After the application of a non?ionic polyether clear water agent in an oilfield in the Bohai Sea,the difficulty of dewatering crude oil in the downstream terminal treatment plant increased,and the water content of the outgoing crude oil frequently exceeded the standard.The Effect of nonionic polyether water clarifier on crude oil dehydration was researched,the reasons of difficulty in dewatering were analysed,and the emulsion could not be treated by conventional polyether demulsifier.Polyamines were synthesised from dimethylamine,dodecyl dimethyl tertiary amine and epichlorohydrin,while polyethylene?polyamines were used as cross?linking agents to synthesise polyamine copolymer emulsion breakers.The emulsion breaker can reduce the water content of the external crude oil to less than 0.5% at a concentration of 80 mg/L,and reduce the static dewatering time of the crude oil from more than 120 h to less than 48 h.This effectively solves the problem of excessive water content in the external crude oil of the terminal treatment plant.

This paper investigated fluid properties of the reservoir,composition of the reservoir rock,and microbial growth in a Bohai oilfield,where the concentration of hydrogen sulfide continued to rise. The results indicate that biogenic origin is the main reason of hydrogen sulfide.In order to solve the problem that hydrogen sulfide content exceeds standard value,evaluation experiments of different types of desulfurizers were carried out to investigate the effects of mass concentration of desulfurizer,pH,water content and desulfurization time on desulfurization effect. The results show that 1, 3, 5?triazine derivative desulfurizer TL?13 shows the highest efficiency of desulfurizing.The concentration of hydrogen sulfide in turbine fuel gas decrease from 150 to 8 μg/g after desulfurization by desulfurizer TL?13,and reaches the standard of turbine fuel gas.This paper provided technical support and practical experience for treatment of hydrogen sulfide in offshore oilfield.