Slide 1 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
GEOL4324: T & Th 2:00GEOL4324: T & Th 2:00--3:20pm3:20pmGeology of HydrocarbonsGeology of Hydrocarbons
Prof. HuaProf. Hua--wei Zhouwei ZhouRm211 of Science, Rm211 of Science, x21308x21308, , [email protected]@ttu.eduOffice Hours: T & Th 11amOffice Hours: T & Th 11am--noon, 3:30noon, 3:30--5pm, 5pm,
or by appointmentor by appointment
Slide 2 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Ch6: Reservoir continuity & characterization. Reserve calculations3/916
Ch6: Production methods; QZ4 (Ch6)3/1117
Ch6: Texture relating to porosity & perm. Effects of diagenesis on reservoir quality3/415
Ch6: The Reservoir: Porosity & permeability. Capillary Pressure. Grain texture3/214
Ch5: Petroleum system & basin modelling. QZ3 (Ch5)2/2513
Ch5: Formation of Kerogen. Petroleum migration2/2312
Ch5: Origin of petroleum. Modern surface organic processes2/1811
Midterm Exam One (Ch1-4)2/1610
Ch4: Subsurface fluid dynamics. Preview for Midterm One2/119
Ch4: Subsurface environment: waters. Subsurface temperatures & pressures2/98
Ch3: Subsurface geology. Remote sensing. QZ2 (Ch3)2/47
Ch3: Non-seismic & seismic methods. Borehole geophysics and 4D seismics.2/26
Ch3: Formation evaluation w/ various loggings. Intro to geophysical methods1/285
Ch3: Exploration: drilling & completion. Formation evaluation w/ e-logs1/264
Ch2: Crude oil chemistry & classification; QZ1 (Ch1-2)1/213
Ch2: Properties of various gases & gas hydrates1/192
Ch1: Historical review of petroleum exploration1/141
ContentDate#
Syllabus (adjustable)
Slide 3 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Final Exam5/629
Ch10: Assessment of basin & global reserves. Course review for Final Exam4/2728
QZ7 (Ch9); Ch10: Prospect appraisal. Geology, economics & probabilities4/2227
Ch9: Oil shales. Extraction of oil and oil shales. Shale gas & coal bed methane4/2026
Ch9: Plastic & solid hydrocarbons. Tar sands4/1525
Ch8: Distribution of hydrocarbons in basins; QZ6 (Ch8)4/1324
Ch8: Plate tectonics. Cratonic basins, troughs, rift basins & strike-slip basins4/823
Ch8: Formation & classification of sedimentary basins4/622
Midterm Exam Two (Ch5-7)4/121
Ch7: Review of Ch6 & Ch7. QZ5 (Ch7); Preview for Midterm Two3/3020
Ch7: Structural, diapiric, stratigraphic & hydrodynamic traps3/2519
Ch7: Traps: Nomenclature, petroleum distribution & classification. Seals and cap rocks3/2318
Spring Break3/18
Spring Break3/16
ContentDate#
Syllabus (adjustable)
Slide 4 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Ch9: Nonconventional Petroleum ResourcesCh9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbons
2.2. Tar sandsTar sands
3.3. Oil shalesOil shales
4.4. Shale gas & coalShale gas & coal--bed methanebed methane
Slide 5 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsClassificationClassification
Slide 6 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsOccurrenceOccurrenceTwo genetically distinct modes of occurrence:Two genetically distinct modes of occurrence: Inspissated & secondary depositsInspissated & secondary deposits
Inspissated depositsInspissated depositsThese are heavy hydrocarbons from which the light fraction has been removed. The situation can occur where an accumulation of liquid oil has been brought to the surface of the earth by a combination of migration, coupled with uplift and erosion. The oil will be subjected to flushing by meteoric water, leading to oxidation & bacteria degradation.
Surface occurrence of asphalt may be Surface occurrence of asphalt may be produced from seepages escaping from oil produced from seepages escaping from oil fields in the subsurface in various ways.fields in the subsurface in various ways.
