Oil Well Plug Apparatus and Method

Abstract

An oil well plug apparatus and method for sealing oil and gas well casings has a plug assembly with an elongate plug body. A spinning knurled bit is attached by a shaft and bearing assembly to a first tapered end of the plug body. A seal disposed on the opposing second end of the plug body fills the clearance between the plug body and a well casing when the plug body is lowered into the casing. The plug assembly includes an anchor to which a chain and cable are attached for suspending and lowering the plug assembly into the casing of a blown out well. The chain reinforces concrete back-fill and a concrete mound capping the well. The cable is severed to release the tethered control of the plug assembly from above.

Description

FIELD OF THE INVENTION

The present invention relates to a plug apparatus and method for sealing oil and gas well casings. The apparatus is particularly useful in plugging damaged and out of control deepwater wells exhuming gases under high pressures through the well casing.

BACKGROUND

Using concrete and heavy mud to seal an oil or gas well is known in the oil and gas industry. However, in the worst off-shore oil spill in United States history that began Apr. 20, 2010, the conventional methods for sealing an out of control well under extremely high pressure proved to be ineffective. As a result, the BP Deepwater Horizon oil well explosion resulted in a disaster in which oil gushed from the out-of-control well for five months because of the difficulties in sealing the well in a deep underwater environment with oil and gas escaping under such high pressure. Eleven workers were killed and 200 million gallons of crude oil spilled into the waters of the Gulf of Mexico causing devastating environmental and economic damage.

BP's struggle with the disaster clearly illustrated the need for a readily available device to plug and seal a leaking high pressure well. In recent years and in the future, major oil companies are drilling deeper and larger diameter off-shore oil wells. Twenty-two inch to thirty inch diameter deep water oil wells have become the norm. For example, the BP Deepwater Horizon well included a steel casing of 22″ in diameter. Larger oil-well diameters produce more volume and more profit. However, large oil-well diameters produce large volumes of natural gases, combined with high internal well pressure.

As our worldwide oil reserves become more difficult and more expensive to extract, the oil wells needed to extract these reserves will become deeper and the oil well pipe casings will become larger in diameter. These oil wells include off-shore deepwater wells. As a result of this natural progression and the resulting sub-terrain and geological oil and gas pressures up to 5000 PSI, blow-outs will remain very difficult to control within the confines of off-shore cased oil wells. These well casings are vertical tunnels to reserves that are subject to damage and pose future problems. In particular, large sized wells exist at great depths into the ocean floor, which leads to elevated up-blast pressure emitted by gas pressure that make these wells difficult to plug and seal. This creates a problem for the oil companies because of the potential environmental damage to our oceans. Therefore, precautions in the way of methods and tools are needed to respond quickly in situations that a blowout preventer is damaged or a casing is damaged causing oil and gas under extreme pressure to spill.

Thus, there is a need for an available and workable oil-well plug for jumbo-size off-shore deepwater oil wells that are damaged and out-of-control.

Normally, concrete plugs are used to seal a normally function well. U.S. Pat. No. 4,840,346 to Adnyana and Rogen discloses an apparatus for sealing a well blowout and details using a plugging fluid such as cement, a heavy drilling mud or the like that can be pumped into the formation to kill the well. However, as can be seen from the recent BP disaster, heavy mud and cement can be insufficient to overcome the extreme pressures associated with a deepwater well. Additional consideration is needed to overcoming these extreme pressures along with the use of cement or heavy mud as a sealant.

It is well known that even in normally operating wells improvements are needed over the use of only cement or concrete. It is difficult to seal a well using concrete located in the casing because the casing is fairly smooth and does not provide much anchoring for the concrete plug. Further, concrete shrinks during curing, meaning that cracks, pores and thin annuli between the concrete plug and surrounding walls of the well may be formed. Further the long-time resistance of concrete to high pressure, high temperature and various chemical substances is uncertain, and thus the use of concrete plugs alone is linked to a future risk for leakage. Another problem related to concrete plugs in offshore wells is that the sea floor in some areas sinks due to the exploitation of hydrocarbons. This subsidence causes motion in the ground, which causes stresses in the concrete plugs, which again contributes to the cracking of the concrete. The subsidence of the sea floor also increases the pressure of the reservoir. These effects contribute to the risk for leakage through the concrete plugs, which of course is highly undesirable.

