drilling tools and types Contents
Introduction
Drilling engineering is one of the most important sections of petroleum engineering because the passageway of the hydrocarbon fluids is the well and the well is gotten by drilling, also well logging and reservoir modeling we get it by drilling, some engineers say ( to get petroleum we have to drill ). The drilling of well accomplished by the rig usually. When a drilling project is commenced, two goals are governing all aspects of it. The first is to realize the well in a safe manner (personal injuries, technical problems) and according to its purpose, the second one is to complete it with minimum cost. Thereto the overall costs of the well during its lifetime in conjunction with the field development aspects shall be minimized. This optimization may influence where the well is drilled (onshore - extended reach or offshore above reservoir), the drilling technology applied (conventional or slim-hole drilling) as well as which evaluation procedures are run to gather subsurface information to optimize future wells.
Drilling technology • Percussion drilling
Rope
Drillstring
” Rotating bit Full cross-section drilling Surface driven • Rotary drilling
Rotary nozzle drilling Subsurface driven Turbine drilling positive displacement motor drilling Electro motor drilling Annular drilling Diamond coring Shot drilling
• Special techniques Abrasive jet drilling Cavitating jet drilling Electric arc and plasma drilling Electric beam drilling Electric disintegration drilling Explosive drilling Flame jet drilling Implosion drilling Laser drilling REAM drilling Replaceable cutterhead drilling Rocket Exhaust drilling Spark drilling Subterrene drilling Terra drilling Thermal-mechanical drilling Thermocorer drilling Drilling tools
Drilling rig A drilling rig is a machine which creates holes (usually called borehole) and/or shafts in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells , or natural gas extraction wells, or they can be small enough to be moved manually by one person They sample sub-surface mineral deposits, test rock, soil and groundwater physical properties, and also can be used to install sub-surface fabrications, such as underground utilities, instrumentation, tunnels or wells. Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or marine-based structures (such as oil platforms, commonly called 'offshore oil rigs' even if they don't contain a drilling rig). The term "rig" therefore generally refers to the complex of equipment that is used to penetrate the surface of the Earth's crust. Drilling rigs can be: • Small and portable, such as those used in mineral exploration drilling, water wells and environmental investigations. • Huge, capable of drilling through thousands of meters of the earth's crust. Large "mud pumps" circulate drilling mud (slurry) through the drill bit and up the casing annulus, for cooling and removing the "cuttings" while a well is drilled. Hoists in the rig can lift hundreds of tons of pipe. Other equipment can force acid or sand into reservoirs to facilitate extraction of the oil or natural gas; and in remote locations there can be permanent living accommodation and catering for crews (which may be more than a hundred). Marine rigs may operate many hundreds of miles or kilometers distant from the supply base with infrequent crew rotation. • Drilling rig classification • There are many types and designs of drilling rigs, with many drilling rigs capable of switching or combining different drilling technologies as needed. Drilling rigs can be described using any of the following attributes:
By power used • Mechanical — the rig uses torque converters, clutches, and transmissions powered by its own engines, often diesel • Electric — the major items of machinery are driven by electric motors, usually with power generated on-site using internal combustion engines • Hydraulic — the rig primarily uses hydraulic power • Pneumatic — the rig is primarily powered by pressurized air • Steam — the rig uses steam-powered engines and pumps (obsolete after middle of 20th Century) By pipe used • Cable — a cable is used to raise and drop the drill bit • Conventional — uses metal or plastic drill pipe of varying types • Coil tubing — uses a giant coil of tube and a downhole drilling motor By height (All rigs drill with only a single pipe. Rigs are differentiated by how many connected pipe they are able to "stand" in the derrick when needing to temporarily remove the drill pipe from the hole. Typically this is done when changing a drill bit or when "logging" the well.) • Single — can pull only single drill pipes. The presence or absence of vertical pipe racking "fingers" varies from rig to rig. • Double — can hold a stand of pipe in the derrick consisting of two connected drill pipes, called a "double stand". • Triple — can hold a stand of pipe in the derrick consisting of three connected drill pipes, called a "triple stand". By method of rotation or drilling method • No-rotation includes direct push rigs and most service rigs • Rotary table — rotation is achieved by turning a square or hexagonal pipe (the "Kelly") at drill floor level. • Top drive — rotation and circulation is done at the top of the drill string, on a motor that moves in a track along the derrick. • Sonic — uses primarily vibratory energy to advance the drill string • Hammer — uses rotation and percussive force. By position of derrick • Conventional — derrick is vertical • Slant — derrick is slanted at a 45 degree angle to facilitate horizontal drilling Drill types There are a variety of drill mechanisms which can be used to sink a borehole into the ground. Each has its advantages and disadvantages, in terms of the depth to which it can drill, the type of sample returned, the costs involved and penetration rates achieved. There