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24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 1 0f 58
CAN MUDLOGGING
SHOWS BE QUANTIFIED?
Bill Donovan, PE Donovan Brothers Incorporated
Automated Mudlogging Systems
Our Corporate Motto
“WE DON’T PASS GAS”
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 2 0f 58
Can Mudlogging Shows be Quantified?
• Field study results
• Definitions and theory
• Resource comparison
• Mudlogging gas content
• Factors influencing mudlogging
• Calibrating the system
OVERVIEW
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Can Mudlogging Shows be Quantified?
PRB CBM Field Study Results 55 wells with Mudlog GC (green)
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Common form of volumetric gas in place for shale and coal
G = gas in place (MCF)
A = drainage area (acres)
H = thickness (feet)
ρb = bulk density (gm/cc)
GC = gas content (scf/ton)
Can Mudlogging Shows be Quantified?
PRB CBM Field Study Results
GCHA3597.1G b
PRB CBM Field Study Results
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Can Mudlogging Shows be Quantified?
bHA3597.1GGC
Back calculated gas content is based on cumulative production and/or estimated ultimate recovery (EUR) G is cumulative production or EUR A is the spacing unit H and ρb are from logs
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Can Mudlogging Shows be Quantified?
PRB CBM Field Study Results
55 wells with Mudlog GC (green)
Cumulative Production GC (blue)
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Can Mudlogging Shows be Quantified?
PRB CBM Field Study Results
55 wells with Mudlog GC (green)
Cumulative Production GC (blue)
Estimated Ultimate Recovery GC (red)
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Can Mudlogging Shows be Quantified?
PRB CBM Field Study Results
55 wells with Mudlog GC (green)
Cumulative Production GC (blue)
Estimated Ultimate Recovery GC (red)
Isotherm Estimated GC (purple)
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Can Mudlogging Shows be Quantified?
OHIO
WESTMORELAND
WEST
VIRGINIA MARYLAND
PENNSYLVANIA
Marcellus Shale HZ Well Results Ty Taylor’s
Clemson
MS Thesis
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Can Mudlogging Shows be Quantified?
MAHANTANGO SH
MARCELLUS
SH
Marcellus Shale HZ Well Results
Ty Taylor’s
Clemson
MS Thesis
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Can Mudlogging Shows be Quantified?
Marcellus Shale HZ Well Results Ty Taylor’s
Clemson
MS Thesis
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Can Mudlogging Shows be Quantified?
0
100
200
300
400
500
600
1 2 3 4 5 6 7 8 9 10 11 12
TG
(g
as
un
its)
Well
TG Mean
TG (TRAP) Mean
NORMALIZE MUDLOGS
ON MATAHANGO SH
Marcellus Shale HZ Well Results
Ty Taylor’s
Clemson
MS Thesis
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Can Mudlogging Shows be Quantified?
R² = 0.87
400,000
800,000
1,200,000
1,600,000
2,000,000
0 2,000,000 4,000,000 6,000,000
18
Mo
nth
Pro
du
ctio
n
(MC
F)
TG(TRAP) sum (gas units)
Marcellus Shale HZ Well Results
Ty Taylor’s
Clemson
MS Thesis
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© Donovan Brothers Inc. Automated Mudlogging Systems SM Slide ‹#› 0f 58
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• Define mudlogging
• Define mudlogging gas measurements
Percent Equivalent Methane in Air
(% EMA) and “Units EMA”
• Explain why mudlogging is effective
• Compare resources for different
reservoirs
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Can Mudlogging Shows be Quantified?
Definitions and Theory
Define mudlogging and a mudlog
• A mudlog is a record over time of rig functions, gas and cuttings
• The basic mud log records: 1) drilling rate, 2) gas measured at the mudlogging unit and 3) cutting properties such as lithology and the presence of oil
• A mudlog presents the above properties and others as a function of depth
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Can Mudlogging Shows be Quantified?
Definitions and Theory
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Can Mudlogging Shows be Quantified?
