OFFSHORE DRILLING

Unique Marine Craft Moves Rigs with Speed and Economy at Lake Maracaibo

ROBERT E. KUNZ'* CREOLE PETROLEUM CORP. Downloaded from http://onepetro.org/JPT/article-pdf/14/03/228/2213322/spe-148-pa.pdf by guest on 27 September 2021 MEMBER A/ME TlA JUANA, VENEZUELA

Abstract in the development of a "U"-shaped, self-propelled craft which can maneuver around the well platform, pick up During the past three years, Creole Petroleum Corp. the rig-derrick package, move to the next location, and has used a highly specialized marine craft to move unitized then place the unit on the new foundation (~~C Figs. 1 and drilling rigs in its Lake Maracaibo, Venezuela, oilfield lA). Even though over one and three-quarter million operations. This paper describes the development, con­ dollars have been investen in the rigmover and its as­ struction, operation and economics of Creole's "floating sociated substructures, the savings realized through the fork-lift". The marine rigmover has proven to be a prac­ use of this equipment paid out the investment in Nov., tical and economical device, and it could be used in any 1961. large-scale oilfield development program in deep inland or sheltered ocean waters. Development History Introduction As early as 1951, Creole was making over-water rig The great majority of Creole Petroleum's concessions moves similar in principle to those made by the rigmover. in Western Venezuela lie beneath the waters of the north­ The original "straddle barges" unit was designed for use east quadrant of Lake Maracaibo. Lake Maracaibo is a in the Pedernales field, located in the tidal channel area of large, pear-shaped, fresh-water lake about 100-miles long the Orinoco river delta in Eastern Venezuela. It consisted and 60-miles wide with a maximum water depth of 125 ft of two barges supporting a one-piece substructure com­ and an over-all average depth of about 40 ft. plete with draw-works, engines and derrick. The drilling unit was placed by straddling the new pile foundation All of the company's lake wells have been drilled from with the two barges and then lowering the rig by con­ permanent, concrete-pile platforms. These rlatforms sup­ trolled flooding of the barges. The moves were also timed port the rig substructure, a standard-type de" rick, the draw­ to take advantage of the tidal differences in water level. works and the drill string. Lateral-sway bracing is the only Mud pumps and pipe racks were aboard a barge tender. connection between the casing strings and the well plat­ form. Mud pumps, pipe racks, auxillary equipment and materials storage are located on an anchored barge-tender. Almost all of Creole's earlier wells in the lake were equipped with a standard derrick which was left in place on completion of the well in order to be utilized in future repair jobs. It was felt that the capital outlay for many derricks was less than the expense required to erect and dismantle a derrick for each repair job during the life of a well. In 1955, Creole's management authorized a study of the derrick and rig-moving problem to determine if there was a faster, more economical method of handling the job. Creole's goal was to replace the old method of rig moving-that is, piece ~meal movement of the rig-with a more efficient unitized method. This goal was attained

Original manuscript received in Society of Petroleum Engineers office Aug. 17, 1961. Rev'sed manuscript r eceived Jan. 8, 1962. Paper presented at 36th Annual Fall Meeting of SPE, Oct. 8-11, 1962, in Dallas. ' Left Creole Petroleum Corp. in Janua ry of this year to join Global Marine Exploration Co. in Los Angeles, Calif. Fig. i-Stern view of rigmover.

228 JOURNAL OF PETROLEUM TECHNOLOGY At the completion of a well, the flooded barges were The yoke is a rigid truss which is joined to the pontoons repositioned under the outriggers on the substructure and by a supporting leg at each of its four corners. The yoke pumped out, thus raising the drilling unit. is raised and lowered by means of hydraulic pistons operat- This unit continued operating in Pedernales until 1954, at which time it was transferred to Lake Maracaibo. It was used to drill deep exploratory wells until 1959, when it was idled. Although the "straddle barges" method of rig moving was rather slow, it was faster than dismantling, moving the rig piece-meal and then re-rigging. In 1955, the company management felt that, in view of the anticipated large increase in drilling activity on Lake Maracaibo, a study should be made of an improved method of transporting unitized drilling packages. A. U. S. firm of consulting engineers was commissioned to make an investigation into the various means of effecting Creole's Lake Maracaibo rig moves. Sixty-seven proposals were reviewed before selecting the design for the rigmover. Final blueprints

were completed in the spring of 1957, and the construction Downloaded from http://onepetro.org/JPT/article-pdf/14/03/228/2213322/spe-148-pa.pdf by guest on 27 September 2021 contract for the mover and six substructures was awarded to a Gulf Coast ship-building and steel-fabricating firm. After a year of construction and testing in the U. S., the rigmover was towed to Venezuela. The first rig move was made on July 29, 1958, but testing and modification of the rigmover and sub-bases continued in Venezuela for another year. It was not considered fully operational until July 1, 1959.