Slide 7 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsOccurrenceOccurrenceTwo genetically distinct modes of occurrence:Two genetically distinct modes of occurrence: Inspissated & secondary depositsInspissated & secondary deposits
Inspissated depositsInspissated depositsIn the seepages on the shores of the Caspian Sea, such as Baku, not only oil but also mud and gas pour out on the earth’s surface. Spontaneous ignition frequently occurs, so that this region has been called the land of Eternal Fires.
Caspian SeaCaspian Sea
Slide 8 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsOccurrenceOccurrenceTwo genetically distinct modes of occurrence:Two genetically distinct modes of occurrence: Inspissated & secondary depositsInspissated & secondary deposits
Inspissated depositsInspissated depositsPetroleum seeps also occur offshore, in the Santa Barbara Channel of California, and off the coasts of Trinidad, Yucatan, and Ecuado.
Gas seeps, possibly of both shallow biogenic and thermal origin, are commonly recorded on sparker surveys around the world, and a major hazard to drilling and pipeline laying operations.
Slide 9 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsOccurrenceOccurrenceTwo genetically distinct modes of occurrence:Two genetically distinct modes of occurrence: Inspissated & secondary depositsInspissated & secondary deposits
Secondary depositsSecondary depositsThese are admixtures of sediment and heavy
degraded oil.
Extensive deposits of secondary petroleum are extremely rare, due to the tendency for oil to be degraded and oxidized in air & water.
Secondary deposits are occasionally found around oil seeps and mud volcanoes. They are important to help date the migration of petroleum.
Slide 10 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsCompositionComposition
Waxy solid hydrocarbons Waxy solid hydrocarbons are produced by the inspissation of paraffinic crude oils. They are generally plastic, waxy yellow to dark brown substances called ozokerite.
Chemically, the waxy solid hydrocarbons are paraffin derivatives, ranging from C22 to C29, with 84-86% carbon, 14-16% hydrogen, and traces of sulfur & nitrogen.
Asphaltic solid hydrocarbons Asphaltic solid hydrocarbons are produced by inspissation of naphthenic crude oil.
These compounds are similar to the waxy solid hydrocarbon in elemental chemistry, with 79.5-87.2% carbon, 8.9-13.2% hydrogen, <8% sulfur, and commonly traces of nitrogen, oxygen, and inorganic compounds.
Relative to that of the waxy solid hydrocarbons, the molecular composition of asphaltic solid hydrocarbons has much less paraffins & naphthenes, more aromatics, oxygen, nitrogen and sulfur.
As the asphalts are subject to inspissation, they grade through the asphaltites to asphaltic pyrobitumen.
Slide 11 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsCompositionCompositionAsphaltic solid hydrocarbons Asphaltic solid hydrocarbons
The asphaltites have a specific gravity of <1.2 and a melting point of 120-320oC. They are <60% soluble in naphtha and 60-90% soluble in carbon disulfide.
The asphaltic pyrobitumen are rubbery, brown substances with a specific gravity of <1.25. They do not melt, but swell and decompose on heating. They are insoluble in naphtha and only slightly soluble in carbon disulfide.
Slide 12 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbons
Composition & evolution of Composition & evolution of the solid hydrocarbons.the solid hydrocarbons.
Slide 13 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
1.1. Plastic & solid hydrocarbonsPlastic & solid hydrocarbonsSpace for self summarySpace for self summary
Slide 14 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsCompositionComposition
Heavy, viscous oil depositsoccur at/near the surface of the Earth in many parts of the world.
These deposits have API gravities in the range of 5-15o
and typically occur within highly porous sands, generally referred to as tar sands, or oil sands.
Canadian Tar Sands
Tar sands specimen close-up photo. From Asphalt Ridge near Vernal, Utah. Source: Argonne National Laboratory
Slide 15 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsCompositionComposition
Heavy, viscous oil depositsoccur at/near the surface of the Earth in many parts of the world.
These deposits have API gravities in the range of 5-15o
and typically occur within highly porous sands, generally referred to as tar sands, or oil sands.
Canadian Tar Sands
Slide 16 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sands
Vast reserves of Vast reserves of hydrocarbons are hydrocarbons are contained in tar sands!contained in tar sands!
