Drillhole uncertainty propagation for three-dimensional geological modeling using Monte Carlo
Drillhole uncertainty propagation for three-dimensional geological modeling using Monte Carlo
复制标题
使用蒙特卡罗进行三维地质建模的钻孔不确定性传播
DOI：
10.1016/j.tecto.2018.09.005
复制
发表时间：
2018
期刊：
影响因子：
2.9
通讯作者：
M. Jessell
中科院分区：
文献类型：
--
作者：
Evren Pakyuz;J. Giraud;V. Ogarko;M. Lindsay;M. Jessell
蒙特卡罗不确定性估计（MCUE）是一种新兴的启发式不确定性传播方法，旨在提供可靠且时间/成本有效的几何不确定性估计。MCUE是贝叶斯蒙特卡罗方法的一个子类型，类似于地质统计模拟。这里描述的方法依赖于参数化的干扰概率分布，以最好地代表个人的输入不确定性。从本质上讲，扰动分布量化了关于观测到的地质结构的位置（x，y，z）和取向（倾角和方位角）的误差。扰动分布被独立采样或通过马尔可夫链采样，以产生许多合理的替代数据集。然后将这些合理的数据集输入到3D地质建模引擎，以构建一系列合理的替代模型实现。进一步的处理可以应用到一系列的合理的模型，以提供有价值的决策辅助工具，如概率模型，可靠性模型，或不确定性减少热点maps.In本文中，一个完整的和全面的MCUE过程中提出的共同钻孔路径和日志不确定性传播。介绍了钻孔不确定性的基本概念，并将其应用于马尔可夫链方案。适当的扰动分布的不同部分的问题和各自的参数化进行了讨论。所提出的方法证明了三个独立的概念证明案例研究的复杂性不断增加。结果表明，该方法能够适当地传播路径和日志的不确定性。一阶解释表明，路径和测井不确定性都随着深度和对地质界面的攻角而增加。忽略钻孔的不确定性被认为是有害的理解的一个模拟的区域，这是最有可能的是由于过度约束的效果所带来的“完美”的钻孔。第三个案例研究（曼斯菲尔德）暗示，当钻孔与划分三种不同岩性的“三线”相交时，不确定性会更好地降低。在横截面中，三重线显示为三重点。
Monte Carlo Uncertainty Estimation (MCUE) is an emerging heuristic uncertainty propagation method designed to provide reliable and time/cost efficient estimates of geometrical uncertainties in 3D geological modeling. MCUE is a subtype of Bayesian Monte Carlo method similar to geostatistical simulation. The methods described here rely on disturbance probability distributions that are parameterized to best represent individual input uncertainty. Essentially, disturbance distributions quantify the error about the location (x, y, z) and orientation (dip and azimuth) of observed geological structures. The disturbance distributions are sampled either independently or via a Markov-Chain to produce many plausible alternative datasets. These plausible datasets are then input to a 3D geological modeling engine to build a series of plausible alternative model realizations. Further processing may be applied to the series of plausible models to provide valuable decision aids such as probabilistic models, reliability models, or uncertainty reduction hotspot maps.In this paper, a complete and comprehensive MCUE procedure for common drillhole path and log uncertainty propagation is proposed. Basic concepts of drillhole uncertainty are introduced and are applied to a Markov Chain scheme. Appropriate disturbance distributions for the different parts of the problem and their respective parameterization are discussed. The method proposed is demonstrated on three separate proof of concept case studies of increasing complexity. Results demonstrate that the method is able to propagate path and log uncertainty appropriately. First order interpretation indicates that both path and log uncertainty increase with depth and angle of attack to the geological interfaces. Ignoring drillhole uncertainty was found to be detrimental to the understanding of a modeled area which is most likely due to the over-constraining effect brought by “perfect” drillholes. The third case study (Mansfield) hints that uncertainty is better reduced when drillholes intersect the “triple line” that partitions three distinct lithologies. In cross-sections, triples lines appear as triple points.