The Prediction Of Relatively Prolific Reservoir Of Chang 7 Reservoir Of Yanchang Formation Of An 83 Well Area In Ordos Basin

Low permeability reservoir has a significantly important position in our country. It is a common problem faced by domestic and foreign that how to explore and develop low permeability reservoir with reasonable and effective method. For the further study of low permeability reservoir, we had found that the relatively prolific reservoir which has a relatively high porosity and permeability intervals under low porosity and permeability development background in general. The oil and gas resources of low permeability reservoir are mainly concentrated in these relatively high-quality reservoir. Therefore, it is a very important significance for us to find the relatively prolific reservoir which has a relatively high porosity and permeability under low porosity and permeability development background generally. It is helpful to improve the success rate of exploration and development and production.In this paper, we regard the Chang 7 reservoir of An 83 area in Jiyuan oilfield in Ordos Basin as a typical low permeability reservoir to analyze the relatively prolific reservoir. Starting with core description and integrating with the data of previous research, regional geological setting, core analysis and logging data by means of rock thin section, cast section, SEM, cathodology, mercury penetration curves,through the combination of theory and practice,the macrostructure and microstructure research methods. We summarizes the basic geological characteristics of An 83 area in Jiyuan oilfield based on the integrated analysis of depositional features with the theories of petroleum geology,sedimentary petrology, reservoir geology, logging geology,and geological statistics,which including the characteristics of deposition systems and reservoir characteristics. The research indicated that the study area belongs to delta front deposition,and the reservoir sandstone is mainly composed of the underwater distributary channel,where subsea distributary channel flank and subsea natural barrier are next. The type of rock is mainly composed of feldspathic sandstone. Reservoir space of reservoir sand bodies of intergranular pore and feldspar dissolved pore.The average porosity of The Chang 7 reservoir of An 83 area is 8.85% and the permeability is 0.20 mD, with a typical low permeability special low permeability reservoir characteristics.The oilfield exploration and related research show that there are many factors affect the reservoir capacity and sums up can be divided into two categories, which one calls reservoir factors, the another kind calls a reservoir factors. According to the formation data and Testing and Production Test Data of the Chang 7 reservoir of An 83 area in Jiyuan oilfield in Ordos Basin,we analyze the factors affecting the reservoir capacity in the study area and to determine the main factors which affect capacity. By analyzing the main factors affecting the production capacity,we have established a relatively prolific reservoir prediction model. In order to make the more objective,through analysis a variety of methods to determine the weighting coefficients of the relatively prolific reservoir prediction model,finally we choice the analytic hierarchy process to establish a more objective relatively prolific reservoir prediction model.Based on the detailed geological data of the Chang 7 reservoir of An 83 area,we use Petrel software, stochastic modeling approach and the principle of phase control modeling to establish a geological model which can be well described structure, reservoir, fluid spatial distribution, which including porosity model,permeability model and saturation model.By verifying the model accord with the geological conditions, the geological model which is objective,authentic accurately reflect the underground geological conditions,which has a high reliability.When the three-dimensional geological model was built,the relatively prolific reservoir prediction model be applied to it.We can clearly know the regions of relatively prolific reservoir, which is the High-Quality Reservoir under low porosity and permeability development background generally.This research provides a references basis how to determine the High-Quality Reservoir which is similar to ultra-low permeability and low permeability like the Chang 7 reservoir of An 83 area. As a basis for the guidance of high-yield rich region identification,evaluation and selection, it also can provide a reference for the ultra-low permeability and low permeability reservoir development in domestic.The subject of comprehensive evaluation of low porosity and low permeability reservoir is one of the frontier topics in the field of petroleum and gas in today. In this paper,the combination of the prediction model of the relatively high yield and enrichment region of the low porosity and permeability reservoir and three-dimensional geological model will undoubtedly enrich and improve the theory and application of ultra-low permeability and low permeability,which is of great significance to similar reservoir exploration and development.