makogon gas hydrates - 2010

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Review article

Natural gas hydrates A promising source of energy

Yuri F. Makogon*

Texas A&M University, Petroleum Engineering, 3116-TAMU-721 Richardson Building, College Station, TX 77843, United States

a r t i c l e i n f o

Article history:

Received 30 November 2009

Received in revised form

11 December 2009

Accepted 12 December 2009

Available online 21 February 2010

Keywords:

Gas hydrates

Energy source

Messoyacha field

Hydrate distribution

Hydrate kinetics

Morphology of gas hydrates

a b s t r a c t

Gas hydrates are clathrate physical compounds, in which the molecules of gas are occluded in crystalline

cells, consisting of water molecules retained by the energy of hydrogen bonds. All gases can form

hydrates under different pressures and temperatures. The crystalline structure of solid gas hydrate

crystals has a strong dependence on gas composition, pressure, and temperature. Presently, threecrystalline structures are known (Sloan, 1990, 2007) to form at moderate pressure, and nearly ten

structures in the pressure range above 100 MPa. For example, methane hydrate can be stable at a pres-

sure of 20 nPa to 2 GPa, and at temperatures changing from 70 to 350 K (Makogon, 1997). Formation of

gas hydrate occurs when water and natural gas are present at a low temperature and a high pressure.

Such conditions often exist in oil and gas wells, and pipeline equipment.

Hydrate plugs can damage gas transport system equipment. The petroleum industry spends about one

billion US dollars a year to prevent hydrate formation in wells, pipelines and equipment. Natural deposits

of gas hydrates also exist on Earth in colder regions, such as permafrost, or sea bottom areas. Natural gas

hydrates are an unconventional energy resource. Potential reserves of gas in hydrated posits distributed

offshore and on land are over 1.5 1016 m3 (Makogon, 1982). About 97% of natural gas hydrates have

been located offshore, and only 3% on land.

At present time, there are several successful federal research programs in a number of countries for

research and development of gas hydrate deposits. Over 230 gas hydrate deposits were discovered, over

a hundred wells drilled, and kilometers of cores studied. Gas hydrate resource is distributed conveniently

for development by most every country. Effective tools for the recovery of gas from hydrate deposits, and

new technology for development of gas hydrate deposits are being developed. There is a commercialproduction of natural gas from hydrates in Siberia. Researchers continue to study the properties of

natural gas hydrates at reservoir conditions, and develop new technologies for exploration and

production of gas from hydrate deposits in different geological formations.

2009 Published by Elsevier B.V.

1. Introduction

A huge potential resource of hydrated gas, estimated at over

151012 toe, exists on our planet. If we will produce only 17 to 20%

of this resource, it can be a sufficient supply of energy for 200 years.

Gas hydrate deposits exist on land in the polar region, and offshore

around the globe. Over 230 Gas Hydrate Deposits (GHD) have been

found. A map of the discovered GHD is shown inFig. 1.

1.1. A brief history of the discovery of natural gas hydrates

Gas hydrates were first obtained by Joseph Priestley in 1778,

while in his laboratory, bubbling SO2 through 0 C water at

atmospheric pressure, and low room temperature (Priestley, 1778).

However, when describing the crystals he obtained, he did not

name them hydrates. About 33 years later, in 1811, similar crystals

of aqueous chlorine were named hydrates of gas by Humphrey

Davy. Some scientists consider Davy to be the discoverer of gas

hydrates; however, Priestley was the first to create gas hydrates in

the laboratory. The results by Davy did not draw the attention of

contemporaries, and studies of hydrates did not seriously develop

for almost a century. Within the first period of purely academic

studies of gas hydrates from 1778 to 1934, only 56 papers from 16

authors were published. There was not much interest in gas

hydrates from the industry prior to the 1930s.

The second period of gas hydrates study began in 1934, when

Hammerschmidt published the results of the inspection of the

U.S. gas pipelines. It was noted that the inspection was compli-

cated by the formation of solid plugs in the winter time. It was

assumed that they encountered ice plugs due to the freezing of

liquid water and condensed water. Hammerschmidt (1934),* Tel.: 1 979 845 4066.

E-mail address:[email protected]

Contents lists available atScienceDirect

Journal of Natural Gas Science and Engineering

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j n g s e

1875-5100/$ see front matter 2009 Published by Elsevier B.V.

doi:10.1016/j.jngse.2009.12.004

Journal of Natural Gas Science and Engineering 2 (2010) 4959


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relying on his laboratory investigations, showed that the solid

plugs consisted not of ice, but of hydrate from the transported

gas. The urgency with which gas hydrates were studied grew

sharply. It was necessary to investigate in detail the conditions of

the formation of gas hydrates, and to find an effective means of

preventing solid hydrate plugs from forming in pipelines. In the

mid-thirties of the last century,Nikitin (1936)hypothesized that

gas hydrates were clathrate compounds. A few years later, Von

Stackelberg (19491954) confirmed this experimentally. There

were 144 papers on gas hydrates published between 1934 and1965. The third period in the history of studying gas hydrates is

tied to the discovery of natural gas hydrates, which become an

unconventional source of energy in the coming decades. The

existence of gas hydrates in nature was proven in the 1960s

(Makogon, 1965, 1966). Over 9000 papers on natural gas hydrates

have been published over the past forty-plus years. Now we

know that gas hydrates exist in nature, and they are present both

on our planet, and in the universe. Hydrates played an important

role during the formation of planets, and the atmosphere and

hydrosphere of Earth.

