超微粉体加重高密度油基钻井液的性能

Performance of High-Density Oil-Based Drilling Fluids Improved By Ultrafine Powders

叶 艳 尹 达 张謦文 李 磊 任玲玲

YE Yan YIN Da ZHANG Qingwen LI Lei REN Lingling

为解决高密度油基钻井液中采用常规重晶石粉加重多发生固相沉降的难题，室内分别研究了超微重晶石粉、超微铁矿粉、超微锰矿（中值粒径D50<4 μm）加重高密度油基钻井液性能， 并研究了超微粉体和常规重晶石复配加重高密油基钻井液的性能。 研究结果表明，与普通重晶石加重钻井液相比，采用3种超微加重的油基钻井液的流变性和电稳定性明显增强，超微材料性能优良程度排序依次为超微锰矿粉＞超微铁矿粉＞超微重晶石粉。将超微粉体和普通重晶石复配（质量比1:1）加重至钻井液密度为2.3 g/cm3时，超微锰矿粉、超微铁矿粉和普通重晶石复配加重时可获得良好的流变性，而超微重晶石和普通重晶石复配加重后黏切偏大，流变性差，将乳化剂用量降低50%以上可获得良好流变性，复配加重油基钻井液180℃高温稳定性良好，热滚后的表观黏度仅为68 mPa?s，塑性黏度为59 mPa?s，初终切力为6 Pa/8 Pa，破乳电压达1732 V，稳定性指数TSI仅为0.5。超微粉体加重油基钻井液明显改善了钻井液的流变性、高温稳定性并降低处理剂应用成本，能更好地适应超深井复杂地质条件钻井需要。

In order to solve the problem of the higher solid phase sedimentation of the high-density oil-based drilling fluid used API barite as weighting materials, three kinds of ultrafine powders (particle size≤4 μm),API barite and the complex system of ultrafine powder and API barite in mass ratio of 1:1 was respectively added in the high-density emulsion inversion oil-based drilling fluid and the relative performance was evaluated. The results showed that, compared to the API barite, ultrafine powders could improve greatly the rheology and electric stability of high-density oil-based drilling fluid, micromax did the best effort, and then was microdense, the last was microbarite. When adding the complex sytem of ultrafine powders and API barite in mass ratio of 1:1, only the drilling fluid with density of 2.3 g/cm3 containing micromax and microdense could have a good rheology, while the drilling fluid containing microbarite had worse theology, however, which could be improved by decreasing the dosage of the emulsifier. The apparent viscosity of the drilling fluid, using the complex system of ultrafine barite and API barite in mass ratio of 1:1 as high-density weighting materials, was of only 68 mPa?s, the plastic viscosity was of 59 mPa?s, initial gel strength/10 minute gel strength was of 6 Pa/8 Pa, at the same time, demulsification voltage was greater than 1732 V, and stability index TSI was 0.5. Ultrafine powders technology significantly improved the theology and the static high temperature stability of the drilling fluid and reduced the cost, which could easily meet the needs of ultra-deep well complex geological conditions.