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Drillers In Doublets

Written by Iver P. Cooper

I don't want to be critical of coal mining, especially not where Mike Stearns can hear me. But the fact remains that coal has some serious disadvantages, both as a fossil fuel and as a source of organic chemicals.

Extracting coal is labor-intensive; you have to dig shafts and tunnels, keep the works from flooding, and provide ventilation. It is also dangerous: the roof can collapse; methane gas in the mine can explode; and breathing of coal dust leads to "black lung." Once the coal is on the surface, it must be transported by trains or vessels.

If the coal has a high sulfur content, then the sulfur must be removed. Otherwise, burning the coal will result in the emission of sulfur oxides, and the formation of acid rain.

To obtain chemicals from coal, the coal is cooked and fractionated. This is a batch process; the coal is loaded into iron vessels with small vents. Hydrocarbon gases escape from the openings; the solid material which remains is coke. When the gases are cooled, some of the hydrocarbon will precipitate as coal tar. The remainder is subjected to fractional distillation and other processes, yielding ammonia, light oils, and "coal gas." You get only eight to ten gallons of coal tar from one ton of coal.

Because of the difficulties in handling solid coal, chemical engineers have developed techniques for converting it into a gas or liquid. Of course, these increase production costs.

Hence, this essay will examine the extent to which the United States of Europe (USE) might be able to exploit natural gas and petroleum.

Natural gas is mostly methane, with small amounts of ethane, propane, butane, isobutane and pentanes. These are all small linear hydrocarbons, and they are useful in the chemical industry. Still, I expect that the principal use of natural gas (especially the propane fraction) in the USE will be to keep gas-guzzling twentieth-century vehicles running.

We will want to obtain our aromatic hydrocarbons, such as benzene, from either coal or petroleum. Benzene is a trace ingredient (only about 0.06 - 0.29%) of coal tar, itself a minor product (in a quantitative sense) of coke production. Until World War II, benzene was nonetheless obtained from coal tar; afterward, to feed the growing plastics industry, it was produced from petroleum. Petroleum typically is around 3% benzene. Plainly, petroleum is the richer source.

What are the other advantages of petroleum? When you drill for it, there is no need to send anyone underground. Once the drill reaches the oil reservoir, the oil is driven to the surface by the action of an overlying "gas cap," gases dissolved in the oil, underlying water, or, on rare occasions, gravity. Indeed, in some cases, the escape is overly vigorous; the oil gushes out and the well must be brought under control so that it is not wasted.

Transportation costs are much less than they would be with coal, at least once oil pipelines can be constructed and protected. Finally, since oil is a fluid, it is easier to refine into its component hydrocarbons. For example, the refining can be conducted as a continuous process. (Natural gas has similar advantages over coal, at least if you can carry it in pipelines.)

Local Resources

Fictional Grantville is based on historical Mannington, West Virginia, with one very important exception: it does not have Mannington's oil wells, or any of its drilling rigs. (It is unclear whether the oil wells just ran dry or never existed. If they merely ran dry, then there might be pumping equipment, casing and pipeline available for salvage.)

Fortunately, Mannington's natural gas wells have been bequeathed to Grantville, and we know that they are still productive. In 1633, Chapter 34, Mike says, "we're getting a fair amount of oil now from the gas wells right here in Grantville, too, since we upgraded them." And in Loren Jones' "Anna's Story," from Grantville Gazette Number One, we are told, "like many of his neighbors, George ran his stove, water heater, dryer and furnace on gas from under his own land. The wellhead and compressor were out in the barn."

The Grantville (Mannington) public library owns a number of possibly useful accounts of the oil industry (see Appendix). There should also be some local knowledge independent of the library's resources. West Virginia has produced oil since 1859; it produced 16 million barrels in 1900. It was the leading natural gas producing state from 1906 to 1917. It is not unreasonable to suppose that pre-ROF Grantville high school students made field trips to the Oil and Gas Museum in Parkersburg, West Virginia. And perhaps they had to write research essays

afterward . . . which are still in a box at the school somewhere.

Some displaced up-timers may have worked in the oil or natural gas business. We know from 1632, Chapter 8, that some residents have at least participated in the West Virginia Oil and Gas Festival; that is how they know how to build steam engines. Perhaps one of them has a copy of a vintage Oil Well Supply Company catalog; these have impressively detailed drawings of drilling equipment, parts lists, and so forth.

