“DRILLING” MIDDLE EAST TECHNICAL UNIVERSITY Department of Petroleum and Natural Gas Engineering “DRILLING” Dr. Mahmut Parlaktuna Res. Assist. Sevtaç Bülbül Spring 2008

PETROLEUM Petroleum Petra ROCK oleum OIL

PETROLEUM a mixture of naturally occurring hydrocarbons may exist in the solid, liquid or gaseous states, depending upon the conditions of pressure and temperature When the chemical mixture is composed of molecules of small size; gas at normal T &P NATURAL GAS When larger molecules; liquid at normal T&P CRUDE OIL (Approximately 11-13wt % hydrogen and 84-87 wt % of carbon. Traces of oxygen, sulphur, nitrogen and helium maybe found as impurities in crude oil.) In Pennsylvania,

PETROLEUM Oil is formed in a source rock, along with water and gas. Over millions of years, the oil and gas float upwards along a migration path. If oil and gas does not rise to the surface, it collects in a reservoir; a rock that has spaces where oil can collect. (e.g. Sandstone) There must also be a trap - a rock structure that forms an impermeable seal above and around the reservoir rock (e.g. clay and shale)

DRILLING After an oil company’s exploration geologists and geophysicists have obtained and analyzed the data from a prospective petroleum site, the landman has secured a lease, drilling permits and other preliminary papers are in order DRILLING

CABLE-TOOL DRILLING Repeatedly dropping a heavy metal bit into the ground, eventually breaking through rock and punching a hole through to the desired depth. The cuttings removed with a “bailer”, an open tube with a valve at the bottom. With today’s technology, cable-tool drilling is almost not in use. First oil well built in 1859 by Edwin L. Drake in Pennsylvania

ROTARY DRILLING Rotary drilling uses a sharp, rotating drill bit to drill the ground. As the hole gets deeper, pipes are added to the drill bit to allow it to go further. Most land rotary rigs are portable and moved to different drilling sites. Some offshore rotary rigs are mobile; a boat tows the rig onto the drill site. Some offshore rigs are immobile; they stay in the site throughout the life of the field.

RIG COMPONENTS Power System Hoisting System Rotating System Circulating System

POWER SYSTEM Provides the power to the entire rig. Diesel engines compose the majority of power sources on rotary rigs. Diesel engines drive large electric generators. The generators, in turn, produce electricity that is sent through cables to electric switch and control gear.

HOISTING SYSTEM The hoisting system is used to raise and lower pipe in and out of the hole and to support the drill string to control the weight on the drill bit during drilling. The hoisting system consists of derrick, traveling and crown blocks, the drilling line the drawworks

HOISTING SYSTEM The derrick is a steel tower that is used to support the traveling and crown blocks and the drill string. The drawworks is a big, heavy piece of machinery. It consists of a revolving drum around which the wire rope called drilling line is spooled or wrapped. The crown and traveling blocks are a set of pulleys that raise and lower the drill string.

ROTATING SYSTEM The rotary system includes all the equipment used to achieve bit rotation. The main parts of the rotary system are: Swivel Kelly Rotary drive Rotary table Drill pipe Drill collars

ROTATING SYSTEM The swivel supports the weight of the drill string and permits rotation. The swivel is attached to the bottom of the traveling block and permits the drill string to rotate.

ROTATING SYSTEM The kelly is the first section of pipe below the swivel. The outside cross section of the kelly is square or hexagonal to permit it to be gripped easily for turning. Torque is transmitted to the kelly through kelly bushings, which fit inside the master bushing of the rotary table. A kelly saver sub is used between the kelly and the first joint of drill pipe.

ROTATING SYSTEM As the rotary table turns the kelly is also turned. The movement of the kelly rotates the drill string and the drill bit. The major portion of the drill string is composed of drill pipe. Drill pipe is round steel tubes about 30 feet long with a diameter of from 4 to 5 inches. The lower section of the rotary drill string is composed of drill collars. The drill collars are thick-walled heavy steel tubulars used to apply weight to the bit and prevent buckling of the drillpipes.

ROTATING SYSTEM The process of drilling a hole in the ground requires the use of drilling bits. Rotary drilling bits usually are classified according to their design as: Drag bits: Fixed cutter blades, rotate as a unit with the drill string. Rolling cutter bits: Usually three cones that are free to turn as bit rotates.

CIRCULATING SYSTEM Circulating system circulates drilling fluid. The drilling fluid is most commonly a suspension of clay and other materials in water and is called drilling mud. Drilling mud removes cuttings from the hole and cools and lubricates the drilling bit. The principal components of the circulating system include: Mud pumps and mud pits Mud-mixing equipment Contaminant-removal equipment

CIRCULATING SYSTEM The drilling mud travels: Steel tanks Mud pump Drill string Bit Annular space btw drill string & hole to the surface Contaminant-removal equip. Back to the suction tank.

CIRCULATING SYSTEM The mud pump takes in mud from the mud pits and sends it out a discharge line to a standpipe. The standpipe is a steel pipe mounted vertically on one leg of the mast or derrick. The mud is pumped up the standpipe and into a flexible, very strong, reinforced rubber hose called the rotary hose or kelly hose. The rotary hose is connected to the swivel. The mud enters the swivel, goes down the kelly, drill pipe and drill collars and the bit. It then does a sharp U-turn and heads back up the hole in the annulus.

CIRCULATING SYSTEM Finally the mud leaves the hole through a steel pipe called the mud return line and falls over a vibrating, screen like device called the shale shaker. Agitators installed on the mud pits help maintain a uniform mixture of liquids and solids in the mud. If any fine silt or sand is being drilled, then devices called desilters or desanders may be added. If there are small amounts of gas in the formation, a device called degasser is also added.

DRILLING IS A COMPLEX OPERATION THAT INCLUDES MANY DIFFERENT PROCESSES, TECHNOLOGIES AND DISCIPLINES.

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