INTRODUCTION
Recently one of the most important goals, determining the development of national
economy, is the rational usage of natural resources and protection of environment from
contamination and depletion. In connection with intensive development of oil industry
and creation of new contamination sources, the actuality of issue of environment
protection has risen sharply.
Daily there are more than 2.5bln. of crude oil produced. During production,
transportation, refining and oil and oil products usage, there is a low of about 50 mln.
tons per year.
Based on wax content of oil and content of light fractions the nature of oil contamination
of earth and its impact strength can be judged. The sulfur content is also important sign
during evaluation of impact of oil on environment. As oil gets more sulfur content the
hazard of hydrogen disulfide and hydrocarbon contamination increases.
Objective: The objective of scientific work is to find easily available waste of local
industry, absorbent for remediation of soil contaminated by oil and oil products. The
perspective direction of research is wastes of rice refining plant - rice hulls.
Urgency of an issue. During development of oilfields the main factors of soils and
landscapes impact are mostly mechanical interruptions and chemical contamination. The
mechanical interruptions of soil covering are noted during exploration, drilling,
construction of process facilities. At that the flora is destroyed, the upper horizons of soil
are destroyed and consolidated. The flora elimination is stimulating the erosion process.
During drilling soil with high salt content is excavated from wells, thus providing
sources of local technogenic secondary salinization.
The mechanical interruptions of poorly grass-covered soils, especially of light grain
composition, promotes activation of ash processes. Even with light interruptions on bare
surface of soil between plants, the zones of soil-blowing are clearly seen, and by the
plants there are specific forms of microlandscape – hillocks of heaping-up.
The oil has adverse impacts to soil and flora. As the soil gets contaminated with oil the
carbon and nitrogen ration in soil sharply increases, which worsens the nitrogen status of
soils and disturbs the root nutrition of plants. Besides, as the oil gets to the surface of
earth and soaks in ground it makes the fertile soil layer to recover for long period of
time. This can be explained by oxygen displacement from ground, which is necessary
for plants and microorganisms’ lives. The soil’s autopurification takes much time due to
biological decomposition of oil.
Novelty of scientific work. The novelty of the scientific work is the implementation of
rice hulls, which is used for biologic decomposition of oil. The rice hull is a
biostimulant. The rice hulls is full with organic materials and it absorbs the oil well. The
composted fertilizer prepared with rice hulls is rich with organic substances.
Kyzylorda region, the place where the biggest part of Kazakhstan rice is grown, annually
there are more than 6.0 thousand of tons of rise hulls produced, which consists of
cellulose for 80%, silicon – 15%, minor elements – 5%.
The rice hulls is multi-tons renewable waste, which until now hasn’t become of common
use.
The hulls, which is organosilicon phytogenous polymer, doesn’t burn, decay, is not good
for stock feed. Due to mentioned causes, as well as availability and low price, the rice
hulls is irreplaceable source of biocompost which is required for oil biodegradation.
Practical value. Being cheap and easily available the rice hulls, renewable multitonnage waste of rice growing. In this connection we see the implementation of rice
hulls as regulator of soil autopurificatoin as efficient and reasonable. For these purposes
two types of products were used – first is the rice hulls mixed with other fillers
(livestock manure, seeds of wild plants, etc.) and the second one is based on the rice
hulls.
CHAPTER I. CURRENT SITUATION OF RECULTIVATION OF OILPRODUCTS
CONTAMINATED SOILS.
Conditions of soil contamination with oil products.
One of the most dangerous substances polluting environment, due to its properties and
wide usage, is oil – the complex aggregate of substances, which consists of almost 3000
components and most of them are oxidizable. That’s why the toxic impact of oil and oil
products on plants and life forms is really wide.
The analysis of problem state of environment pollution during construction of oil and
gas wells shows, that during production of such works a pollution with oil, oil products,
oil gasses and burnt gas, hydrogen disulfide, sulfur oxides, hard waste waters, drilling
fluids and drilling wastes, various SAA (surface acting agent), phenols, aldehyds and
other chemicals, used for stimulation of drilling, can often take place. That is why the
further improvement of activities aimed for protection of environment from pollution is
important. [34].
The large sources of pollution of environment are regional oil production complexes
major pipelines. The pollution of soil, drain and surface waters with oil and its
components, highly mineralized formation and drain waters, slams is also happening
during the stage of oil and gas crude processing for refining. At that the significant
amount of oil components, associated oil gas and its exhausts enters the atmosphere.
[33].
General ecological consequences of oil and gas entering environment result to:
a) modification of soil and surface cover,
b) contamination of surface and ground waters and bottom silts,
c) modification of chemical composition of plants, transformation of plant formation,
d) genera landscape degradation
Soils are considered contaminated with oil and oil products if their concentration reaches
level at which:
There is depression or degradation of plant formation
There is disturbance of ecological balance, disappearance of algal flora, mesofauna
There is change of water-physical properties and structure of soils
There is significant increase of proportion of carbon of oil products in noncarbonate
(organic) carbon element of soils
There decrease of productivity of farming lands
There is elution of oil products from soils to undergournd and surface waters.
The safe level of soils contamination is recommended to consider the level at which
none of the abovementioned consequences, would not arrive due to contamination with
oil products.
The “Normal” level of indices of soil condition, are the levels that enable performing
general soil functions and don’t cause negative impact on adjoining environs (air,
water), plants and human.
Generalizing data of pilot researches in various countries of the world, including
different native zones, the following treshhold levels of concentration of oil products
(table 1).
