ABSTRACT Various methods were earlier designed to calculate porosity of a formation, but many of them are reliant on physical soil sampling and/or laboratory measurements. The present work examines a recently proposed method, which we call here as Sample‐free Porosity Calculation from Resistivity Imaging Data (SPyCRID), to calculate porosity of unconsolidated soils. By conjoining Archie's and Waxman–Smits’ equations, SPyCRID can achieve high accuracy in porosity calculation, while requiring no physical soil‐sampling data. Two‐dimensional resistivity data acquired at Segantang Garam were modelled to calibrate SPyCRID's workflow and to devise data constraints for marine clay and brackish pore‐fluid conditions. Measured porosities from soil samples were used only for calibration and validation purposes. With data transformation added into the workflow, the performance of SPyCRID was improved as it was possible to achieve more precise value for the calculated porosity (error ≤3.1%). The final step to establish SPyCRID's competency was implemented through testing SPyCRID at the Nibong Tebal test site that has similar geological conditions to the model. Results from this test site showed nominal errors (≤3.9%) in the calculated porosity. SPyCRID could successfully calculate the porosity of the unconsolidated, marine clayey soils with a confidence limit exceeding 96%, while requiring no physical sampling data.

中文翻译：

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一种使用二维电阻率法计算海相粘土矿床孔隙度的非常规方法

摘要 早先设计了多种方法来计算地层的孔隙度，但其中许多方法依赖于物理土壤采样和/或实验室测量。目前的工作检查了最近提出的一种方法，我们称之为电阻率成像数据的无样本孔隙率计算 (SPyCRID)，用于计算松散土壤的孔隙率。通过结合 Archie 方程和 Waxman-Smits 方程，SPyCRID 可以在孔隙度计算中实现高精度，同时不需要物理土壤采样数据。在 Segantang Garam 获得的二维电阻率数据被建模以校准 SPyCRID 的工作流程并设计海洋粘土和微咸孔隙流体条件的数据约束。从土壤样品中测得的孔隙率仅用于校准和验证目的。通过将数据转换添加到工作流程中，SPyCRID 的性能得到了提高，因为可以为计算出的孔隙率获得更精确的值（误差≤3.1%）。建立 SPyCRID 能力的最后一步是通过在与模型具有相似地质条件的 Nibong Tebal 试验场测试 SPyCRID 来实现的。该测试地点的结果显示计算出的孔隙率存在名义误差 (≤3.9%)。SPyCRID 可以成功计算松散的海洋粘质土壤的孔隙率，置信限超过 96%，同时不需要物理采样数据。通过在与模型具有相似地质条件的 Nibong Tebal 试验场测试 SPyCRID，实现了能力。该测试地点的结果显示计算出的孔隙率存在名义误差 (≤3.9%)。SPyCRID 可以成功计算松散的海洋粘质土壤的孔隙率，置信限超过 96%，同时不需要物理采样数据。通过在与模型具有相似地质条件的 Nibong Tebal 试验场测试 SPyCRID，实现了能力。该测试地点的结果显示计算出的孔隙率存在名义误差 (≤3.9%)。SPyCRID 可以成功计算松散的海洋粘质土壤的孔隙率，置信限超过 96%，同时不需要物理采样数据。