Pioneer, which has about 230,000 acres in the Eagle Ford Basin according to its website, sold a 45 percent interest in the property to Reliance for $1.2 billion in 2010. The Eagle Ford Basin asset is a three-way joint venture between Mumbai, India-based Reliance; Irving, Texas-based Pioneer, and a division of Mexico's Alpha SAB de CV to help sell its 45 percent stake, the sources said, asking not to be named because the matter is not public.