基于水油颗粒碰撞的安全注水压力预测模型研究

Model for the safety pressure prediction of water injection based on the water-oil particle collision

为提高注水作业的安全性,需对安全注水压力进行有效预测。根据剩余油高度分散、局部富集的特点,从宏观流体拟颗粒角度,分析水油颗粒碰撞力对注水压力的影响。建立二维直角坐标系,按照碰撞力方向与X、Y轴的夹角,将碰撞方式分为直线型碰撞和斜线型碰撞,分析不同碰撞方式下的颗粒运动规律;根据颗粒粒径变化评估碰撞力的大小。然后对注水压力预测分析,建立基于碰撞力的安全注水压力预测模型,结合地层破裂压力,研究安全合理的注水压力。最后运用该理论模型对实例进行分析。结果表明:油井某些点注水压力不稳定,几乎与地层破裂压力重合。微观水油颗粒的碰撞力大小和方向与宏观层面不安全注水压力密切相关,碰撞产生的高温聚集到一定程度时,对不安全事件的发生也有重要影响。

The present paper is aimed at establishing and presenting a safety water injection pressure prediction model based on the collision force of water and oil particles so as to improve the safety of the water injection operation.In so doing,from the perspective of the macroscopic fluid pseudo-particles,the paper first of all would like to analyze the influence of the collision force of the water and oil particles on the water injection pressure according to the characteristic features of the residual oil high dispersion and the local enrichment.And,then,we have also managed to establish the 2-D Cartesian coordinate by dividing the collision mode into the modes of the linear collision and declining collision,so as to specify the linear collision in the collision force direction.This may help to analyze the motion regularity of the different collision modes of the particles along the X axis or Y axis or parallel to the 2 said axes,in the oblique collision when the direction of the collision force within each quadrant except the X axis and Y axis and at a certain angle to the said axes X&Y.Additionally,we have also tested and worked out the magnitude of the collision force based on the variation of particle size.And,then,from the viewpoint of temporal and spatial collision evolution process,we have also analyzed and forecast the safety water injection pressure so as to establish a safety water injection pressure prediction model.Besides,we have also confirmed the safe and reasonable water injection pressure by combining the fracture pressures of the formation.And,finally,we have chosen a typical oil-well according to the water injection pressure and the formation fracture pressure parameters of the oil-well,so that the model can be used to predict and analyze its water injection pressure and the formation fracture pressure parameters,so as to bring about the corresponding safety technical measures.Thus,the results of analysis show that the injection pressure at some points of the well isn’t stable,almost coincided with the formation fracture pressure,and unsafe events may occur if the pressure points would be made to stay longer.Therefore,the magnitude and the direction of the collision force of the micro-water oil particles have to be finally confirmed in close relation with the unsafe water injection pressure at the macro level from the micromechanical viewpoint.Thus,the essential causes can be found and determined so as to provide a brand-new perspective for the theory of the safety water injection pressure.