Mudlogging and Geosteering gg g g Appalachian Horizontal Oil and

Mudlogging and Geosteering gg g
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Appalachian Horizontal Oil and Gas Plays
By: Will Gilliam Who is RGC?
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Formed January 2013, Focused on providing quality well site geologists for the growing horizontal drilling market in the Appalachian Basin.
the Appalachian Basin.
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Headquartered in Morehead, KY
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12 Geologist
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Experience in conventional and unconventional reservoirs, Experience
in conventional and unconventional reservoirs
geologic mapping, horizontal drilling, mudlogging, and geosteering.
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Primary area of operation is the Appalachian Basin: St. P
i
f
ti i th A
l hi B i St
Louis, Ft. Payne, Berea, Cleveland, Chattanooga, Lower Huron, Marcellus, Utica.
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We also work elsewhere: Wolfcamp, Eagle Ford, Barnett, Austin Chalk.
Selecting Horizontal Targets
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Target Selection varies by reservoir
conventional vs. unconventional
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Carbonate Reservoirs Low Gamma
Low Bulk Density, Indicates porosity
y,
p
y
‐Biogenic, bryzoans, ooids
‐ Dolomitic, vugs
‐ density limestone ~ 2.71 g/cc ‐ density dolomite ~ 2.87 g.cc
PE
‐ dolomite ~ 3.05 – 3.14
‐ Limestone ~ 4.90 – 5.08
High Resistivity
High
Resistivity
‐ Indicates hydrocarbon
Gas Effect
‐ Density/Neutron Crossover
‐ Neutron Porosity underestimated due to presence of gas
Courtesy of Vinland Energy
Selecting Horizontal Targets
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Target Selection varies by reservoir
conventional vs. unconventional
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Tight Sandstone/Siltstone Reservoir
Low Gamma
Low Bulk Density y
‐ Due to presence of Pore space density sandstone ~ 2.65 g/cc
High Resistivity
‐ Due to the presence of hydrocarbons
PE ‐ Sandstone ~ 1.66‐1.70
Gas Effect Crossover
‐ Density/Neutron Crossover
‐ Neutron Porosity underestimated due to presence of gas
presence of gas
Modified from uky.edu/kgs
Selecting Horizontal Targets
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Unconventional Reservoirs
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Sh
l G R
i
Shale Gas Reservoirs Hot Gamma
‐ GR 400 ‐ 500 API
Low Bulk Density y
‐ Due to presence of Kerogen and hydrocarbons
density organics 0.50 ‐1.8 g/cc
density shale 1.8 – 2.9 g/cc
PE
‐ Shale ~ 3.0 ‐5.0
High Resistivity
‐ Due to presence of clays and/or
Due to presence of clays and/or
hydrocarbons
Modified from uky.edu/kgs
Well Planning
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The Key to a successful horizontal well is a solid well plan. Structure Contour Map Top of the Berea ‐
First step is to create subsurface map of the reservoir target surface (target centerline).
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Determine regional dip, and calculate dip along the wellbore azimuth. ‐
When ready to make a final horizontal well plan determine
When ready to make a final horizontal well plan, determine coordinates for the surface location, KOP, landing point, and TD TVD of the target centerline.
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Provide target data to the directional company as well as regional dip and dip azimuth of the target centerline to formulate a final drill plan.
TD
Surface Location
Well Planning Continued
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Well Plans can vary depending on type of reservoir conventional vs. unconventional.
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Conventional reservoirs should be planned in the direction of maximum porosity, and above the oil/water contact.
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Shale gas wells should be planned perpendicular to regional dip in order to maximize the regional fracture trend in the Appalachian Basin (~ SW to NE in Southeastern Kentucky).
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Avoid areas with large displacement faults, crossing faults results in loss of pay formation. ‐
Identify water zones above reservoir, design casing plan accordingly.
Mudlogging
Vertical Mudlog
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Mudlogging Services are provided from job site office type trailers. ‐
Mudlogs can be compiled in either vertical or horizontal format
and include sample photographs in plain light or black light or videos. ‐
Geologist examines cutting for:
G
l i
i
i f
Lithology Oil Show
Porosity
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AT KOP, samples are collected to make sure the driller is off the plug, in the curve samples are collected at intervals determined by the client in the curve and lateral
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In the curve formation tops are identified and compared In
the curve formation tops are identified and compared
against the geologic prognosis to determine if changes are needed to the landing point. ‐
In horizontal drilling the mudloggers main focus is the keep the operator in target In lateral the mudlogger observes cutting
operator in target. In lateral the mudlogger observes cutting for changes in formation and if it occurs we notify the company man and geologist.
