Abstract In this paper, the problem of optimal assignment of trailer-mounted steam generators for cyclic steam stimulation CSS of petroleum wells is formulated as a parallel uniform machines scheduling PMS problem with release dates.
Description[ edit ] The SAGD process of heavy oil or bitumen production is an enhancement on the steam injection techniques originally developed to produce heavy oil from the Kern River Oil Field of California. The cyclic steam stimulation CSS process developed for the California heavy oil fields was able to produce oil from some portions of the Alberta oil sands, such as the Cold Lake oil sandsbut did not work as well to produce bitumen from heavier and deeper deposits in the Athabasca oil sands and Peace River oil sandswhere the majority of Alberta's oil sands reserves lie.
The upper well injects steam, and the lower one collects Css cyclic steam stimulation heated crude oil or bitumen that flows down due to gravity, plus recovered water from the condensation of the injected steam. The basis of the SAGD process is that thermal communication is established with the reservoir so that the injected steam forms a "steam chamber".
The heat from the steam reduces the viscosity of the heavy crude oil or bitumen which allows it to flow down into the lower wellbore. The steam and associated gas rise because of their low density compared to the heavy crude oil below, ensuring that steam is not produced at the lower production well, tend to rise in the steam chamber, filling the void space left by the oil.
Associated gas forms, to a certain extent, an insulating heat blanket above and around the steam. The condensed water and crude oil or bitumen is recovered to the surface by pumps such as progressive cavity pumps that work well for moving high-viscosity fluids with suspended solids.
The higher the liquid level above the producer the lower the temperature and higher is the sub-cool. However real life reservoirs are invariably heterogeneous therefore it becomes extremely difficult to achieve a uniform sub-cool along the entire horizontal length Css cyclic steam stimulation a well.
As a consequence many operators, when faced with uneven stunted steam chamber development, allow a small quantity of steam to enter into the producer to keep the bitumen in the entire wellbore hot hence keeping its viscosity low with the added benefit of transferring heat to colder parts of the reservoir along the wellbore.
Another variation sometimes called Partial SAGD is used when operators deliberately circulate steam in the producer following a long shut-in period or as a startup procedure. Though a high value of sub-cool is desirable from a thermal efficiency standpoint as it generally includes reduction of steam injection rates but it also results in slightly reduced production due to a corresponding higher viscosity and lower mobility of bitumen caused by lower temperature.
Another drawback of very high sub-cool is the possibility of steam pressure eventually not being enough to sustain steam chamber development above the injector, sometimes resulting in collapsed steam chambers where condensed steam floods the injector and precludes further development of the chamber.
The process is relatively insensitive to shale streaks and other vertical barriers to steam and fluid flow because, as the rock is heated, differential thermal expansion allows steam and fluids to gravity flow through to the production well.
Thermally, SAGD is generally twice as efficient as the older cyclic steam stimulation CSS process, and it results in far fewer wells being damaged by the high pressures associated with CSS.
Combined with the higher oil recovery rates achieved, this means that SAGD is much more economic than cyclic steam processes where the reservoir is reasonably thick.
He tested the concept with Imperial Oil inin a pilot at Cold Lake which featured one of the first horizontal wells in the industry, with vertical injectors. Its first facility was owned and operated by ten industrial participants and received ample government support Deutsch and McLennan  including from the Alberta Heritage Savings Trust Fund.
The concept coincided with development of directional drilling techniques that allowed companies to drill horizontal wells accurately, cheaply and efficiently, to the point that it became hard to justify drilling a conventional vertical well any more.
At Foster Creek Cenovus has employed its patented  'wedge well' technology to recover residual resources bypassed by regular SAGD operations, this improves the total recovery rate of the operation. The 'wedge well' technology works by accessing the residual bitumen that is bypassed in regular SAGD operations by drilling an infill well between two established operating SAGD well pairs once the SAGD steam chambers have matured to the point where they have merged and are in fluid communication and then what is left to recover in that reservoir area between the operating SAGD well pairs is a 'wedge' of residual, bypassed oil.
While traditional drilling methods were prevalent up until the s, high crude prices of the 21st Century are encouraging more unconventional methods such as SAGD to extract crude oil. The Canadian oil sands have many SAGD projects in progress, since this region is home of one of the largest deposits of bitumen in the world Canada and Venezuela have the world's largest deposits.
As ofthe oil sands reserves stand at around billion barrels. Oil and water nexus[ edit ] SAGD, a thermal recovery process, consumes large quantities of water and natural gas. As a specific example of an underlying data weakness, this figure excludes the increasingly important steam-assisted gravity drainage technique SAGD method.
We encourage future researchers to fill this hole.
Historically, natural gas has been used as a fuel for Canadian oil sands projects, due to the presence of large stranded gas reserves in the oil sands area. However, with the building of natural gas pipelines to outside markets in Canada and the United States, the price of gas has become an important consideration.
The fact that natural gas production in Canada has peaked and is now declining is also a problem. Other sources of generating heat are under consideration, notably gasification of the heavy fractions of the produced bitumen to produce syngasusing the nearby and massive deposits of coalor even building nuclear reactors to produce the heat.
Use of water for steam generation[ edit ] A source of large amounts of fresh and brackish water and large water re-cycling facilities are required in order to create the steam for the SAGD process.
Water is a popular topic for debate in regards to water use and management. As ofAmerican petroleum production not limited to SAGD generates over 5 billion gallons of produced water every day.
Traditionally close to 70 million cubic metres of the water volume that was used in the SAGD process was fresh, surface, water. There has been a significant reduction in fresh water use as ofwhen approximately 18 million cubic metres were used.
Though to offset the drastic reduction in fresh water use, industry has begun to significantly increase the volume of saline groundwater involved.2 SPEMS Cyclic Steam Stimulation (CSS) Cyclic steam stimulation, also called steam soak or huff and puff method, was discovered fortuitously in Venezuela in , by one of the steam injector wells backflowed to releive the reservoir pressure (Trebolle, Chalot, Colmenares, & Lagoven, ).
CYCLIC STEAM STIMULATION (CSS) A single well is drilled into the oil sands deposit. High pressure steam is injected into the reservoir to heat the bitumen and reduce its viscosity. This steam continues to be injected for several weeks in order to fully saturate the reservoir.
Use of Cyclic Steam Stimulation technique for Enhanced Oil Recovery Cyclic Steam Stimulation(CSS), also known as the steam huff and puff, steam soak, or cyclic steam injection is a process in which a combination of directional and horizontal wells are used to inject high pressure steam into the Clearwater Formation, which warms the bitumen oil viscosities(, cp) at reservoir.
Cyclic steam stimulation (CSS) has been widely applied as an effective technique for heavy oil reservoirs, but it is increasingly concerned in recent years for its limited oil recovery performance, low energy efficiency, high water consumption and great environmental footprints due to greenhouse gas emissions.
The hybrid injection of air and. Recent Cyclic Steam Stimulation Css Inquiries Cyclic Steam Stimulation Hi i am looking for the information on cyclic steam stimulation, an enhanced oil recovery method.
Steam injection is an increasingly common method of extracting heavy crude oil. It is considered an enhanced oil recovery (EOR) method and is the main type of thermal stimulation of oil reservoirs.
There are several different forms of the technology, with the two main ones being Cyclic Steam Stimulation and Steam rutadeltambor.com are most .