FIELD CASE HISTORY Athabasca Oil Sands Downloaded from http://onepetro.org/JPT/article-pdf/15/05/479/2214045/spe-517-pa.pdf by guest on 29 September 2021 L. A. BELLOWS JUNIOR MEMBER AIME OIL & GAS CONSERVATION BOARD OF ALBERTA V. E. BOHME CALGARY, ALTA. MEMBER AIME Abstract The oil sand is primarily quartz with varying percent­ The location, oil reserves and general geology of ages of silt and clay. Maximum oil saturation is about Alberta's Athabasca oil sands are described with a short 18 per cent by weight in a clean sand but decreases with history of exploration, research and development to date. increasing silt and clay content. Sand with oil saturation Proposed methods of separating the oil from mined sands in excess of about 10 per cent is classed as a "good" grade include hot-water and cold-water separation, and centrif­ while sand containing less than about 5 per cent of oil is ugal and supersonic processes. In situ recovery methods not considered to be economically recoverable by present using combustion, injected fluids or nuclear explosions mining and processing techniques. have been investigated. A project for mining and hot­ . The oil found in the McMurray formation is heavy, water separation is scheduled to begin operation in 1966. VISCOUS and sulfurous. Specific gravity is from 1.002 to Another proposed mining project and an in situ recovery 1.027; viscosity, 3,000 to 400,000 poise at 60F. The sulfur operation are described briefly. The impact of oil-sands content is from 4 to 5 per cent, and the nitrogen content synthetic crude on Alberta's market is discussed. is about 0.4 per cent. The origin of the oil has been explained by a number of different theories but the gen- Introduction The Athabasca oil sands of the McMurray formation' in northeastern Alberta cover an area of about 21,000 sq miles and contain the world's largest reserve of eco­ nomically recoverable oil. Fort McMurray, a small town in the heart of the oil-sands area, is about 235 air miles northeast of Edmonton. A railway serves the town but no year-round roads connect with the rest of Alberta (Fig. 1). The McMurray formation is of early Cretaceous age, deposited unconformably on a limestone surface of Devonian age. The sediments appear to have originated from the Canadian Shield to the east and were deposited in bays and deltas of large fresh-water lakes. The lakes were later replaced by marine seas in which the overlying Clearwater shale was deposited (Fig. 2). The sand body rarely exceeds 200 ft in thickness and is made up of innumerable minor and major lenses of unconsolidated oil-bearing sand interspersed with clay and shale partings of variable thickness, carbonaceous and lignite beds, some rock and boulders. Overburden thins along a topographic trough which contains the Athabasca River and increases in thickness to about 2,000 ft along \ CALGARY the southern and western limits of the oil impregnation. '\ 0 SCALE-MILES Oil sand is exposed on the banks of the Athabasca River ..... 50 o 50 100 150 and its tributaries. 1 ! <I SUBSURfACE EXTENT Of OIL SANDS - _ _ . _ .. _ .._ ... _.~\_. OUTCROP Of OIL SANDS - _ Originai manuscript received in Soeiety of Petroleum Engineers offiee Jan. 14. 1963. Revised manuscript received March 26 1963 Paper -';;"$."4: _... __ .-L ____ ._ .. _... _.. __ _ presented at 92nd Annual Meeting of AIME Feb 24:28 1963 in Dallas, Tex. ' . , , "References given at end of paper. SPE 517 Fig. 1 MAY, 1963 479 small-scale plant to investigate the feasibility of mining the sand and separating the oil by means of a hot-water washing process. At about the same time two private inter­ ests (Abasand and Bitumont) started independent attempts to mine and separate oil sand at locations along the Athabasca River. An attempt was made to recover oil by in situ combustion and steam injection with varying degrees of success, but none of the operations was con­ sidered satisfactory for immediate commercial application. Until the start of World War II all the projects were to obtain road-paving materials-either oil sand in its natural state or separated oil for use in asphalt plants. Fig. 2-Generalized cross-section of the Athabasca oil-sands During the war the Canadian Government became inter­ area (vertical scale exaggerated). ested in the sands as a source of petroleum for gasoline. The Federal Government took over operation of one of erally accepted hypothesis is that the oil migrated from the Abasand plants which was mining some sand and the Devonian limestones. separating oil by a hot-water extraction process. The plant was rebuilt to use a cold-water process but was destroyed Downloaded