Title screen

Deep wells suffer from the instability and disintegration of natural polymers and other commonly used additives under high pressure and high temperature condition. As a result, serious problems such as hydraulic loss, stuck pipe, and high torque and drag are expected to take place which leads to a dramatic increase in cost and time. This study presents the functionality of a novel synthetic based acrylamide-styrene copolymer (SBASC) as a supersede additive for water-based drilling mud. First, the SBASC was synthesized using an emulsion polymerization process and its particle morphological and polymer chain structural properties were determined by Field Emission Scanning Electron Microscopy (FESEM) and Fourier- Transform Infrared Spectroscopy (FTIR), respectively. Then, the designated copolymer was added into a mud formulation which is applicable in oil and gas fields, and its performance in the mud was investigated with respect to filtration properties and rheological characteristics. In addition, the rheological characteristics and filtration behavior of drilling fluids containing SBASC were compared with those of a field applicable fluid that contained 9 g of HT starch which is a commercial natural polymer commonly used in drilling fluid industry.

Furthermore, the thermal stability of SBASC was determined by conducting hot rolling and high pressure-high temperature (HP-HT) filtration tests. The obtained results confirmed that the addition of the copolymer enhances the rheological characteristics of the drilling fluid before and after aging at 121.1 °C. Moreover, the filtration behavior at both conditions was improved by introducing SBASC into the fluid, while the best performance was observed for the fluid containing 3 g of SBASC which shows 38.8% and 47.5% fluid loss reduction for HP-HT and LP-LT conditions, respectively. Furthermore, the solubility of SBASC in saline and fresh water is verified by demonstrating a promising solubility in high salinity water sample with different concentrations of a monovalent salt.