PowerPoint PresentationThe Rocks
ROCK (BATUAN)
A naturally formed aggregate of usually inorganic materials from within the Earth. Terbentuk secara alamiah yang umumnya material inorganic dari bumi.
IGNEOUS ROCK (batuan beku)
A rock made from molten (melted) or partly molten material that has cooled and solidified. Yang berasala dari material larva yang telah dingin dan membeku.
METAMORF ROCK (batuan Metamorf)
A rock that has undergone chemical or structural changes. Heat, pressure, or a chemical reaction may cause such changes. Yaitu batuan beku yang telah terjadi perubahan struktur yang disebabkan oleh panas, tekanan dan proses rekasi kimia.
SEDIMENTARY ROCK (Batuan Sediment)
A rock made from the consolidation of solid fragments, as of other rocks or organic remains, or by precipitation of minerals from solution. Yaitu batuan yang terbentuk akibat gabungan dari material padat, batuan lainnya dan sisa organic yang kemudian terendapkan.
Basic Petroleum Geology
A sedimentary rock has a long history and has been
subjected to modification by various processes. Batuan sediment mengalami proses yang panjang dan mengalami proses yang berfariasi sehingga bentuknya termodefikasi.
erosion
Basic Petroleum Geology
The first process, WEATHERING, produces the materials that a sedimentary rock is composed of by mechanical (freezing) and chemical (dissolution of minerals, formation of new minerals [clays]) interaction between atmosphere, hydrosphere and earth surface rocks
The second process, TRANSPORT, moves these materials to their final destination. Rivers are the main transporting agent of material to the oceans. During transport the sediment particles will be sorted according to size and density and will be rounded by abrasion. Material that has been dissolved during weathering will be carried away in solution. Winds may also play a role. The sorting during transport is important because it is the reason that we have distinct clastic rock types (conglomerates, sandstones, shales)
The third process, DEPOSITION, of a sediment, occurs at a site with a specific combination of physical, chemical and biological conditions, the sedimentary environment
Finally, after the sediment has come to rest, COMPACTION and CEMENTATION of the sediment occur and a sedimentary rock is formed. Compaction is effected by the burden of younger sediment that gets piled on top of older sediments (rearrangement of particles, packing, dewatering). Minerals precipitated from the pore waters in these sediments cement together adjacent sediment grains. Thus, a coherent solid rock is formed.
Source :http://www.indiana.edu/~geol105/1425chap5.htm
Basic Petroleum Geology
severely deformed, the oldest
successively younger ones above.
Of the relative ages of all strata and
Their contained fossils.
Basic Petroleum Geology
Steno’s law
because sedimentary particles settle
of gravity, stratification was originally
horizontal and when steeply inclined
must have suffered subsequent disturbance
Source: http://www.bhc.edu/academics/science/harwoodr/GEOL101/STUDY/Images/Beach01.jpg
Modern depositional system
Ancient deposit
Natural laws do not change—however, rates and intensity of processes may.
Basic Petroleum Geology
Basic Petroleum Geology
Structural Geology is study the architecture of rock
Structural Geology is concerned primarily with the geometry of the rock, whereas tectonics deals with forces and movement
(Billings)
4 type of structures,
Ada 4 type struktur pergerakan dan gaya yang terjadi pada batuan
1. Fold (anticline and syncline)
2. Joint or Fracture
Lithosphere
Astenosphere
Gunung api meletus mengeluarkan magma panas dari dalam bumi. Magma yang sampai ke permukaan bumi disebut lava. Magma dan lava yang membeku akan terbentuk menjadi batuan beku. Batuan beku yang berada disekitar gunung api akan mengalami erosi dan transportasi, dan akan diendapan disuatu tempat sehingga terbentuk batuan sedimen. Batuan beku dan batuan sedimen bila terkena tekanan dan panas yang tinggi akan berubah menjadi batuan metamorf. Dengan pemanasan yang semakin tinggi dari persinggungan dengan magma didalam bumi, batuan akan meleleh kembali membentuk magma dan kembali keluar sebagai lava pada saat gunung api meletus.
Basic Petroleum Geology
Plate Tectonic
Gunung api meletus mengeluarkan magma panas dari dalam bumi. Magma yang sampai ke permukaan bumi disebut lava. Magma dan lava yang membeku akan terbentuk menjadi batuan beku. Batuan beku yang berada disekitar gunung api akan mengalami erosi dan transportasi, dan akan diendapan disuatu tempat sehingga terbentuk batuan sedimen. Batuan beku dan batuan sedimen bila terkena tekanan dan panas yang tinggi akan berubah menjadi batuan metamorf. Dengan pemanasan yang semakin tinggi dari persinggungan dengan magma didalam bumi, batuan akan meleleh kembali membentuk magma dan kembali keluar sebagai lava pada saat gunung api meletus.
Basic Petroleum Geology
Basic Petroleum Geology
What is Petroleum System ?
