Study On Geological Characteristics And Main Controlling Factors Of Chang2 Reservoir In LC Oilfield

According to a large number of drilling,well logging,mud logging and experimental analysis data,using multi-disciplinary geological theory and fine well stratigraphic comparison of dense well network and large-scale mapping of dense well network,the geological characteristics and main controlling factors of Chang2 reservoir in LC oilfield are comprehensively analyzed.The results show that the Chang2 oil and gas accumulation in LC oilfield is mainly controlled by structure,and the sedimentary,reservoir and cap rock coordination structures promote oil and gas accumulation.The entire structure of the study area is westward,and it is a large nasal fold uplift belt that is tipped to the northwest.A low-lying belt near the north-south direction develops in the eastern part of the study area,forming a large structural trap.The development of small high-angle normal faults in the southeastern part of the study area has important control and influence on the strengthening of Uplift and trap at the top of nasal fold structure in the southeastern part of the area.At the same time,the upper and lower strata are communicated to make the oil and gas enter the Chang21 small layer;There are many long axial nose structures in different directions,low amplitude uplift structures and large uplift structures over faults in the southeast of the area,which provide a favorable place for oil and gas migration and enrichment.The oil and gas is distributed in the north of the fault(the main body of the structure)in the Chang22 small layers,and in the south of the fault in the Chang21 small layers.Braided river deposits and thick massive fine sandstones are developed in the study area,which provide a good reservoir for oil and gas storage.At the top of Chang22,the thickness of mudstone is stable,and the dense layer is developed underneath.The two are mutually configured,providing a good cap rock for oil and gas.At the same time,it also causes Chang21 to show no oil and gas to the north of the fault(the main body of the structure).The interlayer is widely developed,which aggravates the complexity of the reservoir.Oil and gas in the Chang21 small layer is blocked by the top mudstone and the lateral dense layer.The oil and gas in the study area is mainly controlled by structure,and the influence of sediment and reservoir is relatively small;the reservoir type is mainly structural reservoir and lithology-structural reservoir.