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Over the past 12 years screening of materials has undergone a dramatic change in both the types and materials used in screen mats and the quality requirements of the finished product. With the main thrust now on quality and a cleaner product a different approach was needed in the operation of sizing screens. New screen mats with many different aperture configurations have been developed using rubber and plastics.to replace the traditional screen mat of woven wire or punched plate.

Jan 1, 1984

By Y. P. Malhotra, JE. C. Carter

"Syncrude's overburden removal requirement ranges from 20 million to 30 million bank cubic metres per year to meet tarsand demands for the production of 129,000 barrels of synthetic crude oil per day. The economic tar-sand lies beneath a variable thickness of overburden materials, composed of silts, clays, some sands of lacustrine origin, wind-deposited sand dunes, and out-wash sands and gravels.For the removal of overburden, Syncrude commissioned its own mobile equipment fleet in January 1981. This fleet consists of two Demag 241 hydraulic shovels, ten Titan 33-15B trucks and support equipment. Prior to this, all overburden removal was being carried out by contractors.This paper presents an overview of overburden removal at Syncrude, with particular reference to the performance of its own fleet.IntroductionThe Syncrude Tar Sands Plant was officially opened on September 15, 1978. After an expenditure of approximately $2.26 billion, the second and the largest commercial tarsands plant was on stream toward a permit production rate of 129,400 barrels of synthetic crude oil per day. The Syncrude Plant, a joint venture of six oil companies, the federal government and the Alberta government, is a major step forward toward the goal of Canadian energy self-sufficiency.The Mildred Lake operation of Syncrude Canada Ltd. Is located 40 km north of Fort McMurray and 480 km northeast of Edmonton in the Province o f Alberta.Synthetic crude oil leaving the plant is a blend of two-third s gas oil and one-third naphtha. The two streams combine in a pipeline and flow to Edmonton. The product takes six days to make the journey, arriving at four locations in the city Imperial's Strathcona Refinery, Gulf's Edmonton Refinery, the Interprovincial pipeline terminal and the Trans-Mountain pipeline terminal. Each Syncrude owner receives a share of oil equal; to its percentage of ownership in the project. At the present time, the oil is being utilized by Canadian refineries from Vancouver to Montreal."

Jan 1, 1983

By J. M. Mutmansky, R. A. Jankowski, M. A. K. Mohamed

"SYNOPSISKnown health hazards associated with the breathing of respirable dusts, particularly silica dust, during mining are becoming a great concern in many parts of the world. The search for effective and low cost dust control methods for underdeveloped countries will help in improving the productivity and keeping the mine environment safe. This article addresses the problem by providing suggestions concerning the easiest and most cost effective methods to control respirable dust in mining and mineral processing operations. INTRODUCTIONMedical BackgroundLung diseases caused by dust in mining operations have been recognized by mankind since the time of the Roman Empire. The writings of Pliny the Younger on natural history reported on maladies associated with dust in mining in the first century AD. However, no significant advances in controlling the lung diseases of miners came about for many centuries. The effects of mineral dusts were further described by Georgius Agricola in his sixteenth century book on mining (Agricola, 1556). After the appearance of Agricola""s book, lung diseases were more readily recognized, but the nature and severity of the ailments associated with mineral dusts could not be readily interpreted.In 1896, the discovery of x-rays by Roentgen advanced the diagnosis of lung diseases and the knowledge of what causes these diseases. In addition, the discovery allowed medical personnel some method of judging the extent and severity of the lung diseases in human beings. During the ensuing years, the term 'pneumoconiosis' became the common term to describe any of the diseases of the lung in which dust particles deposited in the lungs caused fibrous tissue and loss of some of the respiratory function. However, little in the way of social remedies for the diseases resulted until much later. Society was still not ready to act decisively to reduce the causes of lung disease due to the dusty conditions in the work place.Social action against lung diseases did not occur in the United States (US) until the 1930s. At that time, a tunnel driven through a sandstone mountain near Gauley Bridge. West Virginia, caused the death of several hundred workers due to acute silicosis, a severe form of pneumoconiosis caused by silica (Seaton, 1975). Dust conditions in this tunnel were quite bad, causing many of the workers to be subjected to extremely high silica dust concentrations. The severity of the disease in many of the workers became known to the public and prompted the US Congress and many of the states to enact laws to reduce the dust levels."

