Springs,Hot Springs,Geysers,How Geysers Work

Springs:
Not until the middle of the seventeenth century did the French physicist Pierre Perrault invalidate the age-old assumption that precipitation could not adequately account for the amount of water emanating from springs and flowing in rivers. Over several years, Perrault computed the quantity of water that fell on France’s Seine River basin. He then calculated the mean annual runoff by measuring the river’s discharge. After allowing for the loss of water by evaporation, he showed that there was sufficient water remaining to feed the springs. Thanks to Perrault’s pioneering efforts and the measurements by many after ward, we now know that the source of springs is water from the zone of saturation and that the ultimate source of this water is precipitation.

           Whenever the water table intersects Earth’s surface, a natural outflow of groundwater results, which we call a spring (Figure 17.18).

Springs such as the one pictured in Figure 17.18 form when an aquitard blocks the downward movement of groundwater and forces it to move laterally. Where the permeable bed crops out, a spring results.which shows a perched water table intersecting a slope.

         Springs, however, are not confined to places where a perched water table creates a flow at the surface. Many geologic situations lead to the formation of springs because subsurface conditions vary greatly from place to place. Even in areas underlain by impermeable crystalline rocks, permeable zones may exist in the form of fractures or solution channels. If these openings fill with water and intersect the ground surface along a slope, a spring results.

Hot Springs:

There is no universally accepted definition of hot spring. One frequently used definition is that the water in a hot spring is 6° to 9° C (10° to 15° F) warmer than the mean annual air temperature for the locality where it occurs (fig 17.9)

In the United States alone, there are more than 1000 such springs.

             Temperatures in deep mines and oil wells usually rise with increasing depth, an average of about 25° C per kilometer, a figure known as the geothermal gradient. Therefore, when groundwater circulates at great depths, it becomes heated. If the hot water rises rapidly to the surface, it may emerge as a hot spring. The water of some hot springs in the eastern United States is heated in this manner. The springs at Warm Springs, Georgia, the presidential retreat of Franklin Roosevelt (Figure 17.19B), are one example. The temperature of these hot springs is always near 32°C (90°F). Another example is Hot Springs National Park, Arkansas, where water temperatures average about 60° C (140° F)

          The great majority (more than 95 percent) of the hot springs (and geysers) in the United States are found in the West. A glance at (fig 17.20) 

reinforces this fact.The reason for such a distribution is that the sources of heat for most hot springs are magma bodies and hot igneous rocks, and it is in the West that igneous activity has occurred more recently. The hot springs and geysers of the Yellowstone region are well known examples.

Geysers:

Geysers are intermittent hot springs or fountains in which columns of water are ejected with great force at various intervals, often rising 30 to 60 meters (100 to 200 feet) into the air. After the jet of water ceases, a column of steam rushes out, usually with a thunderous roar. Perhaps the most famous geyser in the world is Old Faithful in Yellowstone National Park (fig 17.21)

. The great abundance, diversity, and spectacular nature of Yellowstone’s geysers and other thermal features undoubtedly was the primary reason for its becoming the first national park in the United States. Geysers are also found in other parts of the world, notably New Zealand and Iceland. In fact, the Icelandic word geysa, meaning “to gush,” gives us the name geyser.

How Geysers Work:

Geysers occur where extensive underground chambers exist within hot igneous rocks. How they operate is shown in FIG 17.22

. As relatively cool groundwater enters the chambers, it is heated by the surrounding rock. At the bottom of the chambers, the water is under great pressure because of the weight of the overlying water. This great pressure prevents the water from boiling at the normal surface temperature of 100° C (212° F). For example, water at the bottom of a 300-meter (1000-foot) water-filled chamber must attain nearly 230° C (450° F) before it will boil. The heating causes the water to expand, with the result that some is forced out at the surface. This loss of water reduces the pressure on the remaining water in the chamber, which lowers the boiling point. A portion of the water deep within the chamber quickly turns to steam, and the geyser erupts (Figure 17.22). Following eruption, cool ground water again seeps into the chamber, and the cycle begins a new.

