PetroSA wants to explore the possibility of hydraulic fracturing to improve the productivity of three of the development wells currently being drilled 110km offshore of Mossel Bay.
In an advertisement that recently appeared in Die Burger, environmental assessment consultant WorleyParsons and PetroSA expressed their intention to amend their existing production right and Environmental Authorisation and Environmental Management Programme for the F-O field development. The application for amendment is to allow for well stimulation (hydraulic fracturing) ‘to improve productivity of three of the development wells currently being drilled 110km offshore of Mossel Bay’.
According to the advertisement, PetroSA has been exempted from submitting a scoping report, as the application is an amendment of an existing Environmental Authorisation.
WorleyParsons is conducting an Environmental Impact Assessment (EIA) and will assess a number of identified key environmental and social impacts that such project might have.
PetroSA confirmed that the intended project is part of Project Ikhwezi.
“It is of utmost importance to note that at this time, the Final Investment Decision has not yet been made and will be taken on the basis of the engineering work, risk assessments and results of the Environment work being completed,” the company stated in reaction to media queries.
The proposed fracturing process
After drilling and completing the already approved wells, the formation would be fractured to increase the reservoir’s productivity. Fracking increases the amount of exposure the well has to the reservoir and provides a channel through which gas can flow easily into the well. This is according to the information document, available on https://africaenviro.worleyparsons.com.
There are 10 steps to the hydraulic fracturing process. These would include a hydraulic fracturing vessel carrying proppant and hydraulic fracturing fluid from the Mossel Bay harbour to the F-O Field; the hydraulic fracturing fluid being pumped from the vessel into the well; and excessive proppant and hydraulic fracturing fluid components possibly being discharged overboard.
It is estimated that the vessel may have to make about five trips per well between the port and the F-O Field, due to its limited carrying capacity.
Potential impacts identified are, most noteworthy:
- Impacts on the seabed: Possible changes to the geology underneath the seabed due to the deposition or infilling of proppant during fracturing.
- Water availability: Increased consumption from municipal supply for the production of hydraulic fluid.
- Water quality, animals and plants: The noise from the vessel may disturb marine mammals. The discharge from the hydraulic fracturing vessel may impact the plankton, fish and other organisms living in the water column.
- Waste management: Various types of waste will be generated by the project, which should adversely impact the natural environment if not handled and disposed of appropriately.
- Social impact: The possible enhancement of production from wells may sustain gas feedstock for the GTL refinery with associated employment and benefits.
- Non-routine events and accidents: Accidental event such as a well blow-out, vessel collision or chemical spill may result in water and sediment pollution and result in secondary impacts to fauna and flora. There is also a risk of seismic events.
According to the information document, the hydraulic fracturing fluid to be used comprises of 99.5% water and sand; and the other 0.5% comprising of acid, fraction reducer, surfactant, gelling agent, scale inhibitor, pH adjusting agent, breaker, crosslinker, iron control, corrosion inhibitor, antibacterial agent and clay stabiliser.
If the application is turned down, PetroSA will continue with its F-O Field development as per the existing Environmental Authorisation. This will result in a shortened life expectancy of the gas-to-liquid refinery if the wells do not produce as expected.
By Mari Scott. Source: Mossel Bay Advertiser
This model explains hydraulic fracturing under the seabed.