Geology Basics2 - General Geology - Lecture Notes, Study notes for Geology. National Institute of Industrial Engineering
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gajjbaahu12 April 2013

Geology Basics2 - General Geology - Lecture Notes, Study notes for Geology. National Institute of Industrial Engineering

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Lithosphere, Based on Physical Properties, Aluminum, Oxygen, Silicon, Phosphorous, Metamorphic Rock, Metamorphism, Horizontal Normal, Disconformity, Nonconformity, Unconformity, Convergent Plate Boundaries
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19

Detailed Features of Ocean-Ocean Collision

Detailed Features of Continent-Ocean Collision Orogeny

Detailed Features of Continent-Continent Collision Orogeny

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Major Plates of the World

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GEOPHYSICS

Waves: S-Waves (Transverse waves) propagate by a pure shear in a direction perpendicular to the direction of wave travel.

Body Waves can propagate through the body of an elastic solid and are nondescriptive. Velocity of Body waves remains same by changing frequency. Two types as:

P-Waves (Longitudinal waves) propagate by compressional dilation uniaxial strains in the direction of wave travel. Rayliegh Waves propagate along boundary between two dissimilar solid media, in a plane perpendicular to the surface and containing the direction of propagation.

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Surface Waves can propagate only along the boundary of solid. Two types are:

Love Waves are polarized shear wave with an associated oscillatory particle motion parallel to the free space and perpendicular to the direction wave motion.

Resolution:

• It is a measure of ability to see two events separately in seismogram. • Two types are: 1. Vertical Resolution 2. Horizontal Resolution

Multi Channel Seismic Reflection Surveying:

• It is the survey in which energy refracted record at different geophones from same signal shot.• The two most common shot-detectors configurations in 2D as:1. Split or Straddle Spread 2. Single ended Spread.

Seismic Reflection Survey

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2D Seismic Surveying: • It gives vertical plane of profile in which shots and detectors are spread linearly.• It gives the area of selected location.

3D Seismic Surveying:

• It gives 3D vision profile in which shots and detectors are spread disorder or non linear. • It gives the volumetric data of selected location.

Sources and Detectors:

• The main detector is geophone while in case of marine survey hydrophones are used.• The main sources are:

1. Air Guns and Water Guns 2. Tail buoy 3. Streamers 4. Pinjers 5. vibrators 6. sparkers

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The Main Sources

CDP Surveying:

• It is the most accurate field method for gathering subsurface reflections and computing velocity from the NMO effect.

• It is possible only in case of horizontal strata and failed in dipping strata. • In 2D it is known as CDP profiling. • It increases the improvement of SNR.

VSP Surveying:

• It is the form seismic reflections surveying that utilize boreholes. • Shots are normally fixed at surface of the well head and recorded at different depths within the

borehole using special detectors clamped to the borehole wall. Seismic Stratigraphy: It is the Analysis of reflection sequences as the seismic reflection of lithologically distinct depositional sequences. Normal Moveout (NMO):

• It is the difference in travel time between reflected arrivals and zero offset. • NMO=> ?�T= x² / 2V² to • It is very useful for determining depth and velocity.

Dip Moveout (DMO):

• It is the difference travel time of rays reflected from dipping strata to receives at equal or opposite offsets.

• DMO => ?�T= 2x sinT� / V Static Correction:

• It is uniformly on all traces and applied for correcting time difference due to surface irregularities which may be of:

1. Elevation difference between individual shots and detectors because of undulating or topographic surface.

2. The presence of weathered layer which has low seismic velocity. Dynamic Correction:

• It is applied to remove the offset of normal Moveout which is produced by horizontal strata.

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Multiples: • They are the reflectors where rays are reflecting at the same reflection more then one time. • Long Path Multiples generate discrete pulse length, when time difference is more between

primary and secondary reflection. • Shot Path Multiples generate extended pulse length, when time difference is less between

primary and secondary reflection. Migration:

• It is the process of reconstructing a seismic section so that reflections events are repositioned under their correct surface location and at a corrected vertical reflection time.

• It also improves the resolutions of seismic solutions by focusing energy spread over a Fresnel zone and by collapsing diffraction pattern produced by point reflector and faulted beds.

• Four types of migration are: 1. Time Migration 2. Depth Migration 3. 2D Migration 4. 3D Migration

Bright Spot Technique: It is used for locating hydrocarbon accumulation which is on true seismic section by localized zones of anomously strong reflections. Flat Spot Techniques: It is horizontal or near horizontal reflections events discordant to the local geological dip which is the indication of the absence of hydrocarbon or bright spot. Bow Tie Effect: It is the event of syncline which is resulting from the existence of discrete reflections points for any surface locations. Subsurface Mapping Procedure:

Data Validation

Data Interpretation

Data Extraction

Mapping

Review

Done

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Projection of Well:

1. Plunge Projection 2. Strike Projection 3. Up or down dip Projection 4. Normal to the section line Projection 5. Parallel to Fault Projection

Types of Geophysical Maps:

1. Time Structure Map 2. Depth Contour Map 3. Log Map 4. Reservoir Analysis Map (RAM) 5. Facies Analysis Map (FAM)

3D Views:

1. Fence Diagrams 2. Isometric Projections 3. Log Maps 4. 3D Reservoir Analysis Model

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PETROLEUM GEOLOGY Petroleum Play:

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1. Reservoir 2. Trap 3. Seal or Cap 4. Secondary Hydrocarbon Migration 5. Primary Hydrocarbon Migration 6. Hydrocarbon Accumulation and Maturation 7. Source

• Organic Marine Organisms tends to generate oil whereas that from higher land plants tends to generate gas.