Table 1 – Classification of levels of oil products soils.
Level of pollution
Background
Low
Moderate
Middle
High
Very High
Total content of oil product in soil.
mg/kg
%
Up to 100-500
Up to 0,01-0,05
500-1000
0,05-0,1
1000-5000
0,1-0,05
5000-10000
0,05-1,0
10000-50000
1,0-5,0,
Above 50000
Above 5,0
The reaction of biogeocenose on soil contamination in various native zones is
determined experimentally. With that it is considered that this reaction is also depending
also from initial load of contaminating agents to the soil. With same level of residual
pollution the ecosystem can recover or not recover depending if it was ‘shock’ pollution,
or it accumulated gradually.
The minimal level of oil products content in soil, above which there is environment
conditions aggravation, can be called the upper safe limit of concentration, or the limit
of permissible concentration (MPC). The MPC of oil products in soils in most of the
country is not set, because it depends on combination of many factors: type, content and
features of soils, climatic conditions, composition of oil products, type of vegetation,
type of land use, etc. These norms should be developed for specific region and specific
type of soils.
In many cases the knowledge of period of self-recovery allows to take reasonable
decision on practicability of carrying out various activities on artificial soil cleanup of
contaminated territory with interruption of upper soil layer, because sometimes the most
advantageous can be the use of natural features of biogeocenose for self-purification in
combination with some features, stimulating the process of self-purification. The
recovery of humus accumulation layer can take dozens and hundreds of years. With that
the soil can lose its features, which allow it to be filter restraining penetration of
impurities to underground waters and their spreading into the depth of the system.
The soils which contain oil products above MPC are subject to detoxification and
recultivation, because without such activities, they don’t come out from the stage of
degradation and will cause stabile negative impact on the environment.
In the Mack Jill’s review [49] there is data from researches of many countries on
defining safe limits of oil and oil products content in soils. This data is completely
different due to climatic and soil features of places where research was done. In general
the upper safe level of oil content in soil is 1000 mg/kg. The stop of plants growth was
observed at placement of about 3500 mg of oil to one kg of soil. As a result of
generalization of world experience and these researches this author composed a table of
approximate norms of oil products content in soils, which are subject to recultivation.
(table 2).
Table 2 – Relative level of soils contamination, containing various amounts of oil.
pollution level
Oil content in soil, mg/kg
Mineral part of soil
Organic part of soil
Light – moderate: some
decrease of plant growth, if no
measures taken – temporary
5000 –20000
decline of soil properties.
Moderate – high: some plants
develop well, during careful
regulation they stay green, the soil
can be recovered during 3 years,
without recultivation the recovery 20000 - 50000
will take 2-3 times more time.
High – very high: the oil soaks
the soil for the depth of 10 sm,
only few plants live, in case of
correct recultivation the soil can
Более 50000
be recovered in 3-5 years, without
it the recovery takes 20 years and
more.
40000 - 150000
150000 - 750000
Более 750000
In Netherlands, Germany there are three levels accepted for evaluation of soils
contamination with chemical substances, including mineral oils, depending on such
levels there is a need determined for specific environment protection activities. As the
initial level for evaluation of pollution of soils there is a system of ‘background levels’
accepted..
They represent regional background of content of toxic elements and substances,
specific for the territory of the country, and numerically represent signal level 1.
Level 2 – this is higher pollution, which requires observation over the dynamic of
pollution and elimination of reason of pollution and it can be considered as the level,
above which the soils are considered ‘dirty’.
At the signal level 3 there is a need for cleaning soils (table 3). According to WCAclassification, carrying out activities of soils cleaning from oil products is provided in
case of oil products concentration of 5g/kg and higher.
Table 3 – Signal levels of oil contents in soils.
Signal level
1
2
3
Oil product content, mg/kg
50
1000
5000
Norms of the Netherlands envisage carrying out activities on cleaning soils from oil
products at concentration fro 5000mg/kg (higher 0.5% on weight basis on dry
substance).
In different countries the level of soil contamination, above which the intensive activities
on detoxification and recultivation is required, falls within the limit of 5000 to 10000
mg/kg. In case of contamination from 1000 to 10000 mg/kg the gentle activities are
required for enforcement of processes of selfpurification: pollution source elimination,
soil loosening, moistening, aeration, etc. It is assumed that in this case the oil products
content will get down to the safe level during a year. At the level of pollution above
10000 mg/kg there is a need to select a best mean of recultivation [49].
In the ‘Guideline on identifying degraded and polluted soils’ [49] the five levels are set
for soils contamination with oil products (table 4).
Table 4 – The levels of oil products' content in soil in accordance with the ‘Guideline on
identifying degraded and polluted soils’
Element,
compound.
Oil and oil
products
Content (mg/kg), correspondent to the level of contamination.
1
2
3
4
5
Admissible Low
Medium High
Very
high
<MPC
From 1000
From
2000
From 3000
>5000
The soil is the biologically active structure, saturated with various microorganisms
(bacterium and fungus). Decomposing organic remainders of soil (including oil
products) such microorganisms promote formation of organic acids, which react with
particles of mineral substances. [34].
The most important part of soil is – humus, which consists of high-molecular organic
acids, salts and other substances. The soil colloids consisting of little organic and
mineral particles provide ion-exchange capacity, acidity and soil buffering. Usually oil
pollution cause significant changes of physicochemical properties of soils. Thus,
destruction of weak soil structures and dispersion of soil articles are accompanied by
decrease of water permeability of soils.
