Survey Performances of the Polymers in the Water Based Systems Used to Drill Deep Wells

A laboratory study has been undertaken to elucidate the influence of structural parameters of polymer/electrolyte systems commonly used for the formulation of water-based drilling fluids on their performances as filtrate reducers or viscosifiers.High temperatures and salt conditions encountered in the well may modify the rheological properties and this makes the use of polymers necessary. High molecular weight polymers (XC, gums, polyacrylamides), have been used in the formulation of water-based drilling fluids for reducing filtration, facilitating clay stabilisation, improving débris suspension capacity and drillstring lubrication in the drilling operation. The rheological behaviour has been modelised. The modele describe structural changes under shear or at rest as well as the associated stress growth makes it an attractive tool to use in order to improuve hydraulic predictions in deep well drilling.