Monday, September 21, 2009
by ShoXee
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Flash Vaporization Flash Vaporization Occurs when the pressure confining mixture is reduced , Thereby permiting the mixture to partially vaporize Differential Vaporization Differential Vaporization is the process in which the gas is removed from the liquid as fast as it is for
by ShoXee
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Tubing and Casing connection. An oil field tubular connection is provided for joining metallic tubulars at a well site. At least one end of each tubular is provided with a frustoconical external sealing surface for metal-to-metal sealing engagement with a corresponding surface of an adjoining tubular. A plurality of antigalling grooves provided along the external sealing surface each project radially inward thereof and circumferentially encircle the threaded end of the tubular member and seal the groove from fluid communication with the interior of the tubular member. The antigalling grooves are particularly well suited for use with a low angular taper sealing surface of less than approximately 7 degree, and reduce galling between the metal sealing surfaces during makeup of the connection. Each tubular connection may also include an energizing groove spaced axially between the exterior sealing surface and the threads on the tubular member. The energizing groove receives excess thread lubricant, and has a uniform radial depth circumferentially about the tubular member for reducing the cross-sectional thickness of the tubular member, thereby allowing the exterior sealing surface to move radially outward in response to increased tubing pressure and allowing more flexibility for increased interference between the sealing surfaces during makeup of the connection. Type of tubing connection:- 1) External upset. External Upset Tubing. The external upset area near a tubing joint must achieve the structural integrity required to safely assemble the tubing string. In some cases, the upset area is used in handling the tubing string by providing a seat for the elevators. However, in many cases, special tubing elevators incorporating slips that engage on the external surface of the tubing wall are used to avoid excessive stresses in the tool-joint area. Non-Upset Tubing A non-upset tubing section, a tubular coupling, a connection for non-upset tubing sections, and a method for connecting the non-upset tubing section and the tubular coupling are disclosed. Methods for fabricating the non-upset tubing section and the tubular coupling are also disclosed. In one embodiment, the non-upset tubing section has an outer diameter of about 2 3/8 inches and, in another embodiment has an outer diameter of about 2 7/8 inches. The non-upset tubing section also has an externally tapered threaded surface having approximately eight rounded threads per linear inch. The tubular coupling has an outer diameter of about 2 7/8 inches, for use with at least one 2 3/8 inches OD tubing section, or about 3 1/2 inches, for use with at least one 2 7/8 inches OD tubing section. The coupling also has an internally tapered threaded surface having approximately eight rounded threads per linear inch and having a pitch diameter of about 2.258 inches for use with the 2 3/8 inches OD tubing section or about 2.729 inches for use with the 2 7/8 inches OD tubing section; Each pitch diameter is measured at a plane located about 1.250 inches from a plane located at a face of the coupling. To connect the non-upset tubing section with the tubular coupling, a thread compound is applied to either or both the threaded surface of the non-upset tubing section and the threaded surface of the tubular coupling. The non-upset tubing section is then inserted into one end of the coupling, and either the tubing section or the coupling is turned relative to its mating part until the non-upset tubing section and coupling reliably connect and seal. Flush Joint Tubing A type of tubing connection in which the internal or external surfaces are the same diameter throughout the tubing joint. Internal flush joints are most common, offering no restriction to fluid flow. Externally flush joints are typically used in more specialized applications, such as washover pipe for fishing operations, to allow adequate outer diameter (OD) clearance. The TPS-MULTISEAL FLUSH JOINT Tubing and Casing connection is a non upset two step integral joint, suitable for use as liners and moderate depth casing. Characteristics: -14° metal to metal internal pressure seal. Note: Some of the Flush Joint Tubing sometime is good for External sealing OD and internal sealing ID that the moving seal are can able to run thru without any interference on ID and OD but study with care is needed in the dimension. -Disadvantage of using Flush joint tubing is it has lower tensile strength as compare to other type of tubing joint.
2) Non-upset.
3) Flush Joint.
-30° metal to metal internal external pressure seal and torque shoulder.
-Completely flush OD and ID for maximum annular and running clearances.
-Pin and Box threads machined directly into pipe wall, no coupling required.
-Damaged threads can be simply cut off and remachined.
-Two step non tapered buttress type thread form.
-No thread intererence, so no tendency to thread galling.
-Stable two thread flank stabbing.
-Cannot be cross threaded.
-Fast make up.
-Integral connection halves the number of threaded connections (no mill connection).
-External pressure integrity in excess of pipe body.
-Repeatable sealing capability on multiple make and breaks.
