TECHINICAL FILE: Lake Malawi Petroleum Exploration
By Grain Wyson Phillip Malunga – FIMMM Mining and Environmental Management Expert
Lake Malawi has potential to host petroleum due to its geological and structural setting. Recent grant of oil exploration licences to blocks in the lake has raised controversial remarks and outcry on effect of environmental sensitivity and sustainable livelihood of the people that depend on this natural resource. The lake is taken as world heritage site and offers a very rich biodiversity. Fisheries sector offers over 60% of Malawi’s protein requirements. At the same time Malawi relies on fuel imports through expensive mode of transportation and geopolitics.
The paper highlights stages of exploration and production that need to be followed while promoting sensible dialogue and weighing on the positive and negative effects of oil and gas exploration and production.
Malawi has high potential for discovery of petroleum (crude oil and natural gas). On average, crude oil contains about 84% carbon; 14% hydrogen; 1 to 3% sulphur; and less than 1% of nitrogen, oxygen, metals and salts.Potential areas have been identified as thick sediments in Lake Malawi, Chitipa, Vwaza, Mangochi –Phalombe Area and the Shire Valley. The host rocks could be sandstone and carbonate rocks.
Structural analysis of the Lake has also proved sedimentary basins in Karonga, Nkhata Bay and Nkhota Kota. Geoscientists have called these basins as Karonga, Usisya, Mbamba, Bandawe, Matengula and Mtakataka respectively. The thickness of the sediments is over 4000 metres, well above oil forming window.
Recent outcry by onshore communities and civil society groups has highlighted the economic and environmental sensitivity of undertaking exploratory and development activities in the lake. Wrong and correct perceptions on petroleum exploration and drilling in Lake Malawi have been advanced. The paper tries to put all these into perspective.
2.0 FIELD GEOLOGICAL ASSSESSMENT
Petroleum exploration in Malawi is granted after an Environment and Social Impact Assessment (ESIA) has been done approved by the Department of Environmental Affairs. Areas of focus in the ESIA is the impact of exploration activities in the lake and onshore areas.
The main activities are, geological and geophysical surveys, geological mapping and sampling (rock, soil, water and gas), and geophysical surveys (magnetic, gravimetric and seismic). Observation for oil seepage is also done.
The ESIA identifies environmentally sensitive areas, protected sites and heritage sites. These areas are exempted from exploration. Such areas in Lake Malawi include island sites, national parks where aquatic and flora diversity has been confirmed.
Decisions have been made to undertake exploration activities onshore and airborne surveys were undertaken to minimise negative environmental impacts associated with the exploration programs. It must be noted that community sensitization meetings and scoping are undertaken before identification of impacts associated with this program.
3.0 EXPLORATORY DRILLING OF PROMISING AREAS
Interpretation of airborne geophysical survey, structural analysis and results of geological and geophysical sampling culminates into target identification for exploratory drilling (wild cats). Once the targets have been identified, another ESIA is undertaken to identify environmental impact assessment related with the following;
- Human, socio-economic and cultural that includes effect on Land use pattern, Immigration (population increase), Change in life style (employment, income differentials and inflation), change in culture and heritage e.g. foreign cultural influence, practices and beliefs, availability of goods and services, e.g. introduction of electricity, water, education, health facilities that will also benefit local communities, conflict between development and protection, aesthetics or unsightly existence of noisy facilities and effect of transportation systems that include dust and accidents.
- Atmospheric impacts arising from oil and gas emissions, airborne particulates from burning sources e.g. well testing accessibility.
- Aquatic impacts coming from produced water, drilling fluids and treatment chemicals, spills and leakages. These need to be contained.
- Onshore impacts may include physical disturbance from construction that influence deforestation and soil erosion and contamination that may arise from spillage, leakage and waste disposal.
- Ecosystem impacts arise through loss of habitat, changes in species composition, loss of microbial life and anthropogenic activities that may affect the degree of hunting, fishing and bush fires.
- Potential emergences both off shore and onshore include spillage of oil and gas, chemicals and hazardous material, well and gas blow out, explosions, fire, natural disasters such as lightening and earthquakes as drilling equipment may act as lightening rod while earthquakes may affect drilling platforms.
4.0 DEVELOPMENT AND PRODUCTION
This stage is undertaken when exploration drilling has hit oil or gas. Exploration holes turn into development wells when oil or gas have been hit. More development wells are drilled and the main worry is oil spills that may impact the environment in the following ways:
4.1 Physical smothering of organisms arising from crude oil especially in the lake Organisms lose ability to respire, feed and have thermoregulation.
4.2 Chemical toxicity may arise if lighter chemical components are ingested by organisms. Organs, tissues and cells may have lethal toxic effects.
4.3 Ecological changes should be guarded against in order to avoid alteration of ecosystem dynamics. This is true when other species undertake similar functions of other affected species.
4.4 Loss of shelter or habitat through oiling or clean-up operations may occur.
In case of oil spills in water, use of booms and sorbent materials is the standard procedure for containing them. Sometimes directional drilling is preferred in highly sensitive areas such as Lake Malawi.
Any development project has both positive and negative impacts. Should positive impacts outweigh negative impacts then it is worth undertaking such activity. Impacts of Lake Malawi drilling project need to be looked at using thorough analysis of potential impacts of seismic survey using compressed air and accidental oil spillage arising from exploration drilling and development wells.
Stakeholder consensus needs to be reached based on scientific analysis and not fear. Heritage sites and protected areas need to be respected.
Onshore exploration and drilling should be the first option and should need be directional drilling should be the first choice for exploration under Lake Malawi.
ESIA at all stages of development needs to be undertaken and stakeholder consultation is a necessity.
- Grammer G. M. 2008. Geology and Petroleum. Western Michigan University. Power Point Presentation.
- International Continental Scientific Drilling Program.2004. Paleoclimate and Sedimentary Basins. Power Point Presentation.
- International Tanker Owners Pollution Federation. 2012. Effects of Oil Pollution on Fisheries and Mariculture. Technical Information Paper.
- Malunga G. W. P. 2015. Oil and Gas Potential in Malawi. Technical Review. Mining Review Issue Number 26.
This piece was initially published in Malawi’s Mining & Trade Review Issue Number 54 (October 2017).