基于多变量概率模型的钻井周期预测方法

Predictability of well construction time with multivariate probabilistic approach

鉴于现有的预测钻井周期的方法忽视了影响钻井周期的关键因素因而精确度有限,提出采用多变量概率法预测钻井周期,并采用实测数据进行了算例分析和验证。利用自适应核密度估计法建立了各主要钻井阶段与深度相关的钻井周期概率模型,结合蒙特卡洛模拟得出了一次完整钻井施工作业的总周期的概率分布。采用该方法对澳大利亚及亚洲地区192口井的钻井周期进行了预测。尽管现有数据记录不全,但经过统计分析发现,模型模拟结果与实测数据的匹配度很高。研究表明,在10%~90%的置信区间内,总钻井周期比无事故钻井周期延长至少4 d,至多12 d。采用该方法可以得到钻至一定深度的可能的施工周期,有利于评价整个钻井施工过程的风险,模拟数据还可以用于机器学习模型的训练。图10表2参34。

Current univariate approach to predict the probability of well construction time has limited accuracy due to the fact that it ignores key factors affecting the time.In this study,we propose a multivariate probabilistic approach to predict the risks of well construction time.It takes advantage of an extended multi-dimensional Bernacchia-Pigolotti kernel density estimation technique and combines probability distributions by means of Monte-Carlo simulations to establish a depth-dependent probabilistic model.This method is applied to predict the durations of drilling phases of 192 wells,most of which are located in the Australia-Asia region.Despite the challenge of gappy records,our model shows an excellent statistical agreement with the observed data.Our results suggested that the total time is longer than the trouble-free time by at least 4 days,and at most 12 days within the 10%-90% confidence interval.This model allows us to derive the likelihoods of duration for each phase at a certain depth and to generate inputs for training data-driven models,facilitating evaluation of the risks of an entire drilling operation and has a potential to be used to generate input for data-driven model.