2.2.1 The Battle of Fredericksburg and the Roberts Petroleum Torpedo Company

Following the first drilling of the first commercially successful oil well on the northern bank of Oil Creek in Titusville, Pennsylvania, by Edwin Drake in August of 1859, pressure to create and develop new technologies was constant.

The next large advance in technology came through an unlikely person: Edward A.L. Roberts (1829–1881). In 1847 at age 17, Roberts enlisted as a private with Col. Pitcher’s company for the Mexican War and after 22 months was discharged honorably. He entered the Academy of Armenia, New York, for 1 year at age 19. He then went into dentistry and invented a mineral substance to make continuous gum teeth. He also invented several other dental devices, and in 1859 he perfected an oxyhydrogen blowpipe.

During the Civil War Edward A.L. Roberts raised regiments. In 1862 he was given the rank of lieutenant colonel of the 29th New Jersey Volunteers and commanded that unit (Figure 2.2). He went on to organize other units and was completely occupied with military duties. Roberts made his first drawing of the Roberts Well Torpedo in 1862 after hearing about oil production in Titusville and applied for the patent in November 1864. Colonel Edward A. L. Roberts and his brother Walter Brooke Roberts arrived in Titusville from New York in 1864, and the Roberts brothers formed the company called Roberts Torpedo Petroleum Co. The company made torpedoes, fired them, built magazines, and manufactured nitroglycerin (Figure 2.3). Taking advantage of improved explosives technology from the Civil War, the Roberts Petroleum Torpedo Company was formed in 1865 to stimulate recovery from shallow oil wells by “shooting” the well using nitroglycerin (Figures 2.4 and 2.5). Roberts’ first attempt was in 1866 at Ladies’ Well, located on Watson’s Flat, about a half mile north of Drake’s famous discovery.

The two men had six torpedoes filled with black powder, and with water borehole filled with a tamping column of water, the charge was set off at a depth of 463 ft (141 m). Although the story is that Roberts developed the water‐tamping idea from watching bombs land in the Rappahannock River at the Battle of Fredericksburg in Virginia, Roberts was nowhere near Fredericksburg during the actual battle. The use of water tampering helped keep the explosive activity down in the well where it would do the most good. In late 1866 they would achieve greater success at the nearby Woodin well, where two torpedoes were used in a dry hole at Blood Farm, and following shooting the well production was at 80 barrels a day.

The technique was called “shooting a well.” Shortly thereafter, the Roberts Torpedo Company was formed, and they acquired the rights to use a new explosive, nitroglycerin, from the Swiss chemist Alfred Nobel (Figure 2.6). Billing $100–200 per charge, plus a royalty of 1/15th of a new well, Roberts was successful in obtaining a patent in 1866 and protecting his patent, spending hundreds of thousands of dollars in lawsuits for those that used his torpedoes to reopen wells (Figure 2.7). Due to patent infringements by others, E.A.L. Roberts was forced to engage in significant litigation but persevered, consuming much of his time. At one time there were as many as 2000 active cases involving his patent being heard in the courts. In the following years, Roberts claimed to have spent a quarter of a million dollars in litigation over his patent and at the time was responsible for more lawsuits nationwide than any plaintiff.

Although Roberts was not the first to test explosives in new oil wells throughout western Pennsylvania, he was successful and had the foresight to patent his idea. George Van Vliet of Pleasantville, Venango County, claimed to have been shooting wells for more than 30 years. Although Van Vliet had shot his first well at the age of 19 in 1864, prior to the arrival of Roberts brothers torpedo, using a cylindrical explosive device in form and of a size suitable for insertion into the local oil wells to the area, an agreement allowed him to work certain fields of Pithole (Figure 2.8), Shamburg, and Petroleum Centre (also spelled Petroleum Center) in Venango County, Pennsylvania, unbothered by Roberts (McLaurin 1902).

The fracturing technique is characterized in the 1865 Articles of Association, By‐Laws and Prospectus of the Roberts Petroleum Torpedo Company: “The invention consist of a torpedo, cylindrical in form, and of a size suitable for the introduction into the bore of an oil well of the usual diameter, To it is attached a simple and ingenious contrivances for effecting its explosion by percussion,…infallibly accomplished at any depth of submission.” The process involved transporting nitro in specially designed protective packaging on nitro wagons to the well site. The number of 4‐ft shells was determined based on depth and geologic conditions at the bottom of the borehole. Each shell was first filled with water, and then the heavier nitro was added, which sank to the bottom of the shell, causing water to spill over the shell’s top rim. This reduced the chance that nitro would be splashed during pouring. The shells were then lowered down the hole, and a trigger unit, referred to as a “squib,” was also loaded with nitro with a percussion cap rested on top of the shell. The well was then filled with water (at least 50 ft above the top of the shell). An 8‐lb cast iron unit called the “go‐devil” was dropped in the well, and the shooter galloped away “going like the devil.” As noted by Lewis (1934), “A unit quantity of solid or liquid nitroglycerin on explosion produces more than 7,000 times its own volume at normal temperature…but, at the moment of explosion, temperature is raised to more than 6,000 degrees Fahrenheit. It evolves at a rate of 23,600 feet per second,” or 16 090 mi h⁻¹ (25 894 km h).

This technique would continue to develop and subsequently be used for both oil and gas wells. It is interesting to note that direct corporate descendants of the original Roberts Petroleum Torpedo Company – the Otto Cupler Company – are still shooting wells near Titusville today.

