Magnetorheological fluids for oil and gas well application
Cement is used in oil and gas wells to support the casing and prevent fluid migration between formations. Incompetent cementing in a well and the potential subsequent failure of zonal isolation is a significant concern in the oil and gas industry. Insufficient zonal isolation could cause fluid migration resulting in water aquifer contamination and loss of control of well pressure, shortening the life of wells and increasing the risk of well control incidents, which could result in loss of life, economical loss and environmental damage. To achieve good cementation and guarantee zonal isolation during the lifetime of the well, significant technical challenges need to be overcome. Such challenges are associated with guaranteeing proper fluid-cement displacement, preventing gas migration, and maintaining cement integrity during all phases of well life (drilling, completion/stimulation, production, abandonment). Magnetorheological (MR) fluids (cement-based or non cement-based) can potentially be used to tackle these challenges for applications in oil and gas wells. The rheological properties and flow direction of MR fluids can be controlled by the application of a magnetic field. During the primary cementing process, it is important to displace the drilling fluid and spacer fluid out of the annulus with cement in order to obtain enough strength after cement hydration. This study shows that by applying a magnetic field, the MR cement-based fluid can be guided to achieve more uniform displacement and to increase the displacement efficiency. The results also show that an MR fluid can be used as a flow prevention seal and has the ability to hold pressure, due to its instantaneous stiffening effect when the magnetic field is applied. This can be applied to avoid or remediate annular fluid flow and gas migration, form temporary top-, bottom- or straddle packers, and combine with BOPs for instantaneous pressure control. During the production of a well, the cement in the annulus can experience various severe conditions, which can lead to cracking, de-bonding and shear failure of the cement. The magnetic properties of MR cement-based fluid provide a possible way to evaluate the quality of cement, detect cracking in cement and monitor the health of the cement annulus using non-destructive testing with magnetic methods.