Are there any field development case study sites that focus on upstream exploration and production examples?

Yes. If you mean field development case studies that are centered on upstream oil and gas exploration and production (E&P), there are many well-known examples. These are often used to illustrate reservoir management, drilling, completion, facilities, production optimization, and development planning.

Here are some notable upstream field development case study sites/examples:

Major field development case study examples

• North Sea fields
  Common case studies for offshore development, enhanced recovery, and mature field management.
• Ghawar Field, Saudi Arabia
  A classic example of giant onshore field development, water injection, and reservoir management.
• Wafra Field, Kuwait/Saudi Arabia (Partitioned Zone)
  Often used for heavy oil and enhanced oil recovery case studies.
• Cantarell Field, Mexico
  Frequently discussed for pressure maintenance, nitrogen injection, and production decline management.
• Kashagan Field, Kazakhstan
  A major offshore development case study involving harsh environment engineering and complex project execution.
• Bakken Shale, USA
  Used for unconventional upstream development, horizontal drilling, and multistage fracturing.
• Permian Basin, USA
  A large set of case studies on shale development, drilling efficiency, and optimization.
• Deepwater Gulf of Mexico fields
  Often used for subsea development and deepwater production system case studies.
• Offshore Brazil pre-salt fields
  Common examples for ultra-deepwater development and subsea tiebacks.

What these case studies usually focus on

• reservoir characterization
• exploration-to-development planning
• drilling and completions
• production facilities design
• artificial lift
• enhanced oil recovery
• subsea systems
• decline management
• economics and project execution

If you want actual “sites” with case study collections

There are also organizations and repositories that publish upstream field development cases:

• SPE (Society of Petroleum Engineers) papers and case studies
• OnePetro
• OTC conference papers
• Oil & Gas Journal case histories
• operator technical presentations from companies like Shell, Chevron, BP, ExxonMobil, Saudi Aramco, Petrobras, etc.

If you want, I can also give you:

1. a list of 10 specific upstream field development case studies,
2. a table by region/field type, or
3. links to public case study repositories.