Compatibility Of Water Injection In Low Permeability Reservoir Of Sea B Oilfield And Study On Pressure Increasing

Waterflooding is the main development model of the offshore low permeability reservoir. Because of the actual problems such as increasing injection pressure and decreasing injection rate that exist in actual waterflooding exploitation, there is a urgent need for designing high and low limit to the quality indexes of the compatible injection water and for the research on decompression and augmented injection, in order to lift the injection well plugging and extend the effective period of waterflooding.This paper used the Shahejie low permeability formation of the offshore oilfield B as an example. Firstly, this paper analyzed the physical properties and current water quality control situation of the oilfield B. By focusing on the analysis of the reservoir damaging factors during water flooding such as the content of suspended particles, the diameter of suspended particles, emulsified oil and sensitive minerals, a series of comprehensive and systematical researching experiments on the compatibility has been carried out. And based on the results of the indoor experiments, this paper proposed a compatible water quality criterion scheme thafs feasible to Shahejie formation.. Then, the paper used the designed compatible water quality criterion to predict the changing tendency of different injection well’s water absorbing ability, and found that the injection’s half-life of each well was extended. In order to further extend the augmented injection water injection cycle, a novel and effective technique for improving oil production has been invented. By combining the mechanism of the two currently frequently used augmented injection techniques for low permeability reservoir including surfactant flooding and active nano-materials flooding, this technique blended two kinds of augmented injection agents (the gemini surfactant MT-01and the nano-emulsion NPS-L), in order to get a composite system used for the decompression and augmented injection of the injection well. This composite system is able to reach ultra-low interfacial tension and has an excellent stability, a certain anti-clay swelling ability as well as a great wettability. Finally, through conducting the indoor core flooding experiment, it’s verified that, compared with both gemini surfactant MT-01’s and nano-emulsion NPS-L’s independent effect on the performance of decompression and augmented injection, the composite system had a more positive effect on decompression and augmented injection.This paper eventually obtained the injection water quality criterion as well as the decompression and augmented injection technique which are adaptable to the low permeability reservoir. The result has a practical value, because it provides the basic experimental foundation for guiding future’s exploitation of the low permeability reservoir of the offshore oilfield B or the any other low permeability reservoir with similar physical properties.