Oil well cement anti-pollution agent

The invention discloses an oil well cement anti-pollution agent. The anti-pollution agent is prepared from hydroxide A and silicate B in the weight ratio being (40-60):(60-40), wherein the hydroxide Ais at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide; the silicate B is at least one of sodium silicate, potassium silicate, aluminum silicate and calcium silicate. The anti-pollution agent is applicable to well drilling and cementing processes of petroleum and natural gas, has a function of preventing pollution to cement paste and drilling fluids and can phenomena of bubbling, core covering and pre-thickening of the cement paste and the drilling fluids, increase fluidity of cement paste and improve the strength of set cement. 本发明公开了种油井水泥抗污染剂，其由重量比为(40～60):(60～40)的氢氧化物A和硅酸盐B构成，其中，氢氧化物A为氢氧化钠、氢氧化钾、氢氧化钙、氢氧化镁中至少种，硅酸盐B为硅酸钠、硅酸钾、硅酸铝、硅酸钙中至少种；该抗污染剂适用于石油、天然气钻井固井过程中，具有防止水泥浆与钻井液的污染的作用，可以防止水泥浆与钻井液发生"鼓包"、"包芯"和提前稠化的现象发生，同时可以增加水泥浆流动度，提高水泥石的强度的效果。