Study On Sequences Stratigraphy And Sedimentary Facies Of Mid-block, Eastern Of Precaspian Basin

Based on great of drilling, logging and seismic data, also applied on the sequences stratigraphy theories and analyzing techniques, the high resolution sequences stratigraphy and sedimentary facies distribution have been studied in mid-block, eastern of precaspian basin.After referring to the past research results and the regional background, started from the tectonics settings, researched the basin evolution history and the structural framework, especially the key point of basin character which controlled the development of sequence and sedimentary process, this thesis found out the basic rules of tectonic evolution and structural framework which affected the strata and sedimentary activities, and also built up seven evolutional stages of Carboniferous in mid-block, eastern of precaspian basin.Referring to the sequences stratigraphy theory, recognized the sequences boundaries and flooding surface on each wells by major unconformity, sedimentary discontinuity, lithological sudden change and the conversion of parasequence stacking pattern. At the same time, analyzed the reflection structure and its response characteristics on seismic, then built up the isochronous stratigraphic framework in studied area which divided the Carboniferous KT-Ⅰand KT-Ⅱformations into five second stage sequence, eleven third stage sequence. What’more, through the correlations between well and well also combined with the sequences tracking on seismic, the developed situation and distribution feature of every sequence in different zones have been studied.sedimentary facies distribution and prediction are carried out under the sequencestratigraphic framework? constrained integrated information. Considered the Carboniferous sedimentary evolution, logging, testing and the drilling cores, thin sections materials, identification features of lithological facies and log phase are concluded. After the sedimentary facies analysis on single well, the sedimentary model of Carboniferous in mid-block is complemented and preliminarily recognized four facies (evaporation platform, restricted platform, est.), eleven subfacies (platform shoal, platform sea, tidal flat, est.), twenty-four mirofacies (oolitic shoal, bioclastic shoal, lime-mud flat, est.). In the plane, sedimentary facies distributed from north to south and changed from west to east. In vertical, sedimentary evolution orders from down to up were shelf—open platform—shelf—open platform—restricted platform—evaporation platform?and?experienced two big sea level dropping and rising process which made up two sedimentary cycles from terrigenous clastic shelf facies to carbonate platform facies. Integated all the materials found that the key point controlled the sedimentary filling process in studied area is tectonic evolution. Under the control of sequences stratigraphic framework, tracked the ranges of the special geological bodies, then started from the external geometry and internal reflection feature of the seismic, took the advantage of seismic attributes analysis, and also combined with the regional tectonic, sedimentary filling and drilling materials, this thesis made the preliminary explain about the special geological bodies. All of the findings carried out the isochronous stratigraphic framework in studied area and under its constraint predicted the sedimentaty facies distribution in every sequence, which provided a scientific basis for depth exploration and development.