In 1633, Chapter 3, we are told, "downtown Grantville had some large and multi-story buildings left over from its salad days as a center of the gas and coal industry." So there might be some interesting artifacts in cellars or attics, or perhaps some resident has a little collection of souvenirs, collected when his grandpappy worked on a derrick.

Another point to keep in mind is that many of the techniques and much of the equipment used in oil and gas drilling are also used in drilling for water (or brine). According to the West Virginia Department of Natural Resources, a Mannington resident, Luther Dell Michael of Luke's Drilling, is certified to drill water wells within the state. Perhaps he has a Grantville counterpart; if not, there should be some residents with water well drilling experience and perhaps even a light drilling rig.

Also, drilling is performed in the coal mining industry: to find an underground coal seam, to start a shaft, or to vent methane out of the works. Chances are that there are UMWA members who know something about drilling, and there may even be drilling equipment.

Down-timer Knowledge of Petroleum

In the ancient world, both bitumen (tar, asphalt) deposits and liquid oil seeps were observed. The tar was used as a binder (e.g., to mortar bricks together) and as a waterproofing agent (especially as caulking for ships). The liquid oil served as a medicine. Both were used as a fuel (e.g., in Persian fire worship) and as incendiary agents in warfare (notably the "Greek Fire" of Byzantium). While these ancient exploits were probably forgotten by the seventeenth-century Europeans, these are uses which I would expect to be rediscovered, time and again, whenever a curious passerby happened upon a lump of asphalt. Thus, there would be some local knowledge of petroleum wherever there were oil seeps.

Moreover, I would think that the peculiarities of petroleum, in particular the fact that it was a liquid that could catch fire, would cause it to be remarked upon to strangers, resulting in the dissemination of information about it.

According to Dr. E.N. Tiratsoo, "samples of petroleum oils were brought back to Europe by travelers from Baku, Burma and China" (Tiratsoo, 2).

Marco Polo visited the ancient Baku oil fields in 1250. He reported that "a hundred shiploads might be taken from it at one time" (James and Thorpe, 405). It was apparently used at that time both as a fuel, and as a veterinary ointment (for camels with mange).

There is also ample evidence of pre-Ring of Fire (ROF) knowledge of European oil seeps. The best known were those at Wietze (Hannover, Germany), Pechelbron (Alsace), Beziers (southern France), Agrigentum (Sicily), Modena (Po valley, Italy), and Tegernsee (southern Bavaria), and at various locations in Galicia and Romania. (HBS 2). The oil of Tegernsee was sold for medicinal purposes as "Saint Quirinus Oil" as early as 1436. The Alsatian oil was discovered in 1498, and the Galician "earth balsam" in 1506. The petroleum of Agrigentum was first mentioned by ancient Roman writers. Salsomaggiore in northern Italy had gas springs, which is why, in 1226, it adopted a salamander surrounded in flames (i.e., a fire elemental) as its municipal emblem.

There was a small scale local trade in European oil before the Ring of Fire. Moreover, if there were a sudden increase in the demand for oil, the down-time Europeans would look further afield, and they, or their trade contacts in the Ottoman Empire, would probably be aware of the Near Eastern seepages in Baku, Ecbatana (Kirkuk), Ardericca (near Babylon), Zacynthus (Zante), and Tuttul (Hit). Spanish and English mariners visited the Trinidad pitch lake in the sixteenth century, and Joseph de la Roche d'Allion commented on the oil springs of New York in Sagards Histoire du Canada (1632). The Spanish were probably aware, by 1632, of at least some of the oil seepages of Cuba, Mexico, Bolivia and Peru. (1911EB).

The German Oil Fields

We first heard of the Wietze oil field, near the town of Celle, in 1633, at Jesse Wood's press conference. The extraction and refining operation is being supervised by Quentin Underwood, the secretary of the interior and would-be oil tycoon. Most of the financing is coming from unidentified Germans. It appears that the refined oil will be transported by river, specifically, by barges towed by the steam-powered tugs Meteor and Metacomet. The field lies within the province ruled by George, the duke of Calenburg, and he is already enjoying economic fringe benefits; the Abrabanels are opening a bank branch in the provincial capital, Hannover.

The 1911 Encyclopedia Britannica notes that Hannover has oil production from Pliocene, Cretaceous, Jurassic, Triassic and Devonian rocks. The Wietze field is famous in geological circles because half the total production comes from mining rather than drilling. This implies that some of the oil is quite close to the surface. Still, that doesn't guarantee that all drilling will be successful. In 1857-1863, Professor Hanaus of Hannover bored ten wells in its vicinity, but only three showed even traces of oil (HBS 4).