Jan 1, 1998

By Marcela Morvová, Mário Janda, Morva Imrich

"The possibilities of greenhouse gas mitigation using various methods are brought out. The special case of utilization of mixture of CO2 with other greenhouse gases in a synergetic way inside non-thermal plasma based system is described in detail.Measurements on pilot system comprising pyrolysis chamber as alternative energy system (production of hydrogen and liquid tar) were made for various biomass and waste as the input material. The exhaust from this system was treated with non-thermal plasma gap suitable for up to 650Nm3/hour of exhaust gas flow. Condensable portion of exhaust is liquefied in distillation unit; produced hydrogen is stored on-line inside nano sized carbon of our own production.The CO2 removal efficiency varies depending on exhaust composition between 45 to 98%. Other oxides as CO, NOx, SOx and several hydrocarbons and VOC are also removed. The main product connected with CO2 removal is a solid powder of proteinoid nature. There exist strong probability, that precursor of the origin of life on the Earth from primary atmosphere were formed in the similar way as it is present in the electric discharge system used. Our system is equipped with on-line as well as ex-post analysis of all forms of products. We have also developed a system for recuperation of all forms of produced heat. It is stored inside as latent heat of waxes.IntroductionNatural greenhouse effect on the Earth is caused mainly by water vapour with the average absolute concentration about 4%. Other gases able to absorb long-wave radiation and thus this causing greenhouse effect are CO2, CH4, N2O, halocarbons and as precursors ozone and NOX. Some of them we produce and introduce into atmosphere in large quantities during production of energy and in transport. This factor leads to permanent increase of average temperature of air, sea and oceans, so called global warming.Nowadays large amount of data exists showing that the temperature of Earth in the last 150 years has been continually increasing. It represents about 03°C per ten years and the most of climatologist believe, that the increased concentration of greenhouse gases in the atmosphere is responsible for this effect.The most important greenhouse gas is carbon dioxide CO2. Majority of CO2 emissions comes from electric power stations working with fossil fuels, cars and industry. Burning of fossil fuels contribute up to 80% to world wide anthropogenetic emissions of CO2."

Jan 1, 2010

By R. Pressacco

"IntroductionAgrium’s history in fertilizer production and marketing goes back to 1931. Today, Agrium Inc. is a world leader in the production, distribution, and marketing of fertilizers and related products to the agricultural industry. Agrium is the largest North American producer of nitrogen fertilizers, a major producer of phosphate and potash fertilizers, and a world leader in fertilizer wholesale distribution and retail marketing. The mine at Kapuskasing is located some 40 km southwest of Kapuskasing, Ontario (Fig. 1). It has been developed to supply high-quality, low-cost phosphate rock to the company’s Redwater, Alberta facility, where it is an ingredient in ammonium phosphate fertilizer production. The Kapuskasing mine is the only phosphate mine in Canada and will rank as one of the highest-grade phosphate mines in the world (Clark and Duncan, 1999). Apatite is the principal ore mineral mined at the Kapuskasing Phosphate Operations.GeologyThe first record of exploration in the area was from a program executed by Continental Copper Mines in 1955 which evaluated the magnetic anomaly located in the Cargill and Cumming townships for its base metal potential. Intermittent exploration of the base metal potential of this magnetic anomaly continued in the following years, until the phosphate potential of the area was first examined in 1974 by International Minerals Corporation which recognized the presence of a layer of apatite sands overlying the carbonatite host rocks.The local geology consists of a core complex of multi-phased carbonatite rocks which are surrounded by a ring of pyroxenite, and have provided a U-Pb age date of 1907 Ma ± 4 (Sage, 1988). These two rock types are in turn situated within quartz diorite gneisses that form a large portion of the Kapuskasing Structural Zone (Fig. 2). The carbonatite host rock is sub-divided into two sub-types: sovite and rauhaugite. The sovite is a medium- to coarse-grained, white, banded rock in which calcite is the dominant carbonate species and it includes accessory minerals such as phlogopite, magnetite, clinohumite, apatite, olivine, pyrrhotite, and amphibole. Apatite can reach 15% abundance in this rock type (Sage, 1988). In sharp contrast to the sovite, the rauhaugite appears as a massive, fine-grained, dense, beige to tan-coloured rock in which dolomite is the dominant carbonate species. Phosphate values can range to 14% P2O5 in the rauhaugite."

