Vol. No. 9

September 1999

Frontiers of Technology

Drilling Technology

The Key to Successful Exploration and Production

Using steam-powered cable-tool rigs that pounded the Earth with fishtail bits until it gave up its oil, turn-of-the-century drillers managed to find oil with surprising frequency. The drilling technology wasn’t much by today’s standards, but it worked on the shallow prospects of Pennsylvania and Ohio during the late 1800s and early 1900s.

However, greater drilling challenges occurred when oilmen expanded their efforts to Texas, where the oil lay encased in deeper pay zones. Here, drilling targets could not be reached using standard cable-tool methods. Instead, rotary rigs were brought in to drill the deeper plays. These rigs represented the latest technology, and they quickly became the preferred method for drilling.

The Rotary Rig

Between 1915 and 1928, rotary rigs slowly began to replace existing cable-tool rigs. The invention of the rotary-drilling rig made cable-tool rigs obsolete, for all intents and purposes. The rigs, named for the rotary table through which drillpipe is inserted and rotated, could make deeper holes because they used a bit that drilled rather than pulverized the rock formation.

Also, rotary rigs eliminated the laborious, time-consuming bailing process used by cable-tool rigs to remove rock cuttings from the hole. Instead, drilling fluid was circulated down the drillpipe, through the bit, and up to the surface. As a result, rock cuttings created by the bit were lifted by the fluid and carried to the surface for disposal.

The new rigs created a need for experienced drillers who knew how to use them. Experienced cable-tool drillers had to learn quickly how to operate the new rotary rigs so they could make the transition to them. Some did, and some didn’t. Those who made the transition stayed employed. Those who didn’t became unemployed. One of those drillers who successfully made the transition was John Goddard, a cable-tool driller who eventually became one of the original stockholders of Humble Oil and Refining Co.

Because of his reputation for drilling successes in the oil fields of Ohio, Goddard was brought to Texas to drill with the rotary rig. When he got to Texas, Goddard was careful not to mention to anyone that he had never even seen one of the new rotary rigs. Instead, he quickly and quietly learned how to run the new equipment and, over the years, contributed greatly to Humble Oil’s growth to an oil giant. From 1928 to 1934, some of the largest oil fields of all time were discovered, and drilling was highly competitive. There were insistent demands for equipment that could drill and complete wells in minimum time periods. During this period, heavy and more powerful rigs were developed.

After 1934, rates of penetration with rotary rigs increased more rapidly than in any period, before or since. And the use of steam-powered engines gave way to the internal-combustion engine as the most important prime mover. During World War II, further development and refinement of rotary rigs was put on hold since most of the nation’s resources were largely diverted to the manufacture of war implements. However, with the war’s end in the mid-1940s, an increase in demand for petroleum products led to a rise in oil- and gas-well drilling. Practically all of the drilling equipment that was available was either obsolete or worn out, which led to the development of new and better drilling equipment, especially rigs. Today’s modern rotary-drilling rigs are powered by diesel and diesel-electric prime movers.¹

Rolling Bits

Another milestone was the development of bits for use on rotary-drilling rigs. In 1908, Howard Hughes Sr., a wildcatter and speculator in Texas oil leases, turned his ingenuity and hobby of tinkering with mechanical devices into good fortune when he invented the rolling bit (later called the roller-cone or rock bit).

In the period following the turn of the century, existing drilling technology was unable to penetrate the thick rock of southwest Texas. Until 1910 or 1911, the only drilling bits available for rotary rigs were the fishtail, the diamond point (mainly for sidetracking), and the circular-toothed bit—all of which limited the rigs to soft formations. Oilmen could extract only the oil that lay just beneath the surface. Frustrated, they were forced to ignore the vast resources they knew were locked in the deeper formations.

Fortunately for them, Hughes had an idea for a bit that used 166 cutting edges arrayed on the surface of each of two metal cones mounted opposite each other to tear away the hard-rock formations. He also solved the problem of how to cool and lubricate the bit in the high temperature produced by the friction of the metal and rock contact.