Geyser Deposits:

When groundwater from hot springs and geysers flows out at the surface, material in solution is often precipitated, producing an accumulation of chemical sedimentary rock. The material deposited at any given place commonly reflects the chemical makeup of the rock through which the water circulated. When the water contains dissolved silica, a material called siliceous sinter, or geyserite, is deposited around the spring. When the water contains dissolved calcium carbonate, a form of limestone called travertine, or calcareous tufa, is deposited. The latter term is used if the material is spongy and porous. The deposits at Mammoth Hot Springs in Yellowstone National Park are more spectacular than most others (FIG 17.23)

. As the hot water flows upward through a series of channels and then out at the surface, the reduced pressure allows carbon dioxide to separate and escape from the water. The loss of carbon dioxide causes the water to become supersaturated with calcium carbonate, which then precipitates. In addition to containing dissolved silica and calcium carbonate, some hot springs contain sulfur, which gives water a poor taste and unpleasant odor. Undoubtedly, Rotten Egg Spring, Nevada, is such a situation.

Reservoir Rocks

Reservoir Rocks:

“The rock, which is porous and permeable, contains oil and gas becomes a reservoir rock.” OR

“Permeable subsurface rock that contains petroleum”

It can be different from source rock with respect to grain size and pore spaces.

Nearly all rocks are reservoir and can be classified accordingly as

·         Clastic Rocks

·         Carbonate Rocks

·         Igneous/Metamorphic Rocks

Clastic Rocks

Aggregates of a particle, fragments of older rocks

Range in size from fine clay to boulder size forming various clastic rocks, including claystone, shale, siltstone, sandstone, conglomerates.

Most important reservoir rocks in this category are sandstone and sometimes conglomerate due to porosity and permeability. The fractured shale reservoir is also possible but uncommon in nature.

Carbonate Rocks

Formed by chemical precipitation or biological precipitation.

The most important reservoir in this category are limestone and dolomite.

Igneous/Metamorphic Rocks

These are rare comparatively to clastic and carbonate reservoir rocks, from which commercial oil and gas are produced.

e.g., there are number of volcanic oil fields, which contains oil and gas includes: Columbia Plateaue of Washington and Oregon, the Mexico-Arizona Volcanic field, the Deccan Traps of India and volcanic of pacific.

Reservoir Rocks Properties:

There are two main properties on the basis of which reservoir quality of rocks is controlled.

·         Porosity

·         Permeability

Porosity:

“It is the ratio of pore spaces volume to the total volume (bulk volume) of a reservoir rock.”

It is expressed in %age.

Mathematically: Porosity = Pore volume/Bulk volume x 100

Porosity on the basis of origin

·         Primary Porosity

·         Secondary Porosity

Primary Porosity:

Porosity which developed at time of deposition.

Depends upon; size, shape and pattern of arrangement of grains

e.g., uniform grain size higher the porosity, perfectly rounded shape higher the porosity. In last when packing is cubic of same size grain higher the porosity (47.6%) rather than rhombohedral grains (25.9%).

Secondary Porosity:

Porosity which is developed after the sedimentation process due to physical and chemical effects.

The physical and chemical effects includes

·         Compaction

·         Fracturing

·         Dissolution

·         Cementation

·         Recrystallization

·         Dolomitization

Porosity based on the pore space connectivity Both primary and secondary porosity could be:

·         Absolute Porosity

·         Effective Porosity

Absolute Porosity:

The ratio of total volume of pore spaces to  total volume of rock

Effective Porosity

The ratio of the volume of interconnected pore spaces to the total volume of the rock.

Porosity in Clastic Rocks
(Sandstone)

 There are four basic porosity types within sandstone (after, Pittman, 1979)

·         Intragranular Porosity

·         Intergranular Porosity

·       Dissolution porosity

·    Fractured Porosity

Porosity in Carbonates (Limestone):

 There are many types of porosities within limestone but can be groups together in three groups (after Choquette and Pray, 1970) such as:

1. fabric selective

2.non fabric selective

3.fabric selective or Not

Porosity in Igneous/Metamorphic Rocks:

There might be only a fracture porosity. 