• Petroleum generation is a time and temperature dependent process. • Petroleum from the thermal breakdown of Kerogen requires a threshold temperature of 50º-60ºC. • Primary migration of petroleum most often occurs during the main phase of oil generation. • In some sedimentary basins, significant (>60 miles) and vertical (>3000 feet) migration of petroleum

can occur. • C1 –C7 Light Gas Hydrocarbon • C8 –C14 Condensate type Hydrocarbon • C15+ Hydrocarbon and Non Hydrocarbon Trap Secondary Migration Source Rock Primary Migration Reservoir: • Argillaceous Marine or Non Marine Rock covered with Cap or Seal. • Porous and Permeable Rock which contain Hydrocarbon (Gas, Oil and Water). • Fluid Condition which may be Static or Dynamic.

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Reservoir Classification:On the Basis of:

Formation Procedure Origin and Enviornament Porosity and Permeability 1. Fragmental / Clastic /

Detridal formed by deposition which has size colloidal from 1/256mm (Mud) to 256mm (Boulder).

2. Chemical Reservoir Rock formed by precipitation, evaporation or deposition of insoluble precipitates.

3. Miscellaneous Reservoir Rock formed by fracturing which may be sedimentary, igneous or metamorphic in nature.

1. Marine Reservoir Rock deposited in ocean basin or sea water.

2. Non Marine Reservoir Rocks deposited in fresh water, brackish water or glacial water.

1. Sandstone Reservoir Mechanical Porosity and Permeability.

2. Carbonate Reservoir Chemical Porosity and Permeability.

1. Sandstone Reservoir • The best Sandstone Reservoir is those that are composed of primarily quartz grains of sand size,

silica cement with minimal fragmented particles.• Particular Grain Size between 62µ�m to 2mm.• Porosity and Permeability depend upon degree of Compaction.• They are generally 25m thick, lenticular and linear spatially, less than 250km² in Area.• The range in age from the oldest being Cambrian (in Pakistan/Algeria) to the youngest being

Pliocene (Caspian Region in Ukraine) and Miocene in Pakistan. In USA, two thirds of the sandstone reservoirs are of Cenozoic age.

• Sandstone Reservoirs forms extensive Stratigraphic Traps.• Nearly 1mbbls of oil (42 gallon per barrel) contain sandstone reservoir of 1 sq. km in size with

an average porosity of 15%, 1m thick and saturated with oil contains 15x10^4 m³ of oil in place.• Initial Porosity/Permeability is controlled by grain size, sorting and packing.• Permeability decreases with grain size and with poorer sorting.• Porosity varies with sorting e.g. 28% for v. poor sorting while >42% for v. well sorting.• Secondary changes include the authigenesis of clay and cement (e.g. Quartz, Calcite) in pore

space can cause a major loss of porosity. 2. Carbonate Reservoir

• They are characterized by extremely heterogeneous porosity and permeability depend on: a. Environment of deposition b. Digenetic alteration of the original rock fabric.

• Main Porosity types are: 1. Vuggy or Intercrystalline 2. Intergranular 3. Intragranular or Cellular 4. Chalky

• Diagenetic events leading changes in porosity and permeability: 1. Dissolution (Leaching): normally improves porosity and permeability 2. Dolomitization: produces generally vuggy porosity but porosity may increase by creating larger

pores or may reduce by the growth of crystals. 3. Fracturing: brecciation, faulting and jointing aids permeability. 4. Recrystallization: by adding neomorphism of micrite into larger crystal size enhances porosity. 5. Cementation: decreases porosity and permeability (pore threats are sealed).• The best sorted carbonate rocks are Oolites which have same grain size and grain shape.• Carbonates are the accumulation of the remains of carbonate secreting animals and plants. It may

form in layers at slopping platforms like shelves in shallow warm saline water. It may also form as linear or continuous reef trends, as in the case of Jhill Limestone (Unit of Gaj Formation).