A natural system that encompasses a pod of active source rock and all related oil and gas and which includes all the geologic elements and processes that are essential if a hydrocarbon accumulation is to exist (Magoon and Dow, 1994)
Important Factors in Petroleum System. Faktor penting dalam sistem Perminyakan:
Mature SOURCE ROCK (Batuan Induk)
MIGRATION path connecting source rock to reservoir rock (Pergerakan dari batuan induk ke batuan reservoir)
A RESERVOIR ROCK that is both porous and permeable
A TRAP And impermeable SEAL
- There must be a rock containing original organic matter
- The source rock must be buried deeply (batuan source rock harus terpendam dalam)
- Even where the organic matter can become mature, not all of it becomes petroleum (tidak semua bahan organik bisa menjadi minyak)
- Only a small part is able to undergo migration out of the source bed (hanya sebagian kecil yang bisa bermigrasi ke lapisan induk (source))
Basic Petroleum Geology
IPIMS
IPIMS
Theories of Inorganic Origin
Exclusively inorganic theories of the hydrocarbon origin are maintained only by a few Russian scientists
- Condensed acetylene (C2H2) to form heavier hydrocarbon
- Bitumen in igneous and volcanic rocks
- Hydrocarbon smog in atmosphere
- Chemical petroleum composition allies it with organic materials
- Associated oil and gas in marine rich fossil sediment rock
- Analogy to coal as it is known to originate in terrestrial plant
Basic Petroleum Geology
How the way people simply explain Organic Origin Theory :
Millions of years ago, tiny animals and plants lived in the sea. When they died, they sank to the bottom and were buried in the sand. Rivers carried more bits of rock and sand into the sea. The layers of rock and sand were pressed down so tightly that they formed sedimentary rock. The animals and plants decayed in the rocks and changed into oil and gas.
Jacqueline Dineen, 1995
Basic Petroleum Geology
Source Rock
SOURCE ROCK are any rocks in which sufficient organic matter to form petroleum has been accumulated, preserved, and thermally matured
Organic particles are usually fine-grained, and will settle out most easily in quiet-water environments
One of the most important factors in determining whether an organic-rich rock will become a source rock is its thermal maturity
IPIMS
Source Rock
In the early stages of this alteration, or diagenesis, an intermediate form of organic matter, called kerogen, is formed
Different kinds and proportions of biological molecules form different types of kerogen, chemical compositions and types/amounts of petroleum
IPIMS
- Secondary : Migrate through reservoir for entrapment
Hydrocarbon Migration
Seals
Traps must be sealed by impermeable barriers in order to stop the continued upward migration of petroleum. In the case of anticlines only a vertical seal, or cap-rock, is required; but faults and stratigraphic traps must be sealed both vertically and laterally.
Shale is the dominant cap-rock of worldwide reserves and is overwhelmingly the seal in basins rich in terrigenous sediments, where sandstones are the dominant reservoir rock.
Basic Petroleum Geology
Trapping Mechanisms
Traps may contain oil, natural gas, or a combination of both, with gas trapped at the highest level
Basic Petroleum Geology
Trapping Mechanisms
Many stratigraphic traps are limited only by the quantity of petroleum they contain. Others, however, may be limited by the size and shape of the reservoir and by lateral lithologic changes.
Basic Petroleum Geology
A porous and permeable rock containing oil, gas or water
Most of the prolific oil production and indeed most of the giant oilfields are in sandstones. Sandstones generally exhibit high primary permeabilities as well as secondary permeability characteristics. For example, most of the oil and gas produced in Russia is from clastic reservoir rocks. Much of the production from the USA has also been from clastic reservoir rocks. All or almost all Centra Sumatra Basin reservoirs are sandstones.
But there are some notable exceptions. For example, the Permian Basin of the southwestern U.S.A., Jatibarang Fm. In West Java are Carbonate (limestone) reservoirs. Very minor are volcanic and fractured igneous reservoirs.
Reservoir Rocks
Basic Petroleum Geology
PERMEABILITY is a measure of a rock's ability to conduct fluids
The unit of permeability is the Darcy. A rock having a permeability of one darcy allows a fluid of one centipoise viscosity to flow at a velocity of one centimeter per second for a pressure drop of one atmosphere per centimeter
q = rate of flow
A = cross-sectional area of sample
m = viscosity of fluid
q = k(P1-P2)A / (mL)
Basic Petroleum Geology
POROSITY is the first of two essential requirements for a rock to act as a hydrocarbon reservoir
It is simply a measurement of the pore or void spaces in a rock
volume of void
Porosity (%) = ------------------------- x 100
Porosity is often represented by the Greek letter phi (f)
Interconnected
Isolated
Porosity
IPIMS
Basic Petroleum Geology
POROSITY is affected by rock FABRIC. Fabric refers to the way in which the grains in the sediment are actually arranged:
The way in which the grains are packed
The way in which the various particles are actually oriented
Rock Fabric
SECONDARY POROSITY is porosity formed within a reservoir after deposition.
Fenestral
Intercrystalline
Basic Petroleum Geology
POROSITY is generally unaffected by grain size but PERMEABILITY increases with increasing grain size and better sort
Grain size
1.2
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