Jan 1, 2001

By Choon K. Quan

Subsidence is a surface manifestation of the underground development and exploitation of minerals, and its impact on the environment is becoming of increased concern, particularly in the face of an accelerating demand for energy and minerals. In the United States, the state-of-the-art in subsidence prediction, control, and prevention and in subsidence-related damage abatement has not progressed to the level achieved in other countries. To bridge this gap, the Bureau of Mines, through its Mining Environmental Research program, is pursuing a comprehensive subsidence investigation, specifically designed to address major problems on the local, regional, and national level.

Jan 1, 1979

By Alphonce Wikedzi, Mussa D. Budeba, Samwel V. Manyele, Sospeter P. Maganga

The present study provides an overview of the challenges and opportunities in processing complex gold-copper ores. The systematic literature review was conducted using Scopus database and seven-step methodological approach. The study indicates that the major challenges in processing complex gold-copper ores through the conventional cyanidation method include (1) increase in cyanide consumption; (2) increase in cyanide destruction cost; (3) low gold recovery; (4) decrease in adsorption efficiency; (5) decrease in electrowinning efficiency, and (6) difficulties in the measurement of free cyanide concentration in the leaching system. Moreover, the study indicates that several methods have been developed and some have been implemented in the mining industry for processing complex gold-copper ores. This includes ore segregation, pre-aeration, pre-treatment methods (e.g., ammonia), alternative lixiviants (e.g., thiosulfate, thiocyanate, glycine), cyanide destruction methods, and cyanide and copper recovery technologies. The study concluded that using lixiviant mixtures (e.g., cyanide-glycine), pre-treatment with environmentally friendly reagents (e.g., glycine) and the integrated membrane-based process (SuCy process) are new directions in processing complex gold-copper ores. However, more investigations are required to advance these processes to a commercial scale.

Sep 30, 2023

By Don Phelps, Christopher Tattersall, David McAllister

Located south of downtown Seattle, the Beacon Hill Station & Tunnels is the key section of the southern segment of Sound Transit’s proposed new LINK light rail system. This paper presents an overview of the design, which includes 4,300 ft of segmentally-lined bore twin tunnels and a deep mined station. With platforms located156 feet below grade, the station itself is only the second large-scale mined station in soil the US. Its complex geometry combined with variable soil conditions—sands, silt sand clays with slickensides—challenged the designer’s to come up with a SEM-based design that addresses the owner’s risk, cost and schedule concerns.

Jan 1, 2003

By C. Cutts, K. Wheatley

The Dragon Lake Zone (uranium prospect) comprises a N160º trending vein that is approximately 110 m long, up to 5 m wide and from 1 to 40 m high. The zone is mostly within altered sandstone of the Fair Point Formation, the basal unit of the Paleoproterozoic Athabasca Group, but it also extends downward (up to 3.5 m) into basement rocks that occupy the northerly trending Maybelle River Shear Zone (MRSZ). This subvertical shear zone separates graphitic paragneiss and weakly deformed granitoid rocks to the east from non-graphitic paragneiss and foliated granitoid rocks to the west. The Dragon Lake Zone cuts across both the MRSZ and N060º-N070º-trending cross-faults that offset the shear zone but not the mineralized vein, which contains values up to 54.5% U over 50 cm core length. Strong chloritization occurs in graphitic paragneiss and sandstone adjacent to mineralization. Silica was depleted from the basement rocks and redeposited at the borders of the 5-15-m-wide alteration zone, as well as within overlying sandstone of the Manitou Falls Formation. There are minimal alteration effects in the overlying Lazenby Lake Formation. Geochemistry shows that the alteration zone in the Fair Point Formation is highly anomalous in metals, most notably in Ni, As, U, Pb, Co, and B. Clay within this zone is illitic and Fe-rich chlorite is also present. Brittle deformation is not as widespread or as well developed in the Fair Point Formation as it is in the overlying Manitou Falls Formation, which is extensively brecciated and contains some anomalous metal values.

