This is a case study of a successful, field-wide implementation of horizontal, barefoot completions in a moderately competent formation - the Alpine Reservoir in Western North Slope, Alaska, Figure 1. A barefoot completion is a borehole without tubular liners and no cemented support - the least costly but riskiest completion strategy. (In this paper, barefoot and unsupported mean the same and are used interchangeably.) The Alpine experience provides a successful example where the benefits of unsupported boreholes outweigh the risks of borehole failure. To date, this aggressive yet simple completion technique has an aggregate length of more than 160,000 ft, all unsupported.

Combined with good drilling practices, the success of barefoot horizontal wells in Alpine is also due to the following petrophysical and geomechanical factors:

  1. Consistent reservoir quality within the layer

  2. Absence of shale-breaks in the producing zone

  3. Moderate strength in normal fault geotectonic setting

  4. Low variability of strength

  5. Linearly elastic behavior

  6. Non-severe, slight weakening when water-saturated

  7. Good permeability retained under post-elastic strains

Keywords:
enhanced recovery, strength, conventional mcf, barefoot completion, alaska, implementation, tangential stress, reservoir characterization, permeability, completion
Subjects:
Wellbore Design, Drilling Operations, Reservoir Characterization, Improved and Enhanced Recovery, Wellbore integrity, Reservoir geomechanics, Miscible methods, Completion Installation and Operations
Copyright 2002, Society of Petroleum Engineers
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