Distribution Pattern of Pay Zones in the Complex Dong- zhuang Fault Block Oilfield

Dongzhuang oilfield, located in the southwest of Nanyang depression, is a complex fault block oilfield that developed in an anticlinal setting and was cut by a group of south - dipping formal faults with trends parallel with the long axis of the anticline. The reservoirs with porosity of 14%-15% and permeability of (10. 5-28. 0) + 10-3 tan are mainly frontal sandbodies of the Shayan delta in the northwest direction. This anticline is a swell in the depressed area and has adequate source rocks. It controls the area of hydrocarbon enrichment and the sandbodies control the degree of hydrocarbon enrichment, while the faults function as channels for hydrocarbon redistribution and as sealing. The pay zones are 2,210 m to 2,700 m deep; the oil- bearing interval is about 500m thick; the number of pay zones is 3 to 5; and the averaged single layer thickness is 10 m to 20 m. The fault block in the northern limb of the anticline has a hydrocarbon column of 60 m to 150 m high and an oil - bearing area of 0. 5-0. 8km2, while that in the southern limb has a relatively small oil - bearing area. Based on the geological knowledge of Dongzhuang oilfield, 4 appraisal wells are drilled to materialize an oil - bearing area of 4. 9 km2 and proved geological reserves of 2. 59 million tons.