Research On High Resolution Sequence Stratigraphy And Reservoir Characteristics Of Yageliemu Formation In Yakela

On the basis of the former' achievements and regional research, based on cores, well logging, seismic data, mainly by means of advanced theorise of sedimentoligy, high resolution sequence stratigraphic theory and reservoirs prediction, the paper aims to studying on sub-zone correlation,relationship between sedimentary facies and reservoirs, distribution of reservoirs, distribution of interlayer,reservoir heterogeneity of Yageliemu Formation.Though establishing a model to reflect the relation of well-logging facies with corresponding sedimentary facies, the author analyses the sedimentary facies in detail. According to the results, it is considered that the research formation belongs to fan delta system and braided river delta depositional system and some microfacies are branch channel, flood plain, tributary bay, subaqueous distributary channel,river mouth bar. and characteristics of depositional facies of 1～3 sand sets in plane, is discussedIt is diveded into one long-term, three middle-term and ten～twelve short-term cyclic sequences, according to analysis of sequence structure and stracking pattern of base-level cycle in sedimentary dynamic. In this paper, which, is dicussed, the structures, distribution sedimentary cycle and stacking patterns of different cycle sequences, in which the characteristics of different type of sand in detail. Through establishtion of the chrono-stratigraghic framework, middle-term and short-term cycle sequence framework, the sands are directed into these isochronous stratigraphy framework, and isochronous tracing correlation is set up.According to theorise of sedimentoligy and high resolution sequence stratigraphic theory, we analyse the sand body distribution, types, characteristics and distribution of interlayer. It is considered that in verticale distribution of sand body and interlayer is obviously influenced by middle-term,long-term cyclic sequences, and in plane their characteristics are resulted from long-term cyclic sequencse. Correlating datum cycle and characteristics of sand bodies and interlayer, We consider that the first sand zones is correspond to MSC1,sand body thickness is big and interlayer is not nearly developed; The second sand zones is correspond to early-middle of up half ascending of MSC2, which belongs to late up half ascending of long-term cyclic sequences, sand body thickness is small; The third sand zones is correspond to the early-middle up half ascending of MSC3, which locates in the early up half ascending of long-term cyclic sequences, superpositional sand body is developed. Interlayers Of type I~1 , formed in subaqueous tributary bay sedimentary microfacies, were developed in middle and lower of middle-term cycle sequence; Interlayers Of type II~1 ,formed in tributary bay, were developed in down of up half ascending of middle-term cycle sequence; Interlayers Of type II~2,formed in flood plain and fan prodelta,were developed in transfer cycles of up half ascending and down half ascending of middle-term,long-term cycle sequence.The reservoir heterogeneity of 1～3 members is strong, and controlled by long-term datum cycle.Through indentify of thin sections and cast thin sections, the results shows reservoir property is maily secondary. Pore type is mainly dissolution intragranual pore, intergranual pore, dissolution seam, stamp hole, and crystal pore.Combined with analysis of lithofacies-paleographical mapping sedimentary facies and sand distribution of middle-term cycle sequences and seismic inversion, it indicates that the first sand zones is the thickest, and the direction of main sediment sources is southwest and northwest; the second sand zones is thin, the thickest in well S6, and the direction of main sediment sources is northeast in well Y3; the third sand zones is thicker than the second one, and the thickest in well S82 which is southwest, and become thiner from the southwest area to the middle area.