Abstract
For a number of years the E&P industry has sought to prove the feasibility of monobore expandable liner extensions as an advantageous alternative to the "telescoping" nature of conventional casing designs (Figure 1). Collaboration between an operator and a supplier has produced a system that accomplishes this purpose for a 9 5/8" or 9 7/8" parent casing string to maintain 8 ½" drift post-expansion. Utilization of this well construction product can be planned as either a basis of casing design, or as a planned contingency.
The objective and value of the monobore extension enables the operator to implement one more casing string, without reducing hole size. As a basis of design, this technology provides the option for the operator to begin well construction with one smaller casing size, which may drive down costs significantly, especially in high cost drilling and "floater" drilling programs. As a contingency, the product can isolate trouble zones such as reactive shales, sub-salt rubble zones, and low fracture gradient transitions without being forced to reduce casing size and subsequent drilled hole size. This capability can yield immeasurable benefits when retaining hole size means being able to either evaluate the reservoir as fully as desired, or to produce wells at rates deemed commercially necessary and optimum.
The technology development collaboration produced a one-trip, top-down expansion system that was developed, tested and proved the technical feasibility of the expandable monobore liner extension concept.
This paper details:
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Key System Features and Benefits
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System Development
Downhole recess shoe qualification
Casing selection qualification
Zonal Isolation Requirements
Monobore liner extension selection, one trip system
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Field Trial
Pre-planning
Expansion Process
Post deployment results
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Planned Contingency Applications
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Casing BOD (Basis of Design) Applications
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Summary