All of these problems with using only concrete to plug an oil well are exacerbated when the well is damaged or out of control. The high up-blast pressure present in a casing after damage to the well can make it difficult to install sufficient concrete and to permit the concrete to cure.

Other attempts have been made to improve the options for plugging an off-shore well casing. For example, FR2663678 to Dowell Schlumberger uses a plug having a core with an elastomeric lining that is deformable. The plug does not have a means for guiding to the plug into the casing and the profile and the elastomeric lining creates friction and other difficulties that would make insertion difficult. While the plug used by Schlumberger is uses in improving a concrete plug, the improved plug does not address the need for insertion of a plug into a gushing well with a highly pressurized casing.

In another example, U.S. Pat. No. 6,478,088, Hansen and Solversen use a liquid curable resin to form a plug in the well. Again, the technology provided does not offer a way to overcome the extreme pressure posed by a damaged well. While Hansen and Solversen provide a mechanical device for insertion in a casing, the pressure in a damaged well would prevent the easy insertion of the mechanical packer and subsequent formation of a resin plug. Thus, the device is impractical for using as taught to seal a gushing well.

The object of the present invention is to provide an apparatus and method for plugging the petroleum well that is damaged in which the above problems are reduced or eliminated. These and other objects and variations will be evident to those skilled in the art based on the invention defined by the claims below and described in the summary and detailed description that follows.

SUMMARY OF THE INVENTION

The present invention addresses the need for an effective means to plug and seal an oil well having a shaft of any size, especially jumbo sized, and at any depth under the sea. The invention provides an apparatus and method to plug and seal out of control damaged off-shore deepwater oil and gas wells by finding and penetrating the powerful up-blast oil and gas pressures of large steel cased off-shore deepwater oil wells.

A plug assembly is provided having a computed penetration weight. The plug assembly is combined with a GPS, laser, or magnetic guidance system to guide the plug to the mouth of a casing. The plug assembly has a plug body with a streamline profile design and is tipped with a nosecone spiral spinner bit. With the combination of the body design and bit and a low friction coating on the plug's body, the plug assembly will penetrate the oil and gas up-blast pressures exiting the casing. The energy, weight and directed and concentrated force of the plug apparatus overpower the forces from the gushing well and provide a step to plugging the oil well. The weight and guidance of the plug assembly can be adjusted for insertion into a casing regardless of the depth of the well, the casing size or the blow-off pressures.

Once the plug assembly is inserted into the casing, the plug body is sealed within the casing by concrete, which is reinforced by a chain attached to the plug body. A quantity of concrete is mounded above the casing for additional support to ensure the quality of the seal. This mound is further reinforced by the outward flange of the casing and the chain. Once, the concrete is set, a cable attached to the chain that was used to lower the plug assembly to the casing may be severed for permanently sealing the well.

An object of the present invention is to provide a plug apparatus for out of control and gushing deepwater oil wells that can be fabricated to the specifications of a particular well and kept in stock ready for use by major oil companies and drilling contractors.

Another object of the invention is to provide a plug apparatus that is easily transported on land or sea and used to plug and seal a well.

One object is to provide a plug apparatus that can be used from any off-shore oil well drilling platform, from deck of ship, or from an on-shore station using video monitoring.

Yet another object is to provide a plug apparatus that can be used in combination with a terrestrial crane for oil and gas well leaks that are difficult to control, or with a long-boom crane for use with burning wells and to extinguish oil well fires.

A particular object of the invention is to provide a method for the insertion and reinforcement of a plug that can be carried out with an out of control well under extreme pressures. A further object is to provide an assembly and a plug which are useful in the method. These objects are achieved by a method for the guided insertion and concrete reinforcement of a plug in a petroleum-well including a streamlined plug structure and nose bit for penetrating up pressure and guiding the plug into a casing.

Thus the invention relates to a both a method and a device for the insertion and reinforcement of a plug in a petroleum-well extending from the earth's surface or the sea floor to a petroleum reservoir, which said well includes a tubular pipe casing. According to the invention at least one opening is formed in the casing at a distance from the earth's surface. Then a solid plug with customized and penetrating design is provided for insertion into the opening of the casing, whereby the plug forms a seal of the well that is reinforced by concrete both within the casing and above the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a plug device for sealing wells in accordance with an embodiment of the invention.

