We demonstrate how modelling decisions for a giant carbonate reservoir with a thick transition zone in the Middle East, most notably the approach to reservoir rock typing and modelling the initial fluid saturations, impact the hydrocarbon distributions and oil-in-place estimates in the reservoir. Rather than anchoring our model around a single base case with an upside and downside, we apply a comprehensive 3D multiple deterministic scenario workflow to compare-and-contrast how modelling decisions and geological uncertainties influence the volumetric estimates. We carry out a detailed analysis which shows that the variations in STOIIP estimates can be as high as 28% depending on the preferred modelling decision, which could potentially mask the impact of other geological uncertainties. These models were validated through repeated and randomised blind tests. We hence present a quantitative approach that helps us to assess if the static models are consistent in terms of the integration of geological and petrophysical data. Ultimately, the decision which of the different modelling options should be applied does not only influence STOIIP estimates, but also subsequent history matching & forecasts.

我们展示了对中东具有厚过渡带的巨型碳酸盐储层的建模决策，尤其是储层岩石类型和初始流体饱和度建模的方法，如何影响储层中的碳氢化合物分布和就地油估计。我们不是将我们的模型锚定在一个具有优势和劣势的基础案例上，而是应用全面的 3D 多确定性场景工作流程来比较和对比建模决策和地质不确定性如何影响体积估计。我们进行了详细的分析，结果表明 STOIIP 估计的变化可能高达 28%，具体取决于首选的建模决策，这可能会掩盖其他地质不确定性的影响。