The early artificial fracturing services offered by the Roberts Torpedo Company and others radically changed the economics of producing crude oil wells and, as a class of businesses, represented one of the first oil field service sectors with technical expertise to support oil and gas operators. The early techniques of artificial fracturing of reservoirs allowed for wells to continue producing, which, combined with improved drilling methods and a significant increase in the number of producing wells, created an oversupply of crude oil that far exceeded the demand. In 1859, the year of the Drake well, the cost of a barrel (42 gal or 159 l) of crude oil averaged $16.00. By 1860 the price was $9.59, which plunged to $0.49 and 1.05 per barrel in 1861 and 1862, starting the first oil price collapse. From 1866, the year of the Roberts Torpedo Company patent, to 1878, the price of crude oil ranged from a high of $5.64 per barrel in 1869 to a low of $1.17 per barrel in 1874 and 1878. From 1879 to 1915, the average price of a barrel of crude oil exceeded $1.00 only during three years, likely a reflection of oversupply. Similar price drops due in part to improved artificial fracturing techniques and crude oil oversupply occurred from 2013 to 2016. A summary chart and table of US crude oil prices (US EIA 2018) from 1859 to 2016 are included in Appendix K.

2.2.2 Well Casing Perforators

With the onslaught to drill new wells and reinvigorate old wells, a variety of perforating technologies were developed (Figure 2.9). Cement well casing was developed in 1919 by Erle P. Halliburton’s New Method Oil Well Cementing Company, Duncan, Oklahoma. The purpose of the casing was to isolate wellbore zones and guard against collapse. It was understood by the 1920s that almost any drilling process will create some damage to the formation adjacent to the wellbore; thus it was important that perforation techniques bypassed the damaged area. To perforate the casing and enhance production of oil or gas, the US Patent Office records many technologies designed to solve the problem of safely perforating well casing. In 1902, one invention (Patent No. 702,128) relied upon a scissors‐like expanding mechanism to drive and then retract “perforating levers” through the casing (Figure 2.10).

By the 1930s, “bullet” devices using projectiles, commonly steel bullets, became the most popular. In 1939, a device that perforated casing after it has been installed by firing downhole projectiles was designed by Ira J. McCullough of Los Angeles. McCullough received two patents for his multiple bullet‐shot casing perforator and mechanical firing system and would report “It is the object of my invention to provide a device for perforating a well after the casing has been installed in the well in which there is plurality of projectiles, each of which is adapted to be propelled by the burning of a separate charge of powder,…. The charges of powder are simultaneously ignited in order that all of the projectiles will be shot or projected from the apparatus at substantially the same time and with ample force and velocity to penetrate a plurality of casings and intervening walls of cement.” McCullough’s device (Patent No. 2155322) also included a “disconnectable means” that – once the charges are lowered into the borehole – can render percussion inoperative as “a safeguard against accidental or inadvertent operation.”

2.2.3 The First Perforating Guns

A new and effective casing perforation technique was needed to enhance the production of oil and gas from cased wells, and in 1930, two oil field tool salesmen, Bill Lane and Walt Wells, envisioned a tool that would shoot steel bullets through casing and into the adjacent formation. Their efforts would lead to the creation of a multiple‐shot perforator that fired bullets individually by electrical detonation of the powder charges. By late 1935, the company Lane‐Wells was becoming the leading provider of well perforation technology.

An August 1938 Popular Science Monthly article describes exploration and production technologies used for “the deepest hole man has ever made in the crust of the earth” – a 15 000‐ft (4 572‐m) well in Wasco, California (Figure 2.11). “Apparently the well had just missed an oil pool, blocked off from it by a formation impervious to oil,” notes the article.

While improved drilling methods made deeper wells possible, the “underground machine gun” was not really a machine gun, but a torpedo‐shaped cylinder of steel, studded with recessed knobs along its outer shell, which was lowered down the well with a cable. Each knob formed the barrel of a pistol. Once at the desired depth, an operator at the surface closed an electric switch. Slugs of solid steel punctured the well casing and ripped through the surrounding sand “As if released from a bullet riddled tank, oil gushed through the holes and up the pipe….” Several multiple gun barrel‐type devices would be developed to enhance development and control well development issues such as “sanding up.”

Modern‐day perforators basically fall into two types: (i) overbalanced perforating and (ii) underbalanced perforating. Overbalanced perforating reflects the weight of the wellbore column being greater than that of the reservoir pressure, thus ensuring that the well does not cause flowing of oil or gas immediately after perforation. However, it may have the effect of damaging the formation due to forced entry of wellbore fluid or mud into the reservoir. Today’s perforating guns include casing guns, expendable guns, retrievable guns, and high shot density guns. Modern types of perforators are presented in Table 2.2.

2.2.4 Bazooka Technology

The tank was a new and terrible weapon during World War I, and by the 1930s, further advancements in German armor had military planners in England and France working on development of a counter weapon. A Swiss Army veteran and chemical engineer, Henry Mohaupt, worked on this problem and brought his research to America, where the US Army’s Ordnance Department put him in charge of its secret program to develop an anti‐tank weapon. It was Mohaupt’s idea to use a conically hollowed‐out explosive charge to direct and focus the detonation’s energy that ultimately produced a rocket grenade used in the Army’s 60‐mm M1A1 Rocket Launcher, commonly known to all as the GI’s bazooka (Figure 2.12). Realizing the potential industrial use of this military technology, after the war, Mohaupt was recruited by the Well Explosives Company, located in Fort Worth, Texas. His patent submission, dated 24 September 1951, for a “Shaped Charge Assembly and Gun” brought bazooka technology to the oil field (Figures 2.13a and 2.13b; US Patent Office No. 2,947,250, 1960).

Since any drilling process creates some damage to the formation adjacent to the borehole, bypassing this damage is key when perforating. Mohaupt explained in his patent application that “This invention relates to improvements in means for perforating casing in wells and for perforating and fracturing earth formations around well bores….” Focused explosive energy was found to easily cut through casing and strata. In later years, such companies as Welex Jet Services (formerly Well Explosives Company), DuPont, and others continued to explore and develop this technology.

2.2.5 Matrix Acidizing Treatment

By the 1930s, a concept developed with the injection of a nonexplosive fluid, or acid, that enhanced production by creating a flow channel in the formation to the well. Along with shooting, acidizing was one of the earliest methods developed for increasing well production.

