71.J.Yerushalmi,Proceedings of the 1992Eastern Oil Shale Symposium ,IMMR Press,
Lexington,Ky.,1993,p.367.
72.C.Du,Proceedings of the 18th Oil Shale Symposium ,Colorado School of Mines
Press,Golden,Colo.,1985,210–215.
73.B. C.Wright,Alternate Energy ’89Proceedings ,Council on Alternate Fuels,
Washington,D.C.,1989,175–194.
E DWIN M.P IPER
Piper Designs LLC R OBERT N.H EISTAND Consultant
TAR SANDS
In addition to conventional petroleum (qv)and heavy crude oil,there remains another subclass of petroleum,one that offers to provide some relief to poten-tial shortfalls in the future supply of liquid fuels and other products.This subclass is the bitumen found in tar sand deposits (1,2).Tar sands,also known as oil sands and bituminous sands,are sand deposits impregnated with dense,viscous petroleum.Tar sands are found throughout the world,often in the same geographical areas as conventional petroleum.
Petroleum,and the equivalent term crude oil,cover a vast assortment of materials consisting of gaseous,liquid,and solid hydrocarbon-type chemical com-pounds that occur in sedimentary deposits throughout the world (3).When pet-roleum occurs in a reservoir that allows the crude material to be recovered by pumping operations as a free-?owing dark-to light-colored liquid,it is often referred to as conventional petroleum.
Heavy oil is another type of petroleum,different from conventional petro-leum insofar as the ?ow properties are reduced.A heavy oil is much more dif ?-cult to recover from the subsurface reservoir.These materials have a high viscosity and low API gravity relative to the viscosity and API gravity of conven-tional petroleum (Fig.1)(3,4),and recovery of heavy oil usually requires thermal stimulation of the reservoir.
The de ?nition of heavy oil is usually based on API gravity or viscosity,but the de ?nition is quite arbitrary.Although there have been attempts to rationa-lize the de ?nition based on viscosity,API gravity,and density (2,3),such de ?ni-tions,based on physical properties,are inadequate,and a more precise de ?nition would involve some reference to the recovery method.
In a general sense,however,the term heavy oil is often applied to a petro-leum that has a gravity <208API.The term heavy oil has also been arbitrarily used to describe both the heavy oil that requires thermal stimulation for recovery from the reservoir and the bitumen in bituminous sand (also known as tar sand or oil sand)formations,from which the heavy bituminous material is recovered
Kirk-Othmer Encyclopedia of Chemical Technology .Copyright John Wiley &Sons,Inc.All rights reserved.10.1002/0471238961.20011819160509.a01
222TAR SANDS Vol.
1
by a mining operation.Extra heavy oil is the subcategory of petroleum that occurs in the near-solid state and is incapable of free ?ow under ambient conditions.The bitumen from tar sand deposits is often classi ?ed as an extra heavy oil.
Tar sand,also variously called oil sand (in Canada)or bituminous sand,is the term commonly used to describe a sandstone reservoir that is impregnated with a heavy,viscous black extra heavy crude oil,referred to as bitumen (or,incorrectly,as native asphalt).Tar sand is a mixture of sand,water,and bitu-men,but many of the tar sand deposits in the United States lack the water layer that is believed to cover the Athabasca sand in Alberta,Canada,thereby facilitating the hot-water recovery process from the latter deposit.The heavy asphaltic organic material has a high viscosity under reservoir conditions and cannot be retrieved through a well by conventional production techniques.
It is incorrect to refer to bitumen as tar or pitch.Although the word tar is somewhat descriptive of the black bituminous material,it is best to avoid its use in referring to natural materials.More correctly,the name tar is usually applied to the heavy product remaining after the destructive distillation of coal or other organic matter.Pitch is the distillation residue of the various types of tar.
Physical methods of fractionation of tar sand bitumen usually indicate high proportions of nonvolatile asphaltenes and resins,even in amounts up to 50%wt/wt (or higher)of the bitumen.In addition,the presence of
ash-forming
102
103
104106
105
1
10
V i s c o s i t y , c p s
Temperature, °C
Fig.1.Relative viscosity data for conventional petroleum,heavy oil,and bitumen.
Vol.1
TAR SANDS 223
224TAR SANDS Vol.1 metallic constituents,including such organometallic compounds as those of vanadium and nickel,is also a distinguishing feature of bitumen.
Asphalt is prepared from petroleum and often resembles bitumen.When asphalt is produced simply by distillation of an asphaltic crude,the product can be referred to as residual asphalt or straight-run petroleum asphalt.If the asphalt is prepared by solvent extraction of residua or by light hydrocarbon(pro-pane)precipitation,or if blown or otherwise treated,the term should be modi?ed accordingly to qualify the product,eg,propane asphalt.
1.Origin of Bitumen
There are several general theories regarding the origin of the bitumen.One the-ory is that the oil was formed locally and has neither migrated a great distance nor been subjected to large overburden pressures.Because under these condi-tions the oil cannot have been subjected to any thermal effects with the resulting decomposition or molecular changes,it is geologically young and therefore dense and viscous.
Another theory promotes the concept of a remote origin for the bitumen,or, more likely,the bitumen precursor,both geographically and in geological time. The bitumen precursor,originally resembling a conventional crude oil,is assumed to have migrated into the sand deposit,which may originally have been?lled with water.After the oil migrated,the overburden pressures were relieved,and the light portions of the crude evaporated,leaving behind a dense,viscous residue.
Included in the remote origin theory is the postulate that the light hydro-carbons were destroyed by bacteria carried into the petroleum reservoirs in oxy-genated,meteoric waters.The remote origin theory would explain the water layer surrounding sand grains in the Athabasca deposit.However,because the metals and porphyrin contents of bitumen are similar to those of some conven-tional Alberta crude oils of Lower Cretaceous age and because Athabasca bitu-men has a relatively low coking temperature,the bitumen may be of Lower Cretaceous age.This is the age of the McMurray formation(Canada),which is geologically young.This evidence supports the theory that the oil was formed in situ and is a precursor,rather than a residue of some other oil.The issue remains unresolved as of this writing(ca1997).
2.Occurrence
Many of the reserves of bitumen in tar sand formations are available only with some dif?culty,and optional re?nery methods are necessary for future conver-sion of these materials to liquid products,because of the substantial differences in character between conventional petroleum and bitumen(Table1).
Because of the diversity of available information and the continuing attempts to delineate the various world oil sands deposits,it is virtually impos-sible to re?ect the extent of the reserves in terms of barrel units with a great degree of accuracy.The potential reserves of hydrocarbon liquids that occur
Vol.1TAR SANDS225
in tar sand deposits have,however,variously been estimated on a world basis to be in excess of477?109m3e3?1012bblT.Reserves that have been estimated for the United States are believed to be in excess of795?104m3e50?106bblT, although estimates vary.Bitumen reserves throughout the world can compare favorably with reserves of conventional crude oil.
Tar sand deposits are widely distributed throughout the world(Fig.2) (5,6)and the various deposits have been described as belonging to two types: stratigraphic traps and structural traps(Table2;Fig.3)(7).However,there are the inevitable gradations and combinations of these two types of deposits, and thus a broad pattern of deposit entrapment is believed to exist.In general terms,the entrapment character of the very large tar sand deposits involves a combination of both stratigraphic and structural traps.
The largest tar sand deposits are in Alberta,Canada,and in Venezuela. Smaller tar sand deposits occur in the United States(mainly in Utah),Peru, Trinidad,Madagascar,the former Soviet Union,Balkan states,and the Philip-pines.Tar sand deposits in northwestern China(Xinjiang Autonomous Region) also are large;at some locations,the bitumen appears on the land surface around
Karamay,China.The largest deposits are in the Athabasca area in the province of Alberta,Canada,and in the Orinoco region of east central Venezuela.
The Athabasca deposit,along with the neighboring Wabasca,Peace River,and Cold Lake heavy oil deposits,have together been estimated to contain 1:86?1011m 3e>1:17?1012bbl Tof bitumen.The Venezuelan deposits may at least contain >1:60?1011m 3e1:0?1012bbl Tbitumen (2).Deposits of tar sand,each containing >3?106m 3e20?106bbl Tof bitumen,have also been located in the United States,Albania,Italy,Madagascar,Peru,Romania,Trinidad,Zaire,and the former Soviet Union,comprising a total of ca 450?109m 3e2:8?1012bbl T.
Fig.2.Principal tar sand deposits of the world,where .represents >2;385;000m 3<15?106bbl Tbitumen;N,probably >159;000m 3e<1?106bbl Tbitumen;and H,reported occurrence information limited.
Table 2.Tar Sand Deposits and Mode of Entrapment a Number Deposit
Location
1.stratigraphic trap:structure of little importance;short-distance migration assumed
Sunnyside,P.R.Springs,Santa Cruz 2.structural/stratigraphic trap:
folding/faulting and unconformity equally important
O ?cina –Temblador tar,Bemolanga,Asphalt Ridge,Melville Island,Guanoco,Kentucky deposits 3.structural trap:structure important;long-distance migration assumed;unconformity may be absent Whiterocks,La Brea 4.intermediate between 1and 2Athabasca,Edna,Sisquoc,Santa Rosa 5.
intermediate between 2and 3
Selenizza,Derna
a
See Fig.3.