FIG. 2A is a side view of a tip portion of the plug device in accordance with FIG. 1.

FIG. 2B is a cross-section of the tip portion shown in FIG. 2A.

FIG. 3 is a side view of an end of the device having a chain and cable attached.

FIG. 4A is a side view with partial cross-section of a blowout preventer portion of the device.

FIG. 4B is a side view of the plug device being inserted into a well pipe with the sea floor.

FIG. 5A is a cross-section view detailing the insertion of a seal of the device into a well pipe.

FIG. 5B is a cross-section view detailing the engagement of a seal of the device with the well pipe of FIG. 5A.

FIG. 6A is a cross-section view of a portion of the device detailing the insertion of the device with seals into the well pipe.

FIG. 6B is a cross-section view of a portion of the device detailing the seals of the device engaged with the well pipe.

FIG. 7A is a cross-section view of a well pipe and representation of the plug device inserted into the pipe prior to covering the pipe.

FIG. 7B is a cross-section view of a well pipe and representation of the plug device inserted into the pipe after covering the pipe with concrete.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the illustrations, FIG. 1 shows a plug assembly 10 in accordance with an embodiment of the invention. The plug assembly is used in the methods provided by the invention for plugging an oil or gas well. The plug assembly 10 includes a plug body 16 that is engineered with a preferred weight, length, and material desired for the method for inserting the plug assembly into a well casing exhibiting high up-blast pressure. The plug assembly 10 is particularly suitable for a deepwater oil and gas well in which sub-terrain geological circumstances present a high-pressure environment for the release of oil and gas in the case of an accident or disaster damaging the well or causing a leak.

The plug body 16 is constructed of a heavy high strength material used in creating the penetrating weight of the plug assembly 10. A preferred material for the plug body 16 is high strength solid steel in which the weight of the steel is calculated for conditions and pressure of the well. Solid steel will provide a mass of 490 pounds/cu ft for the plug body 16. The outer diameter of plug body 16 is predetermined by the well's casing 28. In particularly, the outer diameter of the plug body 16 will vary and be dependent on the diameter of the well's casing 28, usually also constructed of steel. The outer diameter of the plug body 16 is slightly reduced from the inner diameter of well's casing 28 to provide a clearance of about ¼″ to ½″ from the interior surface of the casing. The clearance between the plug body 16 and casing 28 eliminates any resistance of the casing to the insertion of the plug assembly 10 that could be caused by failure of the plug body to fit into the casing pipe. The clearance also reduces friction between the plug body 16 and interior casing surfaces during insertion of the plug assembly 10.

The length of plug body 16 is calculated and determined based on the needed dead weight to resist gas/oil pressure generated within the casing 28. The plug body 16 is constructed accordingly. The length of the plug body 16 may also be based on the particular well's casing length and size and whether the well is located in deep water, on land, or is a natural gas well. Once the design, weight and length of the plug body 16 is determined, the plug body may be fabricated and carried in stock for future emergency use by oil companies and gas producers according to each well's casing diameter and conditions.

Besides the length and weight of the plug body, the plug body 16 includes additional features to improve the device for plugging high pressure wells. For insertion through deep water, the plug body 16 is elongate, cylindrical and includes a first end with a gradually tapered nose. The design provides a streamlined plug body 16 that moves easily through water. In one application of the tapered nose on the first end of the plug body 16, the plug body includes a first narrowing 22 of the plug body and a second narrowing 26 of the plug body that provide for the gradual taper of the nose.

A pointed nose cone portion on the first end of the plug body 16 further streamlines the plug assembly to compliment the streamlined profile of the plug body. The pointed nose cone portion may comprise a bit 30 attached to the first end of plug body 16. These design features promote penetration of water currents by the plug assembly 10 and assist the plug assembly in moving along a straight line toward its target for insertion in to the mouth of an oil or gas well casing 28. Further, the combined weight and design promote the penetration of the plug assembly 10 through the pressures of gas and oil within the casing 28.

