甲酸盐溶液对饱和盐水磺化钻井液的适应性评价

Adaptability evaluation of formate solution to saturated brine sulfonated drilling fluids

关键词:  饱和盐水磺化钻井液  甲酸盐基液  重晶石  抗盐钙污染 

Key words:  saturated brine sulfonated drilling fluids  formate base fluid  barite  tolerance to salt and calcium

摘要:

超深井多选用高密度饱和盐水磺化钻井液体系,本研究引入高浓度甲酸钾溶液作为钻井液基液,有效减少高密度钻井液固相含量,提高钻井液及关键处理剂的热稳定性,同时加快超深井深部巨厚盐岩层钻井速度、减缓钻具腐蚀,充分发挥甲酸盐钻井液良好的抑制性和泥饼质量,低环空压耗等优势。讨论了重晶石在甲酸钾溶液中的溶解性以及甲酸钾溶液的抗盐抗钙污染能力,研究结果表明,重晶石在甲酸钾溶液中几乎不溶,所以在饱和盐水磺化钻井液中可用30%～70%(w)甲酸盐溶液提高基液密度,然后采用重晶石进行加重是可行的。此外,氯化钠和石膏在甲酸盐溶液中的溶解度均有不同程度的降低,可用于进一步提高磺化钻井液的抗盐抗钙污染能力。

Abstract:

Potassium-based solution with high concentrations is brought into saturated brine sulfonated drilling fluid in the complex ultra-deep wells, which can reduce the solid content of high-density drilling fluid, improve the thermal stability of the drilling fluid, temperature resistance of key treatment agents and the drilling speed in the extremely thick ultra-deep salt formation, and slow down the drilling corrosion. At the same time, formate drilling fluids have the advantages of inhibitive ability, good quality of mud cake, low annular pressure lost and friction coefficient. This article discussed the solubility of barite in potassium formate solution and its tolerance to salt and calcium. The experimental results showed that barite was almost insoluble in potassium solution so that the formate solution of 30%～70% was used to improve the density of base fluid and then choosing barite to aggravate it was feasible. In addition, the solubility of sodium chloride and gypsum in formate solution both reduced by different degrees, which could be used to further increase the tolerance to salt and calcium of sulfonated drilling fluid.