Effect Of Barite Hydrophilicity Modification And Its Effect On Drilling Fluid

With increasing depth of the oil well, a high-density oil-based drilling fluid would be need in case of some special oil.API barite’s average diameter is relatively large and surface is lipophilic.So the barite in the oil based drilling fluid are easily escaped from each other and then precipitated by gravity. The barite precipitated in the bottom of increased difficulty of drilling and seriously affected the drilling progress and increased drilling costs. A method for solving the problem that barite is settling in the oil is make a lipophilic modification on the surface of barite to get lipophilic barite to make it still disperse well in the oli for a long time and reduce rate of settlement. The method of Preparation of lipophilic is simple and low cost and it also has good results.So the lipophilic barite has a huge potential for development in the future.This article uses Superfine barite as modified objects and choses three common methods: coupling agent method, cationic surfactant method and alumina hydrate-anionic surfactant compound-covered method.Coupling agent method:Selecting the silane coupling agent KH550and titanate coupling CT-201as modifying agent.The experimental result shows that the modification effect of silane coupling agent is better than the modification effect of titanate coupling CT-201. When the amount of modifying agent is5%by weight of barite the activation index of lipophilic barite is0.5.But modifying agent adsorbed on the surface of barite is unstable. After Soxhlct extraction,modified barite turned to be little lipophilicity.Cationic surfactant method: Selecting cationic surfactant DTAB as modifying agent.Experimental result shows that the activation index of lipophilic barite reached0.92and dispersibility of lipophilic barite in diesel system is greatly improved. alumina hydrate-anionic surfactant compound-covered method:Experimental test shows that activation index of lipophilic barite reached0.98M. Dispersibility of lipophilic barite in diesel system is better than others. This article chooses the third method to modify barite.After choosing emulsifiers,organic clay and filtrate reducer by experiment and using lipophilic barite as weighting agent finally article get a oil based drilling fluid formulation(anti-high-temperature is220℃and density is2.4g/cm). The oil-based drilling fluid formulation:diesel+20%CaCl brine+3%EMUL-1+0.5%ABS+3%organic clay(Zhejiang Tianlong)+3%filtrate reducer Oxidized asphalt(softening point is180℃)+lipophilic barite.This oil-based drilling fluid has good performance in anti-pollution and anti-water-intrusion.Using lipophilic barite as weighting agent in saturated brine water-based drilling fluid system(anti-high-temperature are180℃and220℃,density is2.4g/cm3). Contrastion test shows that the effect of lipophilic barite is worse than the effect of API barite in water-based drilling fluid system.Lipophilic barite is not available for water-based drilling fluid system currently.