure along the inner and outer sealing surfaces. Because of this bidirectional pressure-enhancement, both seal assemblies may be tested through the application of test pressure from one common test port located between the two assemblies.

Downhold injection of well-treating chemical during production by gas lift

Abstract: A liquid well-treating chemical composition is injected into the production tubing during gas lift operations by providing a differential pressure operated valve downhole from the lowermost gas lift flow valve and maintaining sufficient liquid head of the chemical composition in the annulus to open the valve and cause the liquid chemical composition to pass into the interior of the production tubing.

Method for preventing annular fluid flow

Abstract: A method for preventing annular fluid flow following primary cementing of oil and gas well casings is disclosed. Pursuant to said method the casing is vibrated so as to maintain the hydrostatic pressure of the cement column surrounding the casing at or above the pressure of the fluids in the various formations penetrated by the well until the cement has acquired its initial set. The vibration may be either continuous or intermittent. Preferably, the vibration has a low frequency. The method may include the additional step of applying pressure to the surface of the cemented annulus while the cement is curing. The vibration may be induced in several ways. For example, the casing may be vibrated by simultaneous or sequential explosions of a slow-burning black powder. Alternatively, hydraulic jars may be used to strike blows on the casing causing the casing to vibrate.

Subsurface well apparatus

Abstract: There is disclosed a subsurface well completion system comprising body means having a bore therethrough adapted to be connected in axial alignment with a tubing string suspended within a well bore, and a packer carried by the body means for closing off the annulus above a production zone of the well. Flow through each of the bore of the body means and a passageway within the body means which bypasses the packer to connect the annulus above and below the packer is controlled by safety valves having pressure responsive operators for moving such valves from normally closed to open positions by means of control fluid which is supplied thereto through a control line from a remote source. Upon loss of control fluid, as, for example, due to loss of the control line, the valves automatically close. The pressure responsive operator for the tubing safety valve is carried within a tool which is landed within and retrieved from an upper pocket in the body means to one side of its bore, and the pressure responsive operator for the annulus safety valve, as well as a means for supplying control fluid to a means for releasing the packer to be set, are carried within additional tools which are landed within and retrieved from a lower pocket therein. The tubing safety valve is moved to open position and held in open position irrespective of control fluid by means of still another tool which is landed in the upper pocket, when the tool carrying pressure responsive means for operating the tubing safety valve is removed therefrom, so that the annulus safety valve tool may be substituted in the lower pocket for the packer releasing tool, after the packer is set, without risk of severing the wire line on which such tools are run.

Use of marker fluid in cementing offshore wells

Abstract: Cementing casing in an offshore well by displacing a drilling fluid with a settable cement slurry wherein there is injected into the annulus between the sidewall of the well and the casing ahead of the cement slurry a slug of a visually identifiable marker fluid containing cement, water, particulate carbon black, coal dust, and a surface active agent; visually observing when the fluid being displaced from the annulus changes from drilling fluid to marker fluid, and shutting in the well to allow the cement slurry to set.

Annulus safety apparatus

Abstract: A hanger and valve assembly which can be employed as a safety valve assembly to close both the production tubing and the tubing-casing annulus in a subterranean well is disclosed. The assembly includes a hydraulically activated, mechanically locked hanger which has slip anchoring members engaging the casing or, exterior conduit for preventing movement in both longitudinal directions. The hanger also has annular packing elements to seal the tubing-casing annulus. An annulus safety valve member employing a longitudinally recessed resilient seal member can be mounted in a landing nipple mounted in the hanger. By recessing the seal it is protected from the turbulent flow through the valve. A second shuttle located in the landing nipple is employed in conjunction with the first annulus safety valve to permit flow in one direction while metering flow in the opposite direction. This assembly is especially useful for permitting the injection of treating fluids through the annulus and production through the tubing or inner conduit. A conventional safety valve is employed to prevent flow through the tubing when control pressure is lost or reduced. Both the valves and the hanger can be activated by control fluid pressure through the same control line. A setting sleeve which can be mounted in the annulus safety valve landing nipple prior to installation of the annulus safety valve can be used to permit the hanger to be set using control fluid pressure.

Concentric steaming string downhole apparatus

Abstract: A downhole concentric tubing string is disclosed for use in distributing steam, or other hot fluids, to separated subsurface formations along a well bore. The apparatus includes elements for deflecting the steam from one string into the annulus of a cased well for injection through openings into the formation, elements for conducting the steam in another of the concentric string to a second set of openings for injection into another portion of the formation, and elements for isolating and separating the two separate injection intervals.

