Characteristics And Prediction Of Yan'an Formation Yan 8 Yan 9 Oil And Gas Reservoirs In Pengyang Area

Pengyang area is located in Tianhuan Syncline,a secondary structural unit in Ordos Basin.At the end of Triassic,the Indosinian movement led to serious denudation of Yanchang Formation,and the strata below Chang 6 were missing locally;In the early Yan 'an period,it was also affected by the high ground of military exercises,and the stratigraphic distribution changed greatly.Some of them did not accept Fuxian and Yan 10 and Yan 9 deposits,and the stratification was not uniform;At the same time,the development of low-amplitude structures,such as faulted anticline and faulted nose,and the complexity of structural characteristics,all contribute to unclear reservoir control factors.Therefore,previous studies on Jurassic sedimentary facies and reservoir formation in this area need to be further deepened.To solve the above problems,firstly,this paper has completed the basic work of stratigraphic division and correlation under the guidance of sedimentology,structural geology and hydrocarbon accumulation theory.The main structural features that cause oil and gas control factors in the study area are analyzed.Combined with seismic profile interpretation,the local structural or fault features and their influence on reservoirs in the study area are analyzed.Secondly,according to the distinguishing marks of sedimentary facies,one sedimentary facies and four sedimentary microfacies are divided into the target horizon.On the basis of single well sedimentary facies analysis,the sedimentary facies of connected wells are analyzed,and the sedimentary facies plan and sand body thickness map are drawn.By comparison,it is concluded that the deposits of Yan 8and Yan 9 have good inheritance.Then the petrological characteristics,pore structure and porosity and permeability of the reservoir are analyzed.On this basis,combined with electron microscope and cathodoluminescence analysis,the diagenesis types can be distinguished.That is,it includes compaction,cementation,metasomatism and dissolution,so as to analyze the influence on reservoir evolution.At the same time,it is further determined that the diagenetic stage of the target horizon belongs to the middle diagenetic A stage.Finally,referring to the gravity inversion results,the dessert area is roughly delineated.Then,through two-dimensional seismic data processing,attribute analysis is carried out.As well as well-seismic calibration,well-seismic joint inversion and other links,finally constrained the inversion results together,delineated four favorable areas,and completed reservoir prediction,which provided an important reference for further exploration work in the study area.