{"id":220440,"date":"2026-01-22T14:56:25","date_gmt":"2026-01-22T12:56:25","guid":{"rendered":"https:\/\/azbuki.bg\/?p=220440"},"modified":"2026-01-26T09:37:51","modified_gmt":"2026-01-26T07:37:51","slug":"new-technology-for-developing-hydrocarbon-reserves-of-complex-reservoirs-with-underlying-water","status":"publish","type":"post","link":"https:\/\/mathinfo.azbuki.bg\/en\/uncategorized\/new-technology-for-developing-hydrocarbon-reserves-of-complex-reservoirs-with-underlying-water\/","title":{"rendered":"New Technology for Developing Hydrocarbon Reserves of Complex Reservoirs with Underlying Water"},"content":{"rendered":"

Miel Hofmann, Sudad H. Al-Obaidi <\/strong><\/p>\n

Mining University, Russia<\/em><\/p>\n

Igor P. Kamensky<\/strong><\/p>\n

Scientific Research centre<\/em>, <\/em>Russia<\/em><\/p>\n

https:\/\/doi.org\/10.53656\/nat2025-4.06<\/a><\/p>\n

Abstract. <\/strong>This study presents a novel technique for developing complex oil reservoirs with bottom water. The method involves injecting freshwater below the oil-water contact (OWC) and subsequently stabilizing it with a polymer to create a barrier. This approach is designed to reduce water cut, enhance oil recovery (EOR), and sustain production rates in mature fields.<\/p>\n

Based on an analysis of experimental and field data, criteria for the technology’s application have been established. A key mechanism is the reduction of permeability in terrigenous reservoirs following freshwater injection, a phenomenon confirmed by laboratory core studies. Using a radial hydrodynamic model, this study assessed the technology’s effects and performed a sensitivity analysis to optimize perforation placement and injected agent volume. The results can be used to evaluate not only freshwater but also other water-control agents, although field-specific core flow studies are necessary to justify any application.<\/p>\n

The model also identified two primary mechanisms of bottom water inflow to production perforations. The first is water coning, which is driven by production-induced pressure gradients. The second mechanism is channeling along the casing string, which is caused by factors like poor cement quality or the presence of natural and induced fractures. Finally, a calculation of production losses resulting from this water flow was performed.<\/p>\n

Keywords: <\/em>Freshwater, OWC, Underlying water, Water cut, EOR<\/p>\n

\u00a0<\/strong><\/p>\n

    \n
  1. Introduction<\/strong><\/li>\n<\/ol>\n

    The primary focus of the modern oil and gas industry is to enhance the efficiency of hydrocarbon extraction from complex fields at a late stage of development. A large proportion of these hydrocarbon reserves are found in fields classified as \u201cwith bottom water\u201d or water-floating (Al-Obaidi & Khalaf, 2019; Asuaje et al., 2025; Huang & Lin, 2020; Yang et al., 2022). Developing these areas is complicated by the rapid formation of a water cone drawn up toward vertical wells due to pressure depletion.<\/p>\n

    Currently, various agents and methods (gels, polymers, alkalis, fresh water, etc.) are used to limit water inflow (WIL) in complex oil and gas fields (Bai et al., 2023; Chang et al., 2021] Foutou et al., 2021; Han et al., 2022). These methods fundamentally aim to reduce the permeability of highly permeable, water-washed zones within the formation, allowing the low-permeability sections to be effectively utilized. A wide range of action mechanisms is known. In each specific case, the chosen method depends on the reservoir type, the geological structure of the deposit, and the technical and economic conditions (Al-Obaidi, 2015; Hassan et al., 2022; Malozyomov et al., 2023; Xu et al., 2020;).<\/p>\n

