Drilling Rigs

Early drillships were moored on location using 4 to 8 mooring lines leading to anchors or preset buoys. In 1963, the industry developed a design which permitted the drillship to rotate 360 degrees around an integral turret so it could always head into the seas thus reducing rolling motion.

The evolution of moored drillships follows:

YearVesselCompanyLocationRemarks
1956SubmarexCUSS GroupCaliforniaOver-the-side coring rig
1956Wn. ExplorerStandard OilCaliforniaCenter mounted coring rig
1956CUSS ICUSS GroupCaliforniaFull oilwell capability with center moon pool
1957D-1The Offshore Co.Gulf of Paria1st oil discovery from a floating vessel
1959NOLA 1
NOLA 2
NOLA 3
Zapata OffshoreGulf of MexicoConverted YF Barges with over-the-side cantilever rigs
1962Glomar IIGlobal Marine Inc.Cook Inlet1st new construction purpose-built drillship
1962C. P. BakerReading & BatesGulf of MexicoCatamaran formed by joining two YF hulls
1963Discoverer IThe Offshore Co.Gulf of Mexico1st center turret mooring system

After successful coring offshore California in the 1950’s using spread mooring systems, the National Science Foundation (NSF) needed a stationkeeping system for deeper waters.  In March 1961 the converted 3,400 LT drilling vessel Global Marine CUSS 1 recovered 28 geological cores from 5 holes in 11,700 ft. water depth using manual controlled steerable thrusters.  Although the test was successful it showed that manual thruster control was very difficult.  Concurrently Shell Oil Co. decided to build the 400 LT Eureka with two 200 Hp steerable thrusters with automatic lateral, longitudinal and heading resulting in successfully retrieved cores in up to 3,600 ft water depths in March 1961.  In late 1967 Scripps Institution of Oceanography, sponsored by the NSF and other countries, accepted an offer from Global Marine to construct a 10,000 LT coring vessel (The Glomar Challenger) using digital computers.   The vessel started operation in 1968 and cored throughout the world in up to 23,000 ft of water depth, contributing to the discovery of Global Tectonics.  In 1971, Shell Oil and SEDCO put the newly constructed SEDCO 445 into operation as the first DP drilling vessel which used subsea BOPs and a drilling riser.  This was closely followed by the IHC Holland DP vessel design and the first DP semi SEDCO 709. 

These forerunners have led the industry to today’s DP positioned drilling, production, construction and pipe lay barges that can operate in over 10,000 ft. water depths.

Recognizing the pioneering efforts of the following individuals and organizations that contributed to this technology:

Willard Bascom, Bill Bates, Ron Dozier, John Graham, Dillard Hammett, George Lagers,     Howard Shatto, Tom Stockton, Hank Van Calcar, Duke Zinkgraf, Baylor Company (now National Oilwell Varco), CFP (now TOTAL), General Motors, Global Marine (now Transocean), IHC Holland (now GustoMSC), Honeywell (now Nautronix), National Science Foundation, SEDCO (now Transocean) and Shell Oil Co.

Offshore Rig 51 was the first self-elevating drilling unit. It went into service in 1954. The Offshore Company was developed as a joint venture with Southern Production (now SONAT), J. Ray McDermott and DeLong. Based on the DeLong jacking system the rig had 10 legs, each 6 ft in diameter and 160 ft long, with large spud cans to limit penetration into the seafloor. By means of a jacking and holding mechanism, the barge pulled itself out of the water, safely above the waves.

Mr. Gus was a Bethlehem design, self elevating unit and was built in 1954 for C. G. Glasscock Drilling Co. intended for 100 ft water depth operations. The forerunner of today’s fleet of jackups was the Scorpion. Designed by R. G. Le Tourneau and built by the Le Tourneau Company in 1956, it was a triangular platform with 3 trussed legs. Each leg had a full length gear rack to engage the pinions of the elevating mechanism. Pinions were driven by powerful electric motors equipped with electromagnetic brakes. The Zapata Offshore Co., who had the foresight to purchase this innovative jackup design, was headed by future US President George Bush.