Permeability:

“Ability of a rock to permit fluidflow” through the inter-conneted pores.

 It is expressed by m2. Mathematically it can be written as by Darcy’s law:

q/A= KAP/p AL

q= volumetric flow rates, m3/s A= cross sectional area, m2 K= permeability, m2

AP/AL= pressure gradient in direction of flow, Pa/m p= viscosity, Pa.s

Types of Permeability

Ø  Absolute Permeability

When only one fluid saturate the effective pore spaces and can pass through effective pores.

Effective Permeability

When only one fluid can pass through effective pores in presence of other fluid.

Ø  Relative Permeability

The ratio of effective permeability to the absolute permeability

Geochemical Fossils and Their Significance in Petroleum Formation

Geochemical Fossils and Their Significance in Petroleum Formation

“saturated hydrocarbons having branching chain structure produced by certain organism action”

These come from plant and animals: these are helpful in locating the source on the basis of structure

High molecular having formula: Cn H2n-x: ratio between C:H<2

There are various types of geochemical fossils

Long Chain Paraffin

Complex Ring Alcohols

Triterpentinoid Alcohols

Acyclic Isoprenoids

1. Long Chain Paraffin  Derived from waxes of higher plants

2.Complex Ring Alcohols

Based on cyclohexane and are derived from plants and animals

3.Triterpentinoid Alcohols

These are aromatic compounds based on terpene

Terpene: organic compound having basic structure (C10 H16) or Multiple of (C10 H16) e.g. Steroid having formula (C30 H50 OH) as an alcohol of terpene

4.Acyclic Isoprenoids

Compounds based on isoprene: chemical composition is (C6 H8)

Compounds may have multiple of isoprene

Isoprenoid: formed long branched and saturated molecule, branching is every 4th cation of isoprene having methyl group

Occurs in sediments with abundance derivatives from chlorophyl from plants and hemin form animals

Significance

They are useful indicators of oil origin

Typical example are Pristane and Phytene

Pristane: 2,6,10,14 Tetra methyl pentadecane, it has nineteen carbon in

skeleon

Phytene: Tetra methyl hexadecane, it has twenty carbon in its skeleton

 Ratio of Pristane and Phytene (Pristane:Phytene)

ratio measured chromatographically from oil or rock sample, it indicates the organic matter from which oil is originated or thermal maturation of source.

High ratio indicates large contribution form teristrial OM

The ratio is therefore a vital “finger prints” for any crude oil, containing both molecule.

Finger prints: because it has to identify the source of OM

Catagenesis

Principle Stage of oil formation

T continue to increase, bonds break down e.g., ester and some C-C bonds

H/Cs molecules, and particularly aliphatic chains, are produced from kerogen and from previously generated N, S, O compounds

Some H/Cs are C15-C30, which are comparable to geochemical fossils, entrapped in kerogen or linked by ester bonding.

However, most of new molecule has medium to low molecular weight

This is priciple zone of oil formation, as described by Vassoevich, 1969, however, also some significant amount of gas.

Principle Stage of Condensate and Wet Gas Formation

P-T continues to increase, breaking of C-C bonds occur more frequently

Light hydrocarbons are generated through cracking from remaining kerogen and in petroleum; the quickly dominated compound is methane.

Overall transformation is equivalent to disproportionation;

On one hand H/Cs increasing in Hydrogen content are genereated having average atomic ratio H/C is 1.5 to 2.0 in crude oil and 4.0 in methatne

 On the other hand, the residue kerogen depleted in hydrogen H/C of about 0.5 by the end of catagenesis.

Metagenesis: Dry gas Zone

After most liable material has been eliminated through catagenesis, however, in this stage no significance amounts of H/Cs are generated except some methane

Which may result from cracking of source rock H/Cs and reserviored liquid petroleum

Physiochemical Changes or Transformation of Organic Matter to Petroleum

Physiochemical Changes or Transformation of Organic Matter to Petroleum 
                                                                                                                      

Sedimentary Deposits, contains: (1) Interstitial water, (2) Organic Matter, (3) Microbial Organism and (4) Dissolved Oxygen

O.M unstable, in order to be in equilibrium reacts with O2 (along with other reactions), here, the physiochemical transformation starts.

