Identifying And Modeling Research On Structural Fractures Of Chang6 Formation In Yuancheng Area,Ordos Basin

Because of new theories and new technology,great breakthroughs of the global unconventional oil and gas exploration and development continue to be obtained.The unconventional oil and gas has become an important part of the global oil and gas resouces.As a kind of unconventional oil and gas resources,the tight sandstone oil and gas reservoir plays a very important role in oil and gas exploration and development.Fractures are developed commonly in tight sandstone reservoirs and have an important influence on the exploration and development.However,it is difficult to obtain detailed and accurate information under the current technical conditions,and the complexity of the fracture itself leads to the difficult condition of the research.In order to improve the recognition of the law of the fractures' distribution and the law of fluid seepage in related reservoirs,it is important to provide the objective basis for the deployment and development of oilfields,and to carry out accurate description and prediction of fractures.The current results of production and scientific researches show that the characterization and prediction of fractures need to adopt a multi-disciplinary and multi-method collaborative approach,so as to achieve the purpose of improving the success rate during the process of exploration and development.Based on the previous researches,this article takes the Chang 6 oil layer of the Triassic Yanchang Formation in the Yanchang Area of Ordos Basin as the research object.Combined with the analysis of well acoustoelectric imaging logging and different paraments(occurrence,density,opening degree,porosity,etc.)based on the investigation of field outcrops and the observation of drilling cores,the qualitative and quantitative description can be obtained.The development and distribution of structural fractures can also be analyzed at the same time.Then the relatively reliable discrete network fracture model can be established on the basis of the deterministic modeling and stochastic modeling and the attribute model of the fracture(porosity model and permeability model)will be got via calculating.The stochastic modeling about structural fractures of the target formation can clearly simulate the distribution characteristics of the underground fractures in the three-dimensional space,and then,the related porosity can be calculated on the basis of the fractured geometrical model.The results which match well with results of the outcrop survey,core observation and imaging logging show the accuracy of the fracture model.Meanwhile,the results show that the effect of the fracture on the porosity of the reservoir is limited regarding the sandstone reservoir in research,and the main contribution of the fractures is to improve the reservoir permeability.