Claromecó Basin (Carboniferous-Permian) is considereda frontier basin due to itslimited geologic knowledge.This basin haseconomic potential based on coal beds and seams and associated methane gas, recorded underground.The aim of this workis to evaluate the economic potential of Tunas Formation in the PANG 0001 well, based on petrographic, diagenetic and fluid inclusion studies in sandy facies. In addition, oleogenetic potential of muddy faces through TOC (total organic carbon) analysis is determined.PANG 0001 well is located in the basin center. In this well Tunas Formation is made of medium to fine sized sandstones, tuffs, mudrocks, carbonaceous mudrocks and coal levels. Identified diagenetic processes include mechanical compaction, cement precipitation, alteration, replacement, dissolution and late tectonic fracturing. Physical compaction is the predominant factor, along with precipitation of diagenetic minerals reduce porosity and decrease reservoir quality. Secondary porosity is comprised by rock and grain fracture and feldspar and carbonate cement dissolution; its value reaches 0.2 to 0.6%.Fluid inclusions are aqueous, placed mainly in cements,andalsoorganic, with yellow and light blue fluorescence, located in microfractures and veins; those colors indicate presence of liquid to wet gas hydrocarbons and dry gas (methane) respectively. During early diagenesis precipitation of carbonate cements and mechanical compaction of sandy facies were dominant. Poral space was reduced by these diagenetic processes. Mesogenesis conditions are proper to generate hydrocarbons and an acid environment to dissolve feldspars and carbonate cement. Subsequent compaction, tectonic events and fluid pressure generate secondary porosity, increase the reservoir quality and allow hydrocarbon migration. Finally, quartz and feldspars overgrowth, late calcite cement precipitation and fractures healing occur during late mesogenesis and reduce porosity. Total organic carbon values are 0.5-5% in mudrocks and 12-26% for carbonaceous mudrocks.Based on previous results, it can be concluded that Tunas Formation has potential as source rock in muddy levels and as reservoir in sandy levels, so the formation can be considered as a potential speculative petroleum system: Tunas-Tunas (?).