• EQUIVALENT METHANE IN AIR (% EMA) is a measure of methane in air at the measurement point (the mudlogging unit) expressed as a percent of methane in the air sample or expressed differently as10,000 parts per million methane by volume
• Calibrated and measured at the mudlogging unit, the whole system is not calibrated
• Although related to mudlogging gas content, % EMA is not a measure of gas in the formation or drilling mud
• Other hydrocarbon gases are presented as methane
• Typically 100 “Units EMA” equals 1% EMA
Definitions and Theory
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Definitions and Theory Can Mudlogging Shows be Quantified?
MUDLOGGING IS EFFECTIVE BECAUSE:
•Gas is measured at the surface under STP
•Gas is insoluble in water and drilling mud
•Gas expands as it travels to the surface
•Mudlogging is independent of theories and models
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MUDLOGGING IS EFFECTIVE BECAUSE:
•Gas is measured at the surface under STP
•Gas is insoluble in water and drilling mud
•Gas expands as it travels to the surface
•Mudlogging is independent of theories and models
Can Mudlogging Shows be Quantified?
Definitions and Theory
Surface gas volume for one
cubic foot of gas or gas
saturated water at certain depths
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Can Mudlogging Shows be Quantified?
MUDLOGGING IS
EFFECTIVE BECAUSE:
•Gas is measured at the
surface at STP
•Gas is insoluble in
water and drilling mud
•Gas expands as it
travels to the surface
•Mudlogging is
independent of theories
and models
Definitions and Theory
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Can Mudlogging Shows be Quantified?
MUDLOGGING IS EFFECTIVE BECAUSE:
•Gas is measured at the surface at STP
•Gas is insoluble in water and drilling mud
•Gas expands as it travels to the surface
•Mudlogging is independent of theories and models
Definitions and Theory
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Can Mudlogging Shows be Quantified?
Fruitland Coal
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Can Mudlogging Shows be Quantified?
3’ Perfed
Pictured Cliff SS
Perfed
3’
1,124’-
1,127’
Foam fraced
w/18K#
10-20 sand
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Can Mudlogging Shows be Quantified?
The next five slide present the amount of gas liberated and brought to the surface for coal, shale, oil and gas reservoirs.
The and colored bars to the left show and values relative to the
reservoirs.
All slides have the same format and vertical scales
Again the conclusion reached is that both conventional and unconventional hydrocarbon reservoirs liberate gas in quantities significantly higher than reservoirs containing water
Resource Comparison
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Can Mudlogging Shows be Quantified?
Resource Comparison
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Can Mudlogging Shows be Quantified?
Resource Comparison
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Can Mudlogging Shows be Quantified?
Resource Comparison
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Can Mudlogging Shows be Quantified?
Resource Comparison
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Can Mudlogging Shows be Quantified?
Resource Comparison
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Can Mudlogging Shows be Quantified?
The requirements to calibrate mudlogging show
are:
1) The cubic feet of acetylene generate per
pound of calcium carbide (yield)
2) Calibrate the mudlogging gas sensor with
both acetylene and methane
3) The peak gas reading of a carbide lag
using a measured amount of carbide
Mudlogging Gas Content Methodology
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Can Mudlogging Shows be Quantified?
The requirements to calibrate mudlogging show
are:
4) The gas units during a mudlog show
5) The bit diameter
6) The drilling rate during a mudlog show
7) Simple mathematical computations to
calculate gas liberated per minute and
rock volume drilled per minute
Mudlogging Gas Content Methodology
• A measured amount of Calcium Carbide reacts with
water to make known amount of acetylene gas: CaC2 +
H20 = C2H2 +CaO
• Before mudlogging a calibration using both acetylene
and methane establishes a relationship between the
gases for the mudlogging unit’s gas sensors
• Before and after the zone of interest is drilled a known
amount of Calcium Carbide (acetylene) is put in the drill
string during connections and pumped to the surface.
The peak gas value is recorded
• Using this data, a gas show in units EMA can be
converted to SCF of gas liberated while drilling
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Can Mudlogging Shows be Quantified?