In soil, polluted with oil, the balance between carbon and nitrogen raises sharply, which
interrupts the nitrogen status of soils and root nutrition of plants. Besides, when oil gets
to the surface of land and soaks into soil it intensively pollutes underground waters and
soil, resulting to long recovery of fertile soil layer. This can be explained by the fact that
oxygen is replaced from soil, and it is necessary for lives of plants and microorganisms.
According to data of VNIICGTneft [33], during last 10-15 years together with growth of
oil and gas production the hazardous emission volumes, solid wastes increased as well,
plus areas of disturbed soils.
Below are average volumes of environment contamination with various agents based on
calculation of 1t of prepared oil.
Drainage waters, м3 …………………………………………..0,28
Including:
Provisory clean ………………………………………….. –
Sent to treatment facilities ……………….0,18
Polluted……………………………………………..0,10
Dust, kg ……………………………………………………..0,02
Carbonic oxide, kg ………………………………………….0,43
Hydrocarbons, kg …………………………………………..6,60
Sulfur oxides, kg ……………………………………………0,04
Nitrogen oxides, kg ……………………………………………0,04
Solid wastes, t ………………………………………….0,027
While currently oil producing facilities, as usual, placed to operations together with
treatment facilities, impermeable berms, etc, neither modern equipment, nor improved
technology can fully exclude negative impact to the environment of drilling of wells,
production and transportation of oil. That is why it is important to look for most efficient
technical solutions providing safe environmental conditions for producing and
transportation of oil and gas, prevent emergency spills and process outbreaks of liquid
hydrocarbons from wells, eliminate consequences quickly.
For successful decision of stated issues it is necessary to define the sources of biosphere
pollution with oil, typical changes in native complexes, as well as ecological and
economical consequences. The general picture of oil and gas pollution of environment is
shown at the structural model developed by VNIISPTneft where all the elements of each
level are connected by cause-and-effect relation (diagram 1).
Oilfield
equipment
Drilling rigs
Degradati
on of
landscape
s.
Decreas
e of
initial
producti
vity of
plants.
Decline
of
animals’
lives
conditio
ns.
Decrease of quality
of products of plant
and animal origin.
Worsening of human
health and living
environment.
Loadingunloading
equipment of
ports and ships
Pollution of
land plant cover
Pollution of air pool.
Death of
plant
cover and
soil
organisms
Major pipelines
Loss
of
forag
e
lands
.
Pollution of reservoirs
Decreas
e of О2
content
in water
ecosystem
Decr
ease
of fur
anim
als.
Decrease of production of
fishing, agricultural and
hunting industry.
Decreas
e of
reprodu
ction of
animals.
Decreas
e of fish
and sea
products
.
Decrea
se of
comm
ercial
animal
s.
Damage
of shore
ecosystem.
Decreas
e of
recreatio
nal
value of
waters
and
beaches.
Increase of expenses for
recovery of resources and
improvement of
environment.
Diagram 1. Structural model of oil and gas pollution of environment.
The diagram shown gives evidence that the oil industry has multiple pollution sources,
which provide many-sided impact on the native complexes and inflict significant
ecological and economical damage. The main directions of environment protection from
harmful influence of oil industry is decrease of volume of lands interruption, decrease of
pollution with drain waters, decrease of emissions of sulfur oxides and hydrocarbons to
the lower layers of troposphere during production and treatment of oil, emissions of
nitrogen oxides [33].
During operation of oilfields, transport and refining of oil there are a lot of wastes.
Theirs significant part is represented by oil slam, which is stored and accumulated in
open reservoirs – oil slam pits.
The slam pits are the secondary sources of environment pollution. In this connection
utilization and processing of oil slams – is one of the actual tasks of environment
protection in oil producing regions.
The oil slam is stable oil emulsion. The main part of hydrocarbons of slams is heavy
aromatic and paraffin-naphthene hydrocarbons (31-83%), gums (44-10%) and
asphaltenes (4-14%). The wide range of physical and chemical properties of oil slams,
various conditions of formation and storage determine implementation of following
methods: thermal, physical, chemical, physical-chemical. The mentioned methods have
their advantages and disadvantages. In most cases they are low-technology, expensive
and ecologically inappropriate.
Currently in order to destruct oil products the biological method is used extensively. It is
based on usage of various biological products. The advantage is ecological safety. That
is why the proposed method, which does not require power consumption, equipment,
process facilities and is used directly in the locations of slams storage, is the most
perspective [46].
The company ‘Meisner Grundbau’ developed technology [20] of chemical treatment and
disposal of oil containing wastes (oily slams, acid sludge, oily soils, emulsion slams,
etc).
According to this technology, together with method of disposal of collected oil wastes,
the cleaning and recultivation of polluted areas on which oil wastes were stored is
proposed. Such areas are suggested to use for planting, sites with hard coating for
parking, storage facilities, etc. The product obtained during treatment could be used as
construction material and used for road pavement, foundations, coating material, sumps,
etc. According to the company using this method it is also possible to clean areas of oil
spills, eliminate oil pollutions on beaches, which happen in case of emergencies with
tankers or pipelines [20].
Evaluating the consequences of oil pollution it is hard to say if the landscape would
come back to stable conditions, or degradation will be required. That is why during all
activities associated with elimination of pollution consequences, recovery of disturbed
soils, the main principle should be followed – do not bring more harm to environment
that it already has received after pollution. [49].
Perspective directions of researches on soils recultivation.