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Trap: • Term ‘Trap’ was 1st introduced by McCullough in 1934.• It is the Accumulation of Petroleum Hydrocarbons in a reservoir rock when its migration and escape

is prevented.• It reserves the hydrocarbons in porous and permeable rocks.• It obstructs their escape from reservoir rocks by suitable cap rock. General Trap Classification: on the basis of Trap Geometry. Folded Faulted Stratigraphic Salt Domes/Diapric Non-Convex

1.Convex 2.Bending 3.Drapped 4.Compressional 5.Rollover Anticline 6.Buckle 7.Extensional 8.Diapric 9.Contractional

1. Normal 2. Reverse 3. Fractured 4. Thrusted 5. Horst 6. Graben 7. Gravitational

1. Primary 2. Permeability 3. Lithologic 4. Secondary 5. Pinchout 6. Reef 7. Depositional 8. Diagenetic 9. Truncational

1. Mud Diapric 2. Piercement 3. Deep Domes 4. Salt Diapric 5. Clay Diapric 6. Intermediate Salt Domes

1. Depositional Wedgeout

2. Erosional Wedgeout 3. Isolated Lenticular

Bodies 4. Hydrodynamics 5. Paleotopographic 6. Traps Fluid Traps 7. Fault Cutt off Traps

Trap Classification by Allen and Allen: On the basis of process causing Trap Formation:

1. Tectonic 1. Extensional 2. Contractional

2. Compactional 3. Drapped Structure 3. Diapric 4. Salt Movement

5. Mud Movement

1. Structural

4. Gravitational Structure 5. Depositional 6. Reefs

7. Pinchout 8. Channels 9. Bars

6. Unconformity 10. Truncation 11. Onlap

2. Stratigraphic

7. Diagenetic 12. Mineral 13. Tarmats 14. Gas Hydrates 15. Permafrost

3. Hydrodynamic

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Some Associated Trap Figures

D. Salt Dome Salt Plug Stages:

1. The Pillow stage intrusion of the overlying sediments has taken place (Trap Form ‘Domes’) 2. Diapir Stage thick clastics may Pinchout onto the flanks of the plug (Trap Form ‘Stratigraphic’) 3. The Post Diapir Stage as the Diapir grows salt is depleted and it can only continue to rise by

complete detachment from the mother salt.

Please register PDFcamp on http://www.verypdf.com/, thank you.

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Seal or Cap: Factors affect the cap rock effectiveness are:

1. Lithology • Clastic Rocks which have small pore size like Clays and Shale.• Evaporates Rocks like Anhydrite Gypsum and Rock Salt.• Organic rich rocks like Oolitic Limestone, Reefal Limestone.• About 40% recoverable oil reserves are from oil fields caped by evaporates while 60% by

different types of Argillaceous rocks especially Shale.• About 34% are caped by Evaporates for Gas Fields while for Oil Fields about 66% capped by

shales. 2. Ductility (Less prone to Faulting) has following decreasing order:Salt----Anhydrite----Organic rich Shale----Shale----Silty Shale----Calcareous Mudstone----Cherts 3. Thickness

• Enogh to ensure cap pressure. • Thick cap rock improves the chances of maintaining a seal over the entire basin. • Cap rock thickness ranges from 10s m to 100s m.

4. Lateral Continuity The search of the petroleum is focused on the base of regional seal, rather than in any particular reservoir horizon in other words cover broad area.

5. Burial depth of Cap rock not an important factor but maximum depth may be important:• Western Europe 84% 2000 to 3000m• Africa 66% 2000 to 3000m• Middle East 59% 1000 to 2000m• North America 54% <1000m

Secondary Hydrocarbon Migration: The process where hydrocarbons move through a permeable carrier rock to the reservoir rock until they are trapped in the subsurface by an impervious layer and following conditions are necessary for being migrated hydrocarbons:

1. Larger Pore Spaces 2. Fewer Capillary restrictions 3. Less semisolid or Structure Water 4. Less Fluid Pressure

Primary Hydrocarbon Migration: The process where Hydrocarbons move out of their fine grained source rock. A number of Primary Migration has been proposed in which:

• For organic rich rocks 1. Oil Phase Migration 2. Organic Network Migration

• For organic Lean rocks 3. Molecular Solution 4. Micellar or Colloidal Solution 5. Diffusion Mechanism 6. Gas Phase Migration

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Source Rock Evaluation:

1. Organic Richness 2. Type of Organic Matter 3. Level of Hydrocarbon generation and maturation 4. Expulsion efficiency of the generated Hydrocarbons

Principle Methods of source evaluation are: • Organic Richness

1. Total Organic Carbon Content (TOC) 2. Rock Eval Pyrolysis Analysis or Total Hydrocarbon Yield (THY) 3. C15+ Extractable Bitumen and Hydrocarbons (THC)

• Organic Quality 4. Visual Kerogen Assessment 5. Elemental Analysis 6. Pyrolysis

• Thermal Maturity 7. Vitrinite Reflectance Analysis (%RO) 8. Thermal Alteration Index (TAI) 9. Pyrolysis (T-max oC) 10. Geochemical Parameters

Total Organic Carbon: TOC for Shales % TOC for Carbonates % Descriptive Terminology

0.00 – 0.50 0.50 – 1.00 1.00 – 2.00 2.00 – 4.00 4.00 – 8.00+

0.00 – 0.12 0.12 – 0.25 0.25 – 0.50 0.50 – 1.00 1.00 – 2.00+

Poor Fair

Good Very Good Excellent

Rock Eval Pyrolysis: The four Primary Rock Eval Parameters are:

1. S1 – Quantity of free or absorbed Hydrocarbons in rock. 2. S2 – Quantity of Hydrocarbons generated during Pyrolysis of Kerogen. 3. S3 – Quantity of CO generated during Pyrolysis of Kerogen. 4. Tmax – Temperature of maximum S2 Generation.

