Environmental Impacts Of Oil And Gas Environmental Sciences Essay

Oil and gas companies have been conducting exploration projects worldwide for years in an attempt to find and extract the extremely valuable global resource known as petroleum (BERA 2006). Oil and gas exploration encompasses testing subsoil, using sophisticated technology and is not without any environmental damage. A major challenge in exploration of oil and gas is the ecological significance of repeated exposures to very low-level releases of various chemicals, the removal of vegetative cover, impact on fisheries, and biodiversity loss. Most of the developing countries in Africa are desperate for economic success and this is usually the major driving force behind sanctioning any exploration activities in this region. The problem is that most of these countries are inexperienced in the oil industry and therefore they take into consideration very few environmental implications. In lieu of this, it becomes very prominent that ignoring the immediate and long-term impacts of Ghana’s oil and gas exploration activities will have a damaging effect on the surrounding biodiversity and ecosystem.

In 2007, Ghana confirmed that an estimated 800 million barrels of oil was found in the southern coast of the Gulf of Guinea by Tullow Oil. Tullow Oil is a Uk based company and is involved in oil exploration in Ghana. The people of Ghana were instantly excited and looking forward to reap the benefits of the discovery but unfortunately the potential detrimental issues associated with exploration were overlooked. The economic benefits associated with this discovery had been prioritised over environmental considerations. The good thing is that Ghana does not have to look far to learn lessons of the past. Nigeria being a few miles away from Ghana is a prime source of information to learn from.

Potential impacts refer to both the negative and positive effects on the quality and quantity of the biotic and abiotic factors of the physical environment. In this study, the accentuation is on the negative effects of oil exploration activities on the ecosystem of the coast. The boundary limits for a coastal area is between 50 metres below mean sea level and 50 metres above tide level from the shore. It includes coral reefs, intertidal zones, estuaries, coastal aquaculture, and seagrass communities (Millenium Ecosystem Assessment, 2003:54). Considering the associated environmental impacts of oil and gas exploration, it is clear that practicable environmental regulations are critical in controlling and minimizing environmental impacts.

The areas for oil and gas exploration in Ghana include the Nzema East Municipal, the Secondi Takoradi Metropolitan, the Ellembelle, the Ahanta West, the Jomoro, the Agona West District Assemblies. The surrounding communities are cape three points, half Assini, Ellembelle, Princes Town, Axim, Discove, Busua, Miamia, Akwidae,Wotera, Sekonde, Eziama, Nkroful and Secondi-Takoradi. These areas will most likely be affected by oil and gas exploration activities.

GhanaWestCoastMap

Figure : Coastal line of Ghana

C:UsersJoseph Addo-YoboDesktopghana-offshore-oil-map.jpg

Figure : Ghana’s offshore oil fields

OBJECTIVES

The objectives of this project are:

To analyse the environmental impacts from oil and gas exploration on the coastal ecosystem and biodiversity in Ghana.

To determine the various levels of water quality parameters such as colour, conductivity, total dissolved solids, potassium content, calcium content, magnesium content, phosphate content, lead and arsenic content.

To determine the concentrations of oil/grease in water samples that have been collected and use concentrations as indicators of pollution from oil exploration.

To compare levels of oil/grease in water samples with that of the World Health Organization (WHO) and Ghana Environmental Protection Agency ( GEPA).

To make recommendations to help manage the associated environmental impacts.

Research Questions:

What are the environmental impacts of oil and gas exploration on the coastal ecosystem?

The thesis begins with the examination and analysis of potential environmental impacts that will probably arise from oil and gas exploration. According to the E&P Forum/UNEP Technical Report (1997) the potential impacts may depend upon many other things among which include: The stage of the process, the size and complexity of the project, the nature and sensitivity of the surrounding environment, the effectiveness of planning and migration techniques. Such impacts include atmospheric, aquatic, terrestrial and human impacts.

What recommendations will help manage the associated environmental impacts from oil and gas exploration in Ghana?

It is not enough to just identify the likely hazards from exploration without recommending measures to cope with or minimize the possible dangers. Recommendations become more essential in view of the fact Ghana is very inexperienced in the industry and legislations are not fully formulated to cope with the environmental hazards that accompany any exploration activity. The thesis gives explicit recommendations based on the findings as lessons from similar studies elsewhere.

METHODOLOGY

An attempt was made to determine some of the impacts from oil exploration on the Jubilee field area and the environmental coastline by a series of random sampling and by comparing results.

An overview of the environmental baseline and ecology is given. This was based on the six oil districts in Ghana and the Jubilee field area.

The impacts are categorized into minor, moderate and major.

Exploration activities at each phase are presented.

Random sampling techniques were carried out to determine whether there was pollution in the water from the exploration activities.

A review of the current legislation frameworks in Ghana to cope with these issues.

Short term and long term recommendations made to help minimize the impacts.

ORGANISATION OF REPORT

This report is divided into six chapters. The structure is as follows:

Chapter one gives a brief introduction and objectives for conducting this research. The background to the setting and methodology are also included.

Chapter two entails the literature review. The location for the oil exploration activities and general approach to oil and gas exploration are described.

Chapter three includes what this research comprises of and is discussed in the scope such as the possible impacts on the environment.

Chapter four reviews the results of the study presented and are analyzed.

The final chapter ends with recommendations, both short term and long term to help minimise the impacts and talks about the current legislation frameworks in place in Ghana to cope with the impacts reviewed in this research.

The main conclusions are also presented and further recommendations for further studies made to help address pertinent issues recognized under this study.

Presented below is a summary of the research structure:

Research Objectives

Research Questions

Literature Review

Methodology

Literature Reviews

Potential Impacts

Observations

Results and Analysis

Discussion

Conclusion

Recommendations

CHAPTER TWO

LITERATURE REVIEW

2.1 Overview of oil and gas exploration activities on the coastal zone of Ghana

Oil and gas exploration involves prospecting surveying and exploration drilling. The prospecting surveying starts with a review of geological maps to identify major sedimentary rocks basins. This may be followed by an aerial photography to identify promising geological formations such as faults and anticlines. A field assessment is done to gather more detailed information. The three methods used for surveying include seismic, magnetic or gravity method. Exploration drilling involves drilling exploration wells to confirm the presence of hydrocarbons. In Ghana, mobile offshore drilling units (MODU) are used.