This transformation cannot be isolated from initial condition of deposition environment to PT condition.

                                                 Stages/Process of Formation of Petroleum

Main stages are; (1) Diagenesis, (2) Catagenesis and (3) Metagenesis

Diagenesis

“Set of physiochemical changes which takes place at shallow depth after deposition”

OR

“Diagenesis is a process through which the system tends to approach equilibrium under condition of shallow burial and through which the sediments normally becomes consolidated”

e.g., porosity reduction in clay (80% to 60%)

Depth: 200m rarely up to 2000m

No significance change in pressure and temperature (no significance)

At such depths transformation is due to biological activity, carried by bacteria (aerobic or anaerobic)

The energy within system, comes through decomposition, which produces CO2, NH3 and H2O; in sand decomposition is quick rather than mud

Eh of interstitial H2O decreased, Eh= Oxidation/Redcution, PH of system would be increased

OM like Protein, Carbohydrates are soluble in water, severely transformed (more or less completely deformed), which form a compound “Polycondensed Organic Compound or geopolymer”. A geopolymer is an organic compound, which is precursor of Kerogen (if plant materia greater, then first step would be peat then bitumen).

V.R: 0.5

Humic acid produced

During close, humic acid are minimum

Catagenesis

The second stage

T: 50-150/200C, P: 300-1000 bars and rarely 1500 bars, which results in new changes

Composition, texture of mineral phase are consumed, mostly in clay fraction, e.g., water expelled, decreased the porosity and increase in salanity

OM progressively changes:

Kerogen produces:

first liquid petroleum

Wet gas (later stage)

Condensate (later stage)

Both oil and gas are associated with amounts of methane

Massive organic deposits; various rank of coal, with methane.

End of Catagenesis:

Dissappearence of aliphatic carbon chain

V.R: 2.0 (beginning of anthracite rank coal)

Further no more generation of petroleum and minor amount of methane (this point is known as natural break)

Metagenesis

The last stage, in evolution of sediments

H and T High (OM may be exposed to magma or hydrothermal effect)

Mineral severly transformed

Early metagenesis:

Only methane produced

Coal is anthracite

Late metagenesis:

Residue of Carbon

Meta anthracite, graphite schist etc.

Factor Effecting Transformation of OM into Petroleum

Starts within reducing environment, transformation requires energy and are:

Ø  Temperature and Pressure

Ø  Bacterial Activity

Ø  Catalytic Reaction

Ø  Radioactive bombardment

(1)Temperature and Pressure

T combined with P or Low T replaced with Time along with pressure

Kerogen shales: 350-400C to convert into petroleum, presence of porphyrines, indicates T never exceeds than 200C (means time is replacing Temp., enough time would be required)

By laboratory experiments it suggested that Less T required within earth than lab.

(2)Bacterial Activity

Decomposition of OM: Methane produced, through process fermentation

Bacteria produce methane, considered as agency in the formation of other petroleum Hydrocarbons.

Types of Bacteria

Aerobic: requires free O2

Anaerobic: requires combine O2

Faculative: live in presence or absence of O2, can be found in well and helps in , extent unknown.

(3)Catalytic Reaction

 Takes no part in reaction but only accelerates it: same in composition at beginning and at the end.

 May promote the conversion of Kerogen to petroleum at low temperature.

Similarly, Ni, Mo and V like catalysts are also found in Ash/residue from the Petroleum.