This field is one of a cluster of a score of small oil fields, which mostly lie on or southwest of a line running from Bremen to Magdeburg. The largest of the lot is Nienhagen, which produced 2,200,000 barrels of oil in 1940.

However, the most prolific oil field in all of Germany is the Reitbrook field, near Hamburg, which yielded over 2,500,000 barrels the same year. There are 1,000 acres of producing field, and they lie atop a salt dome (see below). If you drill in the right place, you will find a gas sand about 300 feet down, and below it, at 700-800 feet, the oil horizon, made of fissured Upper Cretaceous chalk. (If you hit salt, you know you are out of luck.) It will probably be discovered only once geologists thoroughly map 163x Germany; in our time line, the field was discovered in 1937. (Near Reitbrook we may find two more fields, Sottorf and Meckelfeld.)

North of the mouth of the Elbe, near Meldorf, are a few more small fields. They, too, are salt dome-associated. Oil from Reitbrook or Meldorf could be transported by barge on the rivers Elbe and Saale.

Borings in a potash mine resulted in the chance discovery of oil in Thuringia, specifically, at Volkenroda near (and northeast of) Mulhausen. That is less than 60 miles from Grantville.

Also worthy of note are the Bavarian oil seepages (near Tegernsee, home of the relics of St. Quirinus), and the small oil fields near Bruchsall and Heidelberg, opposite Pechelbronn in France. (See generally Tiratsoo,126-31.) Bruchsall and Heidelberg are south of Mannheim and east of the Rhine.

Only the Wietze and Tegernsee fields, and possibly the Mannheim fields, are likely to be known to down-timers (by "known," I mean, they know of the associated seepages). The other German fields must be located by prospecting. In some instances the field of search can be narrowed down by reference to up-timer geographic texts, such as the Hammon Citation World Atlas. This shows that modern Germany has seven oil sites and five natural gas sources. Comparing this map to Tiratsoo's 1949 map of German oil fields, it appears that the atlas will guide the USE to the fields at Meldorf, Reitbrook, and Nienhagen. It also shows three fields that Tiratsoo either ignored or didn't know about. These are southwest of Bremen, west-northwest of Osnabruck, and south of Frankfurt.

Other European Oil (and Natural Gas) Fields

Discounting the North Sea, Europe is not a major producer of oil. The most productive portion is in the foothills of the Carpathian Mountains, especially in Galicia and Romania.

In the seventeenth century, Galicia (now the western "spur" of Ukraine) was part of Poland. There is some question as to how welcome USE entrepreneurs will be in Galicia, as Sweden and Poland were at war as recently as 1629 (Sigismund thought he was the rightful king of Sweden.)

The main Galician oil field is Boryslaw (over the period 1855-1949, it produced 180 million barrels), followed by nearby Schodnica-Urycz (with oil reserves about one-seventh those of Boryslaw).

Perhaps sixty miles west-northwest of Boryslaw, inside modern Poland, there is the small Gorlice-Sanok area. This includes Bobrka, which has an oil history museum. According to their website, the first Polish mention of oil was by Jan Dlugosz (1415-1480). In the seventeen century, they add, rock oil was found near Drohobycz and Krosno (west-northwest of Sanok).

Getting this Galician oil to Grantville or Stockholm would be rather arduous. Initially, the Krosno and Sanok oil would probably be transported down the San and Vistula to the Baltic Sea. The petroleum of Boryslav might need to ride the Dniester to the Black Sea, and then come around the long way through the Mediterranean Sea and the Atlantic Ocean.

The Romanian oil, in a geographic sense, is more accessible; oil from the many fields within a forty kilometer radius of Ploiesti can be hauled to the Danube and then shipped upstream (to Vienna) or downstream to the Black Sea. Unfortunately, this is Ottoman territory, and therefore hostile to uptimers.

Cardinal Richelieu is likely to make a grab for the small Alsatian oil field at Pechelbronn, discovered in 1498. (Historically, Alsace was not absorbed by France until 1639.) The oil is found in sand lenses. Of the oil here, about 43% can be removed by mining, and another 17% by drilling (the rest is considered unrecoverable). From 1745 to 1849, twelve wells were drilled or dug, to depths of thirty-one to seventy-two meters. Average production in the late Forties was about 500,000 barrels, and total production over the last 150 years has been about 3,000,000 metric tons.