226TAR SANDS Vol.1
Vol.1TAR SANDS227
Fig.3.Types of traps for tar sand deposits,where represents a stratigraphic trap,?, an intermediate between stratigraphic and structural/stratigraphic traps;?,a structural/ stratigraphic trap;.,an intermediate between structural/stratigraphic and structural traps;and4,a structural trap.
The Alberta(Athabasca)tar sand deposits are located in the northeast part of that Canadian province(Fig.4).These are the only mineable tar sand deposits undergoing large-scale commercial exploitation as of this writing(ca1997).
The Athabasca deposits have been known since the early1800s.The?rst scienti?c interest in tar sands was taken by the Canadian government in 1890,and in1897–1898,the sands were?rst drilled at Pelican Rapids on the Athabasca River.Up until1960,many small-scale commercial enterprises were attempted but not sustained.Between1957and1967,three extensive pilot-plant operations were conducted in the Athabasca region,each leading to a proposal for a commercial venture,eg,Suncor and Syncrude.
The Venezuelan tar sands are located in a50–100-km belt extending east to west for>700km,immediately north of the Orinoco River.The precise limits of the deposit are not well de?ned because exploration efforts in the past concen-trated on light and medium crude accumulations.
The geological setting of the Orinoco deposit is complex,having evolved through three cycles of sedimentation.The oil is contained by both structural and stratigraphic traps,depending on location,age of sediment,and degree of faulting.The tar sands are located along the southern?anks of the eastern Vene-zuelan basin,where three distinct zones are apparent from north to south:a zone of tertiary sedimentation,a central platform with transgressive overlapping sediments,and a zone of erosional remnants covered by sediments.The deposit also contains three systems of faulting.All the faults are normal and many are concurrent with deposition.
Tar sands in the United States are contained in a variety of separate deposits in various states(Fig.5)but because many of these deposits are
small,information on most is limited (8).Attempts at development of the depos-its have occurred primarily in Utah.
3.Properties
Tar sand has been de ?ned as sand saturated with a highly viscous crude hydro-carbon material not recoverable in its natural state through a well by ordinary
production methods (2–8).Technically the material should perhaps be called bituminous sand rather than tar sand because the hydrocarbon is bitumen,ie,a carbon disul ?de-soluble oil.
The data available are generally for the Athabasca materials,although workers at the University of Utah (Salt Lake City)have carried out an intensive program to determine the processibility of Utah bitumen and considerable data have become available.Bulk properties of samples from several locations (Table 3)(9)show that there is a wide range of properties.Substantial differences exist between the tar sands in Canada and those in the United
°
49°Fig.4.Tar sand and heavy oil deposits in Alberta,Canada.
228TAR SANDS
Vol.1
States;a difference often cited is that the former is water-wet and the latter, oil-wet(10).
Canada United States
sand is water-wet,thus disengagement of bitumen is ef?cient using hot-water process(caustic?sodium hydroxide; bitumen recovery>98%)sand is oil-wet,thus ef?cient dis-
engagement of bitumen requires
high shear rates(caustic?sodium
carbonate;bitumen recovery$95%)
formations usually unconsolidated formations usually consolidated
to semiconsolidated by mineral
cementation
few deposits have been identi?ed
(Alberta contains ca0.4m3bitumen)numerous deposits identi?ed(33major deposits?12m3bitumen;20minor
deposits?12m3bitu-men);
total resource?6.5m3bitumen
(2.6m3measured and3.8m3
billion speculative)
problems exist in settling and removal of clay from tar sand deposits and
process streams little is known about the nature and effect on processing of clays
bitumen properties fairly uniform (sulfur?4:5à5:5wt%,
nitrogen?0.1–0.5wt%;
H/C ratio$1:5;API gravity
from6to128)bitumen properties diverse
(sulfur?0:5à10wt%,
nitrogen0.1–1.3wt%;
H=C ratio?1:3à1.6;API
gravity fromà2to148)
bitumen deposits large with uniform
quality;recovery and upgrading plants
on-stream since1970s bitumen deposits small and not
of uniform quality;recovery and
upgrading methods need to be
site-speci?
c
Fig.5.Tar sand deposits in the United States.
Vol.1TAR SANDS229
The sand component is predominantly quartz in the form of rounded or angular particles (11),each of which is wet with a ?lm of water.Surrounding the wetted sand grains and somewhat ?lling the void among them is a ?lm of bitumen.The balance of the void volume in the Canadian sands is ?lled with connate water plus,sometimes,a small volume of https://www.doczj.com/doc/2d12536909.html,ually the gas is air but methane has been reported from some test borings in the Athabasca deposit.Some com-mercial gas deposits were developed in the late 1980s.The sand grains are packed to a void volume of ca 35%,corresponding to a mixture of ca 83wt%sand;the remainder is bitumen and water which constitute ca 17wt%of the tar sands.
3.1.Bitumen.There are wide variations both in the bitumen saturation of tar sand (0–18wt%bitumen),even within a particular deposit,and the visc-osity.Of particular note is the variation of density of Athabasca bitumen with temperature,and the maximum density difference between bitumen and water (70–808C (160–1758F));hence the choice of the operating temperature of the hot-water bitumen-extraction process.
The API gravity of tar sand bitumen varies from 5to ca 108API,depending on the deposit,and the viscosity is very high.Whereas conventional crude oils may have a high (>100MPs ?cP T)viscosity at 408C,tar sand bitumen has a viscosity on the order of 10à100kP s (105–106P)at formation temperature (ca 0–108C),depending on the season.This offers a formidable obstacle to bitumen recovery and,as a result of the high viscosity,bitumen is relatively nonvolatile under conditions of standard distillation (Table 4)(12,13),which in ?uences choice of the upgrading process.
https://www.doczj.com/doc/2d12536909.html,ually >99%of the tar sand mineral is composed of quartz sand and clays.In the remaining 1%,more than 30minerals have been identi ?ed,mostly calciferous or iron-based (14).Particle sizes range from large grains (99.9%?ner than 1000m m)to 44m m (325mesh),the smallest size that can be determined by dry screening.The size between 44and 2m m is referred to as silt;sizes <2m m (equivalent spherical diameter)are clay.
Table 3.Bulk Properties of Tar Sands Property
Alberta Asphalt
Ridge a
P.R.Springs a
Sunnyside
a
Tar Sand Triangle a
Texas Alabama
bulk density,g/cm
3
1.75–
2.19
1.83–
2.50porosity,vol%27–5616–276–3316–289–32
326–25permeability,m 2?10à16b 99–5,9004,905–5,950553–14,9025,265–7,4022,043–7,77731589.9–
6,316
speci ?c heat,J/(?g :C)c 1.46–2.09
thermal conductivity,J/(?s
áCm Tc 0.0071–0.0015a Deposit in Utah.
b
To convert m 2to millidarcies,multiply by 1:013?1012.c
To convert J to cal,divide by 4.184.
230TAR SANDS Vol.1
Clays are aluminosilicate minerals,some of which have de ?nite chemical compositions.In regard to tar sands,however,clay is only a size classi ?cation and is usually determined by a sedimentation method.According to the previous de ?nition of ?nes,the ?nes fraction equals the sum of the silt and clay fractions.The clay fraction over a wide range of ?nes contents is a relatively constant 30%of the ?nes.
The Canadian deposits are largely unconsolidated sands having a porosity ranging up to 45%and good intrinsic permeability.However,the deposits in Utah range from predominantly low porosity,low permeability consolidated sand to,in some instances,unconsolidated sands.In addition,the bitumen prop-erties are not conducive to ?uid ?ow under normal reservoir conditions in either Canadian or U.S.deposits.Nevertheless,where the general nature of the depos-its prohibits the application of a mining technique,as in many of the U.S.depos-its,a nonmining technique may be the only feasible bitumen recovery option (6).
4.Recovery
Oil prices and operating costs are the key to economic development of tar sand deposits.However,two technical conditions of vital concern for economic devel-opment are the concentration of the resource (percent bitumen saturation)and its accessibility,usually measured by the overburden thickness.
The remoteness of the U.S.tar sands is often cited as a deterrent to devel-opment but topography of the site,overburden-to-ore body ratio,and richness of the ore body are also important.In the 1990s context of mining tar sand deposits in the United States,the Utah deposits (Tar Sand Triangle,P.R.Springs,Sunny-side,and Hill Creek)generally have an overburden-to-net pay zone ratio above
Table 4.Distillation Data for Various Bitumens Cut point,8C Athabasca,wt%distilled a
NW Asphalt Ridge,
wt%distilled a
P.R.Springs,wt%distilled a
Tar Sand Triangle,
wt%distilled a
200 3.0 2.30.7 1.7225 4.6 3.3 1.4 2.9250 6.5 4.4 2.4 4.42758.9 5.8 3.8 5.930014.07.5 4.98.432525.98.8 6.812.435018.111.78.015.237522.413.810.118.640026.216.812.522.442529.119.516.026.945033.123.720.028.947537.028.422.532.350040.034.025.035.152542.940.027.338.553844.644.228.040.0538+
55.4
55.8
72.0
60.9
a
Cumulative.
Vol.1
TAR SANDS 231
the 0.4–1.0range,with a lean oil content.On the other hand,the Asphalt Ridge
deposit is loosely consolidated and could be mined using a ripper/front-end loader (without drilling and blasting)at the near-surface location of the deposit.
