Lost Circulation in Primary Well Cementing

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.