C15+ Total Hydrocarbon Content THC (ppm w/w) Descriptive Terminology

0 – 50 50 – 100 100 – 200 200 – 400 400 – 800

800+

Very Poor Poor Fair

Good Very Good Excellent

Vitrinitic Reflectance Analysis: Vitrinitic Reflectance (%RO) Associated Hydrocarbon Types

0.30 – 0.35 0.35 – 0.60 0.60 – 0.80 0.80 – 1.20 1.20 – 1.50 1.50 – 2.00

2.00+

Biogenic Gas Biogenic Gas and Immature Oil

Immature Heavy Oil Mature Oil

Mature Oil, Condensate, Wet Gas Condensate, Wet Gas

Petrogenic Methane Gas

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Important Indices:

Indices Symbol Farmula Hydrogen Index HI S2/TOC Oxygen Index OI S3/TOC, (S1/( S1+ S2)) Thermal Index TI S1/TOC

Maturation Index MI S0/ S1 / S1+ S2+ S3, oil and gas shows S0+ S1 Genetic Potential GP S0+ S1+ S2 Potential Yield PY S1+ S2

Sedimentation Rate:

Low High Oxic Environment No source rock Gas prone source rock

Anoxic Environment

Lean oil prone source rock

Oil rich prone source rock

Requirements for deposition and preservation of Effective Source Rock:

• High Organic Matter input• High Oil Proclivity of Organic Material.• Short Transport History• Anoxic depositional condition with concentrated bacterial activity• Low energy system

Kerogen:

Kerogen Type Kerogen Name Associated

Organic Matter Type

Associated Organic Matter

Associated Hydrocarbon

1. Type I Sapropelic Kerogens Alginite Amorphous very oil prone 2. Type II Exinitic Kerogens Exinite Herbaceous oil prone 3. Type III Vitrinitic Kerogens Liptinite/Vitrinite Woody mainly gas prone 4. Type IV Inertinitic Kerogens Inertinite Coaly inert gases Transformation of Organic Matter: Potential

Source Temperature Processes Main

Product Bi-Product

1. Diagenesis Biological Matter

<50ºC low Hydrolysis, Decarboxylation,

Condensation, Polymerization

Kerogen (90%)

Biogenic Methane,

Water, CO2

2. Catagenesis Immature Kerogen

50º – 150ºC int Thermal Breakdown,

Bond Cracking, Aromatization

Wet Gas Hydrocarbons,

Late Mature Kerogen

Water, CO2

3. Metagenesis Late Mature Kerogen

>150ºC high Bond Cracking, Aromatization

Residual Kerogen

Methane and Inorganic gases

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Depositional Environments and their effects on preservation:

Depositional Environment

Depositional Environment Conditions

Source of Organic Matter

Type of Organic Matter

Preservation of Organic Matter

Hydrocarbon Potential

Peat/Coal Swamp Low energy anoxic Terrestrial

Woody/Hu mic

High amounts unoxidized

Minor to moderate oil

and gas

Eutrophics Lakes

Low energy partially oxic Terrestrial

Woody/Hu mic and Algal

High amounts relatively

unoxidized

Oil and gas if preserved

Fluvial/Deltaic/ Coastal High energy oxic Terrestrial

Woody/Hu mic

Low amounts oxidized

Mainly gas with minor oil

Stratified Lake Low energy anoxic Lacustrine Algal High amounts unoxidized Good to very

good oil

Coastal High energy anoxic Marine Algal Low to moderate amounts partially

oxidized

Minor to moderate oil

and gas

Continental Shelf

Moderate to low energy anoxic Marine Algal

High amounts unoxidized

Moderate to good oil and

gas

Open Ocean Low energy variable conditions Marine Algal Low to moderate amounts variably

oxidized

Very poor oil and gas

Burial History Plot:

• Sedimentation Rate • Structure of an Area • Unconformity • Age of the Reservoir • Temperature analysis by means of Depth • Rate of Trap Formation is determined by Rt = ?�D/?�T

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RESERVIOR CONCEPTS

Introduction of Dimension and Unit There are two types of Dimensions:

1. Primary Dimension 2. Secondary Dimension

There are two types of Fundamental units: 1. International or MKS System of Fundamental Units (SI Units) 2. British Engineering or FPS System of Fundamental Units (BG Units)