Matrix simulation is a technique wherein a solvent is injected into the formation to dissolve some of the material present, which improves or increases the permeability of the formation, thus improving production. Important to note is that such techniques are called “matrix” treatments because the solvent is injected at pressures below that which would cause fracturing (i.e. below the parting pressure). The objective is to significantly enhance or recover permeability near the wellbore, rather than affect a significant portion of the reservoir. Acidizing is the most common matrix simulation technique in which an acid solution is injected into the formation with the intent to dissolve certain minerals in the formation. Other solvents used include organic solvents with the purpose of dissolving asphaltenes, paraffins, waxes, or other organic materials.

The most common acids used are hydrochloric acid (HCl) and hydrofluoric acid (HF). HCl is used primarily to dissolve carbonate minerals. Mixtures of HCl and hydrofluoric acid (HF) are used to attack silicate minerals such as clays and feldspars. Other acids, particularly some weak organic acids, are used in special applications, such as high temperature wells. Being a near‐wellbore treatment, in sandstone formations, acid reaction is within 1 ft of the wellbore, whereas in carbonates, acid reaction is within a few inches to as much as 10 ft from the wellbore. Thus, this treatment is of limited benefit in an undamaged well but significantly enhanced productivity where near‐wellbore damage is present.

2.2.6 The Sulfur King

In 1890 the German‐born Herman Frasch (1851–1914; Figure 2.14) invented a new way of mining for sulfur at Sulphur, Louisiana, which within 20 years changed the United States from an importer of the mineral to a country with such an abundant new supply that Frasch‐produced sulfur dominated the world market. Frasch is also known for his development of the sulfur mining process – a method for removing sulfur from crude oil, both referred to as the Frasch process, and inventing wax paper. Frasch is also given credit for assisting in the winning of World War I by making sulfur abundant and thus putting the United States in a position to be able to manufacture munitions quickly and cheaply. When John D. Rockefeller found he had a virtually worthless oil field in Ohio, it was Frasch who saved the day. So‐called “sour” oil was so named because of too much sulfur in the mix. Frasch figured out how to extract that sulfur. That made the difference between Rockefeller getting 16 cents per barrel and getting over a dollar. With over 25 million barrels at stake, that amounted to quite a fortune! Frasch would be known as “the Sulfur King” (Sutton and Keene 2013).

The idea of using acid to dissolve the limestone – thus opening channels through which the oil could flow into the well first – appears to have been developed by Herman Frasch, with a half interest being assigned to John W. Van Dyke (US Patent No. 556,669, issued on 17 March 1896). The essence of this patent was the introduction into the oil well of a large solution of hydrochloric acid under pressure, with freshwater being added later to force the acid further into the limestone (Figure 2.15). Frasch recommended the use of commercial hydrochloric acid containing from 30 to 40% by weight of the acid gas HCl, and he further recommended that the acid remain in the well for 12 hours. A suitably arranged packer was to be used to confine the acid to the lower or oil‐yielding portion of the well hole.

Frasch also recognized that hydrochloric acid was likely to corrode the metal well equipment. Hence the patent suggested that the regular well tubing be removed and that an enameled or lead‐lined pipe be inserted to conduct the acid down into the well, “or it may be otherwise made proof against corrosion.” An additional suggestion was that an alkaline liquid be introduced to neutralize the acid after it had performed its function.

Frasch in his 1896 patent described the technique first used in 1895 in which HCl is injected into a limestone formation, where it reacts to create channels and enhanced porosity and permeability within the rock. His process required the pipe to be lined with rubber or some other corrosion‐resistant coating. Corrosion inhibitors were not envisioned as yet. Although initial impressive results were reported, their actual use declined likely due to corrosion. It would be 30 years later when the Gypsy Oil Company found a way to inhibit HCl and remove calcium sulfate deposits. The inhibitor was developed earlier in the steel industry for the acid pickling of metals.

Frasch’s method proved successful in disintegrating limestone rock and increasing the flow of oil. The record shows that at least fourteen commercial wells near Lima, Ohio, were treated with this process in 1895 and 1896, resulting in substantial production increases in most instances. Wide publicity was given to these operations. But despite this success, Frasch and Van Dyke soon discontinued their work along these lines. The reasons for this abandonment are not clear, but a relatively undeveloped oil industry may be the cause, although others contended that the method was so cumbersome and expensive that it was commercially impracticable.

In 1885 Frasch entered upon experiments leading to one of his most important discoveries, the purification of sulfur‐tainted oils, such as are found in the oil fields of Canada, Ohio, Indiana, and Illinois. The presence of sulfur in these oils greatly limited their range of utility because of the offensive odors and suffocating fumes liberated when they were burned. Such defects reduced their value to the lowest terms, the usual price at the wells being as low as 14 cents per barrel. Apart from the presence of these impurities, however, the oils were of excellent quality, capable of refinement into illuminating oils of high grade, as well as into the coarser products fit only for fuel purposes.

Frasch nearly duplicated his achievements with sulfurized oil in his successful purification of the California oils, which were found charged with aromatic hydrocarbon compounds to such an extent as to interfere with their full potential and usefulness. Frasch’s solution for this difficulty was a simple chemical one by which the aromatics were easily separated from the aliphatic and acyclic constituents by transferring the former into their sulfo acids by the use of smoking sulfuric acid.

On another occasion Frasch was appealed to devise a method for rejuvenating “tired wells.” In Pennsylvania the usual method had been to drop a charge of nitroglycerin into the well to shatter the surrounding rock by explosion and thus promote new flow of oil. Geological considerations relating principally to the quality of the rock as well as to its depth below the surface rendered this procedure inapplicable to the Indiana and Ohio wells. Hydrochloric or sulfuric acid, one or the other, according to specified conditions, was to be poured down the well, and the well opening securely plugged. The result was that the generation of gases, due to the chemical reactions taking place in the subterranean depths, acted to shatter the surrounding rocks and open up new oil cavities, quite as effectively as and more certainly than by the use of explosives. This took hold in the industry during the 1930s.