Recovery methods are based either on mining combined with some further processing or operation on the oil sands in situ (Fig.6).The mining methods are applicable to shallow deposits,characterized by an overburden ratio (ie,overbur-den depth-to-thickness of tar sand deposit)of ca 1.0.Because Athabasca tar sands have a maximum thickness of ca 90m and average ca 45m,there are indi-cations that no more than 10%of the in-place deposit is mineable within 1990s concepts of the economics and technology of open-pit mining.
The bitumen in the Athabasca deposit,which has a gravity on the API scale of 88,is heavier than water and very viscous.Tar sand is a dense,solid material,but it can be readily dug in the summer months;during the winter months when the temperatures plunge to à45 C,tar sand assumes the consistency of concrete.To maintain acceptable digging rates in winter,mining must proceed faster than the rate of frost penetration;if not,supplemental measures such as blasting are required.
4.1.Nonmining Methods.Nonmining (in situ )processes depend on injecting a heating-and-driver substance into the ground through injection wells and recovering bitumen through production wells.Such processes need a relatively thick layer of overburden to contain the driver substance within the formation between injection and production wells (2).
In principle,the nonmining recovery of bitumen from tar sand deposits is an enhanced oil recovery technique and requires the injection of a ?uid into the formation through an injection well.This leads to the in situ displacement of the bitumen from the reservoir and bitumen production at the surface through an egress (production)well.There are,however,several serious constraints that are particularly important and relate to the bulk properties of the tar sand and the bitumen.In fact,both recovery by ?uid injection and the serious constraints on it must be considered in toto in the context of bitumen recovery by nonmining techniques (see Petroleum,enhanced oil recovery).
Heavy oil and bitumen
Mining
In situ
Surface Steam and hot water
Electrical
Combustion
Nuclear
Bacterial Diluents Emulsification Subsurface Thermal Nonthermal
Reverse Stimulation Flood
Wet
Dry
Hydrocarbons Inert gases Carbon dioxide Polymer Caustic Surfactant
polymer
Forward Miscible displacement
Solvent Chemical
Fig.6.Recovery processes.
232TAR SANDS
Vol.1
Vol.1TAR SANDS233 Another general constraint to bitumen recovery by nonmining methods is the relatively low injectivity of tar sand formations.It is usually necessary to inject displacement/recovery?uids at a pressure such that fracturing(parting) is achieved.Such a technique,therefore,changes the reservoir pro?le and intro-duces a series of channels through which?uids can?ow from the injection well to the production well.On the other hand,the technique may be disadvantageous insofar as the fracture occurs along the path of least resistance,giving undesir-able or inef?cient?ow characteristics within the reservoir between the injection and production wells,which leave a part of the reservoir relatively untouched by the displacement or recovery?uids.
In steam stimulation,heat and drive energy are supplied in the form of steam injected through wells into the tar sand formation.In most instances, the injection pressure must exceed the formation fracture pressure in order to force the steam into the tar sands and into contact with the oil.When suf?-cient heating has been achieved,the injection wells are closed for a soak period of variable length and then allowed to produce,?rst applying the pressure cre-ated by the injection and then using pumps as the wells cool and production declines.
Steam can also be injected into one or more wells,with production coming from other wells(steam drive).This technique is effective in heavy oil formations but has found little success during application to tar sand deposits because of the dif?culty in connecting injection and production wells.However,once the?ow path has been heated,the steam pressure is cycled,alternately moving steam up into the oil zone,then allowing oil to drain down into the heated?ow channel to be swept to the production wells.
If the viscous bitumen in a tar sand formation can be made mobile by an admixture of either a hydrocarbon diluent or an emulsifying?uid,a relatively low temperature secondary recovery process is possible(emulsion steam drive). If the formation is impermeable,communication problems exist between injec-tion and production wells.However,it is possible to apply a solution or dilution process along a narrow fracture plane between injection and production wells.
To date(ca1997),steam methods have been applied almost exclusively in relatively thick reservoirs containing viscous crude oils.In the case of heavy oil?elds and tar sand deposits,the cyclic steam injection technique has been employed with some success.The technique involves the injection of steam at greater than fracturing pressure,usually in the10.3–11.0MPa (1500–1600psi)range,followed by a soak period,after which production is commenced(15).
Variations include the use of steam and the means of reducing interfacial tension by the use of various solvents.The solvent extraction approach has had some success when applied to bitumen recovery from mined tar sand but when applied to unmined material,losses of solvent and bitumen are always an obstacle.This approach should not be rejected out of hand because a novel concept may arise that guarantees minimal acceptable losses of bitumen and solvent.
Combustion has also been effective for recovery of viscous oils in moderately thick reservoirs where reservoir dip and continuity promote effective gravity drainage,or where several other operational factors permit close well spacing.
234TAR SANDS Vol.1 During in situ combustion or?re?ooding,energy is generated in the formation by igniting bitumen in the formation and sustaining it in a state of combustion or partial combustion.The high temperatures generated decrease the viscosity of the oil and make it more mobile.Some cracking of the bitumen also occurs, and the?uid recovered from the production wells is an upgraded product rather than bitumen itself.
The recovery processes using combustion of the bitumen are termed for-ward combustion or reverse combustion,depending on whether the combustion front moves with or counter to the direction of air?ow.In either case,burning occurs at the interface where air contacts hot,unburned oil or,more likely,coke. Thus,if the?ame front is ignited near the injection well,it propagates toward the production well(forward combustion).However,if the front is ignited near the production well,it moves in the opposite direction(reverse combustion).In forward combustion,the hydrocarbon products released from the zone of combus-tion move into a relatively cold portion of the formation.Thus,there is a de?nite upper limit of the viscosity of the liquids that can be recovered by a forward com-bustion process.On the other hand,because the air passes through the hot for-mation before reaching the combustion zone,burning is complete;the formation is left completely cleaned of hydrocarbons.In reverse combustion,some hydro-carbons are left in the formation.The theoretical advantage of reverse combus-tion is that the combustion products move into a heated portion of the formation and therefore are not subject to a strict viscosity limitation.However,most attempts to implement reverse combustion in?eld pilot installations have been unsuccessful.In many cases,the failure resulted from the onset of second-ary combustion at the production well.
Using combustion to stimulate bitumen production is attractive for deep reservoirs and in contrast to steam injection usually involves no loss of heat. The duration of the combustion may be short(days)depending on requirements. In addition,back?ow of oil through the hot zone must be prevented or excessive coking occurs(15,16).Another variation of the combustion process involves use of a heat-up phase,then a blow-down(production)phase,followed by a displace-ment phase using a?re–water?ood(COFCAW process).
4.2.Mining Methods.The alternative to in situ processing is to mine the tar sands,transport them to a processing plant,extract the bitumen value, and dispose of the waste sand(17,18).Such a procedure is often referred to as oil mining.This is the term applied to the surface or subsurface excavation of pet-roleum-bearing formations for subsequent removal of the oil by washing,?ota-tion,or retorting treatments.Oil mining also includes recovery of oil by drainage from reservoir beds to mine shafts or other openings driven into the oil rock,or by drainage from the reservoir rock into mine openings driven outside the oil sand but connected with it by bore holes or mine wells.
On a commercial basis,tar sand is recovered by mining,after which it is transported to a processing plant,where the bitumen is extracted and the sand discharged.For tar sands of10%wt/wt bitumen saturation,12.5metric tons of tar sand must be processed to recover1m3(6.3bbl)of bitumen.If the sand contains only5%wt/wt bitumen,twice the amount of ore must be processed to recover this amount.Thus,it is clear that below a certain bitumen concentra-tion,tar sands cannot be processed economically(19).
Vol.1TAR SANDS235 The Athabasca tar sands deposit in Canada is the site of the only commer-cial tar sands mining operations.The Suncor operation(near Fort McMurray, Alberta),started production in1967.The Syncrude Canada project,located 8km away,started production in1978.In both projects,about half of the terrain is covered with muskeg,an organic soil resembling peat moss,which ranges from a few centimeters to7m in depth.The primary part of the overburden,however, consists of Pleistocene glacial drift and Clearwater Formation sand and shale. The total overburden varies from7to40m in thickness,and the underlying tar sand strata averages about45m,although typically5–10m must be discarded because of a bitumen content below the economic cut-off grade of ca 6%wt/wt.
Mining of the Athabasca tar sands presents two principal issues:in-place tar sand requires very large cutting forces and is extremely abrasive to cutting edges,and both the equipment and pit layouts must be designed to operate during the long Canadian winters at temperatures as low asà40 C.
There are two approaches to open-pit mining of tar sands.The?rst uses a few mining units of custom design,which are necessarily expensive,eg,bucket-wheel excavators and large drag lines in conjunction with belt conveyors.In the second approach,a multiplicity of smaller mining units of conventional design is employed at relatively much lower unit costs.Scrapers and truck-and-shovel operations have been considered.Each method has advantages and risks.The ?rst approach was originally adopted by Suncor and Syncrude Canada,Ltd., with Suncor converting to large-scale truck and shovel technology in1993.