Device and method for fabricating multi-layer tubing using a freely suspended mandrel

Abstract: A device for fabricating multi-layer tubing has a reservoir for tubing solution and discharges such solution from an opening in the reservoir bottom. The reservoir is suspended so as to remain level. Extending through the opening is a vertical rod of smaller diameter but itself suspended by a flexible wire so as to remain vertical. Material in the reservoir extrudes as an annulus even in cross-section by passing between the edge of the reservoir opening and the rod. Such extruded material hardens into one layer of the tubing. There is a repetition with a larger reservoir opening and so depositing a larger tube that is dried on and over the first tube. This is repeated as often as desired to get a finished tube of the proper inside and outside diameter. The method is following in succession the steps described above.

Apparatus with annulus safety valve for through tubing injection and method of use

Abstract: An assembly including a tubing safety valve and annulus safety valve mounted within nipples incorporated within an inner conduit is disclosed for use in conjunction with the injection of material, such as gas, through the center of the inner conduit. The injected material can be used to stimulate production of fluids from the formation through the annulus between the inner conduit and an outer concentric conduit. This outer concentric conduit normally comprises an existing producting tubing string having existing safety valve nipple and external control fluid lines. Nipples incorporated within the inner conduit provide means for sealing the annulus between the inner and the outer conduit and for positioning the inner conduit relative to the outer conduit to provide communication between the tubing safety valve and the annulus safety valve and the external existing source of control fluid pressure. Bypass ports above and below on opposite sides of the annulus seals extend through the nipple members and an axially reciprocal annulus safety valve mandrel is moved from a position closing at least one of the bypass ports to an open position when subjected to control line pressure. Both the tubing safety valve and the annulus safety valve are activated when subjected to a common source of control line pressure.

In-situ combustion method for controlled thermal linking of wells

Abstract: A method of controlled thermal linking of an injection well and a production well, both penetrating an underground formation, accomplished by injecting oxidant into the annulus of the injection well and fuel into the tubing of an injection well in stoichiometric proportions, and initiating a combustion zone at the production well which propagates along a predictable path in the formation which is a deviated or horizontal portion of the injection well.

Method and apparatus for forming a heat exchange system in the earth

Abstract: A method and apparatus for forming a heat exchange system in the earth. A curve hole is formed in the earth having a substantially constant radius of curvature and is cased to form a cased flowpath therethrough. The apparatus used for forming the hole is comprised of a trailer having a frame on which a plurality of drill pipe supports are pivotably mounted. A curve drill pipe is supported by said supports and is connected at one end to a pressurized drilling fluid source. The pipe is fed into the earth and the fluid exiting from the leading end cuts a hole in advance of the pipe. When the pipe has been fed completely through the earth and the leading end breaks the surface, the fluid is stopped and a casing is connected through an adaptor to the leading end of the pipe. The pipe is then withdrawn through the hole to draw the casing through the hole. The annulus between the casing and the hole is filled with a particulate heat conductive material as the pipe is withdrawn.

Method for completion of wells

Abstract: A method of completing wells comprising: an inflatable packer used to plug the borehole below the producing formations; casing being run from the surface to a point above the producing formation; the casing annulus being sealed off above the producing formation; the producing formation being underreamed and gravel packed to improve productivity. Sealing of the casing annulus may be accomplished by conventional well cement or by a second inflatable packer. The inflatable packers used are inflated with fast hardening well cement which is retained in the packer annulus by means of a check valve so as to effect an immediate seal and anchor which is maintained during and after hardening of the cement.

Method of mixing fluids in a well bore

Abstract: A method of mixing fluids in a well bore employing a tubing string with a mixing valve disposed thereon. The well bore is sealed below the mixing valve, a first fluid then being pumped down the tubing string and a second fluid being pumped down the well bore annulus. By varying pressures and through the optional use of a circulating valve in conjunction with the mixing valve, the fluids may be mixed in the well bore or in the tubing string.

Casing bore receptacle with fluid check valve

Abstract: Apparatus for use in injecting treatment solutions through the annulus between two concentric conduits, such as tubing and casing, and then circulating it upwards with produced hydrocarbons. The apparatus comprises an integral valve and seal, including a mandrel, a packoff valve and a casing bore receptacle. The mandrel is incorporated in the tubing, and the casing bore receptacle is incorporated in the casing. The packoff member is releasably carriable on the mandrel and comprises an integral check valve and a radially expandable latch which is cammed outward by the relatively movable mandrel. The annular packoff member has seals on the interior and exterior surfaces for providing sealing integrity between the mandrel and the casing bore receptacle. The integral check valve permits fluids injected from above to flow radially across the packoff member between longitudinally annular flow paths defined by the packoff member and the casing, and by the packoff member and the mandrel. Net pressure in the annulus below the packoff member urges the check valve to the closed position.