Hydrocarbon exploration in Ghana dates back to 1986 when oil seeps were found in the offshore Tano basin. This eventually led to drilling of exploration wells in the vicinity of Half-Asini (GNPC, 2012). A total of 10 discoveries have been made and about 79 exploration wells drilled in Ghana. None but the Saltpond field, discovered in 1970 and located approximately 100km west of Accra. Currently, Exploration activities are ongoing in Ghana’s four sedimentary basins namely the Tano basin, central basin, keta basin and voltaian basin (GNPC, 2012).

The most promising discovery so far is the Jubilee field which was discovered in 2007. The Jubilee Unit area covers part of the Deepwater Tano and West Cape three points license areas. Kosmos Ghana HC, an exploration company drilled the Mahogany-1 well in the West Cape Three Points block. Ghana’s oil and gas exploration activities do not come without environmental challenges. These challenges may arise from one or more of the following: project footprint, operational discharges, air emissions, waste management and risk of a blow-out during drilling.

2.1.1 Surveying Stage

In the first stage of exploring for rock formations bearing hydrocarbons, geological maps are reviewed in desk studies to identify major sedimentary basins (E&P Forum/UNEP 1997). Desk study indentifies areas with favourable geological conditions. No potential requirements are needed on ground to do this study. The area is identified based on relief and physical geographical analysis.

Based on the results and assumptions from the desk study, if favourable landscape features are revealed, then low hovering aircrafts are used to do aerial survey. The low-flying aircraft over the study are provides overview and peripheral information.

A seismic survey is mainly used in hydrocarbon (oil and gas) exploration to investigate the Earth’s subsurface structure. This method uses the principles of reflective seismology to acquire and interpret seismic data, which allows the estimation of the Earth’s composition (Morgan, 2003). The seismic method is heavily dependent on differing reflective properties of sound waves to identify hydrocarbon bearing rocks in the earth’s subterranean zones. An energy source transmits a pulse of acoustic energy into the ground which travels as a wave into the earth (E&P Forum/UNEP, 1997). At each point where different geological strata exist, a part of the energy is transmitted down to deeper layers within the earth, while the remainder is reflected back to the surface (E&P Forum/UNEP, 1997). Here it is picked up by a series of sensitive receivers called geophones or seismometers in onshore, or hydrophones submerged in water offshore. The signals are transmitted by cables, amplified, filtered, digitalized and recorded for onward interpretation.

Figure : Offshore seismic activity

2.1.4 Exploration drilling

Drilling of exploration wells are activities that come after seismic data have been interpreted and also after the volume and area of oil and gas resources from potentially productive geological formations been quantified. If oil/gas is discovered, then there will be a need to drill some development wells.

Once in position, a series of well sections of reducing size are drilled from the rig. A drill bit, connected to the drill string suspended from the rig’s derrick, is rotated in the well. Drill collars are connected to add weight and drilling fluids are distributed through the drill string and injected through the bit. The fluid has a variety of functions that it performs. It imparts hydraulic force that assists the drill bit’s cutting action, and it cools and lubricates the bit. It eliminates cuttings from the wellbore and protects the well against high formation pressures. When each well section has been drilled, steel casing is run in hole and cemented in place to prevent well failure. When the total reservoir depth is reached the well may be completed and tested by running a production liner and equipment to allow for the flow of hydrocarbons to the surface to establish reservoir properties such as porosity and permeability in a test separator. Any unwanted gas that is produced may be flared.

2.1.5 Appraisal Stage

Appraisal is carried out after a successful exploration drilling to determine if the reservoir is economically feasible or viable. It helps in determining the extent and nature of the reservoir by drilling several other wells in the same site. The technical procedures applied to exploratory drilling also applies to appraisal drilling (E&P Forum/UNEP, 1997). This requires additional drilling sites that could be reduced by directional drilling hence reducing the ecological footprint and the amount of waste generated.

2.2 Environmental Baseline and Ecology

This chapter provides a description of the environmental situation against which the potential impacts of the oil and gas exploration can be assessed and future changes monitored. The chapter presents an overview of the aspects of the environment relating to the surrounding area in which the exploration phase will take place. This includes the Jubilee field unit area, the Ghana marine environment at a wider scale and the four Districts of the Western Region bordering the marine environment.

The Jubilee Unit area and its regional setting are shown below. This area is approximately 132 km west-southwest of the city of Takoradi, 60km from the nearest shoreline of Ghana, and 75km from the nearest shoreline of Cote d’Ivoire.

http://subseaworldnews.com/wp-content/uploads/2012/02/Jubilee-Field.jpg

Figure : Location of Jubilee Field

Air Quality

The principal source of environmental contaminants from the atmosphere across central Africa is biomass due to the burning of firewood and controlled burning in savannah places for farming. It has been estimated that Africa accounts for almost one half of the total biomass burnt worldwide (Andrae, 1993). The result of this biomass combustion is the emission of carbon monoxide (CO), oxides of nitrogen (NOx), nitrous oxide (N2O), methane (CH4), non methane hydrocarbons and air particulate matter.

Upwelling

The term upwelling is used when cold, nutrient-rich, water goes from the ground up to the surface, leading to an in increase in plankton productivity in the surface waters. The considerable upwelling period along the Ghana shore occurs from July through to September/October, while a minimal upwelling happens between December and January/Feburuary. The rise in plankton productivity during the periods of considerable and minimal upwelling attracts pelagic fish species into the upper layers of the water column, thereby increasing the rate of fish capture.

Fish Ecology

Seasonal upwelling influences the composition and distribution of fish species in the water bodies of Ghana. The transport of cooler, heavier and nutrient-rich deep waters to the warmer, usually more nutrient-depleted surface water during times of upwelling promotes very high levels of primary production in phytoplankton. This therefore leads to an increase in the production of zooplankton and fish. The fish species found in Ghanaian waters can be divided into four main groups, namely:

â€¢ small pelagic species

â€¢ large pelagic species (tuna and billfish);

â€¢ demersal (bottom dwelling) species; and

â€¢ deep sea species.