Description The Creole rigmover is essentially a marine fork-lift. It is composed of two major parts-( 1) a pair of flotation pontoons, and (2) a "U"-shaped superstructure or "yoke" Fig. 2-Bow view of rigmover as it maneu"er around well which connects the two pontoons (Figs. 1,2 and 3). The platform just before pickin·g up light package. cylindrical pontoons are each 115-ft long and I5-ft in diameter with hemispherical ends. The beam of the craft is 80 ft, its unloaded draft is 6 ft 2 in., and its fully loaded draft is 8 ft 3 in. The pontoons are never ballasted and are divided into 10 water-tight compartments. They are penetrated in the lower part of each end by a 42-in. in diameter propulsion tube set at a 45° angle to the pon­ toons' keel. The inner ends of the tubes are located at the extremities of the pontoons. A 38 in. in diameter, rever­ sible propeller is set in each of the tubes.

/ / PONTOONS (

\ : CONTROL CONSOLE \ L \

'''-_PROPULSION TUBE

{PEDESTAL FOR HEAVY PACKAGE

ENGINE PUMP UNIT PROPULSION

UNIT _.-...... >L---'=:::::r'I:======:::::=b=-II.J=l

~-~"'-~~·-~~~-----~-~~~-~~--+I~- \, __ c~ ______~-2..._// Fig. 3-Side view of the loaded rigmover being towed to Fig. lA-Schematic drawing of rigmover (not to scale). next location.

MAR{'H, 1962 229 ing within each support leg. The legs are pin-connected to hp reversible, hydraulic motor (Fig. 5). Each unit has the pontoons, and stability is maintained in the structure a 38-in. in diameter, 28-in. pitch, stainless-steel propeller. by sliding guides within the yoke truss. The four units give the loaded rigmover a top speed of 3.2 knots at 2,000-psi operating pressure. Principal Mechanical Features A pair of double-drum anchor winches are located on raised platforms above the propulsion-system power units Hydraulic motors furnish almost all of the power trans­ (Figs. 4 and 6). The anchors are used at the rare times mitted to the various mechanical components of the rig­ when it is necessary to moor the rigmover in open water mover. The propulsion and lifting systems are hydraulically while awaiting improved weather conditions. powered, as are the anchor winches and water pump. Other minor items are electrically driven. Electric lighting power is furnished by a 60-hp, 40 kw, AC diesel-electric generator unit. A special 125-v DC The prime movers in the hydraulic system are three electrical system is used on the electro-hydraulic con­ 200-hp diesel engines driving three 9-cylinder, positive­ trols. The direct current is taken from a nickel-cadmium displacement, variable-stroke pumps. These pumps deliver battery set which is charged by a hydraulically-driven DC 145 gal/min. at 3,000 psi while turning 900 rpm. Compen­ generator. sating devices on the pumps maintain the desired operating pressure in the system regardless of volumetric demands. The entire rigmover is controlled from a console located Two of the engine-pump units are located on the pontoons, one on each of the points of the "U" (Fig. 4). They power the propUlsion system. The lifting system is powered by the Downloaded from http://onepetro.org/JPT/article-pdf/14/03/228/2213322/spe-148-pa.pdf by guest on 27 September 2021 third unit which is located on the port side of the yoke. The rated working pressure is 2,000 psi and the rated maximum for emergency service is 3,000 psi. The propUlsion units resemble an outboard motor and are located in vertical wells which intersect the propul­ sion tubes in the pontoons. Each unit is powered by a 150-

Fig. 6-0utboard view of port pontoon with yoke in raised position.

Fig. 4-Forward portion of starboard pontoon showing (from left to right) hydraulic motor on propulsion unit, diesel engine-pump unit, anchor winch on rai ed platform, leg housing, hea''Y-package pedestal, and light­ package rolling beam.

Fig. 5-Propulsion unit hydraulic motor. Fig. 7~ControI console.

