The Cellino Formation is a lower Pliocene submarine fan system that forms extensive subsurface reservoir rocks. The sequence crops out in central Italy and exhibits a definite geometric pattern of lateral fan accretion. The vertical and lateral sequences are interpreted from electric logs and supported by field observations. The Cellino Formation consists of a series of different turbidite facies associations. The lower part of the Cellino Formation here has been cut and deeply eroded in the northern part. A new sequence follows, which activates the eastern migration of the fan system and deposits facies. Postdepositional deformation decreases in the area in intensity eastward. Carbonate cements sandstone layers in the southwest part of the area. Associated hydrocarbons were trapped in outer fan lobes which were deformed into an anticline. The thin shale beds provide the cap rocks of the turbidite reservoirs. Many of the depositional lobes have their individual gas-water contacts.--Modified journal abstract.