2.2.7 Modern Age of Acidizing

The modern era of acidizing began on 11 February 1932, with work being done by the Dow Chemical Company. Early treatments were performed in an attempt to dispose of surplus HCl; however, these acid disposal wells were soon observed to accept fluids at an increasing rate. Later treatments on brine‐producing wells at the Dow plant located in Midland, Michigan, resulted in increased brine flow. It was this observation that led to using this process for enhancing oil production.

The treatment consisted of siphoning 500 gal (1893 l) of HCl containing 2 gal (8 l) of an arsenic inhibitor into a well owned by Pure Oil Company and displaced it with an oil flush. The goal was an attempt to dispose of excess HCl, but it was also noted that these acid disposal wells accepted fluids. This event was the first use of an inhibited acid within a limestone formation, producing 16 barrels of oil per day from a well that was previously dry. The use of inhibited acid to treat oil wells spread quickly, and the Dow Well Services Group was formed to exploit this new process. The first two words of the company’s name were combined, becoming Dowell, Inc., in November 1932. Other service companies soon followed. Within three years, acidizing was practiced widely.

The first hydraulic fracturing treatments were probably performed with acid, although they were not recognized at the time. Wells in tight carbonate formations would usually not accept acid until a critical pressure was reached. However, after this pressure was reached, acid could be easily injected at high rates. It was later recognized that these wells had been hydraulically fractured. For this reason, later hydraulic fracturing patents were never enforced against acid fracturing treatments.

2.3.1 The Hydrafrac Process

The hydrafrac process consisted of two steps (Figures 2.16a and 2.16b). The first step consisted of the injection of “a viscous liquid containing a granular material, such as sand for a propping agent, high hydraulic pressure to fracture the formation.” The second step was to cause “the viscous liquid to change from a high to a low viscosity so that it may be readily displaced.” The initial viscous liquid used consisted of an oil such as crude oil or gasoline, with an added “bodying” agent. Napalm gel was used in the majority of experiments reflecting to availability and cost.

The hydrafrac process was applied to wells partially depleted, but it was also remarked that new wells could improve their productivity by application of the process. The concluding statement by Clark in his 1949 paper was: “It is significant that the value of the oil and gas produced to date through the benefits of this process has already exceeded the combined cost of research, development, and all field tests.”

Other important papers published during the mid‐century included Fast (1952), Howard and Fast (1950), Farris (1946), and Hubbert and Willis (1957). Concurrent with Clark’s work in 1949, other important studies were being undertaken including evaluating the time spent for cement to set and gain a given minimum strength (Fast 1952) and the possibility of squeezing outward into a formation an impermeable lens or pancake of cement at select elevations in a wellbore to control the migration of undesirable fluids into the producing well (Howard and Fast 1950). These techniques were mechanically related to three other phenomena: (i) pressure parting in water injection wells in secondary recovery operations, (ii) lost circulation during drilling, and (iii) the breakdown of formations during squeeze‐cementing operations. These three phenomena all appeared to involve the formation of open fractures by pressure applied in a wellbore. Hubbert and Willis (1957) noted that hydraulic fracturing techniques for well stimulation were one of the major developments in petroleum engineering over the past decade. In order to evaluate the ability of a hydrafrac treatment to effect a sustained increase in well production, data were accumulated on the first 65 wells in 26 fields treated by Stanolind, and the treatment was found to be capable of affecting a sustained increase in production (Farris 1946). Since Clark’s work in 1949, its use has progressively expanded so that, by the end of 1955, more than 100 000 individual treatments had been performed (Hubbert and Willis 1957). Gold (2014) would note this early period of innovation and well stimulation would lessen the role of the wildcatter and the beginning of the age of the petroleum engineer.

The first hydraulic fracturing solutions were oil based and included crude oil and (or) gasoline thickened with napalm. A summary chart of hydraulic activity from 1945 to 2015 (Figure 2.17a–c) shows some of the variations with the technology over seventy years. About 92% of the nearly 24 400 early treatment fluids were listed as “unknown” before 1953, and of those treatment fluids reported (~8%), a majority were described as water (32%), oil (30%), explosives (14%), and acid (12%)(Figure 2.17b). This is consistent with what was reported in the literature and reflects a transition during this time from fracturing using explosives or acid etching (without the use of a proppant) to hydraulic fracturing using the injection of oil‐based fluids and sand to prop open the fractures. The latter process developed initially for well stimulation within sandstone formations. Furthermore, most of these treatments were applied to vertical wells to stimulate oil production.

Water was introduced as a fracturing fluid in 1953, which corresponds to an increase in the number of records of both hydraulic fracturing (Figure 2.17a) and water‐based treatments. An increase of other water‐based fluids would follow and include specialized service company formulations (i.e. My‐T‐Frac). Proppant use with sand also followed and considered the most common proppant (99% of reported treatments). The use of ceramics, resin‐coated ceramics, resin‐coated sand, and bauxite made up <1%.

The use of water‐based fluids also coincides with the evolution of a number of different additives, each designed to optimize hydraulic fracturing, depending on commodity type and reservoir attributes. Soon after the emergence of water as a hydraulic fracturing treatment fluid base, gelling agents (i.e. guar gum and cellulose derivatives) used to increase viscosity appeared (Figure 2.17c). To increase the effective weight of water‐soluble polymers, making solutions capable of suspending proppants at low temperature, these fluids were crosslinked with potassium pyroantimonate (H₂K₂O₇Sb₂) at low pH, borate (BO₃⁻³) at high pH, or aluminum.

2.4.1 Project Plowshare

On 6 June 1958, the AEC publicly announced the establishment of the Plowshare Program, named for the biblical injunction to ensure peace by beating swords into plowshares (Isaiah 2:4).

And they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war any more.

The program objective was to use nuclear explosives for civilian as opposed to military purposes. In the end, although less dramatic than nuclear excavation, the most promising use for nuclear explosions proved to be for stimulation of natural gas production.

