基于局部耦合马尔科夫链模型的钻孔优化方法

Borehole optimization method utilizing local coupled Markov chain model

如何合理利用勘查资料进行准确的地质建模和逐级优化钻孔方案,对于降低勘查成本和提高地层数据收集效率具有十分重要的意义。由于岩土勘测初期钻孔数据通常十分稀少,而工程区域的地质结构可能随位置发生显著变化,这大大增加了钻孔设计的难度。CMC模型可以处理稀疏地质勘查数据,并且具有参数简单和理论简洁的优点,因此被广泛用在地质建模和地质不确定分析中。然而,已有的CMC模型无法用于复杂变化地层的钻孔设计,因为它们依赖全局的序列方向和Walther常数,可能导致对地质结构的错误估计。提出了一种基于局部耦合马尔科夫链模型(Local coupled Markov chain model,简称LCMC模型)进行额外钻孔优化的方法。该方法利用地质剖面钻孔数据的片段化处理、局部随机建模和多片段叠加的方式建立适应复杂变化地层的地质模型;使用基于LCMC模型生成的信息熵图定量评价地质单元的不确定性;基于柱平均信息熵曲线对额外钻孔的最佳位置进行逐步预测。研究结果表明,相比于传统方法,提出的方法可以实现更加合理高效的钻孔优化,增加倾角和方向发生变化的复杂地层的建模准确性,以及降低地质剖面模拟的不确定性。提出的方法为复杂变化地质区域的钻孔设计提供了一种有益的参考。

The rational use of exploration data for accurate geological modeling and the step-by-step optimization of drilling plans are of great importance for reducing the exploration costs and improving the efficiency of stratigraphic data collection.Due to the typically sparse borehole data at the early stage of geotechnical surveying and the potential for significant variations in the geological structure across different locations within the project area,the difficulty of borehole design is greatly increased.The CMC model can handle sparse geological exploration data and is widely used in geological modeling and geological uncertainty analysis due to its simple parameters and straightforward theory.However,the existing CMC models cannot be used for the borehole design in complexly varying strata because they rely on the global sequence direction and the Walther’s constant,which may lead to incorrect estimates of geological structures.A method for optimizing the additional boreholes is proposed based on the local coupled Markov chain model(LCMC model).This method establishes a geological model that adapts to complex and varying strata by fragmenting borehole data from geological profiles,employing local stochastic modeling,and overlaying multiple fragments;it uses an entropy map generated by the LCMC model to quantitatively evaluate the uncertainty of geological units;and it progressively predicts the optimal locations for the additional boreholes based on the column-averaged entropy curve.The research results show that,compared to the traditional methods,the proposed approach can achieve more reasonable and efficient borehole optimization,increase the modeling accuracy of complex strata with changing dips and directions,and reduce the uncertainty in geological profile simulations.The proposed method offers a the beneficial reference for borehole design in geologically complex and variable regions.