The plug body 16 is treated, coated or skinned with material to reduce drag caused by friction. In one embodiment, the surface of the plug body 16 is coated with a glazed epoxy coating system to create a friction reducing coating 18 with a high gloss finish. In particular multiple coats, at least three or more preferred, of epoxy developed for heavy duty service on metal substrates may be applied to the surface of the plug body 16 to create the friction reducing coating 18. Alternatively, a heat-cured powder coating could be used for the coating 18 or other low friction coefficient adherent coating such as ultra-hard carbon film or diamond. Regardless, the coating 18 should specifically provide a low friction skin on the plug body and will preferably cover the entire plug body 16 and possibly even the nose cone portion of the plug assembly 10. The low friction coating 18 assists in guiding the plug assembly through deepwater to the mouth of the casing 28 of problem oil well. With the low friction plug body 16 combined with the streamlined water dynamics of plug assembly 10 and guidance system 20, the plug assembly more easily remains under control until reaching the target casing. Further, the low friction coating 18 promotes and assists in the insertion of the plug assembly 10 into the casing 28.

Once the plug body 16 is completely inserted into the casing 28, a need is recognized to temporarily seal the plug assembly 10 therein to assist in back-filling. In the embodiments of FIGS. 5A-5B and 6A-6B, one or more seals 15a-15c and 15a′-15c′ are located about the circumference of plug body 16 to seal the plug body between the plug body and casing 28. In particular, seals 15a-15c are situated near a second end of the plug body 16 so as to allow the plug assembly 10 to near complete insertion into the casing 28 before attempting to seal the plug body therein.

These seals 15a-15c comprise flexible and compressible material so that the seals bend and compress to accommodate complete insertion of the plug body 16 into the casing 28 while lowering the plug assembly into the casing. Thereby, insertion of the portion of the plug body having the seals does not create a bottleneck in the process. An example is shown in FIG. 5B in which the seal 15a′ is a rubberized ring around the circumference of the plug body that compresses the seal while contacting the inner wall of the casing as the plug body gradually slides down into the casing as shown in FIG. 6A. In this case the rubberized seal is attached to the plug body by inserting the seal 15a into a channel as shown in FIG. 5A within the circumference of the plug body. Adhesive 17 is used to permanently affix the seals 15a-15c into the channel. In the exemplary embodiment, the seals 15a-15c are provided in triplicate to improve the resistance of the seal to pressure within the casing after the plug assembly is inserted. The triplicate seals 15a′-15c′ will each bear against the inner wall of the casing 28 when compressed as shown in FIG. 6B. These seals 15a-15c are spaced apart toward the second end of the plug body to provide separate points of sealing the plug body and promote the seals withstanding increased up-blast pressure within the casing. The seals are gradually engaged to the inner wall of the casing one at a time as shown in FIG. 6A until each of the seals are inserted. The seals 15a′-15c′ shown in FIG. 6B fill the clearance space between the plug body 16 and the inner wall of the casing 28.

The clearance of the plug body may be adjusted according to the preferred means of sealing the casing. For example if design or damage to the casing causes the casing to narrow from the mouth, then the plug body may be design to seal using a wedge shape and a series of increasingly large diameter seals. Further, as the narrowing will permit complete insertion of the plug body to a calculated depth, the seals may not be required to have flexibility and compression, but rather be rigid. In fact, some escape of up-blast pressure may be preferred to stabilize the well during the back-filling and capping process that follows insertion of the plug assembly.

The plug assembly 10 includes a guidance system 20 for controlling the location of the device as the device is lowered to the mouth of the well's casing 28. In one embodiment of the plug assembly 10, the guidance system 20 is integrated or attached at the nose cone portion of the plug body 16 or just above the attachment of the bit 30. Such guidance system may be attached by a threaded coupler for connecting the guidance system to the plug body 16 near or on the nose cone portion or bit 30. By locating the guidance system 20 near the nose cone portion of the plug body 16, the plug assembly 10 can be accurately guided to insert the nose cone portion of the plug body into the mouth of the casing 28. The guidance system 20 is remotely controlled from land, ship or platform and engineered using the most recent or preferred guidance technology. Options for the guidance system 20 include electric global positioning satellite (GPS), laser, or a magnetic guidance sensor. Those skilled in the art will recognize that these and other guidance systems may be modified and used in connection with the present plug assembly 10. As the technology of these guidance systems improves, such guidance technology should be incorporated for accurate insertion of the plug assembly 10 into a deepwater well.

