超高密度水基钻井液加重剂研究

超高密度水基钻井液常规加重剂易引起黏度效应，导致钻井液黏度过大失去流动性。采用表面活化和粒度级配的方式对重晶石进行了优化。通过电势影响和流变性实验确定出表面活化剂（RAB）的最佳加量，并在此基础上，以经典堆积理论为基础，采用Dinger-Funk分布方程计算出不同分布模数下的粒度范围，通过大量室内实验，确定出最佳粒度级配。通过优化生产工艺生产出工业级的特殊重晶石，在四川地区多口高压深井气井进行了应用，成功配制出超高密度水基钻井液（密度≥2.65 g/cm3）。现场应用结果表明，以特殊重晶石加重的超高密度水基钻井液，具有加重密度高、流变性可控、抗盐水侵等特点，满足实际施工需要，具有较高的推广价值。

Study on weighting agent of ultra-high density water-based drilling fluid

The conventional weighting admixture of ultra-high density water-based drilling fluid may lead to viscosity effects,which means that the drilling fluid could lose its flow property due to high viscosity.In this paper the properties of barite optimized by using surface activation and particle classification.First the optimum dosage of surfactant(RAB) was determined after experiments of electric potential effect and rhelogy behavior;furthermore,on the basis of classical accumulation theory and plenty of laboratory experiments,the particle size ranges under different modulus and the optimum particle classification were calculated by using the distribution equation of Dinger-Funk.An industrial specific barite was produced by adjusting and optimizing production process and then was applied into several deep wells with ultra-high pressure in Sichuan area.Finally,the ultra-high density water based drilling fluid(with the density of greater than or equal to 2.65 g/cm3) is successfully prepared on site.The applied results show that the ultra-high density water-based drilling fluid with special barite has characteristics of weighted high density,easy controlled rhelogy behavior,and anti-salt & water invasion resistant.It can satisfy the actual requirement of practical drilling operation,and thus worth popularizing.