Mud Cake Removing to Improve the Well Cementing Quality

This In order to improve the oil well cementing interface strength, the removing agent (JCJ) and cleaning agent (QXJ) were used from the perspective of clearing the mud cake on the borehole wall and wellbore casing. The factors influencing the effect of JCJ and QXJ were researched through metal plate immersion test, cleaning test and cementing strength simulation experiments. The results showed that the removal rate of mud cake could reach to 88% when the metal plate was first soaked in the drilling fluid at 55 degrees C for 40 min when 1% (weight) of JCJ was added into the drilling fluid and then was cleaned in the aqueous solutions within 1% JCJ at 45 degrees C for 25 min. The cementing strength simulation experiments showed that the cementing strengths of the interfaces between the cement and the wellbore casing (the first interface), the cement and the borehole wall (the second interface) could be enhanced to 10.3 and 8 times respectively which indicated the well cementing quality could be improved effectively. Besides, the main properties of drilling fluid did not changed greatly after adding JCJ into the drilling fluid.