| Thickness of Stratum | Total Thickness | |||
|---|---|---|---|---|
| Shale | 25 | feet | 25 | feet |
| Bastard Lime | 15 | “ | 40 | “ |
| Sand | 10 | “ | 50 | “ |
| Coal (No. 6) | 10 | “ | 60 | “ |
| White Slate | 65 | “ | 125 | “ |
| Sand | 15 | “ | 140 | “ |
| White Slate | 25 | “ | 165 | “ |
| Blue | 10 | “ | 175 | “ |
| Sand | 10 | “ | 185 | “ |
| Slate | 50 | “ | 235 | “ |
| Shale | 35 | “ | 270 | “ |
| Sand | 30 | “ | 300 | “ |
| Black Shale | 10 | “ | 310 | “ |
| Lime | 25 | “ | 335 | “ |
| Shale with Concretions | 100 | “ | 435 | “ |
| Slate | 25 | “ | 460 | “ |
| Limestone(?) | 30 | “ | 490 | “ |
| Shale | 35 | “ | 525 | “ |
| Salt Sand | 30 | “ | 555 | “ |
| White Slate | 100 | “ | 655 | “ |
| Slate and Concretions | 25 | “ | 680 | “ |
| Shale | 15 | “ | 695 | “ |
| Little Salt Sand | 20 | “ | 715 | “ |
| White Slate | 100 | “ | 815 | “ |
| Slate and Concretions | 100 | “ | 915 | “ |
| Brown Shale | 40 | “ | 955 | “ |
| Black Shale | 38 | “ | 993 | “ |
| Top Berea | 993 | “ | ||
| Bottom of Berea | 1008 | “ | ||
The depth of the well as shown by the steel line is 1012½ feet. It was drilled in the Fall of 1896, and was shot with twenty quarts of nitro-glycerine. It began flowing thirty barrels per day, but the production has diminished until at present it is producing only one barrel per day. Below the Berea the Bedford shales are found in their normal conditions.
The Oil Sand.—This is in all cases the Berea. The sand has the light gray color so common in this formation in other parts of the state. It is moderately fine grained, but there is considerable variation in this respect. Usually it is a pure quartz sand, but occasionally has thin layers of dark shaly material running through it. In thickness it shows considerable variation, but never disappears in this field. The normal thickness is usually given as twenty feet and the maximum reported is eighty feet. This depth was found on the Potts farm about one and one-fourth miles northeast of Corning, and on the O’Farrell farm about two miles east from the same town. In both cases a dark gray shale, probably the Ohio, lay below. The Bedford on this theory had been swept away before the Berea was deposited. In such abnormal depths the additions always appear to be on the bottom, showing that the surface of the underlying Bedford shale was quite uneven. Here, as elsewhere in the state, the drill shows the upper surface of the Berea to be uniform. It is worthy of note that the production of oil does not vary as the thickness of the sand. In fact in this field the great thicknesses are generally poor producers.
The “pay streak” or that containing the oil and gas ranges in thickness from 3 to 8 feet, but very few of the wells attain the maximum figure. Towards the margin of the productive field the “pay streak” thins, and finally disappears. The top of the “pay” usually lies from 10 to 15 feet below the surface of the Berea. As a rule the “pay” is coarser than other parts of the Berea, and generally the coarser the rock the larger the well. Sometimes in the thick part of the Berea there are two “pay streaks.”
The Wells.—The number of wells producing July 1, 1900, exceeded 600. About 100 dry holes have been drilled and about an equal number of wells have been abandoned, so that 800 is a fair approximation of the total number of wells drilled in the field. As a rule a well has been put down for each 8 to 10 acres of surface territory.
The wells have been cased through the salt sand, a depth of 555 feet in the valley at Corning. The casing has almost invariably been 5⅝ inches, inside measurement. The rocks comprising the underlying 160-180 feet, and terminating with the “Little Salt Sand” have furnished some water which has been disastrous to the wells. It reduced the gas pressure, thus necessitating pumping the wells earlier than otherwise would have been required, and perhaps prematurely destroying the life of the well. Had the wells been cased through the “Little Salt Sand” time and money would have been saved, and the production of the field would have been larger.
The western side of the field is quite free from salt water. It is on that side that the principal gas territory lies. On the eastern side of the field the conditions are more variable. In Trimble township, Athens county, the wells are free from water, while in Monroe township, Perry county, salt water is found in the northeast corner, and in Morgan county it is so abundant that operating is prevented. From this it appears that the western side of the Corning field is free from salt water, and that it is absent also on the eastern side at the southern margin of the territory, but that it increases rapidly to the northeast.
While the production of the wells after being shot has varied greatly, yet they have not furnished the great extremes that many other fields have. Few, if any of the wells, have started better than 125 barrels per day, and it has been estimated that the average for the entire field has been 20 barrels.
The wells have sufficient gas pressure to flow them during the earlier part of their lives, but later as the pressure diminishes they have to be pumped. Since the eastern side of the field has salt water the wells there have to be pumped earlier than those on the western side.
The Gas Wells.—The principal gas territory is that along Muddy Fork in Sections 22 and 29 Trimble township, Athens county, the best wells being found in the western half of the latter section on the lands of the Hocking Coal and Railroad company. The largest well in this field started at 3,000,000 cubic feet per day with a rock pressure of 400 pounds. It was drilled in the fall of 1897, and one year later was producing 2,000,000 cubic feet per day, and still another year later 1,500,000 cubic feet. Of the other wells in this territory two started at 2,000,000 feet each, two at 1,000,000 feet each, and three at 500,000 feet each. The decline in the smaller wells was not as rapid as in the larger ones since the demands made on them were not as heavy. Thus far no dry holes have been found in this territory. The reliance of the community is on this field where 5,000 acres are leased in one block.