Lab Studies On The Affecting Factors Of The Polymer Drilling Fluids Performance

Most new wells drilled by shallow water oil development company are on artificial islands. Limited by the location, most wells are extended reach wells with maximum deviation angle of70°.The upper well section is deviated and the lower section requires steady deviation and then drop angle. The horizontal shift is about2000m or above. Meanwhile, this wells located on a very sensitive seaside area so that environment protection should be concerned, which means that the requirement of drilling fluids is even higher.This paper mainly studies dispersity drilling fluids and polymer drilling fluids. Studies the lab test between PEG400,PEG2000, PEG10000, PVP and other simple surfactants such as Tween-80, SDBS, CTAB and water soluble polymers such as HP AM and80A51. The results show that PEG, PVP and the simple surfactants can decrease the viscosity of the water soluble polymer solutions. PEG and PVP complexed with polymer through H-band, decrease the solubility of the polymer. The micelles of simple surfactants can complex with polymer through H-band, break the structures inter the polymer, so as to decrease the viscosity of the polymer solutions. Mixed surfactants, such as Tween-80/CTAB=99/1,or SDBD/CTAB=99/1, can also decrease the viscosity of the solutions, the present of CTAB in the micelle increase the interactions between micelles and polymers.The above studies provide the theoretical basis of the application of polymer drilling fluids in the shallow water drilling.