The problem of development and production of gas from GHD is

an important problem for the twenty first century. A number of

countries, including the USA, Japan, India, China, Korea, and

Germany, have national programs for studying hydrates, and

industrial production of natural gas from hydrates. Furthermore, inmany other countries, including Russia, Canada, and England,

important studies of gas hydrates are conducted in many labora-

tories. However, even the basic review of publications on gas

hydrates shows that most of the research projects are conducted

separately, at different scientific levels, and the published results

frequently are unnoticed by the energy industry. The scientific

community should be more focused on an effort to improve the

technologies necessary to locate, measure, and produce gas from

gas hydrate deposits.

The first example of natural gas production from hydrates came

from Siberia. The Markhinskaya well drilled in 1963, in the north-

western part of Yakutia to a depth of 1830 m, revealed a section of

rocks at 0 C temperature at a depth of 1450 m, and permafrost

which ended at approximately 1400 m. The conditions of rock

formations matched those of hydrate formation. This match led me

to hypothesize the possibility of finding gas hydrate accumulations

in cold layers (Makogon, 1965). The natural hydrate hypothesis was

seriously doubted by the experts. The idea needed an experimental

confirmation. Hydrates of natural gas were then formed in a porous

medium, and in core samples at the Gubkin Institute of Oil and Gas

in Moscow (Makogon, 1966).

The results have shown the possibility of formation and stableexistence of naturally occurring gas hydrates in rocks, and were

recorded as a scientific discovery of natural gas hydrates. After

a comprehensive international examination, the discovery of

natural hydrateswas recordedin the USSR State Registerof scientific

discoveries asN 75 with the following statement: The previously

unknown property of natural gases to form deposit in the solid

gas hydrate state in the Earths crust at specific thermodynamic

conditions was experimentally established (Moscow, 1969).

Soon thereafter, a group of young geologists named Mark Sapir,

Alexandr Benyaminovich and Anatoly Beznosikov (1970) found the

first gas hydrate deposit in the Messoyakha field in the Transarctic

region on the eastern border of West Siberia. Comprehensive

geophysical and thermodynamic studies performed in the Mes-

soyakha wells showed that gas in a hydrated state exists in the

upper part of the deposit. The underlying part of the deposit con-tained gas in a free state. The Messoyakha field, with original

reserves of about 30 billion m3, was dwarfed by the giant Urengoy,

Yamburg and Medvezhye gas fields in Siberia. However, the Mes-

soyakha production of gas from hydrates was a catalyst in the

growth of research on natural gas hydrates. The field provided gas

to an important metallurgy factory in the Transarctic, and allowed

the factory to replace costly imported coal with the clean, cheap

natural gas. The Messoyakha field was the first confirmation of the

presence of gas hydrate deposits, and introduced the possibility of

their commercial development. The discovery of natural gas

hydrates coincided with the peak of an energy crisis. Studying gas

hydrates became more important as energy prices increased in the

Fig. 1. Distribution of discovered gas hydrate deposits. BSR deposit located by seismic refraction.

Y.F. Makogon / Journal of Natural Gas Science and Engineering 2 (2010) 495950


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1970s. The basic stages of gas hydrate discovery and subsequent

development are as follows:

1778 Priestley obtained SO2 hydrate in the laboratory.

1811 Davy obtained Cl2 hydrate in a laboratory and called it

a hydrate.

1934 Hammerschmidt studied gas hydrates in industry.

1965 Makogon showed that natural gas hydrates exist and

represent an energy resource.1969 Official registration of scientific Discovery of Natural Gas-

Hydrates (24 Dec. 1969)

1969 Start of gas production from the Messoyakha gas hydrate

deposit in Siberia (Dec. 24).

1.2. Characteristics and morphology of gas hydrates

Gas hydrates may formally be referred to as chemical

compounds, because they have a fixed composition at a certain

pressure and temperature. However, hydrates are compounds of

a molecular type. They form as a result of the Van der Waals

attraction between the molecules. Covalent bonds are absent in the

gas hydrates, because no pairing of valence electrons and no spatial

redistribution of electron cloud density occurs during their

formation. Gas hydrates can be stable over a wide range of pres-

sures and temperatures (Fig. 2).