Recognizing the pioneering efforts of the following people and companies who contributed to the development of this technology:

George H. W. Bush, Colonel Leon B. DeLong, Charles G. “Mr. Gus” Glassock, Robert G. Le Tourneau, Ralph Thomas “J. Ray” McDermott, F. “Tim” Pease, James E. Steele, James C. “Jimmy” Storm, Bethlehem Steel, Le Tourneau Inc., J. Ray McDermott Co., The Offshore Co. (Transocean Inc.), Zapata Offshore Co. (Diamond Offshore)

Offshore rigs are vessels unlike any the world has ever known. To be able to build these behemoths and make them seaworthy requires unusual vision, determination and ingenuity. A few shipyards rose to the challenge. Alexander Shipyard, of New Orleans, built the first self-contained, mobile offshore drilling unit (MODU), the Breton Rig 20 in 1949, following an idea developed by John T. Hayward.  

Requiring considerable coordination between the shipbuilders and the drilling contractors, various designs were built in yards along the Gulf Coast. However, the work required the shipyards to make considerable modifications to their engineering and construction practices. Only a few were successful. By 1972, six Gulf Coast yards, Alexander and Avondale, of New Orleans, LA; Bethlehem, of Beaumont, TX; Ingalls, in Pascagoula, MS; LeTourneau, of Vicksburg, MS; and Levingston, in Orange, TX, had built a total of 104 MODUs, a remarkable achievement. Bethlehem developed a unique jackup design that includes our own Ocean Star Offshore Drilling Rig & Museum. Letourneau is still producing jackup rigs of its own design today. 

Two Singapore shipyards, Keppel FELS and PPL, started building offshore rigs in the early 70s. Today, they have emerged as modern pioneers, leaders in researching and designing rigs for deeper waters and severe operational environments.

Recognizing the pioneering efforts of the following individuals and companies who contributed to the development of this technology:  

Alexander Shipyard (now Bollinger Gulf Repair), Avondale Shipyard (now Northrup Grumman Ship Systems), Bethlehem Shipyard, Ingalls Shipbuilding (now Northrup Grumman Ship Systems), Keppel Offshore & Marine, LeTourneau Inc. (now LeTourneau Technologies, Inc.), Levingston Shipbuilding Company, PPL Shipyard Pte Ltd.

Deepwater drilling dictates that operations be carried out from a floating vessel. Drillships heave, pitch and yaw with each passing wave, and the industry needed more stable drilling platforms. A semi submersible obtains its buoyancy from ballasted, watertight, pontoons located below the ocean surface and wave action. The operating deck is located above the tops of the passing waves. Structural columns connect the pontoons and operating deck. When the rig moves its location, the pontoons are de-ballasted so that the rig can float on the ocean surface.

In 1961, Shell Oil successfully converted an existing submersible rig into the first semi submersible drilling unit for operation in the Gulf of Mexico. The industry quickly accepted the semi concept and the fleet increased rapidly to 30 units by 1972. At present, there are about 160 semi submersibles in service. First generation semis are generally limited to water depths of less than 600 feet, and second generation are usually intended for water depths up to 1000 feet. Most of these early semis have been retired.

YearRig NameFeaturesDesignerNo. Built
1961Bluewater IFirst semi submersible, converted from existing 4 column submersibleShell Oil1
1963Ocean DrillerFirst new build; 3 col. Vee shaped structureODECO2
1965Sedco 1353 footed columns; arranged in a triangular shapeFriede & Goldman12
1969Pentagone 815 footed columns arranged in pentagon shapeNeptune11
1971Ocean ProspectorFirst self-propelled, 12 columns; 2 main tubular hulls; Ocean Victory classODECO11
1973Sedco 700Twin pontoon hulls; 8 columns
thruster propulsion
Earl & Wright15
1973Western PacesetterTwin pontoon hulls; 6 columns
design licensed to all
Friede & Goldman39
1974Deap Sea DrillerTwin pontoon hulls, 8 columns (known as Aker H-3 Design)Aker Mek Verksted29

Recognizing the pioneering efforts of the following people and companies who contributed to the development of this technology:

Bruce Collipp, Jerome Goldman, Alden J. “Doc” Laborde, Bill Martinovich, Fred Olsen, Andre Rey-Grange, Aker Mek Verksted, Earl & Wright, a Sedco Company (Transocean Inc.), Friede & Goldman (Friede Goldman Halter), Neptune (Transocean Inc.), ODECO (Diamond Offshore Drilling), Shell