The most important small pelagic fish species, both commercially and as prey for larger fish found in the coastal and offshore waters of Ghana are:

Water Quality

Water column samples were taken at two depths, namely sub-surface and at 100m depth. Water alkalinity (pH) was measured on a subsample. Water samples were collected for metal analyses, nutrients, total dissolved solids and suspended solids (EIA, 2009).

Water samples were evaluated for a range of determinants including metals and nutrients and the results were found to be:

Mercury (Hg). Most stations had Hg concentrations below the detection limit, ie below 0.2 mg/l).

Barium (Ba). Ba concentrations were higher in the surface samples and ranged from 5.96ppb to 5.43 ppb for the surface samples and 5.43 ppb to 5 ppb.

Lead (Pb). No Pb was detected in any samples.

Phosphorous (P). The concentration levels of total phosphorous were higher for samples from the 100m depth than for samples from sub-surface for all the stations. The highest TP concentration recorded for the sub-surface samples was 0.0192 mg/l and the lowest concentration was 0.0145mg/l.

Seabirds and Coastal Birds

Ghana’s seaside swamplands and lagoons form an environmentally essential environment, offering providing, roosting and nesting sites for thousands of migratory and local wildlife. Eight of these seaside wetlands: Keta Lagoon, Songor Lagoon, Sakumo Lagoon, Korle Lagoon, Densu Delta, Muni Lagoon, Elmina Salt Dishes and Esiama Seaside, qualify as globally essential swamplands under the Ramsar requirements of assisting 20,000 waterfowls or 1% of the population of a waterfowl species. Of these only Esiama Seaside falls within the position at most chance of experiencing an oil spill and has an exotic beach believed to back up over 10,000 wildlife.

However, there are several other lagoons and swamplands such as Domini Lagoon, Amunsure Lagoon, Ankobra (Ankwao) Estuary, Kpani-Nyila Estuary and the Ehnuli Lagoon which are essential for fowl feeding and reproduction places. They consist of considerable amounts of waterfowls such as typical tern, egret, typical sandpiper, ringed plover and greyish plover. As a whole, the stretch of coastline west of Cape Three Points is regarded as extremely delicate for seaside fowl species.

Direct death rate of wildlife in the event of an oil spill is often the most widely recognised danger. While impacts to birds can happen offshore in the marine environment, the more noticeable impacts are often experienced if oil gets to the coastal waters. Oil spills impacting coastal waters near major bird colonies during the reproduction period can be particularly severe since birds are feeding intensively and often dive through the surface oil to feed on fish. Birds are affected by oil pollution in the following three key ways.

â€¢ Stains of oil on the plumage may destroy the insulating and water repelling properties which may ultimately cause the death of the bird.

â€¢ Toxic effects after the ingestion of oil during preening, ingestion of oiled prey, inhalation of oil fumes or absorption of oil through skin or eggs.

â€¢ Indirect effects resulting from destruction of bird habitats or food resources.

Coastal bird species and habitats in Ghana are regarded as highly sensitive to potential impacts resulting from an oil spill that reaches the coastline.

Marine Mammals

Ghana’s offshore areas are known to support significant marine mammal populations such as certain protected and sensitive species. Examples being the humpback, fin whales and Atlantic spotted dolphins. While the periodic distribution of these species is not well understood it is likely that during the months of September and October a variety of species of whale and dolphin s pass through these areas.

Marine mammals are usually less sensitive to oil spills than seabirds as they will tend to identify the position around a surface oil slick and avoid any breaching or feeding behaviours that may bring them into immediate contact with oil. However, marine mammals are still delicate to results from oil spills, and in particular from the hydrocarbons and chemicals that escape from the oil, particularly in the first few days following a spill.

Although it is likely that certain species of marine mammals happen to be in the area offshore Ghana, they are regarded as less sensitive (compared to turtles and birds) to any impacts resulting from an oil spill as they will usually avoid the affected area.

CHAPTER THREE

METHODOLOGY

Magnitude of Impacts

This is the degree of change brought about in the environment. An attempt is made to quantify the magnitude of impacts to the natural and social environment. The magnitude of impacts covers all areas of the environment and is discussed as follows:

The nature of the change in the environment including what resources or receptors have been affected and how;

The spatial extent to which the area has been impacted and what proportion of the population or community has been affected;

The temporal extent such as duration, frequency and reversibility of impacts;

The probability of impacts occurring as a result of accidental or unplanned events.

Table : Magnitude Definitions

Impact Magnitude

Spatial Scale

Temporal scale

An assessment of the magnitude of impacts is provided that takes into consideration all dimensions of the impact described above to determine whether an impact is low, medium or high magnitude.

Sensitivity of Resources and Receptors

The significance of an impact of given magnitude depends on the sensitivity of resources and receptors to that impact. For ecological impacts, sensitivity can be assigned as low, medium or high based on the importance of habitats and species. For habitats, these are based on naturalness, extent, rarity, fragility, diversity and importance as a community resource.

Table : Species Value/ Sensitivity Criteria

Value /

Sensitivity

High

Criteria

Not protected or listed

and common / abundant; or not critical to other ecosystem functions.

Not protected or listed.

A species that is common globally but rare in Ghana; important to ecosystem functions; or under threat or population decline.

Specifically protected

under Ghanaian legislation and/or international conventions.

Listed as rare, threatened

or endangered.

The magnitudes of impact and the sensitivities are looked at in combination. This is to evaluate whether an impact is, or is not significant and if so its degree of significance defined as either Minor, Moderate or major.

â€¢ short-term disturbance directly to the seabed (eg from sediment suspension), with secondary impacts on the benthic and demersal community, during installation of subsea infrastructure;

â€¢ permanent habitat and associated species loss or damage from coverage of areas of seabed by moorings, well manifolds, well heads, riser bases, flowlines and umbilicals; and

â€¢ permanent changes to the habitat arising from the physical presence of subsea infrastructure (eg sediment disturbance and reef effects from marine organisms growing on subsea infrastructure).

