الرمال النفطية

(تم التحويل من Oil sands)

الرمال النفطية Oil sands، أو تقنياً الرمال البتيومينية bituminous sands، هي نوع من ترسب غير معتاد للپترول. والرمال النفطية هي إما رمال سائبة أو حجر رملي متماسك جزئياً ويحتوي تواجد طبيعي لخليط من الرمل والطمي والماء ومشبع بصيغة كثيفة وشديدة اللزوجة من الپترول يشار غليها تقنياً بإسم بتيومين (أو بالعامية: قار بسبب مظهرها المشابه سطحياً).[1][2]

ترسبات البتيومين الطبيعية توجد في العديد من الدول، ولكن تتواجد بالخصوص بكميات هائلة في كندا.[3][4] وثمة احتياطيات كبيرة أخرى في قزخستان وروسيا. ترسبات النفط حول العالم تُقدّر بما يزيد عن 2 trillion barrels (320 billion cubic metres)؛[5] التقديرات تضم ترسبات لم تُكتشف بعد. الاحتياطيات المؤكدة من القار تضم نحو 100 بليون برميل،[6] وإجمالي احتياطيات القار تـُقدر بحوالي 249.67 Gbbl (39.694×10^9 m3) حول العالم، منها 176.8 Gbbl (28.11×10^9 m3)، أو 70.8%، هي في ألبرتا، كندا.[3]

تم اعتبار احتياطيات الرمال النفطية مؤخرًا فقط[when?] جزءًا من احتياطيات النفط في العالم، حيث يتيح ارتفاع أسعار النفط والتكنولوجيا الجديدة استخراج ومعالجة مربحة. غالبًا ما يُشار إلى الزيت المنتج من رمال القار بـ زيت غير تقليدي أو القار الخام ، لتمييزه عن الهيدروكربونات السائلة المنتجة من آبار النفط التقليدية.

يصف مجلس الطاقة الوطني الكندي البيتومين الخام الموجود في رمال النفط الكندية بأنه "مزيج عالي اللزوجة من الهيدروكربونات أثقل من الپنتان والذي، في حالته الطبيعية، لا يمكن استرداده عادة عند معدل تجاري من خلال البئر لأنه أكثف من أن يتدفق".[7] القار الخام هو شكل سميك ولزج من النفط الخام ، ثقيل جدًا ولزج (سميك) بحيث لا يتدفق إلا إذا تم تسخينه أو تخفيفه بهيدروكربونات أخف مثل النفط الخام الخفيف أو مكثف الغاز الطبيعي. في درجة حرارة الغرفة، تشبه إلى حد كبير مولاس بارد.[8] يعرِّف مجلس الطاقة العالمي (WEC) البتيومين الطبيعي بأنه "زيت له لزوجة أكبر من 10,000 سنتي‌پواز تحت ظروف الخزان و API gravity أقل من 10° API".[9] حزام أورينوكو في ڤنزويلا يوصف أحياناً بأنه رمال نفطية، ولكن تلك الترسبات هي غير بتيومينية، مما يجعلها في تصنيف نفط خام ثقيل أو ثقيل جداً بسبب لزوجته المنخفضة.[10] يختلف البيتومين الطبيعي والزيت الثقيل للغاية في الدرجة التي تحلل بها من الزيوت التقليدية الأصلية بواسطة البكتيريا. ووفقًا لمركز WEC ، فإن النفط الثقيل لديه "جاذبية أقل من 10 درجات API ولزوجة الخزان لا تزيد عن 10000 سنتي‌پواز".[9]

حسب الدراسة التي أمرت بها حكومة ألبرتا وقامت بها مجموعة جيكوبس الهندسية، فإن الانبعاثات من خام الزيت-رمل تكون 12% أعلى من النفط الاعتيادي.[11]

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التاريخ

يعود استغلال رواسب البيتومين و seeps إلى أزمنة العصر الحجري القديم.[12] The earliest known use of bitumen was by Neanderthals, some 40,000 years ago. Bitumen has been found adhering to stone tools used by Neanderthals at sites in Syria. After the arrival of Homo sapiens, humans used bitumen for construction of buildings and waterproofing of reed boats, among other uses. In ancient Egypt, the use of bitumen was important in preparing Egyptian mummies.[13]