Hughes, along with his partner Walter B. Sharp, formed the Sharp-Hughes Tool Co. and produced a model of his new bit. Rather than sell his bits to oil drillers, Hughes and Sharp opted to lease the bits on a job basis, charging U.S. $30,000 per well. With no competitors to duplicate their drilling technology, they soon garnered the lion’s share of the market. Flush with their success, the partners built a factory on 70 acres east of downtown Houston, where they turned out the roller-cone bits that quickly revolutionized the drilling
process.²

About the same time Hughes developed his bit, Granville A. Humason of Shreveport, Louisiana, patented the first cross-roller rock bit, the forerunner of the Reed cross-roller bit.³ That bit, built in 1913, used two rolling cutters that were placed in the bit face in a “+” shape. This bit, screwed onto the end of the rotating drill pipe, cut the rock formation as it turned, enabling the rig to penetrate the formation without destroying the bit’s cutting surfaces.

The rotary rig, rolling bit, and cross-roller rock bit were pioneering inventions that paved the way for the development of a great many other devices that improved drilling processes and techniques.

Drill Collars

One of the earliest problems drillers encountered in rotary drilling was that of keeping their boreholes straight. The deeper drillers went, the more the boreholes deviated from vertical. It was common practice at that time to use only large drill pipe and all available weight (weight indicators were not yet available). Often, deviation didn’t matter because the targeted formation was eventually reached and the well declared a success. In fact, most drillers were never aware of their deviation from vertical.

For the most part, the entire petroleum industry was unaware of the problem of hole deviation until the Seminole, Oklahoma, boom of the mid-1920s. Town lot spacing was the primary factor contributing to the experiences of the industry. There are actual recorded incidents of two rigs drilling the same hole, offset wells drilling into each other, drillers wandering into producing wells, and wells in the geometric center of the structure coming in low or missing the field completely.

These experiences led to the development of the drill collar for weight and rigidity and the use of stabilizers at various points in the string to control deviation and to provide rigidity. This helped control unintentional deviation, but a total understanding of the forces associated with borehole deviation didn’t occur until Arthur Lubinski performed his study of the problem in the 1950s. His successful studies led to the development of directional drilling, a method used extensively by the industry to cost-effectively drill and complete multiple wells from a single location.⁴

Well Control

With continued increases in drilling depth came increasingly higher formation pressures that had to be controlled during the drilling process. If released by the penetration of the formation by the drill bit, these enormous pressures could spit drillpipe out of the hole, unleashing raging inferno-like fires that would instantly destroy the drilling rig. Such a catastrophic event could delay drilling operations for days or even months, until the fires could be extinguished. This made the development of some sort of blowout-prevention device a priority among those engaged in oilwell drilling.

In the 1920s, driller James Abercrombie sought out Harry Cameron, a machine-shop operator, to design and build a device that would prevent catastrophic well blowouts during drilling operations. Following a period of experimentation, Abercrombie and Cameron designed and manufactured the first successful blowout preventer (BOP). The preventer was capable of containing formation pressures of 2,000 to 3,000 psi in 8-in. boreholes. It did not take long for the revolutionary device to dominate the industry.

The need for control greatly expanded when drilling began on the U.S. gulf coast and in the Gulf of Mexico. Containing normally pressured formations is relatively simple when compared with containing and controlling highly pressurized geopressured zones. Today, offshore BOP stacks that can hold pressures of 15,000 psi in 183/4-in boreholes are available, if needed.

Louis Records also made great contributions in well-control equipment. His company, Drilling Well Control, offered well-control expertise and a monitoring service. Records was one of the first to truly understand the mechanics required to circulate oil and gas from a well without allowing additional gas or oil to enter the wellbore. C.C. Brown, another industry drilling pioneer, invented the wellhead packoff, a device that allowed a well to be completed without letting it flow freely during the operation.

