注水井转抽技术研究及其应用

The Research and Application of the Technology of Injection Well Converting into Production Well in the Low Permeability Oilfield

低渗透油田采用水驱方法效果较差,最终采收率只有20%。为此,开展了注水井转抽现场试验研究。根据室内实验和水驱油渗流机理,阐述了油田注水井微观出油机理和宏观出油机理,应用理论计算分析和数值方法,定量分析认为,影响注水井转抽效果的主要因素有启动压力、毛管力、到断层的距离、孤立砂体有效厚度等。通过室内核磁共振实验和孔隙结构分析,阐明了换向驱油(注水井转抽)可以提高采收率,在此基础上,从总结矿场试验资料入手,通过地质基础和开发特征研究,提出了适合注水井转抽的地质条件:转抽的注水井要取得较好效果,则注水井到断层的距离应大于50m,或该井钻遇孤立的中高渗透砂体且有效厚度应大于3m。

The effect of water flooding in the low-permeability oilfield was not satisfied with only 20% of the ultimate recovery effficiency.Therefore ,field test was carried out on the injection well converting to the production well.Based on the laboratory tests and water-drive mechanism,microscopic and macroscopic oil dis- placement mechanisms of the injection well were analyzed.After theoretical and numerical methods were applied,the main factors influencing the effect of the injection well converting to the production well included actuating pressure ,capillary pressure ,distance to the fault,effective thickness of isolated sandbody and so on. Through nuclear-magnetic-resonance experiment and pore-structure analyses,it was known that oil displacement of the production well converted by the injection well may enhance oil recovery.Based on the field test data of geology and production,the suitable geological conditions for the injection well converting into the production well were ：the distance between the injection well to the fault should be more than 50m,or iso- lated mid-high-permeability sandbody with effective thickness more than three meters may be drilled by this injection well.