柯探1井高钙盐水层的钻井液技术

柯探1井是部署在新疆阿克苏地区柯坪县的一口风险探井,在寒武系沙依力克组钻遇高钙盐水层,持续不断地钙侵导致重晶石沉降,发生了卡钻等一系列井下故障。为优化复杂地质条件下钻井液配方,现场开展多种试验,提出了钙盐水层钻井液等一系列钻井液配方:①三开配浆即用海泡石代替现在的膨润土,控制好低密度固相,为转换四开饱和盐水钻井液做好准备;②除聚合物之外,常见的淀粉比较适合该区块;③除应用纯碱和小苏打除钙外,使用一些硅酸钾,能预防钙侵,生成的硅酸钙对井壁稳定、防塌有一定的帮助,同时钾离子可以提高钻井液的抑制性;④采用质量较好的白沥青,实现快速优质钻进。现场应用表明,四开高钙盐水层,电测无阻卡,井径规则,套管一次性下到位,钻井液性能满足固井施工要求,现场施工效果良好。

Drilling fluid technology for high calcium brine layer in Ketan-1 well

Ketan-1 well is a risk exploration well deployed in Keping County of Aksu area in Xinjiang. During drilling in Shayilik formation of Cambrian system, high calcium brine layer was encountered, and barite settlement was caused by continuous calcium invasion, and a series of downhole failures such as pipe sticking occurred. In order to optimize the drilling fluid formula under complex geological conditions, a variety of field tests were carried out for a series of drilling fluid formulations. ① In the third spud, sepiolite is used to replace the present bentonite to control the low density solid phase and prepare for the conversion of the fourth spud saturated salt water drilling fluid; ② Besides polymer, common starch is more suitable for this block; ③ In addition to the application of soda ash and sodium bicarbonate to remove calcium, some potassium silicate can be used to prevent calcium invasion. The generated calcium silicate is helpful to wellbore stability and collapse prevention, and potassium ion can improve the inhibition of drilling fluid; ④ High quality white asphalt is used to realize fast and high quality drilling. The field application shows that the high calcium brine layer has been opened four times in Ketan-1 well, the well diameter is regular, the casing is put in place at one time, the drilling fluid performance meets the requirements of cementing operation, and the field operation effect is good.