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分别以CaCl2、HCOOK、HCOONa和NH4Ca(NO3)3为内相,配制具有相同活度(0.9)、相同密度(1.8 g/cm3)的油基钻井液体系,油水体积比为80∶20。比较了4种钻井液的流变性、动态/静态沉降性能、黏弹性、触变性,考察了NH4Ca(NO3)3钻井液的抗污染能力。结果表明,150℃滚动老化16 h后,相同剪切速率下,NH4Ca(NO3)3内相油基钻井液体系剪切应力最小,黏度最低。在50℃、170.3 s-1下,该体系密度降低了0.255 g/cm3,其他3种钻井液的密度降低值⊿ρ为0.513~0.545 g/cm3;相同剪切应力下,NH4Ca(NO3)3钻井液弹性模量和黏性模量的比值(G’/G’’)最大,体系动态沉降稳定性能最好。在10000 r/min下搅拌30 min后在50℃静置16 h,NH4Ca(NO3)3钻井液体系的表面张力为27.744 mN/m2,上层分离油体积为1.37 mL,剩余溶液的上下层密度差为0.038 g/cm3;该体系的凝胶尖峰为3.47 Pa,静态沉降稳定性和触变性最好。NH4Ca(NO3)3钻井液体系抗污染能力较强,可以抗10%劣土污染和15%盐水侵入污染。
The oil-based drilling fluid system with the same activity (0.9) and the same density (1.8 g / cm3) was prepared by using CaCl2, HCOOK, HCOONa and NH4Ca (NO3) 3 as the internal phases respectively and the volume ratio of oil to water was 80:20. The rheological properties, dynamic / static settling properties, viscoelasticity and thixotropy of four drilling fluids were compared. The anti-pollution ability of NH4Ca (NO3) 3 drilling fluid was also investigated. The results show that under the same shear rate, the shear stress of the inner system of NH4Ca (NO3) 3 oil-based drilling fluid is the lowest and the viscosity is the lowest after rolling aging at 150 ℃ for 16 h. Under the same shear stress, the density of NH3Ca (NO3) 3 was reduced by 0.255 g / cm3 at 170 ° C-1 at 50 ° C and 0.513-0.545 g / cm3 for the other three drilling fluids. The ratio of elastic modulus to viscous modulus (G ’/ G’) of drilling fluid is the largest, and the dynamic settling stability of the system is the best. The surface tension of NH4Ca (NO3) 3 drilling fluid was 27.744 mN / m2 and the volume of the upper separation oil was 1.37 mL after stirring at 10000 r / min for 30 min and then standing at 50 ℃ for 16 h. The density of the upper and lower layers of the remaining solution 0.038 g / cm3. The gel peak of this system is 3.47 Pa, and the static sedimentation stability and thixotropy are the best. NH4Ca (NO3) 3 drilling fluid system has strong anti-pollution ability, resistant to 10% inferior soil contamination and 15% saline intrusion.