Technical Publication No. 633 (C~aas C, IRON AD STEEL DIVIEION, NO. 136; INETITUTE OP METALE DIVIEION, No. 194)

DISCUSSION OF THIS PAPER IS INVITED. Discussion in writing may be sent to the Secre- tar .American Institute of Mining and MetaUur 'cal Emxinee?. 29 We& 39th Street, New York. N..Y. UJBBB a eclal arrangement ~8 made, dm.cuas~on oythia paper WIU dose Bept. 16. 1836. Any discussron gflered tiereafter should preferably be In the form of a new paper.

Some Mechanical and Metallurgical Aspects of Present-day Oil-production Equipment

(New York Meeting. February, 1936)

ACCORDING to recently published statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year.

Were i t not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in.the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the applicatiog of scientific drilling methods and the adaptation of modern equipment-and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet.

Modern rotary drilling tools are the product of ingenious design and careful selection and adaptation of materials used in their construction. They must withstand teriific abrasion and, because of their compactness, must be designed to resist exceedingly high unit stresses. In bits, core drills and reamers, the bodies are made of either forged or cast alloy steels, heat-treated to develop a combination of high strength and tough- ness. To provide sufficient strength to the threaded portions and to protect the threads from distortion or damage, the box or pin sections of the tools are hardened to approximately 310 to 330 Brine11 hardness

Manuscript received at the office of the Institute March 25, 1935. * Development and Research Dept;, International Nickel Co., New York, N. Y.

1

Copyright. 1936, by the American Institute of Mining and Metallurgical Engineera, Inc. Pnnted in U. 8. A.

August, 1936

I9

TABLE 1.-Some Alloy Steels Used in Various Parts of Oil-production Equipment

Part

I I Typical Mechanical Properties

Steel Yield Tensile el on^. Red. of Brine11 Izod

Strength Hard- m act I L b ~ ~ ~ l n . L b . . / S g . I n . '7;) 1 % neas :t.%be. ------

Rock drill and reamer cuttera, fishing tape, High surface hardness S.A.E. 3115, carburized: slip inserts. Reamer and d r i cutter plna for wear reelstance, 1475' F., oil quench 126.000 166.000 13 43 335 30 are somet~mes made of theae steels. tough shock-resisting 1550' F oil quench

core. 14000 F:: oil quench) 85,000 125,000 25 65 255 65 ---- S.A.E. 4016, carburised: 1525' F., oil quench 105,000 145,000 300 36 1 ::: 2; :$:::] 75,000 1 110000 2 21, 75 ----

S.A.E. 2316, carburised: 1475' F., oil quench 136,000 100,000 346 36 l o Oi luench 00,000 1 96,000 :: :: 1 196 1 86 1375' F:: oil quench]

Rotary machine geara.

Bodies for drills. reamers. caaina oerforators. miecellaneous *ling and.. rfishing-tool forenm, tool joints, dnll coUara, kellys. plston rods for slush pumps, m~scellaneoua shafting for draw works,-eta.

Bodies for jam and miscellaneous fishing tools.

- S.A.E. 2315. single =&$/ sz;;ped aa deacribed

High stren h together S.A.E. 3140, oil- wlth g o o 2 toughness quenched a t 1475- and fatigue ropertiea. 152K0 F., and tempered ~n ieces o r medium at: ancfheavy eectidn. , 900' F.

1000° F.

High im act and tensile S.A.E. 2340, oil- strengtL, particularly quenched a t 1400- in heavier sections. 1450' F.. tempered at:

900° F. 1000° F.

Wall-scraper blades, fishtail blades.

Reamer and drill cutter pins, rotary machine geara and pinions.

High hardness and S.A.E. 4140. 3140. 60 300 60 strength. quenched and

pered.

High hardneas with S.A.E. 3250.4060.0150, 45 400 25 toughness. oil-quenched and tem-

pered. 33 500 8

ALBERT G . ZIMA 3

number. Drill and reamer cutters are generally of the movable type; i.e., serrated cones, cylinders or disks, which can readily be replaced when worn out. Usually, these cutters are-machined from low-carbon nickel- alloy steel forgings and subsequently case-hardened to impart the neces- sary wear resistance. The cut tersare mounted by means of suitable bearings upon axles or pins and in this manner attached to the body. These pins are also made of alloy steel hardened to a high degree to provide wear resistance. Some manufacturers use oil-hardening steels for the pins while others use the low-carbon carburidng types such as those used for the cutters. In either case, it is necessary to produce a pin having high surface hardness (65 to 80 sclerescope) for wear resistance and sufficient strength and toughness to with- stand the high stresses encountered in service. Fishtail bits used in soft-formation drilling are equipped with stationary cutters or blades made of forged or cast alloy steel protected with a hard surfacing material.