Fig. 3 shows the cell of methane hydrate in structure I. A few

structures exist at pressures above 1000 bar.

Hydrates of gases are widespread in nature, and easily form

during systems (equipment) of production, transportation, and the

processing of gases and a number of volatile liquids. Gas hydrate is

a mineral of the clathratehydrate group.Hydrates have sixdifferent

forms: (1) Molecular sieves, characterized by interconnected

trough cavities and/or passages; (2) Channel complexes when

hydrate forming molecules form a crystalline lattice with tubular

cavities; (3) Layered complexes which form clathrates with inter-

laced molecular layers; (4) Complexes which form with large

molecules having concavities, or niches in which an inclusionmolecule resides; (5) Linear polymeric complexes form by tube

like-shaped clathrate molecules; (6) Clathrates form in cases when

inclusion molecules fill in the closed cavities, creating a shape

similar to a sphere. Hydrates of gases and volatile liquids are related

to the latter type of clathrates.

Four conditions must be met simultaneously, and within one

region in order for the gas hydrate to form: presence of gas, water,

high pressure and low temperature. Pressure and temperature

conditions for some gases known to form hydrates are shown in

Fig. 4. The hydrate formation process is exothermal.

Several properties of gas hydrates are unique. For example, 1 m3

of water may tie up 207 m3 of methane to form 1.26 m3 of solid

hydrate; whereas without gas, 1 m3 of water freezes to form

1.09 m3 of ice. One volume of methane hydrate at a pressure of 26

bar, and temperature of 0 C contains 164 volumes of gas. In

hydrate, 80% (by volume) is occupied by water, and 20% by gas.

Thus, a volume of 0.2 m3 of hydrate contains 164 m3 of gas. The

dissociation of hydrate by increasing the temperature in a constant

volume will be accompanied by a substantial increase in pressure.

For methane hydrate formed at a pressure of 26 bar and temper-ature of a 0 C, it is possible to obtain a pressure increase of up to

1600 bars. Hydrate density depends on its composition, pressure

and temperature. Depending on the composition of gas, pressure,

1

10

100

1000

10000

-25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60

Temperature, C

Pressu

re,

Mpa

Gas-Hydrate-Ice

Gas-Hydrate-Water

Gas-WaterGas-Hydrate-Ice

AB

C

D

E

F

G

Gas-Ice

Fig. 2. Pressuretemperature equilibrium curves for methanewater system for hydrate formation. Presently, only three structures are known at moderate pressure: namely, the

structures I and II (Stackelberg, 19491954;Davidson, 1983), and structure H (Ripmeester et al., 1994).

Fig. 3. Cell of MethaneHydrate Str. I, (T. Y. Makogon, PersonalCommunication,2002).

Y.F. Makogon / Journal of Natural Gas Science and Engineering 2 (2010) 4959 51


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and temperature, the density of hydrate changes from 0.8 to

1.2 g cm3. Density of some gas hydrates is reported inTable 2at

equilibrium pressure, and a temperature of 273 K. However, density

of hydrates changes depending on pressure and temperature, as

shown in Table 2 and Fig. 5. Composition of gas hydrates also

strongly depends on free gas composition, pressure, and temper-

ature (Tables 1 and 3).

The morphology of gas hydrate crystals depends on water and

gas compositions, pressure, temperature, and the phase state of

water (liquid, vapor or solid) and gas. More than ten thousand

different forms of crystals were studied. Nuclei of hydrate crystals

usually start to form at a gas-water interface, and grow to a total

coverage of the interface (grow to totally cover the interface?).

Following that, crystals grow in free gas phase or in water. There are

three basic morphologic forms of hydrate crystals: massive, whis-kery and gel-like, as shown in Fig. 6-a through d (Figs. 7 and 8).

2. Natural gas hydrates hydrates formed in nature

Natural gas hydrates are metastable minerals, where the

formation and dissociation depend on the pressure and tempera-

ture, composition of gas, salinity of the reservoir water, and the

characteristics of the porous medium in which they were formed.

Hydrate crystals in reservoir rocks can be dispersed in the pore

space without the destruction of pores; however, in some cases, the

rock is affected. Hydrates can be in the form of small nodules (up to

12 cm in size), in the formof small lenses, or in the form oflayers up

to several meters thick (Fig. 9).

Gas hydrates may have also formed in space, and helped to form

planets of the solar system, as well as the hydrosphere and atmo-sphere of Earth. In order to release gas from a gas hydrate deposit,

one has to heat the entire mass of rock containing the gas hydrate.

The amount of energy required will depend on the heat capacity of

the hydrate, the heat capacity of the hydrate-saturated rock, the

specific concentration of hydrate in the rock pores, and the degree

of supercooling, which caused the formation of the gas hydrate

deposit. Hydrates possess a high acoustic conductivity and low

electrical conductivity (Makogon, 1966), which are used for the

effective methods of finding and evaluating a gas-hydrate deposit.