Notice error in the Notice error in the amount of reserves of amount of reserves of this table!this table!
CompositionComposition
Slide 17 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsCompositionCompositionIn terms of physical and chemical properties, the change from normal crude oil, via heavy oil, into tar is a gradual one.
Physically, the oils become heavier & more viscous. Chemically, the oils tends to contain more inorganic impurities and to be more sulfurous and aromatic.
Comparing the composition of a number of tar sands with light crudes in Fig. 9.6, tar sands tend to be enriched in resins & asphaltenes, and impoverished in saturated hydrocarbons. There is not as much difference in their aromatic content.
Slide 18 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsCompositionComposition
Two possible explanations have been proposed to account for the differences between normal light crudes & tar sands.
Firstly, the heavy oils of tar sands may be young and have yet to mature to light oil.
Alternatively, the heavy oils of tar sands may have been produced by the degradation of mature light oil.
Degradation occurs by both organic & inorganic processes. Nonetheless, the origin of heavy oils is controversial.
Slide 19 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsGeologic settingGeologic setting
Let consider the geologic setting of tar sands.
The majority occur where major basins transgress over Precambrian shields.
They occur in fluvial or deltaic sands, rather than marine sands or carbonates.
On a smaller scale tar sands occur in two ways:
in situ in erosionally breached traps (e.g., Bemolanga oil sands of Malagasy);
migrated from deep traps into surface seepages (e.g., La Brea deposits of Trinidad & Athabasca tar sands of Canada).
Slide 20 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsGeologic settingGeologic settingThe The BemolangaBemolanga tar sands of Malagasytar sands of MalagasyOccur in the Isalo Group (Triassic) of the Karroo system, covering an area of ~388 km2 with an overburden of >100 m in thickness.
The tar sands lie within a complex faulted anticline, where the cap rock of the Bemolanga clay has been removed by recent erosion.
The sands are cross-bedded, coarse, and fluvial. Local dykes of Cretaceous age have locally metamorphosed the tar. The underlying Sakamena shale is believed as the source for the oil.
The average pay is ~30 m thick, and reserves is ~ 1.75 b. bbl.
Slide 21 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsGeologic settingGeologic settingThe La Brea tar sands of TrinidadThe La Brea tar sands of Trinidad
Oil of the 126-acre La Brea asphalt lake has emigrated from an accumulation in a Cretaceous anticline up through an imperfect seal to reach the surface.
The tar sands lie in a depression within Miocene sands; it is still actively flowing, as shown by modern mud volcano activity.The estimated reserves is 60 million barrels.
Slide 22 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsGeologic settingGeologic settingThe La Brea tar sands of TrinidadThe La Brea tar sands of Trinidad
Oil of the 126Oil of the 126--acre La Brea asphalt lake has emigrated acre La Brea asphalt lake has emigrated from an accumulation in a Cretaceous anticline up from an accumulation in a Cretaceous anticline up through an imperfect seal to reach the surface.through an imperfect seal to reach the surface.
The tar sands lie in a depression within Miocene sands; The tar sands lie in a depression within Miocene sands; it is still actively flowing, as shown by modern mud it is still actively flowing, as shown by modern mud volcano activity.volcano activity.The estimated reserves is 60 million barrels.The estimated reserves is 60 million barrels.
Slide 23 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsGeologic settingGeologic settingThe Athabasca tar sands of CanadaThe Athabasca tar sands of CanadaThe heavy oil occur in fluviodeltaic sands of the Manville Group (Lower Cretaceous), which where derived mainly from the west, but with local deltaic spreads of sand from the east. Subsequently, the strata were tilted regionally to the west and very gently folded.
Normal light oils (35-40o API) were generated in the western part of the Alberta basin, but tar sands are now encountered in stratigraphic pinchout and fold-pinchout combination traps along the eastern margin.
Slide 24 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Schematic section showing oil trapped in sands and carbonates (from Proctor et al., 1983).