Primary Dimensions

SI Units (MKS) BG Units (FPS)Conversion Factor

Length (L) Meter (m) Foot (ft) 1ft = 0.3048 m, 1 m = 3.3 ft Mass (M) Kilogram (kg) Slug (slug) 1 slug = 14.59391kg

1 kg = 0.0685slug Force Newton (N) Pound (lb) Time (T) Second (s) Second (s) Temperature Degree Celsius (°�C)

Kelvin (°�K) (at absolute Scale) °�K= °�C + 273

Degree Fahrenheit (°�F) Rankin (°�R) (at absolute Scale) °�R = °�F + 459.69

1 °�K = 1.8 °�R 1 °�R = 0.556 °�K

Secondary DimensionsSI Units (MKS)

BG Units (FPS)

Conversion Factor

Area (L²) m² ft² 1 m² = 10.764 ft², 1 ft² = 0.0929 m² Volume (L³) m³ ft³ 1 m³ = 35.315 ft³, 1 ft³ = 0.0823 m³ Velocity (L/T ) m/s ft/s 1 ft/s = 0.3048 m/s, 1 m/s = 3.28 ft/s Acceleration (L/T²) m/s² ft/s² 1 ft/s² = 0.3048m/s²,

1 m/s² = 3.28 ft/s² Pressure or Stress (M/(LT²)) Pa = N/m² lb/ft² 1 lb/ft² = 47.88 N/m²,

1 N/m² = 0.0209 lb/ft² Angular Velocity (1/T or T?�) s?� s?� 1 s?� = 1 s?� Energy, Heat, Work (ML²/T²) J = N.m ft-lb 1 ft-lb = 1.3558 J, 1 J = 0.7376 ft-lb Power (ML²/T³) W = J/s (ft-lb)/s 1 (ft-lb)/s = 1.3558 W,

1 J = 0.7376 ft-lb Density (M/L³) kg/m³ slugs/ft³ 1 slugs/ft³ = 515.4 kg/m³,

1 kg/m³ = 0.00194 slugs/ft³ Viscosity (M/(LT)) kg/(m.s) slugs/(ft-s) 1 slugs/(ft-s) = 47.88 kg/(m.s),

1 kg/(m.s) = 0.0209 slugs/(ft-s) Specific Heat (L²/(T²?�)) m²/(s².°�K) ft²/(s²-°�R) 1 m²/(s².°�K) = 5.98 ft²/(s²-°�R),

1 ft²/(s²-°�R) = 0.1672 m²/(s².°�K) Unit Consistency: it is especially true of the oil industry as it has its own specific units.Quantity Oil

Industry Unit

Conversion into SI units Conversion into BG units

Volume BBL 1 BBL = 0.1589 m³ 1 BBL = 5.612ft³ Pressure psi 1 psi = 6894 Pa 1 psi = 144.0846lb/ft² Viscosity cp 1 cp = 0.001 Pa.s 1 cp = 0.14409(lb-s)/ft² Flow Rate BBLS/D 1 BBLS/D = 1.84 x 10^-6 m³/s 1 BBLS/D = 6.5 x 10^-5 ft³/s Area acres 1 acres = 4046 m² 1 acres = 43351.144ft² 1 mile = 1.65 km 1 day = 3.1 x 10^-8 yr 1 N/ m³ = 6.37 x 10^-3 lb/ ft³

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Thermodynamic Properties of Fluid

Fluid PropertiesFormulaConstant termsConversion Factor 1. Pressure (p) p = znRT/V

p = ?�RT/m p = ?�RT pr = p / pc ppr = p / ppc

R = 10.73 psia ft³ lb-mole °�R R = 82.06 atm cm³ g-mole, K R = 62.37 mm Hg litters g-mole, K

1 atm = 14.7 lb/in² = 2116 lb/ft² = 101,300 Pa = 101.3 kPa

2. Density (?�) ?� = M/V ?� = ?� /g ?� = mp/RT

At 20°�C and 1 atm. ?�air = 1.205 kg/m³ = 0.0024slugs/ft³ ?�water = 998 kg/m³ = 1.94slugs/ft³

3. Temperature (T) Tr = T / Tc Tpr = T / Tpc

°�R = °�F + 459.69 °�K= °�C + 273

1 °�K = 1.8 °�R 1 °�R = 0.556 °�K

4. Specific or unit Weight (?�)

?� = p/RT ?� = 1 / V ?� = ?�g

At 20°�C and 1 atm. ?�air = 11.8 N/m³ = 0.0752 lb/ft³ ?�water = 9790 N/m³ = 62.4 lb/ft³

5. Specic Gravity (SG)

SGgas = ?�gas /?�air SGliquid = ?�liquid /?�water SGgas = ?�gas / ?�air SGgas = MW/ MWair SGliquid = ?�liquid / ?�water

gearth = 32.174 ft/s² = 9.807 m/s² SGHg = 13.60721 SGwater = 1 SGair = 1

°�API = 141.5/SG – 131.5 SG =141.5/(°�API+131.5) SGgas = ?�gas/1.205 kg/m³ SGliq = ?�liq /9985 kg/m³ SGgas = ?�gas/11.8 kg/m³ SGgas = MW/ 29 SGliq = ?�liq /9790 kg/m³

6. Coefficient of Viscosity (?�)

?� = µ� / ?� ?� is kinematic viscosity in centistokes. µ� is absolute viscosity in centipoises. ?� is density in gm/cm³.

