Sedimentary Characteristics And Prediction For Favorable Reservoirs Of Deepwater Deposits In Group 1 At Tengger Formation Of Aer Sag

Aer Sag is a small halfgraben-like basin with faulting in the northeast of Erlian Basin.Previous studies have shown that there are deepwater depositts such as mudstone and gravity flow sandstone in Aer Sag.But their petrologic feature,physical characteristics,distribution,and reservoir prediction are lacking adequate research.This paper aims to answer these questions and provide a scientific basis for predicting favorable reservoirs through the core data,well logging,seismic,combining with related experimental analysis.First,through the stratigraphic interface identification of 3d seismic and logging data,using classical sequence stratigraphy theory,this paper divides Group 1 of Tengger Formation into three sedimentary sequences(SQ1,SQ2,SQ3)and nine system tracts.Through single well and connecting-well analysis,mudstone thickness and seismic amplitude attribute analysis,this paper finish sedimentary facie maps of nine system tracts,and make it clear that deepwater mudstone mostly distribute in SQ1,gravity flow sandstone mostly distribute in sublacustrine fan of SQ2 and SQ3.Second,base on the results of XRD,geochemical experiment,nitrogen adsorption,and so on,the main mineral of mudstone is illite mixed with smectite.The average TOC is close to 2%.Most kerogen is type?,and Ro is close to 0.6%.The lamellar mudstone with high organic matter is the best reservoir.The reservoir space is mostly microfracture and organic pore,and the pores are mainly mid-level pore.Third,through experimental means such as core and slice observation,particle size analysis,sandstone is divided into 4 kinds of lithofacies,and the main minerals are quartz and feldspar,matrix is more than 15%.According to the Sahu formula,gravity flow sandstone and delta sandstone are distinguished,and they both can be good reservoir.The average porosity of sandstone samples in this area is 9.2%,and the average permeability is 81.6mD.Reservoir space is dominated by intergranular pores,and the pore size is mostly dozens of micron.According to physical characteristics and main control factor analysis of deepwater mudstone and sandstone,this paper make it clear that where the good reservoir locates in different system tracts.Results show that the good mudstone reservoir may locate in the northern part of AE13 in SQ1 and the good sandstone reservoir locate nearby AE3,AE13 and AE1 in SQ3.