Dissociation of hydrate in rock, especially at offshore conditions,

can be accompanied by a significant change in strength of hydrate-

bearing rocks cemented by gas hydrates.

2.1. The location of gas hydrate zones

The mechanism of how gas hydrate deposits are formed and

where hydrates are located has been affected by numerous factors,

such as thermodynamic conditions in the region; the intensity of

generation and migration of hydrocarbons; the composition of gas;

degree of gas saturation and salinity of reservoir water; structure of

porous medium; lithology of reservoir; geothermal gradients in the

zone of hydrate formation, and in the basement rocks; and by the

phase state of hydrate formers. The Hydrate Formation Zone (HFZ)

represents the thickness of sediments in which the pressure and

temperature correspond to the thermodynamic conditions of stably

existent hydrate. These HFZs arefound where the earth is cold, such

as the Arctic (Fig. 10) and at the bottom of oceans (Fig. 11).

With an increase in the salinity of water, the thickness of theHFZ decreases. The thickness and the temperature of the HFZ in the

offshore strongly depend on the sea bottom temperatures, and

temperature gradient in the sediments. With an increase in sea

bottom temperatures, the size of the HFZ decreases. In the regions

with permafrost, the thickness of sediment in which gas hydrate

deposits exist can reach 400 to 800 m. The HFZ in the ocean is

found in the deep-water shelf and the oceanic slope at depths of

200 m, or deeper for the conditions of polar oceans, and from 500

to 700 m or deeper for the equatorial regions. The upper boundary

of the HFZ offshore is located near the seafloor.

Permeability of hydrate-saturated deposits is very low. If

hydrate saturation of pore space is over 20 to 25%, then the rocks

Temperature,

Pressure

atm

0

100

200

300

400

500

600

700

800

900

1000

0 5 10 15 20 25 30 35

CO2CH4

H2S

C3H8

Nat.Gas

Fig. 4. Equilibrium PT hydrate formation for different gases.

0.88

0.9

0.92

0.94

0.96

0.98

1

1.02

1.04

1.06

1.08

10 1000

Pressure, atm

100

H2S

Orenburg

Shebelinka

CH4

Density,g

/cm

3

Fig. 5. Relationship between the density of gas hydrates and equilibrium pressure.

Table 1Heat of dissociation of gas hydrates.

Gas Formula Dens ity g/cm3 Mole volume

cm3/mol

Heat of dissociation

T>0 C T


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can be considered impermeable. Resistivity and sonic velocity of

hydrate-saturated layers is very high. These characteristics can be

used for the discovery of gas-hydrate deposits.

2.2. Characteristics of gas hydrate deposits (GHD)

There are two basic forms of GHD: primary and secondary. A

primary deposit is one which does not melt after its formation.Primary deposits are usually found in deep water, where temper-

atures do not change rapidly over time. They are formed by the

gases dissolved in the reservoir water, and are located in the near

seafloor sediments, characterized by high porosity, low tempera-

ture, and low rock strength. Frequently, a primary GHD does not

have good barriers or seals. The hydrate begins to form in the pore

space and eventually plugs the migration paths which trap more

hydrate.

The hydrate can also act as cement holding the rock together.

After the decomposition of hydrate, the porous media may revert

back to a permeable, unconsolidated state.

For a primary GHD, the gas can be found over large areas that do

not depend on the presence of structures. Free oil or gas may be

present in the case of primary GHD.

Secondary GHD are usually located in the Arctic onshore. Theyare associated with natural gas reservoirs, located under the

impermeable cap rocks in structural, or stratigraphic traps. Upon

temperature decrease in the formation (lower than the equilibrium

temperature for the existing gas of this composition), hydrates may

form. The temperature of rock layers on the continents is cyclic

during the geologic time. During these cycles, the gas hydrates in

the rocks will form and melt repeatedly. Often, there is a free gas or

oil under the hydrate layers.

An example of this kind of field is the Messoyakha field in

Siberia, which is now in the decomposition stage due to an increase

in temperature. About two thousand years ago, the Messoyakha

was a 100% gas hydrate field, in which there was no gas in the free

state. The layers are warming and some of the gas is now present as

free gas. Thus, GHD areforming and melting over geologic time. The

most promising regions to look for commercial deposits of gas

hydrate are the deep-water shelves, continental slopes, and conti-

nental abyssal trenches, with depths of water ranging from 700 to

2500 m. However, the most promising resources of gas hydrate are

concentrated in only 9 to 12 % of the ocean floor ( Fig. 12).

