Title: Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO ₂ , Methane, and Ethane

Abstract

Here, we report a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2-4 MMP values can be determined per day with only one experimental apparatus, and the method greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Willistonmore » Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO₂, methane, and ethane as well as 0-100% mole ratios of methane/CO₂ and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO₂, while methane MMPs were ca. double or triple those with CO₂. MMPs with mixed methane/CO₂ showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

Authors:

Hawthorne, Steven B. ^[1]; Miller, David J. ^[1]; Jin, Lu ^[1]; Gorecki, Charles D. ^[1]

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+ Show Author Affiliations

1. Energy & Environmental Research Center, University of North Dakota, 15 North 23rd Street, Stop 9018, Grand Forks, North Dakota 58202, United States

Publication Date:

Wed Jul 20 00:00:00 EDT 2016

Research Org.:

National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States); Univ. of North Dakota, Grand Forks, ND (United States)

Sponsoring Org.:

USDOE; North Dakota Industrial Commission. Dept. of Mineral Resources, Oil and Gas Division; Plains CO2 Reduction Partnership (PCOR)

OSTI Identifier:

1619422

Alternate Identifier(s):

OSTI ID: 1438466

Grant/Contract Number:  

FC26-05NT42592; G-030-060

Resource Type:

Published Article

Journal Name:

Energy and Fuels

Additional Journal Information:

Journal Name: Energy and Fuels Journal Volume: 30 Journal Issue: 8; Journal ID: ISSN 0887-0624

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

02 PETROLEUM