|The system of boring is percussive|
|The deepest actual boring, 1,160 meters|
|Fou Chouen, where natural gas wells are principally found,|
CHINA MINERAL RESOURCES OF THE UNITEDSTATES 1891
Annales des Mines, vol. xix, 1891, describes in detail the brine and gas wells of the province of Sze Chuen, in western China. This produces annually, as nearly as can be estimated, there being no regular statistics, about 812,000 tons of salt, which is entirely derived from borings, the salt being accompanied in places by petroleum and natural gas, the latter being utilized for boiling down the brine. The most important centers of production are in a district about 80 square miles in extent, about 25 miles northwest of the town of Fou Chonen. The geological structure of the district appears to be somewhat complicated, but, according to the author, a complete succession from Cambrian up to Tertiary and post-Tertiary strata, which is recognizable in the following order:
Stratigraphy of the Sze Chizen gas fields, China. Meters.
Yellow sandstone Tertiary 38 to 100
Gray limestone------------------------------------------------------- 200
Ferruginous oolite, often with bituminous springs at
Blue and yellow sandstone, Lias 270
At this level gas is found sometimes in small quantities.
Bluish gray marl 330 to 600
White limestone, Permian
These strata yield brine of a yellowish color and medium saturation (10 to 15 % of salt)
Sandstone and limestone with coal Carboniferous.
Brown shining shale Silurian.
Green schist Roofing slates.
Dark colored brine, of the higher strength of 15 to 28 percent of salt, is found below the last mentioned strata at depths varying from 930 meters to 1,100 meters, as well as the most important gas springs. As a rule, the upper yellow brine bearing beds are not found in these deep borings.
system of boring is percussive, the cutting tool
piece weighing from 200 pounds to 300 pounds, being suspended by a
and lifted about 2 feet at a stroke, by a lever worked by groups of
acting as dead weight. According to the depth, from two to eight
men are required to lift the tool from twelve to fifteen times a
the gangs being relieved at intervals of ten minutes. The cutting tool
has eight steel-faced teeth, but without grooves, so that the, detritus
accumulates at the bottom of the hole. This is removed by a sludger,
of a cylinder of wood covered with deep notches arranged ladder wise,
is lowered into the hole and moved about by a jerking motion on the
until the grooves are filled with the sludge.
As may be imagined, the progress of the work is very slow, varying from a few feet per day in loose ground to an inch or less on very hard rock.
Some of the deeper wells have taken from twenty to forty years in sinking, and have ruined several sets of adventurers in succession.
actual boring, 1,160 meters, has never yielded anything.
The accidents to which the borings are liable and the method of remedying them are treated at length by the author, with illustrations of the tools employed from Chinese drawings. These are generally similar to those adopted in Europe; but the construction is very different in principle, bamboo and string entering very largely into their composition instead of metal.
As a last resource, the method of pulverizing a lost tool is adopted and carried out with incredible patience. The removal of a tool weighing 300 pounds, in this manner, required about five years continuous work, night and day, of thirty-two men, at a cost of about Y, 3,000.
The brine is brought to the
surface by tubular buckets of bamboo, with
a foot valve varying from 2 to 6 inches inside diameter, and from t6 to
140 feet in length.
The bucket is lowered and lifted by a flat rope 20 millimeters and 5 millimeters thick, formed of slips of bamboo united by hempen cords winding upon a gin which is usually drawn by buffaloes, two, four, or six of these being required, according to the depth of the well; but in the shallower ones the lifting is sometimes done by a windlass worked by from two to six men treading fashion. The load upon the rope in the deeper wells in some cases exceeds 30 hundred weight, corresponding to a stress of 9 1/2 tons per square inch.
The quantity of brine raised at each lift varies from 116 liters (250 1/2 gallons) with the smallest bamboos, to between 620 and 950 liters (136 to 200 gallous) with the larger ones, and under the most favorable conditions from two to four lifts may be made per hoar, according to the depth. When the bamboo is raised to the surface, a cover is pushed over the top of the bore hole, the valve is lifted by the ladder with an iron hook, and the brine runs into a reservoir.
The product of the deep wells is very dark-colored, and often emits suphuretted hydrogen in sufficient quantity to be dangerous to the workmen about the top of the pits if it is incautiously inhaled. In addition to salt, some of the wells yield petroleum and gas in variable quantity; the former is skimmed off from the surface of the water after it has been allowed to settle in the reservoirs.
The product varies in quality from a pure white-burning oil to yellow, greenish, and black kinds of low illuminating power and giving much smoke. All are, however, burned, as the Chinese have no knowledge of petroleum refining.
The wells being generally
away from the salt works, the brine is carried
to the latter either by hand, when the journey is short, or by conduits
made of bamboos, with chain and bucket-lifting wheels for overcoming
differences of level, when a greater distance has to be traversed.
the district of Fou Chouen, where natural gas
wells are principally found, from 600 to 1,200 pans may be heated by a
single well. The principal supply is obtained from depths of not less
670 meters. It is manly marsh gas, being less carburized than that
at shallower levels, which burns with a tolerably white flame, but is
got in small quantities.
The whole arrangement is very primitive and imperfect, nothing of the nature of a stop valve being displayed anywhere on the line of pipes. When the workman wishes to extinguish the flames, he places a brick on the top of the burner; but the gas continues to flow without interruption, and disperses in the atmosphere. As, however, the work is done under open sheds, there is not much danger of explosions; but the smell of the gas is very prejudicial to the health of the workmen.
The saltpans are presently
built by the proprietors of the gas wells,
who leases them to salt makers at a rental of about Y(L?) 32 per
The yield to the proprietors is therefore large, but the duration of
gas is very uncertain.