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.
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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.
Figure : Coastal line of Ghana
Figure : Ghana’s offshore oil fields
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.
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.
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:
Results and Analysis
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.
Figure : Location of Jubilee Field
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.
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.
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:
â€¢ round sardinella;
â€¢ flat sardinella;
â€¢ European anchovy; and
â€¢ chub mackerel.
Large pelagic seafood stocks off the shore of Ghana consist of seafood and billfish. These varieties are migratory and take up the outer lining position ocean of the whole exotic and sub-tropical Ocean. They are essential varieties in the environment as both should and feed for sharks, other seafood and sea animals as well as offering an essential commercial resource for industrial fisheries. The seafood varieties are skipjack tuna; yellowfin tuna; and bigeye seafood. The billfish varieties happen in much lower figures and comprise swordfish; Ocean blue marlin; and Ocean sailfish.
Trawl surveys have proven that demersal seafood are extensive on the navigator shelf along the whole length of the Ghanaian coastline. The demersal varieties that are most essential over the counter (in terms of capture volumes) are cassava croaker, bigeye grunt, red pandora, Angola dentex , Congo dentex and Western Africa goatfish.
Over 180 species of fish are believed to take up the deep sea, including 51 different species that are associated with the bottom and a further 106 are listed as bathypelagic (1000 to 4000m). The remaining species are usually regarded to take up depths to 1000 m but may venture into further water during part of their lifecycle. A total of 89 species are likely to be discovered in Ghanaian water bodies within the depth range in the Jubilee field (1,100 and 1,700m).
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.
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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.
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.
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
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
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.
under Ghanaian legislation and/or international conventions.
Listed as rare, threatened
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).
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). (Boe
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