2.2. Tar sandsTar sandsGeologic settingGeologic settingThe Athabasca tar sands of CanadaThe Athabasca tar sands of CanadaThe heavy oil occur in fluviodeltaic sands of the Manville Group (Lower Cretaceous), which where derived mainly from the west, but with local deltaic spreads of sand from the east. Subsequently, the strata were tilted regionally to the west and very gently folded.
Normal light oils (35-40o API) were generated in the western part of the Alberta basin, but tar sands are now encountered in stratigraphic pinchout and fold-pinchout combination traps along the eastern margin.
Index map of oil sands, carbonate triangle, heavy oil, and deep-basin gas (from Proctor et al., 1983).
Slide 25 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsOrigin of tar sandsOrigin of tar sands
The origin of tar sands is controversial. The debate revolves around whether the oil is immature, or mature and subsequently degraded.
An early idea stated that the oil was formed in the sands that now contain them. The reasons included the flat-lying nature of the sediments and the apparent absence of normal crudes in the area.
Another idea is that the heavy oils are mature oils that have undergone degradation by meteoric flushing. The reason included cases that oils can be traced gradationally up the basin margin from deep light oil pools. The gradational lightening of the oil basinward is accompanied by increased formation water salinities.
One more idea is the immature origin. The evidence includes their higher porphyrin content, the absence of insoluble benzene matter, their molecular weight distribution, and their nickel:vanadium ratio. Also the chemical composition of the oil shows that it has not undergone significant thermal maturation.
Slide 26 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsExtraction of oil from tar sandsExtraction of oil from tar sandsDuring the last half century, the low cost of conventional light crude inhibited interest in heavy oil production, and little research was put into the technology of extracting the oil from tar sands.
The situation is rapidly changing due to the huge price rises of crude oil and the ultimate global shortage of conventional oil.
The methods extracting heavy oil include:
Surface mining
Tar Sands Open Pit Mining, Alberta, Canada
Slide 27 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsExtraction of oil from tar sandsExtraction of oil from tar sandsDuring the last half century, the low cost of conventional light crude inhibited interest in heavy oil production, and little research was put into the technology of extracting the oil from tar sands.
The situation is rapidly changing due to the huge price rises of crude oil and the ultimate global shortage of conventional oil.
The methods extracting heavy oil include:
Surface mining
Tar Sands Extraction Separation Cell, Alberta, Canada
Slide 28 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsExtraction of oil from tar sandsExtraction of oil from tar sandsDuring the last half century, the low cost of conventional light crude inhibited interest in heavy oil production, and little research was put into the technology of extracting the oil from tar sands.
The situation is rapidly changing due to the huge price rises of crude oil and the ultimate global shortage of conventional oil.
The methods extracting heavy oil include:
Surface miningSubsurface extraction
Slide 29 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsExtraction of oil from tar sandsExtraction of oil from tar sandsProblems of strip mining tar sands include:
The economic thickness of overburden that can be tolerated;The degree of environmental opposition of the native population
Once the tar sands have been quarried, the extraction consists of disaggregation of the sand and separation of the oil by hot water and/or stem.
Where the overburden is too thick for open-cast mining, in situ extraction methods are developed:
Injection of solvent to dissolve the oilSeeking to reduce the oil’s viscosity be heating
The technology of extracting oil from tar sands still has long way to go, and is the subject of current research.
Slide 30 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
2.2. Tar sandsTar sandsSpace for self summarySpace for self summary
Slide 31 GEOL4324: Geology of Hydrocarbons
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3.3. Oil shalesOil shalesDefinitionDefinition
Oil shale is a fine-grained sedimentary rock that yields oil on heating.
Fractured oil shale specimen showing weathered and unweathered surfaces. UintaBasin, Utah. Source: Argonne National Laboratory
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Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesDefinitionDefinition
Oil shale is a fine-grained sedimentary rock that yields oil on heating.
It differs from tar sand in more than grain size. In tar sands the oil is free and occurs within the pores. In oil shales, however, oil seldom occurs free, but is contained within the complex structure of kerogen, from which it may be distilled.
