1、 English for Offshore Oil&Gas Engineering127CONTENTSCONTENTSIINTRODUCTION1First Offshore Operations in the World1The Scope of Offshore Operations21. DRILLING RIGS4Bottom-Supported Units5Floating Units13Summary222. DRILLING A WELL23Bits and Drilling Fluid23Circulating System24Rotating Systems27Power
2、System32Hoisting System34Drilling Personnel39Summary463. EXPLORATION DRILLING47Selecting a Rig47Drilling from Bottom-Supported Units49Drilling from Floating Units55Formation Evaluation66Well Abandonment68Summary694. DEVELOPMENT DRILLING AND COMPLETION70Drilling Platforms70Mobile Offshore Drilling Un
3、its76Directional and Horizontal Drilling78Well Completion79Summary825. OIL AND GAS84Characteristics of Oil and Gas84Characteristics of Rocks85Types of Rocks85Origin of Oil and Gas86Migration and Accumulation of Oil and Gas87Traps88Summary916. EXPLORATION92Magnetic Surveys93Gravity Surveys93Seismic S
4、urveys95Survey Locations98Obtaining Drilling Rights98Summary997. PRODUCTION AND WORKOVER101Reservoir Drive Mechanisms101Handling Oil, Gas, and Water103Artificial Lift109Additional Recovery Techniques111Well Servicing and Workover113Summary1158. OIL AND GAS TRANSPORTATION117Transportation by Pipeline
5、117Transportation by Tanker123Summary1249. REVIEW126INTRODUCTIONPeople use oil and gas more than any other source of energy. From oil, refineries make or extract gasoline, diesel fuel, and lubricants. Petrochemical plants make plastics and fertilizers. Natural gas heats our homes and fires steam gen
6、erators to make electricity. Without oil and gas, everyones life would be very different. The petroleum industry produces oil and gas from special layers of rocks called reservoirs. Like a multilayered cake, additional beds of rock lie above and below these reservoirs. And, like the frosting on a ca
7、ke, a relatively thin layer of ground sometimes covers the rock layers. On the other hand, the frosting may not be dry land; it may be water instead. Since oceans and seas cover about three-fourths of the earth, it is no surprise that water also covers rock layers.Operating in oceans or seasoffshore
8、presents special problems to oil producers that they do not have to face on land sites. This book examines many of the special conditions the marine environment imposes on finding, producing, and transporting oil and gas.First Offshore Operations in the WorldOffshore oil and gas operations began in
9、the late 19th century. Edwin Drake drilled the first oilwell in the U.S. in 1859. He did it on a piece of land near Titusville, Pennsylvania. It was only thirty-eight years later, in 1897, that another enthusiast drilled the first offshore well in the U.S. He drilled it off the coast of Southern Cal
10、ifornia, immediately south of Santa Barbara. In the late 1800s, a group of people founded the town of Summerland, California. The founders picked the site because of its pleasant, sunny climate. Coincidentally, it also had numerous springs. These springs did not, however, produce water: crude oil an
11、d natural gas bubbled out of them. Since Summerland could use gas to light its homes and businesses, and since oil could provide income, the citys residents took an interest in efficiently producing the springs. One citizen, H. L. Williams, was knowledgeable about extracting oil from the earth. So,
12、just as Drake had done earlier in Pennsylvania, Williams drilled wells in the vicinity of the springs. The wells allowed him to extract more oil than if he had simply dammed up the springs. These early wells were successful and, as a result, he and others drilled many more in the area. After drillin
13、g a large number of wells, these early oilmen noticed that those nearest the ocean were the best producers. Eventually, they drilled several wells on the beach itself. But, at this point, the Pacific Ocean stymied them. Experience convinced them, however, that more oil lay in the rock formations bel
14、ow the ocean. The question was how to drill for it.Williams came up with the idea of building a wharf or a pier and erecting the drilling rig on it. The idea worked. His first offshore well, drilled from a wharf made of wooden pilings and timbers, extended about 300 feet (90 meters) into the ocean.
