US2110236A - Method of drilling and sealing oil wells - Google Patents

Description

March 8, 1938. w NOLAN 2,110,236

I METHOD 0 DRILLING AND SEALING OIL WELLS Filed Nov. 19, 1957 2 Sheets-Sheet l 8, w NOLAN 2,110,236

METHOD OF DRILLING AND SEALING OIL WELLS Filed Nov. 19, 195'? 2 Sheets-Sheet 2 Patented Mar. 8,1938

UNITED STATES PATENT, OFFICE William E. Nolan, Kermit, Tex.

Application November 19, 1937, Serial No. 175,505

1 Claim.

This invention relates to methods of drilling and sealing oil and gas wells, and among other objects, the invention aims to provide a method which will effect very important economies in the cost of completing an oil or gas well. Other objects will appear from the following description of the preferred method and equipment used in connection therewith.

In the accompanying drawings showing diagrammatically an oil well and said equipment,

Fig. 1 is a vertical sectional view showing the drilling in progress;. and

Fig. 2 is a similar view on a larger scale, but showing only the lower part of the'pit andshowing the effect of heating the walls of the well and low the standstone, a second stratum of limestone M below the shale, and a second stratumof sandstone l5 below the shale which will yield gas or oil or both, often under enormous pres-' sure. In accordance with the invention, a pit I 30 I6 is first dug deep enough to reach the upper part of the limestone stratum ll nearest the surface, and large enough to permit the workmen to descend and work in the pit with the various tools and equipment during the drilling and 35 sealing of the well. A heavy floor I'I, preferably of reinforced concrete, is built at the bottom of the pit to seal the same and prevent gas pressure from lower strata destroying the pit and the equipment therein.

40 Extending through the bottom of the floor I! is a heavy casing lllwhich is sealed by the floor and which is connected to a cut-off valve l9 controlled either from the pit by a hand wheel or from the base of derrick 2| by a rod 22 45 connectedto a crank 23. An .air pump 24 driven by a motor (not shown) is connected by pipe 25 to casing l8 below the cut-off valve, as shown, and a check valve 26 is provided in the pipe line 25 to check the back pressure.

50 The drilling is effected eitheigby a rotary drill (not shown) or a churn drill 21' suspended from a cable 28 which is reciprocatecl by a well-drilling machine (not shown) or by a motor-operated walking-beam 29. During drilling, a heavy air pressure is maintained in the excavation by means of the pump 24. The casing 30 which extends above valve I9 (which must be open during actual drilling) is provided with a packing head 3|, of known construction, to hold the air pressure.

As the drilling proceeds, the limestone stratum II is penetrated and the top of the stratum of Water-yielding sandstone is reached. At this time the drilling tool is withdrawn, and an electric heating element is introduced into the bore. As 10 shown in Fig. 2, the electric heating element comprises a thick walled, hollow, metal core whose diameter is only slightly less than the diameter of the bore, so that as the core is lowered, it will come in contact with the walls of the 15 bore substantially throughout the entire-surface thereof, except for.the small voids and spaces I left in the rock walls by breaking off of rock fragments by the drilling operation. The metal core 35 is provided with electric heating means, 20 which may be a plurality of resistance elements (not shown) enclosed by the core, or an electric are 36 maintained by terminals 31 which are electrically connected to a source of current by a cable (not shown) enclosed by and insulated 25 from a rope or cable 38 which raises and lowers the core. A transformer 39 located at any convenient point, delivers current at the proper voltage and amperage to the terminals 31 or to the resistances, and a switch 40 permits the cur- 4 rent to be turned off, as when the core is being hoisted by a motor-driven drum 4|. The transformer 39 may have its points changeable (as is known in the art of transformer making and hence requires no illustration) so that the voltage may be increased as the cable 38 is lengthened, to compensate for the copper loss. The cable 38 will be provided in sections which may be mechanically and electrically connected, end to end. 40

It will be understood that under the intense heat of the electric are or of the resistances, the core will become extremely hot, and as it comes in contact with the walls of the bore, it will melt or coalesce the walls and will form (in certain materials) a glass-like, hardened surface with an altered or metamorphosed area surrounding said surface (indicated by darker areas 42 in the drawings, Fig. 2) which will prevent seepage of water through the pores of the rock into the bore, and thus will seal the bore. In shale strata, such as l3, where caving may occur unless the walls of the bore are artificially strengthened, the heat of the core is effective to melt and coalesce the surface of the bore and to metamorphose the areas for at least several inches in all directions around the bore, so that the rock during the entire drilling operation is, of course,

' previously mentioned, completes the sealing of;

essential to the success of the method, as such pressure will hold back the water until the bore is sealed and will aid in preventing caving.

As there cannot be perfectfl'contact between the surface of the heated core and the irregular surface of the bore, the sealing effect, described above, will necessarily be imperfect and undependable in the absence of a sealing medium. In accordance with the invention a layer of sulphur, or sulphur and lime, or a similar mixture or material, is spread over the entire surface of the bore by being poured or dumped through the casings 30, I8 ontop of the heated core'35, which is reciprocated to aifect a plastering or spreading of the sealing material. The heat melts the sealing material and the core and air pressure complete the operation. The result is an inner layer or skin 43 of sealing material which, in conjunction with the metamorphosed walls and areas the bore, and further strengthens the walls of the bore against caving. j

I The described process continues with alter-- nate drilling and sealing, ,until: the gas or oil bearing stratum iszreachedjwhenfthe drilling op- 35 eration'may'eease.-, Thefusual casing (not shown) may no-w;I-:he ;applied in the usual manner, as it will be' eco'nomically justified'flfor some wells.

After the casing is in place, pthegair pressure may be cut off, and the well F'w'ill be in production. However, in" some cases the well may be put into walls of the uncompleted well by gas or oil flames burning from. the core, which may be supplied with gas or ,oilthrough a flexible conduit (not shown). The" necessary oxygen for combustion is supplied by the air supplied under pressure by the air pump, as described.

Obviously many other changes in the described apparatus may be made, and some modifications in the described process may be resorted to, within the scope of the appended claim.

Having described the preferred method of the invention, what I claim as new and desire to secure by Letters Patent of the United States of America is: v I

, A method of drilling and sealing oil or gas wells comprising, first, digging a pit to a relatively impervious formation and sealing the bottom of the pit; then drilling for a limited distance below the bottom of the pit with the bore constantly maintained under high air pressure; then heating the walls of the bore to metamorphose the material of the walls for some distance around the bore, simultaneously coating an easily melted material which isnot aifected by crude petroleumover the surface of the bore to provide a sealing skin or layer therefor; continuously' maintaining said high air pressure during the heat metamorphosis and sealing of the walls and adjacenqareas; and alternating further periods of drilling with successive periods of sealing in the manner described.

WILLIAM E. NOLAN.

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