Minor Impacts

Impacts from flaring on Birds. Many birds chose to migrate at night to take advantage of the more stable weather conditions which benefit migration, and for some species to avoid daytime predators. Artificial lighting, however, may affect nocturnal movement of birds. Previous research has found that migrating birds (especially songbirds, waders and ducks) may circle around offshore lit structures including offshore platforms. The effects are reported to be pronounced during periods of low cloud and fog, when there is poor visibility. Erickson et al. (2001) suggested that lighting was a critical attractant, leading to collision of birds with tall structures, and recent research appears to support the role of lighting. Ongoing research in the Dutch sector of the North Sea for NAM (Nederlandse Aardolie Maatschappij) suggests that the red end of the spectrum components of conventional platform lighting affect birds, and that the use of green spectra could significantly reduce the effects on the populations of those species most at risk (Bruinzeel 2009). Birds which are drawn to lit platforms often circle around for prolonged periods resulting in fatigue. They sometimes land on the platforms, or collide with the structures, and if there is little food or water for them on the platform, this can result in their death. There are Important Bird Areas (IBAs) along the coastline of Ghana and the Ivory Coast which support migratory bird species known to use the East Atlantic Flyway. Such species occur along the west coast of Africa, including red knot (Calidris canutus) and sanderling (Calidris alba). (Boere and Stroud 2006). Detailed information about African bird migration routes is less well understood and is the subject of ongoing research (Birdlife 2009). Whilst there is a risk of migrating birds encountering the platform, many of the effects described above are based on research undertaken in the North Sea, and similar weather conditions in the location of the Jubilee field are not expected. Research in the North Sea also found that in more stable conditions when skies were clear and there was little cloud, few birds responded to lights (NAM 2007). It is also likely that some of the bird species which are migrating through this area will do so during the daytime, and hence should be less affected by lighting. The Jubilee joint venture partners have had drill rigs deployed in the area for over 2 years and have not reported unusual bird attraction or congregation. The risk of impacts on birds from flaring is considered to be low and not significant. As part of the routine reporting from the FPSO the presence of significant bird landings during the year and/or records of any bird deaths will be recorded to inform any future mitigation strategies.

â€¢ Impacts from flaring on Turtles. There is the potential that turtles will be attracted to the platform at night where hatchlings could be subject to increased predation by birds and fish that also are attracted to these structures. The risk of any impacts on turtles and turtle hatchlings from lights is considered to be low and not significant.

â€¢ The impacts to marine mammals and turtles from vessel collision and marine debris. Collisions have been known to occur worldwide and also in West Africa (Félix and Van Waerebeek, 2005; Van Waerebeek et al., 2007) and increased marine vessel traffic between the Jubilee field and Takoradi port will increase the risk of collisions. The increased risk of collision is considered to be low however given the relatively low volume of project related traffic and the speed that they move at (typically moving at less than 12 knots). Marine mammals and marine turtles are most sensitive in areas with fast moving vessels which frequently change direction and are more able to avoid the large, relatively slow moving support vessels associated with the project. Disposal of solid waste to sea will not occur from the FPSO, MODUs or support vessels, with the exception of treated kitchen waste and treated sewerage, which will be macerated. Discharges during the previously permitted well drilling operations, including drill cuttings discharges, are addressed in Annex B. The risks to marine mammals and marine turtles from vessels collisions and damage from marine debris associated with the project are considered to be small and are assessed as not significant.

â€¢ Impacts from noise. Activities in the Jubilee field will be located approximately 60 km offshore, away from any sensitive noise receptors. Onshore noise at the port in Takoradi from the project is assessed as not significant as activities will be within an existing busy port. Noise on the FPSO will be controlled for occupational exposure reasons so that workers in open areas will not require to wear hearing protection (the WHO standard is 85 dB without hearing protection). A 85 dB noise source (measured at 10 m from source) will have attenuated to 45 dB at 1,000 m. Fishermen and other marine users not associated with the project will be outside the 1,000 m exclusion zone centred on the turret and therefore at least 500 m from the FPSO. The risk of noise exposure above the 85 dB standard is therefore extremely unlikely. Noise from helicopter flights to and from the Air Force base at Takoradi and the Jubilee field has the potential to cause disturbance. Careful flight planning to avoid sensitive areas will avoid significant impacts. This includes a minimum flight height of 2,300 feet (710 m) above the Amansuri Wetland IBA to avoid disturbance to wildlife.

3.2 Impacts from physical structures

3.2.1 Impacts from flaring on Birds.

Many birds chose to migrate at night to take advantage of the more stable weather conditions which benefit migration, and for some species to avoid daytime predators. Artificial lighting, however, may affect nocturnal movement of birds. Previous research has found that migrating birds (especially songbirds, waders and ducks) may circle around offshore lit structures including offshore platforms. The effects are reported to be pronounced during periods of low cloud and fog, when there is poor visibility. Erickson et al. (2001) suggested that lighting was a critical attractant, leading to collision of birds with tall structures, and recent research appears to support the role of lighting. Ongoing research in the Dutch sector of the North Sea for NAM (Nederlandse Aardolie Maatschappij) suggests that the red end of the spectrum components of conventional platform lighting affect birds, and that the use of green spectra could significantly reduce the effects on the populations of those species most at risk (Bruinzeel 2009). Birds which are drawn to lit platforms often circle around for prolonged periods resulting in fatigue. They sometimes land on the platforms, or collide with the structures, and if there is little food or water for them on the platform, this can result in their death. There are Important Bird Areas (IBAs) along the coastline of Ghana and the Ivory Coast which support migratory bird species known to use the East Atlantic Flyway. Such species occur along the west coast of Africa, including red knot (Calidris canutus) and sanderling (Calidris alba). (Boere and Stroud 2006). Detailed information about African bird migration routes is less well understood and is the subject of ongoing research (Birdlife 2009). Whilst there is a risk of migrating birds encountering the platform, many of the effects described above are based on research undertaken in the North Sea, and similar weather conditions in the location of the Jubilee field are not expected. Research in the North Sea also found that in more stable conditions when skies were clear and there was little cloud, few birds responded to lights (NAM 2007). It is also likely that some of the bird species which are migrating through this area will do so during the daytime, and hence should be less affected by lighting. The Jubilee joint venture partners have had drill rigs deployed in the area for over 2 years and have not reported unusual bird attraction or congregation. The risk of impacts on birds from the FPSO lights is considered to be low and not significant.

