Lower Cretaceous Storm Sedimentary Characteristics In The North Troughs Of Bayindulan Sag,Erlian Basin

As an event deposit,storm deposit has different hydrodynamic characteristics from other deposits in its deposition process.In addition,it can also form isochron in the stratigraphic profile,which plays an important role in stratigraphic correlation,especially in the strata lacking fossils.At the same time,it can also provide a basis for the restoration of paleogeographic location,paleo-structure and paleo-environment in the study area.Sag of Erlian basin on the touraine north subsags core observation,well logging and seismic data,the lower cretaceous the storm deposit of Aershan and Tenggeer Formation,analyzes its petrology characteristics and characteristics of sedimentary structure and established the Aershan Formation and Tenggeer Formation storm sedimentary sequences and distribution mode,summed up the storm of the depositional model in the study area and geological significance,It enriches the study of sedimentary facies and storm deposits of the Lower Cretaceous in the study area.According to core observation and well logging curve in the study area,the development of the storm deposits in the study area,nearshore subaqueous fan,fan delta,slump turbidite fan,lake is equal to 5 kinds of sedimentary facies,analyzed storm deposits in the study area,the development has a wash surface,hummocky-depression cross-bedding,truncated structure wavy cross bedding,parallel bedding and,etc.The ideal sedimentation sequence of tempestite in the study area is summarized,and there are four kinds of tempestite sequences and two kinds of tempestite.By analyzing the lateral development of tempestite and related fluid dynamics,the tempestite sedimentation model of the study area is established,so as to better understand the deposition process and sedimentary characteristics of tempestite in the study area.Combined with the previous studies on the factors that may trigger the tempestite deposition,the factors that may trigger the tempestite deposition in the study area are discussed.It is concluded that the development of the tempestite in the study area is affected by many factors,among which the palaeoclimate,palaeogeography and provenance supply are the main factors.The average reservoir porosity of Tenggeer Formation 1 member,Aershan Formation 4member?sand group and the reservoir is 11.4%,9.2%and 6.7%,respectively.The average permeability was 5.4×10-3?m~2,2×10-3?m~2 and 1.31×10-3?m~2,respectively.Storm deposits are widely distributed and directly contact with source rocks(semi-deep lake mudstone).The mudstone can also be used as a cap rock to form a good reservoir-reservoir-cap combination,thus forming a good oil and gas reservoir.Therefore,the identification and interpretation of storm deposits in the study area is of great significance for future petroleum exploration in the study area.