Noble Energy's investments in West Africa began in the early 1990s and now represent a significant component of our international portfolio. Our production activities began with our 34 percent working interest in the Alba field, offshore Equatorial Guinea. In addition to natural gas and crude oil production, related operations include an LPG processing plant where liquids are recovered and a methanol plant. Natural gas produced from the field is sold to the LPG and methanol plants as well as a third-party LNG facility.
We are actively engaged in both development and exploration activities offshore Equatorial Guinea, with operated working interests of 45 percent in Block O and 38 percent in Block I. We also have a 50 percent interest offshore Cameroon in the YoYo mining concession and Tilapia exploration block. Over the last few years, we have achieved tremendous exploration success in the region, discovering a combined 334 MMBoe, net to Noble Energy, in multiple oil and gas-condensate reservoirs. The lineup of exploration discoveries is set to deliver multi-year growth in production and cash flow for Noble Energy.
In 2009, we sanctioned the Aseng oil project (formerly Benita) in Block I and brought it to production in November 2011, seven months ahead of schedule. The newly constructed FPSO, a floating production, storage and offloading vessel, is capable of producing 80 MBbl/d of oil and 170 MMcf/d of natural gas. The initial production rate was 50 MBbl/d, 17 MBbl/d net to Noble Energy, and was increased to a maximum production rate of 70 MBbl/d. Alen is a condensate gas-cycling project (formerly known as Belinda) sanctioned in 2010. We have a 47 percent working interest in Alen. We are also progressing additional liquid discoveries, as well as integrated gas monetization efforts for our natural gas discoveries. We announced an oil discovery at Carla in the 4th quarter of 2011 and are actively appraising the discovery which is located below the Alen field. Diega, a condensate and crude oil discovery, is scheduled for appraisal following work at Carla.