NOV（National Oilwell Varco）公司是目前全球最大的石油钻采设备供应商，有谁能详细解答NOV的成长历程？

【专家解说】：　　National Oilwell Varco is the leading provider for the worldwide oil and gas industry and has been dedicated to providing the highest quality oilfield products and services for more than 140 years. National Oilwell Varco is the single source for all of your rig equipment, integrated systems, downhole tools, and supply chain solutions. From a spare part to a comprehensive drilling system ?and from a generic valve to a fully integrated supply chain process, National Oilwell Varco delivers unlimited customer solutions. By constantly developing and acquiring new technologies and services to better serve future customer requirements, National Oilwell Varco will continue to be the premier source for diversified products and services worldwide. 　　National Oilwell Varco designs, manufactures and sells the major mechanical components for both land and offshore drilling rigs as well as complete land drilling and well servicing rigs. The major mechanical components include drawworks, mud pumps, power swivels, SCR systems, traveling equipment and rotary tables. The Company also designs and manufactures a broad offering of downhole products, including drilling motors and specialized drilling tools for rent and sale. National Oilwell Varco also provides distribution services through its network of distribution service centers located in the United States, Canada and near major drilling and production activity worldwide. 　　By continuously increasing the breadth and depth of products and services offered, National Oilwell Varco has become the steward of more than 40 industry-leading brand names during the past 140 years. These strategic mergers and acquisitions have included some of the leading names in the upstream oil and gas industry, and allow National Oilwell Varco to offer a full line of high-quality products and solutions. 　　History of Acquisitions 　　1892 - 　　"Oil Well Engineering" acquires Continental Tube Works in Pittsburgh 　　1902 - 　　National Supply "(National)" acquires California Supply 　　1920 - 　　National acquires Union Tool 　　1928 - 　　National purchases 1/2 interest in Oil Well Engineering 　　1928 - 　　National acquires Superior Engine Company 　　1929 - 　　Oilwell acquires Wilson-Snyder Manufacturing Corp of Pittsburgh 　　1930 - 　　United States Steel acquires Oil Well. Oil Well becomes the Oilwell Division 　　1940 - 　　National acquires Central Tube Company 　　1944 - 　　Oilwell Division acquires Witte Engine Works 　　1945 - 　　Oilwell Division acquires Neilsen Pump Company 　　1975 - 　　National Supply buys remaining shares of Oil Well Engineering 　　1978 - 　　National acquires PAR Industries 　　1978 - 　　National acquires Derrick Service Int'l 　　1978 - 　　National acquires Compressor Pump and Engine 　　1979 - 　　National acquires Baylor 　　1979 - 　　National acquires small oilfield services company in Oklahoma City and calls it National Chemicals 　　1980 - 　　National purchases assets in Grenco Corporation 　　1981 - 　　National Supply (Armco) acquires Equipetrol, S.A. 　　1987 - 　　National Supply merges with USS Oilwell 　　1989 - 　　National Oilwell acquires Mission 　　1997 - 　　National Oilwell acquired Ross Hill Controls 　　1997 - 　　National Oilwell acquired PEP, Inc. 　　1997 - 　　National Oilwell acquired Dreco Energy Services Ltd. (Canada) 　　1998 - 　　National Oilwell acquired Versatech International Ltd. (Canada) 　　1998 - 　　National Oilwell acquired Specialty Tools Ltd. (Scotland) 　　1998 - 　　National Oilwell acquired Phoenix Energy Products (Harrisburg, Wooley, M&W, CDI) 　　1998 - 　　National Oilwell acquired Roberds -Johnson Industries, Inc. 　　1998 - 　　National Oilwell acquired DOSCO (Canada) 　　1999 - 　　National Oilwell acquired Dupre’ Supply Company & Dupre’ International, Inc. 　　1999 - 　　National Oilwell acquired CE (Continental Emsco) Drilling Products & Wilson Mobile Rig 　　1999 - 　　National Oilwell acquired Skytop Brewster Company 　　2000 - 　　National Oilwell acquired Republic Supply Company 　　2000 - 　　National Oilwell acquired Hitec ASA (Norway) 　　2000 - 　　National Oilwell acquired IRI International Corporation 　　2000 - 　　National Oilwell acquired Wheatley Gaso Omega 　　2000 - 　　National Oilwell acquired Baylor Company 　　2000 - 　　National Oilwell