The Plowshare Program commenced in 1958 and continued through 1975. From 1961 to 1973, researchers carried out 27 separate experiments under the Plowshare Program, resulting in 35 nuclear detonations. Most of the experiments focused on creating craters and canals, with some optimistic applications such as widening the Panama Canal. Individual endeavors pertaining to fracturing to enhance gas and oil well stimulation, as employed throughout the 1960s and early 1970s, included numerous projects, many of which were not executed. Individual projects included Pinot, oil sands, oil shale, Project Gasbuggy, Project Dragon Trail Study, Project Ketch, Project Bronco Study, Project Wagon Wheel, Project Wasp, Rulison nuclear test, and Project Rio Blanco (Table 2.3). Nuclear tests were mostly conducted in Nevada but also took place in the petroleum fields of New Mexico and Colorado and were planned but never implemented in Wyoming.

2.4.2 Project Gasbuggy

All this nuclear interest actually started taking form in 1954 when the El Paso Natural Gas (EPNG) Company discovered a gas field between 7 500 and 10 700 ft (2 286–3 261 m) below the surface south of Pinedale in Sublette County, Wyoming. Six wells were drilled, and it was estimated that approximately four trillion standard cubic feet of natural gas comprised the field; however, the natural gas was in low‐permeability sandstone formations. The cost of available technology to fracture the rock did not justify building a pipeline to the field. EPNG subsequently proposed a nuclear stimulation concept for the Pinedale unit to the AEC in 1958.

After Wyoming was New Mexico with a project known as Project Gasbuggy. This project included experts from the AEC, the US Bureau of Mines, and EPNG. The actual project was essentially the first of a series of underground nuclear detonations carried out by the AEC on 10 December 1967 in rural northern New Mexico to test the feasibility of using nuclear explosions to release natural gas trapped in dense shale deposits (Figures 2.18 and 2.19).

Highly radioactive material in the area was subsequently removed, and the site is now level ground safe to approach at the surface. Drilling or digging in the area however is prohibited. In 1978, a placard, noting ground zero, was installed at the site. The placard is publicly accessible via the dirt road New Mexico F.S. 357/Indian J10 through Carson National Forest.

2.4.3 Project Rulison and Project Rio Blanco

Two later tests took place in Colorado: one in 1969 called Project Rulison and in 1973 called Project Rio Blanco. Project Rulison, near Rulison, Colorado, used a 43‐kiloton nuclear device almost 8500 ft (2591 m) underground to produce commercially viable amounts of natural gas. Project Rio Blanco, northwest of Rifle, Colorado, was designed to increase natural gas production from low‐permeability sandstone. Project Rio Blanco consisted of nearly 3 simultaneous detonations, each 33 kiloton in a single well. According to the Office of Environmental Management, the explosions occurred at depths of 5838, 6230, and 6689 ft (1779, 1899, and 2039 m) below ground level. It would prove to be the last experiment of the Plowshare Program.

2.4.4 Project Bronco

Another test, called Project Bronco, was proposed but never took place. This test would have consisted of a 50‐kiloton nuclear explosion to fracture deep oil shale deposits. Termination of the Plowshare Program occurred in 1975, stemming from growing concern about adverse environmental impacts and concerns. Although wells were drilled and natural gas was extracted from the site, the gas proved to be too radioactive to be commercially viable.

2.4.5 Project Wagon Wheel

The story does not end in Colorado however, but with EPNG in Wyoming. The results of the Gasbuggy test explosion encouraged EPNG to pursue study of “Project Wagon Wheel.” Cooperating on the project were EPNG, the AEC, and the US Department of Interior as specified in Contract No. AT(26‐1)‐422 between the United States and EPNG, dated 24 December 1968. Project Wagon Wheel differed, however, from Gasbuggy because its goals included obtaining cost information as well as technical information. Gasbuggy’s objectives were to determine the engineering, but not to be a profitable investment.

Project Wagon Wheel was to be Wyoming’s nuclear stimulation project, nestled in Sublette County, Wyoming. Sublette County is located in southwestern Wyoming and in 1970 had a population of 3755. There were 4 towns between 10 and 20 mi (16–32 km) from the proposed blast site.

The Project Wagon Wheel test was initially scheduled for 1973, but as time passed, the date for the test was postponed and then postponed several times thereafter. In September 1973, the AEC announced that “the project is still in the design stage and no execution has been authorized as yet” and that the test would probably not occur before fall 1974. Unlike its predecessors, Project Wagon Wheel was not detonated. Had it been tested, 5 nuclear devices would have been detonated sequentially from bottom to top between 9 220 ft (2 810 m) and 11 570 ft (3 527 m) below the surface (Figure 2.20). The detonations would have created an underground rubble chimney ~2800 ft (853 m) high and about 1000 ft (305 m) in diameter. The five nuclear devices would have been 100 kilotons each and detonated ~5 minutes apart and estimated to be about 35 times as great as the energy of the gas that was expected to be produced. After the blast, 4–6 months would have had to pass before test production of natural gas to allow for the decay of short‐lived radioisotopes, albeit there would be anticipated release of radiation during the 325‐day flaring of the well.

The exact date Project Wagon Wheel died is unclear. President Nixon’s budget for fiscal year 1974 did not include funding for tests under Plowshare, which included Project Wagon Wheel. Had Project Wagon Wheel proceeded, it would have been mild compared with what was planned when EPNG commenced full field production. There could have been as many as 40–50 nuclear detonations a year, some within a mile of Pinedale, Wyoming.

The test well drilled for Project Wagon Wheel was never used in a nuclear test but was employed by EPNG to conduct tests of “massive hydraulic fracturing” (MHF) during 1974 and 1975. MHF was the now familiar method where water was pumped into a well until the pressure of the water caused the rocks to fracture. The study used the well originally drilled for Project Wagon Wheel, but concluded the MHF technique employed was not commercially feasible.