In many sediments and rocks, the pressure and temperature arefavorable for the formation of gas hydrates. However, in most of the

rocks the saturation of gas hydrate is too low to be commercially

developed. For example, in Messoyakha Field only 40 m of hydrate

has been identified in the HFZ layers that are 600-m thick. This

corresponds to 6.6% of thickness of the HFZ. In the Nankai Trough

(offshore Japan) there are 505 m of overall thickness of the sedi-

mentary rocks in which thermodynamic conditions were favorable

for the formation, and stable existence of GHD. However, only 17 m

of formation contains gas hydrates at reasonable saturations, which

constitutes only 3.4% of the total HFZ thickness. At Blake Ridge (East

Cost of the USA), the hydrate formation zone is 440-m thick.

However, only 7.5 m (i.e., only 1.7% of the thickness of the HFZ)

contains natural gas hydrates. Fig. 13 shows the pressure and

temperature conditions of some GHD located offshore. It is clear

that the majority of the GHD are in the supercooled state; i.e., the

temperature of the hydrate-saturated layers is considerably lower

than equilibrium temperature/pressure. In this case, pressure in

GHD should exceed equilibrium by more than several tens of bars,

and up to over one hundred bars. This does not normally occur in

offshore regions, and greatly increases the reservoir temperature.

It is important to emphasize that geology, thermodynamic

conditions, depth of water and GHD, infrastructure of region, etc.,

can strongly influence and dictate the adequate technology for the

development of GHD. To rapidly improve the technology, the

industry should form an International Coordination Board to help

solve the vital problems associated with the development of GHD.

The board should provide guidance for the acquisition of research

money from different organizations, and for various projects. The

world needs energy concentrated in natural gas hydrates. However,the technology must be developed as soon as possible in order to

produce GHD in the near future.

2.3. Composition of natural gas hydrates

The composition of natural gas hydrates is determined by the

composition of gas and water, and the pressure and temperature at

which they existed during formation. Over geologic time, there will

be changes in the thermodynamic conditions, and the vertical and

lateral migration of gas and water; therefore, the composition of

hydrate can change both due to the absorption of free gas, and the

recrystallization of already-formed hydrates. Based on cores taken

while drilling in GHD, hydrate usually consists of methane with

small ad mixtures of heavier components. However, in a number of

cases, hydrate contains a significant volume of heavy gases (seeTable 3). The presence of heavy hydrocarbons in the hydrates is an

indicator of the presence of oil reservoirs in the formations below

the GHD.

3. Methods of developing gas hydrate deposits

The following properties are useful in exploration for GHD: (1)

high sonic velocity; (2) high electrical resistance; (3) low density;

(4) low thermal conductivity; and (5) low permeability to gas and

to water. One can evaluate GHD by using seismic data, gravimetric

surveys, the measurement of heat and diffusion fluxes above the

GHD, and the measurement of the dynamics of electromagnetic

Table 2

Some properties of gas hydrates.

Gas Molecular

Weight

g/mole

Dissociation

pressure at

t 273 K,

MPa

Lattice

constant,

nm

Specific volume

of water in

hydrate state at

t 273 K, cm3/g

Hydrate

density at

t 273 K,

g/cm3

CH4 16.04 2.56 1.202 1.26 0.910

C2H6 30.07 0.53 1.203 1.285 0.959

C3H8 44.09 0.172 1.740 1.307 0.866

i-C4H10 58.12 0.113 1.744 1.314 0.901CO2 44.01 1.248 1.207 1.28 1.117

H2S 34.08 0.096 1.202 1.26 1.044

N2 28.01 14.3 1.202 0.995

Ar 39.95 8.7 1.202 1.26

Kr 83.8 1.46 1.202 1.26

Xe 131.3 0.156 1.200 1.252

Table 3

Composition of gas of natural gas hydrates (After Taylor, 2002).

Gas hydrate deposit Gas composition, mol %

CH4 C2H6 C3H8 iC4H10 nC4H10 C5 CO2 N2

Haakon Mosby Mud

volcano

99.5 0.1 0.1 0.1 0.1 0.1

Nankai Trough, Japan 99.3 0.63

Bush Hill White 72.1 11.5 13.1 2.4 1 0

Bush Hill Yellow 73.5 11.5 11.6 2 1 0.3 0.1

Green Canyon White 66.5 8.9 15.8 7.2 1.4 0.2

Green Canyon Yellow 69.5 8.6 15.2 5.4 1.2 0

Bush Hill 29.7 15.3 36.6 9.7 4 4.8

Messoyakha, Russia 98.7 0.03 0.5 0.77

Mallik, Canada 99.7 0.03 0.27

Nankai Trough -1, Japan 94.3 2.6 0.57 0.09 0.8 0.24 1. 4

Blake Ridge, USA 99.9 0.02 0.08



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field in the region being investigated. The most common method is

seismic surveying at frequencies of approximately 30 to 120 hertz(1 hertz 1 s1) with a resolution ranging from 12 to 24 m, and

high-frequency over 400600 hertz with a resolution of 12 m.