3.2.2 Effects from sediment disturbed during infrastructure installation.

Sediment may become disturbed and suspended in the water column by project activities undertaken on or near the seabed such as installation of flowlines, moorings, manifolds and riser bases. Suspended sediment could lead to the smothering of sessile species and possible secondary effects such as impacts to the respiration of benthic organisms and demersal fish. The duration of installation activity is relatively short-term and localised, and the water quality and exposed populations are of low sensitivity and are expected to recover relatively quickly.

Loss of or damage to marine habitats. The positioning of subsea infrastructure, in particular flowlines, will result in the loss of or damage to seabed habitats and associated communities. The total area of seabed that will be directly affected by the physical presence of subsea infrastructure is relatively small at approximately 2.3096 ha (23,096 m2). For comparison, the Jubilee Field Unit Area covers 110 km2 (and the area within which the subsea infrastructure is located covers approximately 34 km2), therefore installation of the subsea infrastructure will directly impact less than 0.1% of the seafloor in the Jubilee Field Unit Area. The mortality of most organisms beneath installed infrastructure is predicted, particularly for sessile species (which typify the benthic communities) where avoidance and vertical migration is generally not possible. The impact on seabed habitats and species will be very localised, with the area affected being a small percentage of the total area of similar habitats in this offshore, deepwater location and consequently the loss of areas of muddy/silty habitat is considered to be low magnitude at a community ecology level.

Loss of fish prey organisms. The loss of or damage to seabed habitats and associated communities will reduce prey availability to demersal deep water fish species in the area that rely on benthic food sources. The impacts to benthic organisms are considered to be very localised and the total loss will represent a small fraction of the food sources available to fish predators. In addition, the fish species impacted are highly mobile, travel large distances for food and will be able to source prey from other locations. The magnitude of these changes will be low.

Interaction between Underwater Sounds and Marine Ecology

Sources of Noise

Sounds in the marine environment can be categorised as either naturally occurring or anthropogenic (human produced) in origin. Natural sources of sound include marine mammal vocalisations; and sounds from other marine life, wind, rain, and waves. Anthropogenic sounds come from shipping, fishing, dredging, exploration and production activity, sonar (navigation, fishing, and defence), seismic survey sources and construction (eg percussive piling). Most noise sources are intermittent in a given area, eg vessel movements (other than in busy shipping lanes where they are near continuous). For offshore operations the fixed installation will produce continuous or near continuous noise as well as intermittent noise from visiting vessel movements.

The main sources of underwater sound associated with the project can be categorised into the following.

â€¢ Propeller and Thrusters. Noise from vessel propellers and thrusters is predominately caused by cavitation around the blades whilst transiting at speed or operating thrusters under load in order to maintain a vessel’s position (ie dynamic positioning). Noise produced is typically broadband noise, with some low tonal peaks.

â€¢ Machinery Noise. The source of this type of noise is from large machinery, such as large power generation units (eg diesel engines or gas turbines), compressors and fluid pumps. The nature of sound is dependant on a number of variables, such as number and size of machinery operating and coupling between machinery and the deck. Machinery noise is often of low frequency and tonal in nature.

â€¢ Equipment in Water. Noise is produced from equipment such as flowlines and subsea valves.

Sources of Emissions

Emissions to atmosphere from the project will result primarily from combustion of fossil fuels (natural gas and diesel) for energy generation; emissions from intermittent flaring during commissioning and non-routine operations (during upset and maintenance conditions); venting of hydrocarbons; and fugitive emissions during cargo transfer. Sources of air emissions will be from the following activities:

â€¢ MODU operations for well completions (power generation exhaust emissions);

â€¢ FPSO operations (power generation exhaust emissions and non-routine flaring);

â€¢ marine support vessels and helicopters (power generation exhaust emissions);

â€¢ filling, offloading and operation of export tankers (exhaust and fugitive emissions); and

â€¢ dust and exhaust emissions from increased traffic and dry handling of dry goods.

These emissions, except dust emissions, have been quantified and summarised in Chapter 2, Section 2.8.1. Air emission calculations from fuel uses are presented in Annex E. The total estimated annual emissions for various project activities, including support vessel activity, is summarised in Table 5.8. The well completions undertaken by MODUs, and the installation and commissioning of the FPSO are estimated to be undertaken over a period of 18 months.

There is limited data available on national emissions. Data from WRI for 1995 is also presented in Table 5.8. It is considered that current emission estimates for Ghana would be significantly higher than the 1995 estimates which do not

include the significant emissions from sources such as biomass burning, wet soils, lightning and shipping (see below).

4 Greenhouse Gas Emissions

GHG Emission Volumes

The standards for reporting GHG emissions and country targets are managed by the United Nations Framework Convention on Climate Change (UNFCCC) which was ratified by Ghana in 1995. Ghana prepared an Initial National Communication( 1 ) in 2000 which provides official estimates of total greenhouses gas emissions from Ghana. Ghana GHG emission estimates reported by the World Resource Institute (WRI)( 2 ) in 2003 provides annual

CO2 emission estimates of 4.4 million tonnes in 1998 which is an increase of

23% since the previously reported data in 1990. This is considerably less than the 1998 estimate for Nigeria of 78.45 million tonnes and the 1998 estimate for

Sub-Saharan Africa of approximately 515 million tonnes.

The breakdown of emissions for 1999 (WRI 2003) indicates that the main sectors producing CO2 were transport, electricity and heat production, and residential. The energy industry( 1 ) contributes a relatively small source of emissions (3%) (see Figure 5.5).

It is likely that the overall GHG emissions from Ghana will have risen considerably since 1998. If a similar rate of increase has taken place as was experienced between 1990 and 1998, expected emissions would now be approximately 5.4 million tonnes.

