Sedimentary System Research On Putaohua Oil Layer Of Yingtai Area In The South Of Gulong

The first member of Yaojia Formation, Putaohua Reservoir of the lower cretaceous, is the study layer of Yingtai area in South Gulong Region, locating in southern part of Qijia-Gulong sag of the central depressed area of Songliao basin. Although predecessors have done much deeply research on this area, different opinions are still existing. Based on the former studies, guided by the theories of sequence stratigraphy, sedimentology, this dissertation did a more specific division and facies reserch on Putaohua Reservoir, which is very instructive to the reservoir prediction and favorable abundance zone of oil and gas.Based on seismic, well log, core and geologic log data, third-order sequence boundaries SBâ…¢1and SBâ…¢2 corresponding to seismic reflection interfaces T1-1 and T03 were redelimited; extending the method turing on it and developing it into forth-order, fith-order and sixth-order sequence boundaries of Putaohua Reservoir in Yingtai area. And then, high resolution stratigraphic classification was conducted, with one mid-term cycles ( PI reservoir group), three short-term cycles ( PI upper, PI middle, PI lower ) and eight super-short-term cycles(PI1,PI2,PI3,PI4,PI5,PI6,PI7,PI8). Through the division of base level cycles and sequence stratigraphic units (super-short-term cycles), sequence stratigraphic contrast and sequence stratigraphic framework of Putaohua Reservoir of Yingtai area was accomplished.Source analysis, sedimentary facies types and distribution of sedimentary facies were researched within sequence framework. By means of analyzing color, lithology, types of sedimentary structures, paleontological markers, electrofacies feature and so on ,combined with core and logging data, single well facies, we did a comprehensive study on single well facies, and then confirmed types of sedimentary faces in the study area which develops delta facies and lake facies in Putaohua oil layer. Delta front subfacies is the main subfacies, of which microfacies types mainly are underwater distributary channel, mouth bar, sand sheet, sub-sea crevasse channel and underwater distributary interchannels. Lake facies mainly develops shore-shallow lake microfacies. Heavy minerals data and sandstone content revealed that controlled mainly by the western provenance system and accidentally by the northern provenance system, source rock of this study area is mainly acidic magmatic rocks. On the basis of the study above, profile contrast were implemented and eight phase-plane diagrams in super-short-term cycle units were drawed, which established the time and space evolution of sedimentary system of this area. What we have achieved makes us believe that Putaohua reservoir deposits in a deepening water, sand body fading retrograding sedimentary sequence.