Mudlogging Gas Content Methodology
• The hole volume is known, therefore, SCF/formation bulk
volume (ft3) can be calculated along with BCF/section or
MCF/acre-foot . These are the standard measures of
used in volumetric reservoir calculations
• If the formation density is known, gas content (SCF/Ton)
can be calculated
• If Bg or Bo, the gas expansion factor or the oil shrinkage
factor, is known reservoir hydrocarbon foot (SoPhieH or
HCF) along with Bvg or reservoir gas porosity can be
calculated
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Can Mudlogging Shows be Quantified?
Mudlogging Gas Content Methodology
• 0.5 cup of calcium carbide yields
1.268 SCF acetylene
• 125 “units” of acetylene reads 250
units EMA in the mudlogging unit
• 0.5 cup of calcium carbide in a
connection before the zone yields
200 “units” of acetylene
• Calculate a conversion factor from
the above data and Avogadro's Law
• Conversion factor
0.01268 SCF CH4 /1 UNIT EMA
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Can Mudlogging Shows be Quantified?
Mudlogging Gas Content Methodology
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Can Mudlogging Shows be Quantified?
Mudlogging Gas Content Methodology
Calculate a conversion factor from data on the
last slide and Avogadro's Law
22
422
22
2
2
22
1
1
125
250
250
5.0
5.0
268.1
HCSCF
CHSCF
EMAUnits
HCUnits
HCUnits
CaCCUPS
CaCCUPS
HCSCF
From Carbide Manufacturer
From Carbide Lag
From Different %’s of CH4 and
C2H2 Gas Tested on Sensors
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 37 0f 58
Can Mudlogging Shows be Quantified?
Mudlogging Gas Content Methodology
Calculate a conversion factor from data on
the last slide and Avogadro's Law.
Conversion factor =
Conversion factor =
0.01268 SCF CH4 /1 UNIT EMA
4
22
4
4
22
22
22
2
22
4
2
22
%25.1
%25.1
125
%25.1
%25.1
250
250
5.0
268.1
268.1
5.0
268.1
CH
HC
CHEMA
CH
HC
HCUnits
HCUnits
CaCCUPS
HCSCF
CHSCF
CaCCUPS
HCSCF
• Gas reading in the zone 570
UNITS EMA/minute
• Calculate gas liberated per
minute in the zone by
multiplying gas reading by the
conversion factor
• 570 UNITS EMA /minute X
0.01268 SCF/UNIT EMA=
7.23 SCF/Minute
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 38 0f 58
Can Mudlogging Shows be Quantified?
Mudlogging Gas Content Methodology
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 39 0f 58
Can Mudlogging Shows be Quantified?
• Penetration rate in the zone is
0.5 minutes/foot
• Hole diameter is 8.5 inches
• Calculate the hole bulk volume
(BV) drilled per minute
• Hole Volume/Minute =
0.78813 BV Cubic Feet/Minute
Mudlogging Gas Content Methodology
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 40 0f 58
Can Mudlogging Shows be Quantified?
• Divide the gas liberated per
minute by the hole volume
drilled per minute
• 7.23(SCF/Minute) /
0.78813(BV CF/Minute) =
9.17 SCF/BV CF
• Conversion factors can be
used to calculate BCF/Section
foot or MCF/Acre foot
Mudlogging Gas Content Methodology
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 41 0f 58
Can Mudlogging Shows be Quantified?
• Zone density is 1.4 gms/cc
• Convert hole BV CF to Tons by
using density
• Gas content 210 SCF/Ton
• Zone depth 1,000’, Bg = 36.4
• Convert SCF to Reservoir CF
by using Bg
• Bulk Volume Mudlog Gas
0.25 CF/BV or 25%
Mudlogging Gas Content Methodology
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 42 0f 58
Can Mudlogging Shows be Quantified?
The factors which influence mudlogging can be grouped into two general categories:
• Deterministic factors
(hole size, drilling rate, etc.)
• Indeterminate factors
(flushing, background gas, surface losses, gas trap performance)
Carbide calibration accounts for all factors
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 43 0f 58
Can Mudlogging Shows be Quantified?
Deterministic factors affecting mudlog gas are:
• Gas in the formation
• Hole size
• Drilling rate
• Mud pump rate
• Gas expansion
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 44 0f 58
Can Mudlogging Shows be Quantified?