are two basic types of drills: drills which produce rock chips, and drills which produce core samples. Auger drilling Auger drilling is done with a helical screw which is driven into the ground with rotation; the earth is lifted up the borehole by the blade of the screw. Hollow stem auger drilling is used for softer ground such as swamps where the hole will not stay open by itself for environmental drilling, geotechnical drilling, soil engineering and geochemistry reconnaissance work in exploration for mineral deposits. Solid flight augers/bucket augers are used in harder ground construction drilling. In some cases, mine shafts are dug with auger drills. Small augers can be mounted on the back of a utility truck, with large augers used for sinking piles for bridge foundations. Auger drilling is restricted to generally soft unconsolidated material or weak weathered rock. It is cheap and fast. Percussion rotary air blast drilling (RAB) RAB drilling is used most frequently in the mineral exploration industry. (This tool is also known as a Down-the-hole drill.) The drill uses a pneumatic reciprocating piston-driven "hammer" to energetically drive a heavy drill bit into the rock. The drill bit is hollow, solid steel and has ~20 mm thick tungsten rods protruding from the steel matrix as "buttons". The tungsten buttons are the cutting face of the bit. The cuttings are blown up the outside of the rods and collected at surface. Air or a combination of air and foam lift the cuttings. RAB drilling is used primarily for mineral exploration, water bore drilling and blast-hole drilling in mines, as well as for other applications such as engineering, etc. RAB produces lower quality samples because the cuttings are blown up the outside of the rods and can be contaminated from contact with other rocks. RAB drilling at extreme depth, if it encounters water, may rapidly clog the outside of the hole with debris, precluding removal of drill cuttings from the hole. This can be counteracted, however, with the use of "stabilisers" also known as "reamers", which are large cylindrical pieces of steel attached to the drill string, and made to perfectly fit the size of the hole being drilled. These have sets of rollers on the side, usually with tungsten buttons, that constantly break down cuttings being pushed upwards. The use of high-powered air compressors, which push 900-1150 cfm of air at 300-350 psi down the hole also ensures drilling of a deeper hole up to ~1250 m due to higher air pressure which pushes all rock cuttings and any water to the surface. This, of course, is all dependent on the density and weight of the rock being drilled, and on how worn the drill bit is. Air core drilling Air core drilling and related methods use hardened steel or tungsten blades to bore a hole into unconsolidated ground. The drill bit has three blades arranged around the bit head, which cut the unconsolidated ground. The rods are hollow and contain an inner tube which sits inside the hollow outer rod barrel. The drill cuttings are removed by injection of compressed air into the hole via the annular area between the innertube and the drill rod. The cuttings are then blown back to surface up the inner tube where they pass through the sample separating system and are collected if needed. Drilling continues with the addition of rods to the top of the drill string. Air core drilling can occasionally produce small chunks of cored rock. This method of drilling is used to drill the weathered regolith, as the drill rig and steel or tungsten blades cannot penetrate fresh rock. Where possible, air core drilling is preferred over RAB drilling as it provides a more representative sample. Air core drilling can achieve depths approaching 300 meters in good conditions. As the cuttings are removed inside the rods and are less prone to contamination compared to conventional drilling where the cuttings pass to the surface via outside return between the outside of the drill rod and the walls of the hole. This method is more costly and slower than RAB. Cable tool drilling Cable tool rigs are a traditional way of drilling water wells. The majority of large diameter water supply wells, especially deep wells completed in bedrock aquifers, were completed using this drilling method. Although this drilling method has largely been supplanted in recent years by other, faster drilling techniques, it is still the most practicable drilling method for large diameter, deep bedrock wells, and in widespread use for small rural water supply wells. The impact of the drill bit fractures the rock and in many shale rock situations increases the water flow into a well over rotary. Also known as ballistic well drilling and sometimes called "spudders", these rigs raise and drop a drill string with a heavy carbide tipped drilling bit that chisels through the rock by finely pulverizing the subsurface materials. The drill string is composed of the upper drill rods, a set of "jars" (inter-locking "sliders" that help transmit additional energy to the drill bit and assist in removing the bit if it is stuck) and the drill bit. During the drilling process, the drill string is periodically removed from the borehole and a bailer is lowered to collect the drill cuttings (rock fragments, soil, etc.). The bailer is a bucket-like tool with a trapdoor in the base. If the borehole is dry, water is added so that the drill cuttings will flow into the bailer. When lifted, the trapdoor closes and the cuttings are then raised and removed. Since the drill string must be raised and lowered to advance the boring, the casing (larger diameter outer piping) is typically used to hold back upper soil materials and stabilize the borehole.
Rig components
1) Power system 2) Rotary system 3) Circulating system 4) Hoisting system 5) Control system