A new dispersant ZOC-F44S, which is suitable for oil well cement, was developed by modifying naphthalene dispersant. The dispersant has good compatibility with the film-forming fluid loss additive used in oil fields in China, which eliminates the traditional idea that naphthalene dispersant is not compatible with the fluid loss additive. Compared with ketone aldehyde dispersant, ZOC-F44S dispersant has the advantages of no floating, no dusting, low toxicity and compatibility with various retarders. 

Key words: dispersant, cement slurry, drag reduction, water loss control, temperature resistance

The dispersant of oil well cement is one of the three additives of water loss reducing agent, dispersant and retarder. In the process of cement slurry design, dispersant is always inseparable. Dispersant has the characteristics of making pulping easy, densifying, adsorbing on the surface of cement particles, and thus removing agglomeration of cement particles. Especially when the cement slurry is mixed with high molecular weight polymer, dispersant is often necessary to improve the pulping effect and reduce the consistency of the cement slurry. At present, ketaldehyde condensation compound is the most widely used dispersant in cementing slurry. Because of its good compatibility with film-forming loss reducing agent, it has been widely used. However, there are some defects in the field application of ketaldehyde dispersants: the powder dust causes toxicity, floats easily when water dissolves, and the compatibility problem with retarder in the medium temperature section (60-100℃) is still not solved when adding ketaldehyde dispersants into film-forming loss reducing agent. In view of the above problems, we have developed a new oil well cement dispersant ZOC-F44S by modifying naphthalene dispersant. It has the following characteristics: compatibility with film-forming loss reducing agent (30-120℃) in a wide temperature range; good drag reduction effect; it can reduce the thixotropic structure of film-forming loss reducing agent due to cross-linking, and effectively improve the water loss control; it can expand the types of retarders compatible with membrane-forming loss reducing agent; in addition, it is compatible with high and medium sulfur resistant cement.