US2341572A - Method of drilling wells - Google Patents

Description

Feb. 15., 1944;

3 Sheets-Sheet 1 7 I v l /4 8 I u w L I /3 g MWdfZ/Z-iPed- Feb. 15, 1944. H. L. REED METHOD OF DRILLING WELLS Filed Dec. 4, 1936 3 Sheets-Sheet 3 Patented Feb. 15, 1944 METHOD OF DRILLING WELLS Howard L. Reed Houston Tex. assignor of eleven and one-third per cent to Fdhs Oil Company Application December 4, 1936, Serial No. 114,098 3 Claims. (01. 2255-18) This invention relates to a method of drillin wells.

It is customary in drilling wells and similar I bore holes in the earth to utilize a boring tool of some suitable type for the purpose of forming the bore hole, and to circulate through the bore hole during the drilling operation a fluid which serves to remove the cuttings from the hole, as well as for a number of other purposes.v

Among the purposes of this fluid is to provide a means of holding back or supporting the walls of th bore hole and preventing them from caving in. Another purpose of this fluid in present day practice is to provide a seal for preventing the influx into the well ofgas or fluid which may be contained in a formation encountered, and thus to prevent the well from flowing until such time as may be desired.

In the past, the fluid most commonly used for thispurpose has been a type of mud which contains certain chemical substances that render it of Sllfiicient weight to'properlycontrol the pressures existing within the various formations. However, it has been experienced that when this mud-is placed under suflicient pressure to force it into the various formations ncountered, it not infrequently solidifles within such formations and after such solidification cannot be removed so as to permit the well to produce when production is desired. It has further been experi-' enced that there are certain types of formation with which certainJof the ingredients used in this mud will have a chemical reaction causing a great swelling within the walls of the bore hole and caving in ofthe well hole. It is a known fact that what might have beenval'uable wells have been lost in this manner, and in many instances great expense has been involved because of such accidents.

It is an object of this invention to provide a method of drilling a well in which a. fluid will be utilized which will positively prevent caving of the formation, and which will at the same time form a positive formation seal capable of ready removal.

It '7 a further object of this invention toprovide a method of drilling a well in which a casing and other pipes necessary to be placed within the ;well for production purposes may be placed 1. 5o therein-without the trouble and expense involved inrthe ordinary method of cementing in place.

Another object of this invention is to'provide of the bore hole may be rendered substantially solid and impervious.

Another object of this invention is to provide a method of drilling a well in which the heat conductive characteristics of the formation being drilled may be readily determined.

Another object of this invention is to provide a method of drilling a well in which the horizontal position of the lower end of the well may at all times be determined.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which like numerals indicate corresponding parts throughout. It is to be understood that said description and drawings are by way of illustration only, and are not to be taken as in any way a limitation upon the scope of this invention. Such limitation is to be only by the prior art, and by the terms of the appended claims.

In the drawings:

Fig. l is a view partly in vertical cross section illustrating the upper part of a well being drilled according to the method of this invention.

Fig. 2 is a top plan view illustrating diagrammatically the equipment utilized atthe surface of the ground during the drilling of a well in accordance with this invention.

Fig. 3 is a view in vertical cross section illustrating the lower portion of a well which has been drilled according to the method of this invention.

Referring first to Fig. 1, the numeral l indicates the supports for the. derrick floor 2 and for the derrick legs 3, which parts are of -substantially the same construction as in ordinary practice. Likewise, the numeral 4 illustrates the table of a rotary machine and the numeral 5 the base of such machine, which is utilized for rotating the drill stem during the drilling operation. The numeral 6 designates the upper section of the drill stem ordinarily known as the Kelly joint, the same being of non-circular cross section and adapted to be rotated by the rotary machine just referred to. To the lower end of this Kelly joint 6 is secured the upper end 1 of the drill stem proper, upon the lower end of which is mounted the drill used in drilling the well.

