Study On Long-term Conductivity Of Fractured Fractures In Tight Sandstone

The development of He-1 reservoir of Daniudi Gas Field which has a large reserve has a significant economic potential when hydraulic fractured.But in the production process,the single well shows the characteristics of rapid decline in output.Varieties of practice and analysis indicate that fractures are closed to different extents related to different particle sizes(middle sand and fine sand)and different rock mechanics of reservoirs,that is,conductivity decreases.Therefore,it's an important step to realize the efficient development of He-1 reservoir by optimizing the fracturing design scheme based on evaluating the long-term conductivity of fractures.A long-term conductivity indoor experiment is carried out with the outcrop rock of He-1 stratum located in Daniudi Gas Field of Ordos Basin.The experiment respectively analyzes the impact of sand concentration,type and size of proppant and reservoir rock mechanical parameters on the long-term conductivity of hydraulic fracture.Rresults show that the effect of closing pressure of long time,the deformation,embedding and broken of proppant,the fracture width decreases,which are the main causes for conductivity's decline by 80% at highest at the end of the experiment.According to the analysis above,the elastic force theory is used to analyze the microstructures of the proppant particles,and a calculation model of the conductivity is established.The contributory factors of the conductivity were evaluated from the standpoint of the proppant and the reservoir.Based on laboratorial and numerical evaluation,productivity of single fractured well under variable conductivity are optimized by means of numerical simulation,and also fracturing parameters by orthogonalization method.