If all other factors are equal, doubling
the gas in the formation doubles the
gas show
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 45 0f 58
Can Mudlogging Shows be Quantified?
If all other factors are equal, doubling the hole diameter, quadruples the gas show
Factors Influencing Mudlogging
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Can Mudlogging Shows be Quantified?
If all other factors are equal, doubling the drilling rate, doubles the gas show
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 47 0f 58
Can Mudlogging Shows be Quantified?
If all other factors are equal, doubling mud pump rate, decreased by one half the gas show
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 48 0f 58
Can Mudlogging Shows be Quantified?
If all other factors are equal, doubling
the depth of the formation doubles the
gas show in conventional reservoirs
Factors Influencing Mudlogging
Indeterminate factors are:
• Recycled gas (minor)
• Contaminated mud (seldom)
• Formation flushing (minor)
• Loses while drilling (seldom)
• A kick while drilling (seldom)
• Uphole kicks or loses (seldom)
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 49 0f 58
Can Mudlogging Shows be Quantified?
Factors Influencing Mudlogging
More indeterminate factors are:
• Cuttings not fully releasing gas (minor)
• Surface losses (major)
• Gas trap design (major)
• Temperature (major)
• Wind (seldom)
• Miscalibrated sensors (seldom)
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Can Mudlogging Shows be Quantified?
Factors Influencing Mudlogging
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Can Mudlogging Shows be Quantified?
Gas trap efficiency and measurement stability is the largest cause of mudlogging error. See the SPE, Williams and Ewing article.
GAS IN THE MUD GA
S A
T T
HE
MU
DL
OG
GIN
G U
NIT
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 52 0f 58
Can Mudlogging Shows be Quantified?
“Improved Methods for Samplings Gas
and Drill Cuttings”, Williams and Ewing,
SPE FE, June 1989
Factors Influencing Mudlogging
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Can Mudlogging Shows be Quantified?
GRI
Gas Measurements During
Mud Logging Operations
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 54 0f 58
Can Mudlogging Shows be Quantified?
EFFECT OF TEMPERATURE ON THE
SOLUBILITY OF GAS IN WATER
0
2
4
6
8
10
0 50 100 150 200 250
TEMPERATURE (DEGREE F)
SO
LU
BIL
ITY
AT
TE
MP
ER
AT
UR
E/S
OL
UB
ILIT
Y
AT
180 D
EG
RE
ES
FA
HR
EN
HE
IT
CH4 @ T/ CH4 @ 180 F
C2H2 @ T/ C2H2 @ 180 F
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 55 0f 58
Can Mudlogging Shows be Quantified?
GRI
Gas Measurements During
Mud Logging Operations
Factors Influencing Mudlogging
24/January/201
4
© Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 56 0f 58
Notice all the potential errors:
• 100 units of gas in the mud could read as high as 200 units or as low as 3 units due to gas trap design
• Gas losses as much as 40% due to loss in the flow line
• Gas losses as much as 50% due to wind
• A six fold change in methane solubility in water from 40ºF to 180ºF
All of these losses can be normalized or compensated for by the use of calibrated carbide lagging. The next slide shows that acetylene behaves like methane over a wide range of conditions. If carbide lag results are consistent, it indicates good quality mudlogging
Can Mudlogging Shows be Quantified?
Factors Influencing Mudlogging
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 57 0f 58
Can Mudlogging Shows be Quantified?
SOLUBILITY OF GAS IN WATER
0
10
20
30
40
50
60
70
80
0 50 100 150 200 250
TEMPERATURE (DEGREE F)
SO
LU
BIL
ITY
RA
TIO
(C
2H
2/C
H4)
RATIO
Calibrating the System
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 58 0f 58
Mudlogging is an effective evaluation tool
If you have questions or comments contact me
Bill Donovan
(303) 794-7470
www.mudlogger.com
Can Mudlogging Shows be Quantified?
24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 59 0f 58
Can Mudlogging Shows be Quantified?
School for
Gifted
MUDLOGGERS
After
Gary
Larson
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Can Mudlogging Shows be Quantified?
Walt
Kelly