Jan 1, 2013

By G. Barrasso

REACH was proposed by the EU Commission in October 2003 and stands for the Registration Evaluation, Authorisation and Restriction of Chemicals. It requires that all substances identified as persistent, bio-accumulative and toxic, whether the risk of those chemicals being released is real or perceived, require registration prior to them being allowed to be imported into the European Union. An internal investigation by the metals industry indicates that almost all primary raw materials streams would be classified as hazardous due to the potential health or environmental hazard properties of one or more of their ingredients. REACH uses a wide definition for chemicals and metals and as such its implications greatly impact the entire supply chain of the metals industry. The process of registration would require the producer/ importer to produce a dossier. Initiatives along the same lines as the EU REACH are also coming up in other parts of the world. REACH requires registration of at least four substances manufactured by the aluminium industry: aluminium metal, including powder, aluminium oxide, and aluminium hydroxide. The proposed legislation permits the affected companies to band together to form a consortium to develop certain aspects of the registration application. The aluminium industry has established a consortium and testing is currently underway.

Jan 1, 2006

By M Akhtar, E Jak, M Shevchenko

This article presents an overview of the experimental phase equilibria studies of S-containing systems (Ni-Sn-S, Cu-Sb-S, and Cu-Sn-S) and As-containing systems (Fe-Sb-As and Fe-Sn-As). These systems improve the prediction capabilities of FactSage in a 20-component ‘Cu2O’-PbO-ZnOFeO- Fe2O3-CaO-SiO2-S-(Al2O3-MgO-CrO-Cr2O3-Na2O)-(As, Sn, Sb, Bi, Ag, Au, Ni, Co) system for complex pyrometallurgical operations during both refining and recycling. Experiments involved equilibration at predetermined temperatures (300–1200°C) with or without preheating, followed by rapid quenching in a brine. Quenched samples were then directly measured using an electron probe microanalyser. For the Ni-Sn-S system, liquid phases (NiS- and SnS-rich mattes and liquid metal) and solid phases (Ni1+xSn, SnS, Ni3Sn, FCC-Ni, Ni1-xS, NiS2, Ni3Sn4, SnS2, Sn2S3 and β-Ni3S2) were observed. A new Ni3Sn2S2 phase was found to melt incongruently. For the Cu-Sb-S system, liquid metal, matte, FCC-Cu, digenite, Sb, CuSbS2, Cu3SbS3 and Cu3SbS4 phases were observed. For the Cu-Sn-S system, liquid metal, matte, digenite, SnS and Cu3Sn phases were found at liquidus.

Jun 17, 2024

By John L. Walkinshaw

It is obviously not possible in the time given me today to review in great detail all the research of the past 20 years that the (FHWA) has sponsored or participated in. In this presentation I will highlight some of the principal programs that I am familiar with. This handout lists practically all the reports prepared for the FHWA involving deep foundations and some related work involving the same structural elements (piles, shafts, ground anchors).

