Microbial Water Diversion Technology for Enhanced Oil Recovery in Sandstone and Carbonate Reservoirs

Natural bacteria increase oil production GOE-IP in collaboration with UNI Research CIPR and relevant oilcompanies, has proven mechanisms to shut of waterbreakthroughs in heavily waterflooded chalk/carbonate- and sandstone reservoirs, on laboratory scale. The project is heavily funded by the Norwegian Research Council. The project is conducted over a period of 3,5 years and will be fully finalized during Q 1, 2018. Based on current results pilots are under planning for execution. If the pilots conclude expected outcome, the technology will turn into commercial use directly after any finalization of pilots in 2018. Modelled outcome estimates 2-10 % of total volume predicted in a reservoir (STOOIP). Problem and method The pressure that enables us to drive oil upwards from the reservoir decreases over time. Therefore, water is injected in the reservoir, to maintain the pressure and to continue the oil recovery. After the injection, the water forms small rivers and canals in the oil stocks, as oil continues to flow to the production well. Eventually the water finds the path of least resistance trough the stocks, and into the production well. At that point the recovery process is stopped, although there is more oil in the reservoir. As such, scientists all over the world are conducting research on methods to block the water canals before they reach the production well, to increase oil recovery. Statoil is for instance currently testing to plug them with sodium silicate. Greening effects The challenge when plugging or blocking water, is that the water will start creating new canals, trying to find their way around the plug. Just as if you dig out a river around a sandcastle; when you try to seal it, the water finds new paths through the sand. The silicate that is used in Statoil?s project is static, which means that the plug will remain where it is set. Hence the effect will diminish as the water finds its way around the plug. GOE-IPs method is vibrant and dynamic. GOE-IP uses natural bacteria to plug the water, and the bacteria will continue to plug new rivers and channels, as the water creates them. In order for the bacteria to do this, it needs to be continuously growing. Adding nutrition form trees to the reservoir, will ensure bacterial growth. GOE-IPs method creates a large new market for the forest industry, and has several additional greening effects. Value for society In parallel, the project has tested relevant sources for the technology for commercial use. Raw material form Norske Skog shows to be relevant for use in an additional production process and used as a central building block with the specific chemical mechanisms required. If the technology was used for relevant fields at the Norwegian Continental Shelf today, the need for raw material supply would exceed the total production at Norske Skog 3 times. Injection of nutrients from wood is considered carbon storage, without danger for leakage. It is the nature of this concept to preserve carbon subsurface in other form then gas. De final tests and research show that the technology in action will interfere with the microbial systems found any time in a reservoir. To avoid this a selective media needs to be developed. The existing solutions known will however lead to negative environmental issues of unknown magnitude. The model organism used for testing shows negative preferences to survive over time where oil is present. Summarized, it will be difficult to control organisms not naturally found in the reservoir to be controlled to the level needed for shutting of water bearing zones.

The MORE-SAC project concerns a new technology for Enhanced Oil Recovery using Microbial Selective Plugging (MSP) and Water Diversion, aiming at increasing tail end oil production from mature reserves. Oil reservoirs have heterogeneous permeability and although pressure support in the form of water or water-alternating-gas injection will drive more oil to the producing wellhead, and selective flow paths will usually form. GOE-IP AS is currently developing a new concept for selectively blocking preferential flow paths in sandstone reservoirs. The concept is to use specific microbial cultures exogenous to the reservoir environment to establish a permeable plug directly in the flow path of the water injected into oil reservoirs (patent publication number WO2012164285A1). The bacterial culture behaves in such a way that it will only grow where there is a flow of nutrients but with little or no oil present. The bacterial growth and properties will form a restriction that reduces the conductivity of the high permeability water channel. This restriction creates new reservoir volumes to be contacted by injection water and will result in acceleration of oil production and increase in oil reserves. As new flow path develops, the bacteria will follow and eventually grow and reduce connectivity in the new channels (adaptive behaviour). This adaptive behaviour should result in higher oil recovery than can be assigned to chemical methods. These bacteria can also aid in an innovative technology development for plugging of fractures in carbonate oil reservoirs-Particle Fracture Blocking (PFB). The role of the bacteria is to reduce the viscosity of a carrier suspension such that the particles contained in the slug can be compressed forming an impermeable plug capable of withstanding significant differential pressure. Plugging of fractures enable forced imbibition or fracking of reservoir matrix allowing a higher oil production rates and recovery.