After the bore hole has been started and has progressed for a relatively short distance, there is positioned within the upper end of the same what is known as a surface string of pipe 8 which is of substantially the same outer diameter as the inner diameter of the bore hole. At the upper end of the surface string 8 there is provided a second string of pipe 9 of such a size as to leave an annular space outside of the string 9 and within the surface pipe 8. At their upper ends, both the strings 8 and 8 are externally threaded to receive a fitting l having an opening at one side thereof to which allow line H may be connected in communication with the annular spacebetween the surface string 8 and the pipe 8, and having also an opening adapted to receive a flow line H communicating with the interior of the pipe 8. It will be seen that the pipe 9 is of shorter length than the surface pipe 8, and a seal I2 is preferably formed between these pipes in the lower end of the pipe 9 thus closing the lower end of the annular space I 3 formed between these pipes.

Within the pipe 8 there is lowered into the wella casing I 4 which may be of conventional construction, and a seal it is provided between the lower end of the pipe 9 and the outer wall of the casing. This seal I5 is in the form of an annu- .ar packing which bears against an inwardly extending flange IS on the pipe 8, and is compressed oy means of a gland nut ll threaded into the Lower end of the pipe 9. It is to be noted that the pipe 9 Just above the seals l2 and] I is formed with a plurality of openings 18 therethrough.

At the upper end of the casing, the same is ex- ;ernally threaded into the lower end of a flow head l0, this flow head is being threaded into the in- :erlor of the upper end of the fitting l0 so as to form a closed annular space between the pipe 0 and the casing I4. The flow head II is provided with a lateral outlet 20, and at its upper end is nounted a stuillng box of a type adapted to receive ahe externally square Kelly joint 8.

The stuiling box just referred to consists eslcntlally of a stationary ring 2| mounted within the upper end of the flow head. a Packing 22 :eated thereagainst, and a ring 23 adapted to bear igainst the upper end of the packing and cause .t to form a seal with the inner wall of the flow read. A nut 24 serves to force the ring 23 downvardly against'the packing 22. Threaded into she upper end of the ring 23 is a bearing race 25 idapted to receive anti-friction bearings 26 which :1 turn rotatably support a sleeve 21 having exernal bearing races 28 thereon. In order to prerent leakage past thissleeve and bearing, a pair vf stuffing boxes 29 and 30 are provided at the lpper and lower ends of this sleeve,-respectively. i'he lower end of the sleeve 21 is provided with an uwardly extending flange 3| adapted to support l ring I! which is preferably of square internal rross section. Supported upon this ring 32 is a lacking 33,9. ring 34, a packing 35, and a ring I. The packings 33 and fare compressed beween the respective rings by means of a nut 31 breaded into the upper end of the sleeve 21.

At the lower end of the drill stem I there is conlected a drill which in this instance is illustrated s an expansible bit 38. During the drilling opration there is circulated through the well a fluid rhich is preferably a relatively pure molten sulhur. This sulphur is flrst heated within a pit I at the surface of the ground by means of steam oils supplied with steam through a pipe 4|. .hese steam coils have a discharge pipe 42 hrough which the condensate from the steam is onducted back to the boiler. As the sulphur in he pit I! is brought up to the desired heat, it is rawn from this pit through a pipe 43 by means f a pump 44 which is preferably of the centrifual variety. It is to be noted that upon being felted, sulphur becomes very fluid, the viscosity eing very low indeed, so that the material will flow substantially the same as water. This pump as maycbe driven in any suitable manner as by means of some power force through the pulley 4E and the discharge from this pump is conducted through a pipe 48 and through the customary hose connection to the interior of the Kelly joint 8. Thus it is forced downwardly into the well through the drill stem and allowed to arise to the top of the well again through the space surrounding the drill stem within the casing. After the well has been drilled to a suillcient depth to permit the insertion of the surface string 8 and the pipe 9, the same are put in place together with the stufling box thereon, and the sulphur retuming from the bottom of the bore hole may be heated to facilitate its flow from the well by forcing steam into the space between the pipe 0 and the casing l4, and causing the same to circulate downwardly around the outside of the casing and upwardly through the annular space It, the exhaust passing out through the pipe II.

