陕北低渗透油田采出水与清水回注可行性研究

Compatibility study of formation and clean water mixed injection in North Shaanxi permeable oil fields

清污混注技术目前已经成为油田注水开发工艺的重要手段,也是合理利用资源的有效途径,但是会引起结垢方面的一些问题。为了防止清污混注的结垢问题可能对地层、管线和设备造成的伤害,需要对清水和地层水(长7)进行配伍性实验研究。实验采用静态模拟法来研究混合水的配伍性,通过对水质离子含量分析、结垢量、失SO2-4量、失Ca2+量和垢型的分析,对清水和地层水(长7)的混合性质进行研究。结果表明:采出水(长7)与清水混合后形成的主要结垢类型为硫酸钡和硫酸锶。清水与地层水(长7)的混合体积比为2∶8时,混合水的失SO2-4量与结垢量达到最高,分别为127.4 mg/L和290.5 mg/L,达到地面结垢最大化,可以一次性除去成垢离子。絮凝处理后的混合水与地层水(长7)的混合体积比为7∶3时,混合水的失SO2-4量与结垢量达到最低,分别为1.89 mg/L和1.00 mg/L,与地层水配伍性良好,可以进行回注。

Sewage and clean water mixed injection（ SCWMI） is becoming an important means of oilfield water injection development technology as well as effective way to reasonable use of resources,but it can cause some scaling problems. In order to decrease the damage of scaling to assise,pipeline and equipment,the experimental research on the compatibility of fresh water and formation water（ from Chang-7 layer） was conducted based on the simulation method. By analyzing the ion content,amount of scale,SO4^2- and Ca^2＋ loss content and scale type,respectively,the mixed property of fresh water and formation water was investigated. The result indicates that the main scale types of mixed water are barium sulphate and strontium sulphate. When the volume ratio of fresh water to formation water is 2 ∶ 8,the highest sulfate loss content（ 127. 4 mg / L） and amount of scale（ 290. 5 mg / L） are achieved,which means the amount of scale of mixed water can be maximized on ground,and the scale ions in mixed water can be removed before injecting into layer. When the processed mixed water is remixed with formation water at volume ratio of 7 ∶ 3,the lowest sulfate loss content（ 1. 89 mg / L） and amount of scale（ 1. 00 mg / L） are obtained,which are compatible with formation water and can be used as injected water.