Drilling Fluids

In the earliest years, the drilling fluid used by the cable-tool rigs was probably water. It was used to soften the earth and make it more pliable for drill-bit penetration. With the advent of rotary rigs and roller-cone bits, more elaborate drilling fluids, called “muds,” were introduced into the borehole to cool and lubricate the bit, circulate the rock cuttings from the bottom of the hole to the surface, and hydrostatically balance the drilling-fluid column.

These drilling muds were originally “natural” and were formed from the formation drilled or from native material. Later, they were “weighted up” using barite or similar products to counter the higher pressures that were experienced as formation depths increased. This helped prevent the dreaded blowouts. Initially, mud materials were low-cost waste products from other industries, but as the drilling goals required drilling deeper, hotter holes and higher fluid densities, the industry began developing specialty chemical products designed for specific purposes.

Over the years, drilling-fluid challenges and the resulting solutions have moved the drilling-fluids industry from the use of fluids costing very little to complex oil- and water-based materials that typically cost U.S. $300 to $400/bbl.

Well Cementing

With drilling operations routinely penetrating multiple rock and sediment layers that contained water, oil and gas, it became necessary to install steel casing to isolate these layers from one another and from the wellbore. The casing was installed in a variety of sizes. Large-diameter pipe was installed near the surface, and as the depth increased, the pipe diameter became progressively smaller.

Originally, the formation was “mudded off,” and extra-thick drilling mud was left behind each string of casing in an effort to minimize fluid communication. Mechanical devices also were used on occasion. However, this was ineffective and soon led to the use of cement. Casing had been cemented in cable-tool-drilled wells prior to 1900.

Early cementing jobs were very rudimentary. Cement was mixed on location by hand and installed with a dump bailer. After depositing the cement, the casing, which had been held several feet off bottom, was lowered into the cement so it would remain behind the pipe after hardening to shut off the water from above. Later, tubing was used to convey the cement with pumps. But, in 1921, Erle P. Halliburton put an end to these laborious cementing methods and, in the process, revolutionized well cementing.

Halliburton started the Halliburton Oil Well Cementing Company in 1919 in his one-room wood-frame home in Wilson, Oklahoma. Two years later, Halliburton perfected his Cement Jet Mixer, an on-the-fly mixing machine that eliminated the hand mixing of cement at the wellsite. This invention set the stage for Halliburton’s domination of the business of well-casing cementing.

Then, in 1924, Halliburton convinced seven of his customers --- all large oil companies --- to invest in Howco. The company went public, and Halliburton became the company’s first President and Chief Executive Officer.

“We intend to build up and maintain a complete organization,” he stated when asked about his intentions in those first days after going public. “We will cover all phases of oil well cementing service. We will maintain an aggressive and sustained program of research. We shall give uniform quality and service. We’ll get there somehow, regardless of location,” he continued.⁵ This focus on service and technology research has kept the company in the forefront of the oil and gas services industry, where it remains a leader today.

Formation-Evaluation Logging

The earliest drillers were severely limited in their opportunities to evaluate potential reservoir rocks without testing to see what they produced. Wells were drilled without any possible means of measuring the inclination angle of the borehole, which, as we learned more, turned out to be quite high. The whole series of developments in that area first produced crude inclination indicators by lowering a glass tube with an etching fluid inside and mechanical instruments that measured the inclination angle. This eventually led to tools that could be used to determine the azimuth of the hole and finally offer the ability to calculate the position of the bottom of the hole with fair accuracy.

Formation-evaluation efforts began with the art of mud logging, in which samples of the cuttings were analyzed to determine the formations that were being drilled. Drillers also began recording the penetration rate vs. depth to define more precisely where formation changes occurred.

In 1911, electrical well logging originated with two brothers, Conrad and Marcel Schlumberger. The science of geophysics was new, and the use of magnetic or gravimetric methods of exploring the internal structure of the Earth was just beginning. Their electric logs extended the electrical prospecting technique from the surface into the oil well.

The technique was actually invented by Conrad Schlumberger. As a physics teacher at Ecole des Mines, Conrad had an interest in the Earth sciences, particularly those involving prospecting for metal-ore deposits. He believed that among the physical properties of metal ores, their electrical conductivity could be used to distinguish them from their less-conductive surroundings.

