Noble Energy’s high-quality portfolio is distinguished by its diversity, exploration component and sizeable international holdings. Each asset fills an important role in a portfolio that balances lower-risk development projects with high-potential exploration activities. With an asset mix that includes both United States and international opportunities in oil and natural gas, we have many options that allow us to employ our knowledge, replicate our successes and create value for many years to come.
Our onshore assets in the U.S. deliver steady, consistent and predictable results. In the DJ Basin we have a very successful legacy of resource development and continue to focus on improving operating efficiencies, lowering costs and minimizing footprint. Noble Energy enhanced its onshore U.S. position in 2011 by acquiring Marcellus Shale properties in southwest Pennsylvania and northwest West Virginia, which provide significant exposure to the core onshore U.S. natural gas play.
Exploration and development activities in the deepwater Gulf of Mexico focus on significant opportunities where projects can be a source of medium and long-term growth. With key positions offshore Equatorial Guinea and the Eastern Mediterranean (Israel and Cyprus) our international business provides long-lived production in basins with significant running-room.
Our exploration program has delivered a significant lineup of major development projects over the last few years, as we appraise and develop the substantial resources discovered in our core areas. Multiple major projects were brought online in 2013. Tamar (Israel), Alen (Equatorial Guinea), and the Wells Ranch Central Processing Facility (DJ Basin) all commenced operation during the year.
In addition, we have built a large inventory of further exploration upside that has the potential to deliver continued growth for our company. A number of significant opportunities build on our core operational areas where substantial success has already been achieved: onshore in the U.S., the deepwater Gulf of Mexico, offshore West Africa and offshore Eastern Mediterranean. In addition, we are focused on new basin potential in multiple new venture areas.