Study On Salt Shade Control Technology In Oilfield Of Bohai Oilfield

Wax deposition problems were observed in three high waxy oil wells of WHPA platform of one oilfield in Bohai, which influenced the production of wells. The problems existed still after they were injected wax inhibitors. To relief wax deposition, experiment devices were designed, and the main reasons of wax deposition were tried to find and wax control methods were presented in this thesis.The analysis on waxy oil properties showed that crude oil in A3, A7 and A10 wells were high wax content oil with high wax appearance point (WAP) that exceed to 20℃. The gas chromatography showed that the high carbon numbers of A3 wax sample was less than that of A7 and A10, and the relative contents for paraffin of A3 was more than that of A7 and A10. When the temperature was below the WAP, the wax deposition quantities of A3 would be more than that of A7 and A10. The wax melting point test showed that the temperature of heat fluids for washing wells should be more than 85℃.After 1-type cold finger was revised to U-type one, the wax on surface was more uniform. Wax deposition rate got through experiments can reflect the features of waxy oil in WHPA platform. The experiments showed that the rates of A3 and A10 were 115.2 g/m2-h, while that of A7 was 230.3g/m2-h.Wax deposition experiments showed that wax deposition was a dynamic process from macro view, and wax deposition rates were different during different periods. The total trend was that the rate increased with time and would become more flat. But after increasing in the first day, remarkable decreasing in the second day, then it would continue to increase. The color of deposit became darker and darker.Wax deposition process can be observed through microscopic image analysis system, and wax deposition peak temperature range can be obtained. The tests showed that the wax crystal appearance point and peak temperature range of A3, A7 and A10 were 36℃and 12-18℃,34℃and 14～2℃, and 38℃and 12～20℃.After wax control technologies were analyzed, wax control schemes were:combined application of. vacuum-insulated tubing (VIT) and wax inhibitor, or VIT for A10 well, VIT and light crude oil injected for A3 and A7. Simulation calculation showed that the wellhead temperature can be increased through VIT. The recommended wax removal scheme were paraffin remover injection, hot washing with paraffin remover or mechanical removing paraffin.The wax inhibitor OGW-1 and LOGW-3 were recommended by experiments, and the effects of which were better than BHFL-01 used before. And then paraffin remover was proposed, that is, YFJNC-05, YFJNC-04, BHFL-01 or OGW-1 for short time deposits, and YFJNC-05, YFJNC-04 or BHFL-01 for long time deposits.