In 1912, he used very basic equipment to record his first map of equipotential curves in a field near Caen, France. The plot of curves derived from his surveys not only confirmed the method’s ability to detect metal ores but also revealed features of the subsurface structure. This information led to an ability to locate subsurface structures that could form traps for minerals.

To understand the measurements made at the surface better, Conrad and Marcel knew they had to incorporate resistivity information from deeper formations. In 1927, in a 1,640-ft (500-m) well in France’s Pechelbronn field, Conrad’s son-in-law, Henri Doll, an experimental physicist, successfully produced the world’s first “electric log” using successive resistivity readings to create a resistivity curve.

Four years later, in 1931, the discovery of a “spontaneous potential” produced naturally between the borehole mud and formation water in permeable beds introduced a new basic measurement. When recorded simultaneously with the resistivity curve, permeable oil-bearing beds could be differentiated from impermeable nonproducing beds. Thus, electrical well logging was born.⁶

Blowout Control

Most drillers believed that, if you drilled hard enough and long enough, a blowout was inevitable. And, for the most part, they were right. Blowouts did occur. Equipment failures, improper technique, and bad luck created blowouts that needed to be handled quickly, safely, and properly. This meant a call to the wild-well-control experts. A special breed of firefighter, the well-control experts took on the raging inferno and brought it under control using a series of steps that deprived the fire of oxygen, allowing it to be safely capped.

The first heroes of this parade were Myron Kinley and Red Adair. Whenever anyone had a blowout, the solution was to call Kinley or Adair to control, then cap, the blowout. While their skills, capabilities, and performance allowed them to handle most any blowout in a workmanlike manner, the nature of their work and the public’s perception of it made them legendary. This, in turn, allowed them to become very effective public relations men for their clients.

Their experiences also led to the development of a number of active and passive firefighting devices for offshore rigs. Since firefighting equipment was not readily available at offshore drilling sites, technology was developed that could be permanently mounted on the offshore drilling rig. In the event of a blowout, it helped cool the tremendous heat generated by the blowout, allowing workers to safely evacuate the rig. It also enabled the firefighting team to place cooling water where they needed it when they arrived on the scene to cap the well.

Wells Get Deeper

The development of technology for controlling blowouts enabled the drilling of deeper wells, but it was not until 1938 that the drill passed 15,000 ft, a record that stood until 1947. The 20,000-ft barrier was penetrated two years later in 1949, a record that held until Phillips Petroleum drilled the University EE-1 well to 25,340 ft in 1958 in west Texas.⁷

The 1960s and 1970s saw wells attain ultradeep status. Improved metallurgy and techniques for handling higher temperatures and pressures and corrosive atmospheres made ultradeep wells attainable and less formidable than before. The 30,000-ft barrier was broken in 1974 by the 31,441-ft Bertha Rogers No. 1 in Oklahoma’s Anadarko basin. But British Petroleum’s Wytch Farm M11 well garnered the depth record at 34,967 ft when it was drilled and completed in 1998.

Offshore Drilling

Some of the most significant technical achievements in the evolution of drilling technology have occurred in the offshore drilling arena.

When Kerr-McGee Corp. drilled the first offshore well out of sight of land in 1947 to officially begin today’s offshore industry, it wasn’t the first well drilled offshore. According to oil historian J.E. Brantly in his book History of Oil Well Drilling, operators actually took their first steps in drilling submarine as early as 1897 when a well was drilled from a wharf in California’s Summerland field.

Eight years later, in 1905, Unocal Corp. drilled an offshore well near Houston, and others followed by drilling in swamps and transition zones during the next 20 years. In the 1940s, operators took more definitive steps by mounting land rigs on piers jutting several hundred feet into lakes, bays and coastal waters. However, Kerr-McGee’s Kermac 16 well drilled in 20 ft of water from a platform 43 miles southwest of Morgan City, Louisiana, severed the industry’s umbilical cord with land.⁸ The early 1950s saw a major expansion beyond the Gulf of Mexico to the California coast and to the bountiful offshore basins of Brazil and Venezuela’s Lake Maracaibo. Another big advance occurred in the Gulf of Mexico in 1954 with the introduction of the moveable, submersible offshore drilling barge. The portability of the submersible drilling barge produced a major increase in the attractiveness of drilling offshore, but brought a new set of challenges to drillers.

