Investigating the effects of nano-Fe3O4 and MWCNTs on the filtration and rheological properties of water-based muds at elevated temperature and pressure

Thermal degradation of water-based muds is a common occurrence while drilling wells in elevated to high temperature and pressure formations. Mud breakdown is usually accompanied by changes in the composition of the mud and subsequent loss of properties required by the mud to perform its functions optimally. Water-based muds are cost effective and environmentally compatible but degrade at higher temperatures. Thus, the need for continuous research for water-based muds with improved performance that can meet the technical requirements of drilling at higher temperatures. This study investigated the effects of two nanomaterials, Multi-Walled Carbon Nanotubes and Iron (II, III) Oxide (Fe3O4) on the filtration and rheological properties of WBMs at elevated temperature and pressure (150 degrees C and 500 psi). Conventional additives were used with the nanomaterials at 0.2, 0.5 and 0.8 wt% concentrations to prepare the nano-mud systems which were aged in a static oven at 150 degrees C for 16 hours before conducting filtration tests at 500 psi and 150 degrees C and rheological tests at ambient temperature and pressure. The morphology of the filter cake samples was investigated using SEM and the permeability was obtained using an existing correlation. The nanomaterials enhanced the filtration properties with carbon nano tube muds exhibiting considerable improvement at all concentrations. The highest improvement was obtained with 0.8 wt% Multi-Walled Carbon Nanotubes with a 15.79 % reduction in filtrate volume relative to the base mud while a slight improvement was achieved with 0.2 wt% Fe3O4. The carbon nano tube mud systems also gave lower filter cake thicknesses and permeability values relative to the base mud and the Fe3O4 system. The nanomud samples exhibited lower rheological properties relative to the base mud for all the measured parameters (10-second gel strength, 10-minute gel strength, yield point and plastic viscosity) indicating improved dispersion of the mud particles. The results obtained indicate the suitability of these nanomaterials for the modification of water-based mud properties at elevated temperature and pressure conditions.