230 JOURNAL OF PETROLEUM TECHNOLOGY at the center of the transverse section of the yoke (Fig. 7). All the propulsion and lifting controls and instruments are within easy reach and sight of the operator. The steer­ ing device consists of 10 push-buttons. Eight of these are in a circular pattern at 45° intervals, and the remaining two are in the center of the circle. The rigmover can be maneuvered forward, backward, to the side, or diagonally by pressing the button at the same compass point as the desired motion. The rigmover can also be caused to spin about its own axis by pressing one of the center buttons. The steering control buttons actuate solenoid valves which direct power oil to any selected pair of motors or to all four motors. As mentioned previously, the entire yoke structure is raised and lowered to pick up and place the drilling pack­ age. Twelve-inch in diameter by lO-ft stroke hydraulic pistons housed within the legs supply the lifting force. The lift system uses 2,500- to 3,000-psi pressure to pick up

the load. An oil metering system assures that an approxi­ Downloaded from http://onepetro.org/JPT/article-pdf/14/03/228/2213322/spe-148-pa.pdf by guest on 27 September 2021 mately equal amount of hydraulic oil is supplied to each piston. A bleeder control valve and a remote leg-height indicator permit the operator to maintain a continuously level lift. A fail-safe system of leg pawls, or dogs, pre­ vents the yoke and its load from falling in the event of a failure in the hydraulic lifting system (Fig. 8). Fig. 8-Leg housing with fail-safe locking pawl, flow control valves, and rolling beam in extended posiiton. Foundation, Substructures and Drilling Equipment pins on the base beams of the substructures match recep­ Creole currently uses two types of re-inforced-concrete­ tacles on the well foundations. pile well foundations. The first type is an eight-pile foun­ dation which is used on wells to be drilled to less than 8,000 ft in depth. For wells deeper than 8,000 ft, a 12- Advantages and Limitations pile foundation is used. The pile sizes vary greatly in both One advantage found in the use of the rigmover is that length and diameter, depending on the depth of water it permits the company to move all of its drilling equip­ in which the well is to be drilled. All vertical piles, four ment quickly and efficiently from one well to the next on in the first case and eight in the latter, are individually two compact units. All the basic equipment required to weighted with 200-tons dead weight. A square, I-beam tie­ drill a well are carried on the rigmover package and the frame joins the groups of piles with the top of the frame barger-tender. Rigging-up at a new location consists es­ being 14 ft above the water. sentially of connecting mud, water, fuel, electric and hy­ Substructures are classified in the same manner as foun­ draulic lines, and lowering the connecting ramp between dations. A light sub-base in conjunction with a 24 X 129 rig and barge. The savings in rig-up time amount to ap­ ft standard derrick is used on wells drilled to less than proximately 12 to 24 hours with light drilling rigs, 48 8,000 ft and on most workover jobs. Seven of these bases hours with heavy drilling rigs, and eight hours for work­ were designed and built by Creole and are modifications over or repair rigs. of the well platform used on pre-rigmover wells. Four of Another advantage is that it is no longer necessary to them are used in medium-depth drilling and deep repair place a permanent derrick on each well. Also, the rigmover work, and three are used in medium-depth repairs and tie-frame is less expensive than the previously-used well workovers. Six heavy, double-decked structures built in the platform. U. S. are used on wells deeper than 8,000 ft. The derricks It was originally intended that the rig mover should be used on these units are 30 X 136 ft. Only four of the completely self-sufficient and be able to move both itself heavy substructures were equipped with draw-works. and the drilling barge from one location to the next. In The light rigmover packages are equipped with a 600-hp actual practice, however, due to lack of effective power diesel draw-works. The heavy packages use an 800-hp for rapid movement as well as changes in operating pro­ draw-works. Both types are moved with rotary table, crown cedures, the unit maneuvers under its own power only and traveling blocks, standpipe and small accessory equip­ when actually lifting or placing a package. At all other ment in place. The heavy sub-base has storage space on the times it is towed by a tug. The loaded rigmover is unable lower deck for all of its BOP equipment. The fully rigged to make headway against a 20-knot wind, and waves over light and heavy packages weigh 125 and 225 tons, respec­ 2 ft in height make operations almost impossible. This tively. restriction has not been too important, as these weather The substructures all have cantilever pick-up arms, with and wave conditions exist on Lake Maracaibo for only centering receptacles or sockets, extending from each about 2 per cent of the time. corner. The rigmover has two sets of pick-up points: (l) Although the time required to effect a rig move has the heavy package is picked up on four pedestals fitted been materially reduced, the amount of auxiliary equip­ with locator pins which are on the upper deck of the ment required has not. The crane barge formerly required rigmover (Fig. 4) ; and (2) the light packages are sup­ to remove and place the drilling equipment must still ported by four roIling beams which can be extended to be present to pick up the anchors of the barge-tender. The the inboard sides of the yoke (Figs. 4 and 8). Four locator crane barge normally delivers the surface casing for the