It is to be noted that sulphur has a considerable density so that the hydraulic head thereof at any given depth would be substantially greater than the hydraulic head provided by the muds ordinarily used for circulation during the drilling of a well. Thus, the'well could be kept under control and fluid and gas from the formation could be prevented from entering the well even more effectively with molten sulphur than with ordinary drilling fluids. However. in order to impregnate the walls of the formation on all sides of the bore hole with molten sulphur. it is desirable at times to increase the pressure upon the sulphur to force it into the formation. when this is desired, the flow bean 41 is interposed in the sulphur discharge line H and is utilized to throttle down the flow of sulphur from the well, thus building up pressure within the well.

As the well is being drilled, sulphur will, in view of the foregoing be forced into the formation to some extent such as indicated for instance by the numeral 48 in Figs. 1 and 3. It will also pass beyond this line wherever crevices or openings occur as indicated at 40. In view of the relatively high melting point of sulphur, the same will on passing into the formation be cooled below its melting point and caused to solidify. This. it will readily be seen, will, so to speak. solidify the formation itself, and where this formation consists of what is ordinarily known as heaving shale, the same will be positively prevented from caving in. Also, it will be protected from contact with water or water-bearing substances which might later otherwise come in contact therewith and whichwouid cause the so-called heaving shale to swell, cave in, and probably ruin the well.

In addition to the foregoing, it will be seen that as the drilling proceeds below the lower end of the surface string 8. the molten sulphur will tend to solldifyupon and around this surface string, thus firmly anchoring it in place. Likewise. after the drilling has proceeded to the upper surface of a producing formation, and it is desired to anchor the casing and drill into the producing formation, this may be accomplished by simply permitting the sulphur surrounding the casing to harden. It will readily be seen that-this will not only anchor the casing and form a positive seal between the casing and the formation, but that it will also form a sealwithin the formation itself and render it impervious to water andother fluids.

with further regard to the anchoring of the casing by means of permitting the sulphur to solidify, it may be explained that this can .be accomplished in any one of a number of different ways.

For instance, as soon as the oil sand is penetrated, the bit may be withdrawn and the sulphur forced from the interior of the casing by placing a plug in the upper end of the casing and pumpin: it downward with heated oil or mud. Sufflcient time is then allowed to permit the sulphur around the casing to solidify and the drilling of the well may then proceed in the customary manner. -That is to say, an expansible bit will be lowered through the casing and the drilling into the producing formation will be continued, using either oil or the customary drilling mud as a circulating medium. If oil is to be used, there must of course be some means of controlling the well and maintaining a pressure upon this oil in order that a blow-out will not occur. After the well drilling has been completed, the well may be tested and operated in the ordinary manner.

Another method would be to continue the drilling after positioning the casing at the point desired, and to pump into the. drill stem a superheated mud, permitting this mud to wash downwardly through the drill stem and up through the casing until all the sulphur has been displaced from the casing. The temperature of the mud may then be reduced andthe sulphur surrounding the casing permitted to freeze and anchor the casing in place.

If after the casing has been set it becomes desirable to move the casing either upwardly or downwardly, it will be seen that this can be readily accomplished by simply circulating a mud or similar substance through the casing until it is heated up sufficiently to permit it to move through the sulphur which surrounds it. This makes it possible to make a production test at one or more points in the well, andto make these production tests of any duration desired, in order to determine how the well will behave after it has been in production a short time. It is also noted that this feature enables the eventual recovery of the uncorroded casing after the well has ceased to produce, thus involving a considerable saving in the cost of the casing. During the production of the well it may also be adjusted to any position which may seem desirable in accordance with the changing characteristics of the well. The sulphur may also be melted to permit movement of a casing or drill pipe by applying a low voltage, high frequency alternating electric potential between the pipe and the surrounding formation.