The Italian oil fields are small, and thus it is likely that the only ones which will be exploited in the near future are the ones which are known to down-timers as a result of seepages, or through pirated copies of the Hammond Atlas. The latter only shows two oil sources, one near Ragusa in Sicily and the other in the Po river valley, to the northwest of the gas seeps of Salsomaggiore. The development of these sources are best considered as possible joint venture projects with our colleagues in the Most Serene Republic.

A very large natural gas field lies close at hand, in the northwestern province (Groningen) of the United Provinces of the Netherlands, and is still under Dutch control. This territory might well be subject to protective occupation by USE military forces, if that were considered desirable. Would-be natural gas tycoons would be well advised to read the "Fuels" essay in the Grantville Public Library copy of Encyclopedia Brittanica before they set out. This reveals that the Groningen field is large (24 kilometers wide by 40 kilometers deep), but the productive formation, a Permian sandstone, is deep (pay depth is 3,440 to 3,050 meters). That means it is not a good target for neophyte drillers.

Oil Fields Outside Europe

One advantage that the transplanted West Virginians have over main timeline wildcatters is that they know in advance which parts of the world to start looking in.

Standard encyclopedias will tell them about the world's major oil fields. Unfortunately, they are all outside USE territory. Some might be developed as joint ventures with the Venetians or the Dutch.

As long as the Ottoman Empire remains hostile to Grantville, it will be difficult to directly exploit any of the oil fields in the Persian Gulf states (modern Iran, Iraq, Saudi Arabia, Kuwait, Bahrain, Qatar), in the Baku region on the west coast of the Caspian Sea, or in Libya. While some of the fields are controlled by the Persians, rather than by the Ottomans, the most direct shipping routes would still pass through the Sultan's domains.

But what we can't drill for ourselves, we can still buy. Muslims began commercial production of oil at a very early date. Baku oil was being sold as early as 885 AD, and crude oil was also produced commercially, pre-ROF, from seepages on the eastern bank of the Tigris, from the Sinai in Egypt, and from Kuzistan in Persia. (The wells were dug, not drilled.) Islamic alchemists were also able to fractionate naphtha by distillation. Hence, the USE could at least import petroleum, crude or partially refined, from the Ottoman Empire.

There are several noteworthy oil fields in Latin America, notably on Trinidad, and in Venezuela and Mexico. My initial concern was that this was within the Spanish sphere of influence. However, the island was only sparsely populated, and the natives were hostile to the Spanish. So a strong enough party of adventurers could certainly take over. In 1595, Raleigh made a surprise attack, with 100 to 200 men, and slaughtered the Spanish settlement. However, Raleigh was not interested in colonizing Trinidad himself, just in using it as a springboard for an expedition into Guyana (the fabled location of El Dorado).

Europeans first learned of Trinidad's oil in 1510, when Columbus shipped samples back to Spain. Prior to European settlement, Indians used Trinidad's asphalt to caulk dugout canoes, so Sir Walter Raleigh, who used it to repair his ships on his 1595 visit, was just copying native practice.

The Pitch Lake, now a tourist attraction, is large (95 acres), and 300 feet deep at the center. The asphalt can be broken out by picks; there is no need to drill.

Of course, there are other, less immediately accessible, sources of oil on the island. Even there, it should not be necessary to drill to great depths to obtain petroleum. In 1857, the Merrimac Company drilled a well to a depth of 280 feet, and struck oil. In 1867, Mr. Walter Darwent found oil on the Aripero estate at a depth of 160 feet. And the next year, the Trinidad Lake Petroleum Company was gratified by the discovery of oil at La Brea at a depth of 250 feet.

In 1902, a well was drilled to 1,015 feet in three months using the "Canadian Pole method of percussion drilling." It produced a small gusher (100 barrels a day).

The first big find was in 1911-12; one well yielded 10,000 barrels per day from a depth of 1,400 feet.

The Trinidadian reservoirs, when intact, have a high gas pressure. That is both good news (initial production can be high) and bad news (the well may blow wild, wasting oil and blasting casing, tools and rocks into the air). It became customary to keep an emergency crew on hand, armed with pumps, shovels and picks.

Venezuela also has a great deal of oil; in 1996 it ranked sixth worldwide in proven oil reserves. Its oil is already known to down-timers; "the first oil exported from Venezuela (in 1539) was intended as a gout treatment for the Holy Roman Emperor Charles." At Guanoco you can find the Bermudez Asphalt Lake, covering 1,100 acres with an average depth of six feet.

