Characteristics and controlling factors of volcanic reservoir of Carboniferous in Santanghu Basin

The reservoir characteristics of C2 h and C2 k of Carboniferous in Santanghu Basin are analyzed. It is considered that effective source rock, favorable facies zone and faulted zone, paleo tectonic near petroleum genetative depression and late reformation are the main controlling factors of reservoir accumulation of Carboniferous volcanic rocks in Santanghu Basin. The volcanic reservoir in Santanghu Basin is complex, and petroleum migrated mainly in vertical direction, with limited lateral migration. The effective source rock has a significant controlling effect on oil and gas distribution. Ancient uplift and paleo tectonic provide structural setting for hydrocarbon multi-stage migration and accumulation. Volcanic activity is controlled by deep fault, and fault is the main migration pathway. Oil and gas that generated from the deep fault migrated along fault and fracture to uplift and accumulated there. The upper subfacies of effusive facies is favorable zone for volcanic reservoir. Volcanic breccia has the best reservoir property and oiliness, followed by basalt and andesite. Micro-fracture that generated by tectonic movement and weathering and leaching effectively improved the reservoir space. Oil and gas mainly occurred in volcanic solution pore linked up by fracture. It is pointed out that Malang Sag, Tiaohu Sag, Tiaoshan Sag, Weibei uplift and the thrust belt in the southern margin of Santanghu Basin are the favorable exploration field.