Environmental impact assessment of oil and gas sector: A case ...

Journal of Soil Science and Environmental Management Vol. 1(5), pp. 86-91, July 2010
Available online at http://www.academicjournals.org/JSSEM
ISSN 2141-2391 ©2010 Academic Journals





Ful Length Research Paper

Environmental impact assessment of oil and gas
sector: A case study of Magurchara gas field

J. B. Alam1, A. A. M. Ahmed2, G. M. Munna1 and A. A. M. Ahmed3

1Department of Civil and Environmental Engineering, Shahjalal University of Science and Technology, Sylhet-3114,
Bangladesh.
2Department of Civil Engineering, Leading University, Sylhet-3100, Bangladesh.
3Department of Business Administration, Leading University, Sylhet-3100, Bangladesh.

Accepted 21 June, 2010

This study focuses on the environmental impact assessment of Magurcherra gas field through
environmental, socio-economical and meteorological study. The major activities involved are seismic
activities, drilling activities, exploration and production. In the case of Magurcherra gas field, improper
planning and drilling activities have created explosion and caused huge environmental damage. In
order to evaluate the environmental damage due to exploration and drilling activities, checklist of
possible environmental impact on the nature, society and socioeconomic activities of the proposed
area has been identified by focus group discussion, survey and sample testing. During the observation
pollution related with noise found as temporary and minor but the air is observed to be polluted by
dust, SPM, SOx, NOx, and CO2 etc. The effects of explosion on the natural forests, land, wildlife, tea
garden, infrastructure, local people and tea garden workers, livestock feeding, communication and
transport etc are measured. During observation, water quality deterioration by spills and leaks of oil
and grease, paints, solvents and chemicals was identified. It was found from the cumulative analysis of
the study that the project is environmentally feasible.

Key words: Magurcherra gas, meteorological study, environmental damage, feasible, socio-economical.


INTRODUCTION

Bangladesh is poor in natural resources by global stand-
in various ways. During dril ing operations, dril ing fluid or
ards. Natural gas is the most important natural resource
mud is continuously circulated through dril pipe and back
that has been discovered and being utilized. Other impor-
to the surface equi-pments to balance underground
tant discoveries include coal, peat, hard rock and modest
hydrostatic pressure, to cool the bit and flush out rock
reserves of limestone, gravel, glass sand and various
cuttings. The location of a dril site depends on the
types of clay. Environmental issues and problems in Ban-
characteristics of the underlying geological formation;
gladesh are now recognized as the key concerns for the
however, environmental impacts can be minimized by
sustainable development of the country. Magurcherra gas
selecting appropriate site for dril ing.
field, 8 km from Srimangal on the road to kamalganj. The
One of the earliest contaminant of the dril ing site is the
gas field caught fire in 1997 and was ablaze for three
mud used while dril ing. Huge quantities of dril ing mud
months, laying waste to betel-nut plantations and tea
are required continuously. The returned mud is recycled,
estates in the vicinity (McAdam, 2008). General y, in the
but final y to be disposed of the effluent mud is usual y
petroleum sector major activities involved are seismic
stored in large pits. Around four to five thousand cubic
activities, dril ing activities, exploration and production.
meters of mud is stored at a time. Eventual y water
During those activities the Surrounding areas are affected
evaporates, leaving behind the clay in the pit and cont-

aminates top soil. Dril ing-mud requires large quantities of

water from the nearby sources. It is necessary to check

whether the water is contaminated by pathogens. If the
*Corresponding author. E-mail: aa_masrurahmed@yahoo.com.
water is contaminated, it must be treated. Large quantities

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Alam et al. 87



Planned project activities
Project activities
Monitoring
(Including mitigation)
Detection of changes
Actual changes in
in the environment
the environment
Evaluation of actual
Actual impact
impacts
Project information


Figure 1. Flow diagram for EIA of the project.



of fluid are let of on the ground or into a nearby stream.
consumption rate and emission factor (Kato and Akimoto, 1992) for
The amount of effluent disposed wil be very damaging
the unit consumption. The Gaussian Plume Model (Peterson, 1978)
for the neighboring areas. It is particularly damaging in
was used to estimate the pol utant concentration. Environmental
the case of off-shore exploration as there is no alternative
Impact Assessment (EIA) was assessed by the graded matrix
system developed by Leopold et al. (1971) in which ‘magnitude’
but to dispose it off into the sea (BUET, 2003). Envi-
and ‘importance’ of the impact in each cel of a matrix can be
ronmental Impact Assessment (EIA) for al petroleum
denoted by assigning numerical values. The flow diagram of the
projects wil al ow the planners and implem-enters to
EIA project shown in Figure 1.
understand the environmental impacts and con-seq-

uences of their projects (NEAB, 1998; DoE, 2001).