في الأزمنة القديمة، كان البتيومين أساساً سلعة في بلاد الرافدين يستخدمها السومريون والبابليون, although it was also found in the Levant and Persia. The area along the Tigris and Euphrates rivers was littered with hundreds of pure bitumen seepages. The Mesopotamians used the bitumen for waterproofing boats and buildings. In Europe, they were extensively mined near the French city of Pechelbronn, where the vapour separation process was in use in 1742.[14][15]


الجيولوجيا

The world's largest oil sands are in Venezuela and Canada. The geology of the deposits in the two countries is generally rather similar. They are vast heavy oil, extra-heavy oil, and/or bitumen deposits with oil heavier than 20°API, found largely in unconsolidated sandstones with similar properties. "Unconsolidated" in this context means that the sands have high porosity, no significant cohesion, and a tensile strength close to zero. The sands are saturated with oil which has prevented them from consolidating into hard sandstone.[16]

حجم المصادر

The magnitude of the resources in the two countries is on the order of 3.5 to 4 trillion barrels (550 to 650 billion cubic metres) of original oil in place (OOIP). Oil in place is not necessarily oil reserves, and the amount that can be produced depends on technological evolution. Rapid technological developments in Canada in the 1985-2000 period resulted in techniques such as steam-assisted gravity drainage (SAGD) that can recover a much greater percentage of the OOIP than conventional methods. The Alberta government estimates that with current technology, 10% of its bitumen and heavy oil can be recovered, which would give it about 200 billion barrels (32 billion m3) of recoverable oil reserves. Venezuela estimates its recoverable oil at 267 billion barrels (42 billion m3).[16] This places Canada and Venezuela in the same league as Saudi Arabia, having the three largest oil reserves in the world.

الترسبات الكبرى

There are numerous deposits of oil sands in the world, but the biggest and most important are in كندا وڤنزويلا، with lesser deposits in قزخستان وروسيا. The total volume of non-conventional oil in the oil sands of these countries exceeds the reserves of conventional oil in all other countries combined. Vast deposits of bitumen - over 350 billion cubic metres (2.2 trillion barrels) of oil in place - exist in the Canadian provinces of Alberta and Saskatchewan. If only 30% of this oil could be extracted, it could supply the entire needs of North America for over 100 years. These deposits represent plentiful oil, but not cheap oil. They require advanced technology to extract the oil and transport it to oil refineries.[17]

كندا

The oil sands of the Western Canadian Sedimentary Basin (WCSB) were formed as a result of the formation of the Canadian Rocky Mountains by the Pacific Plate overthrusting over the North American Plate as it pushed in from the west, carrying the formerly large island chains which now compose most of British Columbia. The collision compressed the Alberta plains and raised the Rockies over the plains, forming the Canadian Rockies. This mountain building process buried the sedimentary rock layers which underlie most of Alberta very deep, creating high subsurface temperatures, and producing a giant pressure cooker that converted the kerogen in the deeply buried organic-rich shales to light oil and natural gas.[16][18] These source rocks were similar to the American so-called oil shales, except the latter have never been buried deep enough to convert the kerogen in them into liquid oil.


أتاباسكا
مدينة فورت مكمري على ضفاف نهر أتاباسكا

رمال أتاباسكا النفطية تقع على طول نهر أتاباسكا وهي أكبر ترسبات قار في العالم، وتضم نحو 80% من إجمالي قار ألبرتا، والوحيد المناسب للتعدين السطحي. وبتكنولوجيا انتاج النفط الحديثة غير التقليدية، فعلى الأقل 10% من تلك الاحتياطيات، أو نحو 170 Gbbl (27×10^9 m3) تُعتبر قابلة للاستخراج اقتصادياً، مما يجعل إجمالي الاحتياطي المحقق لكندا هو ثالث أكبر احتياطي محقق في العالم، بعد النفط التقليدي السعودي و رمال أورينوكو النفطية الڤنزويلية.

كولد ليك
كولد ليك كما تبدو من Meadow Lake Provincial Park، ساسكاتشوان.