One can use standard two-dimensional (2D) seismic to locate the

lower boundary of the hydrate-saturated formation by looking for

BottomSeismic Reflectors (BSR). In GHD, BSR areformed by free gas

underneath the hydrate layer. Unfortunately, 2D seismic surveying

does not answer many important questions, and in particular, it

does not provide information about the degree of hydratesaturation.

The results of high-resolution, three-dimensional seismic

surveying are more informative, and make it possible to determine

lower and upper boundaries of the hydrate-saturated layers. It is

necessary to learn how to evaluate the concentration of hydrate in

the rocks, which will make it possible to determine the amount of

Fig. 6. a. Methane hydrate film formed on the free gaswater surface (Makogon, 1960). b. CO2-Sw Hydrate Mono Crystals (Makogon, 2000). c. Secondary black methane hydrate

crystals with transformation of color. d. Secondary black natural gas hydrate crystal formed in water.

Fig. 7. After whiskery crystals of gas hydrate formed erosion of stainless steel.

Fig. 8. Solid gashydrate plug formed in an offshore gas pipeline, diameter 16 in.

(Courtesy of Petrobras).



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gas trapped in GHD.Fig. 14illustrates the seismic profile of a GHD

located in the Caspian Sea. Detailed evaluation of GHD is accom-

plished by combining seismic data with well log, and core data

obtained from wells. However, much more research is required to

perfect these methods.

To eventually produce natural gas economically from GHD, it is

important to determine notonly the potential gas-in-place, but also

what amount can be extracted economically. The effectiveness of

Fig. 9. Cores of natural gas hydrates (Collett, 2000).

Fig. 10. Gas hydrate stable zone onshore (AfterMakogon, 1965). Fig. 11. Gas hydrate stable zone offshore (After Makogon, 1970).



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the extraction is determined by the geological and thermodynamic

conditions, and by the concentration of gas hydrate in the deposit.

To produce the free gas, the hydrate must be first changed from

a solid to a fluid.

Thus, it is necessary to use much of the energy contained in the

GHD for heating the rock layers near the GHD. Preliminary esti-

mates show that the coefficient of extraction of the gas hydrate can

be as high as 50 to 70%. However, from total world potential

resource it has been estimated that the coefficient of extraction

should average from 17 to 20%.

For offshore conditions, with the depths of water ranging from

0.7 to 2.5 km, effective production of gas from GHD in the majority

of the cases may occur when hydrate saturation of porous media

exceeds 30 to 40%. However, each geologic region will have to be

studied in detail to establish the minimal hydrate saturation that is

required. To change GHD to natural gas, it is necessary to (1)

decrease reservoir pressure to lower than equilibrium one; (2)

increase the temperature to higher than equilibrium one; (3) inject

active reagents; which facilitate the decomposition of hydrate; and(4) use some new technology. The easiest method is to lower the

reservoir pressure in GHD. Clearly, this method is only feasible

when free gas is found below the GHD.

3.1. General characteristic of the Messoyakha gas hydrate field

The Messoyakha field was discovered in 1967 in the north-

western portion of East Siberia, in the almost inaccessible region of

the Trans-arctic, on the west side of the Yenisey River. Its coordi-

nates are 68.5 to 68.7 N and 84 to 85 W. The lowest outsidetemperatures reach 55 C in January, while the average for the

month is28 C. The average temperature in July is10C, and the

average annual temperature is 18C. The thickness of the

permafrost in the field ranges from 420 to 480 m. Cross-section of

Messoyakha GHD is presented inFig. 15

The cyclic supercooling of the gas hydrate deposit during

geological time contributed to the active process of formation and

dissociation of hydrates, which led to the destruction of the mineral

cement between the sand particles in the GHD. Thus the productive

layers of the GHD are characterized by low rock strength. The

maximum permissible reduction in pressure cannot exceed 2 to 4

bars, above which formation collapse can occur. Development

began in December 1969, against the background of two giant

Siberian gas fields called Urengoy and Yamburg. However, Mes-

soyakha played the role of catalyst in the development of natural

gas hydrates studies. First of all, it ensured the replacement of

expensive imported coal to the region. Secondly, the field

confirmed the presence of gas hydrate deposits, and the real

possibility of their commercial development.

The Messoyakha structure is 12.519 km on the top of the

Dolganskoy Formation of AlbianCenomanian age with amplitude

of 84 m. The geological section, revealed by deep drilling, is the

sandy argillaceous deposits of Middle Jurassic, and lower and Upper

Carboniferous age, overlapped by Quaternary sediments. The

deposit is located in part of the Dolganskoy formation; the floor of

the gas-bearing capacity is equal to 75 m, and it measures 730 m

from minimum depth to the topof the layer. The depth of gas-water

contact is located at a depth of approximately 850 m. The porosity

varies from 16 to 38% with an average value of 25%. Residual watersaturation varies from 29 to 50%, averaging 40%. The permeability

Fig. 12. Most effective zone for development of GHD.