Acid rain looks, feels, and tastes just like clean rain (EPA, 2009). Oil and gas exploration is associated with sulphur and other harmful elements and agents of acidic rain. During gas flaring these elements combine chemically producing acidic substances that go into the atmosphere and biosphere causing harm to the environment and imbalance in the ecosystem. The sulphur content in oil production reacts in oxygen exothermically producing various sulphur oxides (SOx) especially sulphur (IV) oxide (SO2). When rain falls the SO2 goes into a chemical reaction (dissolves) with hydrogen producing trioxosulphate (IV) (H2SO3) an acidic compound that is potentially corrosive. Further reaction of trioxosulphate (IV) yields tetraoxosulphate (VI) (H2SO4) acid which is more vulnerable and catastrophic than the former intermediate product. When these compounds are accompanied by rain water unto the roofs, they cause corrosion of roofing sheet (zinc and aluminum) in the Niger Delta. These agents also increase the oxidation rate of copper and bronze materials (Reisener et al., 2005). When these compounds fall on the soil and crops, the soil becomes acidic and crops wilt causing low agricultural yield leading to hunger and starvation in the Niger Delta. Besides, the effects of the corrosive nature of acidic rain on oil installations and pipelines can not be over emphasized. It results in short life span of production equipments leading to leakages, rupture and other forms of equipment failure. Below is chemical reaction leading to acidic rain:

S + O2 ƒ¨ SO2 + (H2O) ƒ¨ H2SO3 + (1/2O2) ƒ¨ H2SO4

Other agents of acidic rain include Nitrogen Oxides (NOx) which reaction yields HNOx another corrosive compound capable of wilting and corrosion. The equation for the reaction is given below:

1/2N2 + O2 ƒ¨ NO2 + (1/2H2O) ƒ¨ HNO3

NO2 and HNO3 are both acidic in composition and have similar effects on the environment as SO2, H2SO3 and H2SO4. All this acidic components accompanied by rainfall could be history if zero flare is achieved in the Niger delta. To cap it all, these substances have the capability of itches, skin burn, and other allergies. Besides, it could lead to skin cancer and other health related problems in an extreme case (EPA, 2009). Below are pictures showing the formation and effect of acidic rain:

Water is considered polluted when it is altered in composition or condition directly or indirectly as a result of activities of man so that it becomes less suitable for some or all of the uses for which it would be suitable in its natural state (Helmer, 1975). Any undesirable change in the natural characteristics of any state of matter is, therefore, pollution or damage (Adenuga A. O. et al., 2002). When water is polluted it does not only affect humans but also plants and animal; it in fact distorts the natural ecosystem causing huge impact on the environment. As a result of oil spillage and other related impacts the E&P companies are the major water polluters in the Niger Delta. The upstream and downstream activities of these companies which include: offshore drilling and completion, development and production, tank wash, effluent discharge, refining and transportation. Each of the aforementioned activities generates enormous amount of waste and in most cases ends up in waterways. Oil spillage and drilling fluid are the most visible water pollutants in the Niger Delta region as oil and water are immiscible. Old oil facilities and installations such as pipes rupture and leak oil into the surrounding environment. These leakages and spills from pipes and valves end up polluting the waters and waterways, making them unfit for consumption, agriculture and other applications.

The after-effect of oil and gas on water could be classified as externality. When something or someone is affected negatively directly or indirectly by the activities of another without proper agreement, knowledge and consent is termed externality.

Fish Populations

Deep water fish species and large pelagic fish species (eg tuna and billfish)

will be present in deep water in the Jubilee Unit Area and could be affected by the presence of subsea infrastructure on the seabed. Pelagic species which inhabit the surface layers of the water column are likely to be attracted to the platforms. During the night fish species may also be attracted by light emissions from the FPSO. The exclusion zone placed around the platforms will afford some protection from fishing activity. No mitigation measures are proposed and the residual impact of the physical presence of the FPSO and subsea infrastructure was assessed as being a positive impact of minor significance.

Onshore Waste Disposal

Project generated waste will need to be disposed in a manner that avoids significant environmental impacts. Most project wastes will be disposed at landfill sites in Ghana. Potential impacts could result from the following sources.

â€¢ Contamination of soils, groundwater and surface waters, and/or release of vapour emissions with the potential to adversely affect air quality or cause a health risk to local communities due to disposal of wastes at dump sites (non-engineered landfills) not designed or operated to the appropriate standards.

â€¢ Littering and health and safety risks associated with uncontrolled public access to wastes at landfill sites with inadequate security.

â€¢ Impairment of local air quality and increased health risks due to open burning of wastes.

â€¢ Contamination of soils, and surface or groundwater, potentially impacting on human health or ecosystems due to illegal dumping (‘fly-tipping’) of hazardous wastes (solid or liquid).

â€¢ Adverse effects on air quality and secondary impacts on the local community health due to improperly treated combustion emissions from incineration

2853a94f

CHAPTER FOUR

RESULTS AND ANALYSIS

4.1 Sampling Techniques

Random and unique sampling techniques were implemented in selecting three district zones within the six frontline oil producing districts in the western region. The chosen districts are Jomoro, Nzema East Municipal and Ellembele District. In each district/ town, three areas were randomly chosen. In each community, water samples were gathered from streams/rivers using random sampling techniques. In addition to the random sampling techniques, purposive sampling techniques were adopted in order to collect water samples from the Jubilee Field and areas where residents/fishermen thought had been polluted by the operations of the oil and gas companies. Table 1.0 below gives the list of communities where the water samples were gathered.

Table 1.0 List of communities where water samples were collected

S/No.

Name of community

District

Half Assini

Jomoro

Asanta – River Asanta

Ellembele

Ellembele Blay

Ellembele

River Ankobra – Axim

Nzema East

Rig – Jubilee Field

Nzema East

River Ankobra – Asanta

Ellembele

Sea Water – Half Assini

Jomoro

Axim – River Ankobra

Nzema East

River Ankobra – Axim

Nzema East

3.1 Sample collection, preparation and storage

Water samples were collected from rivers, streams, boreholes/wells and tap water in the study areas. 1.5L of the water samples were put into sampling containers that has been washed with 1:1 conc. HNO3 acid, double distilled water and fixed with identification labels. These samples were then stored in an ice – chest at a temperature of -40C and later conveyed to the Water Research Institute of Council for Scientific and Industrial Research (CSIR – WRI) for laboratory analysis. PH, turbidity and conductivity of the samples were determined using hand potable pH, turbidity and conductivity meters respectively on the field (AWWA, 1998). Two samples were collected from each sampling point. One was acidified with 10% nitric acid for the analysis of heavy metals whilst the other was used for the physicochemical analysis. The other sample was used for the physic – chemical analysis. In the laboratory, the acidified samples were filtered using Whatman’s no. 0.45µm filter paper. The 0.45µm membrane filter paper was used because the analyte of interest in the work is the total dissolved metals. The filtered samples and the unfiltered samples were stored in the refrigerator at -4oC for further analysis (APHA – AWWA, 1998).