In the Suncor pit design,the ore body is divided into two layers(benches), each nominally23m high.The pit?oor and the dividing plane between the upper and lower bench are roughly horizontal,and7300-t/h bucket-wheel excavators are employed as the primary mining equipment(Fig.7).Tar sands loosened from the face of each bench by the bucket-wheels are discharged onto a series of conveyors.The overburden is stripped by an electric shovel that discharges to trucks for removal of the overburden material.Syncrude utilizes a single-bench design with four60-m3capacity draglines as the primary mining equip-ment(Fig.8).The draglines pile tar sands in windrows along the edge of the pit;four60,000-t/h bucket-wheels transfer the tar sands to a system of trunk con-
operations
veyor belts that move the material to the extraction plant.The mining Array Fig.7.Mining with a bucket-wheel excavator,where(à)represents the ultimate size of the dyke.
at the two plants differ by choice of the primary mining equipment;the bucket-wheel excavators sit on benches,whereas the draglines sit on the surface.
Bucket-wheel excavators use units having a 10m dia digging wheel on the end of a long boom.Each wheel has a theoretical capacity of 8700t/h,but the average output from digging is about 4500t/h.At the rate of 122,000t/d,tar sand can be transferred from mine to plant by a system of 152-cm wide con-veyor belts and 183-cm trunk conveyors,operating at 333m/min.The bucket-wheel excavators are supplemented by front-end loaders used to dig overburden and load it through twin chutes onto ca 135t capacity trucks.Additional equip-ment is used for maintaining the haul roads and for spreading and compacting the spoiled material.Overburden may be stripped with 14-m 3hydraulically oper-ated shovels and a ?eet of ca 135t trucks.
Draglines are equipped with a 71-m 3bucket at the end of a 111-m boom and can be employed to dig both a portion of the overburden,which is free-cast into the mining pit,and the tar sand,which is piled in windrows behind the machine.Bucket-wheel reclaimers,similar to bucket-wheel excavators,load the tar sand from the windrows onto conveyor belts which transfer it to the plant.
5.Processing
5.1.Hot-Water Process.The hot-water process is the only successful
commercial process to be applied to bitumen recovery from mined tar sands in North America as of 1997(2).The process utilizes linear and nonlinear varia-tions of bitumen density and water density,respectively,with temperature so that the bitumen that is heavier than water at room temperature becomes lighter than water at 808C.Surface-active materials in tar sand also contribute to the process (2).The essentials of the hot-water process involve conditioning,separation,and scavenging (Fig.9).
In the conditioning step (mixing or pulping),tar sand feed is heated and mixed with water to form a pulp of 60–85%solids at 80–908C.First the lumps of tar sand as mined are reduced in size by ablation,ie,successive layers of lump are warmed and slough off,revealing cooler layers.The pulp is mechanically mixed,reacts with any chemicals added,is further heated to the process tem-perature,and is conditioned by open-steam heating in a horizontal
rotating
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238TAR SANDS Vol.1 drum.With regard to equipment scale-up,conditioning is essentially a heat-transfer process.The ef?uent from the conditioning drum is screened to remove tramp material or lumps that were not suf?ciently reduced in size.The screened pulp is mixed with any added water,adjusted to the proper consistency for pumping as described below,and sent to the separation cell.
The separation cell is an open vessel with straight sides and a cone bottom. Mechanical rakes on the bottom move the sand toward the center for discharge. Wiper arms rotating on the surface push the froth to the outside of the separa-tion cell,where it over?ows into launders for collection.The cell acts like two set-tlers,one on top of the other.In the lower settler sand settles down;in the upper settler,bitumen?oats.The bulk of the sand in the feed is removed from the bot-tom of the separation cell as tailings.A large portion of the feed bitumen?oats to the surface of the separation cell and is removed as froth.A middlings stream consists mostly of water,with some suspended?ne minerals and bitumen parti-cles.A portion of the middlings may be returned for mixing with the conditioning drum ef?uent in order to dilute the separation cell feed for pumping.The remain-der of the middlings is called the drag stream,which is withdrawn from the separation cell to be rejected after processing in the scavenger cells.
Tar sand feed contains a certain portion of?ne minerals that,if allowed to build up in concentration in the middlings,increases viscosity and eventually disrupts settling in the separation cell.The drag stream is required as a purge in order to control the?nes concentration in the middlings.The amounts of water that can enter with the feed and leave with the separation cell tailings and froth are relatively?xed.Thus,the size of the drag stream determines the makeup water requirement for the separation cell.
The third step in the hot-water process is scavenging.Depending on the drag-stream size and composition,enough bitumen may leave the process in the drag stream to make another recovery step economical.Froth?otation with air is usually employed,and the scavenger froth is combined with the separation cell froth to be further treated and upgraded to synthetic crude oil. Tailings from the scavenger cell join the separation cell tailings stream and go to waste.Conventional froth-?otation cells are suitable for this step.
Froth from the hot-water process may be mixed with a hydrocarbon diluent, eg,coker naphtha,and centrifuged.The Suncor process employs a two-stage cen-trifuging operation,and each stage consists of multiple centrifuges of conven-tional design installed in parallel.The bitumen product contains1–2wt% mineral(dry bitumen basis)and5–15wt%water(wet diluted basis).Syncrude also utilizes a centrifuge system with naphtha diluent.
An attempt has been made to develop the hot-water process for the Utah sands(Fig.10)(20).With oil-wet Utah sands,this process differs signi?cantly from that used for the water-wet Canadian sands,necessitating disengagement by hot-water digestion in a high shear force?eld under appropriate conditions of pulp density and alkalinity.The dispersed bitumen droplets can also be recov-ered by aeration and froth?otation(21).
The hot-water separation process involves extremely complicated surface chemistry with interfaces among various combinations of solids(including both silica sand and aluminosilicate clays),water,bitumen,and air.The control of pH is critical.The preferred range is8.0–8.5,achievable by use of any of the mono-
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Fig.11.Aqueous zones in tailings pond.
valent bases.Polyvalent cations must be excluded because they tend to?occulate clays and thus raise viscosity of the middlings in the separation cell.
One problem resulting from the hot-water process is disposal and control of the tailings.Each ton of oil sand in place has a volume of ca0.45m3,which gen-erates ca0.6m3of tailings and gives a substantial volume gain.If the mine pro-duces200,000t/d of oil sand,volume expansion represents a considerable solids disposal problem.
Environmental regulations in Canada and the United States do not allow the discharge of tailings streams into the river,onto the surface,or onto any area where contamination of groundwater domains or the river may occur.The tailings stream is essentially high in clays and contains some bitumen;hence the need for tailings ponds,where some settling of the clay occurs(Fig.11).In addi-tion,an approach to acceptable reclamation of the tailings ponds must be accom-modated at the time of site abandonment.Problems may be alleviated somewhat by the development of process options that require considerably less water in the sand–bitumen separation step.Such an option would allow a more gradual removal of the tailings ponds.
5.2.Cold-Water Process.The cold-water bitumen separation process has been developed to the point of small-scale continuous pilot plants.The pro-cess uses a combination of cold water and solvent.The?rst step usually involves disintegration of the tar sand charge,which is mixed with water,diluent,and reagents.The diluent may be a petroleum distillate fraction such as kerosene and is added in a ca1:1weight ratio to the bitumen in the feed.The pH is main-tained at9–9.5by addition of wetting agents and ca0.77kg of soda ash per ton of tar sand.The ef?uent is mixed with more water,and in a raked classi?er the sand is settled from the bulk of the remaining mixture.The water and oil over-?ow the classi?er and are passed to thickeners,where the oil is concentrated. Clay in the tar sand feed forms emulsions that are hard to break and are wasted with the under?ow from the thickeners.
The sand reduction process is a cold-water process without solvent.The objective is removal of sand to provide a feed suitable for a?uid coking process. In the?rst step,the tar sand feed is mixed with water at ca208C in a screw conveyor at a ratio of0.75–3t/t tar sand(lower range preferred).The mixed pulp from the screw conveyor is discharged into a rotary-drum screen,which
Vol.1TAR SANDS241 is submerged in a water-?lled settling vessel.The bitumen forms agglomerates that are retained by an840-m m(20-mesh)screen.These agglomerates settle and are withdrawn as oil product.The sand readily passes through the840-m m (20-mesh)screen and is withdrawn as waste stream.Nominal composition of the oil product is58wt%oil(bitumen),27wt%mineral,and15wt%water.
A process called spherical agglomeration closely resembles the sand-reduction process.Water is added to tar sands and the mixture is ball-milled. The bitumen forms dense agglomerates of75–87wt%bitumen,12–25wt% sand,and1–5wt%water.
5.3.Solvent Extraction.An anhydrous solvent extraction process for bitumen recovery has been attempted and usually involves the use of a low boil-ing hydrocarbon.The process generally involves up to four steps.In the mixer step,fresh tar sand is mixed with recycle solvent that contains some bitumen and small amounts of water and mineral.Solvent-to-bitumen weight ratio is adjusted to ca0.5.The drain step consists of a three-stage countercurrent wash.Settling and draining time is ca30min for each stage.After each extrac-tion step,a bed of sand is formed and the extract drained through the bed until the interstitial pore volume of the bed is emptied.The last two steps of the pro-cess are devoted to solvent recovery from the solids.Although solvent extraction processes have been attempted and demonstrated for the Athabasca,Utah,and Kentucky tar sands,solvent losses in?uence economics of such processes and they have not yet been reduced to commercial practice.
