Designing underbalanced drilling operations for dynamic effects
- RF-Rogaland Research, Bergen (Norway)
- Shell RTS, Rijswijk (Netherlands)
- Agip Spa, Milano (Italy)
- Elf Aquitaine, Pau (France)
In most underbalanced drilling operations, Nitrogen or other type of gas is used to lift the annular hydrostatic column. The gas can be introduced into the well through several means, e.g., drillstring gas injection, annulus gas injection via parasite string/casing. Due to the high compressibility nature of gaseous phase and interruptions to the system, the flowing system is a non-steady state one, especially when jointed pipes are used. This is experienced by the varying liquid and gas flow-out rates and the spikes in the bottomhole pressure. These dynamic pressures have been observed and documented in field UBD operations. This paper will present an extensive examination of the dynamic effects during an underbalanced operation. The dynamic effects are often associated with drilling operations, like starting/stopping circulation, gas injection kick-in, changing fluids circulation rates, making connections, tripping, and deployment of BHA and downhole tools. Secondly, the authors present the design considerations that are necessary to avoid the excessive peak loading of the surface facilities, the excessive wellhead pressures, and accidental overbalanced situations downhole. These are developed based on the field experience and simulation results from a dynamic underbalanced drilling simulator. The authors also demonstrate how a dynamic underbalanced drilling simulator can be used to improve the understanding of the physical process involved and be useful in designing operations.
- OSTI ID:
- 485042
- Report Number(s):
- CONF-970146-; ISBN 1-890277-02-9; TRN: IM9727%%210
- Resource Relation:
- Conference: Energy week `97 conference & exhibition, Houston, TX (United States), 28-30 Jan 1997; Other Information: PBD: 1997; Related Information: Is Part Of 8. annual international energy week conference and exhibition: Conference papers. Book 3: Drilling and production operations; PB: 336 p.
- Country of Publication:
- United States
- Language:
- English
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