Fig. 13. Real pressuretemperature conditions for gas hydrate deposits with different gas composition.



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varies over wide limits from several mD to 1D, with a 125 mD

average. Initial reservoir pressure was 78 bar. The initial composi-

tion of the free gas was: C1-98,6%; C2 0,1%; C3 0,1%; CO2 -0,5%;

N2 0,7%. The salinity of reservoir water does not exceed 1.5 %,

which confirms the presence of active dissociation of hydrates in

the deposit.

The initial reserves of gas, without taking into account the

presence of hydrates were 24109 m3. The reserves of gas in the

hydrated state prior to the beginning of field development were

estimated at about 12109 m3.

Fig. 16shows the pressure and temperature in Messoyakha; the

equilibrium curve of gas hydrate under in situ conditions is also

included in this figure.The boundary of phase transition passesover

the conditional interface with a temperature near 10 C. Productive

layersare divided into twodeposits: (1)freegas that is located lower

than equilibrium surface; and (2) gas hydrate, which is located

higher than equilibrium surface. The geothermal gradient (GTG) in

the interval of the frozen layers is around 1 C per 100 m. The GTG

under the permafrost layers is of 3.0C per 100 m. The temperature

atthe top ofthe deposit is8 C,whereas atthe bottomit is12C.The

GTG in the productive part of the deposit is 4.2 C per 100 m.

There is an absence of lithological trap. The thermodynamic

interface of the gas hydrate and free gas deposits does not have

a lithological trap. The hydrate-saturated intervals are located in

the layers where the thermodynamic equilibrium exists, and free

gas is present. As such, conventional oil and gasmethods can be

used to develop the GHD. Hydrate saturation of pore space in the

initial stage was about 20%. The maximum degree of supercooling

in the reservoir prior to the beginning of development did not

exceed 2 C (at the top of the productive layer). The average degree

of supercooling was 1 C. Low supercooling contributed to the

decomposition of hydrate by insignificant lowering in the deposits

reservoir pressure. This prevented the formation of hydrate during

Fig. 14. High resolution seismic cross-section with gas hydrate deposit (After Diaconescu et al., 2001).

Fig. 15. Cross-section of Messoyha Gas-Hydrate Deposit in East Siberia.

Fig. 16. Thermodynamic cross-section of Messoyakha gas-hydrate field. Black area

represents hydrated layer, gray free gas saturated layer.



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the drilling. The composition of the drilling mud, containing

calcium salts, prevented the formation of hydrates.Fig. 17presents

the gas production, and actual and calculated reservoir pressure

during the production and shut-in periods.

On 31 December 2008, the gas production from the Messoyakha

Deposit was 13.3109 m3, of which 6.9109 m3 were produced as

a resultof dissociationof hydrates. There wasa decreasein reservoir

pressure.The reservoir pressure,after 35 years of development, was

reduced from 78 bar to 60 bar. In the absence of hydrate, the reser-

voir pressure should have been 36 bar. In the first years of devel-

opment, with high rates of gas production, the reservoir pressurewas lowered to 50 bar, which was below the equilibrium one by 16

bar. In this case, the active process of decomposition of hydrate

began, and continued for manyyears. After the field had been shut-

in foran extendedperiod (from1979 to1982), thereservoir pressure

increased to 60 bar; i.e., back to equilibrium one. Currently, the gas

production does not exceed 175106 m3 per year, and the reservoir

pressure has remained practically constant. The volumes of the gas

produced from the deposit, approximately corresponded to the

volumes of hydrate gas entering due to dissociationof hydrates. The

position of gas-water contact did not change as gas was produced.

4. Conclusions

The energy concentrated in natural gas hydrates can serve as an

unconventional energy source very important to sustain thegrowing energy needs for several decades. Natural gas hydrates are

more evenly distributed on the planet than sources of hydrocar-

bons. The production of gas from GHD will be accessible to many

countries. Many existing technologies can be used to find and

develop GHD. However, significant Research and Development will

be necessary before GHD can be developed economically. The

economic and ecological aspects of producing a GHD must be

evaluated. Both the economics and the ecological aspects depend

upon developing technologies. In addition, each GHD will be

different, so different technologies may have to be employed.

Experience in Messoyakha field showed that the cost required to

produce the GHD was about 15 to 20% higher than a conventional

gas field in the same area. Expendituresfor drilling wells in GHD are

considerably lower than the cost of drilling wells in natural gas

reservoirs, because GHD are located at shallow depths. A better

formation evaluation technology is needed to better define a GHD

in order to improve the economics of its development. The most

important problem is the creation of highly-effective technologies

of the transfer of natural gas from its solid state into free gas.

Studies of natural gas hydrates must be coordinated on a world-

wide scale which could speed up the technology development.

Acknowledgement

The author is grateful to Professor Academician Dr. Michael J.