Based on review of works on recultivation of soils the most perspective direction is
search of biological methods of cleanup of oil products through oil destruction
microorganisms. In this context the researches can move the following directions:
Search and cultivation of biotic community of microorganisms, which actively oxidize
oil products;
Making compost from wastes of plant and animal origin, which will be used for
recultivation of oil polluted sources of land;
Making special mix of compost, mineral mixture and seeds from community of wild
grasses, in order to use them as bio-stimulators and bio-products for degradation of oil
products. \
Implementation of special mix to the oil polluted areas and monitoring of the process of
recultivation of soils and growing, recovery of vegetation.
Biological composting of oil products by microorganisms and recovery of plant
formation of soil.
The higher-priority direction of researches from among abovementioned is forming of
biostimulators and bio products on basis of compost. Procurement of biocomposts can
easily be organized on basis of multi-tonnage renewable wastes of plant origin, such as
rice hulls.
Kyzylorda region, the place where the biggest part of Kazakhstan rice is grown, annually
there are more than 6.0 thousand of tons of rise hulls produced, which consists of
cellulose for 80%, silicon – 15%, minor elements – 5%.
The rice hulls is multi-tonnage renewable waste, which until now hasn’t become of
common use.
The hulls, which is organosilicon phytogenous polymer, doesn’t burn, decay, is not good
for stock feed. Due to mentioned causes, as well as availability and low price, the rice
hulls is irreplaceable source of biocompost which is required for oil biodegradation.
CHAPTER II. CHARACTERISTICS OF EXAMINED OBJECTS AND RESEARCH
TECHNIQUE.
2.1 Physical-chemical characteristics of oil from Kumkol oilfield.
The oil from Kumkol o/f is falls into category of paraffin base oils, and he most difficult
features during substantiation of degassed oil characteristics were chilling point and
weight content of high-polymeric paraffin. The interval rate of such parameters at the
research objects is high and it is hard to find explanation for that. The association of
these parameters with hypsographical location of wells which provided samples could
not be found.
They describe the oil of Kumkol o/f as light, paraffin base, tarry, low sulfur oil. (table1).
Table 1 – Physical and chemical properties and fraction composition of degassed oil.
Title
Density, kg/m3
Viscosity, mPa-s, at 200С
at 50 0С
Chilling point\, 0С
Paraffin saturation point, 0С
Range of
measurement
806,0-857,5
5,86-25,05
2,19-7,77
3-23
Average number
823,8
11,024,02
11,6
47,8
44-52,7
Weight content, % weight of
sulfur, paraffins. \
Volume recovery, %.:
up to 1000С
to 2000
to 3000С
0,06-0,39
3,59-14,15
6,9-19,76
0,136
9,15
8,86
0-11
16-383
6-60
4,5
25,73
45,7
CHAPTER III. RESEARCHES ON RECULTIVATION OF POLLUTIED SOILS.
3.1. Recultivation works required at the oilfield of Kumkol.
Up to present moment the soil recultivation at Kumkol o/f was bound to solely technical
stage – grading the soil surface. The biological stage wasn’t use at all.
The optimum solution of the problem of industrial wastes at Kumkol oilfield is
construction of polygon, where the composting of wastes will take place.\
The wastes neutralization can be done on two directions:
Thermal
Biological degradation.
The wastes burning should be done on the unit of wastes burning, approximately,
according to calculations of ‘Golcler Associates Ltd.’ the expenses for purchase of such
unit, its transportation and operation during a year would be 1.29 mln. US dollars.
The biological degradation is more perspective due to its low price and almost 100%
utilization of final products.
For decomposition of contaminants single strains of organisms can be used as active
agent, micro-bacterial communities, mono and mixed cultures of yeast, fungus and
bacteria. The unique feature of bio-technologies is compulsive aeration and application
of nutrients, stimulating activity of micro-organisms. At various methods of clean up
and content of hydrocarbons in the soil the clean up of soil polluted by oil products will
take 12-18 months.
The treatment of recultivated areas and cover of crops for Kumkol o/f is necessary to be
carried out zone recommendations on agricultural technology for erosion-dangerous
lands:
- in case of area disturbance of sand up to 4-Ha the simultaneous planting of bushes
(dzhuzgun, teresken) and seeding of giant rye grass;
- on flat air cleaning sand, clay sand, salty plains the planting of tamarisk, dzhuzgan,
black saksaul etc is reasonable.
In order to recover disturbed lands on Kumkol o/f it is necessary to develop detailed
project of recultivation in accordance with ‘Directions on development of project of
recultivation of disturbed lands in the RoK’, the work projects of recultivation of
disturbed soils should consist of the following:
Studies’ materials;
feasibility indices of the project;
explanatory note with substantiation of process and design solutions as well as
calculations on work volumes;
cost estimate part;
drawings;
the documents for approval of design solutions are attached to the explanatory notes.
A range of technical and process events to be envisaged for Kumkol o/f in order to
improve conditions of environment. Primarily that is:
construction of unit on gathering and utilization of wastes;
construction of treatment sewage facilities.
Capsulation of gathering systems, separation, treatment and transportation treatments as
well;
Automatic switch-off of wells in case of emergencies by cut plates.
Bunding of wellhead with earthworks in case of oil spill.
In order to prevent spill to landscape provide maximum formation and process water for
injection to formation.
In case of oil spill to the surface dispose it to special pits with further implementation in
process.
Implementation of pneumatics for moving of drilling rigs.
Laying of pipelines underground on the depth of 1.2-1.8meters.