(4)Radioactive Bombardment

Heat from radioactive bombardment is also possible source of energy.
Important: uranium, thorium and potassium.

e.g., fatty acid----(alpha)----paraffin hydrocarbon

cyclohexane carboxylic acid----(alpha)-----cyclohexane

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Early Transformation of OM: The Diagenetic Pathway from Organisms to Geochemical Fossil and Kerogen            (Source Rock)

OM, subjected to various degree of microbial and chemical actions: as a result its composition largely changed (during sedimentation process or after sedimentation within young sediments)

By comparison, 20% of OM recoverable, rest is lost; due to degradation in nutrients, then polycondensation to form kerogen at the end

Kerogen is the main source of petroleum (by geochemists)

The whole process is known as or referred to as diagenesis: leads to biopolymers synthesized by living organisms to geopolymers (Kerogen) through fractionation.

> Diagensis: the partial destruction and rearrangement of building stones.

Diagensis can be further divided into:

Biochemical Degradation

Polycondensation

Insolubilization

1 Biochemical Degradation

As we know there are four constituents of recent sediment deposited as source of OM (i. water, ii. organic matter, iii. minerals, iv. microbial organisms: shallow depths)

> Biochemical degradation is divided into:

a). Microbial Activity:

Bacteria + Fungi; present in variety of places (water, soil and in sed).

They would decomposed OM: build up their cells: aerobic and anaerobic (with and without O2).

OM compound dissolve through enzymatic process by organism; then take for their synthesis in their molecule.

Protein + Carbohydrate          (hydrolysed)    Amino Acid +

Surgars

Lipid + Lignins           less active

> In oxidizing; all OM destroyed

In fine grain sediments:

Dissolve oxygen used in pore spaces

Established anaerobic condition: under which, OM—partly decomposed by fermentation (in which sulphates reduced to S, Iron to Fe)

Fermentation: oxidized form of OM e.g., Cellulose   Methane + CO2

b) Free or Hydrolyzable Organic Matter

Sugar and protein: degraded can be found in addition to fatty acid + H/C (Methane): this amount is quite low

About 75-90% OM not destroyed and called as “humin” or “humic acid”

> Up to certain level most of the hydrolysable and free compounds disappeared.

2 Polycondensation

Remaining “humic acid” (residue left from micro-organism) incorporated into new polymeric insoluble structures (humic compounds)

Humic acid; results from the polycondensation of Organic residue of microbial metabolism (more or less oxidizing condition)

Oxidative condensation of Phenol is important process: addition of nitrogenous compound--- occur---through random polymerization-- -of free radicle like semiquinone

Soil humic acid structure (swaim, 1963): polycondensates made of nuclei bearing reactive groups; connected by bridges

a) nuclei: simple/or condensed aromatic/naphtenic

b) bridges: oxygen, sulphur, peptide or methylene bonds

Important reactive group is OH

3 Insolubilization

Decomposition + Polycondensation: first few meters of sediments; which represents 90% of total organic matter in young sediments

With increase in depth fulvic + humic acid converted into humin (insoluble)

Insolubilization occurs during diagenesis on a wider scale w.r.t time and depth (greater time and greater depth w.r.t other two steps)

Two stages: 1st Initial Stage

 First 10m: humic acid fraction

Shows loss of peptide bonds

Decrease of hydrolyzable nitrogen and N/C ratio: elimination of N from solid organic phase (expulsion of N): thus amonia increases in pore water

Result: during same interval: carboxylic and aliphatic group increases

2nd Step  10m-100m

Over this interval: oxygen content reduced

O/C ratio ranges from 0.3-0.6 in young humic acid sediments to

1-0.2 in kerogen: related to elimination of carboxylic acid group.

Source Rock:

“sedimentary rock in which organic material under pressure, heat and time is transferred into liquid/gas hydrocarbons” usually shales and limestone.

Result and Sumary of Diagenesis

OM present within water and sediments degraded by organisms and used in metabolism.

Even in fine mud, part of OM has been consumed

Other part used in constituents of organism cell and enter to biological cycle. The OM lost is about 15-50% of Original by decay

The residue left polymerized or condensed into new form insoluble kerogen. This reaction takes place under mild T and P

Besides kerogen, OM still comparises at the end of diagenesis a minor amount of free hydrocarbons and related compounds, which are synthesized by organism and incorporated into sediments with no or little change, called as geochemical fossils (witnessing the depositional environment).