رمال كولد ليك النفطية تقع شمال شرق عاصمة ألبرتا، إدمونتون، بالقرب من الحدود مع ساسكاتشوان. A small portion of the Cold Lake deposit تقع في ساسكاتشوان. Although smaller than the Athabasca oil sands, the Cold Lake oil sands are important because some of the oil is fluid enough to be extracted by conventional methods. The Cold Lake bitumen contains more alkanes and less asphaltenes than the other major Alberta oil sands and the oil is more fluid.[19] ونتيجةً لذلك، فإن حث البخار الحلقي cyclic steam stimulation ‏(CSS) يشيع استخدامه في الانتاج.

ڤنزويلا

The Eastern Venezuelan Basin has a structure similar to the WCSB, but on a shorter scale. The distance the oil has migrated up-dip from the Sierra Orientale mountain front to the Orinoco oil sands where it pinches out against the igneous rocks of the Guyana Shield is only about 200 to 300 km (100 to 200 mi). The hydrodynamic conditions of oil transport were similar, source rocks buried deep by the rise of the mountains of the Sierra Orientale produced light oil that moved up-dip toward the south until it was gradually immobilized by the viscosity increase caused by biodgradation near the surface. The Orinoco deposits are early Tertiary (50 to 60 million years old) sand-silt-shale sequences overlain by continuous thick shales, much like the Canadian deposits.

In Venezuela, the Orinoco Belt oil sands range from 350 to 1,000 m (1,000 to 3,000 ft) deep and no surface outcrops exist. The deposit is about 500 km (300 mi) long east-to-west and 50 to 60 km (30 to 40 mi) wide north-to-south, much less than the combined area covered by the Canadian deposits. In general, the Canadian deposits are found over a much wider area, have a broader range of properties, and have a broader range of reservoir types than the Venezuelan ones, but the geological structures and mechanisms involved are similar. The main differences is that the oil in the sands in Venezuela is less viscous than in Canada, allowing some of it to be produced by conventional drilling techniques, but none of it approaches the surface as in Canada, meaning none of it can be produced using surface mining. The Canadian deposits will almost all have to be produced by mining or using new non-conventional techniques.

أورينوكو
پانوراما نهر أورينوكو.

حزام أورينوكو هو أرض في القطاع الجنوبي من الحوض الشرقي لـنهر أورينوكو في ڤنزويلا الذي يرقد على أكبر ترسب للبترول في العالم. ويتبع حزام أورينوكو مسار النهر. ويبلغ وسعه نحو 600 كم من الشرق إلى الغرب، و 70 كم من الشمال إلى الجنوب، بمساحة تناهز 55,314 كم².


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ترسبات أخرى

بالاضافة للمواقع الثلاثة الكندية الرئيسية للرمال النفطية في ألبرتا، فثمة ترسب رئيسي رابع للرمال النفطية في كندا، وهو الرمال النفطية في جزيرة ملڤل في الجزر القطبية الكندية، إلا أنها نائية جداً لأن نتوقع انتاجاً اقتصاديا في المستقبل المنظور.

الانتاج

Bituminous sands are a major source of unconventional oil, although only Canada has a large-scale commercial oil sands industry. In 2006, bitumen production in Canada averaged 1.25 Mbbl/d (200,000 m3/d) through 81 oil sands projects. 44% of Canadian oil production in 2007 was from oil sands.[20] This proportion is expected to increase in coming decades as bitumen production grows while conventional oil production declines, although due to the 2008 economic downturn work on new projects has been deferred.[4] Petroleum is not produced from oil sands on a significant level in other countries.[21]

التعدين السطحي

Mining operations in the Athabasca oil sands. NASA Earth Observatory image, 2009.

The Athabasca oil sands are the only major oil sands deposits which are shallow enough to surface mine. In the Athabasca sands there are very large amounts of bitumen covered by little overburden, making surface mining the most efficient method of extracting it. The overburden consists of water-laden muskeg (peat bog) over top of clay and barren sand. The oil sands themselves are typically 40 to 60 metres (130 to 200 ft) thick deposits of crude bitumen embedded in unconsolidated sandstone, sitting on top of flat limestone rock. Since Great Canadian Oil Sands (now Suncor Energy) started operation of the first large-scale oil sands mine in 1967, bitumen has been extracted on a commercial scale and the volume has grown at a steady rate ever since.