2.4.6 Former Union of Soviet Socialist Republics (USSR) Program

Where the United States pursued stimulation of natural gas with the use of “peaceful nuclear explosions” (PNE), a similar program implemented by the former Union of Soviet Socialist Republics (USSR) targeted oil reservoirs. The three Soviet tests included two reported tests (Soviet Test #1/Butane 1‐1 and Butane 1‐2 and Soviet Test #2/Griffon‐1 and Griffon‐2) and one postulated (Soviet Test #3/Kimberlite‐1). Soviet Test #1 was detonated on 30 March and 10 June 1965 in a carbonate oil and gas reservoir situated in the southwestern part of the former USSR about 200 mi (322 km) east of Kuybyshev. The shot was in an oil‐producing field with an established production history and decline curve. Soviet Test 32 was detonated on 2 and 8 September 1969 in a limestone and dolomite oil reservoir situated about 150 mi south‐southwest of Perm. Soviet Test #3 albeit only postulated was in bituminous shale region of the Salym oil field and situated in the middle Ob region of western Siberia. Soviet Test #3 was the last of the examples with any documentation.

Overall, similar to the US efforts, the Soviet program was technically successful, but not sufficiently successful enough to continue testing and pursue further development of nuclear stimulation technology. In both cases, increasing environmental awareness and concern, and other considerations such as social, economic, political, and military, resulted in termination of such efforts in both countries (Lorenz 2001).

2.4.7 Other Innovations

During the 1960s, hydraulic fracturing well stimulation techniques and strategies continued to evolve. Potassium chloride began to appear in the mid‐1960s for clay stabilization and to lower surface tension in water‐sensitive formations. Before the late 1960s, however, most hydraulic fracturing operations were small and applied to shallow reservoirs, mainly for damage removal (such as scale or paraffin deposited within the wellbore during drilling). In the late 1970s, foam‐based fracturing fluids, often generated using pressurized nitrogen (N₂) or carbon dioxide (CO₂) additives, were also used. This objective was to stimulate shallow low‐pressure zones such as for coalbed methane (CBM) production. Liquid CO₂ was initially introduced in the early 1960s for use with water‐ or oil‐based treatment fluids and later as a sole carrier fluid to gas‐lift the liquid back to the surface after treatment.

2.4.8 Peak Oil

With the rise of the counterculture and environmental movements of the 1960s, oil and gas extraction would go political. The term “peak oil” would exemplify this trend. Peak oil is the point in time when the maximum rate of oil and gas extraction is reached, after which the rate of production is expected to enter terminal decline. It accurately reflects individual production in wells and fields. Initially, every oil and gas well and field exhibits an increase in production and eventually reaches a peak production before production subsequently declines. Enhanced efforts can prolong production, but overall production of each well typically follows a production curve, peaking at one point and then trailing off in an inevitable decline. Despite enhanced recovery, ultimately production decline occurs nonetheless.

Referred to as the Hubbert curve (Figure 2.21), the ultimate production curve showing oil production was first used in models describing peak oil in 1956. Based on his theory, he presented a paper to the 1956 meeting of the American Petroleum Institute in San Antonio, Texas, which predicted that overall petroleum production would peak in the United States between 1965, which he considered most likely, and 1970, which he considered an upper‐bound case. The ultimate potential production of crude oil was estimated to be 1250 billion barrels. Reserve figures presented were based on “oil capable of being extracted by present techniques.” As large‐scale conventional oil and gas production eventually declines as Hubbert predicted, unconventional methods are being used to augment oil and gas supplies. Later, the Hubbert curve was used to describe peak world oil and used for other finite resources as well.

2.5.1 Horizontal Drilling

The technology of horizontal drilling moved into the arsenal of the oil industry in the early 1980s (US EIA 1993). Horizontal drilling is the process of drilling a well from the surface to a subsurface location just above the target oil or gas reservoir called the “kickoff point,” then deviating the wellbore from the vertical plane around a curve to intersect the reservoir at the “entry point” with a near‐horizontal inclination, and remaining within the reservoir until the desired bottom‐hole location is reached (Figure 2.23).

The modern concept of non‐straight line, relatively short‐radius drilling dates back at least to 8 September 1891 when the first US patent for the use of flexible shafts to rotate drilling bits was issued to John S. Campbell (Patent Number 459,152; Figure 2.24). A flexible shaft is a device for transmitting rotary motion between two objects that are not fixed relative to one another. Typically, such devices consist of a rotating wire rope or coil that is flexible but has some torsional stiffness. It may or may not have a covering, which also bends but does not rotate, and may transmit considerable power, or only motion, with negligible power.

Of note is that the prime application described in the patent was dental engines. The patent also carefully covered use of his flexible shafts at much larger and heavier physical scales: “My invention relates more particularly to the flexible driving‐shaft or cable used in dental engines; but it is also applicable to flexible shafts or cables of larger size such, for example, as those used in engineers shops for ‘drilling holes in boiler‐plates or other like heavy work’. The flexible shafts or cables ordinarily employed are not capable of being bent to and working at a curve of very short radius ….”

The first recorded true horizontal oil well was drilled near Texon, Texas, and was completed in 1929 (Popular Horizontal 1991). Another was drilled in 1944 in the Franklin Heavy Oil Field, Venango County, Pennsylvania, at a depth of 500 ft (13 m) (Yost et al. 1987). China also tried horizontal drilling as early as 1957, followed by the Soviet Union. Generally, however, little practical application occurred until the early 1980s, by which time the advent of improved downhole drilling motors and the invention of other necessary supporting equipment, materials, and technologies were attained. Notably, downhole telemetry equipment brought some kinds of applications within the imaginable realm of commercial viability. Tests, which indicated that commercial horizontal drilling success could be achieved in more than isolated instances, were carried out between 1980 and 1983 by the French firm Elf Aquitaine in four horizontal wells drilled in three European fields: the Lacq Superieur Oil Field (two wells) and the Castera‐Lou Oil Field, both located in southwestern France, and the Rospo Mare Oil Field, located offshore Italy in the Mediterranean Sea (US EIA 1993). In the latter instance, output was considerably enhanced. British Petroleum would subsequently commence early production well using horizontal drilling techniques in Alaska’s Prudhoe Bay Oil Field (Journal of Petroleum Technology 1990), in a successful effort to minimize unwanted water and gas intrusions into the Sadlerochit reservoir.

