The Rheological Impact of Polymers and Salt on Xanthan Gum in Drilling Fluids

Abstract

Drilling fluids serve a vital role during drilling operations. They are divided into water based muds (WBM) and oil based muds, the choice between them depends on specific project needs. Xanthan gum is a highly popular WBM additive due to its high viscosity at low concentrations. It also has a good salt tolerance and exhibits the desirable pseudoplastic behavior of a drilling fluid. This thesis presents a study that investigates how xanthan gum is affected by polymers and salts. Using an aqueous xanthan gum base, 16 samples were prepared. By adding various combinations of polymers and salts, the rheology of the fluids was tested. Shear stress measurements using a viscometer are conducted. Hot rolling to simulate mechanical and thermal wear is done. The linear viscoelastic region of selected samples is analyzed using a rheometer. Additionally, measurements using zeta potential apparatus are performed. The results show that salts improve the fluids stability and decreases the yield stress. However, CaCl2 seemed to have a degradable effect on the fluid when using a cellulose based polymer. The study finds indications that starch based polymers bond better with xanthan gum compared to cellulose based polymers.

Drilling fluids serve a vital role during drilling operations. They are divided into water based muds (WBM) and oil based muds, the choice between them depends on specific project needs. Xanthan gum is a highly popular WBM additive due to its high viscosity at low concentrations. It also has a good salt tolerance and exhibits the desirable pseudoplastic behavior of a drilling fluid. This thesis presents a study that investigates how xanthan gum is affected by polymers and salts. Using an aqueous xanthan gum base, 16 samples were prepared. By adding various combinations of polymers and salts, the rheology of the fluids was tested. Shear stress measurements using a viscometer are conducted. Hot rolling to simulate mechanical and thermal wear is done. The linear viscoelastic region of selected samples is analyzed using a rheometer. Additionally, measurements using zeta potential apparatus are performed. The results show that salts improve the fluids stability and decreases the yield stress. However, CaCl2 seemed to have a degradable effect on the fluid when using a cellulose based polymer. The study finds indications that starch based polymers bond better with xanthan gum compared to cellulose based polymers.