提高第二界面固井质量的钻井液与前置液研究

Study on drilling fluid and preflush for improving cementing quality of the second contact surface

针对提高第二界面固井质量的问题,研究出了多功能钻井液和SF-1冲洗前置液。对这两种体系的性能评价表明:加入矿渣后多功能钻井液的滤失量大大降低,泥饼的胶结强度提高,从而降低了钻井液对地层的损害;加有活性组分的SF-1前置液具有较强的稀释钻井液、降低粘度和切力的作用,提高了钻井液和水泥浆的相容性。现场应用表明,多功能钻井液须与MTC固井液配合使用,才具有提高第二界面固井质量的效果;SF-1前置液改善了水泥环与套管和水泥环与井壁的胶结环境,增强胶结力,提高了水泥浆的顶替效率,有效地提高了固井质量。密度介于钻井液与水泥浆之间的加重前置液在现场使用效果良好,固井质量优质,钻井液与水泥浆界面清晰。

Aiming at improving the cementing quality of the second contact surface, multifunction drilling fluid and SF-1 preflush have been developed and evaluated. For adding blast furnace slag (BFS) into the multifunction drilling fluid, filter loss of the fluid can be reduced, cementing strength of the mud cake can be enhanced and the formation damage by the fluid can be prevented. Since SF-1 preflush has the abilities of thinning, visbreaking and reducing shear rate, compatibility of drilling fluid with cement slurry can be improved. The drilling fluid and preflush have been used in the field and the results showed that the multifunction drilling fluid must be used with MTC cementing fluid to improve the cementing quality of the second contact surface. SF-1 preflush could improver the cementing state of the contact surfaces, increase the cementing strength and cement slurry displacing effect. The preflush with density between drilling fluid and cement slurry has been used in field and excellent cementing quality has been obtained.