Sedimentary Characteristics Of Tight Oil Reservoir And Prediction Of Favorable Exploration Targets,Anan Sag

A'nan sag is located in the Inner Mongolia Autonomous District Central Xilin Gol Grassland,the tectonic location is located in Erlian Basin MANITE depression in the East,which is a prospective area of the Huabei oilfield.In the lower Et1 in the Anan Sag,Erlian Basin,lake and delta facies deposited and rocks mainly include tuff,carbonate,mudstone and fine-grained clastics rock.In this kind of reservoir,properties and oiliness of different reservoir sand body vary obviously,owing to different reservoir sedimentary environment.this kind of reservoir is scattered in the plane,which isn't typical contiguous.Therefore,Whether it belongs to the dense oil reservoir still remains to be explored.The target layer is the lower Et1(four level sequences),which can be divided into 6 sequences.Establishing a high-resolution sequence stratigraphy framework is basic for our research.Using 76 wells data,combined with core observation,thin section identification and geophysical technology,we do the research on this kind of reservoir's reservoir sedimentary characteristics and favorable exploration facies distribution in Anan sag.Some of the following points are obtained in the study:1.River Delta and sublacustrine fan deposited,forming the “Tight oil reservoir”which mainly derived from the source to North and northeast area.Special lithology,a total of two sources,a is a type of airborne formation tuff,the other one is water carried tuff.The latter favorable reservoir is formed through the transformation of the flow.2.Tight oil reservoirs are developed in different sequences,favorable reservoir growth sublacustrine fan deposits and fan body of different period stack.Favorable reservoir which is scattered in the lake facies is in multi superimposed sublacustrine fan reservoir sand body.3.The petroleum which is detected in AM2 well are mainly in the clastics rock in S1 period which grow traction current deposits in the slope of the basin.This special reservoir which grow gravity flow deposits is found in AM2 well in S2 and S3 period.This kind of reservoir also is found in A27 well in S4 period,being detected in A47 well in S5 period.4.A number of favorable zones are proposed by the analysis of the seismic attributes and the prediction of sedimentary and sequence.Among them,2 favorable zones in S1 period,S2 period 5 favorable zones,5 favorable zones in S3 period,7favorable zones in S4 period,7 favorable zones in S5 period.