In order to decrease negative impact on soils during their pollution with oil and its
products, the earthing should be done, as well as qualitative technical and biological
recultivation of polluted soils. During all types of activities the following should be
done:
Removal of fertile layer of soil before start of construction work and temporary storing,
piling, conservation and saving fertile layer of soil in order to return it to previous
location.
Carrying out technical stage of recultivation of disturbed lands after end of construction
works, which envisage lands treatment for further proper use in agriculture.
Carrying out biological stage of soils recultivations, providing agronomical, revegetation
and biotechnical activities, aimed on increase of productivity of recultivated soils.
Treating the oil polluted soil with nitrogen and fluorine containing compounds, which
weakens toxic features of oil to the soil and enforces biochemical process of oil
hydrocarbons oxidizing.
Emulsification of oil by means of detergent, promoting activation and habitability of
microorganisms, which participate in bio-decomposition of oil
Rational technology of treatment of polluted areas in order to improve oxidizing
properties.
3.2. Evaluation of soil pollution on Kumkol o/f.
In order to determine impact of oil industry to soil ecosystems first were considering the
existing criteria of soil impact.
1. Based on temporary guidelines on developing section ‘Evaluation of impact on
environment’ the following criteria of technogenic impact on soils:
Insignificant – local chemical pollution with hydrocarbons or associated substances as a
result of production and initial treatment process of oil and gas in limits insignificantly
affecting soil-agrochemical process, or light mechanical disturbance, expressed by
insignificant compression of surface soil horizon, weak and local indication of erosion
process. The general morphological and biological properties of soils are not disturbed.
Moderate – chemical pollution by hydrocarbons or associated substances, formed
as a result of production and initial treatment of oil and gas. This causes partial death of
biota, change of product quality, accumulation of bituminous materials, light change of
secondary chemical processes, strengthening of glygenesis of hydromorphous soils, or
mechanical disturbance expressed by destruction on whole soil profile, peeling-off of
grass sod, outwash of upper or deflation of soils horizons (without formation of new
landscape forms). The soils feature to self-recovery after stop of technogenic
interference is kept, the fragmentary disturbance of soil difference is observed.
Significant – chemical pollution with hydrocarbons or associated substances forming as
a result of process of production of oil, causing bituminisation of soils and grounds,
change of oxidation-reduction conditions, forming of extensive severe pollution halos,
alkalization of soil, soils secondary alcalination, death of biota, forming of
hydrosulphuric forms of glegenesis of hydromorphous soils. The destruction of soil
layer and forming of new landscape forms (ravines, scours, small blow-out pits). There
is tendency forming to spread erosion on nearby areas.
2. The guidelines on evaluation of environment impact of products and materials
located in storages, and stored in the open, provide the following evaluations of
ecological condition of soils: (table1).
Table 1 – Soil condition evaluation
Parameters
Ecological conditions of environment
Permissible
Relatively
satisfactory
Danger
ous
Critical
(extreme)
А. Physical parameters.
More than
20
In practical terms absent
B. Chemical parameters.
1. Increase of content of
water-soluble salts,
g/100g of soil, in layer
0-30 sm.
2 excess of MAC 3В
-1 class of danger
-2 class of danger
-3 class of danger
3 Summary index of
pollution ∑с
C. Biological
parameters
1 Decrease of level of
germ mass.
Catastrop
hic
Up to
10
10-20
0,1
0,1-0,4
0,4-0,8
Above 0,8
until 1
until 1
until 1
1-2
1-5
1-10
2-3
5-10
10-20
Above 3
Above 10
Above 20
below 16
6-32
2-128
Above128
Above
100
Until 5
5-50
50-100
3. According to the ‘Instruction of environment protection during construction of wells
inland on multicomponent hydrocarbon fields, including sour’ there is characteristics of
level of polluting areas on oilfields. The arrangement of polluted areas during the
activity of oil production industries.
Table 2 – Characteristics of contamination level of oil production industries areas.
Pollution
level
Source of
disturbance
Washing fluids
using for
drilling.
Washing
fluids,
condensate.
Residual
compound
Up to 1% of
bituminous
substances.
Up to 2,5% of
bituminous
substances.
Ecological effect
Strong
Washing
fluids, oil
Partial plant
extinction
Very
strong
Emergency
situation with
spill to the
surface of
high-salt
waters and oil.
sulphatechloride
salinification
(solid residue
1%).
Bituminous
substances up
to 3.7%
Significant
sulphatechloride
salinification
(solid residue
1%)
Bituminous
substances up
to 5%
Light
Medium
Projected cover
70% (in case of
natural growing)
Reduced plants
(indicators of
salinification)
Full plant
extinction.
External
displays
-
Whitebrown
stains
appear.
Oil stains
are seen
Oil spills
on the
surface of
soil.
4. According to the ‘Temporary guideline of damage calculation during pollution
of environment, land and water resources by oil products’ the evaluation of soil
pollution by chemicals is carried out according to summary index of pollution (∑с)
(table 3).
Table 3 – Extent of soils pollution
Soil pollution level
Value of index (∑с).
<2
2-8
8-32
36-64
>64
The index ∑с is defined according to the formula:
Permissible
Weak
Middle
Strong
Very strong
∑с =Ci (act)/ Ci (bgrnd)
where: Ci (act)- actual content of 1st toxicant in the soil;
Ci (bgrnd) – index of regional-background content of 1st toxicant in soil, accepted
according to the table 4.
Table 4 – Background content of gross forms of heavy metals in soils (mg/kg).
Soils
Soddy-forest,
sand and
sabulous
sod-podzol,
podsolic, loamy
and clay soil.