Typical properties of several alloy steels used in various parts making up rotary drill P i t and reamer assemblies are .shown in FIG. 1 . - R O L L E R - B E A R I X G ROCK BIT.

(Courtesy Reed Roller Bit Co.) Table 1.

Figs. 1 and 2 illustrate two of the latest types of rock bits. I n Fig. 1, note particularly the manner in which the cutters are mounted on roller bearings. Fig. 3 illustrates a pilot bit. In service, a rock bit of smaller diameter is attached to the lower end. Fig: 4 shows the arrangement of cutters on a core bit. At the right of the photograph is shown a specimen of a rock core removed by one of these bits.

Among the recent developments in rotary drilling tools is the col- lapsible bit, like that shown in Fig. 5. This type of bit is best adapted for drilling in regions where soft formations predominate. The develop- ment is important from the standpoint of time saving, as i t makes pos- sible the changing of bits without removing the drill stem from the hole. In changing bits attached in the ordinary manner; from 6 to 10 hr. and sometimes even more is required to remove the drill stem from the hole, replace the bit and complete the "round trip" before resumption

4 PRESENT-DAY OIL-PRODUCTION EQUIPMENT

of drilling. With the collapsible bit, dull blades have been renewed a t depths below 9000 ft. in less than 1% hr. In service, the assembly is lowered through the drill stem, by means of a wire line, until it reaches the bit head a t the bottom where the blades automatically open out to the size of the hole being drilled and lock into position. When the bit becomes dull, an overshot-a device fitted with specially shaped jaws or clamps-is lowered through the drill stem on a wire line until i t engages a spearhead on the top of the bit carrier, and the whole assembly is then brought to the surface.

Fig. 6 illustrates another recent improvement in well drilling equipment; namely the core-taking fishtail bit, with which a core can be taken in soft formation while drilling a full-sized hole. I t is

FIG. 2. FIG. 3. FIG. 2.-HUGHES THREE:CONE ROCK BIT. ( ~ O U T ~ ~ S Y Hughes Tool CO.) FIG. 3.-PILOT BIT. (Courtesy Hughes Tool Co.)

not necessary to remove the drill stem and bit from the hole to obtain the core, as the core barrel is brought to the surface through the drill stem by means of an overshot attached to a wire line. The "fish-tail" blades are made of alloy-steel drop forgings, hard-surfaced with tungsten carbide, heat-treated, and then welded to the alloy-steel bit body.

In all of the tools just described, compactness without impairment of strength or drilling efficiency is achieved through careful selection and heat-treatment of alloy steels.

ALBERT G. ZIMA 5

. 4.-ARRANGEMENT OF CUTTERS ON HUGHES CORE BIT. ( C o t ~ r L e ~ y Hugh~2.s Tool Co.)

I FIG. 5.-"WIRE-LINE" DRILLTNG BIT. (Courtesy Reed Roller Bit Co.)

6 PRESENT-DAY OIL-PRODUCTION EQUIPMENT

The use of long kellys has certain advantages, which are obvious to those familiar with rotary drilling practice. A considerable saving of time is effected through the use of a long kelly, since fewer interruptions of drilling for making connections to drill pipe are required than when a

Co.)

short kelly is employed. Fig. 7 illustrates a 7 by 7-in. Kelly 55 ft. long, recently developed by the Baash-Ross Tool Co. of Huntington Park, Calif. These pieces are forged from a medium carbon alloy steel and a 4-in. dia. hole is bored from end to end. When gaging the ac-curacy of the bore, a 31x6-in. dia. bar 6 ft. long must pass through the forging without difficulty. The ends of the stem are upset to 9-in. dia. rounds, thus providing a joint equal -in strength to the square body. These ends are separately heat-treated to provide the proper degree of strength and hardness for the threads.

ALBERT Q. ZIMA 7

The 7-in, drill collars shown in Fig. 8 are also 55 ft, long and like the l<ellys, have a 4-in. dia. hole bored from end to end with the sa.me degree of accuracy. Six feet of the lower end of each collar is upset to 73%-in. dia. and the threaded ends are separately heat-treated.

