Establishment And Application Of A Fracture Network Model Based On Fractal System

The micro-seismic monitoring shows that the multi-stage hydraulic fracturing technique can generate a complex fracturing network in the near-well area and improve the well production.The current fracture modeling method is still lacking for the multi-level and bifurcation characteristics of the complex fracture network.In this paper,a fractal network model is established based on L-system of fractal geometry system.The model not only has the characterization ability of complex fractures,but also follows the control rules of fractal geometry propagation.The analysis shows that the complexity of fractures network and the properties of the secondary fractures also have a great effect on the decline rate of the production curve,the lower fracture network complexity(or connectivity)or secondary fracture conductivity will lead to a rapid decline rate.Therefore,the simple linear orthogonal fracture assumption cannot fully reflect the flow characteristics of the fracture network.Then,based on the fractal fracture network,the fracture geometry matching and the attribute inversion workflow is established under the constraint of micro-seismic events and historical production.Firstly,the optimal fractal control parameters which can match the microseismic events’(MSE)constraint are determined by integer programming method,then the application of rate transient analysis(RTA)method and history matching theory is to help modify the morphological parameters and fracture conductivity.The workflow also provides a direct application of intelligent optimization algorithms such as genetic algorithm to carry out a fast conductivity matching.The fractal geometry system can guarantee the fast independent solution of the fracture properties at all levels,and the results of the two methods both have high fitting on the actual production.Finally,this paper extends the application of the fractal network model:(1)The multi-leveled feature of the fractal geometry is a powerful tool for the fracture network calibration.The model automatically classifies the fracture network after geometry matching and it is used for the simple estimation of the main fracture area,then,with the results of RTA,the contributing reservoir area is accurately calibrated.(2)By iterating the generating rules,the final geometry of the fractal fracture is obtained,this mentions the adjustability of the geometry and the properties of the fractal fracture network and make it more efficient to simulate the performance of the refracturing.(3)Fractal fracture network model and mine large data analysis method has a very high degree of fit.As a fractal system,of which the geometry is controlled by the fractal parameters,it helps to quantify the fracturing construction and geological parameters and connect with the mainstream machine learning algorithms.: Applying decision tree system(or other classification algorithms)to classify the fractal parameters after matching the MSE is a new way to deep analyze and evaluate the fracturing performance;The correlation analysis between the construction and geological parameters and the fractal matching parameters by constructing an artificial neural network provides a new mode for the prediction of the complex fracture network.