3.2 Digestion of samples for the analysis of As, Fe, Mn, Cu, Pb, Cd and Zn

One hundred millilitres of the well – acidified water sample was mixed with 5ml conc. HNO3 and 5ml conc. H2SO4. This mixture was then heated until the volume was reduced to about 15 – 20ml. The digested sample was allowed to cool to room temperature. It was then filtered through Whatman’s 0.45µm filter paper. The final volume was adjusted to 100ml with double distilled water and stored for analysis (APHA – AWWA, 1998).

3.3 Analysis of samples for As, Fe, Cu, Mn, Cd, Pb and Zn

The method for the analysis of the water samples in this work was based on standard methods for analysis of heavy metals adopted by the US Environmental Protection Agency and American Water Works Association. The determination of the heavy metals in the samples was carried out by the Heavy Metals Laboratory of the Water Research Institute (WRI) of Council for Scientific and Industrial Research (CSIR). The concentrations of Fe, Cu, Mn, Cd, Pb and Zn were determined using flame AAS (Atomic Absorption Spectrophotometer) Perkin Elmer model 520 after double distilled water has been used to zero the instrument, the concentrations of Fe, Cu, Cd, Pb, Mn and Zn in the blank were also measured and then followed by the determination of the concentrations of Fe, Cu, Mn, Cd, Pb and Zn in the digested samples. The concentration of arsenic in the water samples were determined using flame AAS Perkin Elmer model 520 coupled with arsine gas generator. In the determination of arsenic concentrations in the water samples,

5ml of 0.5% NaBH4 and 5ml of 0.5M HCl were added to each of the digested sample to reduce all the arsenic in the samples to an arsine gas, in the arsine generator, which was coupled to the flame Perkin Elmer model 520.

3.4 Analysis of physico – chemical parameters

The physico-chemicals parameters including pH, turbidity, conductivity, apparent colour, sodium, potassium, calcium, magnesium, ammonium, chloride, sulphate, phosphate, nitrite, nitrate, total hardness (as CaCO3), total alkalinity (as CaCO3), calcium hardness (as CaCO3), magnesium hardness, fluoride, bicarbonates, carbonates, total suspended solids and total dissolved solids were also determine by the Potable Laboratory section of Water Research Institute of CSIR. The pHs of the samples were determined using Jennway pH meter model

3510, after the meter has been calibrated with pH buffer solutions of 4, 7 and 10.

The turbidity’s of the samples were also determined using Hach Turbidimeter model 2100P

whilst the electrical conductivities, total suspended solids and the total dissolved solids of the samples were also determined with Jennway Conductivity meter model 4520 (AWWA, 1998).

4.0 Mean results of the physico – chemicals parameters of the water samples

The mean results of pH, conductivity, colour, total dissolved solids, total suspended solids, sodium, potassium, calcium, magnesium and ammonium in the water samples from the study area is presented in table 1.1 below.

Table 1.1 Mean results of physico – chemical parameters in the water samples in the study area

Sampling Point

Parameters

Colour

Cond

–

µS/cm

TDS –

mg/L

TSS –

mg/L

Elembele 1 (River

Asanta Upstream)

7.23

1410

776

3.0

220

3.46

40.1

River Ankobra

-Axim

8.43

62000

34100

<1.0

8846

120

601 1312

Rig 1 (North of the

Rig)

8.40

2.50

63600

34980

<1.0

11248

132

441 1263

Elembele 2 (River

Asanta Downstream)

7.38

1371

754

4.0

216

3.24

48.1

20.6

Half Assini 1 (Sea

Water)

8.38

7.50

64900

35695

<1.00

13886

144

441 1433

Rig 4 (south of the

Rig)

7.33

7.50

64400

35420

<1.00

14680

138

521 1360

Rig 3 (East

of the Rig)

8.47

7.50

64200

35310

<1.0

12690

142

481 1409

Half Assini 2 (Sea

Water)

8.45

7.50

64800

35640

<1.0

11420

138

481 1409

Sea water –

Elembele

8.34

7.50

62000

34100

<1.0

11243

118

441 1215

Brackish water –

Elembele

8.38

7.50

62300

34265

<1.0

7654

132

521 1336

Rig 2 (West of the

Rig)

8.42

10.0

63100

34705

<1.0

12480

136

441 1239

Half Assini 3 (sea

Water)

7.30

64600

35530

<1.0

13482

152

481 1457

WHO Guideline

Value

6.5

–

8.5

–

1,000

–

200

150

*the bold figures exceeded WHO guideline values.

From table 1.1 above, it can be seen that pH of the water samples ranges from 7.33 to 8.47 pH units. These values falls in line with the WHO acceptable guideline values for pH for marine, brackish and natural resources. High conductivity values were recorded for water samples from sea water of Half Assini, Elembele and around the rig platform than water samples from rivers 1,371 µS/cm to 64,900 µS/cm. Electrical conductivity which is the ability of water to conduct electric current. The high electrical conductivity values recorded in this study means that there is high amount of cations and anions in the water samples.

Total dissolved solids (TDS) concentration in the study area ranged from 754 mg/L to 35,695 mg/L. TDS concentrations in most cases were generally higher than 1000 mg/l (WHO, 1993) and (WHO, 2006). Water samples with the highest TDS concentrations were sampled from river Ankobra, brackish or marine water in Elembele, Axim and Half Assini. High TDS in water may produce bad taste, odour and colour, and may also induce unfavourable physiological reactions in the consumer (Spellman and Drinan, 2000).

Sodium ion concentration ranged from 216 to 14,680 mg/L as shown in table 1.1 above. Sodium ion concentrations in the study areas were generally higher than the WHO guideline limit (200 mg/l). Consumption of water high in sodium is believed to increase one’s blood pressure, which may lead to cardiovascular diseases (Baird, 1999). High sodium in drinking water may give unacceptable taste (WHO, 2006).

