Abstract：
In the late stage of oilfield development, in order to cope with problems such as a sharp increase in water cut, low oilfield geological permeability, and heterogeneity, oilfield foam flooding technology was developed and gradually entered field applications. A high-efficiency foaming agent is one of the key factors that increases oil recovery and affects the success of foam flooding technology. This work aimed to prepare high-efficiency, oil-resistant and temperature-resistant foaming agents that can prevent chromatographic separation. We prepared a series of Polyoxyethylene Ether Naphthalene Sulfonates(PENS) by using naphthalene, concentrated sulfuricacid, and ethylene oxide with different chain-length alkyl groups. In addition, we investigated the effect of the chain length of the alkyl groups on the product properties. The surface tension of the product, emulsification performance, foam performance in saline water and laboratory core oil displacement performance are also studied. When the chain length of the linear alkyl group was ten carbons, the surface tension was relatively high; when the chain length was greater than ten carbons, the surface tension between the products was not obviously different. The product with a fourteen-carbon linear alkyl group had the lowest surface tension and the minimum critical micelle concentration. Similarly, emulsifying performance results show that when the chain length was greater than ten carbons, the products had good emulsifying properties. The product with fourteen-carbon linear alkyl group showed the best emulsion stability. The
foam performance test results indicated that the fourteen-carbon system has the best foaming ratio and liquid drainage half-life, so its
high-temperature foam performance is the best. Based on the above findings, we investigated the properties of polyoxyethylene ether
naphthalene sulfonates with fourteen-carbon linear alkyl group (PENS-14C), including adsorption resistance, oil resistance, corrosivity,
interfacial tension with the crude oil of the targeted reservoir, and the laboratory displacement ability in the cores. All the experimental
results demonstrated that PENS-14C had good adsorption resistance and oil resistance. Before and after adsorption, the foam
performance of the foaming system did not decrease significantly; and with an increase in oil content, the decrease of foam performance
was smaller. Meanwhile, its corrosivity also reached the standard. In addition, PENS-14C effectively reduced the oil-water interfacial
tension of the target crude oil. The final laboratory core flooding experiment results showed that the foaming agent can increase the
recovery rate by 21.0
%
, which fully meets the performance requirements of high-temperature reservoir foam oil displacement agents.
Key words：sodium polyoxyethylene ether naphthalene sulfonate; surface tension; emulsifying; foaming property; adsorption resistance; oil resistance; corrosivity; interfacial tension; displacement ability
Corresponding Authors：yjy_wanght@petrochina.com.cn
Cite this article：WANG Hongtao, Feng Lijuan, HE Meng, ZHANG Yuzhen, Guo Dan, ZENG Qingqiao, YANG Lutao, ZHANG Luxia. Preparation and properties of sodium polyoxyethylene ether naphthalene sulfonate with different chain-length alkyl groups. Petroleum Science Bulletin, 2020, 04: 587-596.