A bit 30 is attached to the plug body 16 for driving the plug assembly 10 through water and high pressure environments. The bit 30 shown in FIG. 2A is made of steel or high strength aluminum and includes a base with a narrow tip on the base on the bit and a top portion with a broad shoulder on the top of the bit where the bit connects to the plug body 16 for spinning rotation. In particular, the bit 30 connects to the plug body 16 via the fitting end 32 of a steel shaft 40 and bearing coupling 38 as shown in FIG. 2B whereby the bit spins about the shaft while situated on the first end of plug body 16. Thus, the bit's narrow tip is shaped to provide a spinning nose cone point on the plug assembly 10 and cuts through water and pressure.

In one embodiment the bit 30 as shown in FIG. 2A, the bit comprises a spinner bit 34 that includes knurled blades 36 that are constructed of the same steel or high strength aluminum. Said blades 36 on the bit extend upward from narrow tip on base of the bit to the broad shoulder on the top of bit, and the knurled blades are curved to aid the spinning of blade and penetration of blade through water and pressure.

The plug assembly 10 includes a suspension system for hoisting and lowering the plug assembly to the mouth of an oil or gas well casing 28. In the one embodiment shown in FIG. 3 the suspension system includes a cable 11 that is attached from an oil platform, ship or crane boom. The cable 11 is attached to a chain 12, which is then attached to an anchor 14 that is affixed to a second end of the plug body 16.

In the preferred method for the invention, the chain 12 is constructed of high strength solid steel so as to provide sufficient strength for reinforcement of concrete. The chain 12 is attached to the anchor 14 by suitable means such as a closed hook attached to a loop on the anchor. For many deepwater wells, the chain may be constructed in desirable 8 inch length and 3 inch wide links, which provide excellent strength and size for reinforcement of concrete in large underwater casings. The overall desired length of the chain 12 will vary according to the specific well and casing application. The length of the chain 12 should not be so long as to leave a large portion of chain exposed on the ocean floor after being released. Rather, the length of the chain 12 may be adjusted in accord with the depth that the plug assembly 10 will be inserted into the casing 28, and in accord with both the height of the casing pipe extending above the ocean floor and the size of the mound 44 needed to seal the casing 28 in accordance with pressures in the casing. Moreover, the chain 12 should be sufficient size and length to reinforce the concrete within the mouth of the casing 28 and to reinforce the concrete forming the mound on top of the casing.

The cable 11 for attachment to the chain 12 and lowering the plug assembly 10 is comprised of a high strength material. Steel cable of two inches diameter will be suitable for envisioned oil and gas wells, but such may be adjusted according to technical needs to ensure the mission is accomplished expediently. The two inch diameter cable 11 is sized to suit the load of the typical plug assembly 10 that will provide the penetrating weight and force needed for insertion into a pressurized casing 28. The cable 11 may be secured to the chain 12 by suitable means. In one means as shown in FIG. 3, the cable 11 is run through a link of the chain 12 and then a portion of the tail of the cable is positioned next to a portion of cable of a length of about 24 inches. The cable's tail is welded to the other overlapping portion of cable to create a permanent attachment of the cable 11 to the chain 12 until the cable is severed.

In practicing one application of the method using the plug assembly 10, the plug assembly is deployed off-shore where the source of the oil leak is located at the mouth of a gushing well casing 28. The procedure presented may be assisted and coordinated with existing remote deepwater robot equipment or other equipment useful for positioning or other operations needed. Such equipment may be provided by companies or subcontractors involved with the particular well. Further, the procedures may be coordinated from available locations including off-shore platforms, ships, or on-shore facilities with remote video available.

In this example of the method, the oil well plug assembly 10 is obtained along with the sealer material comprising concrete, cement, or resin. Other support equipment such as robotics is retained as well, and the plug assembly 10 is moved to the location of a defunct and leaking oil well. While obtaining equipment or readying the plug assembly 10, the casing 28 is prepared for receipt of the plug. In particular, any dysfunctional blow-out preventer 50 is removed from the casing 28 and the oil well casing is cut below the blowout preventer with a robotic saw or other cutting device. The damaged blow out preventer shown in FIG. 4A is lifted and removed from the mouth of the well casing below so as to remove obstacles that might inhibit insertion of the present plug assembly 10 into the casing 28, which was once located below the blow out preventer 50. Any other obstacles blocking the mouth of the oil well casing 28 are also removed to expose the open mouth of the casing. As the casing 28 is prepared, the plug assembly 10, which is suspended and attached to the cable 11 from a platform or ship above in off-shore applications, is prepared for lowering to the mouth of the casing.