In what would have become the United States, were it not for the Ring of Fire, oil and natural gas can be found in the Appalachian mountains (Pennsylvania and West Virginia), in the midcontinent region (Louisiana, Arkansas, Mississippi, Oklahoma, Kansas and Texas), in the Rocky mountains (Colorado and Wyoming), in California, and in Alaska. (There is also oil in Alberta, Canada.)

In our own timeline, beginning in 1638, the New Sweden Company established colonies in modern Delaware, New Jersey, Pennsylvania and Maryland. It is possible that a similar venture in the 163x timeline could exploit the petroleum of Pennsylvania and West Virginia, but it is doubtful that it would be economical for them to ship it back to USE. Still, an advantage of an American expedition is that the Grantville Public Library is likely to have specific information (e.g., where and how deep to drill) only about American (especially West Virginia, Pennsylvania and Ohio) oil fields.

Nigeria is also a major oil country (in 1995 it ranked twelfth in proven reserves). In 1632, it was not dominated by any European power, and it is convenient from a transportation standpoint; oil could be shipped by sea all the way from Nigeria to Germany. This isn't as cheap on a per mile basis as pumping it through a pipeline, but it is certainly superior to transporting it by rail from Baku or Ploiesti.

However, an expedition to Nigeria is not for the faint-hearted. The Encyclopedia Americana will tell Grantville residents (and spies) to look for oil in the Niger river delta (first discovered there in the Fifties). What they won't know, until they get there, is that the oil fields are in swampland, and that they will probably need to drill from barges.

Where Is Oil Found?

Oil is a liquid rock. In fact, another name for oil—petroleum—means "rock oil." Oil is formed primarily from marine sediments rich in organic matter (bacterial, plant, and animal remains). These deposits are usually found along the rims of ancient ocean basins, where sea life was most abundant. In these basins, as more and more sediment was deposited, the layers below were compacted, becoming rock. The compaction also resulted in physical and chemical changes in the organic matter, eventually resulting in the formation of oil in the pores of this source rock. Further compaction drove the oil out.

The first criterion for the formation of a useable oil pool is that the oil find its way into a suitable reservoir rock. This must be porous (so it can hold the oil) and permeable (the pore are interconnected, so oil can flow into and out of it). Think of the rock as being like a can filled with marbles. The usual reservoir rocks are sandstones and limestones.

Since oil is lighter than water, it constantly tries to migrate upward and outward. If it not somehow trapped, it will pass out of the reservoir rock, eventually reaching the surface, evaporating, and becoming lost to the atmosphere. Thus, to have a viable oil reservoir, it is therefore not enough to have a good reservoir rock; one must have an oil "trap."

The trap is formed of a rock which is relatively impermeable to oil. This is sometimes called the cap rock. Shales make excellent cap rocks. Of course, to form a trap, the cap rocks must be positioned to prevent the upward and horizontal movement of the oil in the reservoir rock. This kind of positioning can occur as a result of the folding or faulting of the earth's crust.

The same structures which trap oil can also trap gas, and the same field can produce both fossil fuels.

Prospecting for Oil

Even if you know that there is oil in, say, Saudi Arabia, you still have to find it. In searching for oil you must strike a balance between trying to cover a large area and not overlooking any indications that oil might be present.

The simplest approach is that you walk over the land, looking for surface signs of oil or gas. A more sophisticated prospector will make an effort to deduce the subsurface structures by finding places where the underlying rock layers are exposed, such as outcrops, roadcuts, ditches, wells, and mines. By comparing the rock beds at different sites, you build up a picture of how the underlying rock layers are contorted. With enough information, you can identify a potential oil trap. Finally, you can also use geophysical methods to find out what is below the surface. These prospecting methods are discussed in greater detail below.

Oil Signs

Early prospectors combed the land for signs of oil, such as oil and gas seeps, mud volcanoes, solid petroleum deposits, burnt clays, and "showings" of oil in water and salt wells. They then drilled nearby.

An oil seep or "spring" is a place where oil seeps to the surface. The La Brea Tar Pits in Los Angeles are a good example. The oil may reach the surface in a number of ways. The trap may be eroded to the point at which the reservoir surface "outcrops," that is, is exposed to the surface. Or the oil in a trap may be tapped by a joint (a crack) or a fault in the overlying rock. Either way, the oil reaches the surface and slowly evaporates. Typically, the seepages are tarry (asphaltlike), but a young seepage, or one warmed up by the sun, may become more liquid and flow. In 1864, the chemist Benjamin Silliman, Jr., remarked that in the Rancho Ojai area of California, "the oil is struggling to the surface at every available point and is running down the rivers for miles and miles."

