Study On Palaeogene Reservoir Characteristics Of The In Western Tanhai Sag, Liao He Oilfield

For the exploration of oil reservoirs in The Liao he western depression, it is of great significance to study clasolite,to study on it’s reservoirs characteristic and control factors, then according to them, to find the most favorable distribution area of oil bearing reservoirs. Based on the Palaeogene’sedimentary facies, intrafacies and micro-facies; The sand-body of different genetic type and principal control factors, after that delineated The distribution of high-quality reservoirs.The study on Palaeogene’s sedimentary facies show that this area mostly develop seven types of sedimentary facies, river, distributary delta, fan delta, nearshore subaqueous fan, laka, shoal, fan delta plane, advancing edge, bathile, meandering river, braided river, parfacies, river, channel sandbodies, river mouth bars, distal bars, delta front sheet sand and sublacustrine fan, the major reservoir sand-body types arefan delta and distributary delta. through analyzing different sedimentary facies and micro-facies’physical properties. Basically are porosity and permeability, we gain an understanding of the this region’s reservoir ability, of which the fan delta and braided river deltas sandstone’s physical properties are the best, tt is determined that the major reservoirs in the studied area are of high pore and high permeability, high pore and medium permeability, the next is riverway, then is the fan delta sandstone reservoir, mainly are medium pore and medium permeability. Fan deltas and braided river deltas’sandbodies are basically distributary channel, it is the depression’s most important reservoir.The result shows that the diagenesis stage of the reserviors are fron B substage of early Diagenesis to A substage of late Diagenesis. And the diagenesis include mechanic compaction,cementation,dissolution and replacement. To explore the division of the types of diagenesis and the effect of the reservoirs, the first secondary dissolution pore is basically connected to eogenetic carbonate cement and formed by the dissolution of feldspar; the second secondary dissolution pore might be controlled by siliceous cement and silicolites(silexite). The Liao he western depression’s clasolite reservoirs quality is controlled by sedimentary facies, clasolite, the origin of deposits and diagenesis. On those basis we studied the Palaeogene system’s major intervals, which indicated that the up-third member of the Dongying Formation’s favorable reservoir types are distributary delta and delta,which mainly spread over the Kuihuadao oilfield, the Sun Island, Bijialing and Hainan; the down-third member of the Dongying Formation’s favorable reservoir types are also distributary delta and delta, which mainly spread over theBijialing, Hainan, Kuihuadao oilfield and Longwangmiao; the first member of the Shahejie Formation’s favorable reservoir type is fan delta, which mainly spread over the western depression, it is one of the Bijialing’s major reservoir; the second member of the Shahejie Formation’s favorable reservoir type is fan delta-sublacustrine fan, which mainly spread over the western ramp of western sag on Liao he basin and it’s inferior slope break.