Craig (1915) wrote: “To make the matter clear, the relation of malt & hops to beer is somewhat similar to that of oil shales, coal &lignite to petroleum. The malt & hops do not contain beer, but it can be made from them by causing certain chemical changes. Oil can be made from oil shales, coal & lignite, but only by destroying them.”
Combustion of oil shale
Oil shales are widely distributed around the globe and may contain locked within them more energy than in all the presently discovered conventional oil reserves. The world’s oil shales may contain ~30 trillion bbl of oil, only about 2% of which is accessible using present-day technology (Yen & Chilingarian, 1976).
Slide 33 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesChemical compositionChemical composition
Most oil shales are essentially claystones & siltstones, but bituminous marls and lime mudstones are also known. The basic constituents of oil shales may be grouped as follows:
1. Inorganic components (<90%)1. Inorganic components (<90%)QuartzFeldsparMica
Detrital Accessory mineralsCarbonatesClays AuthigenicPyrite
2. Organic components (102. Organic components (10--27%)27%)Bitumens (hydrocarbons soluble in CS2) around 2%Kerogens (insoluble in CS2) around 8%
Slide 34 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesChemical compositionChemical composition
The exact amount of organic matter needed before a shale can be classified as an oil shale is arbitrary. A cut off value of 10% has been cited. With increasing organic content to more than 27%, oil shales grade into the cannel coals.
The inorganic component of oil shales differs little from that of conventional shales. Detrital grains include quartz, feldspar, mica. Large amount of clay are present, both detrital floccules & authigenic crystals. Various carbonate minerals are present. Authigenic pyrite also presents, carrying sulfur which causes a major problem of oil shale refining.
Kerogen is the important constituent of oil shale. An oil definition of kerogen by Stewart (1912) is “carbonaceous matter in shale which gives rise to crude oil on distillation”. Currently, kerogen is defined and distinguished from bitumen by its insolubility in carbon disulfide.
The organic precursor of the kerogens in oil shales are hard to determine, though thesource of the organic matter of most oil shales is generally believed be admixtures of algal & terrestrial humic materials. Two rare types of oil shale whose biological origin is well know are Torbanite & Tasmanite. Torbanite, also termed bog head or cannel coal, are made of algal matter. Tasmanite occurs in marine deposits.
Slide 35 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesDistributionDistributionThe occurrence & distribution of oil shales are widespread in place & time.
There appear to be few genuine Precambrian oil shales.
In the early Paleozoic, however, siliceous oil shales were deposited on marine shelves throughout the Northern Hemisphere.
In the late Paleozoic, oil shales were deposited on marine shelves in central European Russia and in the central & eastern US and Canada.
At the Devonian-Carboniferous boundary oil-shale-forming environments appear to have changed significantly. Paralic deltaic-lacustraine oil shales are characteristic of Carboniferous deposits worldwide.
During the Permian period both paralic & marine shelf oil shales formed. The Iratioil shale of this age covers several hundred thousand km2 in eastern South America and South Africa.
Slide 36 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesDistributionDistributionDuring the Permian period both paralic & marine shelf oil shales formed. The Irati
oil shale of this age covers several hundred thousand km2 in eastern South America and South Africa.
Slide 37 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesDistributionDistributionIn late Mesozoic time many oil shales formed in marine, deltaic, and lacustrine environments. In NW Europe, a major phase of oil shale and organic-rich shale deposition began in N. Germany in the Liassic and moved diachronically northward up the North Sea into the East Greenland Mesozoic basin. Analogous marine platform oil shales occur in Alaska, Saskatchewan, Manitoba, and in Nigeria.
The Cenozoic Era saw another return to lacustrine oil shale deposition, although marine oil shales do occur. The best example is the Eocene Green River Formation of Colorado, Utah & Wyoming.
Slide 38 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesDistributionDistribution
Three major depositional environments are favourable for oil shale generation: Lakes, fluvially dominated deltas, & certain marine shelves.
Torbanites & oil shales of mixed humic and nonmarine algal origin are characteristic of lacustrine & deltaic shales.
Shallow marine oil shales, however, are commonly of mixed humic and marine algal composition, including the rarer algally dominated tasmanite variety.