-Not for Hanging heavy hange weight, if really needed then the Well completion engineer have to be assure on the maximum hanging weight and the tensile strength of tubing joint.
-it normally come with thin wall.
by ShoXee
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Type of crude Oil. Sweet crude oil is a type of petroleum. The adjective sweet refers to small amounts of hydrogen sulfide and carbon dioxide; sweet crude generally contains less than 0.5% sulfur. This high quality, low sulfur crude oil is commonly used for processing into gasoline and is in high demand, particularly in the United States and China. Producers of sweet crude oil include: Saudi Arabia Brent Crude is one of the major classifications of oil consisting of Brent Crude, Brent Sweet Light Crude, Oseberg and Forties. Brent Crude is sourced from the North Sea. Typical price difference per barrel is about $1 less than WTI, and $1 more than OPEC Basket. Sour crude oil contains the impurities hydrogen sulfide (H2S) and carbon dioxide, or mercaptans. All crude oil contains some impurities. When the total sulfide level in the oil is > 1 % the oil is called "sour". The impurities will need to be removed before this lower quality crude can be refined into gasoline, thereby increasing the cost of processing. This results in a higher-priced gasoline than one made from sweet crude oil. Thus sour crude is usually processed into heavy oil such as diesel rather than gasoline to reduce processing cost. Sour oil is toxic and corrosive, with high levels of hydrogen sulfide. The oil has the smell of rotten eggs, and at high concentrations the inhalation of hydrogen sulfide is fatal. Venezuela is a major producer of sour crude oil. API degree A hydrometer scale used to measure the density of petroleum, established by the American Petroleum Institute. Symbol, °API. where “G” stands for the specific gravity of the liquid at 60°F in relation to water at 60°F. Reference:- API gravity is a specific gravity scale developed by the American Petroleum Institute (API) for measuring the relative density of various petroleum liquids. API gravity is graduated in degrees on a hydrometer instrument and was designed so that most values would fall between 10 and 70 API gravity degrees. History of development:- The U.S. National Bureau of Standards in 1916 established the Baumé scale (see degrees Baumé) as the standard for measuring specific gravity of liquids less dense than water. Investigation by the U.S. National Academy of Sciences found major errors in salinity and temperature controls that had caused serious variations in published values. Hydrometers in the U.S. had been manufactured and distributed widely with a modulus of 141.5 instead of the Baumé scale modulus of 140. The scale was so firmly established that by 1921 the remedy implemented by the American Petroleum Institute was to create the API Gravity scale recognizing the scale that was actually being used. The formula used to obtain the API gravity of petroleum liquids is thus: (See ASTM D1298) Classifications or grades:- Generally speaking higher API gravity degree oil values have a greater commercial value and lower degree values have lower commercial value. This general rule only holds up to 45 degrees API gravity as beyond this value the molecular chains become shorter and less valuable to a refinery. Crude oil is classified as light, medium or heavy, according to its measured API gravity. Medium oil is defined as having an API gravity between 22.3 °API and 31.1 °API Heavy oil is defined as having an API gravity below 22.3 °API. Oil which will not flow at normal temperatures or without dilution is named bitumen and the API gravity is generally less than 10 °API. Bitumen derived from the oil sands deposits in the Alberta, Canada area has an API gravity of around 8 °API. It is 'upgraded' to an API gravity of 31 °API to 33 °API and the upgraded oil is known as synthetic oil. American Petroleum Institute-API The American Petroleum Institute, commonly referred to as API, is the main U.S. trade association for the oil and natural gas industry, representing about 400 corporate members involved in all aspects of the industry. API is involved in lobbying and government liaison on behalf of the American oil and natural gas industries. It takes positions on access, exploration, taxes, trade regulation, environmental regulation, fuels, industry security and climate change. API also distributes more than 200,000 copies of its publications each year. The publications, technical standards, and electronic and online products are designed to help users improve the efficiency and cost-effectiveness of their operations, comply with legislative and regulatory requirements, and safeguard health, ensure safety, and protect the environment. Each publication is overseen by a committee of leading industry professionals. API's publications are developed by member company engineers and other professionals. For example, API 610 is the specification for centrifugal pumps, API 682 governs mechanical seals, and API 677 is the standard for gear units. API also defines the industry standard for the energy conservation of motor oil. SM is the latest specification to which motor oils should adhere since 2004. API provides vessel codes and standards for the design and fabrication of pressure vessels that help safeguard the lives of people and environments all over the world. YRC.