acquired Hart Sales Company 　　2001 - 　　National Oilwell acquired Maritime Hydraulics (Canada) Ltd. 　　2001 - 　　National Oilwell acquired DEMIJ (Rotterdam) 　　2001 - 　　National Oilwell acquired Tech Power Controls Co. 　　2001 - 　　National Oilwell acquired Rye Supply Company, Inc. 　　2001 - 　　National Oilwell acquired Texas Oil Works Supply, Inc. 　　2001 - 　　National Oilwell acquired HSI-Houston Scientific International, Inc. 　　2001 - 　　National Oilwell acquired AMTEX Pump & Supply 　　2001 - 　　National Oilwell acquired Rigquip Division Assets (Noble Drilling U.K. Limited) 　　2002 - 　　National Oilwell acquired HAL Oilfield Pump & Equipment (HALCO) 　　2002 - 　　National Oilwell acquired Integrated Power Systems 　　2002 - 　　National Oilwell acquired STS Oilfield Specialty & Supply, L.L.C. 　　2002 - 　　National Oilwell acquired Hydralift ASA 　　2003 - 　　National Oilwell acquired LSI Specialty Electrical Products 　　2003 - 　　National Oilwell acquired MonoFlo, Inc. (US) & Mono Group (UK) 　　2003 - 　　National Oilwell acquired Øgrey Mekaniske Verksted AS (Norway) 　　2005 - 　　National Oilwell merges with Varco becoming National Oilwell Varco 　　Milestones 　　1862 - 　　John Eaton Company established to furnish oilfield equipment in Oil City, PA, and surrounding area. 　　1867 - 　　Original line of products made in own shop, including bits, cable tools, temper screws, bailers, bull wheels, derricks, etc. 　　1869 - 　　John Eaton and EH Cole joined to form Eaton and Cole to furnish oilfield equipment. 　　1884 - 　　Additional own-make products, including: complete line of cable-tool drilling, fishing, and clean-out tools. 　　1884 - 　　Additional own-make products, including: standard and portable rigs, including derricks, rig irons, steam engines. 　　1884 - 　　Additional own-make products, including: casing and tubing elevators and tongs. 　　1886 - 　　Under-reamers. 　　1892 - 　　Complete all-steel drilling rig, including 72 ft. derrick, crown and traveling blocks, piston-valve twin- cylinder steam engines. 　　1901 - 　　Drawworks, swivels, bits. 　　1904 - 　　Portable all-steel drilling machines for cable-tool drilling . 　　1907 - 　　Rotary tables, portable all-steel drilling machines for rotary drilling. 　　1911 - 　　Steam driven slush pumps. 　　1912 - 　　"Mud Hog" and "Giant Mud Hog" series steam slush pumps. 　　1913 - 　　Union Tool Co. (later purchased by National Supply Co.) introduced its first rotary table. 　　1913 - 　　Union Tool Co. (later purchased by National Supply Co.) made offset steel roller chain with replaceable steel pins and bushings. 　　1916 - 　　Power slush pumps. 　　1918 - 　　Designed and patented "Imperial" Rotary Swivel. 　　1923 - 　　Make-and-break rotary tables. 　　1923 - 　　Hild differential electric drives for rotary drilling. 　　1926 - 　　Long stroke (18") Wilson-Snyder Steam Slush Pump. 　　1927 - 　　Fully-enclosed roller-bearing twin-cylinder steam engines. 　　1928 - 　　Spang, Chalfant pioneered "Magna Glo" inspection to uncover cracks in pipe. 　　1930 - 　　Emsco developed a line of duplex double acting slush (mud) pumps. 　　1930 - 　　National designed an improved band brake system for drawworks ("K" Brake) with increased leverage at optimum handle position. 　　1930 - 　　High pressure (350 psi working pressure) boilers. 　　1930 - 　　20" stroke steam slush pumps. 　　1930 - 　　Fully-enclosed oilbath rotaries. 　　1933 - 　　National started using "V" packing rings, coil spring, in wash pipe packing assemblies on rotary drilling swivels. 　　1933 - 　　Vertical twin-cylinder steam engines. 　　1934 - 　　Hydraulic feed controls for rotary drilling. 　　1934 - 　　Di-Hard slush pump liners. 　　1935 - 　　National introduced its "C" line of power duplex slush pumps, 1500 to 3000 PSI, with patented baffle chamber. 　　1935 - 　　National designed, developed, and made a new patented main bearing for rotary drilling swivels. 　　1935 - 　　Rotary drilling units (packaged unit providing independent drive to the rotary from a steam engine) . 　　1936 - 　　20" stroke power slush pumps. 　　1939 - 　　Rotary drilling unit with drive from internal combustion engine through hydraulic torque converter. 　　1940 - 　　National designed an improved 2-plate clutch for drawworks which was first installed on a 33-62-FE drawworks 1500 Hp steam driven. 　　1940 - 　　Triplex steam slush pumps. 　　