O-Ring gaskets and method of manufacturing same

Abstract: A gasket including an O-ring (12) of an elastomeric material and an annulus (14) formed from a substantially continuous filamentary material, which is wound to form the annulus, the fibre being incorporated in a resinous material and the O-ring being attached to the inner periphery of the annulus.

Wash tool method for subterranean wells

Abstract: The disclosure relates to an improved tool and method for effecting the washing of sand or particulates from casing perforations and channels in production formations in subterranean wells. The tool employed comprises an outer body suspended from a first tubing string and having vertically spaced seals in engagement with the casing wall above and below the set of casing perforations to be washed. Radial wash ports are provided in the outer body between the annular seals. An inner body, carried by a second tubing string is inserted within the first tubing string and outer body and effects a sealing engagement with the bore of the outer body at a location below the radial wash ports. Washing fluid is then introduced into the well through the annulus defined between the first and second tubing strings and the sand laden washing fluid is returned to the well surface through the bore of the inner body and the connected second tubing string.

Chemical method and apparatus for perforating drill collars

Abstract: Discloses a method and apparatus to help provide fluid pressure in a well bore sufficient to overcome in situ earth formation pressures by perforating a circulation port through the sidewall of a drill collar above the drill bit to provide circulation of weighted drilling fluid down through the drill spring and back up the well annulus. Includes the lowering of a chemical reactant wireline perforating tool to a designated position within a drill collar, placing a single chemical flow jet into position addressing the sidewall of the drill collar, forcing the chemical reactant through the jet under high pressure and at high temperature to react with the drill collar metal and thereby remove a portion of the metal with the remaining metal defining a fluid circulation port through the drill collar wall, and pumping fluid through the port to establish circulation. Apparatus includes a tool body defining a single fluid flow jet, pressure actuated slips with the body to support the body against a vertical movement within the drill pipe, a body of chemical within the tool, a reaction section to heat the chemical, a pressure responsive decentralizing mechanism to position to the tool and thereby place the flow jet into position to direct the chemical directly onto the interior wall of the drill collar, and an electrically ignited propellant within the tool to set the slips, move the chemical through the reactant body, actuate the decentralizing mechanism, and force the chemical into reacting connection with the drill collar wall.

Apparatus for positioning a treating liquid at the bottom of a well

Abstract: This invention relates to a method and apparatus for positioning a selected liquid at the bottom of a well, such as an oil well, while having in the well at least a string of tubing, a sucker rod pump, a string of sucker rods, and a standing valve, without disturbing the rods, pump, tubing, or standing valve. A bypass conduit or shroud surrounds the wall of the tubing at a point above the pump where there is an opening in the wall of the tubing and is carried down, outside the tubing to a point below the conventional mud anchor, into the inlet of an overpressure relief valve. The outlet of the valve empties into the well annulus. If the normal pressure at the bottom of the tubing due to the head of liquid in the tubing is P, the overpressure valve is set to open at a pressure of P+P1, where P1 is a selected value, such as say 100 psi. At the surface, means are provided to close off the top of the tubing. Means are provided to inject the selected liquid into the top of the tubing at a selected pressure P2 above atmospheric, where P2 may be say 150 psi. This causes the pressure at the bottom of the tubing to rise to P+P2. Since P+P2 is now greater than P+P1, the overpressure valve will open and pass as much liquid as is pumped into the tubing at the surface. A crossflow unit is inserted into the tubing and the shroud at the standing valve to permit the radial flow of well fluids from outside the shroud to the inlet to the standing valve, and to permit the longitudinal flow of liquid down the annulus inside the shroud, to the relief valve.

Valving apparatus for selectively sealing an annulus defined between a work string and the bore of an element of a production string of a subterranean well

Abstract: The disclosure provides a valve for an annulus defined between a tubular work string or other conduit and a surrounding annular portion of an operative element disposed on production string, such as a safety valve. The annulus valve comprises an annular valve body, which may comprise an elastomeric mass, which is urged by resilient means into sealing engagement with the exterior of the tubular work string and is shiftable out of such sealing engagement, such as by an annular piston which is responsive to control fluid pressure. The same control fluid pressure may be utilized to operate the safety valve to its open position.

Fluid containment annulus for fixed angle rotors

Abstract: A centrifuge rotor for carrying a plurality of centrifuge tubes at a fixed angle with respect to the spin axis of the rotor wherein the rotor has a containment annulus located above the tube cavities in the rotor for containment of any excess fluid from the centrifuge tubes during centrifugation. The containment annulus is designed in such a manner that it will receive all possible excess fluids from the centrifuge tubes during centrifugation and none of the excess fluid will contact or exert pressure on the rotor lid.