Romania
Sudan
United Kingdom (Brent Crude)
United States (West Texas Intermediate)
Oman
Yemen
Nigeria
Malaysia
Canada
Indonesia
The name 'Brent' comes from the formation layers - Broom, Rannoch, Etieve, Ness and TarbatOil production from Europe, Africa and the Middle East flowing West tends to be priced relative to this oil, i.e. it forms a benchmark. Brent blend is a light crude oil, though not as light as West Texas Intermediate (WTI). It contains approximately 0.37% of sulfur, classifying it as sweet crude, yet again not as sweet as WTI. Brent is ideal for production of gasoline and middle distillates. It is typically refined in Northwest Europe, but when the market prices are favorable for export, it can be refined also in East or Gulf Coast of the United States or the Mediterranean region.
Brent Crude has an API gravity of around 38.6.
When the U.S. Bureau of Standards standardized the Baumé hydrometer scale, it was “discovered that most of the hydrometers in use in the American petroleum industry had been erroneously manufactured to a modulus of 141.5 rather than 140. By 1921 this condition had become so firmly entrenched that the only seeming remedy was to recognize the scale in predominate use and rename it.”
-VOLUME CONVERSION
API gravity formulas:-
API gravity = (141.5/SG at 60 °F) - 131.5
Conversely, the specific gravity of petroleum liquids can be derived from the API gravity value as SG at 60 °F = 141.5/(API gravity + 131.5) 60°F (or 15 5/9 °C) is used as the normal value for measurements and further tables give adjustments for temperature.
Thus, a heavy oil with a specific gravity of 1.0 (i.e., with the same density as pure water at 60°F) would have an API gravity of: (141.5/1.0) - 131.5 = 10.0 degrees API.
Light crude oil is defined as having an API gravity higher than 31.1 °API
API's current policy is that emissions from the production and use of oil and natural gas may be contributing to global warming by enhancing the atmosphere's natural greenhouse effect. API coordinates voluntary industry efforts to reduce emissions through technology and improved operational efficiency. API also believes the contribution of possible man-made warming is uncertain as are the extent and timing of potential future impacts. Previously, the API was active in organizing opposition to laws and regulations that would limit smokestack and tailpipe pollution and reduce carbon dioxide emissions. The API was also active in public relations efforts that claim that the greenhouse effect and global warming in general will be beneficial to society, and that the scientific consensus on the dangers of global warming are incorrect.
API University is API’s comprehensive continuing education program for oil and natural gas professionals, in part on-line, such as the interactive computer-based training course "Basic Principles of Petroleum".
by ShoXee
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An oil well is a term for any perforation through the Earth's surface designed to find and release both petroleum oil and gas hydrocarbons. History The earliest oil wells were drilled percussively by hammering a cable tool into the earth. Soon after, cable tools were replaced with rotary drilling, which could drill boreholes to much greater depths and in less time. Modern wells drilled using rotary drills can achieve lengths of over 12 000 meters (38,000 feet). Until the 1970s, most oil wells were vertical (although different lithology and mechanical imperfections cause most wells to deviate at least slightly from true vertical). However, modern directional drilling technologies allow for strongly deviated wells which can, given sufficient depth and with the proper tools, actually become horizontal. This is of great value as the reservoir rocks which contain hydrocarbons are usually horizontal, or sub-horizontal; a horizontal wellbore placed in a production zone has more surface area in the production zone than a vertical well, resulting in a higher production rate. The use of deviated and horizontal drilling has also made it possible to reach reservoirs several kilometers or miles away from the drilling location (extended reach drilling), allowing for the production of hydrocarbons located below locations that are either difficult to place a drilling rig on, is environmentally sensitive, or is populated Life of a Well The creation and life of a well can be divided up into five segments: Planning Drilling Completion Production Abandonment Drilling The well is created by drilling a hole 5 to 30 inches (13–76 cm) wide into the earth with an oil rig which rotates a drill bit. After the hole is drilled, a steel pipe (casing) slightly smaller than the hole size is placed the hole, and is secured in the hole with cement. The casing provides structural integrity to the newly drilled wellbore in addition to isolating potentially dangerous high pressure zones from each other and from the surface. Drilling fluid (aka "mud") is pumped down the inside of the drill pipe and exits at the drill bit and aids to break up the rock, keeping pressure on top of the bit, as well as clean, cool and lubricate the bit. The generated rock "cuttings" are swept up by the drilling fluid as it circulates back to surface outside the drill pipe. Then go over "shakers" which shakes out the cuttings over screens allowing the good fluid to return back into the pits. Watching for abnormalities in the returning cuttings and volume of returning fluid are imperative to catch "kicks" (when the pressure below the bit is more so than above causing gas and mud