Oil shales of both lacustrine & marine types are occasionally associated with autochthonous chemical deposits.
The world’s reserves of shale oil are estimated to be on the order of 30 trillion bbl, and the US alone contains >0.7 trillion bbl (Yen & Chilingarian, 1976).
Slide 39 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesExtraction of oil from oil shaleExtraction of oil from oil shale
Production of oil shale (megatons) in Estonia, Russia (Leningrad & Kashpirdeposits), UK (Scotland, Lothians), Brazil (IratíFormation), China (Maoming & Fushun deposits), and Germany (Dotternhausen) from 1880 to 2000.
The commercial extraction of oil from shale was begun by James Young in Scotland in 1862. During the next century, oil shale extraction was carried out in England, France, Spain, Sweden, Australia, & South Africa. The industry has since collapsed in these countries.
The Figure below shows the peak of oil shale production around 1980. The main producing countries include Estonia, China, Russia & Brazil. Two reasonsTwo reasons for the rise and fall of the oil shale extraction are economics & technologyeconomics & technology. So we expend the trend to pick up again.
Slide 40 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesExtraction of oil from oil shaleExtraction of oil from oil shaleLike the tar sands, there are two basic methods of winning oil from shale:
(1) By retorting shale quarried at the surface: Shale is crushed on the open-cast quarry, then placed in a retort and heated. Several sources of heat can be used, but the most efficient is by the combustion of gas previously generated from the shale. As the shale is heated in the range of 425-475oC, oil and gas are driven off by the pyrolysis of the kerogen. Spent shale collects at the bottom of the retort. The oil is refined, the gas reinjected, and the ash cooled and disposed of, it is hoped at least partly back in the hole whence it came. This method has considerable environmental objections.
(2) By underground in situ extraction: Two requirements are that an effective method of heating the shale is available and the rock must be rendered permeable. Several example case were described in the text.
The day may come soon when the rising cost of conventional crudeThe day may come soon when the rising cost of conventional crude oil intersects oil intersects the coast of shale oil.the coast of shale oil.
Slide 41 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
3.3. Oil shalesOil shalesSpace for self summarySpace for self summary
Slide 42 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneShale gasShale gasShale gas is natural gas produced from shale. Because shales ordinarily have insufficient permeability to allow significant fluid flow to a well bore, most shales arenot sources of natural gas. Shale gas is one of a number of “unconventional”sources of natural gas, usually from fractured shale reservoirs.
In the US petroleum gas was first produced from fractured shale reservoir in 1821. Extensive shale gas production was established in the Appalachian basin, and there are many other potential areas for shale gas production throughout the US.
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Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneShale gasShale gas
Shale gas is seldom trapped in well-defined fields; instead it occurs in siltstone bands and irregular fracture systems. The gas is of high calorific value, and commonly wet, with >10% ethane. After an initial high pressure “blow” well head pressures stabilize at 300-500 psi with flow rates of 50-100 thousand cubic feet of gas per day. Depletion rates however are of the order of 10% per year, with individual wells producing for 40-50 years. Wells are seldom >700 m deep, and thus cheap to drill.
Shale gas exploitation is not profitable for major international oil companies, because the reserves are too small and the payout time too long. Shale gas is economically viable in the US because land ownership includes the mineral rights of a property, and the “cottage industry’ scale of many small oil companies permits operations with small profit margins.
Slide 44 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneShale gasShale gas
It is now known that the regional distribution of shale gas is controlled by the quantity, quality, and level of the maturation of organic matter in the shale formations. Local concentrations of shale gas occur either in siltstone strata or in fracture systems.
Siltstone beds commonly occur in the syndepositional lows that are carefully avoided in conventional petroleum exploration.
Slide 45 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneShale gasShale gasUK also has good potential for shale gas. This figure shows the main Carboniferous features of Britain. During the early Carboniferous, N Britain consisted of a serious of stable platforms and subsiding basins. Limestones were deposited on the former and shales in the latter. The shales are rich in organic matter, ranging from the Tasmanites-bearing oil shales of the Midland Valley of Scotland to the more humic shales of N. England.
