稠油采出水制备纳米颗粒及其泡沫驱油研究

针对油田采出液难处理、纳米颗粒制备成本高的问题,采用鲁克沁稠油采出液合成菱-球混合形纳米碳酸钙颗粒,通过泡沫稳定性实验及岩心驱替实验,研究纳米碳酸钙颗粒的稳泡性能及该泡沫体系的驱油效果。结果表明:合成的纳米碳酸钙颗粒可有效增强泡沫稳定性;当纳米颗粒质量分数为0.2%、体系矿化度为5 000 mg/L、温度为80 ℃时,纳米颗粒发泡体积为530 mL,析液半衰期达528 s;泡沫体系具有良好的耐盐、耐温及抗吸附性能;水驱油藏(含水率为达80%)转泡沫驱,纳米颗粒泡沫可形成3 MPa左右的稳定驱替压差,采出率由39.84%增至80.16%。利用油田采出液稳定合成出纳米碳酸钙颗粒,可作为泡沫稳定剂提高泡沫稳定性,并用于矿场驱替试验改善泡沫驱油效果。

Study on Preparation of Nanoparticles from Produced Water of Heavy Oil and Its Foam Flooding

On account of intractable treatment of produced fluid in oilfield and high cost of nanoparticle preparation, rhombic-spherical mixed calcium carbonate nanoparticles were synthesized from produced fluid of Lukeqin heavy oil. Foam stability test and core displacement test were conducted to study the foam stabilization performance of calcium carbonate nanoparticles and the oil displacement effect of the foam system. The results showed that the synthesized calcium carbonate nanoparticles effectively enhanced the foam stability; when the mass fraction of nanoparticles was 0.2%, the salinity of the system was 5 000 mg/L and the temperature was 80 ℃, the foaming volume of nanoparticles was 530 mL, and the foam drainage half-life was 528 s; the foam system had excellent salt and temperature tolerance and adsorption resistance; the water flooding in the reservoirs (water content up to 80%) was converted to foam flooding, and the nanoparticle foam had a stable flooding pressure difference of about 3 MPa, and the recovery rate was increased from 39.84% to 80.16%. Calcium carbonate nanoparticles were stably synthesized by using oilfield produced fluid, which can be used as foam stabilizer to improve foam stability, and can be used in field flooding test to improve foam flooding effect.