Research On The Stress Distribution And Sanding Prediction Model For Horizontal Wells

Unstressed sand reservoir is distributed widely, and sanding is a seriously problem of this reservoir. Horizontal well is an important way to develop the unstressed sand reservoir, so it is important to predict the condition of sanding in horizontal wells. However, at present, there isn't a general research on this issue.This paper analyzed the character the wellbore trajectory of the horizontal well because of the sanding of unstressed sand reservoir. With the help of rock mechanics and the stress model, this paper improved the model for predicting the stress distribution. On the basic of stress distribution in immediate vicinity of wellbore, the author raised the conception of sanding characteristic radius. Using this conception and the rock failure rules, the author built the horizontal well critical sanding pressure drawdown model. Further, this paper presented a model about predicting the stress distribution around the horizontal wells and the sanding radius, on the basic of elastoplasticity theory and the model about the stress distribution in elastic range around the horizontal well.According to the mentioned model, the author developed a self-contained horizontal well sanding prediction software to calculate and analyze the model. By the analysis of the stress, sanding critical drawdown, sanding radius, it was found that they are obviously influenced by the hole deviation angle and drift azimuth. In the same area, the tilt rate of the horizontal well and the select of the horizontal section would influence the sanding degree obviously. Meanwhile, the critical drawdown of the horizontal wells is greatly related to the oil production, rock mechanics parameters and the characteristic radius. At the same time, the history of the stress around the horizontal wells, sanding critical drawdown and sanding radius along the wellbore trajectory was studied, and it showed that along the wellbore trajectory sanding in different section is different. In short, as to the sandcontrol of horizontal well, we can take measures to control the seriously sanding sections at first.At the end of this paper, the author employed the finite element simulation software to certification the result of horizontal well sanding prediction software. The results show that the horizontal well sanding prediction software is feasible.