Slide 46 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneShale gasShale gasRemote sensing and seismic surveys may help located fracture systems, which may be best developed where strata are stretched over the crests of anticlines, or along regional fault and basin hinge-line trends. Specific methods of seismic survey and processing have now been developed to locate low-velocity gas-charged shale zones.
Shale gas is found by air drilling. Conventional drilling with a mud-filled hole will seldom locate shale gas. The weight of the mud forces the gas away from the well bore. Such gas as may escape into the drilling mud is recorded as “background gas”, with little thought that it may be commercial.
Transportation of shale gas far from the well head is seldom feasible. Because of the low pressure, the gas must be pressurized for it to flow along a pipeline. This additional cost generally destroys the profitability. Hence, shale gas is an eminently suitable energy source when located adjacent to a town or users.
Shale gas production has a negligible environmental impact. Once the well is drilled there is no derrick. There is no need for well-head pumps, no flaring, and no long-distance pipelines. The production is modest, but reliable, quiet, and long term.
Slide 47 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneCoalCoal--bed methanebed methaneCoal-bed methane (CBM), also called coal-bed gas, is a form of natural gas extracted from coal beds. The methane is adsorbed into the solid matrix of the coal. It is 'sweet' because of its lack of hydrogen sulfide. A truckA truck--mounted drill rig used by gas mounted drill rig used by gas
developers for shallow drilling of developers for shallow drilling of coalcoal--beds in the Powder River Basin. beds in the Powder River Basin.
Traditionally CBM is a major safety hazard to coal miners. Extensive ventilation systems are required to extract methane from working coal mines.
CBM is distinct from a typical sandstone or other conventional gas reservoir, as the methane is stored within the coal by a process called adsorption. The methane is in a near-liquid state, lining the inside of pores within the coal matrix. The open fractures in the coal can also contain free gas or can be saturated with water.
Slide 48 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneCoalCoal--bed methanebed methane
Unlike shale gas, most coals only produce dry gas, methane. The goal-bed gas thus have a lower calorific value than shale gas. Coal beds normally have more fractures and higher permeability than shales.
The parameters that control the methane-generating potential of a coal include: rank, ash content, maceral (component of coal) type, matrix porosity, fracture porosity, pressure, and water content.
CBM production(from EPA)
Slide 49 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
4.4. Shale gas & coalShale gas & coal--bed methanebed methaneCoalCoal--bed methanebed methane
A CBM treatment ponds on the Black Warrior River. (Jefferson County, Alabama)
CBM well in the foreground, Miller Steam Plant in the background. (Jefferson County, Alabama)
Nonconventional petroleum resources Nonconventional petroleum resources will play a much big role in the future!will play a much big role in the future!
Slide 50 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Production of oil and gas in reservoirs with low primary permeability (e.g. carbonate and shale reservoirs) depend heavily on natural or induced fractures
Reservoir fracture & stress may be characterized based on seismic data (velocity anisotropy and micro-seismicity), together with geologic and production info
Extra information:Extra information:Reservoir fracture & stress characterizationReservoir fracture & stress characterization
Slide 51 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Sections & volumes of seismic images
Seismic-well tie
Seismic attributes
Seismic anisotropy
Monitoring of micro-seismicity
o First motion strain axes of micro-seismicity?
o ‘Day light’ seismic imaging?
Reservoir fracture & stress characterizationReservoir fracture & stress characterizationSeismologic Contributions:Seismologic Contributions:
Slide 52 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Reservoir fracture & stress characterizationReservoir fracture & stress characterization
Slide 53 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Generalized stratigraphic column and detail of Mississipian strata
Reservoir fracture & stress characterizationReservoir fracture & stress characterization
(Pollastro, 2003)
Slide 54 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Isochron map of the reservoir (4ms intervals). The reservoir is slightly thicker towards the NE; the main fault does not define areas of different thickness, showing that the vertical displacement happened after reservoir formation
(Simon, 2005)
Reservoir fracture & stress characterizationReservoir fracture & stress characterization
Slide 55 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Time contours of the top of the reservoir (4ms contour interval) and azimuthal interval velocity icons. The azimuthal change in the velocity field around the fault is consistent with right-lateral strike-slip motion.
