Challenge:
Deepwater well construction often faces extremely narrow mud windows, making conventional single-gradient drilling unsafe and uneconomical. Excessive casing strings, lost circulation, and formation instability increase costs and risk. Managed Pressure Drilling (MPD) helps reduce these issues, but its effectiveness is limited when applied at great water depths due to hydrostatic constraints and system complexity.
Solution:
Ultradeep Energy, in collaboration with international partners, conducted pilot-scale laboratory and field tests to validate a Dual Gradient Drilling (DGD) system based on the Continuous Annular Pressure Management (CAPM) concept. The key innovation involved the use of a decanter centrifuge capable of separating drilling mud into light and heavy fractions directly on the rig. These fractions were then re-circulated to create a dual gradient pressure profile inside the wellbore.
Tests were carried out using multiple centrifuge configurations, including the Sharples P-5000, achieving flow rates above 500 GPM while maintaining stable mud properties. The process proved the feasibility of continuously generating two distinct mud weights without chemical additives or degradation of rheology.
Results:
- Successful separation of drilling mud into 7.3 ppg light-weight and 12–18 ppg heavy-weight fractions.
- Verified centrifuge scalability for industrial deepwater use (>20-inch bowl diameter).
- Demonstrated system stability for both oil- and water-based muds.
- Confirmed the potential for up to 40% reduction in well construction cost through fewer casing strings, faster drilling, and improved pressure management.
Impact:
The CAPM-based Dual Gradient Drilling approach offers a practical, surface-based alternative to subsea pumping systems. By enabling real-time control of annular pressure through fluid density management, the technology bridges the gap between MPD and true dual gradient drilling. This innovation expands the operational window for deepwater wells and represents a major step toward the next generation of efficient and safe drilling systems.
Read Full Publication: https://proceedings.socar.az/uploads/pdf/82/+OGP2021SI200585_70_79.pdf