    One popular area of development is the use of fresh water, primarily due to its low cost compared to specialized chemical agents (gels, polymers, alkalis, surfactants). The effect of fresh water on permeability varies between high- and low-permeability reservoirs. In low-permeability, clay-filled reservoirs, a permeability reduction occurs due to clay swelling (Bourg & Ajo-Franklin, 2017; Liu et al., 2021; Zhao et al., 2024).<\/p>\n

    In highly permeable reservoirs with a low degree of clay content, permeability may also decrease due to migration of fine particles. Several studies (Chen et al., 2023; Knobloch et al., 2018; Li et al., 2023; Ligeiro et al., 2021) have performed qualitative and quantitative calculations of permeability reduction (ranging from 10 to 1000 times) during fresh water injection. It has been shown that in terrigenous reservoirs, introducing fresh water reduces the Van der Waals forces that hold fine particles on the pore walls. As a result, the fine particles migrate toward the pore throats. These particles then clog the narrow pore throats, generally resulting in a sharp decrease in permeability.<\/p>\n

    Experiments on oil displacement using various agents were carried out on linear core models (Al-Obaidi et al., 2022; Drozdov, 2022; Liu et al., 2020). The results demonstrated a 4-to-11-fold decrease in effective permeability for sandstones of the terrigenous Carboniferous strata during flooding with fresh (river) water (Fig. 1). It was concluded that fresh water is not recommended for flooding terrigenous deposits of the Lower Carboniferous due to its significant negative impact on the formation’s flow properties. Based on these studies, the reservoir pressure maintenance system transitioned to using bottom and formation water.<\/p>\n

    \"\"<\/p>\n

    Figure<\/strong> 1.<\/strong> Linear core model with reduced effective permeability under freshwater displacement<\/p>\n

     <\/p>\n

    This paper considers a technological solution: injecting a freshwater rim into the WOC zone to reduce permeability. This aims to delay bottom water breakthrough while simultaneously decreasing water cut and increasing oil production.<\/p>\n

    \u00a0<\/strong><\/p>\n

      \n
    1. Methodology and materials <\/strong><\/li>\n<\/ol>\n

      The modeling approach utilizes the freshwater rim technique, which functionally resembles polymer flooding (Agi et al., 2018; Ding et al., 2020; Rai et al., 2015; Wang et al., 2022). This simulation is executed using the Eclipse 100 reservoir simulator, leveraging its dedicated Polymer section to model the effects of freshwater on the terrigenous formation.<\/p>\n

      2.1 Simulation Parameters<\/strong><\/p>\n

      The interaction between the freshwater and the reservoir rock is defined by standard polymer modeling parameters, including the Recovery Resistance Factor (RRF) and the adsorption curve. The impact of freshwater on formation properties is explicitly implemented using the simulator keywords (Al-Obaidi et al., 2023; Ekanem et al., 2021; Haq et al., 2019; Olabode et al., 2024):<\/p>\n

      \u2013 Plyrock (Polymer rock properties)<\/p>\n

      \u2013 Plyads (Polymer Adsorption Functions)<\/p>\n

      2.2.\u00a0 Hydrodynamic Model Design<\/strong><\/p>\n

      The model employs a variable-resolution grid optimized for accuracy in the critical zone and efficiency in the far-field.<\/p>\n

      \u2013 Near-Wellbore Zone: A high-precision grid is used, with a fine resolution of 0.1\u00d70.1\u00d70.1\u00a0m, ensuring an accurate description of dynamic processes immediately surrounding the wellbore.<\/p>\n

      \u2013 Periphery: The grid is systematically coarsened, with the dr<\/em> parameter increasing up to 100\u00a0m at the model’s periphery.<\/p>\n

      The overall grid consists of 6,000 cells. This strategic coarsening maintains computational efficiency, resulting in a rapid calculation time that does not exceed 5 minutes. The primary objective of the hydrodynamic model is to simulate processes within the bottom-hole zone, specifically for optimizing Water Inflow Limitation (WIL) techniques (Luo et al., 2023; Sharma et al., 2000; Yudin et al., 2024).<\/p>\n