Study and Application of a New Poly Carboxylic Acids Drag Reducer

Cement slurry mixed in Iraq has strong thixotropy and poor pumpability in summer, and the drag reducers presently in use are unable to render the cement slurries good dispersibility. These problems have seriously affected the safe performance of well cementing. To address these problems, a new poly carboxylic acids drag reducer, BH-D301L, has been developed with monomers such as polyethylene glycol diacrylate, methacrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and aromatic sulphonic acid etc. Using orthogonal experiment, the optimum conditions for the reaction was determined to be as follows:molar ratio of the monomers of 1:4:1:1, reaction temperature of 80℃, reaction time of 2 h, and initiator concentration of 0.4%. The reaction product was characterized by IR spectroscopy and gel permeation chromatography, and was tested for its general performance in different cement slurries in accordance with API RP 10B. Experimental results showed that by adding 0.5% and 1.0% of the drag reducer into a cement slurry formulated with fresh water and a cement slurry formulated with saturated saltwater, the rheology of the cement slurries were obviously improved. The compressive strengths and thickening time of the cement slurries satisfied the requirements of industrial standards. At simulated temperatures of 45-65℃, a high-density salt-containing cement slurry treated with 1.0% drag reducer had flow index of greater than 0.7 and consistency factor of less than 0.58 Pa·sn. The thixotropy of the cement slurry treated with the new drag reducer had thixotropy increased less obviously. Gel strength of the cement slurry was less than 3 Pa and 24 h compressive strength exceeded 14 MPa. The cement slurry treated with the drag reducer had thickening property and settling stability all satisfied the needs of well cementing job, and was successfully used in field operations.