Study Of Effective Supporting And Conductivity Prediction Model For Channel Fracture

The channel fracturing technology forms a high-speed channel network supported by the supporting columns in the fracture,which increases the artificial fracture conductivity by several orders of magnitude.Effective support is the key to maintain the high conductivity of fractures.It is mainly affected by the deformation and embedding of support columns.However,little research has been done on this part at present,leading to large errors in the prediction of channel fracture conductivity.This dissertation studies the closure law of channel fracturing cracks through the theoretical model.Based on this,it studies the fracture conductivity of channel fracturing through theory and experiment.The support pillar in the channel fracturing crack is the core part of the crack.In the results of large-scale visualized flat plate experiment,cylindrical and elliptic cylindrical support column models are extracted.The self-developed channel fracturing support column mechanical parameter testing device The mechanical parameters of the support column were tested to obtain the nonlinear constitutive relation of the channel fracturing fracture support column.The influence factors of the mechanical properties of the support column were experimentally analyzed.The results showed that the higher the density,the lower the ratio of height to diameter,the greater the roundness.The smaller the support column deformation,the nonlinear constitutive model is used to characterize the constitutive relation of the support column based on the geotechnical theory.By using the Boussinesq and Cerruti potential functions and the basic model of the normal concentrated force of the elastic half-space body,the deformation and stress distribution of the formation under different shape of the force region are obtained.Then the channel fracturing fracture supporting column embedded model is established based on the contact theory.Combining the constitutive model of the supporting column,taking into account the deformation and embedding of the supporting column,a calculation model for the width of the fracture of the channel fracture is established according to the superposition principle.The model can accurately calculate the slit width at each point and obtain the slot width distribution matrix in the pillar-type crack.At the same time,based on this model,the study of the factors affecting the width distribution of the slits shows that the factors affecting the width distribution of the cracks in the channel are very complicated.Based on the calculation model of the channel pressure crack width,the pillar-type fracture geometry model and physical model are first established.The channel flow part and the porous medium flow part in the fracture are considered.The coupling channel flow model and the porous medium flow model are constructed based on the LBM method.A fracture cross-scale flow model,combined with a pillar-type fracture physical model,establishes a prediction model for channel fracture fracture conductivity,and analyzes the influencing factors of channel fracturing fracture conductivity at an engineering scale.The results show that the closure pressure is smaller.The greater the elastic modulus of the reservoir and the higher the ovality of the support column,the higher the fracture conductivity.The concept of effective supportability of pillar-type cracks was proposed,and experimental verification was carried out.A new method for channel applicability evaluation and parameter optimization was proposed.Through this method,a well in Shengli Oilfield was field-applied and the construction parameters were optimized.,Comparing the production before and after fracturing,achieved a better effect of increasing production.In this paper,based on the definition of the pillar-type crack closure law and the influencing factors of the conductivity,a new assessment method for channel fracturing applicability and a parameter optimization design method are proposed,which lays a foundation for further research on channel fracturing.It has certain theoretical guiding significance for the on-site construction parameter formulation.