During the early history of rotary drilling, no attempt was made to standardize dimensions or design of tool joints, and as the stresses encoun- tered were not severe, metallurgical specifications were not considered important. As the industry progressed, however, heavier equipment was adopted and deeper wells were drilled, with an accompanying increase in tool-joint failures. The use of a plain 0.30 to 0.40 carbon steel, heat-

I- - s=.. ...-- FIG. 'I.-SQUARI? KELLY, 55 FT. LONG, 7 BY 7 INCHES. ( C O U T ~ ~ S ~ Baash-~<OSS T O O ~ CO.)

treated to approximately 200 Brinell, was probably the first step toward improvement. To satisfy the requirements of present drilling practice, however, alloy-steel tool joints are used almost universally. The machined forgings are oil-quenched and tempered to a Brinell hardness of 310 to 330, to provide strength and sufficient hardness of thread to prevent galling or seizing.

The availability of reliable alloy steels has contributed much to the success and practicability of the full-hole tool joint (Fig. 9). At the time the full-hole joint was first offered to the industry, it was intended pri- marily to accommodate the use of collapsible drilling bits like those described earlier in this paper. Although the advantages of unrestricted flow of drilling mud were noted, this feature was not fully appreciated at that time. However, as drilling speeds were increased and deeper wells were produced, the importance of increased mud circulation as a material aid to rotary drilling was recognized. Larger pumps, capable of handling

8 PRESENT-DAY OIL-PRODUCTION EQUIPMENT

greater volumes of fluid a t higher pressures were adopted and with this i t soon became evident that removal of tool-joint restriction to mud flow was very desirable. Today, many thousands of full-hole tool joints, made from carefully selected alloy-steel forgings and heat-treated to insure the proper degree of hardness and the utmost in strength and toughness are in successful service.

FIG. 8.-DRILL COLLARS, 55 FT. LONG, 7 INCEES OUTSIDE DIAMETER, 4 INCHES INSIDE DIAMETER. (Courtesy Baash-Ross Too2 Co.)

Typical mechanical properties of test specimens cut from heat-treated S.A.E. 3140 tool joint forgings, are as follows: yield point, 115,000 lb. per sq. in.; tensile strength, 130,000 lb. per sq. in.; elongation in 2 in., 21.0 per cent; reduction of area, 60.0 per cent; Brine11 hardness, 328.

Tool-joint failures often can be traced to causes that might have been avoided through proper precautions. During a recent survey by the author, among several Texas oil producers, i t was found that galling and seizing of tool joints rarely occurred where care was taken to clean the threads and lubricate them properly before making up a string. A few cases of galling were traced to improper heat-treatment of the finished pieces, resulting in slight decarburization of the surface metal., Labora-

ALBERT G. ZIMA 9

tory tests conducted on specimens of the box and pin sections of one of the defective joints showed that by recarburization of the surface by means of a cyanide treatment and subsequently tempering to 310 to 330 Brinell, the tendency toward galling was eliminated.

Fatigue failures can be minimized through careful inspection of equipment with particular attention to exposed threads or other conditions that might result in high stress concentration. I t is the author's opinion that some tool-joint failures s tar t from the inner surface of the joint as the result of fatigue accelerated by high stress concentration a t the root of a thread or a t some point of abrupt dimensional change.

In a recent paper dealing with the effect of grooves and fillets upon highly stressed automobile and truck axle shafts, Forrest F. Johnson1 described some interesting endurance tests made on several bars of S.A.E. 3140 steel, heat-treated to a hardness of 321 Brinell and "necked" in the center as shown in Fig. 10. The specimens were subjected to a sur- face stress of 77,000 lb. per sq. in., a t their minimum diameters on a rotating-beam fatigue-testing machine of the Farmer or Wohler type. The' following "life values" were obtained before failure of the respective specimens: - bar A, 81,000 revolu- tions; bar B, 75,400; bar C, 19,000; bar Dl 14,450; bar E, 13,530; bar F, 13,800; bar G, 12,650. These data show clearly the importance of stress distribu- tion with respect to endurance.

