考虑应力敏感的低渗透底水油藏见水时间预测

目前预测低渗透底水油藏油井见水时间没有考虑渗透率应力敏感问题,基于低渗透底水油藏的渗流特征和储集层介质的压力敏感性等特点,推导出了考虑应力敏感等多因素影响的低渗透底水油藏底水突破时间预测公式。分析了应力敏感、启动压力梯度及油水黏度比对底水突破时间的影响。研究表明:应力敏感系数越大,底水突破越早;随着启动压力梯度增加,底水与井底之间的压力差值越大,底水突破的时间提前;油水黏度比越大,油井见水时间越早;油井见水时间随着产量的增加而提前,因此合理地设计生产井产量,可以延长油井无水采油期。

PREDICTION OF THE WATER BREAKTHROUGH TIME FOR THE LOW-PERMEABILITY OIL RESERVOIR CONSIDERING THE STRESS SENSITIVITY

At present,the prediction of the water breakthrough time for the low-permeability bottom-water oil reservoir does not considerate the stress sensitivity,based on the seepage characteristics of the reservoir and characteristics of the stress sensitivity of the reservoir media,the predicting formula of the water breakthrough time was deduced considering the influences of the factors such as the stress sensitivity and so on.And moreover,the influences of the sensitivity,start-up pressure gradient and oil/water viscosity ratio on the time were analyzed.The studies show that the bigger the stress sensitivity coefficient is,the earlier the bottom water breakthrough will be;with the increase of the start-up pressure gradient,the pressure difference between the bottom water and bottom of the well also rises and the breakthrough time is ahead of the time;the larger oil-water viscosity ratio is,the earlier the water breakthrough time will be;the water breakthrough time is ahead of the time with the increase of the well production.So the reasonable design of the well production can prolong the water-free production period of the oil well.