Dissolving CO₂ into water or brine produces a denser fluid than the CO₂-free equivalent at all salinity, temperature and pressure conditions relevant to sedimentary basins. Negative buoyancy of CO₂ solutions opens the possibility of utilizing negative-relief trapping configurations for CO₂ sequestration, as opposed to structural highs conventionally sought for positively buoyant fluids, such as hydrocarbons or pure CO₂. Exploring sedimentary basins for negative buoyancy traps can readily utilize hydrocarbon exploration datasets and techniques. Some major systemic differences when exploring for negative as opposed to positive buoyancy traps are examined here. Trap spatial scale is a consideration due to the inherent long-wavelength synformal geometry of basins. Antiforms are areally restricted relative to synforms, which may be embedded within larger-scale synformal closure at length scales right up to that of the basin itself. Multiscale synformal structures vary with basin type and may not be fully identified due to truncation effects arising from data-coverage limitations. Similar to hydrocarbon exploration, CO₂ trap exploration must consider potential sequestration volumes in an uncertainty and risk framework. Charge risk is unnecessary in sequestration projects; however, the multiscale nature of synformal traps should be considered when estimating the range of storage volumes.

Thematic collection: This article is part of the Geoscience for CO₂ storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

在与沉积盆地相关的所有盐度、温度和压力条件下，将 CO ₂溶解到水或盐水中会产生比不含CO _{2 的}等效物更稠密的流体。CO ₂溶液的负浮力开启了利用负浮雕捕集配置来封存CO ₂的可能性，这与传统上寻求正浮力流体（例如碳氢化合物或纯 CO _2）的结构高点相反. 探索负浮力圈闭的沉积盆地可以很容易地利用油气勘探数据集和技术。此处检查了探索负浮力陷阱与正浮力陷阱时的一些主要系统差异。由于盆地固有的长波长同形几何，圈闭空间尺度是一个考虑因素。相对于同形体，反形体在区域上受到限制，其可以嵌入到更大规模的同形体闭合中，其长度尺度一直到盆地本身的长度。多尺度同形结构因盆地类型而异，并且由于数据覆盖范围限制引起的截断效应，可能无法完全识别。与油气勘探类似，CO ₂圈闭勘探必须在不确定性和风险框架中考虑潜在的封存量。封存项目不需要充电风险；然而，在估计存储量范围时，应考虑同形陷阱的多尺度性质。

专题合集：本文是地球科学 CO ₂储存合集的一部分，可在以下网址获取：https://www.lyellcollection.org/cc/geoscience-for-co2-storage