Economides for reviewing the manuscript and making some valu-

able suggestions.

References

Collett, T., 2000. Ladd detection of gas hydrate concentration on the Blake RidgeODP. Rep.164.

Davidson, D.W., 1983. Gas hydrates as clathrate ices. In: Cox, J. (Ed.), Natural GasHydrates.

Diaconescu, C.C., Kieckhefer, R.M., Knapp, J.H., 2001. Geophysical evidence for gashydrates. Marine Petroleum Geol. 18.

Hammerschmidt, E.G., 1934. Formation of gas hydrates in natural gs transmissionlines. Ind. Eng. Chem. 26, 851855.

Makogon, Y.F., 1960. Hidtrates of Natural Gases. J. Gas Technik 3, 1041.Makogon, Y.F., 1965. A gas hydrate formation in the gas saturated layers under low

temperature. Gas Indus. 5, 1415.Makogon, Y.F., 1966. Peculiarities of Gas-Field Development in Permafrost. Nedra,

Moscow.Makogon, Y.F., 1982. Perspectives for the development of Gas Hydrate deposits. In:

Fourth Canadian Permafrost Conference, Calgary, March 26, 1981.Makogon, Y.F., 1997. Hydrates of Hydrocarbons. Penn Well, Tulsa, USA, 516 p.Nikitin, B.A., 1936. Gas hydrates. Z. Anorg. Allg. Chem. 227, 81.Priestley, J., 17781780. Versuche und Beobachtungen Uber Verrshiedene Gattun-

gen der Luft, Th. 1-3, 3:359362. Wien-Leipzig.Ripmeester, J., Ratclife, C., Klug, Tse, J., 1994. II-nt. GHC, N-Y.Sloan, E.D., 1990. Clathrate hydrates of natural gases, Sec. Ed. N-Y.Sloan, E.D., Koh, C.A., 2007. Hydrates of Natural Gases, third ed. NY.Taylor, C., 1954. Formation studies of methane hydrates with surfactants. In: 2nd

International Workshop On Methane Hydrates. October 2002, Washington.Von Stackelberg, M., 19491954. Solid gas hydrates. Zeitschrift Elektrochem 58, 104.

Fig. 17. Reservoir pressure during development of Messoyakha GHD.



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Further reading

Makogon, Y.F., 1972. Natural Gases in the Ocean and the Problems of Their Hydrates.In: VNIIEGasprom. Express-Information, No.11, Moscow, p. 43.

Makogon, Y.F., 1974. Hydrate of Natural Gas NEDRA, Moscow, 1981. PennWell, Tulsa,237 p.

Giavarini, Carlo, 2007. Hydrate of Methane. University of La Sapienza, Roma, 192 p.Makogon, Y.F., Trebin, F.A., Trofimuk, A.A., 1971. Finding of a pool of gas in the

hydrate state. Moscow, DAN SSSR 196 (1), 197206.Makogon, Y.F., Holditch, S.A., Makogon, T.Y., 2004. Proven Reserves and Basics for

Development of Gas Hydrate Deposits. AAPG, Vankouver.Makogon, Y.F., Holditch, S.A., Makogon, T.Y., 2005. Development of G-H deposits oil

and gas J Nos. 7.II., and 14.II.Sapir, S.H.,Beniaminovich, A.F.,1973.Messoyakhygashydrate Field. GeolOil Gas 6, 26.

Glossary

Gas Hydrates:Solid clathrate physical compounds, formed by molecules of gas andwater.

Natural Gas Hydrates: Gas Hydrates formed in nature.Kinetics of hydrates: Dynamics of formation and dissociation of gas-hydrate crystals

at different pressures and temperatures.

Prof. Makogon is a world-renowned expert on gas hydrates. He is the author ofScientific Discovery of Natural Gas-Hydrates (1965). He has authored eight mono-graphs, including six books on gas hydrates and over 260 scientific papers. He holds27 patents, and has over 50 years of experience in education and research for the oiland gas industry. Yuri F. Makogon graduated with honors from the KrasnodarTechnical School in 1951 and from the Gubkin Petroleum Institute in Moscow in1956. Dr. Makogon a Member of the Russian Academy of Natural Science (RANS)since 1990. Prof. Makogon served as the first Chairman of the SPE International,Russian section (199193). Dr. Makogon joined Texas A&M University in 1992. Hesheaded the gas-hydrate laboratory of Texas A&M University since 1995. He wasnominated International Distinguished SPE Lecturer for 20022003. He is currentlythe US Section Regional Secretary of the RANS. Dr. Y.F. Makogon received anHonorary Doctorate from the Nikolaev Institute of Inorganic Chemistry RussianAcademy of Science in 2005. His awards include the Gubkin StatePrize in 1989;Lifetime Achievement Award of Honor by the Sixth International Conference on GasHydrates in 2008; and many international Honor Awards.


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