某区块致密气采出水水质对回注储层的影响研究

Research on the influence of tight gas produced water quality on reinjection reservoir in a block

为研究致密气采出水回注的可行性,以鄂尔多斯东缘盆地某致密气区块采出水及石盒子组盒8段储层为研究对象,通过水质配伍、黏土膨胀岩心伤害及储层敏感性实验,综合分析采出水水质对回注储层的影响。结果表明:初期采出水经处理后,混合结垢量最大为54 mg/L,配伍性良好;水样无论是单独回注还是混合回注,其黏土膨胀率最大为21.78%,均不会引起黏土膨胀。采出水中悬浮物和含油质量浓度分别限制在10 mg/L和6 mg/L以下,对储层的伤害率低于20%;致密砂岩储层敏感性对回注水主要表现为中等偏弱速敏、弱酸敏。

In order to study the feasibility of the reinjection of the produced water of tight gas,the produced water of a tight gas block in the eastern margin of Ordos and the 8th reinjection layer of Shihezi Formation were taken as the research objects,through water quality compatibility,clay expansion,core damage and reservoir sensitivity experime-nts to comprehensively analyze the impact of produced water quality on reinjection reservoirs.The results showed that the maximum scale of after mixing of the initial produced water after treatment was 54 mg/L,and the compatibility was good.Whether the initial produced water after treatment were re-injected separately or mixed,the maximum clay swe-lling rate was 21.78%,which would not cause clay swelling.Suspended solids and oil content in produced water were controlled below 10 mg/L and 6 mg/L respectively,and the damage rate to the reservoir was less than 20%.The sensi-tivity of reservoir to reinjection water was mainly shown as medium to weak velocity sensitivity and weak acid sensi-tivity.