15、On the end of the wharf, Williams erected a drilling rig and used it to drill the first offshore well in the United States. As expected, it was a good producer and before long the entrepreneurs built several more wharves (fig. 1). The longest stretched over 1,200 feet (nearly 400 meters) into the Pa
16、cific.Figure 1. The first offshore wells in the United StatesThe Scope of Offshore Operations Today, offshore activities take place in the waters of more than half the nations on earth. And no longer do primitive, shore-bound wooden wharves confine offshore operators. Instead, they drill wells from
17、modern steel or concrete structures. These structures are, in many cases, movable. What is more, they can float while being moved, and often while drilling. Further, offshore rigs have drilled in waters over 7,500 feet (over 2,200 meters) deep and as far as 200 miles (over 300 kilometers) from shore
18、 Offshore drilling and production have progressed far beyond those early efforts at Summerland. Offshore work today involves a wide range of technologies. These technologies are similar in many cases to those used to find, produce, and transport oil and gas on land. Offshore activities include, how
19、ever, additional technologies that relate to a marine environment. Unlike oil operations on land, offshore operations involve meteorology, naval architecture, mooring and anchoring techniques, and buoyancy, stability, and trim.Drilling and producing oil and gas wells are important phases of offshore
20、 operations, but the scope goes further. Offshore operations also include exploringlooking for likely places where oil and gas may exist in the rock formations that lie beneath the surface of the oceans, seas, gulfs, and bays. In addition, offshore operations include transporting oil and gasmoving t
21、hem from their points of production offshore to refineries and plants on land.1. DRILLING RIGSOnce a company has obtained the right to drill a wildcat, or exploratory, well to see if hydrocarbons exist, they must then select some type of drilling rig. More often than not, they will use a mobile offs
22、hore drilling unit (MODU; pronounced “moe-doo”) (fig. 14).Figure 14. A mobile offshore drilling unit (MODU)Rig owners can move mobile offshore drilling units from one drill site on the water to another. A rig has to be mobile because, after it finishes drilling one exploratory well, a crew has to mo
23、ve it to another site-perhaps nearby, perhaps far away-to drill another.Oil operators use two basic types of MODUs to drill most offshore wildcat wells: bottom-supported units and floating units. Bottom-supported units include submersibles and jackups. Floating units include drill ships and semisubm
24、ersibles (fig. 15). Of the many types of MODUs, operators and contractors use jackups, semisubmersibles, and drill ships the most. Jackups are the most common.Figure 15. Four types of mobile offshore drilling units: (A) jackup; (B) drill ship; (C) submersible; (D) semisubmersibleBottom-Supported Uni
25、tsTwo types of bottom-supported mobile offshore drilling rigs are the submersible and the jackup. Submersible rigs include posted barge submersibles, bottle-type submersibles, and arctic submersible. Jackups differ mainly in the design of their legs and the way in which the manufacturer amounts the
26、rig on the barge hull of the unit.Currently, operators and contractors use jackups to drill most offshore wells. Semisubmersibles run a distant second, while drill ships and other floating units come in third. Submersibles run far behind.When a bottom-supported unit is on site and drilling a well, a
27、 part of its structure is in contact with the seafloor. Special legs or columns support the remainder of the rig above the water (fig. 16). A crew can, however, move the rig, because it can float (fig. 17) Figure 16. This jackup working inIndonesian waters is one of bottom-supported unit. Each of it
28、s legs is incontact with the seafloor.POSTED BARGE SUBMERSIBLESThe first mobile offshore drilling unit built was a submersible. Constructed in 1948, it drilled its first well in the Gulf Mexico in 1949. It was near the mouth of the Mississippi River. It sat in 18 feet (5.5 meters) of water.Figure 17
29、 Four boats tow a jackup as it floats on the waters surface.The rig was a rectangular steel box-a flat-bottomed and flat-sided barge hull. Numerous steel posts rose from the top of the barge hull. The fabricators built a deck on top of the posts. They then placed the drilling equipment on the deck.