DRILL PIPE, CASING, AND OIL-WELL TUBING

Carbon and pearlitic manganese steels are used, almost entirely, for drill pipe. Although considera- ble study is being given to the effect of corrosion FIG. 9 . - F n ~ ~ HOLE

and hydrogen sulfide embrittlement upon the TOOL JOINT. ( C o w t e s ~ Reed Roller Bit Co.)

fatigue resistance of drill pipe, the scope of this paper will not permit a discussion of this complex subject here. I t is probable, however, that the excellent results obtained with alloy-steel sucker rods in certain troublesome wells may point the way out of this difficulty.

The development of low-cost corrosion-resistant materials for casing and tubing offers a fruitful field for metallurgical research. Steels

IF. F. Johnson: Effects of Groove and Fillet Shapes on Endurance ,of Heat- Treated Steel. Atdomotioe Industries (Sept. 22, 1934) 352-353.

10 PRESENT-DAY OIL-PRODUCTION EQUIPMENT

possessing satisfactory mechanical and corrosion-resistant properties, are not yet available a t a cost commensurate with the large ton- nage requirements.

FIG. 10.-SPECIMENS USED IN ENDURANCE TESTS. (Johnson: Aulomotive Ind.)

FIG. 11.-IDECO-UNITARY DRAW WORKS. (Courlesy Intwnalional Derrick & Equip ment Co.)

All cast parts of nickel-chromium steel, and brake bands:of high-carbon nickel- molybdenum steel.

Tremendous stresses are encountered by the gears of rotary machines, particularly in deep-well drilling.: Oil-quenched and tempered alloy steels are used extensively for these parts, although some manufacturers prefer the carburized steels. Properties of some typical steels used are shown in Table 1.

TABLE 2.-High-test Alloy Cast Iron TENBILE STRENGTH, 40,000 to 48,000 LB. PER.&. IN.

Column 1 1 1 2 1 3 1 . 4 ~ / , ~ 1 7 1 8 1 9 1 1 ~ 1 1 1 1 1 2

Section,in ................ Brinell hardness number. ..

Machinability.. .......... Wearresistance ........... Density ................... Total carbon. ............ Manganese ............... Phosphorusa.. ............ Bulfura. .................. Silicon.. ................. Nickel. .................. Chromium.. ..............

a Maximum. b Sound within section limits a t top of column. 0 Sound throughout widely varying sections.

1 t o 2 220

Good Very good

0.20 0.10

1.75 None

% t o 3 6 180

Readily

Good b

3.20-3.40

0.30 0.10

1.60-1.80 1.25

None

I t 0 2 260

Economi- cally

Excel- lent

0.20 0.10

1.75

4

% t o % 220

Good Very good

3.10-3.30

0.30 0.10

1.40-1.60 1.25 None

2 t o 4 180

Readily

Good b

2.90-3.102.80-3.002.90-3.102.80-3.002.70-2.90 0 .7M.950 .7M.950 .7M.950 .75-0 .950 .75-0 .95

0.20 0.12

1.00-1.200.90-1.100.90-1.100.80-1.000.704.90 1.25

% t o % 260

Economi- caUy

Excel- lent

3.00-3.20

0.30 0.10

1.20-1.40 2.00 None

2 t o 4 220

Good Very good

0.20 0.12

2.00 0.25-0.360.2M.350.35-0.450.50-0.60

% t o 1 180

Readily

Good b

3.10-3.30 0.55-0.750.5M.750.55-0.750.7M.950.7M.950.75-0.950.75-0.91

0.20 0.10

1.20-1.40 1.25

Ndne

2 t o 4 260 *

Economi- cally . @

Excel- lent

k 0.20 * 0.12

2.00

% t o 1 220

Good Very good

2.90-3.10

0.20 0.10

1.10-1.30 1 . 7 5 None

% t o 1 260

Economi- cally Excel- lent

2.80-3.00

0.20 0.10

1.00-1.20 1.75

0.25-0.35

I t 0 2 180

Readily

Good , b

3.00-3.21

0.20 0.10

1.00-1.21 1.25 None

Another important unit of a drilling rig is the draw works. These machines must often withstand very severe static and dynamic stresses, and therefore must be strongly built. Cast alloy steels are used exten- sively for sprockets, gears, drum heads, spools, clutch blocks, and other miscellaneous highly stressed parts. The following mechanical properties are typical of these steels in the normalized and drawn condition: yield point, 65,000 lb. per sq. in.; tensile strength, 100,000 lb. 'per sq. in.; elongation in 2 in., 20.0 per cent; reduction of area, 40.0 per cent; Izod ,impact test, 35 ft-lb. Fig. 11 shows a modern draw-works machine

F I G . 12.-GARDNER-DENVER STEAM PUMP OPERATING IN CALIFORNIA OIL FIELD.

equipped with a newly developed nickel-molybdenum steel brake band, possessing a tensile strength of approximately 200,000 lb. per sq. in. Brake bands made from this steel retain their shape during handling, and in service behave much like a spring in clearing the brake lining from the drum when the brake is released.