to come back up uncontrollably) early. The pipe or drill string to which the bit is attached is gradually lengthened as the well gets deeper by screwing in several 30-foot (10 m) joints of pipe at surface. Usually joints are combined into 3 joints equaling 1 stand. Some smaller rigs only use 2 joints and newer rigs can handle stands of 4 joints. This process is all facilitated by a drilling rig which contains all necessary equipment to circulate the drilling fluid, hoist and turn the pipe, control downhole pressures, remove cuttings from the drilling fluid, and generate onsite power for these operations. Completion After drilling and casing the well, it must be 'completed'. Completion is the process in which the well is enabled to produce oil or gas. Enhanced recovery methods such as waterflooding, steam flooding, or CO2 flooding may be used to increase reservoir pressure and provide a "sweep" effect to push hydrocarbons out of the reservoir. Such methods require the use of injection wells (often picked from old production wells in a carefully determined pattern), and are used when facing problems with reservoir pressure depletion, high oil viscosity, or can even be employed early in a field's life; in certain cases – depending on the reservoir's geomechanics – reservoir engineers may determine that ultimate recoverable oil may be increased by applying a waterflooding strategy early in the field's development rather than later. The application of such enhanced recovery techniques is often termed as "tertiary recovery" in the industry. Abandonment Finally, when the well no longer produces or produces so poorly that it is a liability to its owner, it is abandoned. In this simple process the wellbore is filled with cement so that the flowpath from the reservoir to the surface is plugged. Types of wells Oil wells come in many varieties. By produced fluid, there can be wells that produce oil, wells that produce oil and natural gas, or wells that only produce natural gas. Natural gas is almost always a byproduct of producing oil, since the small, light gas carbon chains come out of solution as it undergoes pressure reduction from the reservoir to the surface. Unwanted natural gas can actually be quite a disposal problem at the well site. If there is not a market for natural gas near the wellhead it is virtually valueless since it must be piped to the end user. Until recently, such unwanted gas was burned off at the wellsite, but due to environmental concerns this practice is becoming less and less common. Often, unwanted (or 'stranded'; gas without a market) gas is pumped back into the reservoir with an 'injection' well for disposal or repressurizing the producing formation. Another solution is to export the natural gas as a liquid. Of course, in locations such as the United States with a high natural gas demand, pipelines are constructed to take the gas from the wellsite to the end consumer. Another obvious way to classify oil wells is by land or offshore wells. There really is very little difference in the well itself; an offshore well simply targets a reservoir that also happens to be underneath an ocean. Also, due to logistics, drilling an offshore well is far more costly than an onshore well. By far the most common type of well is of the onshore variety. These wells dot the Southwestern United States, and are also the most common type of well in the Middle East. Another way to classify oil wells is by their purpose in contributing to the development of a resource. They can be characterized as: production wells when they are drilled primarily for producing oil or gas, once the producing structure and characteristics are established. appraisal wells when they are used to assess characteristics (such as flowrate) of a proven hydrocarbon accumulation. exploration wells when they are drilled purely for exploratory (information gathering) purposes in a new area. wildcat wells when a well is drilled, based on a large element of hope, in a frontier area where very little is known about the subsurface. In the early days of oil exploration in Texas, wildcats were common as productive areas were not yet established. In modern times, oil exploration in many areas has reached a very mature phase and the chances of finding oil simply by drilling at random are very low. Therefore, a lot more effort is placed in exploration and appraisal wells.
With these zones safely isolated and the formation protected by the casing, the well can be drilled deeper (into potentially more-unstable and violent formations) with a smaller bit, and also cased with a smaller size casing. Modern wells often have 2-5 sets of subsequently smaller hole sizes drilled inside one another, each cemented with casing.
To drill the well,
The drill bit, aided by rotary torque and the compressive weight of drill collars above it, breaks up the earth.
In a cased-hole completion, small holes called perforations are made in the portion of the casing which passed through the production zone, to provide a path for the oil to flow from the surrounding rock into the production tubing. In open hole completion, often 'sand screens' or a 'gravel pack' is installed in the last drilled, uncased reservoir section. These maintain structural integrity of the wellbore in the absence of casing, while still allowing flow from the reservoir into the wellbore. Screens also control the migration of formation sands into production tubulars and surface equipment, which can cause washouts and other problems, particularly from unconsolidated sand formations in offshore fields.
