Concession contract # 2-85 refers to "Xan field" (47 drilled wells), whose exploration started in the mid 1950s. This contract was initially subscribed with the Basic Resources company, founded in the 1960s by John D. Park, one of the lawyers that worked in the Guatemalan Oil Code after the counter-revolution in 1954. Basic Resources started exploring possible oil wells during the 1970s and began the commercial production in the 1980s, in the middle of the Guatemala Civil War. During the 1970s, Basic Resources joins "Operación Conjunta", which is a combined effort led by the French public company Elf Aquitaine.