Executive overview · CO₂ EOR pressure response

Does recovery stop improving at the MMP?

Measured miscibility. Slim-tube measurements across six CO₂–crude systems place the minimum miscibility pressure between 1,373 and 2,132 psig.

Eagle Ford huff-n-puff. Recovery rose from 1.00% OOIP at 1,450 psig to 49.31% at 3,500 psig, beyond the 2,132-psig MMP for that system.

Gravity-stable coreflood comparison. At 1,100 psig, vertical floods recovered 90.4% and horizontal floods 33.5%. This separate comparison illustrates the effect of orientation.

CO₂–crude systems

2,132 psig

Eagle Ford MMP

49.31%

OOIP at 3,500 psig

+56.9 pts

Vertical − horizontal at 1,100 psig

Definition. The minimum miscibility pressure is the lowest pressure at which the injected gas and the reservoir oil become miscible through a multi-contact process at reservoir temperature (SPE-191752).

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

What's in this report

Source records3 measured records · 3 schematics

SPE-179673

Fast-slim-tube MMP

Six systems, 1,373–2,132 psig, plotted on the slim-tube and cross-comparison panes.

Measured

SPE-191752

Eagle Ford huff-n-puff

Five ultimate-recovery points, 1,450–3,500 psig, and the 2,132-psig MMP.

Measured

SPE-190183

GAGD orientation

Horizontal and vertical corefloods at three pressures for two systems.

Measured

Coreflood CT planes

Geometry is illustrative; no measured value is read off the render.

Schematic

Gravity-stable front

Recovery labels are the measured NBU corefloods from SPE-190183 Table 6.

Schematic on data

Pseudo-ternary construction

Compositions are schematic; the marked pressure is the Eagle Ford MMP of 2,132 psig.

Schematic

PublicationsPrimary sources

Adel, I.A., Tovar, F.D., and Schechter, D.S. 2016. Fast-Slim Tube: A Reliable and Rapid Technique for the Laboratory Determination of MMP in CO₂–Light Crude Oil Systems. SPE-179673-MS, SPE Improved Oil Recovery Conference, Tulsa, Oklahoma, 11–13 April. DOI

Adel, I.A., Tovar, F.D., Zhang, F., and Schechter, D.S. 2018. The Impact of MMP on Recovery Factor During CO₂–EOR in Unconventional Liquid Reservoirs. SPE-191752-MS, SPE Annual Technical Conference and Exhibition, Dallas, Texas, 24–26 September. DOI

Adel, I.A., Zhang, F., Bhatnagar, N., and Schechter, D.S. 2018. The Impact of Gas-Assisted Gravity Drainage on Operating Pressure in a Miscible CO₂ Flood. SPE-190183-MS, SPE Improved Oil Recovery Conference, Tulsa, Oklahoma, 14–18 April. DOI

Measured basis

Slim-tube MMP determination

Two least-squares branches are fitted to the measured recovery points on either side of the published MMP. Their intersection is recomputed when the system changes.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

System selection—

CO₂–oil system

Published MMP

—

psig

Computed intersection

—

psig

Deviation

—

computed − published

Measured slim-tube recovery and the two straight-line fits used for the breakover intersection.

Measured points and fit split

Pressure (psig)	Recovery (% OOIP)	Fit branch

immiscible branch (below the published MMP) miscible branch (at or above it)

Fast-slim-tube protocolSPE-179673

The 20-ft slim tube returned MMP in under two weeks, about one third of the 80-ft duration, across five CO₂–crude systems that included North Burbank Unit and Oklahoma/Texas Panhandle oils. Validity requires the tube to host the mixing zone and the displacement velocity to remain slow enough for transverse dispersion to suppress viscous fingering.

Core response

Huff-n-puff pressure response

Each Eagle Ford point is an experiment-level ultimate recovery. The Wolfcamp A marker is a separate rock–oil system and is not joined to the Eagle Ford series.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

Eagle Ford CO₂ huff-n-puff ultimate recovery across the measured pressure span. The open square is Wolfcamp A · ultimate · JPSE Fig. 11 and is labeled 5,000 psi (as published, JPSE).SPE-191752 Figure 9 / SPE-191502, as tabulated in the source figure; Wolfcamp A: JPSE 2021 Fig. 11 and Table 4.

Pressure records

System	Pressure	Ultimate RF (% OOIP)	Source

highest measured Eagle Ford RF first measurable production

Orientation

Gravity drainage

Recovery is compared at the same pressures for horizontal and vertical coreflood orientations. The MMP remains on the numeric pressure axis.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

System selectionSPE-190183 Table 6

Coreflood system

Horizontal and vertical recovery at three measured pressures; the bars are offset by pressure so the MMP remains on the same numeric axis.SPE-190183 Table 6.

Orientation deltaVertical − horizontal

Pressure (psig)	Horizontal (% OOIP)	Vertical (% OOIP)	Delta (points)

Vertical gravity-stable displacement recovered 90.4% of OOIP at 1,100 psig where the horizontal flood recovered 33.5% — the gravity contribution exceeds the miscibility contribution below the MMP.

Cross-comparison

Published MMP range

The six published values are placed on a common pressure scale. No literature benchmark band is applied because the source papers do not specify one.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

Published minimum miscibility pressures for the six slim-tube systems.

System matrix

System	Temperature (°F)	MMP (psig)	Maximum measured RF (%)	Source

Em dash: temperature not reported in the source table.

