【摘要】 钻井过程中,准确了解钻头前方地层压力的变化对于制定合理的钻井措施、保证钻井安全十分重要。但现有钻前地层预测方法均存在不足,预测精度难以达到现场施工的要求。通过分析地震层速度与地层压力的关系,改进了利用地震层速度预测钻头前方地层压力的Fillippone法,介绍了改进的Fillippone法中岩石骨架速度和修正参数的确定方法。改进的Fillippone法以区块地质信息和已钻井数据为依据进行模型参数初始化,结合随钻获取的有关地层压力数据及钻井液密度信息对预测模型参数进行实时更新,可提高钻头前方地层压力预测的准确性。该方法在新疆准噶尔盆地多口井进行了试验应用,结果表明,其地层压力预测值相对误差小于10%,与传统的趋势线方法和Fillippone法预测结果相比,预测精度明显提高。应用结果也说明,改进的Fillippone法科学有效,能够满足现场施工的安全和技术要求。更多还原

【Abstract】 Pore pressure prediction ahead of bit is very important for selecting reasonable drilling measures and ensuring drilling safety in the well drilling process.However,the existing methods for formation prediction ahead of bit all have shortcomings,making it difficult to achieve prediction accuracy required for field operation.Through analysis of the relation between seismic interval velocity and pore pressure,a modified Fillippone pore pressure prediction method ahead of bit with seismic interval velocity was proposed,and the determination methods for rock matrix velocity vmax and correction parameter n were also presented.Firstly,the parameters in the model were initialized according to the region geological information and the data of drilled well.Then the acquired pore pressure data and drilling fluid density data while drilling were incorporated into the model as the constraint and made it possible to update the parameters in the model in real time.Thereby,pore pressure prediction accuracy was improved.The proposed method has been applied to certain wells in Junggar Basin in Xinjiang Oilfield and the relative error of pore pressure prediction was less than 10%.Compared with the traditional methods such as trend line method and Fillippone method,this method was much higher in prediction accuracy.In addition,field application showed the method to be scientific and effective,and could meet the needs of safety and technical requirements.更多还原