from http://onepetro.org/JPT/article-pdf/15/05/479/2214045/spe-517-pa.pdf by guest on 29 September 2021 by fire in 1945 before it started operation. Reserves In 1944 the Government of Alberta invested $500,000 The amount of oil in place in the sands is estimated' in the Bitumont enterprise to promote utilization of the to be well over 300 billion bbl, with none appearing to be sands. In 1948 K. A. Clark of the Research Council of recoverable by natural flow. A well which had been drilled Alberta was named to direct the project. A plant was into the oil sands and left open since 1900 was re-entered constructed and operated successfully in 1949, again using in 1957, when about 30 ft of tar-like oil was found to the hot-water extraction method.' have accumulated in the hole. In situ recovery using heat Discovery of major conventional crude oil reserves in in some form or open-pit mining seems to be the most Alberta caused a decrease of interest in oil-sand oil; logical recovery method. however, in 1951 the Government of Alberta sponsored A principal criterion in determining economical recovery an Athabasca Oil Sands Conference. Papers summarizing by mining methods is the ratio of oil sand to overburden. all the oil-sand knowledge" were presented, including Submissions made to the Conservation Board have indi­ papers on the theory of mining by block caving and in cated that a ratio of about 2: 1 or 1: 1 will permit mining situ electrovolatilization. Neither of these theories Was methods to be used for recovery. At an oil sand to over­ considered economic. burden ratio of 2: 1, about 1 \/2 billion bbl of oil is avail­ In 1958 Richfield Oil Corp. proposed the use of a small able; and a ratio of 1: 1 provides an additional 3Yz billion nuclear underground explosion as a source of heat for bbl of oil. These reserve figures are for minable sands recovery of oil from the sand. A special committee studied containing more than 10 per cent oil by weight and would the proposal and in a report submitted in 1959' recom­ be considerably higher if lower quality sands were in­ mended to the Provincial Government that the test be cluded. carried out. However, the international moratorium on By pr:;sen~ly prJPosed mining methods the over-all atomic testing and subsequent Canadian Government poli­ rfcovery of n11rke~able oil is cs:ima:ed to tc about 50 to cies have prevented the experiment. 6J per oent of the oil in place-using 5 per cent oil by weight as a cut-off for the reserve estimates. The only Ownership and Government Legislation in situ recovery estimate available is the 50 to 70 per cent An important section of the history of the oil sands is quoted by Shell for their in situ projecC; and when above­ the historical background of ownership and government ground losses and fuel requirements are included, the legislation concerning the sands. over-all recovery will be in the range of 30 to 45 per cent. In Oct., 1930 all natural resources owned by the Federal Since the major portion of the oil in the sands will likely Government were turned over to the provincial govern­ be recovered by in situ methods, the best current estimate ments. Alberta gained title to virtually all of the oil sands for over-all recovery from this reserve would be in the except for a few parcels reserved by the Federal Govern­ 30 to 45 per cent range. Using a 35 per cent recovery ment and small areas of freehold ownership. The present factor, the oil-in-place estimates will exceed 100 billion policy of the Alberta Government is to retain title to the bbl of marketable oil reserves. sands but to permit exploitation either by issuing prospect­ ing permits which allow exploration of the sands or by History (From Ref. 4) granting 21-year leases permitting the recovery of com­ mercial oil from the sands. An area of about 7,000 sq In 1778 Peter Pond, an explorer of the Canadian north­ miles-covering most of the oil-sands area-was made west, first noted the occurrence of the Athabasca River available for prospecting permits or leases. About 80 oil-sands outcrops in his journals. Surface geological sur­ leases and three permits are currently in force, covering veys were carried out during the 1800's. Some drilling was 2Yz million acres. The royalty payable to the government begun in the early 1900's in search of a "bitumen pool" in the early leases was set at 10 per cent of the value of believed to exist beneath or down dip from the oil sands. the products taken from the sands. Sand was quarried during this period in the vicinity of In 1955 the government enacted legislation exempting McMurray and used in its natural form for road paving.