Sequence And Seismic Sedimentology Analysis Of Toutunhe Formation In Fudong Slope Area Of Junggar Basin

East of Fukang area in east Junngar Basin is the typical terrestrial-ramp, in which Toutunhe Formation of Jurassic is one of most important exploration atrata with good exploration benefit, received widespread attention. Traps with a distinct structure are less developed for weaker influenced by tectonic movement, and lithologic and stratigraphic-lithologic composite oil reservoirs are main reservoirs controlled by channel sand body. Because stratigraphic and lithologic reservoirs easily developed in sand strata with lateral stability, wide distribution and good reservoir properties, so channel sands are main targets for future exploration. With deeper development of exploration, uncertainty of reservoir sand scale and boundary becomes distinct that hinders comprehensive assessment and efficient exploration and development. According these problems, high-resolution sequence stratigraphic framework should be built base on drilling, logging, well logging, lithology, oil testing and seismic data to analyse lithofacies paleogeography of every member in Toutunhe Formation, then search distribution regularities and characters of reservoir sand by using technique of seismic sedimentology under framework of high-resolution sequence stratigraphic. Through sediment-sequence analysis, favorable area and reservoirs can be predicted by many seismic attributes technique. Main content and result are as follows:Based on definite analysis of outcrops, drilling cores and logging data, sequence boundaries of third-order, fourth-order and fifth-order are recognized definitely through well drilling and seismic detection and horizon tracing techniques in Fudong slope area, and sequence stratagraphic framework in Fudong slope area is built that divide Toutunhe Formation of Middle-Jurassic into one long-term cycle(LSC1), three middle-term cycles(MSC1~MSC3) and ten short-term cycles(SSC1~SSC10). And developments of sequences are controlled by composite effect of tectonic movement and paleoclimatic change.Structures of developed short-term sequences are different, which can be divided into two main types comprise of upwards “deepening” asymmetric cyclic structure and symmetric cyclic structure; Middle-term sequence structures are mainly incomplete symmetric cyclic structure in which thickness of uprising periods are larger than decreasing periods, some are upwards “deepening” asymmetric cyclic structure; Long-term sequence of inner basin are protected well, which develop incomplete symmetric cyclic structure in which thickness of uprising periods are larger than decreasing periods and asymmetric cyclic structure with large thickness of sediment and stable structure types, lithology and facies.Based on the analysis of rock color, textures, structures, paleontology, seismic facies and logging data, braided delta sedimentary system is mainly developed in Toutunhe formation and lake sedimentary system developed regional. Through sedimentary facies analysis of single well and connecting wells that sub-face of braided delta front is main sedimentary types in Fudong slope area; And based on sedimentary facies characters of Toutunhe Formation, combined with results of previous, sedimentary facies mode of braided delta in Toutunhe Formation of Fudong slope area is finished.Dynamic provenance, plane distribution of sedimentary facies under mid-term sequence stratigraphic framework, sedimentary evolution regularity in short-term sequence and definite analysis of sedimentary character in key short-term cycles have been effectively searched by using many techniques comprise of 90°-phase inversion, stratal slicing, attributes analysis and interpreting with frequency. Results show that Beisantai Salient supplies some sediment for Fudong slope area for Yanshan tectonic movement through stratal slicing; During MSC1 of Toutunhe Formation, braided delta front developed widespread in Fudong slope area, and east region of slope area lifted gradually for Yanshan tectonic movement, sedimentary character of “large front and small plain” appeared in MSC2 and MSC3 of Toutunhe Formation, area of delta plain is broadened, while area of lake is reduced gradually.Make statistics of rock association in different short-term cycles to certain degree of corresponding seismic attributes under high-resolution sequence stratigraphic framework, which reveals sand-seismic response characteristics in condition of different A/S ratio, and build forward mode of drilling geology-geophysical, then make optimization, dimension reduction and fusion on many seismic attributes which can represent sand body in Toutunhe Formation, that scale and distribution regularity in short-term cycles are described, and proved by drilling data.Make relationship between base-level changes and sequence structure changes to reveal differences of sand plane distribution. Sand body with large thickness and good continuity often develops in initial stage of base-level uprising or late initial stage of base-level decreasing, criss-cross character of plane channel are showed obviously, and thick sand body(more than 10 meters) and thicker sand body(more than 20 meters) can be recognized in seismic sections, which effectively improved sand seismic resolution detection and take new thinking and techniques to high efficiency on exploration and development in Toutunhe Formation of Fudong slope area.Results above are helpful for riching high-resolution sequence stratigraphy theory and its application on oil and gas field exploration and development in our country, and have great guiding significance on progressive exploration and development efficiency in Fudong slope area.