In 1928 Louis Giliasso filed a patent for a submersible drilling barge based on his experiences in Lake Maracaibo, Venezuela. The first submersible went to work for The Texas Company on November 17, 1933 at State-Pelto No. 10, Louisiana. It was equipped to drill to 6,000 ft and operate in 15 ft of water. John Hayward saw the opportunity to combine a barge and a piled platform, so that the rig’s working decks were above the water and only the columns connecting to the submerged barge were exposed to wave forces. He developed a method for ballasting the barge to the seafloor without it becoming unstable and overturning. The Breton Rig 20 was conceived by Hayward and built for Barnsdall Oil & Refining Co. getting into operation in 1949. It drilled 19 wells before being sold to Kerr-McGee in 1950. An improved version of the submersible was developed by Alden J. “Doc” Laborde, a young Naval engineer, who founded Ocean Drilling and Exploration Co. (ODECO) in 1953. The rig was built in Alexander Shipyard in New Orleans, and was named Mr. Charlie after Charles Murphy, President of Murphy Oil. Its first well was drilled for Shell in the East Bay Field, near the mouth of the Mississippi in 1954. Water would be pumped into the barge to sink it. When resting on the bottom, it formed a stable platform from which to drill. When the drilling was finished, the submersible could be refloated and towed to the next location. Mr. Charlie is now a museum in Morgan City, Louisiana. Recognizing the pioneering efforts of the following people and companies who contributed to the development of this technology:

Emile J. Brinkmann, Jr., Louis Giliasso, Jerome L. Goldman, John Hayward, Alden J. “Doc” Laborde, Charles Murphy, Jr., Paul Wolff Barnsdall Oil & Refining Co. (Oryx Energy), Kerr-McGee, Murphy Oil, ODECO (Diamond Offshore), Shell, The Texas Company (ChevronTexaco, now Chevron)

Initial offshore drilling was carried out using small, piled platforms. The equipment, supplies, and personnel were housed on converted LSTs (Landing Ship Tanks) and Y-F (Yard-Fighter) barges, which after 1947, were surplus from World War II. These vessels were known as “tenders” (named after the coal-carrying tenders coupled to steam train engines). R.S. Kerr pioneered the use of tender rigs and is chronicled as the first to strike oil out of sight of land in 1947 in Ship Shoal Block 32. Phillips Petroleum Co. (50%) and Stanolind Oil and Gas Co. (37.5%) were partners in the well. Kerr-McGee acted as driller and operator. The tender was the Frank Phillips. The prototype of the Kerr-McGee tender approach was introduced in Lake Maracaibo, Venezuela, in 1934 and prior to that similar setups had been used in the marshy areas of the Gulf coast. Oil companies bought LSTs and refitted them for offshore purposes after this first discovery. For the next several years, 90% of the offshore wells were drilled from tender-platform combinations.

The narrow gangplank connecting the heaving tender with the stationary platform was called the “widow-maker” with good reason.

Recognizing the pioneering efforts of the following people and companies who contributed to the development of this technology:

Robert S. Kerr, Sr., Frank Phillips Kerr-McGee, Phillips Petroleum, Stanolind (BP)

The industry has applied its considerable ingenuity and determination to protect the environment so that oil and gas wells can be safely constructed offshore. An example of this effort is the development of the Mobile Bay area, offshore Alabama. Zero-discharge means exactly what it says—nothing will be allowed to fall into the sea after it has touched the rig. This includes indigenous rainwater. Also included in the rules are 3 categories of solid discharge—industrial waste, sanitary waste and wellbore cuttings—and 7 categories of liquid discharge. Besides weather runoff, these include cooling water, sanitary water, waste oil, drilling fluids, and machinery deck and mud processing drainage. 

Meeting these exacting requirements were rigs contracted by the developer, ExxonMobil. These included the Rowan 4, Penrod 65 (now Noble Bill Jennings), GlobalSantaFe High Island IV, Penrod Portal 202 (now Noble Joe Alford), Chiles Seabee (now Noble Tom Jobe) and the Penrod Prober 94 (now Ensco 94).  It should be noted that in addition to operating under zero-discharge rules, the rigs had to contend with dangerous hydrogen-sulfide gas, necessitating stringent safety regulations for personnel and equipment. 

The State of Alabama should be justifiably proud of its role in developing the zero-discharge regulations, and the success it has achieved in safely producing hydrocarbons from beneath Mobile Bay. ExxonMobil is to be commended for its role in proving that the petroleum industry can safely drill and produce offshore while protecting the environment. 

Recognizing the pioneering efforts of the following individuals and companies who contributed to the development of this technology: 

The State of Alabama, Chiles Drilling (now Noble Corporation), ExxonMobil, Global Marine (now Transocean), Penrod, Rowan Companies, Transworld Drilling (now Noble Corporation)

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