Investigation of the Impact of Vermiculite on the Properties of Barite-Based Oil Well Cement

In deep formations, it is important to support the casing and isolate the permeable zones by designing cement systems with high density. Appropriate rheology, high strength, low permeability, and low sedimentation are necessary for a successful cement program. Recently, a lot of attention has been given to the use of different materials to improve cement properties. The objective of this study is to examine the impact of using vermiculite on the properties of high-dense cement. A high cement density of 18 ppg was designed using barite as a weighting material. Five concentrations of vermiculite were used (0.1, 0.3, 0.7, 1, and 1.5) and compared with the base cement. The settling tendency of the heavy-weight particle, rheological, mechanical, and petrophysical properties of the five vermiculite-based cement samples and a base cement sample was investigated. The findings indicate that incorporating vermiculite at a concentration of 0.7% was found to improve the cement performance. Nuclear magnetic resource investigation reveals that the addition of 0.7% vermiculite minimizes barite settling. Additionally, the slurry composed of vermiculite exhibits excellent rheology, indicated by lower plastic viscosity (reduction of 8.4%) and higher gel strength (an increase of 12.5%). At this optimum concentration, the compressive strength is increased by 23.5% while the tensile strength is 28.4% higher. Moreover, the cement’s permeability and porosity are reduced by 45.8% and 44.4%, respectively, compared to the base sample. Finally, the vermiculite cement exhibits more flexibility, defined by a lower Young’s modulus and higher Poisson's ratio.