Improved Amott Tests Help Quantify Primary Driving Forces in Spontaneous Imbibition in Water-Wet and Oil-Wet Limestone Rock

Kaprielova, Ksenia; Yutkin, Maxim; Gmira, A.; Ayirala, Subhash C.; Yousef, Ali; Radke, Clayton J.; Patzek, Tadeusz W

doi:10.2118/213450-ms

Cited by 4 publications

(2 citation statements)

References 32 publications

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“…We started by capping the top and bottom faces of the vertical core plugs to 1) minimize the axial flow, thereby simplifying the modeling process, and to 2) to prevent the retention of oil droplets on the top face of the core samples. Both effects are more pronounced in experiments involving crude oil and low oil/brine interfacial tension [49]. In this manuscript, we exclusively test water-wet cores saturated with mineral oil.…”

Section: Modified Amott-cell Experimentsmentioning

confidence: 99%

Improved Amott Method to Determine Oil-Recovery Dynamics from Water-Wet Limestone using GEV Statistics

Kaprielova,

Yutkin,

Mowafi

et al. 2024

Preprint

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Counter-current spontaneous imbibition of water is a critical oil-recovery mechanism. In the laboratory, the Amott test is a widely used technique to assess efficacy of brine imbibition into oil-saturated core plugs. The classic Amott-cell methodology was designed to estimate ultimate oil recovery, but not the recovery dynamics that provides essential information about the imbibition mechanisms. Retention of oil droplets at the external core surface and delayed onset of oil production are the two key artifacts of the classic Amott experiment. This retention, referred to here as the ``external-surface oil holdup effect'', often results in stepwise recovery curves that obscure true dynamics of spontaneous imbibition. To address these holdup drawbacks of the classic Amott method, we modified the Amott cell and experimental procedure. For the first time, using water-wet Indiana limestone cores saturated with brine and mineral oil, we showed that our improvements of the Amott method enabled accurate and reproducible measurements of oil-recovery dynamics. We used the Generalized Extreme Value (GEV) statistics to describe oil-production histories from water-wet heterogeneous limestone cores with finite initial water saturations, for the first time. We demonstrated that our four-parameter GEV model accurately described the recovery dynamics, and that optimal GEV parameter values systematically reflected the key characteristics of the oil-rock system, such as oil viscosity and rock permeability. These findings gave us a more fundamental understanding of spontaneous, counter-current imbibition mechanisms and insights into what constitutes a predictive model of counter-current water imbibition into oil-saturated rocks with finite initial water saturation.

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Section: Modified Amott-cell Experimentsmentioning

confidence: 99%

Improved Amott Method to Determine Oil-Recovery Dynamics from Water-Wet Limestone using GEV Statistics

Kaprielova,

Yutkin,

Mowafi

et al. 2024

Preprint

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“…This experiment is simple to conduct; however, it does not fully replicate the actual field conditions, where imbibition occurs within the porous media, i.e., from one rock type to another. 23,25 This poor representation of field conditions may underestimate the full potential of the imbibition mechanism. Moreover, this method is inadequate to capture the micro-scale processes of the counter-current flow dynamics.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of Spontaneous Imbibition in Multilayered Porous Systems

et al. 2023

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Spontaneous imbibition is a fundamental fluid flow mechanism that plays a significant role in various applications of multiphase fluid flow in porous media, including oil extraction from subsurface reservoirs and underground carbon dioxide storage. Understanding the dynamics of imbibition, driven by capillary forces across multilayered systems, is essential for designing and optimizing field applications. Laboratory experiments with the traditional Amott cell, commonly used to quantify the imbibition performance by immersing an oil-saturated core plug in water and measuring the extracted oil, do not fully replicate actual reservoir conditions. Under reservoir conditions, imbibition occurs within the porous formations across different rock types, while in the Amott cell, imbibition occurs between the rock and the open surrounding water medium. This misrepresentation of field conditions may not replicate the true potential of imbibition. In this study, we use micro-CT and dynamic pore-scale imaging as an alternative approach to visualize and quantify rock-to-rock imbibition within heterogeneous porous media, which cannot be achieved with traditional methods. This work aims at introducing a new concept to evaluate the imbibition mechanism across different porous formations, reflecting the conditions of multilayer systems in the subsurface.

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Universal Scaling of Counter-Current Spontaneous Imbibition Experiments Accounting for Sample Shape, Wettability, Saturation Functions and Other Input Parameters

Andersen

2024

Adipec

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Spontaneous imbibition (SI) refers to multiphase fluid flow driven by capillary forces. In particular, counter-current (COU) SI is a flow setting where the wetting phase invades the sample while the non-wetting phase flows in the opposite direction (counter-currently). This is facilitated by exposing all open sides of the sample to the wetting phase. COU SI is among the most common experiments performed on porous media core samples. An important application of those tests is to estimate the rate of SI and ultimate recovery on larger scale, e.g. in naturally fractured reservoirs for assessing oil production from the matrix blocks or to assess water losses during hydraulic fracturing in tight shales. This is performed by converting the time scale seen in the laboratory to a time scale corresponding to the metric dimensions in the field. Current approaches are based on taking a time scale obtained from the 1D (linear) capillary diffusion equation while applying a characteristic length to correct for flow into samples that do not have linear flow, such as cylindrical or otherwise. While a semi-analytical solution does exist that perfectly scales 1D flow tests for all conditions (although only at early time), the use of a characteristic length is only approximate and it is unclear how accurate or inaccurate the results can be. In a recent work it was demonstrated that imbibition into samples of arbitrary geometry could be accounted for in a highly accurate manner. While 1D flow results in recovery linear with the square root of time at early time, such linearity occurs until a much lower value of recovery for samples with flow from more sides open. This work aims to apply those results to assess different scaling approaches: In the first approach all samples have identical initial imbibition rate against scaled square root of time. While this works well for 1D samples, the rate of recovery declines soon for the complex geometry cases. An alternative, which still collects the 1D samples perfectly, focuses on giving similar recovery for all cases at a higher level of recovery. Both approaches are theory based and do not require any tuning parameters. The theory is tested on numerical simulations and experimental data. The scaling collects data on a unit slope line of recovery against square root of scaled time. It is demonstrated that experimental data that can be modeled consistently (using the same set of input parameters) can be scaled more successfully.

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Improved Amott Tests Help Quantify Primary Driving Forces in Spontaneous Imbibition in Water-Wet and Oil-Wet Limestone Rock

Cited by 4 publications

References 32 publications

Improved Amott Method to Determine Oil-Recovery Dynamics from Water-Wet Limestone using GEV Statistics

Improved Amott Method to Determine Oil-Recovery Dynamics from Water-Wet Limestone using GEV Statistics

Experimental and Numerical Investigation of Spontaneous Imbibition in Multilayered Porous Systems

Universal Scaling of Counter-Current Spontaneous Imbibition Experiments Accounting for Sample Shape, Wettability, Saturation Functions and Other Input Parameters

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