The plug assembly 10 is lowered to the mouth of the casing 28 as shown in FIG. 4B using guidance system to accurately position the nose of the plug assembly into the casing. A computer operated guidance program may be used in communication with the guidance system 20 on the nose cone portion of the plug body. The plug body 16 is lowered into the casing 28 according to the predetermined depth calculation. In particular, the depth for the plug is computed to determine the depth required to seal the well based on conditions of the casing, pressure conditions, and other variable requiring consideration such as the construction of the casing. As the suspended plug assembly 10 is lowered, the plug body is guided into the mouth of the casing 28 by lowering using the cable tethered to the platform or ship above. The combination of features of the plug assembly discussed above provides the energy, weight, and forces needed to overpower water and casing pressures. These features include the computed weight of the plug body 16, the energy of the bit 34, the nose cone design, streamlined profile of the plug assembly 10, and the reduced friction coating 18 on the plug body. Thus, the remote guidance system lowers the plug to the precise position desired in the well casing in accordance with the depth within the oil well casing calculated to satisfy the conditions calculated beforehand.

As the plug assembly 10 lowers to the well casing, the spinner bit 34 mounted on the plug body 16 will spin in accordance with water pressure applied to the plug to help drive the plug assembly straight toward the target. The plug assembly 10 penetrates water and pressurized gas and oil as the device is lowered promoted by the nose cone portion of the plug body 16, streamlined shape of the plug body, and reduced friction coating 18 on the plug body. As discussed, each element improves directional control and penetration of the plug assembly 10.

As the plug body 16 enters the casing, the plug body at least partially seals the casing using several seals 15a-15c that are provided in this example of the method. These seals, shown in FIGS. 5A-5B and 6A-6B, provide a temporary restraint of oil and gas gushing from the casing. Such restraint may assist in backfill of the casing with pressurized concrete or sealant material. The seals 15a′-15c′ abut against the inner wall of the casing as the plug body 16 is lowered into the casing.

After the plug assembly 10 is situated in the casing and before the tethered cable is disconnected, the oil well casing is back-filled with pump-mix concrete, cement or resin material as shown in FIG. 7A. Using 5000 PSI pump-mix concrete 42 is one preferred option that will work to permanently seal the leaking oil or gas well. This is a cold-water mix of concrete or cement that is pumped and piped via a pipe to the well casing at high pressure to displace water and gasses and back-fill the casing. The sealant material is fast-setting to prevent deterioration of the back-fill integrity by pressures on the well before the material can cure and set.

After the casing is back-filled, further concrete or other sealant material is poured on top of the well to form a protective cap to ensure the permanent integrity of the back-fill within the casing. As one option, the cap may be formed using 5000 PSI pump-mix concrete to form a pyramid mass of concrete into a large and heavy mound 44 over the casing 28 as shown in FIG. 7B. The mound 44 provides a final sealant and seals the residual pressures existing about the casing. The weight of the mound reinforces the seal of the mound and also the underlying seal of the back-fill within the upper casing, which is also reinforced by the high strength steel chain section.

Once the mound 44 is formed over the casing 28 and has had sufficient time to cure and set as desired, the cable 11 may be released from the chain 12. Forty-eight hours or more may be needed before the concrete or sealant material is sufficient hard, strong and cured for release of the cable. After the cable is released, the chain remains permanently as a steel reinforcement in combination with the outer flange of the steel cased oil well. This reinforces the concrete back fill 42 and mound 44 or other sealant material. The process of placing the steel plug body into the casing included tethering to a platform or ship above the oil or gas well. Now, the cable 11 may be released by cutting the cable near to the location of the chain 12 using a robotic saw, torch cutter, etc. Alternatively, the cable 11 may be released by dropping the cable from the platform or ship. Such cable 11 may be scheduled for later retrieval or disposal or left as debris for beneficial underwater habitat creation depending on the circumstances and environmental needs.

In practicing another application of the method of using the plug assembly 10, the plug assembly is deployed on-shore with an oil or natural gas well. The plug is deployed using hoisting equipment such as an all-terrain hydraulic crane, whereby the plug assembly is hoisted and suspended from the boom of the crane. The crane lowers the plug assembly into the mouth of well casing and because of the features of the plug assembly discussed. The plug penetrates the well casing even in environments where the oil or gas is gushing or out of control in the presence of up-blast pressures.