Live computation

Operating-pressure planner

The selected pressure is classified against the published MMP. Recovery is interpolated only between adjacent measured points.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

HOW TO USE

Select one of the six CO₂–oil systems. Set the pressure with the slider, anywhere in the 500–6,000 psig interface range. Read the regime against that system's published MMP and the within-span linear interpolation, then export the controls and outputs or import a prior scenario file.

Reading the chart: the filled red series is the measured slim-tube curve and the open marker is the current selection; it disappears whenever the selected pressure falls outside the measured span, where no value is interpolated. The dashed vertical rule marks the published MMP for the selected system. Hover any point for values; drag to zoom; double-click to reset the view.

Scenario controls

CO₂–oil system

Operating pressure2,500 psig

500psig6,000

Regime

—

Slim-tube RF

—

% OOIP

Huff-n-puff RF

—

Eagle Ford only

Measured slim-tube curve with the current within-span selection shown as an open marker.

Chart data

Record	Pressure (psig)	RF (% OOIP)

current selection, interpolated between two measured points

Calculation basis

Model & equations

The page uses two fitted lines for breakover pressure and piecewise linear interpolation for within-span recovery estimates.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

Equations

(1) Least-squares line

m = [nS_xy − S_xS_y] / [nS_xx − (S_x)²]
b = (S_y − mS_x) / n
RF = mp + b

S_x and S_y are the sums of the n pressures x and recoveries y on one branch; S_xy and S_xx are the sums of the products xy and x². A separate line is fitted to measured points below and at or above the published MMP.

(2) Breakover intersection

p_MMP,fit = (b₂ − b₁) / (m₁ − m₂)

Subscript 1 is the immiscible branch and subscript 2 the miscible branch. The computed pressure is compared with the published MMP using 100 × (computed − published) / published. Where a branch holds exactly two measured points the line is an exact solve, not a regression, and the panel states the point count.

(3) Linear interpolation

RF(p) = RF₁ + (p − p₁)(RF₂ − RF₁) / (p₂ − p₁)

The equation is evaluated only when p lies between two measured pressures; outside that span the planner returns no value.

Constants and fixed inputsRead from the report engine

Constant	Value	Unit	Source

Regime classification uses each system's own published MMP, applied as a whole-psig threshold. The pressure-control bounds are an interface range, not a measured limit.

Assumptions and limits

Published MMP values define the immiscible and miscible point split used for the two least-squares fits.
Slim-tube and huff-n-puff interpolation is piecewise linear and is not evaluated outside the measured pressure span.
Slim-tube RF is an upper bound on core-scale huff-n-puff RF at the same pressure; the two are plotted separately and never mixed.
The pressure-control bounds and defaults are interface ranges, not data.
Pressure units follow each publication: psig for SPE records and psi for the JPSE record.
The gauge/absolute distinction (15 psi or less) is below the resolution of the reported values and is not reconciled.

Visualization

Core-scale displacement schematics

Two editorial section diagrams illustrate coreflood displacement and the front shapes associated with gravity-stable and horizontal displacement. Geometry is illustrative; the recovery labels on the second diagram are measured values.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

Coreflood displacement section

Gas enters from the inlet face. Time advances an illustrative displacement front; the slice control marks an axial location behind, within, or ahead of the mixing zone. Front and slice positions are geometric indices, not measured CT values.

t = 24 h Time, h YZ slice x/L

Gravity-stable vs unstable displacement

Recovery values are the measured NBU corefloods (SPE-190183 Table 6; MMP 1,373 psig). Vertical displacement holds a flat, stable front; horizontal displacement fingers and bypasses oil.

Front

Pseudo-ternary construction

Schematic pseudo-ternary at the selected operating pressure. Successive contacts walk the gas composition along the dew-point curve and the two-phase region contracts as pressure rises. Compositions are schematic; the marked pressure is the Eagle Ford MMP of 2,132 psig (SPE-179673).

Operating pressure, psig 2,500 psig

Pseudo-ternary construction of multi-contact miscibility; compositions are schematic.

Reference

Nomenclature

Symbols and abbreviations used in the figures and calculations.

Prepared by Imad A. Adel · Senior Petroleum Research Engineer, Chemical & Petroleum Engineering

Symbols

Symbol	Meaning	Unit
p	Pressure	psig or psi
p_MMP,fit	Breakover pressure from the two fitted branches	psig
m	Least-squares slope	% OOIP/psig
b	Least-squares intercept	% OOIP
n	Number of measured points on one branch	dimensionless
x	Pressure ordinate in the least-squares fit	psig
y	Recovery ordinate in the least-squares fit	% OOIP
S	Branch sum, subscripted by the quantity summed	varies
RF	Recovery factor	% OOIP
T	Temperature	°F

Abbreviations

Term	Meaning
CO₂	Carbon dioxide
GAGD	Gas-assisted gravity drainage
MMP	Minimum miscibility pressure
OOIP	Original oil in place
RF	Recovery factor

Does recovery stop improving at the MMP?

Slim-tube MMP

Huff-n-puff

Gravity drainage

Pressure planner

Slim-tube MMP determination

Huff-n-puff pressure response

Gravity drainage

Published MMP range

Operating-pressure planner

Model & equations

Core-scale displacement schematics

Coreflood displacement section

Gravity-stable vs unstable displacement

Pseudo-ternary construction

Nomenclature