US3417824A - Lost circulation restoring devices - Google Patents

Description

Dec. 24, 1968 H. K. VAN POOLLEN LOST CIRCULATION RESTORING DEVICES 2 Sheets-Sheet 1 Filed Dec. 26, 1967 mus/Wok HENDRIK K. VAN POOLLEN 2 Sheets-Sheet 2 INVENTOR HENDRIK K. VAN POOLLEN ATTORNEY Dec. 24, 1968 H. K. VAN POOLLEN LOST CIRCULATION RESTORING DEVICES Filed Dec. 26, 1967 United States Patent 3,417,824 LOST CIRCULATION RESTORING DEVICES Hendrik K. van Poollen, Littleton, Colo., assignor to Marathon Oil Company, Findlay, Ohio, a corporation of Ohio Continuation-impart of application Ser. No. 598,557, Oct. 10, 1966. This application Dec. 26, 1967, Ser. No. 693,504

Claims. (Cl. 166-117) ABSTRACT OF THE DISCLOSURE A device for restoring lost circulation in the drilling of a subterranean formation, the device comprising a plurality of sealed, flaccid, water-soluble bags containing lost circulation restoring materials, the bags attached in series to a water-insoluble rope strong enough to support the aggregate weight of said bags. The bags can be fitted one inside the other, the inner bag containing the lost circulation restoring materials and the composite being less water soluble.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser. No. 598,557, filed Oct. 10, 1966, now Patent No. 3,362,476.

BACKGROUND OF THE INVENTION Nature confronts the well driller with different types of lost circulation problems. Sometimes the drilling fluid is lost through minute fissures in rocks. At other times, the bit will drill into underground rivers. These rivers are swift or slow, and their beds fiat or sloping. Subterranean caverns as large as Mammoth Cave may be drilled into, where again, sloping floors may be encountered. Numerous solutions have been proposed to overcome these difiiculties. U.S. Patent No. 3,193,373 to Weathersby teaches a process wherein the drilling pipe is placed a short distance above a lost circulation zone in a well-bore, and rigid four-piece containers cast from water-soluble materials are injected alternately therein with mud and Water. Weathersby attempts to prevent the rigid containers from becoming lodged and prematurely blocking the well-bore by using the drill pipe as an external injector means. However, serious blocking can still occur in the drill pipe. Injecting such containers Without the protection of an injector means greatly increases the danger of blocking because of numerous rough and uneven spots where the rigid casings can snag and bridge the well-bore. One of the many advantages of the present invention is that such an injection means is not required. Also, this invention obviates the costly casting and threading of capsules such as Weathersbys cast containers.

Furthermore, Weathersbys containers are free to move away from the immediate well-bore vicinity, whereas in my invention, the bags containing lost circulation restoring materials are contained within that vicinity.

SUMMARY OF THE INVENTION nite, or like materials, and clamped at the other end to effect a sealed bag. Some formation conditions require that the bags remain intact for longer periods of time; namely, hot formations which cause the water-soluble material from which they are made to dissolve at a quicker rate. This problem is overcome by increasing the thickness of the water-soluble bags, e.g. by using multiple bags placed inside one another to effect a predetermined wall thickness. Composite bags can be effected which will dissolve only at the site of lost circulation.

The water-soluble bags are attached in series to a Water-insoluble rope which tends to contain the bags within the immediate vicinity of the Well-bore.

No great inventory of bags is required and a number of bags of one size can be fitted, one inside the other, as desired, and tightly clamped to form a protective device of needed water resistance for the particular conditions of a formation. In tubing form, the bags can be flattened and contained in a small package for shipment or warehousing.

The filled, sealed bags are securely attached to a waterinsoluble rope by any suitable clamps. A weighted object may be attached to the terminal end of the rope to 'act as an anchor at the bottom of the formation.

DECRIPTION OF THE PREFERRED EMBODIMENTS The water-soluble bags of this invention can be made out of many materials. For example, they may be composed of a polymer film of polyvinyl alcohol, ethylene oxide, polyethylene oxide, dextran, gelatin, methyl cellulose, or the like.

Circulation restoring materials known to the art may be utilized, e.g. dry neat cement, dry bentorn'te, etc. These filler materials may be modified with quick-setting agents, weight-controlling agents, and reinforcing solids, all of which enhance the utility of the invention.

Any water-insoluble rope which satisfactorily supports the aggregate Weight of all the filled bags aflixed thereon is useful. Such ropes include metallic ropes, and nonmetal ropes composed of natural and synthetic fiber. Example of a metallic rope is a steel wire. A rope made of hemp typifies the natural fiber rope, whereas a rope composed of nylon or polyester typifies a synthetic rope.