(Simon, 2005)
Slide 56 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Slide 57 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
(Simon, 2005) 0300
600
900
1200
15001800
2100
2400
2700
3000
3300
36003900
Fast Int. Veloc.Mid-Reservoir
[ft/s]
13000 19000
(FA
S T-S
LOW
)IN
TER
VAL
VELC
ITY
[FT/
S]
Azimuth Arrows:Azim. Fast Int. Veloc.
Mid-Reservoir
FLAT AREA
LARGE K+CONVEX
SMALL K-CONCAVE
Km
axBO
TR
E FL E
CT O
R
ColorColor--filled contours of filled contours of bottombottomreflector reflector KKmaxmax, and arrows of interval , and arrows of interval velocity attributes (azimuth & size is velocity attributes (azimuth & size is that of that of VfVf, color show , color show VfVf--Vs).Vs).
10K FT0
Slide 58 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Slide 59 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Slide 60 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Definition: Capturing an interpreter’s thoughts with a computer algorithm。
Seismic attributes
Slide 61 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Fault detectionFault detection (Gulf of Mexico, USA)(Gulf of Mexico, USA)
Salt
Salt
Slide 62 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
kpos < 0 kpos = 0 kpos > 0
kneg = 0
kneg > 0
kneg < 0bowl
plane
synform
saddle
antiform
dome(Bergbauer et al., 2003)
Geometrical Attributes:
Curvature of folded surfaces
Slide 63 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Line 1
Line 3
Line 4
Line 5
Line 6
Line 2
Coherence AttributesCoherence Attributes
(Chopra and Marfurt, 2007b)
Slide 64 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Line 1
Line 3
Line 4
Line 5
Line 6
Line 2
Most-Positive Curvature Strat Slices
(Chopra and Marfurt, 2007b)
PositivePositive curvaturecurvature
Slide 65 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Line 1
Line 3
Line 4
Line 5
Line 6
Line 2
Most-Negative Curvature Strat Slices
(Chopra and Marfurt, 2007b)
NegativeNegative curvaturecurvature
Slide 66 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
B B′5 km
Caddo
Ellenburger
Basement?
pos
Amp
0
neg
Tim
e (s
)
0.75
1.00
1.25
0.50
1.50
1.75
0.25
A seismic section of the A seismic section of the FortworthFortworth BasinBasin
Slide 67 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
0.80
Time (s)
0.75
0.70
0.85
B
B′5 kmTime/structure of Caddo horizonCaddoCaddo group group horizon structurehorizon structure
Slide 68 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
0.06
Dip (s/km)
0.00
B
B′5 kmDip magnitude from picked horizonCaddoCaddo group group dipping attributesdipping attributes
Slide 69 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
B
B′NS dip from picked horizon
-0.06
Dip (s/km)
0.00
+0.06
CaddoCaddo group group NS dip attributeNS dip attribute
Slide 70 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
B
B′NS dip from multi-window scan
-2
Dip (deg)
0
+2
CaddoCaddo groupgroup windowed NS dip attributewindowed NS dip attribute
Slide 71 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
B
B′EW dip from picked horizon
-0.06
Dip (s/km)
0.00
+0.06
CaddoCaddo group group EW dip attributeEW dip attribute
Slide 72 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
B
B′
-2
Dip (deg)
0
+2
CaddoCaddo groupgroup EW dip from multiEW dip from multi--window scanwindow scan
Slide 73 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
-2
Dip (deg)
0
+2
ϕ=00ϕ=300ϕ=600ϕ=900ϕ=1200ϕ=1500
Time slices through apparent dip (t=0.8s)CaddoCaddo groupgroup
Slide 74 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
ϕ=00ϕ=300ϕ=600ϕ=900ϕ=1200ϕ=1500
Time slices through apparent dip (t=1.2s)
-2
Dip (deg)
0
+2
Caddo groupCaddo group
Slide 75 GEOL4324: Geology of Hydrocarbons
Ch9: Nonconventional Petroleum Resources
Thank You Thank You !!
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