油田注入系统滋生物对聚驱渗流特性影响研究

Impact of breed in oilfield injection system on seepage characteristics of polymer flooding

关键词:  大庆杏树岗油田  聚合物溶液  配注入系统  胶状物  聚驱效果  物理模拟 

Key words:  Daqing Xingshugang Oilfield  polymer solution  injection distribution system  jelly  polymer flooding effect  physical simulation

摘要:

聚合物驱注入系统中过滤器和管线内壁存在的黏性胶状物是注入水中微生物在系统内大量繁殖的代谢物,它会随聚合物溶液进入储层,对聚合物驱开发效果造成影响。采集了杏树岗油田聚合物配注系统内滋生胶状物,与聚合物溶液混合形成含胶状物聚合物溶液,开展了胶状物对聚合物驱开发效果影响的实验研究。结果 表明,与聚合物溶液相比较,胶状物在多孔介质内传输运移能力较差。当储层岩心渗透率较低(Kg<1 000×10-3 μm²)时,聚合物溶液中胶状物主要滞留在岩心端面附近区域。胶状物会对聚合物驱增油效果造成不利影响,但随储层渗透率级差增加,其影响程度逐渐减小。并联模型实验表明,水驱过程中分流率呈现“高渗透层增加,低渗透层减小”趋势,注聚初期和中期分流率呈现“高渗透层减小、低渗透层增加”趋势,后期分流率呈现相反趋势,即出现“剖面反转”现象。岩心实验表明,当采用不同注入方式(恒速和恒压)注入相同(类型和段塞尺寸)聚合物溶液时,聚驱采收率会存在差异。现场聚驱注入方式通常是“恒速”或“恒速”到“恒压”方式。因此,在岩心实验时,聚合物溶液注入方式的选择必须考虑现场储层破裂压力的影响,否则,现场按照室内推荐方案执行就会遇到注入井注入困难问题。 

Abstract:

The viscous jelly, which exists in the filter and pipe wall of polymer injection system, is the metabolite of microbial populations within the injection water system,and it will affect the development effect of polymer flooding after entering the reservoir pore. To meet the demand of field technical decision, the spawned jelly of polymer injection allocation system in Xingshugang oil field was collected, mixed with polymer solution then formed the jelly containing polymer solution, and carried out the research of jelly impact on polymer flooding development effect. The result shows that compared with the polymer solution, the transmission and migration ability of jelly was poor in porous medium. The jelly in the polymer solution mainly stranded near the end area of core when the reservoir core permeability is low(Kg<1 000×10-3 m²). Jelly caused adverse effects on the enhancing oil productivity of polymer flooding, but with the increase of reservoir permeability differential, the degree of influence gradually reduce. Parallel model experiments show that diversion rate appear the trend of “high permeable zone increase, low permeable formation decrease” in process of water drive,the trend of “high permeable zone decrease, low permeable zone increase” in the early and mid polymer injection, the trend in the late is opposite, named “profile inversion”. Core experiment shows that when using different injection ways(constant speed or constant pressure) to inject the same polymer solution(type and slug size), polymer flooding recovery are differently. Polymer injection pattern in field usually is “constant speed” or “constant speed to constant pressure”. Therefore, the choice of polymer solution injection pattern in core experiment must consider the effect of mining reservoir fracture pressure. Otherwise, in accordance with indoor recommendation, the problem of injection difficulty in the injection well will occur.