Modern geologists regard oil seeps as proof that an oil-bearing rock is in the region. However, they do not necessarily mark a good place to drill for oil. An oil seep, after all, is a place where the oil is escaping to the surface. It escapes because the trap rock above the oil reservoir has been breached by erosion or faulting. The more prolific the seeping, and the longer it has been going on, the less oil is left to be drilled.

Oil seeps are often associated with water springs, possibly because water springs are also formed as a result of outcropping and faulting. The oil forms an iridescent film on the spring water. If the water is stagnant, the oil may accumulate as a semisolid mass that remains after the oil evaporates.

Gas can also seep to the surface. Gas seepages are easiest to detect when they occur underwater, forming visible bubbles. Thus, gas seepages are most often spotted in swamps, streams, lakes, and coastal waters. Bear in mind that gas often travels greater distances than does oil.

Escaping oil and gas can catch fire, baking nearby rocks such as clays to give them a burnt appearance.

A mud volcano can cover an area of several square miles and be more than a thousand feet tall. It is a cone of mud through which gas escapes, perhaps through cracks in a layer of clay. As the gas rises, it mixes with the clay and ground water to form a mud, which erupts under the pressure of the escaping gas. Mud volcanoes have been found in the Baku region beside the Caspian sea, on the Arakan coast of Burma, on the island of Trinidad, and in Rumania.

Gas or oil may be found, not only in a well drilled for the purpose of finding oil, but also in a water or salt well. In major oil producing regions, minor oil showings may be found in nearly every exploratory well. Even if a showing itself is too minor for the well in question to be commercially viable, the driller may hope that the showing indicates that the well is on the edge of a pool.

Anticlines and Geological Mapping

Beginning in 1861, geologists speculated that anticlines—rooflike arches (folds) of rock—could, if a layer of impermeable rock (the "trap" layer) overlaid a porous, oil-soaked layer (the "reservoir" layer), prevent the oil from escaping. In 1913, Charles Gould pointed out that all of Oklahoma's big pools lay under anticlines, and the rush to find anticlines began. The Mannington, West Virginia, oil field was one of the first discoveries made as a result of applying this geological knowledge.

The ability of an anticline to trap oil into a commercially exploitable pool is dependent on many factors. Oil is usually not associated with large anticlines, i.e., mountain ranges. If the anticline is small, the amount of oil trapped may be insignificant. If the anticline's slopes are shallow, oil may escape, especially if assisted by a regional dip or by groundwater movement. If the anticline's slopes are steep, there may be little room to drill. If the anticline has been eroded or fractured, oil once trapped there may have escaped. If an anticline were formed too many millennia after oil entered the reservoir layer, the oil may have moved on before the trap was formed.

If an anticline traps gas as well as oil, the gas will be at the top. That means that the center of an anticline may produce gas, while wells on the flanks yield up petroleum.

A young anticline will form a hill-like surface structure. However, the geologist cannot safely assume that hills are anticlines and that valleys or plains are not. As a result of erosion, an anticline may be leveled, or even become a valley. For that matter, a syncline (the opposite of an anticline) can become a hill.

Therefore, to be sure whether an anticline is present, one must map the subsurface layers of rock. Mapping the subsurface geology is easiest in hill country (especially the western badlands), where there are numerous outcrops and cliff faces. Mineshafts and road cuts can also be revealing. In farmland, information can be gleaned by descending into irrigation ditches and water wells, as well as by studying occasional outcrops. Pits can be dug, or shallow holes (called "strat" holes) drilled, to gain more information. In forests, swamps, and jungles, of course, the rock formations are well hidden, and digging is also difficult.

If an anticline is fully exposed, you can "walk the bed," that is, trace one of its layers as it rises upward, levels off, and then dips back down. However, it is more likely that only bits and pieces of the structure are exposed. The geologist needs to be able to recognize that a rock layer at outcrop A is part of the same bed as a particular rock layer at outcrop B. Hence, specimens will be collected and carefully compared.

Care must be taken not to confuse two rocks that are similar in appearance but laid down in different geological periods. Fossils can be very useful in dating a rock layer. If the beds are correlated correctly, the geologist can compare the height of a bed, relative to sea level, at different points, and thereby discern whether an anticline is present. Unless distorted by later folding or faulting, the bed will be at its shallowest at the point corresponding to the crest of the anticline, and deeper elsewhere.

