Study On Reservoir Geological Modeling Of Yan10in Zhen250District Of Zhenyuan Oilfield

The Jurassic reservoir in Zhen250district of Zhenyuan Oilfiedl, represented by Yan10oil formation, belongs to fluvial facies reservoir with good physical properties but rapid lateral variation and strong reservoir heterogeneity. Zhen250district has been put into exploitation since2009, of which the major reservoir layer is Yan102sublayer, however, due to its short history of exploitation, the study of Jurassic reservoir is not enough. Moreover, some problems have emerged during the process of exploitation. Therefore, it is urgent to carry out a systematic study and recognition of the Yan10oil formation in Zhen250District and of the policies in fine exploitation technologies, and this is very important for later exploitation regulation of the oilfield and the development of ultimate recovery ratio.The present study takes the Yan10oil formation of the Jurassic reservoir in Zhen250District of Zhenyuan Oilfield, Ordos Basin as its subject, obtained geological information,well log information,core analysis infoamation,production performance information,formation test information and result of fine description by comprehensively applying oil field geology,well drilling,well log,reservoir test,exploit production and a variety of channels.Using development geology,geostatistics,modem reservoir engineering theory,oil and gas accumulation numerical simulation as a guide, accomplished all the research work by the prerequisite of comprehensive research and well-designed.On the basis of a fine reservoir description, stratigraphic classifications and comparisons will be made. With reference the regional sedimentary background, sedimentary microfacies research will be studied through establishing standard microfacies bar chart, electrofacies, single well facies, etc. Based on the interpretation of the results of the second fine logging, the macro distribution of the reservoir will be analyzed, and the influence of the reservoir heterogeneity and the distribution of sedimentary microfacies on the distribution of oil will be studied.Finally a static three-dimensional geological model describing the structure, reservoir and the spatial distribution of fluid will be builted, and it will quantitatively present the characteristics of the distribution of the Yan10reservoir at a three-dimensional level in Zhen250District, and also, it will lay a very good foundation for designation oil formation numerical simulation and later studies of reservoir engineering. The major findings achieved in the present study are as follows.1. Based on the fine stratigraphic classification and comparison, and according to the principle of "cyclic correlation and step control",, By repeating comparative study of the region through the lithologic character,electric property,cycle of sedimentation and united identical elevation and thickness under the control of marker bed, establish eight skeleton correlation profile and so accomplish united closure of the whole district. The major layer of Yan10is divided into three sublayers, i.e. Yan101, Yan102, Yan103. From chart of the cross-sectional comparison of the sand body in this region, we can see that the stratigraphic thickness in the region is relatively stable and it varies at a small level, and the stratigraphic position is also stable, and the electrical properties shown in the marker bed are distinct. The average thickness of Yan102and Yan103is a little thick, and that of the Yan101is a little thin, and this is related to the sedimentary environment in this region. On the basis of the well point data and the geological trend, the present study has built a tectonic model through cross-hole kriging interpolation.2. Based on the characteristics of core and log curve, and by referring to the regional sedimentary background and previous studies, we can determine that in this area the sediments during Yan10are mainly from the northeast, and the study area belongs to fluvial facies sedimentation, which can be subdivided into three kinds of sedimentary microfacies, i.e. channel deposit,channel lateral margin and flood plain, with the microfacies of channel as the main reservoir sand body. Sing well facies analysis was conducted to eight wells, and profile analysis was conducted to four sections, and by comparing results of those analyses with the characteristics of plane distribution of sand body, we can determine the distribution of sedimentary microfacies in this area.3. Reservoir of Yan10is chondro-mesograin feldspar lithic sandstone with low porosity and medium permeability for the whole.The heterogeneity of the reservoir was studied from three aspects:in-layer heterogeneity, interlayer heterogeneity and plane heterogeneity.In-layer heterogeneity concerns the distribution rhythmicity of vertical grain size,intraformational bed and degree of permeability heterogeneity,we can conclude that Yan102has weak in-layer heterogeneity,but Yan101and Yan103have medium in-layer heterogeneity;Interlayer heterogeneity mainly include the longitudinal distribution of the reservoir, the heterogeneity of interlamination permeability, and characteristics of the distribution of barrier bed between layers, etc,concluding that Yan101has strong heterogeneity,Yan102and Yan103have medium-strong heterogeneity. Plane heterogeneity is mainly concerned with the continuity and the connectivity of sand body, and the variation of the physical properties on the plane of the reservoir, to be specific, the present research has studied the characteristics of the variation in the reservoir’s porosity and permeability on the plane during three sedimentary periods i.e. Yan101, Yan102, Yan103.4. The geological model of the reservoir in Zhen250district was built on the basis of the materials in geology and logging and by using the pixel-based Sequential Indicator Simulation in the software of Petrel to simulate sedimentary microfacies and lithofacies, and also by using Sequential Gauss Simulation in the technology of facies-control to simulate the physical parameters. And the model established in the present study is a quantitative3-dimensional geological model. Also, an evaluation of different models was made in order to select an optimal model of sedimentary microfacies and also an optimal model of physical parameters. Finally through the comparison between simulation parameters and the original input data, the comparison between the lithofacies model and the section of porosity model, the comparison between the geological model of the reservoir and the manual plotting of the plane distribution, and reserve fitting, etc. the results gained from the geological model of the reservoir built in the present study were analysed.