1.5 – 2 centipoises at 50 °�F 0.7 – 1 centipoises at 100 °�F 0.4 – 0.6 centipoises at 150 °�F

7. Surface Tension (s�)

8. Capillarity (h)

s� = rh?� / 2cos?� s� is surface tension. r is radius of tube. h is height of capillary. rise or depression. ?� is sp.weight of liquid. ?� is wetting angle.

If tube is clean, ?� = 0°� for water ?� = 140°� for mercury

9. Isothermal Conditions

p1V1 = p2V2 ?�1 / ?�2 = p1 / p2 = constant E = p

10. Formation Volume Factor (Bo)

Bo = Vres / Vsc = z T Psc / zsc Tsc p

Psc = 14.7 psia, zsc = 1, Tsc = 520 °�R in bbls/SCF ÷ by 5.615

Bg = 0.0283 z T / p ft³/SCF Bg = 0.005034 z T / p bbls/SCF

11. Isothermal Compressibility (Co)

Co = Cpr / ppc

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General Properties of Gases Fluid PropertiesFormulaConstant termsConversion Factor

1. Atomic Weight unit (a) Molecular Weight unit (M)

M = m / n Mair = 28.97

2. Mole & Pound m = nM Avogadro No = 2.733×10^26 1 Mole = 30.07pound (lb) 3. Density (?�) ?� = M/V

?� = ?� /g ?� = Mp/RT

At 20°�C and 1 atm. ?�air = 1.205 kg/m³ = 0.0024slugs/ft³ ?�water = 998 kg/m³ = 1.94slugs/ft³

4. Pressure (p) p = znRT/V p = ?�RT/m p = ?�RT pr = p / pc ppr = p / ppc pc = S� gi pci

R = 10.73 psia ft³ lb-mole °�R R = 82.06 atm cm³ g-mole, K R = 62.37 mm Hg litters g-mole, K

1 atm = 14.7 lb/in² = 2116 lb/ft² = 101,300 Pa = 101.3 kPa

5. Temperature (T) Tr = T / Tc Tpr = T / Tpc Tc = S� gi Tci

°�R = °�F + 459.69 °�K= °�C + 273

1 °�K = 1.8 °�R 1 °�R = 0.556 °�K

6. Specific or unit Weight (?�)

?� = p/RT ?� = 1 / V ?� = ?�g

At 20°�C and 1 atm. ?�air = 11.8 N/m³ = 0.0752 lb/ft³ ?�water = 9790 N/m³ = 62.4 lb/ft³

7. Specic Gravity (SG)

SGgas = ?�gas /?�air SGgas = ?�gas / ?�air SGgas = MW/ MWair

gearth = 32.174 ft/s² = 9.807 m/s² SGHg = 13.60721 SGwater = 1 SGair = 1

°�API = 141.5/SG – 131.5 SG =141.5/(°�API+131.5) SGgas = ?�gas/1.205 kg/m³ SGgas = ?�gas/11.8 kg/m³ SGgas = MW/ 29

8. Isothermal Conditions

p1V1 = p2V2 ?�1 / ?�2 = p1 / p2 p1V1/T1 = p2V2/T2 =constant

9. Formation Volume Factor (Bg)

Bg = Vres / Vsc = zTPsc/zscTscp

Psc = 14.7 psia, zsc = 1, Tsc = 520 °�R in bbls/SCF ÷ by 5.615

Bg = 0.0283 z T / p ft³/SCF Bg = 0.005034 z T / p bbls/SCF

10. Isothermal Compressibility (Cg)

Cg = Cpr / ppc

Standard constant terms: V = 379.4 ft³, p = 14.7 psia, T = 60°�F + 459.69 = 520 °�R, R = 10.73 psia ft³ lb-mole °�R, pr = reduced pressure, pc = critical pressure, ppr = pseudo reduced pressure, ppc = pseudo critical pressure, Tr = reduced temperature, Tc = critical temperature, Tpr = pseudo reduced temperature, Tpc = pseudo critical temperature.

