Research On Rule Of Rock Damage And Permeability By Well Explosion

In the trend of petroleum exploitation, the position of low permeability reservoir has been rising. The exploitation of low permeability reservoir has become the global megatrends. Explosive fracturing is an potentially method in developing low permeability reservoir, and it effect the rock around the borehole with a complex process. The current experiment of explosive fracturing is still absent, so the laboratory experiment of explosive fracturing is studied in this thesis.The simulation test device of explosive fracturing is developed in this thesis, to research the rule of cement sample damage by blast wave and explosion gas. According to the experimental device the program is designed, to study the effect of explosive fracturing and the damage of cement sample by different explosive quantity, confining pressure and materials.On the base of explosive fracturing experiment, scattergram of macro-cracks is obtained and then distribution characteristics and rules of the sample surface cracks by fractal theory. The results of the study show that: the surface cracks of cement sample process fractal characteristics, and the fractal dimension can describe the damage of the sample as a parameter during explosive loading. As the explosive quantity increase and the confining pressure decrease, the fractal dimension of cracks increases linearly.Based on relative damage, fracture porosity and permeability, the quantitative evaluation method for the cement sample after exploding is established. The elastic wave velocity of core before and after explosion is measured, and the elastic parameter of sample is calculated; The fracture porosity of sample after explosion is gained; The permeability of core before and after explosion is measure. The variation of relative damage, porosity and permeability with explosive quantity and confining pressure is deduced. The relative damage model of cement sample after exploding is established, the quantitative relationship between relative damage and permeability is deduced under experiment condition.Based the feature of that crack number is more, crack length is shorter and the permeability around the borehole is different, the dynamic production forecasting formulas of explosion fracturing well is deduced in this thesis. According to the above analysis result, the dynamic production forecasting software of fracturing well is designed. On that basis, it is studied that the production of well was influenced by the number of cracks and the length of crack.