- and thus in a considerable measure to determine the actual make-up of the formation by simply observing the differences between the temperature of the sulphur as it enters the well and the temperature of the returning sulphur. It will be seen for instance that if a formation is encountered such as a salt water sand, which has high heat conductive properties, the temperature of the returning sulphur will suddenly drop, and that if an oil sand is encountered, which will not conduct heat readily, the temperature of the returning sulphur will not drop as much as for other formations. This difference in temperature readings must of course be corrected for various known factors such as the increased depth of the well, etc., but it will readily be seen that these may be determined and the result desired may be found with little difllculty.

In addition to the foregoing, it is contemplated by this invention that sulphur or other high temperature fluid may be circulated through a well until the temperature becomes substantially constant from the top to the bottom of the well. and then allowed to stand for a. predetermined period. The temperature of the circulating medium will then be taken at various points in the well and the drop in temperature at each point will serve to indicate the thermal characteristics of the surrounding formation. It is noted that this test may be made either in the open hole or after the casing has been set. In the latter case, it is particularly useful in determining the position of the top of the sulphur Or other seal about the casing or any source of water channeling which exists behind the pipe.

It is further to\be noted that inasmuch as the sulphur is a fairly good heat insulator and solid sulphur is one of the best heat insulators known, the temperature thereof may be held up fairly well and the portion thereof which enters the formation and which cools upon the walls of the borehole will serve to insulate the remainder thereof. It is also to be noted that the specific heat of the sulphur is comparatively low, and that it will, therefore, require less heat to raise a given quantity of sulphur to the desired temperature than with some other circulating medium.

Attention is directed to the fact that sulphur is also a good electrical insulator, thus making it possible during the drilling operation'to conduct electrical surveys which would not otherwise be feasible. For instance, it is possible to determine with a fair degree of accuracy the horizontal position of the lower end of the well by connecting to the drill stem one pole of an electric power supply and connecting the other pole to an electrode which may be shifted from one point to another on the surface of the around until the point of least resistance between the lower end of the bit and such electrade is located. This point will ordinarily designate the horizontal position of the bit itself. This also makes it possible to note variations in resistance between the drill stem and a point on the surface of the ground to obtain the electrical characteristics of the formation being drilled.

.Also, with the casing and other equipment insulated from the walls of the hole, it is possible to impress an electrical potential, usually negative, on such equipment for the purpose of preventing corrosion.

In view of the foregoing, it will be noted that there has been provided a method of drilling a well wherein the disadvantages inherent in previous methods have been eliminated and wherein all of the objects and advantages sought by this invention may be realized. It is to be understood that while it is primarly intended that the step of anchoring the casing within a well shall be carried on in connection with the drilling of the well by this method, such anchoring of the easing-is not limited to this method alone. instance, it is within the spirit of this invention to drill the well in the ordinary manner using customary drilling fluids, and to anchor the casing therein by forcing molten sulphur into the well in a manner similar to that now employed for forcing cement into the well. After the casin has been thus anchored, it may of course be re- For moved in the same manner above described, or the drilling may proceed in the miller way. Having described my invention. I claim: 1. lnemethodoidrlllingnwelhthestepsot rotating a. drilling tool to form at bore hole. and b hole, circulatlnl molten sulphur throuzh said bore 10 hole durine the drilling operation. and cousin: a portion of seid'sulphur to impregnate the wells 0! seidboreholee-ndooolthereintorendereeid wells eeli-lupportini.

3. The method oi drilling o well which comprises circulating through the well while drilline the some a liquid dielectric lubetnnee eubetnntielly solid at atmospheric temperetures, and eppiying a low voltage high frequency alternating electric potential between the round adjacent said hole and an electrical conductor therein to supply heat to said substance.

HOWARD 1.. am.

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