MARCH, 1 962 2SI next well at the same time, so a double purpose is served All of Creole's drilling-rig moVes are currently being by its presence. In addition to the crane barge, two tugs handled by the rigmover, and an ever-increasing number are required for each rig move-one for the tender and of repair rig moves. As many as three movers per day have one for the mover. In pre-rigmover days, the rig move was been made but, due to the large areal extent of the com­ accomplished with one tug. pany's holdings in Lake Maracaibo, it is doubtful that an average rate of one move per day could be handled Typical Rigmover Operation with one mover. Even at this rate, a certain amount of lost time would be incurred because of conflicting moving The rigmover is ordinarily berthed in Creole's harbors schedules. If this problem arises, it can be solved either at either La Salina or Lagunillas. When a call to move a by assembling more packages, so that they can be leap­ rig is received from the drilling or operations group, the frogged ahead of the drilling barges, or by buying another rigmover, or "cangrejo" (Spanish for crab) as it is known rigmover. At the present time, all the light-drilling and to the Venezuelans, is towed to the pick-up point (Fig. production packages are in continuous use, but only one 1 ). The two-man rigmover crew travels by speed launch, deep-drilling unit is active. usually leaving shore several hours after the tug. After starting the diesel engines and generator unit, the assistant Conclusions casts off the tow line and the operator maneuvers the craft near the well platform. He checks wind and current di­ Despite its highly experimental, unique and costly rection, and the drilling package for projecting equipment, nature, the Creole marine rigmover has proved to be a etc. The operator then starts his approach from behind time- and money-saving device. Very little lost time and Downloaded from http://onepetro.org/JPT/article-pdf/14/03/228/2213322/spe-148-pa.pdf by guest on 27 September 2021 the draw-works. The forward pedestals or rolling beams no accidents of import have resulted from its use. are maintained 6 in. to 1 ft lower than the rear ones to assure easy clearance. When the operator has positioned Due to the ever-changing nature of the petroleum in­ the pedestals below the rear centering receptacles on the dustry, it is quite possible that the Creole rigmover may substructure, he raises the entire yoke (Fig. 2). As the be outmoded in the near future, the most likely reason centering pins engage the rear receptacles, the forward being the introduction of floating drilling platforms. Until receptacles are also automatically positioned. The load is such time arrives, however, the operation of the rigmover then leveled and lifted clear of the foundation, and the will prove to be increasingly attractive. Its total cost of mover backs away from the platform. The load is brought operation should remain relatively constant, while the to its low position to maintain better stability (Fig. 3). unit moving cost continues to decrease as the usage of The tug takes the rigmover under tow to the next location the mover increases. The entire capital investment in the where the entire previous procedure is reversed. The drill­ rigmover program was paid out in Nov., 1961, a little over ing package is left on the new foundation awaiting the ar­ two years after becoming operational. *** rival of the barge-tender which is towed separately. The rigmover is secured and returned to its base or moved to its next job. R. E. KUNZI formerly was employed Economics and Utilization as a senior petroleum engineer in Creole Petroleum Corp.'s Drilling Engineering The total capital investment in the rigmover is $1.2 Section in Tfa Juana, Venezuela. He left million. In addition, over $500,000 have been spent in Creole in Jan., 1962, to accept a posi­ building and modifying the 13 associated substructures tion with Global Marine Exploration and their derricks. Even though the investment is very Co. in Los Angeles. A 1951 petroleum large, Creole feels that it is money well spent because engineering graduate of the U. of Cali­ of the savings realized from the elimination of derricks, fornia at Berkeley, he worked for the the lower cost of rigmover-type well platforms and the less­ Union Oil Co. of California before join­ tangible savings in rig time. ing Creole in 1957.

232 JOURNAL OF PETROLEUM TECHNOLOGY