Computer simulation technology has been widely applied in many drilling
engineering areas to simulate drilling engineering problems and optimization,
to train engineers with real drilling operations and/or to handle rare
applications and accidents.
Among the increasingly applied drilling operations is under-balanced
drilling (UBD). UBD is the drilling process in which the wellbore pressure is
intentionally designed to be lower than the pressure of the formation being
drilled. This results in a higher rate of penetration (ROP) and prevents fluid
losses and related causes of formation damage.
This paper presents the design and development of a UBD simulator, which is
computer software that simulates and integrates the effects of:
- Bottomhole pressure (BHP).
- Minimum volumetric gas and liquid requirement.
- Required backpressure (BP) for required cutting removal to surface and
- Kinematic energy per unit volume used in the hole cleaning
- Stand pipe pressure (SPP).
- Rock drillability.
- Drilling costs per metre.
The goal of the simulator is to enable the user to pre-simulate different
scenarios of the UBD drilling operations; therefore, the ideal optimized
combination of drill bit durability and drilling efficiency, integrating all
UBD operational parameters affecting the overall cost, can be obtained before
the fact. The UBD simulator is designed to simulate most of the basic
technologies of UBD (air, aerated and foam drilling). The goal of the UBD
simulator is to design an effective UBD program by linking the BHP to rock
drillability, which takes into account the effect and degree of under-balance
on the effective rock strength, ROP and $/m that can be optimized for the
operation. The complete UBD optimization integration is shown herein with
illustrations including flowcharts.
© 2010. Society of Petroleum Engineers
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- Original manuscript received:
24 March 2009
- Meeting paper published:
17 June 2009
- Revised manuscript received:
28 April 2010
- Manuscript approved:
29 April 2010
- Published online:
21 June 2010
- Version of record:
1 June 2010