High Resolution Sequence Stratigraphy Of Yanchang 4+5 To 3 Sector In Baibao Area Of Erdos Basin

In this paper, the author synthetically applied continental lake basin high-resolution sequence stratigraphy, sedimentation, well logging, petroleum geology, mathematics geology, etc, on the basis of studying on the core of the well drilling in the district, fully utilize logging well, well drilling core and testing and analyzing materials, adopting well logging-sedimentary facies automatical identification to study the characters of sedimentary facies and sub-facies further. And study sedimentary facies profoundly, and carry on sedimentary facies contrast well to well, to study Yanchang 3 sector and Yanchang 4+5 sector lithofacies palaeogeography character and evolution further.Baibao area lies in the middle-south of the basin, delta deposit was belong to the north set of Jingbian-Wuqi delta and locating at front region. According to observing the core and well logging facies analysis, Yanchang 4+5 sector to Yangchang 3 mainly developed underwater distributary channel, river mouth bars, underwater natural levee, underwater crevasse splay, interdistributary bay, far bars, etc. and some shallow lake subfacies. Among them, underwater distributary channel in delta front was the main facies. Deposit characters have fine succession, however, because of the underwater distributary channel's movement and migration, the scale of the shallow deposits and delta front deposit were different. In research area, Yanchang 4+5 sector to Yanchang 3 underwater distributary channel sandbodys in delta front was north-east to south west, and were separated by interdistributary bay.Yanchang 4+5 sector to Yanchang 3 sector lithofacies palaeogeography pattern was stable, because the constitution background was steady, and the source direction had no change, and supply was abundant. In those sectors the basin development was in lake retreat, and in the period of extinction gradually, and formatted construction delta deposit, but in Yanchang 33 period the sedimentary speed were greater than construction speed, showing that overriding river mouth bars were abundant.On the basis of sedimentary facies division, the author firstly divided super short-term and short-time base-level cycle on well drilling cores, and playback thecores to well logging curves to scale them, and set up different classes of base-level cycles answered to well logging respond models. Finally the author discussed how to use log well curve to divide super short-term and short-time base-level cycle characters, and to set up super short-term and short-term base-level cycle comparison framework, and analyzed sand body origin cause of formation type and spreading rules.