The southern sector of the Llanos Basin in Colombia is a heavy and extra-heavy crude oil province where it has been hypothesized that hydrodynamic flow has influenced the potential of hydrocarbon storage and production. In this area, the hydrodynamic flow and the geochemical nature of the fluids are thought to decrease the potential for hydrocarbon retention. This work provides a comprehensive view on the impact of the regional hydrodynamic flow on the retention of the heavy oil accumulations present in the reservoirs that are part of the most important regional flow unit identified in the Southern Llanos Basin. The Basal Flow Unit (BFU) constitutes a basin-scale flow unit that hydraulically and laterally connects rocks from the Cretaceous (west) to the Oligocene (east) and extends from the basin's southwestern margin up to hundreds of kilometers within the Llanos foreland basin, and whose main water recharge zone has been identified towards the eastern flank of the Serranía de la Macarena. To understand the impact of the physicochemical properties of the fluids on hydrocarbon retention, we analyze the relationship between hydraulic data and the main characteristics of the fluids present in the BFU as well as their spatial distribution. This analysis integrated information from hydraulic heads, SARA analysis (Saturates, Aromatics, Resins, and Asphaltenes), Whole Oil Gas Chromatography analysis, API-gravity, and oil densities. In addition, hydrochemical analyses of the primary ions were performed in groundwater samples from the BFU, which was integrated with deep resistivity data measured in producing and exploratory oil wells in the area. The results allowed identifying the southwestern corner of the southern Llanos Basin as the area with the highest hydrodynamic flow impact, and therefore, the area with the least potential for hydrocarbon retention. We attribute the main causes to: 1) the proximity to recharge areas, and 2) the low contrast of fluids densities (freshwaters and highly biodegraded heavy crude oils), implying high Tilt Amplification Factor (TAF) values (10–100). In addition, the highest values of hydraulic heads (200–400 m), groundwater with the lowest ion concentrations (up to < 5 ppm Cl⁻), highly biodegraded crude oils, and the presence of poorly developed geological structures with low dip angles occur in this area, which allows us to interpret that the water washing process has decreased the hydrocarbon retention potential for this sector of the Llanos basin. Furthermore, gradual changes in resistivities (decreasing eastward) and ions concentration (increasing eastward) in groundwaters suggest the eastern flank of the Serranía de la Macarena as the main recharge zone of meteoric waters into the BFU. Finally, numerical simulation techniques were used to analyze the behavior of hydrocarbon drainage under hydrodynamic conditions, obtaining a first approximation to the average linear groundwater flow velocities between 10⁻³ and 10⁻⁴ ft/day.

哥伦比亚 Llanos 盆地的南部是一个重质和超重质原油省份，据推测，水动力流影响了碳氢化合物的储存和生产潜力。在该地区，流体的流体动力流动和地球化学性质被认为降低了烃类滞留的可能性。这项工作提供了关于区域水动力流动对油藏中稠油聚集的影响的综合观点，这些油藏是在南部 Llanos 盆地确定的最重要的区域流动单元的一部分。基底流动单元 (BFU)构成了一个盆地规模的流动单元，它在水力和横向上将白垩纪（西部）的岩石连接到渐新世（东），从盆地西南边缘延伸至 Llanos 前陆盆地内数百公里，其主要补水区已确定为 Serraníade la Macarena 东侧。为了了解流体的物理化学性质对烃类保留的影响，我们分析了水力数据与 BFU 中存在的流体的主要特征及其空间分布之间的关系。该分析综合了来自液压头、SARA 分析（饱和物、芳烃、树脂和沥青质）、全油气层析的信息分析、API 比重和油密度。此外，对来自 BFU 的地下水样品进行了一次离子的水化学分析，并与该地区生产和勘探油井中测量的深电阻率数据相结合。结果允许将 Llanos 盆地南部的西南角确定为具有最大水动力流动影响的区域，因此，该区域具有最小的油气滞留潜力。我们将主要原因归因于：1）靠近补给区，2）流体密度（淡水和高度生物降解的重质原油）的低对比度，这意味着高倾斜放大因子（TAF）值（10-100）。此外，水头最高（200–400 m），地下水离子浓度最低（高达 < 5 ppm Cl⁻ )、高度生物降解的原油和低倾角的欠发达地质结构的存在使我们能够解释水洗过程降低了 Llanos 盆地该区域的碳氢化合物保留潜力。此外，地下水电阻率（向东降低）和离子浓度（向东增加）的逐渐变化表明，Serrania de la Macarena 的东侧是大气水进入 BFU 的主要补给区。最后，数值模拟技术用于分析水动力条件下烃类排放的行为，获得了^{10 -3}和 10 ^-4之间平均线性地下水流速的第一个近似值。 英尺/天。