Page 6 - Offshore Well Construction

CHAPTER 2
Well Design Process
Petroleum Extension-The University of Texas at Austin

OVERVIEW
The well construction process can be broken down into five sequential phases of work, as follows:
1. Preliminary well design
2. Detailed well design
3. Prepare drilling program
4. Execute well program
5. Analyze and improve performance
Well design focuses primarily on the preliminary and detailed well design and the preparation of the drilling program.

PRELIMINARY WELL DESIGN
Preliminary well design is essentially a screening stage of the well design process. The major steps are shown below.

Basis of Design Design Options Design Options
Issue Preliminary Reviewed, Created and ReviewedÑ
Basis of Design Challenged, Modified, Valued Preferred Option
and Agreed Identified

Decision to Procurement Well Placed on Move to Detailed
Proceed Initiated Rig Schedule Well Design

Issue Preliminary Basis of Design
Once the geological and geophysical studies have identified a potential well location, the subsurface team will work
up a basis of design. This is the information that gets handed over to the well construction team and forms the basis
of the well design. The basis of design will generally provide information on the following:
• Well name and number
• Well objectives
• Total depth
• Surface location
• Water depth
• Target location
• Target size and tolerance
• Target constraints
• Geological prognosis
• Seismic section
• Expected hydrocarbons
• Anticipated pore pressures
• Anticipated temperature profile
• Offset wells
• Geological hazards (shallow gas, faulting, H S, CO , lease line restrictions, flow lines, etc.)
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• Additional constraints (drilled before a certain date, etc.)
• Evaluation program (details and justification of required wireline logs, coring, and testing)

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