1941 - 　　National furnished chain compounded sectional drive groups (as alternate to V-belt) to power drawworks, rotary, and mud pumps. 　　1945 - 　　Completely air controlled power rigs (drawworks and drives). 　　1946 - 　　National introduced "Gammaloy" drill collars, as a less expensive nonmagnetic stainless steel to replace K-Monel material. 　　1946 - 　　Portable derricks. 　　1947 - 　　National Hydraulic Coupling introduced as a fluid cushion connection between engines and drive group to absorb shock loads. 　　1947 - 　　National designed, developed, and made a new "Quick-Seal" hose connections for rotary swivel or standpipe goosenecks. 　　1949 - 　　National type "A" single stage Torque Converter, designed specifically for drilling rigs, introduced for drive group compounds. 　　1949 - 　　Drilling depth record of 20,521 ft set at Rock Springs, Wyoming by a rig using National drilling equipment. 　　1949 - 　　Automatically regulated hydraulic feed controls for rotary drilling. 　　1950 - 　　National designed an improved drum type clutch for drawworks (Dy-A-Flex) with increased reliability and simpler to service. 　　1951 - 　　Introduced overrunning clutch between drawworks drumshaft and auxiliary brake for mechanical rigs. 　　1951 - 　　National designed, developed, and made a new patented "Uniflex" wash pipe & packing box for rotary drilling swivels. 　　1952 - 　　Introduced "Micromatic" drilling controls for drawworks to automatically feed off pipe as the hole is drilled. 　　1953 - 　　Drilling depth record of 21,482 ft set in Paloma Field, California by a rig using National drilling equipment. 　　1953 - 　　Extreme high horsepower, high pressure power slush pump for jet bit drilling. 　　1955 - 　　Hook blocks. 　　1956 - 　　National obtained patent on improved wash pipe for "Uniflex" wash pipe & packing box for rotary drilling swivels. 　　1956 - 　　National introduced 2 step "Spirallel" integral drawworks drum grooving as an improvement for spooling wire rope onto the drum. 　　1956 - 　　Drilling depth record of 22,570 ft set by a drilling barge south of New Orleans using National drilling equipment. 　　1958 - 　　Triplex plunger mud pump unit w/ 2-speed transmission and direct connected engine for high pressure & slim hole drilling. 　　1959 - 　　Lever lift drilling masts. 　　1959 - 　　Induction-hardened steel slush pump liners. 　　1959 - 　　Swivels with quick removable wash pipes. 　　1960 - 　　Introduced "Seal-Lock tubing, a premium threaded and coupled connection for deep wells. 　　1962 - 　　Introduced a subsea christmas tree on a producing well in the Gulf of Mexico. 　　1963 - 　　Continental Emsco introduced the Electrohoist II Drawworks. 　　1964 - 　　Furnished remotely installed well head in 600 ft water depth. 　　1967 - 　　Introduced A37-1/2 Rotary. 　　1968 - 　　Introduced a mechanical jacking system for offshore jack-up rigs featuring high efficiency lifting mechanism with opposed pinions. 　　1968 - 　　National's first triplex mud pumps, model 10-P-130, rated for 1300 HP, are first used on a land rig. 　　1969 - 　　Continental Emsco introduced the F1000 Triplex Mud Pump. 　　1969 - 　　Furnished an early subsea production system in the Norwegian sector of the North Sea. 　　1969 - 　　Oilwell's first triplex mud pumps, model 1400-PT, rated for 1400 HP, are shipped. 　　1970 - 　　Introduced new line of Oilwell "PC" (Positive Centering) Swivels ranging from 100 to 650 tons capacity. 　　1972 - 　　Oilwell A1400-PT and A1700-PT single acting Triplex Slush (Mud) Pumps fitted with fluid ends for high volume application. 　　1973 - 　　Oilwell A49-1/2 Rotary for offshore drilling. 　　1974 - 　　Introduced Oilwell 350-PT single acting triplex mud pumps designed for transport by air-lift. 　　1977 - 　　Kremco completes its first in-house designed workover rig, model K600. 　　1977 - 　　Dreco designs and constructs two covered bolted beam leg derricks. 　　1978 - 　　Dreco's first originally designed drawworks, 400 HP, is designed and built by Glenn Knutson. 　　1979 - 　　Dreco builds its first 2.5 million lb mast and substructure. 　　1979 - 　　Dreco introduces a new patented beam leg mast with special hinged back bracing for improved transporting on land rig moves. 　　1980 - 　　"Slingshot" substructure allowing installation of major components & raising of mast at ground level, before elevating substructure. 　　