Solidification treatment technology on the wasted polysulfide drilling fluid in Xinjiang Oilfield

At present, it is hard to conduct the harmless treatment on the wasted polysulfide drilling fluid to reach the national standard, especially the noticeably high COD and pH value. In this study, the potassium calcium based polymer mud prepared in lab, with COD as high as 22 466.4 mg/L and pH value at 11.45 originally, was taken as the sample. The drilling fluid was solidified by adding MTH-1, MTH-2, MTH-3, fly ash and cement; and tests were conducted to determine the optimal proportions. The results showed that the optimal recipe was 2.5 wt% MTH-1, 2.5 wt% MTH-2, 8 wt% fly ash and 35 wt% cement while MTH-3 was used to adjust the pH value during the curing period. With the above treatment, COD and pH value of the leachate could meet the "Integrated Wastewater Discharge Standard(GB 8978-1996)". Field test on wasted drilling mud from three wellsites further confirmed the above conclusion.