Drill gas storage wells
The State Oil Company of Azerbaijan Republic (SOCAR) planned to drill more than 20 new wells into a depleted gas zone in the Garadagh field—with a good formation seal above and below the zone—and use it for offshore gas storage. The tophole sections of the wells had to be drilled straight and in-gauge in the soft formation to avoid casing running problems. SOCAR would also have to maintain a low equivalent circulating density (ECD).
Enlarge hole to run casing
Schlumberger designed a BHA to enlarge the 17 1/2-in section to 20 in. The BHA incorporated the Rhino XC on-demand hydraulically actuated reamer with a PowerPak straight hole motor and a soft-formation milled tooth roller cone drill bit from Smith Bits, a Schlumberger company.
In this straight-hole application, the PowerPak motor maximized ROP with the aggressive roller cone bit. The Rhino XC reamer, which was chosen because of its reliability in drilling while enlarging the hole, provided complete control of reamer activation. Its one-piece, balanced design increased torque and load-carrying capacity while producing the in-gauge wellbore for improved casing running.
The Rhino XC reamer can be hydraulically activated and deactivated multiple times on a run. It is valuable for applications where the use of pumpdown balls or darts is not desirable or where closing the underreamer without having to trip out of the hole is important to establish formation tops and drill through unconsolidated shale, fault zones, or hard stringers.
Drill and underream in one run
After Well 476 was spudded, the BHA drilled the 17 1/2-in hole section from 100 m to 1,089 m in a single run while enlarging the hole to 20 in. As a result, a high-quality in-gauge hole was produced, which facilitated casing running and reduced ECD. During the run, the Rhino XC reamer was activated and deactivated eight times. Its reliable performance prompted SOCAR to request it for use in other wells.