特低渗透油田注水地层结垢矿物特征及其影响

Scale Compositions of Water Injection Formations in Ultra-Low Permeability Reservoir and it's Effect

通过注入水和地层水的配伍实验、检查井岩心矿物鉴定、孔隙度与渗透率恢复实验,研究了安塞特低渗透油田注水地层结垢对地层孔隙度和渗透率的影响。结果表明,注入水为Na2SO4型,地层水为CaCl2型且含Ba2+,由于注入水和地层水不配伍,储层长期注水后形成了较为丰富的结垢矿物即方解石、重晶石。结垢矿物的生成量与孔隙度、渗透率的下降幅度具有很好的相关性。注水开发20年后,孔隙度平均下降幅度为15%,渗透率平均下降幅度为31.73%,就储层伤害而言,碳酸钙垢大于硫酸钡垢。

Based on the compatibility test of injected water with formation water,the core mineral composition identify of inspection wells,the recovery test of the formation porosity and permeability,the influences of the scale formation after water injection in Ansai low permeability oilfield on the formation porosity and permeability were studied.Because the injected water,belonging to Na2SO4 type,have poor compatibility with formation water,belonging to CaCl2 type and containing Ba^2＋,calcite and Barite scales were produced in the water-flooded reservoirs.The scale content had a favorite relativity with the damage range of porosity and permeability,and the average damage level of porosity and permeability were 15% and 31.73%,respectively.Calcium carbonate damaged to the reservoir formations more seriously than barium sulfate did.