Oil sands tailings ponds

مقال رئيسي: Oil sands tailings ponds
Syncrude's Mildred Lake site, plant and tailings ponds Fort McMurray, Alberta


التكرير

Heavy crude oil feedstock#crude feedstock needs pre-processing before it is fit for conventional refineries, although heavy oil and bitumen refineries can do the pre-processing themselves. This pre-processing is called 'upgrading', the key components of which are as follows:

  1. removal of water, sand, physical waste, and lighter products
  2. catalytic purification by hydrodemetallisation (HDM), hydrodesulfurization (HDS) and hydrodenitrogenation (HDN)
  3. hydrogenation through carbon rejection or catalytic hydrocracking (HCR)

As carbon rejection is very inefficient and wasteful in most cases, catalytic hydrocracking is preferred in most cases. All these processes take large amounts of energy and water, while emitting more carbon dioxide than conventional oil.

Catalytic purification and hydrocracking are together known as hydroprocessing. The big challenge in hydroprocessing is to deal with the impurities found in heavy crude, as they poison the catalysts over time. Many efforts have been made to deal with this to ensure high activity and long life of a catalyst. Catalyst materials and pore size distributions are key parameters that need to be optimized to deal with this challenge and varies from place to place, depending on the kind of feedstock present.[22]

ألبرتا

There are four major oil refineries in Alberta which supply most of Western Canada with petroleum products, but as of 2012 these processed less than 1/4 of the approximately 1,900,000 bbl/d (300,000 m3/d) of bitumen and SCO produced in Alberta. Some of the large oil sands upgraders also produced diesel fuel as part of their operations. Some of the oil sands bitumen and SCO went to refineries other provinces, but most of it was exported to the United States. The four major Alberta refineries are:[23]

The $8.5-billion Sturgeon Refinery, a fifth major Alberta refinery, is under construction near Fort Saskatchewan with a completion date of 2017.[24][25] The proponents are Alberta Petroleum Marketing Commission, Canadian Natural Resources Limited and North West Upgrading Inc. NWU, which was founded in 2004, is a private, Alberta-based company with headquarters in Calgary.[25] Canadian Natural Resources Limited 50/50 entered into a joint venture partnership with NWU in February 2011[25] forming North West Redwater Partnership. This is the first oil refinery to be constructed in Alberta in thirty years - the last was Shell’s Scotford refinery which was completed in 1984.[24][26] The Sturgeon Refinery is the "first new refinery to be built with a carbon capture and storage system."[27] The plant is designed to convert up to 150,000 bbl/d (24,000 m3/d) of crude bitumen directly to diesel fuel. "In addition to producing ultra low-sulphur diesel and naphtha, the project will capture carbon dioxide which will be sold to Enhance Energy’s Alberta Carbon Trunk Line for use in enhanced oil recovery."[24] The refinery will process bitumen into diesel fuel not SCO so it is more of an upgrader than a refinery. A petroleum coker is required to upgrade the raw product before it can be made into diesel."[27]

By June 2014 the estimated cost of construction had increased from $5.7 billion to $8.5 billion[24] – or $170,000 per barrel of new capacity.[27]

