MARLIM R3D - A REALISTIC MODEL FOR mCSEM SIMULATION

The marine Controlled-Source Electromagnetic (mCSEM) method provides complementary information to seismic imaging in the exploration of sedimentary basins. The mCSEM can be used to help in subsalt structural imaging, but mainly for reservoir scanning and appraisal as EM methods are especially sensible to the fluid content within the rocks. The mCSEM interpretation workflow is heavily based on inversion and forward--modeling for hypothesis testing. Until the recent past, the effectiveness of a given interpretation workflow was achieved after the drilling results, as there wasn't any geological complex model available to serve as a benchmark. The Society of Exploration Geophysics (SEG) recognized that gap and launched the SEAM (SEG Advanced Modeling)-Phase I project aiming to advance the geophysical science through the construction of a multi-physics subsurface model and generation of an associated dataset. SEAM Phase-I, a representation of the deepwater Gulf of Mexico salt domain, was designed to take as much realism and geological complexity as possible. Following the success of that first model, SEG launched SEAM Phase-II focused on the solution of land seismic challenges like near-surface complexities and fractured reservoirs. In the present publication, we will also describe the workflow to build Marlim--R3D, a realistic and complex geoelectric model. Marlim-R3D aims to be a reference model for mcSEM modeling and inversion studies of turbidite reservoirs of the Brazilian continental margin. Our model is based on previous seismic interpretation and constrained by the input of available well-log information. The workflow used is composed of seven sequential steps: seismic and well-log dataset loading, well-tie, Vp (P-wave velocity) cube construction, Vp-resistivity calibration, time-depth conversion, resistivity cube construction, Quality-control check. As a result, we obtained an interpreted dataset composed by main stratigraphic horizons, pseudo-well logs, and the resistivity cubes. These elements will be freely available for research or commercial use, under the Creative Common License. Files Description : Depth horizons: *xyz extension (Upper Oligocene, Upper Miocene, Sea Bottom, Top of Marlim Reservoir, Top and Base of the Salt) Pseudo Wells: *.LAS extension (extrated properties from modelling) ------- *.track extensions (well track) 3D Cubes: *sgy Horizontal & Vertical Resistivity (Calculated resistivity from modelling - horizontal and vertical anisotropy) Log(RESH) & Log(RESV) files are the resistivity cubes but in common logarithmic scale

海洋可控源电磁（marine Controlled-Source Electromagnetic, mCSEM）方法在沉积盆地勘探中可作为地震成像的补充手段。mCSEM可辅助盐下构造成像，但其主要应用场景为储层扫描与评价——这是因为电磁方法对岩石内部的流体含量尤为敏感。mCSEM解释工作流主要基于反演与正演模拟开展假设检验。在不久之前，特定解释工作流的有效性仍需待钻井结果出炉后才能验证，彼时尚无可用的复杂地质模型可作为基准。勘探地球物理学家协会（Society of Exploration Geophysics, SEG）注意到这一研究空白，发起了SEAM（SEG Advanced Modeling）一期项目，旨在通过构建多物理场地下模型并生成配套数据集推动地球物理科学发展。SEAM一期项目复刻了墨西哥湾深水盐构造域，设计时尽可能还原真实地质场景与复杂性。在该首个模型取得成功后，SEG又发起了SEAM二期项目，聚焦解决陆上地震面临的近地表复杂性、裂缝性储层等挑战。在本出版物中，我们还将介绍Marlim-R3D模型的构建工作流——这是一个兼具真实性与复杂性的地电模型。Marlim-R3D旨在作为巴西大陆边缘浊积岩储层mCSEM建模与反演研究的参考模型。本模型基于已有地震解释成果，并以现有测井资料作为约束条件。所采用的工作流包含七个连续步骤：地震与测井数据集加载、井震标定、纵波速度（Vp）体构建、Vp-电阻率校准、时深转换、电阻率体构建、质量控制检查。最终我们得到了由主要地层层面、伪测井曲线以及电阻率体组成的解释数据集。这些资料将在知识共享许可协议下免费开放，可用于科研或商业用途。文件说明：
深度层面：*xyz格式（包括渐新统上部、中新统上部、海底、Marlim储层顶部、盐层顶部与底部）
伪测井井：*.LAS格式（提取自模拟的物性数据）
*.track格式（井轨迹）
3D体数据：*sgy格式（水平与垂直电阻率——通过模拟计算得到的考虑各向异性的水平、垂直电阻率）
Log(RESH)与Log(RESV)文件为转换为常用对数刻度的电阻率体