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Permeability Concept

1. Permeability The ability to flow is permeability. kro = (1- Sw - Swi )² 1- Swi – Sor krw = Sw Sw - Swi 1- Swi Absolute permeability ka = 1.2 × 10³ f� Effective permeability of oil is given by: kroe = kro * ka Effective permeability of water is given by: krwe = kwo * ka Kro = Ko/K Kwo = Kw/K Kw + Ko = 1 Kw + Ko + Kg = 1

2. Saturation: Sw + So = 1 Sw + So + Sg = 1

3. Flow rates: Q = KA (?�P)/µ�L Qw = kroe A (?�P)/µ�o L Qo = kroe A (?�P)/µ�o L

4. Volume: Volume of grain => Vg = n (4/3) p� r³

5. Porosity: f� = (Vb – Vg)*100 / Vb

Fluid Flow in Reservoir Series / Harmonic Mean => Qt = Q1 = Q2 = Q3 => P1 – P2 = ?�P1 = ?�P2 = ?�P3 p2 p1 => L = L1 + L2 + L3 = S� Lj K3 K2K1 1/k = 1/L S� (Li/ki) ?�P1 ?�P2 ?�P3 Q Radial System: k = (log re/rw) / S� log (rj/rj – 1) / ki Heterogeneous System / Geometric Mean: h L1 L2 L3 log k = 1/n S� log ki Flow rate: Q = (KA/µ�) (?�P/L + ?�g sin ?�) W L Parallel / Arithematic Qt = Q1 + Q2 + Q3 P2 P2 At = A1+A2+A3 k = 1/A S� KiAi h1 A1 K1 Q1 Q h2 A2 K2 Q2

h3 A3 K3 Q3

W L

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Volumetric Calculation Volumetric Calculation by different Farmulae:

• Formula 1: ?�V = h/2(An + An+1) For Trapezoid ?�V = Ah/3 for Pyramid

• Formula 2: ?�V=h/2(An+An+1+(An*An+1)1/2 ) For Successive Trapezoid ?�V = Ah/3 for Pyramid

• Formula 3: ?�V = h/2 (Ao+2A1+2A3+…… . . + 2An-1+An) + Avg.A Pressure by Different formulae:

• Reservoir or Well Pressure = S� p/n • Area Average pressure = S� pA / S�A • Volume Average Pressure = S� pAh / S�Ah

Net thickness of Reservoir:

• Net thickness of Reservoir = Total thickness - (shale + impervious sandstone + claystone) Hydrocarbon In Place

• OOIP = 7758(Ahf�(1-Sw))/Bo (in STB) • Gas MMSCF = 43.58(Ahf�(1-Sw))/Bg (in MMSCF) • Initial Gas in Place is, G1 = 43560 (f�* 1-Sw *A*h) / Bgi

Recovery Reserves Concepts:

• Recovery gas volume = 43560 f� (1- Sw) • Unit Recovery = Reservoir gas volume (1/Bgi – 1/Bga) • Recovery Factor = (1 – (Bgi/Bga ))*100 • Recovery Factor = ((1-Swi)/Bgi – Sgr/ Bga)/ ((1-Swi)/Bgi) *100 • Unit Recovery = 43650 f� ((1-Swi)/Bgi – Sgr/Bga) • Recovery gas volume = 43560 f� Sgr

Gas Gravity:

• gas gravity = S� yj Mj / Mair • gas gravity = MWg/MWair

Pseudocritical Properties by browns approximation:

• Tpc = 167 + 316.678 gas gravity • ppc = 702.5 – 50 gas gravity

Coefficient of Viscosity:

• Y1 = (9.4 + MWg) (T+ 460)^1.5 (209+19MWg+T+460)

• Y2 = 3.5+0.01MWg + (986/ (T+460)) • Y3 = 2.4 – 0.2Y2 • Y4 = 0.00752*(MWg/Bg)• Y5 = Y2 (Y4^Y3) • µ�g = (Y1 (e^Y5))/1000

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BASIN ANALYSYS • A sedimentary basin is an area in which sediments have accumulated during a particular time period at a

significantly greater rate and to a significantly greater thickness than surrounding areas. • A low area on the Earth’s surface relative to surroundings e.g. deep ocean basin (5-10 km deep),

intramontane basin (2-3 km a.s.l.) • Basins may be small (kms2) or large (106+ km2) • Basins may be simple or composite (sub-basins) • Basins may change in size & shape due to:

1. erosion 2. sedimentation 3. tectonic activity 4. eustatic sea-level changes

• Basins may overlap each other in time • Controls on Basin Formation

1. Accommodation Space, a. Space available for the accumulation of sediment b. T + E = S + W

T=tectonic subsidence E= Eustatic sea level rise S=Rate of sedimentation W=increase in water depth

2. Source of Sediment a. Topographic Controls b. Climate/Vegetation Controls c. Oceanographic Controls (Chemical/Biochemical Conditions)

• The evolution of sedimentary basins may include: 1. tectonic activity (initiation, termination) 2. magmatic activity 3. metamorphism 4. as well as sedimentation

• Axial elements of sedimentary basins: 1. Basin axis is the lowest point on the basement surface 2. Topographic axis is the lowest point on the depositional surface 3. Depocentre is the point of thickest sediment accumulation

• The driving mechanisms of subsidence are ultimately related to processes within the relatively rigid, cooled thermal boundary layer of the Earth known as the lithosphere. The lithosphere is composed of a number of tectonic plates that are in relative motion with one another. The relative motion produces deformation concentrated along plate boundaries which are of three basic types: 1. Divergent boundaries form where new oceanic lithosphere is formed and plates diverge. These occur

at the mid-ocean ridges. 2. Convergent boundaries form where plates converge. One plate is usually subducted beneath the

other at a convergent plate boundary. Convergent boundaries may be of different types, depending on the types of lithosphere involved. This result in a wide diversity of basin types formed at convergent boundaries.