6.Bitumen Conversion
Bitumen is a hydrogen-de?cient oil that is upgraded by carbon removal(coking) or hydrogen addition(hydrocracking)(2,4).There are two methods by which bitumen conversion can be achieved:by direct heating of mined tar sand and by thermal decomposition of separated bitumen.The latter is the method used commercially,but the former has potential for commercialization(see F UELS, SYNTHETIC).
6.1.Direct Heating of Mined Tar Sand.An early process(Fig.12) involved a coker for bitumen conversion and a burner to remove carbon from the sand(22).A later proposal suggested that the Lurgi process might have applicability to bitumen conversion(23).A more modern approach has also been developed which also cracks the bitumen constituents on the sand(24). The processor consists of a large horizontal rotating vessel which is arranged in a series of compartments,a preheating zone,and a reaction zone.
Direct coking of tar sand using a?uid-bed technique has also been tested. In this process,tar sand is fed to a coker or still,where the tar sand is heated to ca4808C by contact with a?uid bed of clean sand from which the coke has been removed by burning.Volatile portions of the bitumen are distilled,whereas non-volatile material is thermally cracked,resulting in the production of more liquid products and the deposition of a layer of coke around each sand grain.Coked solids are withdrawn down a standpipe,?uidized with air,and transferred to a burner or regenerator,operating at ca8008C where most of the coke is burned off the sand grains.The clean,hot sand is withdrawn through a standpipe.Part
京剧行当说课稿 赤峰红山中学白泳鑫尊敬的各位领导、老师： 大家好！ 我今天说课的题目是《京剧行当》，请各位老师批评指正。 首先是教材分析，京剧行当是人音版教材八年级下册京腔昆韵中的拓展延伸课。京剧是中国的国粹，是我国的艺术瑰宝。在我国众多戏曲中，京剧最具有民族性、群众性，代表着中华戏曲文化主流。京剧艺术是博大精深的，其中蕴含的文化不胜枚举。凭借一节课时无法把整体的京剧艺术介绍全面，所以只选出京剧所涉及的一个小点来进行讲解。我所选择的这个点是京剧的行当介绍，因为京剧的行当实践性较强，可以让学生参与体会，进而了解这其中的艺术。 第二、学情特点，我所面对的学生是初中阶段的学生，这一阶段的学生有很强的求知欲，模仿能力较强。让学生通过实践可以更好的理解京剧的行当。 第三、教学理念，本节课是以模仿实践为主的欣赏课 第四、教学目标， 1.学习了解京剧行当，再现一些经典的京剧曲目。 2.通过对京剧行当知识的了解与曲目场景的再现，创设出师生共同参 与的体验活动。 3.通过学习京剧，让学生了解京剧的博大精深，并热爱国粹，喜爱中 国文化。 第五、教学重点难点 教学重点是让学生了解京剧行当，体会京剧的魅力。教学难点是通过体验京剧行当，对京剧功能的再现（实践、体验）。 第六、教学过程 一、导入过程，首先给学生表演一段音配像京胡名曲《夜深沉》，让学生听旋律，观察画面，引出京剧内容，进而往主题上相靠。 二、新课教学 1、介绍京剧定义 首先我会给学生介绍京剧的定义，京剧是中国的国粹，它是由汉调和徽调结合，并吸收了秦腔、昆曲等地方戏曲的精华而成，至今已有两百多年的历史了，表演形式分为唱、念、做、打四种艺术形式，京剧剧目丰富、行当齐全，已被联合国教科文组织列入“人类口头与非物质文化遗产名录”。 2、介绍京剧四大行当 在学生有了一定的了解之后开始详细的介绍京剧的四大行的。 一）介绍“生”角定义，除花脸和丑角以外男性正面角色的统称。性别角色男，分类分为文老生、文小生、红生、武生。代表曲目有《三岔口》。然后欣赏《三岔口》的经典片段。 询问学生视频片段中有哪些伴奏乐器？鼓、钹。让学生体会京剧中伴奏乐器速度的作用，然后带领学生实践，之后练习亮相动作，配合鼓的节奏咚咚嚓一起做出，完成实践环节。 二）介绍“旦”角定义，女性正面角色的统称。角色性别为女，行当分类分为青衣，代表人物白素贞；花旦，代表人物春草；刀马旦，代表人物穆桂英；老旦，代表人物佘太君。这些都是按照年龄、身份、性格表演特点而分的。然后欣赏旦角的经典片段《卖水》，欣赏之后让学生参与剧中经典场景。让学生体会“旦”
大学学生简单自我介绍 大学学生简单自我介绍 第一篇： 大学学生简单自我介绍 你好!我名字叫haoord，我22岁。来自xx，一个美丽的文化城市，现在就读于xx大学。一般来说，我是一个勤奋的学生，尤其是做我感兴趣的东西。我会尽我最大的努力，无论是多么困难的事情，都要完成它。在我读大二的时候，我发现网站设计很有趣，所以我很努力的学习。通过两个月的时间，为自己制作了一个网页。我是我们班第一个拥有自己主页的人。 此外，我是一个很有毅力的人。我坚持每天跑步，不管什么天气。在我的业余时间，我喜欢篮球，网球和中国象棋。英语也是我的最爱。我经常去英语角练习我的英语口语，写作文，以改善我的写作能力。但我知道我的英语不够好，我会继续学习。谢谢! 第二篇： 简单的英文自我介绍 mature，dnami and honest。思想成熟、精明能干、为人诚实。 exellent abilit of sstematial management。有极强的系统管理能力。 be elegant and ith nie personalit。举止优雅、个人性格好。 ith good managerial skills and organizational apabilities。有良好的管理艺术和组织能力。
the main qualities required are preparedness to ork hard, abilit to learn, ambition and good health。主要必备素质是吃苦耐劳精神好、学习能力优、事业心强和身体棒。 ith job searhes taking longer, there are more jobseekers bumping up against their severane deadline 。随着找工作花的时间长了，越来越多的求职者发现已逼近他们找工作的明确限期，或者 仅仅是他们心理上的限期，即主观上告诉自己现在本该已找到工作 的。 a popular question that i hear often is ho long ou should hold out for that dream jo b before moving to plan b。我常听到的一个问题就是： 人们应该为梦想中的工作坚持多久才退而执行另外的计划呢? the anser is different for everone:答案因人而异，下面一些可能的影响因素： hat is our time urgen? have ou run the atual numbers on our ash ushion runs out? the shorter the time ou have, the ider our net has to be. even if our dream pan industr funtional area is hiring, hen ou have a short timeframe, ou need to have multiple searhes ell undera。你最紧迫的事是什么?你有没有计算过你目前的储蓄可以支撑多少天?时间越急，你撒的网就必须越广。即使你心仪的公司、行业、领域正在招人，考虑到时间紧促，你也应该同时多处留意。 hat is our risk appetite? some people are energized b putting all their fous on their passion. some people ould be
关于运动的英语演讲稿 篇一：英语演讲运动sports 英语演讲运动sports All over the world people enjoy sports. Sports help to keep people healthy and happy, and to live longer. Sports change with the seasons. People play different games in winter and summer. Swimming is fun in warm weather, but skating is good in winter. Some sports are so interesting that people everywhere go in for them. Football, for example, has spread around the world. Swimming is popular in all countries near the sea or in those with many rivers. Some sports or games go back thousands of years, like running or jumping. Chinese wushu, for example, has a very long history. But basketball and volleyball are rather new. People are inventing new sports or games all the time. Water skiing is one of the newest in the family of sports. People from different countries may not be able to understand each other, but after a game together they often become good friends. Sports help to train a