In practicing another application of the method of using the plug assembly 10, the plug assembly is deployed to a burning oil or natural gas well. In this case, long boom crane is used to hoist and suspend the plug assembly. The plug assembly is lowered into the mouth of the casing for the burning well from a position high above the flames. The plug eliminates the source of fuel for the fire by stopping the flow or oil or gas from the well.

Claims

1. An plug assembly for plugging the casing of a well comprising:

an elongate plug body having a first end and an opposite second end with an intermediate elongate portion between the opposing first and second ends;

a bit attached to a first end of the plug body, said bit including a top portion with a broad shoulder adjacent to where the bit is attached to the plug body and including a base with a narrow tip extending away from the plug body;

a seal on the plug body disposed toward the second end of the plug body; and

an anchor attached to the second end of the plug body for suspending and lowering the plug assembly.

2. A plug assembly for plugging the casing of a well as in claim 1 in which said plug body includes a friction reducing coating.

3. A plug assembly for plugging the casing of a well as in claim 2 in which said friction reducing coating comprises at least three layers of epoxy.

4. A plug assembly for plugging the casing of a well as in claim 1 in which said first end of the plug body includes a tapered portion that includes a first narrowing.

5. A plug assembly for plugging the casing of a well as in claim 4 in which said tapered portion includes an additional second narrowing.

6. A plug assembly for plugging the casing of a well as in claim 1 in which said bit includes knurl blades.

7. A plug assembly for plugging the casing of a well as in claim 6 in which said knurl blades are arranged with the direction of each knurl blade curving upward from the narrow tip on the base to the broad shoulder on the top of said bit.

8. A plug assembly for plugging the casing of a well as in claim 1 in which said bit rotates and spins on the first end of the plug body.

9. A plug assembly for plugging the casing of a well as in claim 8 in which said bit is attached to the first end of the plug body by a bearing assembly and a shaft for spinning rotation of the bit.

10. A plug assembly for plugging the casing of a well as in claim 1 in which said seal includes three spaced rubberized members attached to the circumference of the plug body and said rubberized members are flexible and compressible.

11. A plug assembly for plugging the casing of a well as in claim 1 in which said plug body includes a guidance system for guiding the plug assembly to a mouth of the casing.

12. A plug assembly for plugging the casing of a well as in claim 11 in which said guidance system includes a global position satellite receiver for transmitting the location of the plug assembly to a remote control station.

13. A plug assembly for plugging the casing of a well as in claim 11 in which said guidance system includes a magnetic guidance sensor for locating the plug assembly within the mouth of the casing.

14. A plug assembly for plugging the casing of a well as in claim 1 including a chain and said chain attached to the anchor and being a length measured for reinforcement of a sealant back-fill material and a sealant mound material capping the well.

15. A plug assembly for plugging the casing of a well as in claim 1 including a cable attached to the chain for temporarily tethering the plug assembly to a platform, ship or boom.

16. A method for plugging the casing of a well comprising the steps of:

a. providing an elongate plug body with a bit on a first end and an anchor with a chain attached on a second end to form a plug assembly;

b. suspending the plug assembly with the chain and a cable attached to the chain;

c. lowering and guiding the plug assembly to a mouth of the well casing;

d. inserting the plug body into the well casing a determined distance with the chain extending upward through the mouth of the casing;

e. pouring sealant material into the casing above the plug body to fill the casing, said sealant material being reinforced by the chain extending through the sealant material;

f. pouring a mound of sealant material over the mouth of the casing; and

g. detaching the cable.

17. A method for plugging the casing of a well as in claim 16 including an additional step of providing said bit with knurled blades and a further step of spinning the bit as the bit moves through water.

18. A method for plugging the casing of a well as in claim 16 including an additional step of using a global position satellite receiver or magnetic guidance sensor to position the plug body into the mouth of the casing.

19. A method for plugging the casing of a well as in claim 16 including an additional step of sealing the plug body within the casing after the plug body is inserted using a rubber seal near the second end of the plug body to fill a clearance gap between the plug body and an interior wall of the casing.

20. A method for plugging the casing of a well as in claim 16 in which said sealant material is concrete or cement.