Research The Sequence Stratigraphy And Depositional Systmes Of Lower Cretaceous Formation Of Wuerxun Depression Of HaiLaer Basin

In this paper, the classic sequence stratigraphy and sedimentology principles as the theoretical basis, use seismic data, log curve, core, etc., combined with regional tectonic and sedimentary background of Wuerxun depression, established the the sequence stratigraphic division scheme of Lower Cretaceous formation in Wuerxun depression.The Wuerxun Depression of the Lower Cretaceous formation is divided into one first-order sequence, four second-order sequences, seven third-order sequence;the Lower Cretaceous sedimentary cycle as a one-order seqence,from the initial basin lake transgression, to the last uplift, shallow, filling the basin evolution can be seen as a first-class sedimentary sequence; four secondary sequences are widely limited by the five major unconformity,first-order Sequence and secondary-level sequence are closely related to tectonization,third-order sequences is limited by the partial unconformity and its corresponding unconformity and sedimentary cyclicity.Using Logging data,seismic data and core data identify and tracking different scale sequence boundaries,from single well, and multitude wells sequence comparison,establish the research area sequence stratigraphic framework,and research the sequence stratigraphic distribution within the framework.Based on sequence stratigraphy research,using curve and core data binding of region of tectonic and sedimentary background,made the research area facies analysis,from single well core observation,use of the corresponding curve feature summary log phase factor characteristic of sedimentary facies; identified alluvial fan, fan delta, braided river delta, meandering river delta, lake floor fan, lake sedimentary system in Wuerxun depression.Re-use of single well facies analysis and multitude wells facies analysis,from point to the line then to surface facies deduction.Using third-order sequence as units,analysis sedimentary system in sequence stratigraphic framework,definitiy different sedimentary facies surface characteristics in Wuerxun depression.And summed up the sedimentary evolution that the Wuerxun depression early development of mountain basin,filling phase is mainly alluvial fan-fan delta-shallow lake sedimentary system,after that passive rift phase from the alluvial basin fan-fan delta-lacustrine depositional system of the transition to a braided river delta-lacustrine depositional system; active rift sedimentary rift basin filling models dominated braided river delta;then rift to depression transform phase,the basin filling by braided delta and river meandering river delta. Through analysis different sequence research area facies,defined the distribution of source rock and reservoir and cap rock...