生、旦、净、丑是京剧的四大行当。 1、生行 生行是扮演男性角色的行当，在京剧中的地位非常重要。生行包括老生、小生、武生、红生、娃娃生等几个门类。除红生和勾脸武生以外，生行一般都是素脸，内行术语称为“俊扮”，即扮相都是洁净俊美的。 ①老生又称“须生”、“正生”、“胡子生”。一般都是富有正义感的男性中年或老年人物。人物形象以挂“黑髯口”（黑胡子）为主。按照表演艺术特点的不同，老生又分为安工老生、衰派老生和靠把老生。安工老生，又称“唱切老生”、“王帽生”、大部扮演帝王、书生一类人物，以唱功为主，在舞台上安详稳重，动作较少，故称“安工”，如《上天台》中的汉光武帝刘秀、《捉放曹》中的陈宫等。衰派老生，又称“做功老生”。“做工老生”，大都扮演衰老或精神状态衰颓的人物，以做功为主，故称“衰派”，如《四进士》中的宋土杰、《卖马》中的秦琼、《坐楼杀惜》中的宋江等。靠把老生，大都扮演武将一类的人物，由于扎靠（戴盔披甲）、使用刀枪把子（剧中人使用的兵器）而得名，加《定军山》中的老将黄忠、《战太平》中的花云、《镇潭州》中的岳飞等。无论是哪类老生，都是以唱为主，全用本嗓。安工老生要唱的悠扬婉转，衰派老生要唱的悲愤颓唐，靠把老主要唱的激昂慷慨。另外，京剧史上有一些老生演员，文戏、武戏都擅长，唱功戏、做功戏、靠把戏都能演，后来就把这种戏路宽的老生演员称为“文武老生”，如程长庚、谭鑫培等。 ②小生主要扮演青少年男子，化妆不戴胡须，扮相清秀、英俊。小生演唱用尖音假嗓，念白兼用真假嗓。小生使用的假嗓与旦角不同，小生的唱法应该刚、劲、宽、亮，听起来声音清跪但不柔媚，刚健但不粗野。根据人物性格、身分的不同特点，小生又分为袍带小生、扇子生、翎子生、穷生和武小生。袍带小生，又称“纱帽小生”，扮演做官的青年男子，头戴纱帽是其主要标志，这些角色大部分是文人，如《玉堂春》中的王金龙、《奇双会》中的赵宠、《陈三两爬堂》的陈魁等。扇子生，多扮演年青的书生、风流儒雅的公子，手拿扇子，头戴文生巾，身穿褶子，所以又称“褶子生。”扇子是帮助角色表现风流潇洒、文质彬彬的一种特殊道具。如《拾玉镯》中的傅朋、《西厢记》中的张君瑞等。翎子生，又称“雉尾生”，头插翎子（雉尾）是其主要标志，大都扮演武将或文武兼备的人物。演翎子生要有武功，凭工架、舞蹈，用翎子耍出许多舞蹈动作。如《群英会》中的周瑜、《吕布与貂蝉》中的吕布、《穆柯寨》中的杨宗保等等。穷生，大部扮演落魄不第的文人、书生，“表演上特别注重做功，”以表现人物的酸腐气为主，习惯于把鞋后帮踩倒在脚下，以示其潦倒之状，故又称“鞋皮生”，身穿富贵衣是其主要标志。富贵衣，是补缀有许多五颜六色的补丁的青褶子，意思是说这些人现在虽然很穷，衣着褴楼，但将来仍要腾达，故有“富贵衣”之名。如《棒打薄情郎》中的莫稽、《连升店》中的王明芳等。武小生，大多扮演年青英武的人物，表演著重武功，也兼重唱功、念白和做功。从武打功夫上看，武小生与武生差不多，但是唱与念全用小生方法。如《八大锤》中的陆文龙、《借赵云》中的赵云、《石秀探庄》中的石秀等。 ③武生扮演擅长武艺的青壮年男子，分为长靠武生和短打武生两类，俗称“墩子武生”、“撇子武生”，“墩子”是指穿厚底靴子，“撇子”是指穿薄底靴子。长靠武生扎大靠，武打、工架并重，如《长坂坡》中的赵云、《战冀州》中的马超、《挑滑车》中的高宠等。短打武生身穿紧身短装。偏重武打特技，如《三岔口》中的任堂惠、《十字坡》中的武松、《夜奔》中的林冲等。扮演中老年英代人物的称武老生，如《百凉楼》中的吴祯、《剑峰山》中的邱成等。武生还兼演部分勾脸戏（武净戏），如《铁笼山》中的姜维、《拿高登》中的高登等。猴戏中的孙悟空一般也由武生扮演。 ④红生指勾红脸的老生，主要扮演关羽、赵匡胤等角色，演唱嗓音高亢浑厚，表演具
大学生个人简短自我介绍范文 大学生个人自我介绍范文篇一 各位面试老师好，我叫xxx，是医科大学医学检验系的学生，将毕业并获得学士学位。医学检验是一门对动手能力要求较高的学科，所以，在校期间，除了医学基础课和专业课理论的学习，我们还被安排了大量的实验课，其中临床检验、微生物检验、生化检验、免疫学检验等专业课，他们的实验课比理论课还要多，这些既使我们对理论有了更深的理解和掌握，更重要的是使我们有了熟练的动手操作能力。我在随后的xx市第一中心医院检验科实习期间，很快就得到了代教老师的认可和信任，而肯放开手让我独立操作仪器和独立进行实验，我也就更加积极主动地去做得更好，遇到不明白的问题及时地向老师请教。等到实习结束时已经熟知了检验科的工作流程和具备了大多实验的独立操作能力。 最后我由衷的希望您能够给我一次展现才华的机会，能让我加入贵单位。当然了，刚刚跨出大学校门的我在工作经验和社会阅历方面显得捉襟见肘，但我深信天道酬勤，我愿意从最一点一滴做起，我相信经过加倍努力，并在工作中不断学习，我相信一定能赢得您和大家的认可。 大学生个人自我介绍范文篇二 我是***学院***专业的学生。 大学四年中，我各方面的能力都得到了发展，可以说，经过大学四年的学习，我已经具备了适应社会工作的能力。这学期即将画上了句号，就是毕业了。回首往事，至少可以自信地说一声“我没有虚度”。有必要对这四年做个自我评定。 在思想上，我要求上进，一直以乐于助人为已任，多次参加青年志愿者活动。尊敬师长，团结同学，为自己的学习和生活创造了良好的环境。 在学习上，我刻苦努力，孜孜不倦，争取着大学那美好的时光去学习。大学四年，不光使我学到了许多知识，也使我懂得了学习的方法。正是利用这种方法，在除学校开设的课程外，我还自学了网络数据库、网页制作、平面设计等知识，很好地充实了自己的业余生活，并为自己的将来打下良好的基础。到目前为止，我已掌握了本专业的基础知识和有关网络的基本知识。除此之外，对计算机的爱好让我对计算机有一定的了解，并具有一定的编程能力。工作方面，我参与了
关于科技的英语演讲稿—Technologyand thepresenceofstudents,ladiesandteachers,everyone!iw aspreparedintervalsofcloudtoday,inhonorhereentitled“te chnologyandfuture”speech,iamveryproudofboth,butsomeune ase.inrecentyears,wehaveseenourgreatmotherland,thecause oftherapiddevelopmentoftechnology,whichallowmetoachines eifeelveryproud.rememberthatlongago,cellphoneusealmostt heonlyone,whichiscalled,butafewyearsago,cellphoneshasun dergonegreatchanges,notonlylookmorebeautiful,butalsouse more,youcanusethephonestotakepictures,meetings,internet ,textmessages,etc.aseriesofthingsthatitheirlifemoreconv enient,soiammoreawareofthestrengthofthetechnology,butia mjustafledglingsstudents,“technology”asthewordalsoawa reofthelimited,iamunabletousesomeverydifficulttheorytoe laboratetechnologyxuanji,norighttoworkontheireldersican promiseofthetechnologyblueprint.butiamwillingtouseastud ent’sperspectivetotheimaginetechnologyandthefuture.fromgene ticengineering“isaliveprinces”dream,nano-technology“
英语演讲稿：我喜欢运动 my favourite sport good afternoon, ladies and gentlemen. it’s my great pleasure to be here sharing my speech with you. today my topic is my favourite sport. look at my healthy skin , oh! can you guess which sport i like best? yes,it's swimming !that's why i look so handsome. when i was only 5 years old, i began to learn how to swim and i like it. i think swimming is an interesting sport and it's exciting. it's also a good way to keep fit . every summer, i go to swimming school . my parents say i’ll have a good health if i insist swimming in a right way. and i can grow taller if i go to swim often. so i always ask my coach some questions on swimming and he always helps me a lot. i can swim so well and i can swim breaststroke, backstroke and freestyle. if you also like swimming, join me! thank you! 我最喜欢的运动
京剧四大行当
京剧四大行当——生、旦、净、丑 行当是我国传统戏曲一种重要的表演艺术手段，各地方戏曲剧种都有行当的划分。 京剧原分十大行当：一末二净三生四旦五丑六外七小八贴九夫十杂；后概括为五大行当：生旦净末丑；最后归并为“生旦净丑”四大行当。 除这四行外，尚有几类次要的角色，如武戏中的配角“武行”和“觔斗行”，以及跑龙套的“流行”，所以也有七行之说，即“生旦净丑，武流觔斗”。其他地方剧种的行当和京剧大同小异，现我们就京剧的行当作一简单的介绍—— 1、生行 生行，指戏曲剧目中的男性形象，以面部化妆为俊扮为其特点。根据其年龄、身份的不同可以分为老生、小生、武生等不同的种类。 老生：指生行中的中年或老年形象，以戴胡须（即髯口）为其特点。又根据其不同的表演特点，分为唱功老生、做功老生和靠把老生三类。 小生：指生行中的年轻人形象，根据不同的表演特点，可分为扇子生、纱帽生、雉尾生、穷生、武小生等类别。（《群英会》的周瑜是雉尾小生） 武生：指生行中身具武艺的男性形象，又有长靠武生（表现大将）和短打武生（表现绿林英雄）之分。前者扎大靠，重工架；后者穿紧身衣服，重翻打。 （如《长坂坡》之赵云) 红生：有时将其归入武生行，指勾红脸的身具武艺的男性形象，最典型的是 关羽和赵匡胤。 2、旦行 旦行，指戏曲中的女性形象，可分为青衣、花旦、刀马旦、武旦、老旦、彩旦等类别。 青衣：又叫“正旦”，多表现那些端庄稳重的中青年妇女，以唱功见长，如《铡美案》中的秦香莲，《二进宫》中的李艳妃等。 花旦：多表现那些年轻活泼俏俐的小家碧玉或丫鬟，以做功和念白见长，如《西厢记》中的红娘，《拾玉镯》中的孙玉姣等。 武旦：表现那些身俱武艺的江湖女子或神怪精灵，多穿紧身衣服，表演上重翻打，如《白蛇传》中的青蛇、《十字坡》的孙二娘等。
大学生的简单自我介绍 大学生的简单自我介绍1 各位老师、同学，大家好，我叫宋轩，1988年6月6日出生，20岁，来自山东，齐鲁大地给了我直爽的性格，但又不失稳重，之后不远千里来到南京这个城市求学。 来到大学学习的事实和我的理想有很大的出入，难免有些郁闷，但在一段时刻后，我认清了事实，很看互联网专业。”21世纪是网联网的世纪。”这句话一点都不假，随着互联网的展，它为21世纪插上了腾飞的翅膀。之后在不断的培养兴趣过程中，我开始对互联网产生兴趣，今后的四年，我将在不断的学习进步中度过的。 “十年磨砺锋利出，宝剑只待君来识”。再苦再累，我都愿意一试，“吃得苦中苦，方为人上人”，在以后的学习生活中，我必须会是一位尽自己的发奋、过一个充实而又好处的大专生活。 大学生的简单自我介绍2 尊敬的领导、敬爱的老师、亲爱的同学们、朋友们：大家好! 踏着清爽的秋风，吻着醉人的菊香，在这丰收的季节，我从千里之外的辽东来到了素有天堂美誉之称的杭州，跨进了梦寐以求的浙江商业学院的大门，开始了我的大学之梦的旅程。 当我踏进这所高等学府的大门时，看到老师们热情的手
