南海西部油田井下除防垢工艺探索与实践

Exploration and practice of underground scale removal in oilfields of western South China Sea

南海西部油田油井结垢给生产、修井及测试作业带来较大不利影响,先后采取了井下定期挤注加药、超声波及机械刮管除防垢措施,但效果均不理想。为解决结垢难题,开展了化学螯合+挤注缓释地层除防垢、井下管柱及机组水力冲洗/磨铣除垢,以及贵金属、涂层等综合除防垢工艺研究。同时,实验优选了性能优良的除垢剂,98℃下硫酸钡垢除垢率可达65%;优选出的防垢剂最低有效质量浓度为5 mg/L,当驱替800 PV后,其质量浓度仍为MIC值(最低有效质量浓度),可满足长期有效的防垢要求,具有较好的现场应用价值。目前,已实施4口井的化学除防垢作业,均取得了较好的措施效果,其中W9井稳产增油效果最显著,措施作业后连续稳产16个月,挽回原油损失2.2×10~4m^3。

Oil well scaling has a great adverse eftect on production, well repair and test in the oilfields of western South China Sea, measures such as downhole regular injection and dosing, uhrasonic scaling and mechanical scaling are adopted, but the effect is not ideal. In order to solve the problem of scaling, research of chemical chelating and descaling and anti-scaling by squeezing slow- release of layer were carried out, research of hydraulic rinsing/milling descaling of tubing and ESP underground were carried out, and research of comprehensive removal and anti-scaling technology of precious metals and coatings were carried out. At the same time, the excellent detergent was selected through the experiment, of which scale dissolving rate of barium sulfate can reach 65% under 98℃. The minimum effective concentration of the optimized anti-scale agent was 5 mg/L. After displacement of 800 PV, the mass concentration is still MIC, which can meet the requirement of long term effective scale prevention. And it has good value of field application. The chemical de-scaling and anti-scaling of four wells in the oilfields of western South China Sea has been carried out, which has achieved good resuhs at present. The effect of W9 was the most remarkable, the continuity- production time was 16 months after the measure, which retrieved crude oil of 2.2×10^4m^3.