短短芽孢杆菌和蜡状芽孢杆菌采油机理及其在大庆特低渗透油藏的应用

The recovery mechanism and application of Brevibacillus brevis and Bacillus cereus in extra-low permeability reservoir of Daqing

针对大庆外围朝阳沟油田储集层和油水特性,筛选出短短芽孢杆菌(Brevibacillus brevis)和蜡状芽孢杆菌(Bacilluscereus)作为采油菌种。实验结果表明,实验菌株作用原油烃时只降解高碳链(C20以上)饱和烷烃,降解途径以氧化降解为主,代谢产物以饱和烷基酸为主,没有低碳饱和烷烃的生成。实验菌种性能评价结果表明:微生物作用后界面张力下降50%左右,产生多种有机酸;微生物可选择性降解原油中某些中—高碳数烷烃,使原油中的长链烷烃含量相对减少,短链烃含量相对增加,原油黏度下降40%左右,含蜡量、含胶量下降,流变性得到改善。物理模拟驱油实验表明微生物提高采收率幅度可达到6.7%。应用短短芽孢杆菌和蜡状芽孢杆菌等菌种在大庆朝阳沟特低渗透油田开展的微生物单井吞吐试验和微生物驱油矿场试验取得了理想效果。

In view of oil and water properties and reservoirs characteristics of Chaoyanggou oilfield on the periphery of Daqing, Brevibacillus brevis and Bacillus cereus were screened as the bacterial groups of bacterial oil recovery. When the bacterium act on hydrocarbon, only long-chain paraffin hydrocarbon molecules （over C20 ） are degraded, mainly by oxidative degradation and the metabolic product is dominated by saturated alkyl acid, with no short-chain hydrocarbon molecules being generated. The interracial tension is decreased by about 50% and many kinds of organic acids being generated; the bacterium can selectively degrade some mid and high carbon paraffin hydrocarbons, resulting in the content of long-chain paraffin hydrocarbon being decreased and that of short-chain paraffin hydrocarbon increased, oil viscosity decreases by about 40%, the wax content and resin content decreases, and the rheological property is improved. Physical simulation of oil displacement indicates that oil recovery factor is increased by 6.7%. The pilot test in extra-low permeability oil fields has got desirable result.