| The most often used stimulation treatment in oilfield development is hydraulic fracturing, which has great significance on increasing and stabilizing oil production. The level of the research about hydraulic fracturing will directly influence the efficiency in oil and gas production. Hydraulic fracturing is such a complicated stimulation technique that the research about it should consider many factors in order to be more accurate and better guide construction.Nowadays, many P3D models and full-3D models which are related with fracture propagation in hydraulic fracturing have been proposed. Compared with two dimensional models once popularly adopted it has made considerable progress. But the problems remain. That is when the fracture propagation in the height direction can't be neglected, P3D models without considering the fluid flow in the height direction will not be appropriate. Further more, full-3D models are not mature and still in seedtime.Based on the previous research, considering the deficiency in fracture propagation models, the research work achieved in this paper is as follows:(1) Considering many factors'influence on ground stress, 3D stratified ground stress is analyzed in detail and a calculation method is proposed. Accordingly, based on considering the influence of ground stress, the pressure and filtration of fracturing fluid,a calculation formula about the stress field near wellbore is brought forward.(2) The judgement of fracture morphology is an important task before commencing hydraulic fracturing which directly related to stimulation effect. In this paper based on the analysis of fracture-making condition and fracture pressure a method to judge fracture morphology which defined as fuzzy judgement and precise judgement is first proposed. Accordingly, two methods that can be used to judge whether it will cause vertical fracture or horizontal fracture after hydraulic fracturing have been achieved.(3) According to the stress distribution in cover and bottom, divided as two cases: one is uniform stress and symmetric distribution, the other is uniform stress and asymmetric distribution, a P3D fracture propagation model considering fracturing fluid's one dimensional flow and its numerical solution method is discussed in detail. And the three-dimensional geometry size and the relation between fracture propagation and pump time have been achieved.(4) Considering stress symmetrical distribution a P3D fracture propagation model which involves fracturing fluid's two dimensional flow is established.And also the detailed numerical solution process of the model is put forward. And also the three-dimensional geometry size and the pump time which is needed to achieve the prearranged fracture length have been obtained.(5) By using visual basic language and fortran language an engineering applied software has been compiled. By utilizing the software, the analysis and calculation about the stratified ground stress and stress field nearby wellbore, hydraulic fracture morphology judgement, fracture P3D propagation and other problems related with hydraulic fracturing has been realized.
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