3. Transformboundaries form where plates move laterally past one another. These can be complex and are associated with a variety of basin types.

• Many basins form at continental margins. Using the plate tectonics paradigm, sedimentary basins have been classified principally in terms of the type of lithospheric substratum (continental, oceanic, transitional), the position with respect to a plate boundary (interplate, intraplate) and the type of plate margin (divergent, convergent, transform) closest to the basin.

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• Plate Tectonic Setting for Basin Formation

1. Size and Shape of basin deposits, including the nature of the floor and flanks of the basin 2. Type of Sedimentary infill

• Rate of Subsidence/Infill • Depositional Systems • Provenance • Texture/Mineralogy maturity of strata

3. Contemporaneous Structure and Syndepositional deformation 4. Heat Flow, Subsidence History and Diagenesis

• Interrelationship Between Tectonics - Paleoclimates - and Eustacy 1. Anorogenic Areas------>

• Climate and Eustacy Dominate 2. Orogenic Areas--------->

Sedimentation responds to Tectonism

Plate Tectonics and Sedimentary Basin

Types SB = Suture Belt RMP = Rifted margin prism S C = Subduction complex FTB = Fold and thrust belt RA = Remnant arc

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Wilson Cycle about opening and closing of ocean basins and creation of continental crust.

Structural Controls on Sedimentary Systems in Basins Forming: Stage 1: Capacity < Sediment Fluvial sedimentation Stage 2: Capacity = Sediment Fluvial lacustrine Transition

Stage 3: Capacity > Sediment Water Volume > excess capacity Shallow-water lacustrine sedimentation

Stage 4: Capacity >> Sediment Water volume = excess capacity Deep-water lacustrine sedimentation

Stage 5: Capacity > Sediment Water volume < excess capacity Shallow-water lacustrine sedimentation

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BASIN CLASSIFICATION: Structural

Setting Basin Type Geological Origin Example

Intra-Plate Intracratonic basins Forms within stable continental crustal mass

Congo Basin, Lake Eyre Basin, Peshawar Basin.

Rift Related Basin Large scale mantle convection. Regional updoming ± regional basaltic (flood) volcanism.

Rift basin

The down-dropped basin formed during rifting because of stretching and thinning of the continental crust or Result of continental extension.

East Africa Rift

Passive margin basin Subsidence along a passive margin, mostly due to long-term accumulation of sediments on the continental shelf.

East coast of North America

Aulacogene basins Narrow continental rifts control by normal listric Faults.

D iv

e r

g e

n t

P la

te M

a r

g in

s

Oceanic Rift basins Initially narrow may evolve into open oceanic basins. Red Sea

Subduction Related Basins

Two Plates subducting each other which may be collision between O-O, O-C, C-C

Trench (accretionary wedge) basin

Downward flexure of the subducting and non-subducting plates (sites of accretionary wedges)

Western edge of Vancouver Island, Modern Mariana Islands

Back arc basin Subduction faster than compression Extensional basins Izu-bonin arc-trench system, west pacific

Backarc-foreland basin

Form at active continental margins in association with subduction and the development of island arcs.

Forearc basin

The area between the accretionary wedge and the magmatic arc, largely caused by the negative buoyancy of the subducting plate pulling down on the overlying continental crust

Georgia Strait

Retroarc foreland basinsmechanical subsidence/sediment loading

Rocky Mountain Western interior C

o n

v e

r g

e n

t P

la te

M a

r g

in s

Peripheral foreland basinstectonic/sediment loading

“Molasses" deposits of the Catskill (Devonian) Deltas, Himalayan Neogene Siwalik Hills.

Strike Slip related Basin strike-slip along non-linear faults

Transtensional Basins

Mechanical and Thermal Subsidence/Uplift of A pull-apart block (e.g. between two transform faults) that subsides opening "holes" or basins at fault jogs or bends

Salton Trough (Neogene; So CA, San Andreas Fault system, USA)

T r

a n

s f

o r

m M

a r

g in

s

Transpressional BasinsMechanical Subsidence/Uplift

Ridge Basin (Neogene; So CA, San Andreas Fault system, USA)

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Rift Basin Passive Margin Basin

Trench Basin and Fore Land Basin Trench Basin and Forearc Basin

Transtensional Basin or Pull-apart Basin

Transpressional Basin

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