Deepest Hole

With their newfangled electrical and seismographic prospecting instruments, petroleum geologists have found indications that oil formations may lie as deep as 25,000 ft. below the earth's surface. Until the visible supply of oil begins seriously to dwindle, probably no one will try to drill five miles. Meanwhile, in California's San Joaquin Valley, Continental Oil Co. has bored to 15,004 ft.--nearly three miles. This well, prosaically designated as K.C.L. A2, is the deepest hole ever made in the Earth. Having brought up oil from 13,100 ft., it is also the deepest producer.

Last week, K.C.L. A-2 was uneventfully running 400 bbl. of crude a day. It has been throttled down to that figure because of California's proration agreements. In a 24-hour free test run, it yielded 3,600 bbl. Even under prorated production, it is expected to return its investment--$305,000--in three years.

As FORTUNE pointed out last week in an article on K.C.L. A2, Continental's scientists and executives had no idea of making a record when the well was started. Encouraged by oil and gas strikes in a radius of 25 miles, they thought they would hit producing sand at 9,000 or 10,000 ft. They "spudded in" at midnight on June 21, 1937, using a 20-in. bit. In drilling for oil, the bit is carried on a shaft of hollow pipe, in 30-ft. lengths screwed together. A powerful steam engine on the surface spins the pipe and the bit. When a bit needs changing, all the pipe must be snaked out of the hole and then lowered again by the derrick. The pipe is kept full of mud to counteract the gas pressures below, which might otherwise blow out destructively at the top.

The first 500 ft. were like a "knife through cheese." There the driller switched to a 15 1/4-in. bit. At 9,500 ft., drilling speed had dropped to a foot an hour, and a new bit was needed every 25 ft. At 11,600 ft., the mud pressure was 9,000 lb. per sq. in. Apparently this huge force squeezed the water out of the mud into a porous sand formation at that depth, so that the mud caked and "froze" the bit collar. The drill pipe was fished out with difficulty but the collar was immovable. By means of a knuckle joint the frozen collar was sidestepped, and the hole, now pinched down to six inches, went on down. Near the bottom, the weight of the pipe was over a quarter of a million pounds. The temperature was nearly 270DEG F.

Superintendent Alexander Hamilton Bell will never forget the day the first oil spurted into the slush pits from the sand which had been tapped 13,000-odd ft. down. It was necessary to bail mud out of the pipe so that the gas pressure below could push up the oil. "We had swabbed 2,000 ft. of mud," said Superintendent Bell, "when suddenly the fluid rose 1,500 ft. in the hole. So we knew we had something. We swabbed a little more. Then it came naturally. For half an hour mud poured into the sumps, then turned to oil. I just stood there and looked at it."

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