Experimental Investigations Into the Performance of a Flat-Rheology Water-Based Drilling Fluid

The aqueous drilling fluid (AF) with unique flat rheology (FR), as a potential alternative to nonaqueous fluids (NAFs), is meaningful in deepwater operations. In this work, a novel FR water-based mud (WBM) was presented. An evaluation of FR profiles was conducted on the designed system by detecting the typical rheological data at a certain temperature and pressure range. The results showed that for the newly developed WBM, in addition to typical FR parameters [i. e., 6- and 3-rev/min readings and yield points (YPs)], the viscosity term also delivers near-constant variations in the temperature range of 39 to 150 degrees F. To attain FR profiles, the rheological modifier appears to be necessary for its temperature-activated behavior. In addition, the FR WBM displays lower pressure and temperature dependence. The laboratory contamination tests indicated that the WBM system possesses excellent inhibition and lubricity properties as well as a strong tolerance to the contamination of seawater and sand/mudstone cuttings.