The biggest challenge involved finding a solution to drilling from a floating barge while using conventional rigs, casing heads, and BOP equipment. Needless to say, the motions of the barge and rig derrick made it a daunting experience. One of the earliest solutions to rig movement was the submersible drilling barge, the Mr. Charlie. The rig was the brainchild of A.J. LaBorde, a marine superintendent for Kerr-McGee Oil Industries in Morgan City, Louisiana. In this capacity he had a front row seat for observing the problems of offshore oil drillers in varying conditions of water depth, wind, and wave action. Knowing their problems, he designed a submersible drilling barge and suggested to his employer, Kerr-McGee, that they build the barge. After considering the proposal, they declined.

Having been rejected by Kerr-McGee, LaBorde promptly resigned. Shortly thereafter, he formed the Ocean Drilling & Exploration Co., or Odeco, with John Hayward and Charles Murphy Jr. of Murphy Oil Co. Hayward possessed a patent on submersible-barge methods, and Murphy was looking for innovative technology that would let his small company compete with bigger companies drilling offshore. Together they decided to name their new rig the Mr. Charlie in honor of Murphy’s father.

On June 15, 1954, its builder, J. Ray McDermott Co.,turned over the completed drilling barge to Odeco. It wasn’t long before it set sail for its first job. Since no one had ever built a submersible drilling barge before, skeptics anxiously crowded the site of its first job to see if it would work. For LaBorde, there was no privacy if a mishap or problem occurred. However, to his relief—and to the surprise of the skeptics—the barge worked perfectly. During the next 32 years, the rig went on to drill hundreds of wells in the Gulf of Mexico. Mr. Charlie retired from service in 1986 when drilling activity pushed into deeper waters beyond its capabilities.⁹

The Future

Without a doubt, drilling technology will continue to progress toward more cost efficiency and speed. That is what it has always done because operators demand it. Therefore, manufacturers and service suppliers will continue to hone their technology to provide more efficient equipment throughout every aspect of the drilling process. According to George Boyadjieff of Varco Intl., much of the technological gain in the future will be in the information area. “The Internet will come to the drilling industry. Rigs will be connected just as offices are connected now. Real-time well site data will be provided routinely to offices of drilling engineers, operations managers, geologists, asset managers, reservoir engineers, and the like,” says Boyadjieff in an article commemorating the 50th anniversary of the offshore industry. “Also, I believe we’ll see underbalanced drilling become as common as horizontal and multilateral drilling. It’s not just for reservoirs.”¹⁰

References

Brantley, J.E.: “Hydraulic Rotary-Drilling System,” History of Petroleum Engineering, American Petroleum Inst., New York City (1961) chap. 6, 325.
http://users.erols.com/dbarrese/dad.html. 08/99.
Brantley, J.E.: “Hydraulic Rotary-Drilling System,” History of Petroleum Engineering, American Petroleum Inst., New York City (1961) chap. 6, 327.
Grace, R.D.: “The Problem of Deviation and Dog Legging in Rotary Boreholes,” Drilling Practices Manual, The Petroleum Publishing Co., Tulsa, OK (1974) chap. 13, 327.
http://www.halliburton.com/ .08/99
http://www.slb.com/. 08/99
“Four Decades of Giant Technical Strides,” Pet. Eng. Intl., Petroleum Engineer Publishing Co., Dallas (Oct. 1969) 53.
www.rigmuseum.com/history/index.html. 08/99.
50 Years of Offshore Oil & Gas Development, Hart Publications Inc., Houston (1997) 8.
“Varco Aims for Drilling Efficiency Gains,” 50 Years of Offshore Oil and Gas Development, Hart Publications Inc., Houston(1997) 105.