1981 - 　　Dreco develops proprietary designs for various drilling equipment, including rotary tables, traveling blocks, and triplex mud pumps. 　　1981 - 　　Dreco introduces its "Superior" Drawworks models 700UE, 700M, and 1000UE at the OTC in Houston. 　　1981 - 　　Dreco introduced the first 4,000 HP Drawworks on a land rig. 　　1981 - 　　Dreco introduced the first Traveling Block rated for 1,250 tons. 　　1982 - 　　Dreco introduced the first 156 ft "Slingshot" Mast and substructure rated for 2,500,000 lb, with 40 ft high drill floor, for a land rig. 　　1983 - 　　Dreco designs the "Sandmaster", a self-propelled workover/drilling rig for desert operations. 　　1983 - 　　Griffith introduces a hydraulic/mechanical drilling jar to the Canadian oilpatch. 　　1984 - 　　Griffith designs and builds the "Torquemaster", a tool break-out machine which becomes a major product line for Griffith. 　　1985 - 　　GH introduced a new patented disc brake system designed for drawworks (design purchased by National in Jan 1987). 　　1986 - 　　Griffith designs and tests its first proprietary downhole steerable drilling motor, tradenamed "Trudril". 　　1986 - 　　Dreco develops a cantilevered arctic rig design featuring a sliding drill floor to permit the drilling of more wells from a smaller pad. 　　1986 - 　　Dreco introduced a new BOP handling system powered by hydraulic cylinder operated wireline hoists. 　　1987 - 　　Dreco introduces the "Kremcovets" prototype service rig at tradeshow in Moscow, which is a Kremco rig on a Soviet Kirovets tractor. 　　1988 - 　　Dreco introduced a new patented capping beam "Gripper" system for horizontal jacking of rig substructures on offshore platforms. 　　1990 - 　　Continental Emsco shipped model FC-2200 Triplex Mud Pumps. 　　1990 - 　　National-Oilwell shipped model 14-P-200 Triplex Mud Pumps (later uprated to 2200 HP). 　　1990 - 　　National-Oilwell installed a PS-500 Top Drive, with patented rotating side skid, allowing it to swing out of tripping path in minutes. 　　1992 - 　　Dreco introduced a new "Lift and Roll" skidding system for horizontal moving of rig substructures on offshore platforms. 　　1992 - 　　Drawworks electric remote controls combined with PLC kinetic energy monitor system to prevent traveling block overspeed. 　　1993 - 　　Dreco designs and constructs its first coiled tubing rigs. 　　1995 - 　　Dreco introduces its new injector head for coil tubing rigs at the OTC in Houston. 　　1995 - 　　Dreco, in partnership with Hitec, designed and made first variable frequency AC driven drawworks (no main drum or aux. braking). 　　1997 - 　　Continental Emsco shipped 5,000 HP Electrohoist Drawworks for offshore rig. 　　1997 - 　　Dreco introduced a new "slip" type rotary deadline anchor that allows drill line to be "cut & slipped" without removal from anchor. 　　1997 - 　　National-Oilwell introduced a high pressure hydrodynamic wash pipe packing assy., using a Kalsi seal, w/ 4" bore for Drilling Swivels. 　　1998 - 　　Continental Emsco introduced the first 60-1/2" rotary, model T-6050, for offshore rigs to handle large diameter riser pipe. 　　1999 - 　　National-Oilwell shipped two Dreco designed semi-automated trailerized doubles land drilling rigs, with Hitec Cyberbase controls. 　　1999 - 　　National Oilwell, in partnership with Hitec, designed and made first AC driven "Active Heave Compensating Drawworks" for floating Drilling Rigs. 　　1999 - 　　SAP was implemented in distribution groups to facilitate inventory control, financial planning, logistics, purchasing, and e-commerce worldwide. 　　2000 - 　　Pete Miller named COO for National Oilwell. 　　2000 - 　　National Oilwell implemented Customer Connect, an online application to provide customers with detailed analysis of their spend. 　　2001 - 　　National Oilwell receives order for two Santa Fe jack-up rigs. 　　2001 - 　　Pete Miller named CEO. 　　2001 - 　　BroadVision-based online web catalog implemented to allow ordering via the internet. 　　2002 - 　　National Oilwell produced the PowerStroke Dual Hydraulic Drilling Jar. 　　2002 - 　　National Oilwell introduced the Multi-Opening Circulating Sub, eliminated the requirement to pull out of hole and remove drop-ball. 　　2002 - 　　National Oilwell introduced the Mini-Tong to improve safety during makeup and breakout connections on small tools and pipes.