Pipe Flow Rheometry: Rheological Analysis Of A Turbulent Flow System Used For Cement Placement

Abstract: Rheological characteristics of cement slurries and spacer fluids used in oil and gas reservoirs were evaluated using pipe-flow rheometry. Rheological analysis indicates that all cement and spacer fluids are best described by a power law model. The rheological properties of cement slurries are shown to be modified by wall slip which is attributed to particle migration away from the pipe wall when the fluid is sheared. Wall slip makes the attainment of turbulent flow in the pipe or annulus more difficult to achieve. A turbulent flow spacer fluid is designed that exhibits no wall slip and has excellent fluid-loss control. Field evaluation of this fluid supports the belief that turbulence in removing drilling fluid improves primary cementing. 20 refs.

Benchmark for use in arctic regions

Abstract: Method and apparatus for installing a benchmark in an arctic region to provide an accurate, reliable reference point even after prolonged periods of exposure. To install the benchmark, a hole is formed through the active layer and into the underlying layer. An alignment jig mounts a marker element in a casing and both are positioned into the hole. A leveling clamp on the casing is used to plump and adjust the marker element to a known elevation. The marker element extends to the bottom of the hole while the casing terminates at a depth which is above the bottom of the hole but below the bottom of the active layer. A settable material, e.g. sand-water slurry which will freeze at ambient conditions, is poured into the hole to a point just above the lower end of the casing and is allowed to set after which the remainder of the hole around the casing is filled. The annulus within the casing around the marker element is filled with fluidic material which will not freeze under ambient conditions, e.g. grease. Since the marker element does not directly contact any part of the active layer, the marker element is effectively isolated from contact therewith so that the thawing and refreezing of the active layer do not disturb the position or elevation of the benchmark. Temperature sensors, positioned along the marker element, provides temperature readings for which expansion coefficients are known which, in turn, are used to correct the actual elevational readings taken during a survey.

Permanent thermal packer

Abstract: A permanent thermal packer is disclosed for sealing the annulus between an injection tubing string and a well casing. The packer is thermal cement and is placed from within the injection tubing string to seal a substantial portion of the annulus above the injection zone. The packer provides a means for sealing the annulus above the injection zone thus permitting insulating material to be placed in the annulus above the packer with the expectation that it will not be damaged by well bore fluids.

Four-stroke oscillating piston IC engine - has cylindrical piston with ribs projecting into annulus forming working chambers

Abstract: The engine has a cylindrical piston with two radially projecting ribs (1). Each rib moves in a section of an annulus formed between the cylindrical part of the piston and an outer casing (5). The casing is closed axially by two end plates. It is divided by internally projecting sections which carry inlet and exhaust valves (9,10) facing into the annulus. These and the piston ribs divide the annulus into four working chambers which vary in volume as the piston oscillates. The piston is keyed to a shaft (6) which projects through an end plate and carries a connecting rod which is joined to a crankshaft.

Apparatus and method for controlling injection fluid flow in a well annulus

Abstract: A tubular member, to be a segment of the casing string, is provided with a polished bore at its upper end and a locking profile at its lower end. The locking profile includes a bearing shoulder and internal left hand threads for coaction with a latching mechanism. Another tubular member, to be a segment of the production tubing, has groups of circumferentially separated flutes to (1) maintain concentricity of the tubing segment, (2) provide axial flow passages between the segments, and (3) provide support for components of the tubing segment. A tubular packing mandrel, mounted on flutes, carries external annular packing for sealing engagement with the polished bore. The lower end of the packing mandrel defines an annular valve seat; and a tubular valve closure member, mounted in sliding, sealing relation on the tubing segment, has a coacting upward facing valve seat. A valve spring urges closure of the valve closure member. Lower flutes define a bearing shoulder for coaction with the casing shoulder to support the tubing string. A latching mechanism includes circumferentially separated axially extending spring fingers carrying external threads for coacting ratcheting and threaded engagement with the profile threads. When the tubing string is lowered to the support position provided by the bearing shoulders, the tubing segment is locked within the casing segment.

Bypass valve for sucker rod pumps

Abstract: A pipe section with an exteriorally secured valve body is arranged to be inserted in a lower portion of a well pipe string containing sucker rods and a lower pump, the pipe section and valve body being disposed slightly above the pump itself. A lateral pin passes through a connecting bore between the pipe section and valve body and is arranged to be urged in a lateral direction to operate the valve when the sucker rods are moved beyond their normal stroke within the pipe string. Opening of the valve serves to place the column of fluid in the well pipe string into communication with the well annulus and thereby permit emptying the pipe string of the fluid column and thus permitting the pipe to be pulled for repairing the pump or for other operations without the disadvantage of the heavy hydrostatic pressure resulting from the fluid column.