The EIA process is thought to consist of six main comp-
Baseline environmental condition of Magurchara gas field
onents: basics; impact identification; description of the

affected environment; prediction and assessment of
Magurchara gas field explosion

impacts; selection of proposed action and documentation
The gas field caught fire in 1997 and caused huge damage of life
in accordance with extant guidelines (Center, 1997). EIA
and property over the whole area. The Magurchara gas field exp-
has been fol owed to define a project and development
losion damaged about 60 hectors of natural forest and 300 hectors
alternatives, the environment on which it may be
of land were burnt. A large part of wild life (Deer, birds, foxes,
affecting, the potential impacts, mitigation alternatives,
monkeys etc) was destroyed or displaced to other places. Around
impact monitoring and public interests. In order to find out
3000 people were affected because 31 hectors of tea garden was
completely damaged during explosion (EPCT, 1997). So, the
possible beneficial and adverse impacts, environmental
overal socio-economic and environmental scenario was highly
impact analysis, construction related impacts, air
affected by the gas field explosion. Preliminary assessment of
pol ution, thermal pol ution of waste resources, noise
environmental damages and deterioration of Magurchara Gas Field
pol ution, soil cont-amination, sediment and dust
Explosion are given in Table 1 and its effects on plants, soil and at-
pol ution, waste disc-harges, occupational health and
mosphere are shown in Figure 2 which shows the deterioration soil
safety, changes in aesthetic environment etc were carried
properties, effects on plants on the Magurchara gas field site.

out in this study. The major objectives of the present

study were (i) to assess the socio-economic impacts of
Noise
these projects, (i ) to assess the impacts on land use

pattern and (i i) to identify and quantity the environmental
Noise, which is seldom recognized as a source of pol ution,
effects of these projects.
constitutes a danger to people’s health through physical, phy-

siological and even psychological stresses. Dril ing operations in
particular are very noisy and pose a threat to the relevant workers

at the site.
METHODOLOGY



Checklist method was used in this study. A questionnaire was
Production of formation water
developed and the fol owing assessment was made based on

expert’s opinion. 100 experts from different fields related to gas and
Oils produced from wel s are invariably accompanied with water as
oil sector were asked and the evaluation was prepared. Pol utants
they are in close association in oil pool. Hence, whenever oil is
emission rates from the power plant are calculated by using the fuel
produced, some quantity of water is also produced. On an average

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88 J. Soil Sci. Environ. Manage.


Table 1. Preliminary environmental assessment of Magurchara gas field explosion.

Resources
Component
Preliminary assessment

Natural forest
60 ha. completely damaged


100 ha completely burnt

Land (300 ha.)
Partly burned observed
Natural resources
Covered with ash and condensate observed
Landslide / Land subsidence observed
Wildlife
Deer, birds, foxes, monkeys etc. destroyed or displaced
Water logging/ pol ution
Observed


Tea Garden
31 ha. completely damaged


1 km Train line damaged
Development resources
Infrastructure
1 km Medal ed road, 2 culverts damaged
1 km Gas line
Livestock
Not observed
Fisheries
Not observed


Local people and Tea garden workers
Around 3000 people affected

Livestock feeding
Not observed

Communication and transport
Disrupted
Human interest
Socioeconomic disruption
Observed
Air pol ution
Not measured
Population / market displacement
Not observed





Figure 2. Effects of Magurchara gas field explosion on the environment.

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Alam et al. 89



Table 2. Possible environmental impacts of pipeline construction.

Environmental component
Positive and negative impact
Mitigation measures


Providing temporary housing, eating and
sanitary facilities for the construction force to
Socio-economic
Negative
prevent overtaxing the local infrastructure



Compensation to owners have to be made for
crop loss, land should general y be acquired by
Land use
Negative
individual agreement with the owners



Soil fertility is to be preserved by segregating
the 30 cm. topsoil layer from common fil
Soil fertility
Negative
material during trenching.

Air quality
Impact is negligible (No)
No mitigation measures are necessary

Potable water used by the construction force
have to be tested to ensure that it meets the


quality standards of Bangladesh for drinking
water. Implementation of Waste Disposal Plan
Surface and groundwater quality
Negative
including proper sanitary facilities for the
construction force and proper disposal of solid
waste generated by the construction activities.

Select alternate routes of pipeline to avoid
forest. Construction force has to be prohibited


from hunting to prevent further degradation of
Fish and wildlife
Negative
this limited resource. Natural fish production
has to be protected by control ing water
pol ution.

