Research Of Improving The Cement Quality Of The Second Interface By Mud Cake Solidification

The main factor in the quality problem of cementing interface is the formation of a noncurable mud cake layer on the borehole wall.At present,the treatment of mud cake mainly includes mechanical removal and chemical washing,but there are still some problems in the cementing quality after mud cake removal.In recent years,based on the idea of MTC cementing technology,a new technology has provided a method to solve the cementing interface problem by adding active components to the drilling fluid to form a certain strength of mud cake with subsequent activation in order to achieve an overall solidification of the cementing interface.Based on the research and summarization of the experimental methods and ideas of the current mud cake curing technology,this paper puts forward the use of metakaolin and ultrafine slag as the cake curing material,with sodium silicate and sodium hydroxide as activators to achieve the mud cake solidification.Based on the test method for compressive strength of cement stone,the performance of potential active material on curing bentonite were studied;the change of drilling fluid loss properties and rheological properties after the addition of the cake curing material is tested;a new characterization method of mud cake curing strength is put forward and the strength of solidified mud cake is tested by self-made mud cake strength test device;the concept of mud cake breaking pressure is put forward as an evaluation index of mud cake curing technology performance and the shear strength,hydraulic cementation strength,anti-erosion and anti-impact performance of mud cake are tested.The results of this paper show that the metakaolin and ultrafine slag have good curing ability to the bentonite,and the strength of mud cake formed by the drilling fluid with mud cake curing material is improved obviously after the activation of the activator.The addition of the cake curing material has little effect on the water loss and rheological properties of the drilling fluid.Finally,the effect evaluation experiment results show that after using the mud cake curing technology proposed in this paper,the shear strength,hydraulic cementing strength and mud cake breakthrough pressure of the cementing interface is improved obviously and the solidified mud cake has a good stability.