Synthesis and Characterization of Salt Tolerant Ternary Polyampholyte as Rheology Enhancer and Fluid Loss Additive for Water-Based Drilling Fluids

Nurbatyr  Mukhametgazy1,2,Email

Iskander Sh.Gussenov1,2

Alexey V.Shakhvorostov1

Heikki Tenhu3

Munziya Abutalip4

Sarkyt E.Kudaibergenov2,Email

1Institute of Polymer Materials and Technology, Almaty 050019, Kazakhstan.
2Department of Chemical and Biochemical Engineering, Satbayev University, Almaty 050013, Kazakhstan.
3Department of Chemistry, University of Helsinki, Helsinki, Finland.
4Lab of Renewable Energy, National Laboratory Astana, Nazarbayev University, Astana, 010000, Kazakhstan.

Abstract

A novel ternary polyampholyte (TPA) was synthesized via free radical copolymerization in deionized water using ammonium persulfate as an initiator. The TPA composition included 80 mol.% acrylamide (AAm), 10 mol.% 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS), and 10 mol.% (3-acrylamidopropyl) trime-thylammonium chloride (APTAC). TPA was used as an alternative to low viscosity polyanionic cellulose (PAC-LV) to prepare bentonite based drilling fluids with different concentrations of NaCl (1-35 wt.%). Gel strength (GS) measurements demonstrated that, at a 6:1 [initiator]:[catalyst] ratio, even in high salinity brines (25-35 wt.%), the GS values exceeded industry standards, highlighting the superior performance of ben-tonite/ternary polyampholyte (BT/TPA) in high salinity media. Notably, TPA addition significantly reduced the filter cake thickness to 0.09 cm, outperforming BT/PAC-LV (0.18 cm) and bentonite alone (0.41 cm). Furthermore, the BT/TPA drilling fluid exhibited the lowest permeability/thickness ratio at 13 mD/cm, indicating its potential as a rheology enhancer and fluid loss additive for salt-resistant Water-Based Drilling Fluids (WBDF) applications. The filtration performance of bentonite and bentonite/polymer dispersions showed a clear trend in fluid loss values: BT/TPA < BT/PAC-LV < Base flu-id. The high-salinity BT/TPA drilling fluid had remarkably low fluid loss, measuring just 3.5 ml, well below the API standard limit of 12 ml.

Synthesis and Characterization of Salt Tolerant Ternary Polyampholyte as Rheology Enhancer and Fluid Loss Additive for Water-Based Drilling Fluids