As of the early 1990s, domestic horizontal wells have been planned and completed in at least 57 counties or offshore areas located in or off 20 states (US EIA 1993). In the United States the focus has been almost entirely on crude oil applications. In 1990, worldwide, more than 1000 horizontal wells were drilled. Some 850 of them were targeted at Texas’ Upper Cretaceous Austin Chalk Formation alone. Less than 1% of the domestic horizontal wells drilled were completed for gas, as compared with 45.3% of all successful wells (oil plus gas) drilled. Of the 54.7% of all successful wells that were completed for oil, 6.2% were horizontal wells. With a focus on oil, market penetration of the new technology had a noticeable impact on the drilling market and on the production of crude oil in certain regions. For example, in mid‐August of 1990, crude oil production from horizontal wells in Texas had reached a rate of over 70 000 barrels per day. Horizontal drilling technology in conjunction with well stimulation techniques, notably hydraulic fracking, would solidly move into the arsenal of the oil and especially the gas industry since the early 1990s. By 2000, natural gas generation would grow faster than any other energy source, with the shale gas boom pushing prices to record lows. And then, for one month in spring of 2001, more natural gas was burned and used to generate electricity in the United States than by the burning of coal, for the first time ever.

During the 1970s, the term “massive frac” was coined to describe hydraulic fracturing operations of deeper, high temperature formations that used nearly 1 million gallons (3.8 million liters) of fluids, more than 3 million pounds (1361 metric tons) of sand, and a more diverse mix of additives. By the 1980s, better reporting of hydraulic fracturing fluids indicated that water was the most common treatment fluid type. Temperature‐sensitive gelling agents emerged, such as hydroxyethyl cellulose (HEC) polymer‐based gel and a secondary gel treated with glyoxal. These gels activated under high temperature and low to moderate pH once introduced in the formation. A similar gel‐based system using hydroxypropyl guar (HPG) also was found to work well at elevated pH. These gel bases were crosslinked with zirconium(IV) and titanium(IV) to create crosslinked guar fluids, which have better temperature stability than borate. Also during this era, 20/40 sand (425–850 μm) was used in 69% of hydraulic fracturing treatments and continued to be the dominant particle size throughout the 1990s and early 2000s.

2.5.2 The Carter Years and the Role of the Feds

Understanding the technological advances being made during the 1970s and 1980s deserves mention of the federal role and investment following federal price controls on natural gas that led to shortages in the 1970s. On 18 April 1977, US President Jimmy Carter (39th president from 1977 to 1981) went on television and declared that we were running out of domestic natural gas. The Carter Doctrine essentially declared that any interference with US oil interests in the Persian Gulf would be considered an attack on the vital interests of the United States.

The federal government in response to declining natural gas production invested in many supply alternatives, including the Eastern Gas Shales Project (EGSP) and the annual FERC‐approved research budget of the Gas Research Institute (GRI). GRI was funded by a tax on natural gas shipments from 1976 to 2000. The EGSP had two goals: evaluate the gas potential of Devonian and Mississippian shale basins and develop new drilling, stimulation, and recovery technologies. The Department of Energy (DOE) partnered with private gas companies to complete the first successful air‐drilled multi‐fracture horizontal well in shale in 1986. Microseismic imaging, an important input to both hydraulic fracturing in shale and offshore oil drilling, originated from coalbed research at Sandia National Laboratories.

The EGSP lasted from 1976 to 1992 and focused on extending and improving recoveries in known productive shale gas areas, particularly the greater Big Sandy Gas Field of Kentucky and West Virginia. Two technologies were applied that had been developed previously by industry for shale gas formations: MHF and horizontal drilling. In 1976 two engineers for the federally funded Morgantown Energy Research Center (MERC) patented an early technique for directional drilling in shale.

Tax credits and rules were also provided by the federal government, which benefited the industry in the 1980 Energy Act. Gas production from Devonian shales was exempted from federal price controls, and Section 29 tax credits were given for unconventional gas, including shale gas, from 1980 to 2000.

The work of GRI and EGSP increased gas production in the southern Appalachian Basin and the Michigan Basin. However, in the late 1990s, shale gas was still widely viewed as marginal to uneconomic without tax credits. With expiration of the tax credits, shale gas provided only 1.6% of US gas production in 2000. The EGSP had tested a wide range of stimulation methods, with DOE concluding that stimulation alone could not make the eastern gas shales economic. The USGS in 1995 noted that future production of gas from the eastern shales would depend on future improvements in technology. However, according to some analysts, the federal programs had planted the seeds of the coming shale gas boom.

George Mitchell is considered the “Father of the Shale Gas Boom.” Mitchell was a captain in the Army Corps of Engineers during WWII and went to Texas A&M University studying petroleum engineering with an emphasis on geology. Mitchell would subsequently form a wildcatting company and would over the years participate in ~10 000 wells and 200 oil and 350 gas discoveries. As chairman and CEO of Mitchell Energy & Development, a Fortune 500 company albeit not without trials and tribulations, he would merge with Devon Energy Corporation in January 2002. DOE subsidized Mitchell to drill his first horizontal wells, covering any costs beyond a typical vertical well, and the federal government provided unconventional gas tax credits. The Texas Bureau of Economic Geology created high‐resolution images of rock surfaces that yielded information about their porosity. Union Pacific Resources, the Fort Worth‐based exploration and production company, shared its superior method for hydraulic fracturing. DOE’s Sandia Labs contributed microseismic fracture mapping software that helped the operator make adjustments to improve the flow of gas.