Horizontal Cross Section Mudlog
Mudlogging Continued
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Morning and Evening Mudlogging Reports are emailed from the well site to the operating company. ‐
Reports include an updated mudlog.
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These report highlight the days drilling activity, amount of footage drilled in the last 12 or 24 hours, average ROP, drilling fluid and mud weight, oil or gas shows, and peaks on the gas chromatograph.
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Also included is a photo of the last sample collected before report time and current drill depth.
Gas Detection
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Gas Detection key in horizontal drilling.
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TTakes the guess work out of frac port placement and k th
k t ff
t l
t d
spacing.
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iBall Bloodhound Gas Detection with Chromatograph.
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Detects: Methane, Ethane, Propane, Butane, nano‐
butane, iso‐butane from flow line, gives good first look at gas composition.
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Gas Peaks likely indicate fractures. y
f
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WITSML capable, can be viewed remotely, in real‐time by the operator.
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Provides real time oil indicator calculations, Shell Method P
id
l ti
il i di t
l l ti
Sh ll M th d
(heavy/light).
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Somewhat limited on soap and water.
Geosteering
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Geosteering is the process by which to determine the wellbore position within the stratigraphic target using incoming gamma and survey data compared to an offset compared to an offset
incoming gamma and survey data
well log.
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Service can be provided remotely or from the field. ‐
Correlations to determine the stratigraphic distance from target surface is calculated using incoming survey and gamma data and compared to an adjacent type log or logs.
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Service allows operators to maintain maximum target accuracy. Example shows 96.8% in the pay zone.
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Compilation of multiple data tracks in cross section view show the operator ROP, Gamma, and Total Gas along the wellbore path.
wellbore path. Geosteering Continued
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In some instances faulting or unplanned changes in dip can occur. ‐
RGC can track these changes and calculate the distance existing between the target centerline and the wellbore.
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Example to the right shows scenario where the target ended up lower and dip being steeper than originally p
p
g
p
g
y
anticipated in the well plan.
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Also you can see the well went outside of the target and drilled into the top of the lower formation
drilled into the top of the lower formation.
Geosteering Continued
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Reports are sent on a survey by survey basis, or at intervals dictated by the clients preference.
Good Morning,
Latest Survey Data:
MD: 9184
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Geosteering reports include the latest directional survey, the relative stratigraphic distance from the latest survey point to the target top, center, and base, and the apparent bedding dip
apparent bedding dip. Reports also include comments on how well the gamma is correlating with the type log. INC: 83.7
AZM: 132
Formation Tops
TVD: 2639.34
EST TVD
VS: 6745.91
Distance From Survey
Sunbury
2485.3
Berea
2514.8
154.1' Above Survey Point
124.6' Above Survey Point
Cleveland
2544.8
94.6' Above Survey Point
Target Top
2558.8
80.6' Above Survey Point
Target Base
2591.3
48.1' Above Survey Point
2665 3
2665.3
25 9' Below Survey Point
25.9
Below Survey Point
Three Lick Bed
Three Lick Bed
Current Operation: Drilling Ahead
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The stratigraphic distance and bedding dip calculations provide data for the directional driller to make adjusts to the wellbore trajectory on‐the‐fly
The survey point is ~ 64.3 ft. below the Target Center.
Formation dip is 89.6°
Summary Data:
The depth of the Target Center has moved up ~1.4 ft. from 2576.53 to 2575.1 ft. TVD.
Gamma correlation with the type log is tentative.
If you have any questions or comments, please do not hesitate to call or email me.
Respectfully submitted,
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Using this data RGC can project the target interval at specific distances (VS) ahead of the bit (i.e. 250’, 500’)
Geologist: Thomas Nelson
Takeaways
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Horizontal wells require proper target selection.
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Well log data coupled with mudlog oil or gas show data key in picking a productive reservoir target
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Mapping of the target centerline provides subsurface data points in which to plan the horizontal well path. ‐
Mudlogging evaluates drill cutting for oil and gas shows and lithology. Also identifies formation tops and marker beds.
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Geosteering provides quantitative interpretation of gamma and LWD data to determine true stratigraphic position of the wellbore within the reservoir interval, maximizing productivity and profits.
Thank You
KY‐ Section SPE!
Special Thanks to :
EQT
Vinland Energy