30、 Two pontoons, hinged and attached with cable, rode on both sides of the barge hull. These pontoons stabilized the unit (fig 18).When a towboat moved the unit, a crew emptied the water from the barge and the pontoons, which allowed the unit to float (fig. 18, position 1). A boat towed it to the dril
31、ling site and crew members flooded the barge hull; that is, they allowed water toenter the hull at a controlled rate (position 2). As water entered, the hull slowly settled to bottom, eventually coming to rest on the seafloor. Once the main hull rested on bottom, crew members flooded the pontoons (p
32、osition 3), and they too settled to bottom (position 4).Figure 18. The first MODU was a submersible designed to drill in shallow waters.The posts, since they extended some distance above the barge hull, allowed the drilling deck to stay above the waterline. Surface wave motion did not have much effe
33、ct on the unit because the posts were relatively thin and as such were fairly unaffected by wave action. The design worked well, and the entire structure provided a very stable platform from which the rig could drill.These submersibles, often called posted barge rigs, worked so well in shallow water
34、 that manufacturers not use pontoons. In general, companies used them to drill wells in waters no deeper than about 30-35 feet (9-11meters).BOTTLE-TYPE SUBMERSIBLESAs drilling activity increased in the Gulf of Mexico, exploration surveys indicated several potential hydrocarbon reservoirs in the area
35、 Since they lay offshore in waters too deep for posted barge submersibles to handle, in about 1954, rig designers came up with a new submersible, a bottle-type submersible, that could work in deeper water. Instead of a barge hull and pontoons, rig builders constructed the new design from several st
36、eel cylinders. They laid vertically, and then welded them together to form a sort of open cube (fig. 19).Figure 19. When flooded, the bottles cause a bottle-type submersible to submerge to the seafloor.The builders then placed a cylinder much larger in diameter than the rest at each corner of the cu
37、be. They called these four large-diameter cylinders bottles. When flooded, the bottles caused the rig to submerge. When crew members removed the water, the rig floated.The earliest submersibles of this type could drill in waters up to 70 feet (21 meters) deep. Later designs drilled in water depths u
38、p to 100 feet (about 30 meters). One bottle-type submersibles built in 1962 (a triangular shape) could work in water as deep as 175 feet (53 meters).ARCTIC SUBMERSIBLESThe latest submersible rigs are arctic submersibles. In the arctic, open, ice-free water exists only for short periods in the summer
39、 So, the rig owner has to wait for the thaw, then quickly move the rig into position and submerge it before the sea freezes up. While drilling, arctic submersibles can withstand the tremendous Figure 20. A concrete island drilling system forces of moving pack ice that surrounds (CIDS) features a re
40、inforced concrete caissonthem most of the year. with a steel base.One arctic design is a conical drilling unit, or CDU. Another is a mobile arctic caisson, or MAC. Still another is a concrete island drilling system, or CIDS (fig. 20). Heavy steel or concrete wallsa caissonsurround the equipment belo
41、w the waterline. The caisson protects the equipment from damage by moving ice. The drilling deck, or platform, has no square corners so that moving ice can better flow around it.JACKUPSThe industry built the first jackup, or self-elevating, rig in 1954. It rapidly became the most popular design in m
42、obile offshore drilling units. Jackups are popular because they provide a very stable drilling platform, since part of their structures is in firm contact with the bottom of the ocean. They can also drill in relatively deep water (the biggest can drill in waters about 350 feet or 107 meters deep). W
43、hat is more, towboats can easily move a jackup from one location to another.Figure 21. Jackups may have either open-truss legs (A) or columnar legs (B).An offshore drilling contractor can choose from two basic types of jackups. One has open-truss legs. In this design, manufacturers construct the leg
44、s from tubular steel members. They then crisscross the members to make very strong, but relatively light-weight, legs. Open-truss legs look somewhat like the towers that carry high-voltage electric lines across the countryside (fig. 21A).The other jackup has columnar legs. Columnar legs are big stee
45、l tubes (fig. 21B). Columnar legs are less expensive to build than open-truss legs. They cannot, however, withstand bending stresses as well as open-truss legs. As a result, even the largest columnar-leg jackups cannot drill in waters much over 250 feet (75 meters) deep.Whether columnar or truss typ
46、e, the legs of a jackup pass through openings in a barge hull. Three or four legs are common, but some designs call for more or fewer. The deck of the barge serves as the platform for drilling equipment and other machinery.Moving a jackupWhen a crew moves a jackup, it raise, or jacks, the legs up ou
47、t of the water so that the barge floats. With the legs completely out of the water, the rig movers can transport the entire rig to the drilling location (see fig. 17).Usually rig movers tow the rig, but at least one jackup is self-propelled. It has two engine-driven propellers, or screw s, mounted o
48、n the unit that can move it.Sometimes, large ships with flat decks move jackups. Crew members submerge the ship so that its deck is below the water. They then maneuver the rig onto the submerged ships deck. With the rig in place, crew members pump out the water from the ship, which allows it to float. Especially for long-distance moves, ships can carry the jackup at speeds faster than boats can tow it. Ships can also carry semisubmersibles (fig. 22). As you can imagine, a
