Abstract
Cement losses into fractures may have detrimental effect on the height of the cement sheath built in the annulus after pumping a pre-defined volume of cement slurry. On the other hand, they might help ensure zonal isolation in CO2 storage sites by reducing permeability of the fracture network in the cap rock, at least in the near-well area. A simple, engineering model of a lost-circulation event during cementing is used to demonstrate how wider fractures result in greater losses, with the radius of the cement bank (formed after pumping a given slurry volume) being approximately proportional to the fracture width. Thicker cement results in smaller losses, but may produce higher bottomhole pressures, thereby exacerbating cement losses.