The Characteristics Research On Chang8 Reservoirs Of Yanchang Formation In Zhiluo Oilfield

Zhiluo oilfield is located in Fuxian.Its tectonic location is in the southeast of Shanbei slope,Ordos Basin.In recent years,it constantly make a major breakthrough on petroleum exploration in Chang8,a lot of industrial oil output have been obtained from many oil wells.It illustrates that the lower Yanchang formation has wide exploration potential.This paper is based on predecessors' research in petroleum geology,sedimentary petrology and reservoir geology theory as the instruction and depending on the technology of experimental test,the integrated application of field outcrops,drilling,logging and production performance data,from the perspective of the research of sedimentary facies and sand body distribution,for chang 8 reservoir petrology features,physical properties and pore structure characteristics,Diagenesis and macroscopic heterogeneity was studied and analyzed on the basis of these eventually probes into the main control factors of reservoir performance and the evaluation of reservoir classification.The study area is located in the northwest part of Zhiluo oilfield.Its provenance is mainly from the north-northeast and west – southwest.In the chang 8 sedimentary period,delta facies is developped in the studied area and the main development of the delta is front subfacies.This is the main reservoir in the study area.Chang 8 reservoir's sandstone has low compositional maturity and the textural maturity is higher.The rock type is mainly feldspar sandstone,with rounded edges and shape as a condition is given priority to,it also has better sorting characteristics and its filler content type is mainly iron dolomite and authigenic clay mineral?chlorite,illite,etc.?.Siliceous minerals,pyrite and feldspathic is followed.The grain sizes of main distribution within the scope of the powder sand and fine sand.Intergranular dissolved pore and intragranular dissolved pore is the main research of chang 8 reservoir's pore types.The other types of pore are very few.The constant speed mercury injection test shows that the more closely the relationship between permeability and throat,throat radius,effective throat volume and effective pore volume and effective pore throat ratio affects reservoir physical properties and the main factors of seepage ability.Chang 8 reservoir's porosity is 7.9% on average and the average permeability 0.22 x 10^-3um².Porosity and permeability has a certain relevance.In the long history of diagenetic,reservoir rock has been experienced all kinds of diagenesis of the and densification.Compaction is the most important factor and the sandstone porosity decreased its rock stage common rock up A stage.Delta front underwater distributary channel sand body is the main reservoir sandstone.On the basis of the sedimentation,the late diagenesis on reservoir physical property of sandstone‘s impact is good or bad,which complicate the reservoir performance.On the other hand,a certain thickness of high-quality hydrocarbon source rocks is the guarantee of the high quality reservoirs of oil and gas rich deposit.Considering sedimentation,diagenesis and reservoir property,chang 8 reservoir is evaluated and divided into four classes I,II,III,?.Chang 8¹ reservoir group and 8² oil layer group is given priority to class III.