The Distribution And Prediction Of Volcanic Rocks Reservoir In Huoshiling Formation Of Wangfu Fault Depression,Northeast China

A total reserve of three hundred billion stere of the Xujiaweizi Gas Field in Songliao Basin at the year of 2002,which encourages quantity of oil workers,is a big breakthrough However,with the further exploration of volcanic oil and gas exploration in the southern Songliao Basin,it is found that the stratigraphic division and contrast of the multistage volcanic rocks in the volcanic strata,the identification of the volcano mechanism and the portrayal of the inner curtain,the distribution of the volcanic reservoir and the law of oil and gas accumulation have become the bottleneck of the further breakthrough in the exploration.In order to solve these problems,this paper,starting with the stratigraphic division and contrast,carries out the study of the volcano mechanism in the secondary framework of the eruption period,depicts the volcano mechanism in several aspects,such as the type of the volcano mechanism,the identification method,the distribution law,the eruption mode,the inside feature and the control factors,and then establishes the different types of volcanoes.Corresponding stratigraphic frame model and frequency inversion method are used for reservoir prediction.According to the identification marks of core,logging and seismic characteristics of the stratum interface,the Shiling formation of Wangfu fault depression is divided into 3 eruption cycles and 8 eruption periods,in which the formation of the gyratory is mainly distributed in the Midwest of the fault depression,the distribution of each stage is scattered,the thickness changes violently,and the two volcanic strata are main in the cycle.To be distributed in the middle of the fault depression,the distribution of each stage is concentrated and the thickness is relatively uniform.The sedimentary strata of the two cycle are mainly distributed in the central and western depression of the fault depression,and the Western thick East thinning is over the volcanic strata,and the three layer of the gyratory is widely distributed in the central and western regions of the faulted area.4 types of volcanic mechanism in the study area are summed up under the period of time frame constraints,and according to the calibration of core and logging,6 typical seismic facies characteristics and corresponding mechanism types are summarized.On this basis,the distribution law of the volcanic mechanism of gyratory one and cycle two is depicted.The needle is fine for the thin stratum thickness and the serious interference in the overlying strata of the gyratory three volcano mechanism.In order to explain the phase of the layer,to extract the fine stratigraphic seismic attributes and to optimize the fusion method of sensitive attributes,a comprehensive description of the spreading range of the volcano mechanism has been made.The results show that 11 volcanic mechanisms are developed in the cycle,16 volcanic institutions are developed in the cycle two,and 2 volcanic institutions are developed in the cycle three.Based on the lithology and lithofacies depiction of the single well,4 types of lithofacies models of the shield like overflow type volcano,the single cone volcanic type volcano,the multi cone volcanic type volcano and the fire mountain clastic cone type volcano are established on the basis of the lithology and lithofacies depiction of the single well.It portrays the characteristics of the inside of the volcano.Through the analysis of the volcanic mechanism system,the control factors of the Wangfu fault depression are summarized: the magma property and the eruption mode control the scale and type of the volcano mechanism;the basement fracture controls the distribution boundary of the volcano mechanism,the basement fracture controls the development position of the volcano channel,and the intersection position of the basement fault controls the location of the eruption center of the volcano mechanism;the paleo topography affects the location of the volcano mechanism.The location of the earth's surface is influenced by the ancient topography.Taking the volcano mechanism as the basic formation frame model,the target inversion body is divided into four parts by frequency division inversion method.The low frequency,intermediate frequency and high frequency data are obtained by logging constraint interpolation,seismic spectrum simulation inversion and waveform phased indication inversion,and the geological seismic synthesis of volcanic reservoir is carried out.Prediction results show that the proposed method improves the resolution and accuracy of prediction.According to the above methods,reservoir inversion prediction is carried out on the volcanic reservoir of the fire Shiling formation in Wangfu fault depression.The plane map of the reservoir thickness is extracted with the volcanic eruption cycle as a unit.The predicted reservoir area is divided into 4 types: the I reservoir is the reservoir of high yield,the second kind of reservoir is the reservoir with better reservoir performance and the third type reservoir.For the general reservoir performance,it is necessary to increase production measures to achieve a good industrial gas reservoir effect,a reservoir with a certain potential for development,and type IV reservoirs to be thin layers or non reservoirs.Among them,I and class II reservoirs are mainly distributed in the central part of the volcano mechanism,especially in the middle fault of the central fault depression of Wangfu fault,and the multistage volcanoes are stacked with each other in the longitudinal direction,and the favorable reservoirs are more easily formed.