The ages of outcrop rocks can be an important clue as to the presence of an anticline. If an anticline is present, and has been eroded down to a plain, older rocks will be exposed at the center of the anticline, and younger rocks on its flanks.

Faulting

A fault is a break in the continuity of a stratified rock. If you broke a plank of wood, and then stuck something underneath one half so the plank pieces no longer lined up, that would resemble a fault.

Faults can be bad news or good news for the petroleum geologist. The bad news is that a fault can break open an anticline, giving the oil a chance to escape along the gap between the fault blocks. The good news is that the faulting can result in an impermeable rock layer being moved alongside a reservoir rock layer, preventing oil from escaping on that side. They can thus help to form a trap and even, in some cases, form traps all by themselves.

Faults can also break up what would otherwise be a single reservoir into several noncommunicating sections. If so, then each section will have to be drilled by at least one well for the entire reservoir to be drained.

Stratigraphic Traps

The term "stratigraphic traps" refers to various kinds of traps that are not formed by folding or faulting.

Paleogeomorphic Traps are aptly named, "buried landscapes," and they are derived from ancient coral reefs and sand bars. Corals are invertebrate sea creatures that form limestone skeletons. When the corals die, their skeletons accumulate to form hill-like coral reefs. In the meantime, their soft parts decay to form oil, which permeates the porous limestone. If the reef is buried by fine silt, which is compacted to form a fine-grained (impermeable) sedimentary rock, the oil will be trapped in the reef.

Sand bars are often found offshore. These sand bars can act as oil reservoirs if they, too, are covered over by silt. Ancient sand bars are the origin of Kansas' shoestring sands.

When one layer after another are laid in parallel, i.e., running in the same direction, they are said to "conform" to each other. If strata are eroded, resubmerged, and then covered with the new sediment, chances are that the new layers will have a different orientation. If the old strata were tilted, and the new strata are horizontal, oil can be sealed off where the old and new layers meet. This is called an "unconformity trap".

The grain size of sediment can change within a rock layer, leading ultimately to a change in permeability. This can prevent the oil from spreading out within the layer. If the oil-bearing layer is capped by an impermeable layer, the "facies-change" trap is complete.

A rock layer will not necessarily have the same thickness throughout. Often, sandstones will have a lenslike cross-section, pinching out at the edges. If the overlying rock is impermeable, it will seal off both the top and the flanks of the sandstone, resulting in a viable "pinch-out" oil trap.

It is relatively common for the basic kinds of traps to be combined within a single oil field. An anticline and a fault, or a fault and an unconformity, may work together to trap oil.

Salt Domes

Sometimes, a deep-lying bed of salt will be pushed up, perhaps as much as 10,000 feet, to form a great dome. As this salt dome rises, it pushes through the overlying rocks. The rocks to either side will be tilted upward toward the dome, like the wake left by a passing ship. Since the salt is impervious to oil, oil rising along one of these tilted layers will stop, and be trapped, when it reaches the dome. Above, the dome, the layers of rock will be folded, forming an upside-down U much like an anticline. Here, too, oil can be trapped.

The first and perhaps the most famous of the salt dome fields was Spindletop, but there are many salt dome fields along the Gulf Coast in Texas and Louisiana. They are also found in the Zechstein basin of Germany.

Geophysical Prospecting

In the mid-1920s, gravimeters, magnetometers and seismometers became important tools of the trade. The seismometer is the most effective of these devices, as it can detect a hidden anticline, i.e, one that does not outcrop. To use a seismometer, you must set off an explosion (in effect, an artificial earthquake). When the sound wave strikes the boundary between two rock layers, the sound wave is reflected (and refracted), and you can detect this.

Unfortunately, I don't think seismological prospecting will be practical in the 163x universe within a reasonable time frame. While I have no doubt that a pendulum-type seismograph can be constructed, I doubt that the necessary sensitivity and precision can be achieved.

Even if that barrier is surmounted, we will need to learn how to interpret the seismograms; this is very unlikely to be explained in a public library book. In effect, we will need to rediscover geophysics. It will happen, but not anytime soon.

Percussive Drilling

If the oil has seeped to the surface, you may not need to drill a well at all. Depending on whether it is in a liquid or solid state, it can be scooped out or dug out.

