Abstract

Establishing effective seismic survey parameters in complex structural areas, such as salt domes, is of vital importance for accurate imaging. Shot and group intervals, maximum offset, recording time and profile length, to image the subsurface structures, are critical 2-D parameters. Geometry, aspect ratio of a recording patch and number of in-line and cross-lines are key additional parameters for 3-D seismic design. This study provides a workflow for determining optimal 2-D and 3-D seismic survey parameters as exemplified by a Texas salt dome case. The Pierce Junction oil field, in proximity to the salt dome, is located in Houston, Texas, and has been one of the most prolific hydrocarbon producers in the region. Engineered caverns in the salt dome itself are now used for fluid storage. Design parameters for the future seismic surveys are partially informed by previous seismic data shot over the structure (where the top of the salt is at about 290 m depth and overlying cap rock, 210 m). Existing 2-D seismic data, crossing the salt dome, are processed to extract the velocities of the salt, cap rock, and near-surface sediments. In the following step, 2-D and 3-D velocity models of the study area are constructed using legacy well data as well as gravity measurements which were acquired as part of this study. Synthetic shot gathers are next modeled with a finite difference method using the acoustic wave equation. To generate images of the constructed model, reverse time migration (RTM) is applied to the synthetic data. By assessing the coverage and continuity of the imaged salt boundaries using a variety of decimated input data sets, the optimal survey parameters are determined. In this case, 20 m group and 40 m shot interval, 3000 m maximum offset, and 8 km profile length with a 4 s recording time are found to be most favorable 2-D acquisition parameters. Using similar coverage and continuity criteria, group and shot intervals of a 3-D seismic survey are determined as 25 m and 50 m, respectively. The receiver and shot line intervals are chosen as 250 m in an orthogonal geometry with 33 in-lines and 33 cross-lines distributed in the 8 × 8 km² survey area. The aspect ratio of any patch with 13 in-lines and 13 cross-lines is accepted as 1:1. This forward modeling and migration procedure, using a range of decimated data sets, can inform decisions on the final field parameters.

中文翻译：

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通过建模和逆时偏移进行 2-D 和 3-D 地震勘测的优化设计：Pierce Junction Salt Dome, Texas

摘要

在盐丘等复杂结构区域建立有效的地震勘探参数对于精确成像至关重要。拍摄和分组间隔、最大偏移、记录时间和轮廓长度，以对地下结构进行成像，是关键的二维参数。几何形状、记录块的纵横比以及在线和交叉线的数量是 3-D 地震设计的关键附加参数。本研究提供了确定最佳 2-D 和 3-D 地震勘测参数的工作流程，例如德克萨斯盐丘案例。Pierce Junction 油田靠近盐丘，位于德克萨斯州休斯顿，是该地区最多产的碳氢化合物生产商之一。盐丘本身的工程洞穴现在用于储存液体。未来地震勘测的设计参数部分来自先前在结构上拍摄的地震数据（其中盐顶深度约 290 m，上覆盖层 210 m）。对穿过盐丘的现有二维地震数据进行处理，以提取盐、盖层和近地表沉积物的速度。在接下来的步骤中，研究区域的 2-D 和 3-D 速度模型是使用遗留井数据以及作为本研究的一部分获得的重力测量构建的。接下来使用声波方程用有限差分方法对合成炮点道集进行建模。为了生成构建模型的图像，逆时迁移 (RTM) 应用于合成数据。通过使用各种抽取的输入数据集评估成像盐边界的覆盖范围和连续性，确定最佳调查参数。在这种情况下，发现 20 m 组和 40 m 射击间隔、3000 m 最大偏移和 8 km 剖面长度和 4 s 记录时间是最有利的二维采集参数。使用类似的覆盖范围和连续性标准，3-D 地震勘测的组和炮间隔分别确定为 25 m 和 50 m。接收器和射击线间隔在正交几何中选择为 250 m，其中 33 条直线和 33 条交叉线分布在 8 × 8 km 3-D 地震勘测的组和炮间隔分别确定为 25 m 和 50 m。接收器和射击线间隔在正交几何中选择为 250 m，其中 33 条直线和 33 条交叉线分布在 8 × 8 km 3-D 地震勘测的组和炮间隔分别确定为 25 m 和 50 m。接收器和射击线间隔在正交几何中选择为 250 m，其中 33 条直线和 33 条交叉线分布在 8 × 8 km²调查区。任何具有 13 行和 13 行交叉线的补丁的纵横比都被接受为 1:1。这种使用一系列抽取数据集的正向建模和迁移过程可以为最终现场参数的决策提供信息。