Research On Numerical Analysis Method Of Fracture Shape Prediction Based On Potential Fracturing

With the continuous development of domestic oil field exploitation,most oil fields have entered the stage of high water cut and low permeability.In order to further strengthen the connectivity between low permeability reservoirs and the connectedness among subsurface sand bodies in Wells,the target Wells are fractured to create sand-filled fractures with high permeability,so as to improve the seepage capacity and oil drainage area of oil and gas wells,and thereby increasing the oil production of oil wells to accelerate the oil output.Dynamic monitoring of the morphological changes of fracturing fractures in fracturing construction project,and then evaluating fracturing the effects and improving the fracturing schemes have strong practical engineering significance.When the fracturing fluid enters the fracture,an obvious low-resistivity zone will be formed at the fracture,which has a large resistivity difference from the remaining oil zone.The Well ground potential measurement method can accurately measure the surface apparent resistivity distribution of the ground under the stimulation of artificial electric field.The comparative analysis and research,on the surface apparent resistivity distribution before and during fracturing construction,can effectively and dynamically predict the shape of the low-resistance zone due to fracture formation,and guide the field operation.That will help to improve the actual effect of fracturing operation,thus improving oil and gas recovery ratio and realizing stable production and tapping potential of oil fields.Researches are emerging between the forward model and numerical simulation of well-ground potential measurement method and optimization design and data analysis of field detection system in this paper,and the main work is as follows:(1)Under the guidance of the basic theory of potentiometric method,the ground potential analysis formula based on the conductive unit method in the case of two-pole power supply is derived.When the fracturing fluid enters the fracture to form a low resistance band,a mathematical model of the ground anomaly potential in a uniform isotropic subsurface semiinfinite space is speculated.(2)The numerical simulation problem of positive evolution based on fracture morphology prediction based on finite element is studied.There is a comparative analysis between the numerical and analytical solution of potential response,which shows that the rationality of the forward modeling by conductive element method.Considering that the survey points around the target well are limited due to the topography and geomorphology of the target well and its slope during the fracturing construction,we verified the correspondence between the abnormal potential and the azimuth of the fracture according to the eccentric potentiometric method.The distribution of ground potential under abnormal morphological cracks is finished by COMSOL multi-physical field coupling numerical simulation software.So the isostatic line change trend of ground potentials has a good correspondence with the fracture shape,and the feasibility of using the potential method to predict the orientation,shape and length of fractures is further confirmed,which lays a theoretical and data foundation for further inversion research.(3)The equipment composition and key parameters of the test system based on the potential method are analyzed,because of the prediction of fracture orientation is achieved in target wells No.1 and No.2 by using the eccentric potential method.What’s more,the field test technology and process are optimized through field tests.In order to collect and process the potential data of the surface measuring points before and during fracturing construction,the prediction of the fracture orientation and length through comparative analysis.Lastly the monitor of the influence of surface potential distribution caused by crack extension changes are possible to further predict the expansion of the fracture network in the underground oil layer during the fracturing process.It is of great significance for improving the fracturing effect,optimizing the fracturing design,guiding the optimization and upgrading of the testing system equipment in the future.