利用Eaton法计算地层孔隙压力的不确定性分析

Evaluation of Uncertainties for Pore-pressure Taking Eaton Method as an Example

鉴于地层孔隙压力不确定性给钻井工程设计与施工带来的诸多困难,提出孔隙压力不确定度的概念,并对其不确定性进行定量表征。以目前应用最为广泛的Eaton法为例,推导了孔隙压力不确定度的理论计算模型,模型考虑了数据测量误差、压实趋势线方程、Eaton指数、上覆岩层压力以及静水压力等因素,并利用中国石化PG地区综合矿场数据进行了算例分析。结果表明,该方法给出了孔隙压力不确定度的范围、影响主因素以及相关因素对不确定度的影响规律,且计算结果与录井钻井液密度、试气实测结果相符,证明提出的孔隙压力不确定性评价方法可行,计算结果真实、可靠。

In view of the difficulties the uncertainty of pore-pressure brought to the drilling engineering design and construction, the concept of pore pressure uncertainty is present, and the calculation model for pore pressure uncertainty is derivated for Eaton method. An example is analyzed using synthesis data fiom PG block in northeast Sichuan region. The method presented here gives the range and main influencing factors of pore presstire uncertainty, and the influence law of related ihctors to uncertainty. The calculated results are in conespondence with actual mud density and the results of gas production test, which proves that the evaluation method of pore pressure uncertainty is feasible, the results has high accuracy and validity.