臂，温暖的笑容，听到新同学们的欢歌笑语和亲如弟兄姐妹般的问候，让我周身的血液开始沸腾，心跳也开始加速。这是为什么呢?正因那里就是我人生的一个最最重要的转折点，一个让我圆梦的地方!读大学是我们每一个年轻人孜孜以求的梦想，这个梦从我的儿时就开始了。那时候虽然我还不懂得什么是理想、什么是奉献、什么是职责，可我羡慕科学家、羡慕作家、羡慕宇航员、羡慕一切有作为的精英干将。渴望自己将来也能够像他们一样，成为他们其中的一员，为伟大祖国的建设事业做出自己的贡献。历经十二年的中小学的读书过程，让我逐渐明白了一个道理，那就是：要想成功，一要有聪睿的头脑，优良的道德品质，二要有渊博的知识，丰富的学识。三是要有健康的体魄，宽旷的胸怀。最后就是要有上天赐予的机遇。而机遇是给有准备的人准备的，这个准备就是第一、第二和第三的资料，那么大学就是我们做这个准备的最好地方。只有做好了第一、第二和第三的准备工作，我们才能在机遇到来之时，从容不迫地伸出我们的双手去迎接他、应对他，而被他所接纳、所包容。我们也就能在自己胜任的舞台上，演好自己的主角。以不负家乡父老的殷殷期望，老师的辛苦栽培。 愚者错失机会，智者善抓住机会，成功者创造机会，机会只是给准备好的人。机遇真是“神奇”，它能给“山穷水尽疑无路”的人带来“柳暗花明又一村”的喜悦;它能让商人散尽千金“还复重来”……。“机遇”说起来很神奇，其实它经常出此刻我们的身边，而智者能发现它、利用它走向
大学简短幽默自我介绍_大一新生开 学有趣的自我介绍 幽默是人类独有的品质、能力和交际方式。大学生用幽默的话语来做自我介绍可以得到同学们的好感。下面是小编为大家整理的大学简短幽默自我介绍，仅供参考。 大学简短幽默自我介绍篇一 本人外表平平，在此就不细说了，大街上随便抓个人都会有和我的相识之处。性格还好，中庸是我的理想，但迫于社会现实所逼，经常做出一些左倾和右倾的事情，于是乎导致我现在没多大成就，除了找到几个我十分玩命的朋友，我感觉自己还是相当孤独的。不过只有高处的人才会感到孤独，与我自身的空虚寂寞——也就是年轻人特有的茫然无关。 我深刻感受到自己的善良，于是我坚定好人有好报，因为我无意中的善行为我赢来了许多朋友，感觉是上天的馈赠，但偶然我也觉得自己很无情，尤其是见到四肢健全、身强力壮的乞丐，我都极力装没看到。作为一男生，我又非常要脸皮，非常要面子，而且有点过火了，可能我的脸皮特别厚，所以也特别要面子，不
能让我的脸皮受一点损害。呵呵!差不多了，这个人很简单，又不是大人物，没太多讲的。 大学简短幽默自我介绍篇二 大家好，秋天来了，我也来了.我叫某某.很高兴能站在这里跟大家做个自我介绍.我很喜欢笑，妈说我出生的时候是笑着生出来的.为这事中科院的找我好几回，非要给我做个全面检查.我没同意，我说除非你们的人当中有谁比我的眼睫毛张得好看，嘿嘿，大家注意到没有.我的眼睫毛很好看哦，不信? LOOK!如果现在你看不清楚，没有关系，下课了找我啊，我很愿意交朋友，因为我十分开朗，交到我这个朋友，免费让你看个够，赶快行动吧!谢谢! 大学简短幽默自我介绍篇三 大家好我叫XXX 我是一个超级活泼的人噢~` 不要被我看似文静或者内敛的外面给欺骗了噢~我的胜任座右铭是：态度决定一切。因为我觉得一个人到底会不会成功，态度才是最关键的因素。我喜欢看什么什么书~ 曾经记得那里有这么一句话~《要牛逼一点的》我觉得它是能给我的人生一点启示的话所以拿出来与大家分享，希望大家也能从中得到一点帮助。
英语比赛演讲：我喜欢运动-英语演讲稿 my favourite sport good afternoon, ladies and gentlemen. it’s my great pleasure to be here sharing my speech with you. today my topic is my favourite sport. look at my healthy skin , oh! can you guess which sport i like best? yes,it’s swimming !that’s why i look so handsome. when i was only 5 years old, i began to learn how to swim and i like it. i think swimming is an interesting sport and it’s exciting. it’s also a good way to keep fit . every summer, i go to swimming school . my parents say i’ll have a good health if i insist swimming in a right way. and i can grow taller if i go to swim often. so i always ask my coach some questions on swimming and he always helps me a lot. i can swim so well and i can swim breaststroke, backstroke and freestyle. if you also like swimming, join me! thank you! 我最喜欢的运动
简单的大学生自我介绍范文 各个大学的大一新生们，已经开始露露开学了，开学就是面临着新的生活了，在进入校园后免不了和大家分班级，每一个人都要上台在全班同学面前做自我介绍，这个时候大家一定要明白有很东西是不可以说的，否则会让自己交不到朋友，甚至会让同学们鄙视，下面就为大家分享四个不能介绍的点，想要了解的朋友们，赶紧与来看看吧! 一、爱好 ___喜欢吃什么和玩什么 相信有不少的同学，在介绍自己时都会说自己的爱好，当自己向大家说喜欢吃什么和玩什么时，肯定是不合适的，大家要明白跟初高中时的介绍是不一样的，大学的四年生活与自己关系最密切的还是室友，除了寝室的几个人，与其他的同事关系根本不会密切，大家在介绍自己时，就没有必要在台上说的没完没了，这样做只会浪费大家的时间，给同学们留下不好的印象;因此，大一新生在介绍自己时，千万不要说一些无关紧要的事情，最好控制在3-5分钟最好。 二、关于爸妈的事情最好不要说
有很多大一新生，在介绍自己时，都会介绍自己的爸妈，以及自己的成长环境;大家在介绍自己时要明白，那些愿意介绍爸妈工作的人，一般家里的条件都不是太差的，不管自己的爸妈是企业家，还是干部工作者，只有是强调了爸妈的成就，这些话的潜在意思就是告诉大家，你的家庭条件好，财富底子厚，会给大家一种不好的感觉，甚至会起到相反的作用，试想那些家庭普通的同事，怎么敢靠近你这个富人子弟，相信大部分人都不愿意和喜欢炫耀的人相处;因此，大一新生在介绍自己时，不要介绍关于爸妈的背景。 三、平时成绩好高考发挥失利的话不要说 也有些同学，上台后介绍自己时，会说一些关于自己高中成绩的事情，自己平时的成绩有多好，自己高考发挥失利，只考了多少多少分，造成了自己和大家成为同班同学，当你向大家说这些话时，大家就会认为你是在看不起人家，看不起现在的学校和班级，相信大部分同学都会对你产生反感;大家要明白不管自己以前怎么样，在进入大学后就是新的开始，大家又重新站在统一起跑线上了，明白这个道理大家才会珍惜和你之间的关系;因此，大家不要随便介绍，平时成绩好高考发挥失利的事情。 四、自己的感情状态不要说
关于运动英语演讲稿
关于运动英语演讲稿 【篇一：英语演讲运动sports】 英语演讲运动sports all over the world people enjoy sports. sports help to keep people healthy and happy, and to live longer. sports change with the seasons. people play different games in winter and summer. swimming is fun in warm weather, but skating is good in winter. some sports are so interesting that people everywhere go in for them. football, for example, has spread around the world. swimming is popular in all countries near the sea or in those with many rivers. some sports or games go back thousands of years, like running or jumping. chinese wushu, for example, has a very long history. but basketball and volleyball are rather new. people are inventing new sports or games all the time. water skiing is one of the newest in the family of sports. people from different countries may not be able to understand each other, but after a game together they often become good friends. sports help to train a persons character. one learns to fight hard but fight fair, to win without pride and to lose with grace. (胜不骄,败不馁) [点评] 运动是人人皆知的话题。作者从运动的种类到运动项目的历史作了一番描述，在结尾段中强调了运动的好处，观点显而易见。语言简单明了，描述、议论清楚。 [参考译文]
关于科技的英语演讲稿—Technology 目录 第一篇：英语演讲稿—Technology and future 第二篇：英文科技转让协议范本Technology assignment agreement 第三篇：关于科技的英语演讲稿—Technologyandfuture 第四篇：演讲稿 modren Technology or traditional value 第五篇：what Technology brought us 科技给我们带来的影响正文 第一篇：英语演讲稿—Technology and future the presence of students, ladies and teachers： everyone! i was prepared intervals of cloud today, in honor here entitled Technology and future speech, i am very proud of both, but some unease. in recent years, we have seen our great motherland, the cause of the rapid development of Technology, which allow me to a chinese i feel very proud. remember that long ago, cell phone use almost the only one, which is called, but a few years ago, cell phones has undergone great changes, not only look more beautiful, but also use more, you can use the phones to take pictures, meetings, internet, text messages, etc.