Jan 1, 1993

By Marc Symbaluk

Core Programs Current ? Aboriginal Involvement Program ? Adaptive Forest Management / Forest History Program ? Grizzly Bear Research Program ? Natural Disturbance Program ? Foothills Growth and Yield Association ? Foothills Stream Crossing Program ? Fish and Watershed Program ? Caribou Landscape Management Association ? Social Science Program ? Local Level Indicators Program ? Communications and Extension Program ? Geographic Information Systems Program ? Mountain Pine Beetle Ecology Program In Development ? Climate Change Program ? Forest Community Program ? Water, Quantity and Quality Program (Water for Life) ? Circumboreal Initiative ? Yellowhead Ecosystem Management Group

May 1, 2008

By Ray E. Harris

Introduction A resource of more than 122 Gt (134 billion st) of minable trona and mixed trona and halite underlies an area of about 3400 km2 (1300 sq miles) west of Green River, WY (Culbertson, in preparation) (Fig. 1). In 1982, the total domestic consumption of soda ash (refined trona) was 6 Mt (6.7 million st) (Kostick, 1983). About 90% of this came from Wyoming trona. This enormous deposit occurs in the Wilkins Peak Member of the Green River Formation that is of Eocene age. This formation is derived from sediments deposited in a large lake named Gosiute. Lake Gosiute occupied the Green River Basin in southwestern Wyoming some 38 to 54 million years ago. The Wilkins Peak Member represents a restricted, evaporite-rich cycle of deposition when the trona deposits were formed. A total of 42 trona beds are known. Of these, 25 are of sufficient thickness and extent to be considered minable (Culbertson, in preparation). The production of sodium compounds from the trona deposits in the Wilkins Peak Member began in 1896 when wells were drilled within the present boundaries of the town of Green River. The purpose of the drilling was for extraction of sodium carbonate brines. Sodium carbonate (sal soda) was removed from these brines at a plant in Green River. Bedded trona was discovered in 1938 in a core from an oil well drilled south of Westvaco. In 1947, the underground mining of trona began. Production has continued from 1948 to date. Currently, five companies are mining trona and producing soda ash from the Wilkins Peak Member in Wyoming. Additionally, Allied Chemical Co. mines and processes trona for Church and Dwight's sodium bicarbonate (baking soda) operation in Green River. Competition in the soda ash industry depends primarily on the efficiency of mining and refining, allowing for lower-cost production. Newer plants and mine designs should increase efficiency. Solution mining holds promise as an even lower-cost method of mining. Employment in the soda ash industry is declining since the newer mining and refining methods are less labor intensive. Declines in employment, however, may be offset as production increases. Due to the large resource, the availability of minable trona should not be a problem for perhaps hundreds of years. Geology of Wyoming trona deposits Forty-two beds of trona or mixed trona and halite occur in the

Jan 10, 1985

By Jean Rosaire

?GWIOP Location ?Climate and Physiography ?History ?Geology ?Deposit Types ?Mineralization ?Historical Mineral Resources ?Conclusions and Work Program

May 1, 2007

By Christina Dahnér, Kristina Jonsson, Savka Dineva

The iron-ore underground Kiirunavaara mine (Sweden) has been seismically active since 2008. In 2021 the production is on levels 1079 and 1108 m, at the deepest. The seismic activity has changed in character over time with one step change in 2015 when the number of large (ML>2) seismic events increased, and another one when the mine experienced a seismic event with Mw 4.2 in 2020. In 2017, the mine evaluated Hydraulic Fracturing (HF) as a possible mitigation technique for larger seismic events and a one-hole trial was performed. The trial proved promising, and it was decided to go forward with a large-scale trial covering an entire production area in the mine. The large-scale trial consists of 25 fracturing holes, 50 – 100 m long, running along 500 m out of the ~4500 m long orebody and spanning between production levels 1108 m and 1252 m. The fracturing process continued for a year, resulting in ~38,000 seismic events with −3.3<ML<1.4. The breakdown pressure varied between fractures in the same hole as well as between holes in the same area. Average breakdown pressure per hole was between 12 MPa and 50 MPa. The seismic response to HF in 2021 varied greatly from hole to hole and between fractures in the same hole. The variation in response could be related to the geological conditions and the infrastructure, such as large caving ore passes. In this paper some details about the experiments and broad preliminary analysis of the effect of the HF by using seismic source parameters of the induced seismic events are presented: 1) Distribution of seismic activity, 2) the ‘equivalent’ magnitudes for each hole calculated from the cumulative seismic energy and seismic potency released during the fracturing, compared with the local geological conditions; 3) the predominant failure mechanism of the seismic events caused by HF was defined. A difference in the behaviour between larger and smaller events was noticed, as ML>0 events seem to be compression type failures and ML<0 events seem to be related to slip on pre-existing structures. No seismic events related to creation of a new fracture have been identified yet.

