Term
| Requirements for Commercial Petroluem Accumulations |
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Definition
1. A source, material from which oil is formed
2. Porous and permeable rock for migration and accumuation
3. A trap, something that restricts the flow of oil or gas
4. Petroleum must be recoverable |
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Term
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Definition
Petra- meaning rock
Oleum- meaning oil |
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Term
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Definition
liquid- crude oil
gaseous- natural gas |
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Term
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Definition
1. inorganic theories- combination of chemical reactions occur naturally to form crude oil or natural gas
2. organic theories- fossil fuels were formed from the remains of plants and animals that lived long ago |
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Term
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Definition
1.bacterial action
2. Heat
3. Pressure
4. Chemical reactions
5. radioactive bombardment |
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Term
| Eras and % of giant oil and gas reservoirs |
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Definition
| Cenozoic-40% Mesozoic-50% Paleozoic-10% |
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Term
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Definition
1. Compactions of sediments as depth of burial increase
2. Diastrophism: crustal movement causing pressure differentals
3. Capillary forces casuing oil to be expelled from fine pores by entry of water
4. Gravity (buoyancy due to density difference) |
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Term
| Primary and secondary migrations |
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Definition
Primary- movement of oil from source rock to carrier rock
Secondary- oil or gas moves from carrier beds to traps |
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Term
| Is oil migration efficient? |
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Definition
| no, 1-10% of hydrocarbons end up in reservoirs from source rocks |
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Term
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Definition
| natural gas trapped within shale formations, fracturing is required to extract shale gas |
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Term
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Definition
| organic-rich fine-grained sedimentary rock (Marlstone) containg Kerogen (heat and pressure hasnt transformed kerogen into petroleum) |
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Term
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Definition
| heating shale oil to produce a vapor than can be made into combustible oil-shale gas |
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Term
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Definition
1. structural traps
folds
compressional- tectonic processes
compactional- deopositonal/tectonic
Faults
2.Stratigraphic traps- deopsitional morphology
3. Hydrodynamics- water flow
4. Combinations traps- combo of 2 or more |
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Term
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Definition
| due to post-depositional processes- folding and faulting |
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Term
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Definition
| due to change in lithology (by deposition or diagensis) |
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Term
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Definition
| downward movement of water prevents the upward flow of oil |
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Term
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Definition
| upward escape of oil has been stopped by an impermeable material laid down on the weathered surface of the lower bed |
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Term
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Definition
| upward movement of less dense sediments, oil found around salt plugs (anticlines) |
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Term
| % of giant reservoir traps |
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Definition
75% anticline
13% stratigraphic
9% combo traps
2% salt domes
1% faults |
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Term
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Definition
| oil-water contact, where oil is degraded by the flow of water causing an impermeable layer |
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Term
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Definition
the measure of the void space of the rock
*using core analysis and well-logging* |
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Term
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Definition
the measure of the ability of the rock to transmit fluids
*using core analysis and well-logging* |
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Term
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Definition
0-5% negligible Practical cut off for sandstone-8%
5-10% poor limestone-5%
10-15% fair for gas it's lower
15-20% good
>20% very good |
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Term
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Definition
Phi=Vp/Vb=(Vb-Vgr)/Vb
Vp= pore volume
Vb=bulk volume of reservoir
Vgr= grain volume |
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Term
| find Vp and Vb (equation) |
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Definition
Vp=Vb/SG=(Wwet-Wdry)/SG
Vb=AcL=pi(d/2)^2(L) |
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Term
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Definition
N=7,758Ah(Phi)(1-Swi)=7,758Ah(Phi)Soi
Swi= initial water saturation, fraction
Soi=initial oil saturation, fraction |
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Term
| Stock tank oil initially (equation) |
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Definition
N=7758(Ah(phi)(1-Swi))/Boi
Boi=reservoir barrels per stock tank barrel or bbl/STB |
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Term
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Definition
| G=43,560(Ah(phi)(1-Siw))/Bgi |
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Term
| Bgi, initial gas deviation factor or compressibility factor (equation) in rankins |
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Definition
Initial gas formation volume factor in ft^3/SCF
Bgi=0.02829(ZiT/Pi) |
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Term
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Definition
1. rock grain size
2. grain shape
3. grain size distribution (sorting)
4. grain packing
5. the degree of consolidation and cementation |
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Term
| what is good permeability? |
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Definition
<1 millidarcy- poor or tight
1-10 md-fair
10-100 md-good
100-1000 md- very good |
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Term
| Measurement of permeability (equations) |
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Definition
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Term
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Definition
k=quL/(P1-P2)A (darcy)
k=quL/1.127x10^-3(P1-P2) |
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Term
| Oil well prodduction rate (equation) |
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Definition
| q=.00708kh(Pe-Pw)/UoBo[ln(re/rw)+S] |
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Term
| Gas well production rate (equation) |
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Definition
| q=kh(Pe^2-Pw^2)/1422UgZT[ln(re/rw)+S] |
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Term
| reasons for (SKIN) formation damage |
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Definition
1. invasion by drilling fluids
2. Partial well penetration
3. partial completion
4. plugging of perforation
5. organic/ inorganic precipitation
6. improper perforation density
7. bacterial growth
8 dispersion of clays
9 presence of a mud cake and of cement
10. presence of a high gas saturation around wellbore |
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