Zn
Cd
Pb
Hg
Cu
28
0,05
6
0,05
8
45
0,12
15
0,10
15
Due to unavailability of MAC of oil in this work the background content in the soils is
accepted as 0.1mg/kg. During research on Kumkol, East Kumkol o/f the evaluation of
soils pollution is performed on summary index of pollution.
The factors of degradation of soil-vegetation layer of Kumkol o/f are:
Mechanical disturbance of land cover: drilling and assembly works, operation of wells,
construction of roads, power lines, oil transportation facilities, heaters, accumulation
units, gas pipelines, flares, oil pits, etc. Near with wells the plant cover is almost fully
destroyed in radius of 50-150 meters, further there are rarefied plant communities, old
and downtrodden.
On the first stages of oilfield development the land cover primarily was exposed to
mechanical disturbance during construction of mentioned facilities, and due to that it
was either destroyed completely or disturbed highly.
During construction of roads on the field (the central road from north to south, and roads
in west and east directions) beside delivered ground the upper layer of soils was used,
removed from left and right of constructed road, the plants were completely destroyed.
In period of construction-drilling works the upper part of plant profile was exposed to
significant changes, the soils were compressed, water-physical features go worse
(aeration and water permeability). The technogenic components came into soil mass,
with the leading role belonging to silicate-carbonate drilling fluid.
The following forming of plant cover in bounds of drilling sites during further operation
and carrying out mechanical recultivation went uneven. On the embankments there is
plant cover, with pioneer types of ebelek, spearwort, saltwort. On the leveled areas there
are rarefied communities with different types of plant.
The plants are undersized, which is associated primarily negative conditions of site (the
soils are disturbed, their water-physical features disrupted, technogenic pollutants are
present)
During removal of mechanical impact on soil-vegetation over their reaction will be
different. The vegetation due to its adaptability to severe conditions of deserts would
recover faster, and in soils due to low intensity and short time of active soil forming
process, the disturbances will be present for longer time.
Currently nearby the oil wells the mechanical recultivation was carried out, but the
process of growth is on initial stage. On same areas not flooded, there is process of
growing, mostly these are ephemers and ephemeroids; tulips, ebelek, rhubarb,
ranunculus, spurge, pepper wort.
One of the factors of plants degradation on oilfield is pollution of soils by oilfield
sewage waters, salty water, formation waters. High concentrations of water soluble salts
in formation waters (chlorides, sulphates, carbonates) which damnify soil and plants
irrecoverable harm, promote process of technogenic hologenesis, which leads to further
salination of soils, change of their physical-chemical features.
During study of impact of salty waters it was found that almost all plants die during
entrance of such water. The tamarisks can be called stable, but it shows the signs of
damage, expressed in undersizing.
The plant cover near with well, i.e. on technogenic area, changed rather significant.
In the micro depressions filled with salty waters, on the areas with no plants, the saltwort
groups are formed.
In micro depressions which were filled earlier with salty waters, on the areas with no
plants, the alteration of communities is noted towards sagebrush-saltworts.
Recovery ability of plants (area types) based on regions (landscape-geochemical zoning)
is separated on six zones. The Kumkol o/f is located in zone six – desert area. As for the
determining the periods of plants recovering, it is meant that oil is fully removed from
technogenic site by mechanical mean, or burned, which eliminates its further direct
impact.
The communities of semideserts and desert, included to zone six are characterized by
rule of xerophytes, but more importantly there are ephemers widely presented at Kumkol
and they have very short period of vegetation. At the same time extreme environment
conditions unlikely promote fast forming of plant cover at the oilfield, decreasing
possibility of oil direct hit on plants, which supports existing plant formations, as well as
warm climate.
The character of response reaction of plants and plant formations depends of
inhabitation site, type of pollutant and way of pollution. However some general features
are reflected distinctly:
In case of surface spills of oil almost all plants die and recovery starts in 3-5 years
through community, which types depend on area types of plants. The pioneer plants are
ephemers – ebelec, saltwort, weeds;
The external evidence pointing out to the impact of oil and its decay products to the
plants, can be accepted change of anatomist of morphological indices of plants,
formation of necrosis, change of color. The occurrence of mentioned changes at separate
plants can be considered as indicating internal soil pollution with oil;
In case of soil internal pollution with oil the species composition of plant cover is
changing similarly to how it happens in case of surface spill;
The influence of associated gas burning emissions is clearly remains on tree species and
bushes, in such cases appearance of necrosis is seen, change of leaves color, little holes
in leaves, short bines, etc.
Thus at the Kumkol o/f the soil pollution is separated on following types depending on
nature of pollutants – oil, drilling slam, drilling fluids, salty waters, mechanical
degradation, etc:
Soils polluted with oil spills;
Soil polluted by washing fluids;
Soil polluted by salted and formation waters;
Soils polluted by drilling slams;
Soils polluted during oil transportation,
Etc.
Types and level of soil pollution and impact on plants and plant cover at Kumkol o/f
(Table 5)
Table 5 – Types and level of pollution of Kumkol o/f soils
Sources of
pollution
Oil slam
Ecological effect
Salty and
formation water
Depression,
expressed by
undersizment.
Partial extinction of
Oil stains are
plants
seen
The plants are destroyed Oil spills
completely
directly on
surfaces of soil
Washing fluid
Transportation
Necrosis on leaves,
decrease off size,
change of color of
leaves, general
anomaly.
Almost all plants die
External
evidence
The soil seems
to be paved
Level of
pollution
Light
Middle
Strong
Very
strong.