Crown and traveling blocks must be strongly built to withstand the severe loads imposed upon them during drilling. They are frequently subjected to severe shock or impact loads when pulling casing or when performing a fishing operation. Alloy-steel bearings and pins are used almost exclusively in the construction of this equipment. The sheaves and spacers, which are subjected to considerable abrasion by the wire rope, are generally cast from austenitic manganese steel. A recent trend in sheave development, however, is toward the use of medium carbon low- alloy cast steels, which can be readily machined to accurate dimensions

ALBERT G. ZIMA 13

and subsequently heat-treated to the degree of hardness best suited to the service conditions.

ALLOY CAST IRONS

The alloy cast irons form an important group of materials used in the construction of oil-production equipment. Low-alloy cast irons are used extensively by manufacturers of pumps, compressors, valves, oil and gas engines, etc., where readily machinable castings having high tensile properties are desired. The use of heat-treated, centrifugally cast cylinder liners for slush pumps and diesel engines made of alloy cast iron is now generally recognized as an economical and convenient means of improving the performance of this type of equipment. Fig. 12 shows a slush pump equipped with alloy cast-iron pistons, cylinder liners and valve platecovers. This iron, containing from 1.25 to 1.75 nickel and 0.30 to 0.40 chromium, can be machined readily to a fine smooth finish. The tensile strength is 45,000 lb. per sq. in., or more, and the castings are of uniform density and hardness throughout their heaviest sections. Cast iron of a similar type is also used extensively for pipe-line pump construction, for liners, heads, plungers, fluid bodies and fittings. Some manufacturers are now using alloy cast iron having tensile strengths greater than 50,000 to 60,000 lb. per sq. in., for high-pressure compressors, pumps, valves and fittings. The data contained in Table 2 are repre- sentative of average results obtained in commercial foundries with cast irons of the 40,000 to 50,000 lh. per sq. in. class.

Alloy cast irons are used extensively for the working barrels and plungers of oil-well pumps. These castings are usually rough-machined and heat-treated to a hardness of 500 to 550 Brinell, and subsequently ground to a smooth finish.

Among the highly alloyed cast irons, the austenitic type, containing 14.0 nickel, 6.0 copper and 2.0 to 3.0 chromium, is finding wide applica- tion for such parts as pump and valve bodies and trim in pipe-line equip- ment where resistance to corrosion is important. A modification of this material possessing a tensile strength range from 60,000 to 100,000 lb. per sq. in., with elongation in 2 in. of 8 to 25 per cent, is being developed for pipe-line flanges and bolts subjected to severe corrosion.

Modern oil-production practice offers to the engineer and metallurgist a wide field for research of a very fascinating nature. The design of new equipment and the selection and adaptation of materials of construction present some very interesting problems indeed. In the preparation of this paper some of these problems were mentioned briefly but with no attempt to discuss them in detail.

PRESENT-DAY OIL-PRODUCTION EQUIPMENT

The author acknowledges with grateful appreciation the assistance gi;en by the following persons in supplying data and illustrations in the preparation of this paper: C. E. Burt, chief engineer of Baker Oil Tools, Inc., Huntington Park, Calif.; Alfred C. Catland, engineer with the Globe Oil Tools Co., Los Nietos, Calif.; C. S. Crickmer, chief engineer of the Guiberson Corporation, Dallas, Tex.; R. L. Engstrom, chief engineer of the Hydril Company, Torrance, Calif.; H. W. Fletcher, chief engineer of the Hughes Tool Co., Houston, Tex.; Charles H. Shapiro, chief metal- lurgist of the Reed Roller Bit Co., Houston, Tex.; Dick Swinsky, Gulf Publishing Co., New York, N.Y.; H. P. Wickersham, chief engineer of the Baash-Ross Tool Co., Los Angeles, California.