انظر أيضاً

الهامش

  1. ^ "What Is Bitumen(Asphalt)?". Bitumena. Retrieved 2016-06-05.
  2. ^ Suryakanta. "15+ differences between bitumen and tar used in road construction". CivilBlog.org. Retrieved 2016-06-05.
  3. ^ أ ب خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة wec
  4. ^ أ ب "Alberta's Oil Sands: Opportunity, Balance" (PDF). Government of Alberta. March 2008. ISBN 978-0-7785-7348-7. Retrieved 13 May 2008. {{cite journal}}: Cite journal requires |journal= (help)
  5. ^ "About Tar Sands".
  6. ^ "Bitumen and heavy crudes: The energy security problem solved?". Oil and Energy Trends. 31 (6): 3–5. 2006. doi:10.1111/j.1744-7992.2006.310603.x.
  7. ^ "Canada's Energy Future: Energy Supply and Demand Projections to 2035 - Energy Market Assessment". National Energy Board of Canada. March 2014. Retrieved 26 March 2014.
  8. ^ "What Are The Oil Sands?". Canada’s Oil Sands. Calgary, AL: Canadian Association of Petroleum Producers. Retrieved 28 Feb 2016. Oil sands are a mixture of sand, water, clay and bitumen. Bitumen is oil that is too heavy or thick to flow or be pumped without being diluted or heated. *** Bitumen is so viscous that at room temperature it acts much like cold molasses.
  9. ^ أ ب Attanasi, Emil D.; Meyer, Richard F. (2010). "Natural Bitumen and Extra-Heavy Oil". Survey of energy resources (PDF) (22 ed.). World Energy Council. pp. 123–140. ISBN 0-946121-26-5.
  10. ^ Dusseault, M. B. (12–14 June 2001). "Comparing Venezuelan and Canadian heavy oil and tar sands" (PDF). Proceedings of Petroleum Society's Canadian International Conference. 2001–061: 20p.
  11. ^ Lewis, Barbara; Ljunggren, David; Jones, Jeffrey (10 May 2012). "Canada's oil sand battle with Europe". Reuters. Retrieved 2014-06-08.
  12. ^ Bilkadi, Zayn (November–December 1984). "Bitumen – A History". Saudi Aramco World. pp. 2–9. Retrieved 1 January 2011.
  13. ^ Hirst, K. Kris (2009). "Bitumen – A Smelly but Useful Material of Interest". Archaeology. About.com. Retrieved 23 October 2009.
  14. ^ "Pechelbronn petroleum museum" (in الفرنسية).
  15. ^ "The oil wells of Alsace" (PDF). The New York Times. 23 February 1880. Retrieved 11 February 2012.
  16. ^ أ ب ت خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Dusseault 2001
  17. ^ Dusseault, Maurice (March 2002). Cold Heavy Oil Production with Sand in the Canadian Heavy Oil Industry. Alberta Department of Energy. Archived from the original. You must specify the date the archive was made using the |archivedate= parameter. http://www.energy.alberta.ca/OilSands/1189.asp. Retrieved on 2014-04-22. 
  18. ^ Hein, Fran. "Geology of the Oil Sands" (PDF). Association of Petroleum Engineers and Geoscientists of Alberta. Retrieved 2014-06-04.
  19. ^ O.P. Strausz. "The Chemistry of the Alberta Oil Sand Bitumen" (PDF). جامعة ألبرتا. Retrieved 2014-04-18.
  20. ^ "Canadian Energy Overview 2007". National Energy Board of Canada. May 2007. Retrieved 23 July 2008.
  21. ^ U.S. Department of the Interior, Bureau of Land Management (BLM) (2008). "Tar sands basics". Argonne National Laboratory. Retrieved 14 May 2008. {{cite journal}}: Cite journal requires |journal= (help)
  22. ^ Ancheyta Jorge; Rana Mohan S.; Furimsky Edward (30 November 2005). "Hydroprocessing of heavy petroleum feeds: Tutorial". Catalysis Today. 109 (1–4): 3–15. doi:10.1016/j.cattod.2005.08.025. ISSN 0920-5861.
  23. ^ "Upgrading and Refining" (PDF). Alberta Department of Energy. February 10, 2014. Retrieved 2014-05-05.
  24. ^ أ ب ت ث Howell, David (21 January 2015), Other projects’ layoffs expected to help Sturgeon Refinery, Edmonton, Alberta, http://www.edmontonjournal.com/Other+projects+layoffs+expected+help+Sturgeon+Refinery/10749406/story.html 
  25. ^ أ ب ت Company Profile, 2015, http://www.northwestupgrading.com/company-profile, retrieved on 16 April 2015 
  26. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Alberta_Venture_2013
  27. ^ أ ب ت Morgan, Geoffrey (18 November 2014), The Sturgeon refinery and the high cost of value-added, http://www.albertaoilmagazine.com/2014/11/high-price-adding-value/, retrieved on 16 April 2015 


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للاستزادة

وصلات خارجية