As the soil of Kumkol o/f is sod-podzolic, sandy and clayed, it soaks the oil faster and in
greater amount.
Based on the level of pollution of degraded soils the approaches to its recultivation
change as well.
3.3. Recultivation of soils polluted with oil by biological and mechanical methods.
There are two ways of elimination of soil pollution – removal of polluted layer of soil,
and recovery in natural conditions. But the natural process takes much time. This is
explained by anaerobic conditions which occur after pollution with oil, and
decomposition of components of oil requires molecular oxygen.
Anaerobic microorganisms acquire one tenth of amount of hydrocarbons which
anaerobic types can utilize. During process of auto-purification of soils the condition of
water regime is of high significance. Oil is more stable to microbiological
decomposition in damp soil.
The analysis of available data on ecological and biological features of soils polluted with
oil showed that there are complex physic, chemical and biological researches required
for successful resolving the problem of oil pollution.
Oil absorbers are not only ecologically clean, providing adsorption of hydrocarbon, but
as well they have features of laminating agent for wide variety of soil types.
Their implementation doesn’t only provide full elimination of oil pollution of soil, but
also it provides fast recovery of potential of soils capability. This approved by results of
field tests ‘Ecolana’.
The testing was done on two types of soil with normal nutrition regime, leached
chernozem and gray forest-steppe soil, i.e. soils sensible to oil pollution, with
characteristics of relatively high firmness of structure, which provides significant
difficulties of mechanical removal of oil polluted layer. The tests were done as follows:
The selected sites were treated with oil, 30liters for 1 sq.meters of surface. Such volume
of oil is selecting for soils, and results to inconvertible changes in soil microsphere, in
structure of soil and full loss of fertile qualities, i.e. harvest failure.
The polluted site was treated with oil adsorbent ‘Ecolan’, representing polydisperse
powder of dark-brown color. The oil adsorbent amounted to 20kg on 1square meter of
surface. After applying the oil adsorbent the site was ploughed for the depth of oil
soaking and phenological observations were done. At the same time similar site was
seeded with barley and productivity of this agricultural culture. The results were
compared with control areas of polluted and unpolluted sites. The controlled parameters
in the test were the oil content in soil and productivity of barley. At the same time on a
range of sites specific agronomical activities were done aimed on recovery of soils – the
organic-mineral fertilizers containing nitrogen, phosphorus, kalium were applied.
The test results show that implementation of oil absorber ‘Ecolan’ provides completely
full recovery of productivity soil, for chernozem this time is 3-4 months, and for gray
forest-steppe soils – 7-8 months, in the conditions of biologically active temperatures
(above +10C), at the same time oil polluted soils do not recover during 2 years and
more. Other known agronomic methods (ploughing, fertilizing) on areas where ‘Ecolan’
was not used – did not present the intended effect.
The analysis of received data gives evidence that oil content in soil provides toxic
impact on seeds sprouting. At that the most toxic is oil with overweight of light
fractions. Implementation of ‘Ecolan’ as oil adsorbent allows to decrease its toxicity
based on conversion to less moving form. ‘Ecolan’ itself does not has toxicity for seeds,
and their sprouting is kept on level of 98-103% from control.
It should be remarked that the data on productivity indicated in this work relates to the
first year only, as it is mostly dangerous for plants in terms of ecological condition of
soils.
Further years, as sampling tests showed, the productivity increased at the areas where oil
adsorbent was implemented.
Thus, the oil adsorbent provide efficient elimination of oil pollution of soils and its
consequences, displaying at that clear ecological effect, and it is recommended for
extensive use of industrial practice.
However, ‘Ecolan’ as oil adsorbent provides good results, but it is hardly-to-get and
expensive chemical. Due to this reason, despite of great results of ‘Ecolan’, its wide
implementation is problematic. In this context the perspective chemicals could be cheap
and available wastes, comparing with expensive and imported chemicals. Generally,
such substances can be the wastes of local origin.
3.4. Recultivation of polluted and salted soils using rice hulls
The ecotoxicological researches of oil products pay great significance to search of
regulators of process of self-purification of soil from oil by mean of speeding up
degradation. Practically, such regulators are various wastes of vegetable and animal
origin, such as cuttings, moss, peat, cardboard, cellulose, woodwool, and some mineral
and organic substances working as nutritious substance for soil microorganisms
(transformants and oil products destructors), in this connection it should be noted that
that different regulators impact on transformation and degradation speed of oil products
in soil. They can either accelerate, or slow down these processes.
The wastes mentioned above selected also according to one important factor – price and
availability, which are important in practice.
According to availability and low price the most perspective and efficient oil destructor
is the rice hulls – renewable multi-tonnage waste of rice growing. In this connection we
see the implementation of rice hulls as regulator of soil autopurificatoin as efficient and
reasonable. For these purposes two types of products were used – first is the rice hulls
mixed with other fillers (livestock manure, seeds of wild plants, etc.) and the second one
is based on the rice hulls.
The lab experiments on destruction of oil products in soil were made with samples from
polluted areas of Kumkol o/f. The tested soil sample with oil pollution represented
substance of dark-brown color with strong smell of oil products.
The samples of soil mixed in different ratios with rice hulls in order to evaluate aerating
feature of soil as a result of its loosening with rice hulls as the filler. The soil and hulls
mix was damped with water in order to create conditions for equal mixing of
components, because firm and even contact of soil and hulls promotes intensive
degradation of oil products.