Apr 26, 2022

By Peter L. McSwiggen

The mineralogy of the Biwabik Iron Formation changes dramatically from west to east as the formation nears the basal contact of the Duluth Complex. This reflects a contact metamorphism that took place with the emplacement of the igneous Duluth Complex at tem¬peratures as high as 1200 °C. However, the mineralogy of the Biwabik Iron Formation also varies vertically through the stratigraphy of the unit. This variability in both the vertical and horizontal dimensions makes it difficult to predict exact horizons where specific minerals will occur. The iron-formation has been subdivided into four broad stratigraphic units (lower cherty, lower slaty, upper cherty, and upper slaty) and into four lateral mineralogical zones (1-4). Zone 1, the westernmost zone, is characterized by quartz, magnetite, hematite, carbonates, talc, chamosite, greenalite, minnesotaite, and stilpnomelane. The silicate mineralogy in Zone 2 of the Biwabik Iron Forma¬tion changes very little. However, the minerals begin to change dramatically in Zone 3. Most significantly, Zone 3 is characterized by the appearance of grunerite in both a tabular form and a fibrous form. In Zone 4, the original silicate minerals have completely reacted, and a new suite of minerals occupies the iron-formation. These include grunerite, hornblende, hedenbergite, ferrohypersthene (ferrosilite), and fayalite.

Jan 1, 2007

By Peter L. McSwiggen

The mineralogy of the Biwabik Iron Formation changes dramatically from west to east as the formation nears the basal contact of the Duluth Complex. This reflects a contact metamorphism that took place with the emplacement of the igneous Duluth Complex at temperatures as high as 1200 °C. However, the mineralogy of the Biwabik Iron Formation also varies vertically through the stratigraphy of the unit. This variability in both the vertical and horizontal dimensions makes it difficult to predict exact horizons where specific minerals will occur. The iron-formation has been subdivided into four broad stratigraphic units (lower cherty, lower slaty, upper cherty, and upper slaty) and into four lateral mineralogical zones (1-4). Zone 1, the westernmost zone, is characterized by quartz, magnetite, hematite, carbonates, talc, chamosite, greenalite, minnesotaite, and stilpnomelane. The silicate mineralogy in Zone 2 of the Biwabik Iron Formation changes very little. However, the minerals begin to change dramatically in Zone 3. Most significantly, Zone 3 is characterized by the appearance of grunerite in both a tabular form and a fibrous form. In Zone 4, the original silicate minerals have completely reacted, and a new suite of minerals occupies the iron-formation. These include grunerite, hornblende, hedenbergite, ferrohypersthene (ferrosilite), and fayalite. © 2007 Elsevier Inc. All rights reserved. Keywords: Biwabik Iron Formation; Duluth Complex; Mineralogy

