用蒙特卡罗模拟量化与方解石胶结层有关的AVO不确定性

IF 1.1 4区 地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS
S. Tschache, V. Vinje, J. Lie, E. Iversen
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引用次数: 0

摘要

方解石胶结通常在局部形成薄层方解石胶结砂岩,其特征是高地震速度和密度。由于方解石胶结层段与周围岩石具有强烈的阻抗对比,因此会产生可探测的地震反射信号,这些信号可能会干扰储层顶部的目标反射。在这种情况下,有效地震信号的振幅随偏移量的变化(AVO)将被改变,甚至可能产生错误的油气指示。蒙特卡罗模拟发现,薄方解石胶结层的存在增加了基于AVO属性截距和梯度的贝叶斯孔隙流体分类的不确定性。以北海浊积油气田为例,假设存在卤水、石油和天然气的概率相同,油气指示误报的概率从3-5%增加到18-21%。结果表明,方解石胶结层在AVO分析中存在缺陷。AVO不确定性的现实估计对于井位决策的风险评估至关重要。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Quantifying AVO uncertainties related to calcite-cemented beds using Monte Carlo simulation
Calcite cement often occurs locally forming thin layers of calcite-cemented sandstone characterized by high seismic velocities and densities. Because of their strong impedance contrast with the surrounding rock, calcite-cemented intervals produce detectable seismic reflection signals that may interfere with target reflections at the top of a reservoir. In this case, the amplitude variation with offset (AVO) of the effective seismic signature will be altered and may even create a false hydrocarbon indication. From Monte Carlo simulation, we find that the presence of thin calcite-cemented beds increases the uncertainty of Bayesian pore-fluid classification based on the AVO attributes intercept and gradient. In the case example of a North Sea turbiditic oil and gas field, the probability of a false positive hydrocarbon indication increases from 3–5% to 18–21% assuming an equal probability of the occurrence of brine, oil, and gas. The results confirm that calcite-cemented beds can create a pitfall in AVO analysis. Realistic estimates of AVO uncertainty are crucial for the risk assessment of well placement decisions.
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来源期刊
CiteScore
2.50
自引率
8.30%
发文量
126
期刊介绍: ***Jointly published by the American Association of Petroleum Geologists (AAPG) and the Society of Exploration Geophysicists (SEG)*** Interpretation is a new, peer-reviewed journal for advancing the practice of subsurface interpretation.
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