In percussive drilling, the rock is fractured by repeated "hammer-blows" from heavy cutting tools. Such drilling was first performed in North America in 1808, using a device called a spring pole. This was a sapling bent to hang over the hole. (While the spring pole was initially used to drill for brine, the technique was readily carried over to petroleum extraction.) A rope would be tied to the sapling, hanging over the hole, and the drill would be tied to the free end. A second rope would also be tied to the sapling, but its free end would be tied into a loop. The operator would put his foot in the loop, and kick down, driving the drill into the hole. The natural springiness of the sapling would pull the drill back up, and the operation would be repeated. From time to time, you would replace the drilling tool with a bailer, so you could clear out the accumulated debris. To facilitate this, a large wooden tripod, with a hanging pulley at the top, was placed over the well hole. This tripod was the precursor of the derrick.

Drilling with a spring pole rig was slow work (one to three feet a day), and spring poles were suitable only for drilling shallow wells, usually less than 300 feet deep. On the other hand, the investment in materials was minimal, and the well could be drilled by one person. This is the drilling strategy that a farmer might use on his or her own land.

Could a spring pole rig be used successfully at Wietze? I can't say for sure, but I think it significant that in 1991, the Petroleum Museum in Wietze issued a commemorative medal that depicts the tripod of a spring pole rig on one side.

The spring pole rig was the precursor of the "cable tool" rig, in the sense that both break rock by percussion. The cable tool rig was so called because the drill (the "tool") was at the end of a cable. The cable ran up to a pulley mounted on the cross arm of a mast, and then down to the "tool string" hovering over the well hole. With the cable tool rig, the rock was worn away by the hammering effect of dropping the tool on it.

The tool string of the cable rig was raised by animal or steam power. For example, a walking horse or ox could pull a sweep (described by Agricola in 1556) or walk a treadmill. Or a steam engine could turn a capstan. The cable was initially a manila rope, and later steel wire.

In 1880, the total weight of the downhole tools was around 2,100 pounds. The drill bit was around four feet long and 140 pounds, and had a chisellike cutting edge. The heaviest tool, the auger stem (over 1,000 pounds), screwed into the bit, and increased the rigidity (and weight) of the drill. Above it were the "jars," which have a lower link that strikes against the auger stem on the upstroke, helping to dislodge (jar") the bit if it is stuck in the rock. The sinker bar, above the jars, has a similar purpose. The topmost downhole tool was the rope socket, which secured the tool string to the cable. The tool string is described in Grantville's copy of the 1911 Encyclopedia Britannica, which also comments on how the different components work together.

Percussive drilling techniques were known down-time. In the Artois region of France, a water well was drilled in 1126 by hammering down a rod with a chisel edge at the other end. (Gies, 112). A similar technique had previously been developed by the Chinese to drill both brine and natural gas wells, and it is a matter of scholarly debate whether the French were innovators or copycats.

I have not found a record of pre-ROF spring pole drilling in Europe. However, spring pole lathes were used in the Renaissance so, once a down-time engineer had the incentive to drill, this would not be a tremendous intellectual leap. However, the spring pole rigs would probably be used only by farmers on their own property, or on long distance expeditions on which you don't want to transport a full drilling rig yet expect that the oil will be found at a shallow depth.

Can the USE build cable tool rigs right away? I assume that cable is available, but if it isn't, you can still use a sturdy rope. Grantville residents know how to construct steam engines, which could provide the motive force. But animal power is an alternative. Then you need a connecting mechanism, such as a walking beam, to translate the steam engine's action into a pull-and-relax on the cable. This is well within down-time engineering skills (there are mills in pre-ROF Europe). Finally, you need the parts of the tool string. I believe that if you can cast cannon, you can cast the cable tools.

There are two basic problems with cable tool drilling. First, one has to stop every few feet to replace the tool string with a bailer, to haul out the debris. Second, the tool string could come loose inside the well hole. One then has to fish it out, which is easier said than done. As a result of these factors, the average pre-1940 cable tool drilling rate was about three feet per day, and the maximum rate, about ten feet a day. (Williamson I, 97; Oil Century, p. 93) A modern cable rig can pierce sixty feet a day (Anderson, 129).

It is often stated that cable tool rigs can be used to drill only to 2,000-4,000 feet. However, in 1953, a cable tool rig plumbed a depth of 11,145 feet.

Rotary Drilling

In the 1890s, oil drillers began experimenting with a "rotary rig." In this rig, the rock was worn away by the cutting action of a spinning bit. The bit is attached to a hollow drilling rod, ...