Jan 1, 2007

By R G. Barker

This paper reviews the annual status of the New Zealand mining industry (metallic minerals and coal) including key aspects such as mineral production, mineral exploration expenditure, commodity price trends, key industry players, market activity and other significant commercial factors. &nbsp; Strong commodity prices during 2006 have been underpinned by a number of key factors including US dollar weakness and emerging market demand, particularly from countries such as China and India. In real terms commodity prices have recovered significantly since 2002 and are currently at 20-year highs. &nbsp; New Zealand exploration spending on metallic minerals (predominantly gold) is at a 15 year high driven by rising global commodity prices. New Zealand gold production in 2006 was about 340,000 oz and is expected to grow in 2007 as new mines at Frasers and Globe-Progress (Oceania Gold) and Favona (Newmont) come on stream. Gold production broadly lags 10 years behind exploration spending and exploration activity over the last five years remains well below that seen in the early 1980Æs. Expenditure on coal exploration shows a similar trend with strong growth from a low base over the last five years, reaching over $11 M in 2006. Total coal production in 2006 was 5.9 Mt, an increase of 10% on 2005 with imports from Indonesia adding a further $1.1 Mt. &nbsp; Newmont and Oceana Gold are by far the largest public gold mining companies operating in New Zealand, although only Oceana Gold maintains a presence on the local stock exchange. Other metals explorers with New Zealand projects include a range of public-listed Juniors (market capitalisation less than NZ$50m) domiciled largely in New Zealand, Australia and/or Canada. Capital-raising on public markets directed towards New Zealand exploration is estimated at around NZ$12 M for 2006, the bulk of this coming via Glass EarthÆs NZ$10 M IPO on the NZAX in October. &nbsp; The New Zealand Coal sector is dominated by the state-owned enterprise Solid Energy with around 80% market share by production. Other domestic coal competition remains limited, and includes the L&amp;M Group, Pike River Coal, Eastern Corporation, and New Vale (acquired by Solid Energy in 2007). Pricing parity comes mainly from imported coal and global thermal coal prices have remained strong during 2006 at around US$45-55/t, driven by continued expansion in Chinese demand. Coking coal prices have eased 16% since 2005 to around US$98/t in 2007. &nbsp; Although recent increases in exploration spending suggest a renaissance in the New Zealand minerals sector, long-run trends indicate that we have simply rebounded from a low base over the last five years and much work is still to be done to stimulate further growth in the mining industry to maintain minerals production at current levels. Key industry challenges include marketing exploration opportunities to local and overseas investors, building a critical mass of NZX-listed explorers and providing an internationally competitive environment to attract further capital and expertise.

Jan 1, 2007

By Kristine Haug

Although most in situ operations in Alberta do not encounter significant problems during resource extraction, there have been a few documented occurrences of oil or steam releases as a result of compromised caprock seals. The objective of the Oil Sands Caprock Integrity Project (OSCRIP) is to characterize the units above and below bitumen zones to determine which geological factors affect the quality of the caprock seal. In addition, geomechanical properties and stress measurements of the bitumen reservoir and overlying units will be examined to provide a better picture of the containment conditions in which in situ operations occur. The information from this study will aid regulatory staff and industry in determining the zone-specific geological and geomechanical factors that could affect the design, operation, and feasibility of in situ recovery projects. The OSCRIP study area (Townships 87 to 99 and Ranges 1 to 13, West 4th Meridian) encompasses the surface mineable area, the northeast extent of the Wabiskaw-McMurray bitumen deposit and the Clearwater Formation, as well as a wide band of the Devonian salt-dissolution zone. Regional geological mapping of the Cretaceous strata focuses on the spatial extent and thickness of the caprock seal. Mapping of the underlying Devonian strata is targeted at better understanding the potential effects of salt dissolution and collapse of overlying strata on the integrity of the caprock seal. Examination of LiDAR (Light Detection And Ranging) bare earth DEM in the study area has revealed localized depressions that may represent sinkholes rooted in subsurface collapse features in Devonian carbonate and evaporite strata. Mapping the location and understanding the timing of salt dissolution-related features and deformation in the Devonian strata will help address questions about the possible effect that geological structures, such as sinkholes, have on the integrity of the caprock, as well as the potential for localized variations in the stress regime of the bitumen zone and overlying units. The stress regime in units above 350 m is such that any induced fractures are believed to be horizontal, and therefore, there would appear to be no mechanisms that would allow these fractures to reach the surface. However, recent incidents have shown that vertical pathways can occur, linking the subsurface to the surface. The final phase of the project will evaluate the changes that may occur in the stress regime under thermal operating conditions in the study area.

Jun 1, 2012