Achieving Zonal Isolation Using Automated Managed Pressure Cementing

Abstract

Abstract With more wells drilled into hydrocarbon bearing formations, operators are forced to drill into challenging plays with narrow pressure margins. Successful drilling in depleted zones with isolated, high-pressured fractures is difficult and requires managed pressure drilling (MPD). Once the well is drilled, the operator should achieve zonal isolation by pumping cement across the zones of concern without inducing lost circulation or gains. Managed pressure cementing (MPC) pumps cement in a hydrostatically underbalanced environment with pressure applied at surface using an automated choke system (ACS) to maintain a target equivalent circulating density (ECD) between the highest pore pressure (PP) and the lowest fracture gradient (FG) of the well. Communication between cementing operations and MPD software allows automatic system adjustment without manual input. The MPD hydraulic model tracks multiple fluids with different densities, rates, and rheological properties throughout the wellbore. A rig pump diverter (RPD) allows for constant bottomhole pressure (BHP) by manipulating the surface choke pressure if unplanned shutdowns occur. Successful MPC operations have been conducted using the ACS in the Paradox Basin with narrow pressure windows and in the Piceance Basin with high reservoir pressure zones. The nature of cement operations can be unpredictable, but through the automatic managed pressure cementing (AMPC) process, a target ECD can be identified and constant BHP maintained to design and deliver dependable barriers tailored to minimize risk and maximize production.