First Comingled Well in South Kuwait Employing Managed Pressure Drilling Technics to Mitigate Drilling Hazards While Drilling, Running and Cementing 5 Inch Production Liner Based on Real Time Data

Abstract

Successfully drill, run, and cement liner throughout 2946′ of 6 ½″ sidetrack section in Burgan Field. Normally planned in two different segments 9 ¼″ and 6 ½″ HS. Mitigating all drilling hazards throughout a high uncertainty pore pressure regime and natural fractured limestone reservoir using Managed Pressure Drilling (MPD).

To achieve this challenging objective, an effective strategy was developed by Weatherford MPD, based on log and pressure data correlations obtained by offset wells previously drilled to identify and mitigate risks while drilling, run, and cement production liner. The strategy consisted in using only two mud weights with MPD real-time bottom hole pressure assessments while drilling from 10714 ft MD/10441 ft TVD (Najma Formation) to 13660 ft MD/11937 ft TVD passing across Sargelu, Dharuma and Upper Marrat, formations usually related with high pressure zones, and Middle - Lower Marrat, usually marked as Low pore pressure zone.

The plan involves drilling the section using light MW, which is statically underbalanced. To achieve optimal performance, applying surface back pressure to create a slight overbalance. This approach will facilitate better management of pre-pressure conditions during the drilling process. Utilizing an accurate real-time hydraulics model while cementing is very critical to stay within pressure window across naturally fracture zones. During Managed Pressure Cement (MPC), Surface Back Pressure is applied to avoid wellbore pressure variations during cement slurry setting due to downhole pressure changes.

These techniques, MP Drilling, running completion and cementing, provided significant results and made the overall well construction process more efficient. The 6 ½″ drilling phase was completed, and the target depth was reached within 15 days from 10714 ft MD to 13660 ft MD. The MPD technology significantly helped optimize the drilling and casing process in Burgan Field, South Kuwait. The target was achieved by precisely managing the wellbore pressure while drilling, running the liner, and cement within a fine window with no drilling hazards recorded such as gain, losses or pipe stuck. Based on the successful outcome, The implementation of automated MPD enabled to drill wells normally undrillable, making possible navigate through a long hole section with highly uncertain operative window using less mud weight changes, running and cement only one production liner. MPD is a tool that can be used to simplify drillings operations at the same time applying important cost reduction to develop wells.

Drill, Run and Cement the Production Liner successfully across almost 3000 ft of High-Low pressure and fracture zones in Burgan Field, South Kuwait using Managed Pressure Drilling demonstrate a significant improvement not only related to the operative costs but also in the simplification that means using less mud weight changes, 80% less compared with offset wells drilled conventionally, and less casings running.