微生物对岩石表面及地层流体性质的影响

Laboratory Studies of Microbial Action on Rock Surface and Fluids in Reservoir Formations

用测接触角的方法研究了 6株微生物菌与 3种不同性质岩石作用后的接触角变化 ,分析了接触角变化对岩石润湿性、水驱油毛管力、剩余油粘附功及提高采收率的影响 ,实验研究了微生物作用后原油烃组分、原油粘度和油水间界面张力的变化。研究表明 ,微生物作用可明显改变岩石表面润湿性 ,使接触角降低 ,接触角改变大小与微生物种类、作用时间、岩性有关 ;微生物作用可显著改变水驱油毛管力 ,减少剩余油粘附功 ,使剩余油易于剥落、聚集 ,加速其在毛细管中的流动 ;微生物作用可降低原油高碳链烃含量 ,降低原油粘度 ;微生物作用可增加水中有机酸含量 ,降低水的表面张力和油水间界面张力。

The variation in contact angles of water droplets on the rock surfaces treated by six bacterial strains notated as A—F is determined experimentally. It is shown that the wettability of(the contact angle on) the biotreated glass surface changes dramatically and fast and that of/on the biotreated limeston and quartz surfaces—moderately. Of six strains tested strain B is the most effective in lowering contact angles. The capillary driving force, P c, and cohesion work of oil phase, W o, are estimated from the contact angle determinations and significant increase in P c values and notable decrease in W o values are observed for limestone and glass like rock after biotreating. It is also shown experimentally that the hydrocarbon carbon number distribution curve displaces to direction of lower carbon number after the crude oil having been treated by a bacterial strain and some lower(C 2—C 5) carboxylic acids are identified in the water flown through the biotreated core.