Historical and archaeology resources
Impact is considered minor (Negative)




up to 20% water is associated with oil. This water needs to be
stated as negative where the air quality is negligible. A
separated and disposed off in a suitable manner. This water is
minor impact is stated on historical and archaeological
usual y charged with droplets of oil and some salts. Droplets of oil
resources.
are col ected as far as practicable by using demulsifies. Sometime
this water is used for injecting into the water-horizon in the oil field.
Environmental evolution has been shown in Table 3
The quantity of water to be disposed of is colossal and requires
where the identified environmental parameters are
careful thoughts as to how it can be done so that the environment is
analyses for finding out the feasibility of the project by
not damaged.
Leopold matrix. Leopold et al. (1971) have developed

graded matrix system in which ‘magnitude’ and

‘importance’ of the impact in each cel of a matrix can be
RESULTS AND DISCUSSION
denoted by assigning numerical values. This approach is

used of gross screening technique for impact identi-
Environmental impact assessment of dril ing and pipe line
fication purposes. This study used checklist method and
activities was predicted for the Magurchara Gas Field
identified the impact through three different dimensions of
exploration in oil and gas sector. A questionnaire was
environment physical, ecological and socio-economic.
developed and the fol owing assessment was made
The effects are stronger on the eco-logical and socio-
based on expert’s opinion. 100 experts from different
economic environment rather than physical environment.
fields related to gas and oil sector were asked and the
The effect on plane land is evaluated on low and hil y
evaluation was prepared. In Table 2, Negative and
terrain land medium. Most of the components of physical
Positive were used to classify the magnitude of the
environment are evaluated as insignificantly affected.
environmental parameters with the relevant mitigation
Ecological environment of the study area is seriously
measures. The impact on the socio-economic, land use,
affected by the gas field explosion. In the study area a
surface and groundwater quality, fish and wild life is
huge amount of forests are distracted and got high grade

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90 J. Soil Sci. Environ. Manage.


Table 3. Environmental impact evaluation of Magurchara gas field explosion.

Types of impact
Evaluated grading
Negative impact
p
a
c
t



S/No. Environmental component
a
l
u
e

p
a
c
t

i
g
h

e
d
i
u
m
H
)

=

p

*

s

o

I
m
M
e
v
e
r
i
t
y

(
s
)

p
a
c
t

V
N
r
o
b
a
b
i
l
i
t
y

(
p
)

S
(
I
V
o
s
i
t
i
v
e

I
m
I
n
s
i
g
n
i
f
i
c
a
n
t

L
o
w
P
I
m
P
1.
Physical environment









Topography









Plane land
1
6
6






Hil y terrain
2
6
12







Drainage









Congestion
2
2
4






Flash flood










Hazard









Earthquake
1
3
3






Cyclone/storm










Water contamination









Surface water
1
2
2






Ground water
1
1
1






Bio-chemical
2
2
4






Soil









Erosion
2
2
4






Siltration









Pol ution
2
1
2






Air pol ution









SPM, dust
3
2
6






Sox, Nox, CO2
2
5
10







2.
Ecological environment










Terrestrial Flora









A forestation
1
6
6






Destruction of plantation
3
6
18






Aquatic flora









Eutrophication









Nuisance plant
1
3
3






Terrestrial Fauna









Disturbance to wildlife
4
3
12






Disturbance to migrated birds
3
4
12






Aquatic fauna









Destruction of wetland
2
3
6







3.
Socio-economic environment










Loss of land









Agriculture
4
4
16






Residential/Community
2
2
4






Industrial/Commercial
2
3
6

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Alam et al. 91
Table 3. Contd.


Impact On










Crops/Plantation
2
6
12







Residential/Community
1
3
3







Commerce/Industry
1
3
3








Indirectly affected










Household
1
3
3







Transportation










Land communication
2
4
8








Health and Safety










Workers
3
6
12







Local people
2
4
8







Noise to neighbors
4
2
8








Disturbance to










Social structure
4
2
8







Major sources










Irrigation
2
5
10







Farming
2
4
8









in evaluation. The effects on wildlife and migrated birds
erosion has to be minimized with the measures for
are evaluated as low and medium, respectively.
conserving soil during stream crossings and during
Distribution of wetland is also considered by the gas field.
trenching activities.
In socio-economic environment agriculture sector, crops

and plantation, and farming are affected and the effects

are evaluated as medium. The workers of the gas field
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DoE (2001). “EIA Guidelines”, Department of Environment, Ministry of

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and Gas Sector”, survey work conducted by Engineering Planning
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related with noise found as temporary and minor but the
air is observed to be pol uted by dust, SPM, SOx, NOx,
and CO2 etc. Water used by the cons-truction force have
to be tested to ensure that it meets the quality standards
of Bangladesh for drinking water, or it should be
chlorinated so that the tested chlorine residual is 0.2 mg/l
or greater, after 10 min of contact time. Implementation of
Waste Disposal Plan including, proper sanitary facilities
for the construction force and proper disposal of solid
waste generated by the construction activities. Soil

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