The attached drawings illustrate my invention. In the attached drawings:

FIGURE 1 is a cross sectional view of a filled bag.

FIGURE 2 depicts a plurality of bags fitted one inside the other, and wherein the innermost bag is filled with circulation restoring materials.

FIGURE 3 is a cross sectional view of a Well-bore showing a plurality of Water-soluble bags attached in series to a Water-insoluble rope descending into a formation and falling into place around a weighted object at the terminal end of the rope.

FIGURE 4 shows an integral mass which has set in place at the site of lost circulation within the formation.

FIGURE 5 depicts a drill bit passing through the integral mass; lost circulation has been restored.

FIGURE 1 shows bag 2 filled with cement 12 and sealed at the top by clamp 8 and at the bottom by clamp 10. The filled bag is attached to water-insoluble rope 14 by clamps 8 (at and 10 (at 10a).

FIGURE 2 shows a plurality of bags fitted one inside the other. Bag 2 is fitted inside bag 4 and bags 2 and 4 fitted inside outer bag 6. Bag 2, the innermost bag, is filled with dry cement 12. All the bags are sealed at the top by clamp 8 and at the bottom by clamp 10. The composite bag is attached to Water-insoluble rope 14 by clamps 8 (at 8a) and 10 (at- 10a).

FIGURE 3 shows a plurality of bags of various sizes descending through borehole 32 into a large, sloping subterraneau formation 16. Larger bags 20 form a retaining means for latter, smaller bags 22, 24 and 26, these bags being of different sizes to fill the interstices between larger bags 20. This particular embodiment, combined with heavy weighted object 18 (anchor) attached to the terminal end of water-insoluble rope 14, tend to contain the bags in the area of lost circulation.

In FIGURE 4, the bags have dissolved and water has mixed with cement released from the dissolved bags (e.g. cement 12) to form an integral mass 28 within formation 16.

In FIGURE 5, mass 28 has hardened. Drill bit 30 is shown boring its way through mass 28; lost circulation within formation 16 has been restored. Well-bore 32 continues through formation 16.

It should be understood that the invention is capable of a variety of modifications and variations which will be made apparent to those skilled in the art. Such modifications and variations are to be included within the scope of the invention.

What is claimed is:

1. A device for restoring lost circulation in the drilling of a subterranean formation, the device comprising a plurality of scaled, flaccid, water-soluble bags attached in series to a water-insoluble rope strong enough to support the aggregate weight of said bags when filled with lost circulation restoring materials.

2. The device of claim 1 wherein a weighted object is attached to the terminal end of the rope.

3. The device of claim 1 wherein a plurality of scaled, flaccid, water-soluble bags are fitted one inside the other to obtain a composite bag having limited water solubility characteristics.

4. The device of claim 3 wherein the composite bag is water soluble at the site of lost circulation.

5. The device of claim 1 wherein the bags closer to the terminal end of the rope are larger than the bags far removed from the terminal end.

6. The device of claim 1 wherein the water-insoluble rope is a metallic rope.

7. The device of claim 1 wherein the water-insoluble rope is a non-metallic rope.

8. The device of claim 1 wherein the water-insoluble rope is a synthetic fiber rope.

9. The device of claim 1 wherein the bags are composed of a polymer film of polyvinyl alcohol.

10. The device of claim 1 wherein the bags are composed of a polymer film of polyethylene oxide.

11. The device of claim 1 wherein the bags are composed of a polymer film of cellulosic material.

12. The device of claim 1 wherein the bags are composed of a polymer film of dextran.

13. The device of claim 1 wherein the bags are composed of a polymer film of gelatin.

14. The device of claim 1 wherein the lost circulation restoring materials are comprised of dry bentonite.

15. The device of claim 1 wherein the lost circulation restoring materials are comprised of cement.

References Cited UNITED STATES PATENTS 2,504,462 4/1950 Sprague et al 166-179 X 2,609,880 9/1952 Dyer 166-21 2,634,098 4/ 1953 Armentrout 175-72 2,748,867 6/1956 Lissant 166-42 X 2,768,693 10/1956 Hughes 166-21 2,824,611 2/1958 Burch 166-57 3,190,373 6/1965 Weathersby 166-117 X 3,362,476 1/ 1968 Van Poollen 166-21 STEPHEN I. NOVOSAD, Primary Examiner.

US. Cl. X.R.

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