老生介绍 老生又叫须生，或胡子生。因为老生都挂胡子。胡子在京剧里的专门名词叫“髯口”。老生除了须生和胡子生，还有一个名词叫正生，表示严肃端庄的意思。老生主要扮演中年以上的男性角色，唱和念白都用本嗓(又叫真声或大嗓)。照规矩，老生基本上都是戴三绺的黑胡子(术语叫作“黑三”)。另外还有灰色的三绺胡子，即花白的三绺胡子，专门名词叫“黪(音惨)三”，或“苍三”。还有白色的三绺胡子，叫作“白三”。还有一种胡子，不分绺，就是整片满口的胡子，术语叫作“满”，如黑满、白满、黪满。 照京剧原来的传统，不论是戴黑满的，或是戴黪三、黪满、白三、白满的，都不属于老生扮演的范围。只有戴黑三的，才能算是真正的老生。其他的角色都由“末”行或“外”行来应工。现在“末”“外”都合并到老生行当里，老生扮演角色的范围大为扩大，也就没有什么区别了。 老生一般分为文武两种，从表演的侧重点来划分，可以分成这么几种：唱工老生，做工老生，武老生。唱工老生也叫作安工老生，以唱为主。为什么叫安工老生呢?我想是因为这种老生既以唱为主，那么他的动作性就比较次要，动作幅度较小，态度比较安闲从容，唱的时候总是比较沉着安稳的，因此叫作安工老生。例如《二进宫》的杨波，《捉放曹》的陈官，《击鼓骂曹》的祢衡，《文昭关》和《鱼肠剑》的伍子胥，《洪羊洞》和《辕门斩子》的杨延昭，《空城计》、《雍凉关》、《战北原》、《脂粉计》、《七星灯》等剧的诸葛亮，《四郎探母》的杨延辉，《碰碑》的杨继业。《桑园寄子》的邓伯道，《让徐州》的陶谦，《逍遥津》的汉献帝等等，都属于唱工戏。还有一种介乎唱工戏和做工戏之间的以念白为主的戏，唱工老生和做工者生都可以兼演，仍如《十道本》的褚遂良，《夜审潘洪》的寇准，《审头刺汤》的陆炳，《审刺客》的闵觉等，都属于这一类。由于大段念白很难掌握，从表现技巧看，比起唱工和做工戏，难度大得多，所以这类戏现在很少演出了。做工老生又叫作哀派老生，是以表演为主的一种行当。衰派老生也有两种解释，一种是说，这类老生专门扮演年老体弱、戴白胡子的角色，所以叫作衰派。例如《清风亭》的张元秀，《扫松下书》的张广才，《三娘教子》的薛保，《九更天》的马义，《徐策跑城》的徐策等等，都屑于这一类。另一种解释说是因为以做工为主，一般都是表演精神上受了刺激，情绪紧张，神态粗犷，动作激烈的角色，这些角色的精神状态近乎颓唐衰朽，所以叫作衰派。例如《坐楼杀惜》的宋江，《打棍出箱》的范仲禹，《失印救火》的白槐，《春秋笔》的驿丞张恩，《战蒲关》的刘忠等等，都属于这一类。我认为衰派老生这个名词并不全面，还是说做工老生，特点就是侧重以表演为主，这样比较科学、严谨。唱工老生和做工老生都属于文老生的范畴。 武考生包括长靠和箭衣(俗称短打)两种。长靠老生又称靠把老生。“靠”是京剧的专门名词，就是古代武将所穿的铠甲。身穿铠甲，在京剧里叫作披靠或扎靠。“把”是“把子”的简称，就是兵器，俗称刀枪把子，也是京剧的专门名词。凡是身披铠甲，手持兵器，擅长武功的老生角色，都叫作靠把老生。例如《定军山》的黄忠，《阳平关》的黄忠，《失街亭》的王平，《战太平》的花云，《震潭州》、《八大锤》等剧中的
大学生简单的自我介绍范文推荐 如何做一个好的自我介绍也是大学生们在写简历时经常碰到的问题。今天就给大家分享几篇大学生简单的自我介绍优秀范文，大家一起随来看看吧。 我叫李添添，1992年6月1日出生，17岁，来自西安，我有着直爽的性格，但又不失稳重，不远千里来到怀化这座城市求学。 来到中专学习的事实和我的理想有很大的出入，难免有些郁闷，但在一段时间后，我认清了事实，很看计算机应用专业。"21世纪是电脑的世纪."这句话一点都不假，随着电脑的展，它为21世纪插上了腾飞的翅膀.后来在不断的培养兴趣过程中，我开始对电脑产生兴趣，今后的三年,我将在不断的学习进步中度过的。 “十年磨砺锋利出，宝剑只待君来识”。再苦再累，我都愿意一试，“吃得苦中苦，方为人上人”，在以后的学习生活中，我一定会是一位尽自己的努力、过一个充实而又意义的中专生活。 大学自我介绍篇2您好!我是XX大学XX学院XX专业毕业生，惠于学校浓厚的学习、创新氛围，熔融其中的我成为了一名复合型人才。大学的四年使我思想和知识,心理都得到了进一步的成长。 从入学以来，我立志要在大学四年里全面发展自己，从适应社会发展的角度提高个人素质。将来真正能在本职工作上做出成绩，为母校争光。在学习上我勤奋严谨，在掌握了本专业知识的基础上，不忘
拓展自己的知识面，对课外知识也有比较广泛的涉猎。我还很重视英语的学习，不断努力扩大词汇量，英语交际能力也有了长足的进步。 同时，为了全面提升个人素质，我积极参加各种活动，这些经历使我认识到团结合作的重要性，也学到了很多社交方面的知识，增加了阅历，相信这对我今后投身社会将起重要作用。现在虽存在着很多艰难和困苦,但我坚信大学生活给我的精神财富能够使我战胜它们。“长风破浪会有时，直挂云帆济沧海”，希望贵公司能给我一个发展的平台，我会好好珍惜它，并全力以赴，为实现自己的人生价值而奋斗，为贵公司的发展贡献力量。 大学自我介绍篇3我是一个性格稳重，心理素质较好的人。做事踏实认真，热情主动，吃苦耐劳，并且敢于承担责任。平时喜欢和他人沟通，善于与人相处，具有良好的团结合作精神。 四年来，我一直怀着对本专业的热爱，认真学习专业知识。学习了电路分析，微机原理，C/C++编程，数字/模拟电子技术，单片机，DSP，电路CAD等等一系列与电子相关的课程;出于对嵌入式开发的爱好,我自学了许多嵌入式方面的知识,比如ARM嵌入式系统，Linux 操作系统,Linux C编程,uc/GUI等。 参加了西南大学创新基金项目，并担任主要队员,培养了团队合作意识，学到了一定的开发经验，并了解到了很多先进技术。作为一名电子专业的大学应届毕业生，我所拥有的是年轻和知识。年轻虽然缺少经验，但是年轻也意味着热情和活力，我自信能凭自己的能力和学识在毕业以后的工作和生活中克服各种困难，不断实现自我的人
Sports Do you like sports? What’s your favorite sport? Maybe, you were asked many times for these two questions. Today I will tell you my answers. Firstly, I like sports. There are hundreds of sports throughout the world. Such as basketball, volleyball, swimming, running, and each of them has its special advantages. Sports benefit us in many respects. Sport is good for our health. It can make our body stronger. When taking part in sports, we get the chance to train almost all parts of our body. Sport is beneficial about relaxation. It can make us release our pressure. Sports can enrich our life and maintain our psychological health. It can let us get a healthy lifestyle. So I like sports. I enjoy participating in sports. I like keeping fit with sports and I like relaxing with sport. Secondly, my favorite sport is Yoga. Yoga starts from India. Nowadays, it’s very popular in the world. The early time that yoga appears can be traced back to B.C.. It’s the important mental creation of human beings. It can make people’s body more health through wriggle the body slowly. In addition, it can release people’s mind by listening the soft and beautiful music. So I like yoga. I feel that I not only gain a well-balanced life through yoga, but also get more chances to move closer to nature. I would like to take this opportunity to invite you to join me. Let’s doing yoga together, let’s doing sports, let’s get a healthy lifestyle.