Chemical Injection Method
GENERAL
The injection of various chemicals, usually as dilute solutions, have been used to improve oil recovery. Injection of alkaline or caustic solutions into reservoirs with oil that has organic acids naturally occurring in the oil will result in the production of soap that may lower the interfacial tension enough to increase production. Injection of a dilute solution of a water soluble polymer to increase the viscosity of the injected water can increase the amount of oil recovered in some formations. Dilute solutions of surfactants such as petroleum sulfonates or biosurfactants such as rhamnolipids may be injected to lower the interfacial tension or capillary pressure that impedes oil droplets from moving through a reservoir. Special formulations of oil water and surfactant, microemulsions, can be particularly effective in this. Application of these methods is usually limited by the cost of the chemicals and their adsorption and loss onto the rock of the oil containing formation. In all of these methods the chemicals are injected into several wells and the production occurs in other nearby wells.
ENHANCED OIL RECOVERY WITH CHEMICALS
The difficulty wth "Heavy Oil" is that it will not fow out of the reservoir rock due to its high viscosity. Heavy oil resembles honey, or is even solidified, but in either case it is effectively "stuck in place". Heavy oil is defined as oil with an API gravity less than 20, amd oil with an API gravity less than 10 is called "Extra Heavy".
Most experts agree that oil becomes "heavy" as a result of biodegradation where the oil has been exposed to the atmosphere and the lighter components have evaporated, or where the oil has been in contact with bacteria rich water and the lighter oil components have been consumed in the reservoir. In order to produce these heavy oils two things have to happen:
a) The oil must be heated and liquified
b) Pressure must be created to drive the oil out of the reservoir
One of the best methods and also one of the main focuses of the Blue Water Project to accomplish these two necessary conditions is to inject a combination of reactive chemicals into the reservoir formations in a central "injection" well. These chemicals are pumped down the well in separate pipes and through a packer where they mix together at the bottom of the hole and adjacent to the reservoir formation. When the chemicals mix together a significant "exothermic reaction" occurs that generates large amounts of heat and gas that liquifies the heavy oil and drives it out t the "recovery" wells.
This system can be repeated in 40 acre units until the entire reservoir area is covered. It is an extremly efficient method to recover heavy oil, and results in very high oil recovery rates.