Throughout the 1990s, GRI partnered with Mitchell Energy in applying a number of other technologies in the Barnett Shale. In 1991, Mitchell Energy completed the first horizontal frac in the Texas Barnett Shale. This project was subsidized by GRI and funded by a federal tax on gas pipelines. The first Barnett horizontal frac was not economically successful, as were Mitchell’s later experiments with horizontal wells. The Barnett Shale boom would however become highly successful with vertical wells. It was not until 2005 that horizontal wells being drilled in the Barnett outnumbered vertical wells.

Since 1981, Mitchell Energy began producing gas from the Barnett Shale of North Texas in 1981, but the results at first were uneconomic. The company persevered for years in experimenting with new techniques. Mitchell would abandon the foam frac method developed by EGSP in favor of nitrogen gel‐water fracs. Mitchell achieved the first highly economic fracture completion of the Barnett Shale in 1998 by using slickwater fracturing. According to the US Geological Survey, “It was not until development of the Barnett Shale play in the 1990s that a technique suitable for fracturing shales was developed.” Although Mitchell experimented with horizontal wells, early results were not successful, but the Barnett Shale boom became highly successful with vertical wells. 2005 was the first year that the majority of new Barnett wells drilled were horizontal; by 2008, 94% of the Barnett wells drilled were horizontal.

2.5.3 Recent Innovations in Fluids and Additives (2000–2010)

The period between 2000 and 2010 gave rise to notable changes in hydraulic fracturing treatment fluids and additives. Between 2007 and 2009, significant shale gas production began in states outside of Texas (Figure 2.17a). This increase in hydraulic fracturing treatments around 2008 is also consistent with the emergence of “slickwater” formulations (Figure 2.17b), as well as the increase in surfactant additives (Figure 2.17c) added to water to create the slickwater treatment fluid type. During this period, increased reporting of acid additives (Figure 2.17c), such as hydrochloric acid, indicates that they were used during initial hydraulic fracturing sequences either to restore permeability lost as a result of the drilling process or to initiate fracturing. Other additives include biocides such as glutaraldehyde, ozone, chlorine dioxide, ultraviolet light, chlorophenates, quaternary amines, and isothiazoline. This period would also see breakthroughs in the development of breakers, oxidizers, corrosion inhibitors, friction reducers, iron control formulations, oxygen scavengers, and scale inhibitors. Breakers include sodium chloride, oxidizers (such as ammonium, potassium, and sodium salts of peroxydisulfate), and (or) enzymes (such as hemicellulase). Corrosion inhibitors such as N,N‐dimethylformamide and friction reducers such as petroleum distillate or polyacrylamide appear. For iron control, 2‐hydroxy‐1,2,3‐propanetricarboxylic acid, citric acid, and acetic acid are used. Ammonium bisulfite would be used as an oxygen scavenger. Scale inhibitors included ethylene glycol, phosphonate, and polymers.

With slickwater fracturing of unconventional oil and gas reservoirs, finer proppant sizes as 30/50 and 40/70 also emerged. The rise in slickwater fluids also coincided with more than 58 000 directional and horizontal wells drilled between 2000 and 2010. Although most wells were vertically drilled, the proportion of newly drilled horizontal/directional wells rose from 6% of hydraulically fractured wells drilled in 2000 to 42% in 2010. About 73% of horizontal well treatments during this period were used to produce natural gas with the remainder used to produce oil resources.

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Suggested Reading

1. Adomites, P. (2011). The first frackers: shooting oil wells with nitroglycerin torpedoes. Oil‐Industry History 12 (1): 129–136.
2. API (1991). Joint Association Survey on 1990 Drilling Costs, 4–5. Washington, DC: Finance, Accounting and Statistics Department, American Petroleum Institute.
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4. HIS Energy (2011). Petroleum Information Data Model (PIDM) 2.5 Data Management System. Englewood, CO: HIS, Inc.
5. Lash, G. and Lash, E. (2014). Early history of the natural gas industry, Fredonia, New York. American Association of Petroleum Geologists Abstract, AAPG Annual Convention and Exhibition, Houston, TX (6–9 April).
6. Moore, S.D. (1991). Technology for the Coming Decade. Petroleum Engineer International, January 1991, p. 17.
7. Sherrard, D.W., Brice, B.W., and MacDonald, D.G. (1987). Application of Horizontal Wells at Prudhoe Bay. Journal of Petroleum Technology 39: 1417–1425.
8. Soeder, D.J. (2017). Unconventional: The Development of Natural Gas from the Marcellus Shale, Geological Society of America Special Paper, vol. 527. Boulder, CO: The Geological Society of America, 143 p.
9. Testa, S.M. (2015a). Historic Development of Fracturing and Hydraulic Fracturing, Part I: Explosives and Guns (1821–1940). Pacific Section American Association of Petroleum Geologists Newsletter, January–February 2015, pp. 10–17.
10. Testa, S.M. (2015b). Historic Development of Fracturing and Hydraulic Fracturing, Part II: The Birth of the Petroleum Engineer (1930s–1950s). Pacific Section American Association of Petroleum Geologists Newsletter, March–April 2015, pp. 12–15.
11. Testa, S.M. (2015c). Historic Development of Fracturing and Hydraulic Fracturing, Part III: Going Nuclear During Peak Oil (1960s). Pacific Section American Association of Petroleum Geologists Newsletter, May–June 2015.
12. Testa, S.M. (2015d). Historic Development of Fracturing and Hydraulic Fracturing, Part IV: The Rise of the Unconventionals (1990s‐Present). Pacific Section American Association of Petroleum Geologists Newsletter, September–October, 2015.
13. Testa, S.M. (2017). From the Battle of Fredericksburg to Promised Land – An Historical Perspective on Well Stimulation and Hydraulic Fracturing. Oil‐Industry History: Oil Industry History 17: 1–21.
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