( Think of it — orcr 2 million buyers paid $100 (cash) for this model No. 5 now OOWN offered Ulrcct-to-yuu at way below >ii original price — and on easiest teriiid beside":. Posillvely the greatest bargain ever offered. Aerept special 10 dav trial offtT and J»e eonvinrcd. See the nciit worlc it doe.-. — compare Us IjriKht, shiny looks uitliout risk. Lowest Price— Easiest Terms Ever Offered— Only 10c a day UoreisposftlvHy thechanr<>of« llfotimeto own a World-famous Stand- «rd UnderwiHxl No. 5 comi>li<to1y rffitiirihiMt like n*'WBtth*i very low**Pt pricB and easiest ti^rms. All ci>m[tlt^tc with nHKli-m improvemfntji In- cludhiBstandard4-piw key lM>ard, bark Hpai'tT. automatic ribbon ri-vrtrs>o ■htft look. 2-color ribbon, I'tc.ldtMil for busiiifsriaiui profeaHional riifii- teachers, atudunU, story wHtcts. etc. Uoirtli-l this chance Dass by. 10 Day Trial Yoa save over S«><J by quick action. These Ken uineiniaran teed underwoodA now only (39.90 leash) while limited supply la«tji. Only $1 down brintf* the Underwood for 10 daya' trial. If you kei'p it — only 10c a da>- »oon pay s for your Underwood on our now low prici- and eaKivHt terms. Send at once b>>- fore this Hpecjal offer la withdrawn. Remember every machine fully guar- anteed and Kent on 10 day trial. FREE! Money-Makins Opportunity Learn touch Ivpewrlt- intc free] Complete (home study) course of famoa-4 Van Sant Svs' tenn ^iven with tills offer. Fully illustrated — easily learned. {"international TYPEWRITER EXCHANGe"! I 231 West Monroe St.. Chlcafto. HI. Dept. 1207 ■ I 1 enclose $1 dep.>!*it. Send Und.TW(«Ki No. 6 ^F.O.B. Chfcaifu) at once for 10 dayn' trial. If I am not perfectly Katisfied lean r»- I I turn it express collect and uet my deposit back. If 1 keep It I will ■ pay S3 a month until 1 have paid $44.^*0 'term price) In full. ■ Name Aite. • I I Addrx. I I I I Town.. ^ Want a Steady ^ ■ Government Job? New Bandit Proof Railway Mail Car Railway Postal Clerk $1900 to $2700 a Year Franiilin Institute Dept. J-279. Rochester, N. Y. Muy Other Govemnwnl Jobs MEN— BOYS 18 to 50 Paid Vacations / Common Education Usually Sufficient / i. i . -.u . ttenllemen: Ilu^h to me without What you do with v* charBe 32-paBe ImwIc with UX of lh« coupon J ■.^■.r'""'iTr"^ """^ position. ■1^ ohiHinahle. Advise inc reKardinc the means more to ^ you than to ^ salaries anyon* C •IM. / hnur». duties, vaeatinn and full lit. / Name,. y Address.. DEEPEST OIL WELL TWO MILES DOWN (Continued from page 135) teeth which bites out circular sections of rock much as a coolcie cutter cuts circles of dough, brings to the surface cylindrical cores which are cross sections of the strata pene- trated. Correlating the data gained from the cores of a number of wells in one field, geologists now plot maps of the subterranean structures with surprising accuracy. Ever a relentless enemy of producing oil wells, intruding water, flowing around the casing into petroleum sands and forming an emulsion ruinous to the quality of the oil, had brought many a fine w'ell to an early end. Drillers sought to shut out this water by ending the casing in a tapered joint which they drove as tightly as possible into a solid formation, sealing the pipe against water from higher strata. Where the hole ter- minated in a soft formation, a sack of flax- seed was sometimes dropped to the bottom, where it swelled and forced itself up around the casing, shutting off the w'ater to a certain extent. Lead shavings, clay, wheat, chopped rope, and many other substances were used for this purpose, but with poor success. R. W. Stephens, experimenting on a Union Oil Company well in the Purisima field, hit upon an improved method. Dumping liquid cement to the bottom of the hole to a depth of twenty-six feet, he lowered the ten-inch casing into this plastic mixture. When the cement had set thoroughly, the hole was drilled through this plug to the oil sand. The water shut-off was perfect. LVTER, oil men learned to place a packer
- at the bottom and drive in the cement