Total hardness of the water samples from the study area ranged from 240.0 to 7,200 mg/L as shown in table 1.2 below. Water is termed to be soft, moderately hard, hard or very hard if total hardness range of 0-75 mg/l, 74-150 mg/l, 151-300 mg/l and >300 mg/l respectively are recorded (Lester & Birkett, 1999). Generally water samples from the sea by this classification are hard, as water samples from the rig area which are marine water samples, brackish water and water samples from rivers Ankobra and Asanta analysed in the study area respectively, recorded total hardness concentrations greater than 300 mg/l. Hardness gives an indication of the portability of water for drinking and domestic use (washing). A number of ecological and analytical epidemiological studies have shown a significant inverse relationship between hardness of drinking water and cardiovascular diseases (WHO, 2006).

Chloride concentration for water samples in the study area ranged from 315 to 25,212 mg/L as shown in table 1.2 below. Chloride concentration rivers Asanta and Ankobra were found to be above WHO guideline value (250 mg/L). Chloride level above the WHO guideline limit can give rise to detectable taste to water (WHO, 2006). Chloride concentrations in marine water samples are generally very high.

Sulphate ion concentration in the study area ranged from 54.1 to 394 mg/L. Generally sulphate ion concentration in water samples from the sea water are high, with the exception of one from Elembelle which recorded 57.5 mg/L, well above the WHO guideline of 250 mg/L. The high sulphate concentration recorded may be from the geological formation (Birimian rocks) of the area or other water bodies which drains into the sea. High levels of sulphate in drinking water have been found to cause gastrointestinal effects in human. Nitrate-N levels recorded during the study period ranged from 0.01 to 1.10 mg/L as shown in table 1.1 below. Nitrate-N levels in the study areas were generally lower than the recommended WHO guideline (10 mg/L). High nitrate-nitrogen levels in water samples are as a result of run-offs from nearby agricultural lands

and also due to the unsanitary and unhygienic conditions prevailing around these water bodies. High levels of nitrate ion in drinking water may cause methemoglobinemia in newborn infants, as well as in adults with particular enzyme deficiency (Baird, 1999). Phosphate ion concentration ranged from 0.014 to 0.132 mg/L as shown in table 1.2 below.

Table 1.2 Mean results of physico – chemical parameters in the water samples in the study areas

N Sampling Point

Parameters

Turb/ TU

Cl-/

mg/L

SO42-/

mg/L

PO4-P/

mg/L

NO2-N/

mg/L

NO3-N/

mg/L

Tot. Hard/

mg/L

Elembele 1 (River

Asanta Upstream)

1.54

54.1

57.5

0.121

2.48

1.10

240

R i v e r Ankobra

-Axim

1.82

342

0.118

0.245

0.415

6,900

Rig 1 (North of the

Rig)

1.46

20,845

329

0.014

0.026

0.240

6,300

Elembele 2 (River

Asanta

Downstream)

2.63

315

329

0.132

0.232

0.513

205

Half Assini 1 (Sea

Water)

4.05

24,517

335

0.024

0.822

0.001

7,000

Rig 4 (south of the

Rig)

2.20

25,512

335

0.022

0.079

0.400

6,900

Rig 3 (East

of the Rig)

2.47

16,576

343

0.022

0.457

0.300

7,000

Half Assini 2 (Sea

Water)

2.83

20,943

370

0.029

0.310

7.000

Sea water –

Elembele

1.97

19,356

394

0.054

0.352

6,800

Brackish water –

Elembele

2.21

15,286

343

0.090

0.300

6,100

Rig 2 (West of the

Rig)

2.12

21,242

360

0.031

0.233

0.250

6,200

Half Assini 3 (sea

Water)

2.81

23,227

340

0.082

0.274

0.283

7,200

W H O G u i d e l i n e

Value

250

–

1.0

500

*the bold figures exceeded WHO guideline values.

The mean levels of heavy metals such as manganese, arsenic, iron, zinc, lead, cadmium, copper and oil/grease concentrations in the water samples from the study area is presented in table 1.3 below.

Table 1.3 Mean levels of manganese, arsenic, iron, copper, cadmium, zinc and oil/grease in the water samples from the study area.

Sampling point

Concentration in mg/L

Elembele 1 (River

Asanta Upstream)

0.040

0.772

0.045

0.004

0.005

0.001

0.020

River Ankobra -Axim

0.051

0.657

0.032

0.092

0.414

0.001

0.065

Rig 1 (North of the

Rig)

0.048

0.443

0.091

0.105

0.286

0.001

0.059

Elembele 2 (River

Asanta Downstream)

0.087

0.754

0.007

0.101

0.005

0.001

0.078

Half Assini 1 (Sea

Water)

0.059

0.684

0.048

0.096

0.184

0.001

0.070

Rig 4 (south of the

Rig)

0.058

0.690

0.047

0.101

0.259

0.001

0.053

Rig 3 (East of the Rig)

0.049

0.539

0.048

0.100

0.471

0.001

0.065

Half Assini 2 (Sea

Water)

0.054

0.563

0.048

0.089

0.216

0.001

0.020

Sea water – Elembele

0.521

1.15

0.057

0.002

0.372

0.001

0.059

B r a c k i s h w a t e r –

Elembele

0.059

0.754

0.011

0.004

0.477

0.001

0.034

Rig 2 (West of the

Rig)

0.049

0.435

0.034

0.092

0.312

0.001

0.072

Half Assini 3 (sea

Water)

0.063

0.908

0.080

0.116

0.310

0.001

0.073

WHO Guideline

Value

0.4

0.3

3.0

0.05

0.015

0.01

2.0

G E P A G u i d e l i n e

value

–

1.0

–

*the bold figures exceeded either WHO or GEPA permissible guideline values.

From table 1.3 above, it can be seen that the concentration of manganese ranged from 0.040 to

0.087 mg/L. Manganese is a neurotoxin and as such exposure to elevated levels of it via oral ingestion poses significant health hazard. Manganese concentration in the water samples in the study area were found to be below the WHO permissible value of 0.40 mg/L.

Total iron concentration in the study area ranged from 0.435 to 1.15 mg/L . The prevalence of iron levels above 0.3 mg/l was noticeable in all the water samples collected from the study area. The presence of high iron could be as a result of

Order Now