The result of series of tests displayed that in all cases as time passed and mix was stirred,
the polluted soil gradually lost smell of oil and accordingly its color got brighter. In 2-3
month the soil got bright completely and smell was gone. These visual and qualitative
factors testify that the rice hulls is the excellent filler of polluted soil, promoting
intensive degradation of oil products. The rice hulls forms air-space promotes intensive
oxidizing of oil products by oxygen. Thus the main role here is played by the rice hulls
by mean of aerating internal layers of polluted soil.
The intensity of oil products degradation in soil mainly depends on amount of rice hulls,
time of missing, depth of soil aeration, medium temperature, etc. With that the intensity
of oil products degradation increases as the amount of rice hulls increases as well. The
oxidizing intensity also promoted by soil mixing, due to additional transport of oxygen
to the lower layers of soil.
In connection with abovementioned one of the perspective directions of soil cleaning
from oil pollution is implementation of microorganisms, which use oil products as
nutrient solution, and accordingly, decompose hydrocarbon on СО2 and biomasses. We
used biocompost in order to biologically decompose oil pollutions, based on rice hulls.
For this purpose the compost was received by destruction of cellulose-woodwool
structure of hulls using soil aerobic and anaerobic microorganisms. For this we needed
separation of cellulose-destruction micro-organisms with further cultivation in order to
use them later for destruction of fiber of rice hulls.
Thus we developed the technology of biocompost preparation and implementation of
this compost for destruction of oil products, i.e. development of recultivation of oil
pollutes soil at Kumkol o/f.
In order to utilize the rice hulls the soil micro-organisms were separated. Two methods
cultivation of microorganisms were used, accordingly for anaerobic and aerobic.
The general schematic of aerobic decomposition of fiber comes to hydrolysis of fiber
under influence of cellulose ferment produced by microorganisms, before forming
water-soluble carbon compounds, probably sugars. The lasts in the presence of
molecular oxygen get oxidized to the final products with release of a quantity of free
energy:
(C6H10O5)n+H2O+xO2→ R-CHOHCOOH+O2+H2O+x kJ
The formed oxygen acids are good energetic materials for the group of nitrogen-fixing
bacterium of soil, and uranic acids participate in humus formation.
The mold fungi and bacteria take part in aerobic destruction of fiber. The bacteria are the
most energetic destructors of fiber.
Cytophaga (formation Myxobacteriales). Bend flexible sticks with sharp ends (4-6*0,5
mkm). When oil turn into round or oval cysts. Color the fiber in orange.
Cellvibrio. Little, (2-4*0,5 mkm), slightly bend sticks with long ciliae on one end. With
help of this ciliae the fast progressive movements of vibrios are happening. During
destruction of fiber form yellow or green pigment.
Cellfalcicula. Little (2-3*0,3 mkm) fusiform or crescent stiсks with sharp ends and polar
flagellum. Form green spots on bibulous paper.
Conclusion
Increase of oil production volume at Kumkol oilfield as well as development of
new oilfields with disadvantageous conditions resulted in pollution of plant cover of
land with oil and oil products. At Kumkol o/f during exploration, drilling, production,
transportation of oil, spilled oil pollutes plant cover, destroys and kills all types of
plants. In order to solve successfully this problem nowadays in the oil regions it is
necessary to start construction and start of treatment facilities, burial or utilization of
drilling fluids, provide special equipment and means on localization, collection of
spilled oil.
The recultivation work is to be performed in two stages on oil polluted areas. Currently
on Kumkol o/f only first stage of recultivation is carried out – mechanical recultivation.
The oil polluted areas of Kumkol o/f need biological recultivation. As the oil absorbers
are expensive and inaccessible, there is a need to create adsorbent of local origin.
It should be noted that in severe ecological environment during biological treatment
method there can grow pathogen microorganisms, which can be the source of infection.
It is well known that the microorganisms oxidizing process takes much time.
Seeding of grass with branched root network to the polluted soil promotes accelerating
decomposition of hydrocarbons. The positive impact of agriculture plants is explained
by the fact that their root network promotes gas-air regime of polluted soil, enriches soil
with nitrogen. This stimulates growth of microorganisms and accelerates decomposition
of oil and oil products. Also it is important to remember that that plants themselves can
destruct various oil hydrocarbons.
In order to develop technology of recultivation of polluted soil and its optimization it is
necessary to carry out laboratory and experimental testing on fields.
The result of series of tests displayed that in all cases as time passed and mix was stirred,
the polluted soil gradually lost smell of oil and accordingly its color got brighter. In 2-3
month the soil got bright completely and smell was gone. These visual and qualitative
factors testify that the rice hulls is the excellent filler of polluted soil, promoting
intensive degradation of oil products. The rice hulls forms air-space promotes intensive
oxidizing of oil products by oxygen. Thus the main role here is played by the rice hulls
by mean of aerating internal layers of polluted soil.
The intensity of oil products degradation in soil mainly depends on amount of rice hulls,
time of missing, depth of soil aeration, medium temperature, etc. With that the intensity
of oil products degradation increases as the amount of rice hulls increases as well. The
oxidizing intensity also promoted by soil mixing, due to additional transport of oxygen
to the lower layers of soil.
However implementation of rice hulls promotes degradation of oil products by mean of
creation of aeration environment in the soil, i.e. by mean of oxygen delivery for oil and
oil products oxidizing.
In the area of recovery and protection of disturbed components of environment it is
necessary to work out activities on maximum saving and recultivation of land cover of
Kumkol o/f. The striсt following of environment protection measures will allow to save
great spaces without serious natural-climate changes.
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During the Experiment