The Madura working area is based on the Indonesian Sedimentary Basin Map by the Geological Agency in 2009 and 2020, the study area is included in the sedimentary basin and with code 29, namely the basin with the name North East Java.

From geochemical data (TOC, pyrolysis, and Hydrogen index), the southern part of the study site has potential as mature source rock in Kujung shale, carbonaceous shale, parts of Kujung III shale and coal, parts of CD sand shale, Ngimbang coal and Ngimbang shale. Where this source rock is dominated by type II and III source rocks, while based on the TOC vs S2 cross images the source rock has the potential to produce oil, gas and a mixture of oil and gas. Meanwhile, in the northern part of the study location, the source rock is still in an early mature condition, as seen in the results of the analysis of vitrinite reflectance and spore color index in the Alpha-1 well. From the results of formation tests, gas reading and fluorescence, Kujung I, Kujung II, Kujung III, Poleng/CD, and Ngimbang and even basements found indications of the presence of hydrocarbons, so these formations can act as reservoirs and seals with regional seals ( Middle Miocene) thick Tuban shale was deposited and spread in all wells.