by compressed air, allowing it to harden under pressure to form a solid, dry joint. Today, clean holes sealed perfectly against intrusive waters permit the flow of oil and gas until the supply is completely exhausted. Other inventions have since come rapidly to the aid of the oil man. From the terrific heat of the electric blast furnace have come Borium, Blackor, and Diamonette, materials so hard they easily cut glass. Used for facing the cutting surfaces of drills, they outwear the hardest of steels and vastly reduce the amount of time lost in changing bits. Drills tipped with disks that cut at an angle now sharpen themselves as they turn, keeping a razor-sharp edge at all times. For rock work there are bits whose cutting sufaces are toothed cones, which mill around as the drill rotates and literally pulverize the rock into dust. Streams of salt water, leaking into oil strata, now betray their deadly presence to the "water witch," a queer instrument based upon the principle that salt water is a far better conductor of electricity than pure water. Dropped into the hole, which has just been washed clean with fresh water, this "water witch" gives a deflection upon a meter when a zone of the conducting salt water has been reached. HOW straight is an oil well? A few years ago, oil men didn't know. An early sur- vey indicated a drift in one well of 1,2CXD feet from the vertical. Drillers scoffed at the crazy instrument that had measured the hole, untii, one bright morning, two wells located SOO feet apart at the surface came together. Operators began to take notice. Later, the discovery of oil at Signal Hill, just at the edge of the city of Long Beach, Calif., brought such a multitude of derricks that often adjacent rigs were so close one could not walk between them. It became a common thing for a driller to find he had penetrated the casing of a neighbor. . othcr serious problem is the maintain- ing of the circulation of the steady flowing mud stream. When it ceases, trouble begins. Underground caverns sometimes cause grave difficulties by swallowing the down-flowing stream of mud, instead of returning it to the surface. One remarkable well — the No. 1 Crowell at Tulsa, Okla. — ran into a cave that devoured 4,400 sacks of cement without a murmur. Nine hundred barrels of lime were dumped in — and the hungry well asked for more. Next came 300 wagon-loads of red clay, but they didn't faze the well. Desperate, drillers sent out an SOS to the farmers in the vicinity. They brought 500 bushels of oats, 180 bush- els of corn, twenty tons of cottonseed hulls, and 180 bushels of bran. When an additional twenty tons of ensilage had vanished into the well, the drillers gave up in disgust and abandoned the hole. Trying it again about a quarter of a mfle to the south, they struck the same formation — evidently an underground cave of enor- mous size. Here they succeeded in reaming and setting pipe though the cavern, which logged 130 feet from top to bottom. SETTING the casing in deep wells is no mean mechanical problem. Lowering a pipe weighing hundreds of thousands of pounds to a predetermined point that must be located within a few feet or even a few inches in nine or ten thousand feet, drillers must "land" the casing in a solid formation that holds the cement firmly. Inside the casing itself hangs the tubing through which the oil flows. The w-eight of this long string of pipe is sometimes too great for its .strength, and the tubing snaps, letting the lower portion plunge downward. A clever mechanical device is now attached somewhere upon the lower portion of the tubing. If the pipe gives way, its downward plunge is halted within five inches by viselike spring teeth that bite into the surrounding casing, checking the fall. Fishing tools snag the broken section, and the spring teeth yield to an upward pull, allowing the tubing to be withdrawn for repair. One remarkable clever instrument was devised by an engineer who knew little about oil drilling, but much about engineering. Some one explained to him the need for a steady combination of speed and pressure on the revolving drill. "I can make a gadget that will regulate that automatically," he said. True to his promise, he invented the "Drill- ometer," a device much Hke the differential of an automobile. One end of the "differ- ential" is attached to the speed regulator, another to the engine that hoists the drill up and down. If the drill strikes a soft formation and begins to speed up, it is lowered and more weight is applied. If a snag is struck, the slowing of the drill lifts the weight from it. Simple, but effective. DEEP drilling opens new possibilities to lure the oil man, for beneath old zones that have yielded fortunes may lie nfw pools of untold richness. One morning in June, 1929, drillers were lamenting a "twist- off" in Associated's Clarke No. 2, a former producer that was being deepened to explore new depths. Fishing with strange hooked tools, they sought to recover the lost drill stem, which filled the hole to within forty feet of the bottom. Suddenly a column of oil, bursting from the well, shot up to the derrick top. It was the first indication of the amazing Lower Clarke zone, last and deepest of the prolific Santa Fe Springs strata, which caused that field's production to jump from 16,000,000 barrels in 1928 to 76,447,464 barrels in 1929. 136 POPULAR SCIENCE MONTHLY
