辽河油田欢50块表面活性剂/碱驱油研究

Alkaline/surfactant flooding in Huan 50 block of Huanxiling field.

辽河油田欢５０ 块为低渗透油藏，孔隙度小，岩性致密，地层温度高，原油含蜡量高，凝固点高，导致生产时产量下降快，产能低，采出程度低。针对生产中的问题，进行了碱／ 表面活性剂复合驱提高原油采收率的研究。通过研究复合体系溶液与欢５０ 块原油的界面张力、复合体系溶液的长期热稳定性，从７ 种表面活性剂中筛选出既能降低油水界面张力，又能适应该油藏９９℃高温的表面活性剂，并研究了该表面活性剂和碱形成的复合体系在欢５０ 块油砂上的吸附以及复合体系溶液驱油效率。该体系在９９ ℃时能大幅度降低欢５０块原油的油水界面张力（达０．０１ ｍＮ／ｍ 以下） ， 并具有很高的驱替效率，水驱后注入复合体系段塞，平均采收率达６５．２４ ％ ，相对于水驱，提高采收率平均为１８．４％ 。并运用核磁共振成像技术研究复合体系溶液的驱油机理，复合体系注入前后核磁共振成像结果表明，复合驱能提高驱替效率，在复合体系前缘形成富集油带，对进一步采出水驱剩余油明显有效。

Huan 50 block is a low permeability and low porosity field with high formation temperature. The sand is tightly cemented. The oil in this field is of high paraffin and has high solidification temperature. The oil production is low and declines fast, resulting a very low cumulative recovery. A EOR study on combination flooding of alkaline/surfactant is carried out. Through the research of the interfacial tension (between the alkaline/surfactant combination system and oil) and the long term thermal stability, a suitable surfactant for this high temperature is selected from seven surfactant. The absorption of the combination (surfactant and alkaline) on sands and the enhanced oil recovery in sandstone cores of Huan 50 block are studied. This combination system can reduce the IFT greatly to 0.01mN/m and is of high effect in driving oil. After water flooding, a slug of combination system is injected, the average oil recovery of four cores is 65.24% and the average enhanced oil recovery is 18.4%. Finally the nuclear magnetic resonance (NMR) technology is applied in alkaline/surfactant flooding. Before and after injection the combination system the NMR pictures were taken. In NMR picture a rich oil region was seen which indicates that this alkaline/surfactant is effective.