After a flow path is made, acids and fracturing fluids are pumped into the well to fracture, clean, or otherwise prepare and stimulate the reservoir rock to optimally produce hydrocarbons into the wellbore. Finally, the area above the reservoir section of the well is packed off inside the casing, and connected to the surface via a smaller diameter pipe called tubing. This arrangement provides a redundant barrier to leaks of hydrocarbons as well as allowing damaged sections to be replaced. Also, the smaller diameter of the tubing produces hydrocarbons at an increased velocity in order to overcome the hydrostatic effects of heavy fluids such as water.
In many wells, the natural pressure of the subsurface reservoir is high enough for the oil or gas to flow to the surface. However, this is not always the case, especially in depleted fields where the pressures have been lowered by other producing wells, or in low permeability oil reservoirs. Installing a smaller diameter tubing may be enough to help the production, but artificial lift methods may also be needed. Common solutions include downhole pumps, gas lift, or surface pump-jacks (e.g., the "nodding donkey" pumps dotting the countryside in old oil fields in Texas and Oklahoma). The use of artificial lift technology in a field is often termed as "secondary recovery" in the industry.
Production
The production stage is the most important stage of a well's life, when the oil and gas are produced. By this time, the oil rigs and workover rigs used to drill and complete the well have moved off the wellbore, and the top is usually outfitted with a collection of valves called a "Christmas Tree". These valves regulate pressures, control flows, and allow access to the wellbore in case further completion work needs to be performed. From the outlet valve of the Christmas Tree, the flow can be connected to a distribution network of pipelines and tanks to supply the product to refineries, natural gas compressor stations, or oil export terminals.
As long as the pressure in the reservoir remains high enough, this Christmas Tree is all that is required to produce the well. If the pressure depletes and it is considered economically viable, an artificial lift method mentioned in the completions section can be employed.
Workovers are often necessary in older wells, which may need smaller diameter tubing, scale or parrafin removal, repeated acid matrix jobs, or even completing new zones of interest in a shallower reservoir. Such remedial work can be performed using workover rigs – also known as pulling units – to pull and replace tubing, or by the use of a well intervention technique called coiled tubing.
by ShoXee
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The GAS HYDRATES A gas hydrate is a crystalline solid; its building blocks consist of a gas molecule surrounded by a cage of water molecules. Thus it is similar to ice, except that the crystalline structure is stabilized by the guest gas molecule within the cage of water molecules. Many gases have molecular sizes suitable to form hydrate, including such naturally occurring gases as carbon dioxide, hydrogen sulfide, and several low-carbon-number hydrocarbons, but most marine gas hydrates that have been analyzed are methane hydrates. Gas Hydrates will be the coming future generation new source of energy. Clathrate hydrates (or alternatively gas clathrates, gas hydrates, clathrates, hydrates etc) are a class of solids in which gas molecules occupy "cages" made up of hydrogen-bonded water molecules. These "cages" are unstable when empty, collapsing into conventional ice crystal structure, but they are stabilized by the inclusion of appropriately sized molecules within them. Most low molecular weight gases (including O2, H2, N2, CO2, CH4, H2S, Ar, Kr, and Xe), as well as some higher hydrocarbons and freons will form hydrate under certain pressure-temperature conditions. Clathrate hydrates are not chemical compounds. The formation and decomposition of clathrate hydrates are first order phase transitions, not chemical reactions. Clathrates are believed to occur in large quantities on some outer planets, moons and trans-Neptunian objects, binding gas at fairly high temperatures. Clathrates have also been discovered in large quantity on Earth, e.g. in giant natural methane clathrate deposits on the deep ocean floor (e.g. in the northern headwall flank of the Storegga Slide, which is a part of the Norwegian continental shelf) and in permafrost regions (e.g. the Mallik gas hydrate field in the Mackenzie Delta of northwestern Canadian Arctic). Hydrocarbon clathrates are a problem for the petroleum industry, since their formation inside gas pipelines frequently leads to plug formation in the latter. Deep sea deposition of carbon dioxide clathrate to remove this greenhouse gas from the atmosphere has also been proposed. Gas hydrates are created when water and gas combine to form a crystalline substance that looks like ice. This occurs when excess methane is present, and when temperature and pressure conditions are suitable. Gas hydrates are common in marine sediments along the margins of continents, where the methane originates from the decomposition of living things. Off the Oregon coast, the Juan de Fuca plate slides beneath the North American plate in a process called subduction. As subduction occurs, sediments are scraped off the Juan de Fuca plate and form ridges on the edge of the North American plate. This process leads to formation of gas hydrates. Natural deposits Worldwide distribution of confirmed or inferred offshore gas hydrate-bearing sediments. Last edited by tahir ali (2009-09-06 09:30:39)
