Summary
A new water-based mud system was successfully introduced as a
high-performance, environmentally compliant alternative to oil and synthetic
emulsion-based muds (OBM/SBM). Historically, emulsion muds have been the
systems of choice when drilling challenging onshore, continental shelf, and
deepwater wells to minimize risk, maximize drilling performance, and reduce
costs. However, environmental constraints, a high frequency of lost
circulation, and the high unit cost of emulsion systems sometimes negate the
benefits of their use. Conventional water-based muds (WBM) offer the
benefits of environmental compliance, attractive logistics, and a relatively
low unit cost but consistently fail to approach the drilling performance of OBM
and SBM.
The new high-performance, water-based mud (HPWBM) is designed to close the
significant drilling performance gap between conventional WBM and
emulsion-based mud systems. The system has undergone extensive field
testing on very challenging onshore, deepwater, and continental shelf wells
that would otherwise have been drilled with oil or synthetic-based muds.
This paper provides a detailed, technical overview of the new system, discusses
its inherent environmental advantages, and presents case histories comparing
performance to offset wells drilled with emulsion and conventional WBM
systems.
Introduction
The industry is increasingly drilling more technically challenging and
difficult wells. Exploration and development operations have expanded
globally as the economics of exploring and producing for oil and gas have
improved with advancements in drilling technology. Advanced drilling operations
such as deep shelf, extended reach, horizontal, and deepwater are technically
challenging, inherently risky, and expensive. OBM and SBM have many inherent
advantages over water-based drilling fluids, including temperature stability,
tolerance to contamination, and corrosion protection. However, the fluid
attributes of concern in this discussion are those most directly related to
drilling performance and environmental issues. With consideration to
reducing drilling problems such as torque and drag, stuck pipe, low
rates-of-penetration, and wellbore stability, these wells are generally drilled
with emulsion-based muds.
Environmental legislation governing drilling waste is continually
restricting the discharge limits of spent muds and drilled cuttings.
Operators are challenged with achieving a balance between minimizing the
potential environmental impact of the drilling fluid against drilling
objectives. The inherent advantages provided by emulsion muds are increasingly
being offset by environmental compliance restrictions.
© 2006. Society of Petroleum Engineers
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History
- Original manuscript received:
2 November 2004
- Revised manuscript received:
12 September 2006
- Manuscript approved:
24 September 2006
- Version of record:
20 December 2006
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