Zhao Wanchun

The Study Fracture Evolution of Coal and Rock Mass Under Hydraulic Fracturing

The hydraulic fracturing technology is the main technical means of coalbed methane. However, it is hard to describe the fracture formation mechanism and evolution law in the process of fracturing. It caused the present studies restrict the effective mining of coalbed methane. This article is mainly study the process of fracture cracking and extending based on the angle of energy. It introduces the theory of entropy to analyse the micro defect evolution under hydraulic fracturing, and builds up the evolution model of the micro fracture number, angle, length and opening based on the theory of entropy. Then it analyses the main controlling factors of the fracture evolution. It will provide a new research approach for the law of hydraulic fracturing evolution. Key words: Entropy theory; Hydraulic fracturing; Damage evolution

The Study of Fracturing Rock Body Damage and Cracks Propagation Model Basing on Catastrophe Theory

It is vital for the study of fracturing parameters optimal design and fluids rate forecast to calculate fracture propagation parameters accurately. In order to calculate fracture propagation accurately, in this paper, the model for calculating the value of energy release when the rock body collapses was established basing on catastrophe theory, considering that the collapse of fracturing rock body was caused by the accumulation of rock body deformation energy and releasing suddenly. And making the assumption that the energy that had released can be used for the propagation and extension of the cracks, the new model for calculating the parameters of cracks were established. The characteristics of sandstone rock mass were selected to study and analyze the fracturing parameters through laboratory experiment in daqing oilfield, the results show the maximum error between theoretical and the actual result is 9.71%. The new method that was put forward this paper has important academic value to study fracturing propagation.

The Study and Application of Gray-Orthogonal Wavelet Network Forecasting Mode on Cementing Quality

The interrelated characteristics and the complexity of cementation quality affecting factors are considered, a new method of forecasting cementing quality based on Gray-Orthogonal wavelet network is set up. The method regards some factors affecting the cementing quality as the input parameters of the model, and regards quantifying cementation quality as the output parameter of the model. Evaluating and forecasting the cementing quality of Bei1 block of 20 wells in Daqing Oilfield. The maximum fractional error between forecasting results and actual results is 2.66%. The associated problem of impacting factors is solved by the new forecasting method，and the prediction accuracy of cementing quality is improved. A reliable theoretical basis of cementing operation parameters design and construction program adjustment for new wells in oil field is provided. Key words : Cement job quality; Gray system; Orthogonal wavelet neural network

The Study of Rock Body Damage Constitutive Model in Multiple Fracturing

In order to characterize the mechanical behavior of rock body damage evaluation and forming multiple fractures, in this paper in multiple fracturing, we have established rock body damage evaluation constitutive model, and given the point that the rock can bear secondary damage in multiple fracturing. Established the secondary damage evaluation model, and obtained the method for calculating the parameter of the crack in multiple fracturing. We have verified the model by an oil well in Jilin oilfield, the result has fitted well with the actual engineering. Key words : Multiple fracturing; Damage evaluation; Secondary damage

Fold Catastrophe Model of Fracture Propagation of Hydraulic Fracturing

According to energy conservation from the destruction of rock catastrophe, a new calculation method of the length of fracture propagation in hydraulic fracturing is proposed, and assuming the crack extends to approximate ellipse, the width calculation model of fracture extension is established. By using this new method in Changsheng well of Jilin oilfield, And the maximum error between the productivity that calculated by using the new method and the actual oil production is anastomosing. the method is an innovation in parameter calculation of crack propagation with the destruction of rock catastrophe, and it supposes some new theoretical foundation for the design of fracture parameter optimization. Key words : Hydraulic fracture; Fold catastrophe; Fracture parameters

Notice of Retraction A Research on Statistical Analysis Methods of Factors Influencing Cementing Quality in Daqing Oilfield

In order to enhance cementing quality statistics Analysis Methods of Factors Influencing Cementing Quality, basing on limitations of the two methods analyzed, the nine factors were chosen, formation pressure coefficient, permeability, borehole enlargement rate, diameter rule degrees, drilling fluid density, drilling fluid viscosity, slurry density, casing center degree, displacing return velocity. which provides theoretical basis of the parameter adjustment of factors in the cementing operation .the application of new method in Daqing oil field, the result is well fitted.