Research on the Mechanism of Decompression and Augmented Injection during Waterflooding Development in Low Permeability Reservoirs

ABSTRACT

Developing low permeability reservoirs becomes more and more important to the sustainable energy development in China and the waterflooding development is the common mode. But with the oilfield development, water injection well has exposed some problems gradually, such as the injection pressure increases, water injection rate decreases and so on. Based on this situation, scale inhibitor, corrosion inhibitor and other additives are added in injection water continually, which increases the development cost to a large extent.

In order to develop low permeability reservoirs better and more economical, we proposed a novel decompression and augmented injection technology by manufacturing a novel surfactant FS-01, which could change the wettability of the rock surface and has the features of low free surface energy, low interfacial tension, emulsifying and so on. The decompression and augmented injection mechanism is discussed by measuring the contact angle, SEM (scanning electron microscope), EDX (energy dispersive X-ray), oil-water relative permeability test and so on. After the core surface treated by FS-01, the contact angle of crude oil and the core surface increases from 35.35°to 85.7°, which has perfect wettability reversal function. After the successful application in well HJS112-21 in ShengLi oilfield, it is proved that the new technology has well decompression and augmented injection function.

Keywords:

Waterflooding, decompression, augmented injection, surfactant, rock surface property, low permeability reservoir.