mudloggers photos on Flickr

Kimberlite (modern fluvial clast) (creek at Chatham, Licking County, Ohio, USA) 3 by James St. John

4

(~7.4 centimeters across at its widest)

---------------------------------------------------------

Kimberlites and lamproites have tremendous economic importance because they are host rocks for gem-grade and industrial-grade diamonds. Kimberlites & lamproites are unusual igneous bodies having overall pipe-shaped geometries. Their mode of formation is only moderately understood because they have not been observed forming. Kimberlites & lamproites are known from scattered localities throughout the world - only some are significantly diamondiferous. Classic localities for diamonds are India and Brazil. Africa was also discovered to have many kimberlites and is world-famous for producing large numbers of diamonds. Other notable diamondiferous kimberlite-lamproite occurrences include Russia, China, northwestern Australia, and northwestern Canada.

Kimberlites are named for the town of Kimberley, South Africa. Several kimberlite pipes occur in the Kimberley area. Kimberlites have a gently tapering-downward, pipe-shaped cross-section. Lamproites have a cross-section more closely resembling that of a martini glass.

Seen here is Ohio's only known kimberlite sample. It's not from Ohio's bedrock, however - it's a modern fluvial clast, derived from a Pleistocene glacial till. The original kimberlite body was somewhere in Canada. Pleistocene glaciers eroded much of Canada's bedrock and delivered the debris to the northern parts of America, including about two-thirds of Ohio. Because this sample was not collected in-situ, additional specimens are unlikely to be found at the same site. Kimberlite is a rare rock in general.

Mantle xenoliths composed of peridotite (= an olivine-rich, ultramafic, intrusive igneous rock) are scattered throughout this specimen (click on the photo once or twice to zoom in; a small peridotite xenolith is present at left). No diamonds are visible at the surface.

If anyone is preparing to counter my above statement that this is Ohio's only known kimberlite with a citation to Baranoski et al. (2007), there's a tale there. Long story short - it was a practical joke gone horribly wrong.

Long story long - The Murray # 2-1875 was a petroleum well drilled in 1994 into the Dillon Falls Astrobleme northwest of Zanesville, Ohio. There were two stages of drilling: 1) into the structure, which dates to the Early or Middle Ordovician; and 2) almost to basement rocks. Several wells have been drilled into the sandstones that fill the inferred impact crater - some have produced natural gas. During the second stage of drilling, while penetrating Cambrian dolostones (= Copper Ridge Dolomite to Rome Dolomite succession), a geologist, as a joke, salted a well cuttings sample bag with dark-colored, crystalline-textured igneous rock chips. The intent was to mess with a couple of the other geologists at the well site. The mudlogger washed the sample and presented it to the geologists, who were shocked. Different interpretations were quickly formulated - a sill? a kimberlite? This resulted in much commotion and laughter. The sample bag was tossed into a pile of other bags. All the sample bags were eventually sent to the Ohio Geological Survey. The geologists forgot all about it - just a small practical joke. Until 2007 - it was published! Baranoski et al. (2007) described the occurrence of an odd igneous body in this well - possibly a kimberlite. They did note the complete lack of evidence for the inferred igneous body on the wire-line log. Oops. One of the original geologists at the well site contacted the Survey upon learning of the publication. They were informed that it was a practical joke - all in fun. It was never intended to mislead anyone, let along the Ohio Geological Survey. Despite being told about the situation, the publication has not been retracted or corrected (as far as I know). Everyone gets fooled sometimes. I have. But boo-boos need to be corrected. This is a major boo-boo.

Locality: loose clast from a modern gravel bar (derived from Upper Pleistocene glacial till) along a south-flowing tributary of Clear Fork, just north of Chatham Road bridge, western side of the town of Chatham, northwestern Newton Township, northern Licking County, central Ohio, USA

--------------------------------------------

Reference cited:

Baranoski et al. (2007) - Deep gas well encounters ultramafic kimberlite-like material in the Sauk Sequence of southeastern Ohio, USA. Geosphere 3: 177-183.

Kimberlite (modern fluvial clast) (creek at Chatham, Licking County, Ohio, USA) 4 by James St. John

1 1

(~7.4 centimeters across at its widest)

---------------------------------------------------------

Kimberlites and lamproites have tremendous economic importance because they are host rocks for gem-grade and industrial-grade diamonds. Kimberlites & lamproites are unusual igneous bodies having overall pipe-shaped geometries. Their mode of formation is only moderately understood because they have not been observed forming. Kimberlites & lamproites are known from scattered localities throughout the world - only some are significantly diamondiferous. Classic localities for diamonds are India and Brazil. Africa was also discovered to have many kimberlites and is world-famous for producing large numbers of diamonds. Other notable diamondiferous kimberlite-lamproite occurrences include Russia, China, northwestern Australia, and northwestern Canada.

Kimberlites are named for the town of Kimberley, South Africa. Several kimberlite pipes occur in the Kimberley area. Kimberlites have a gently tapering-downward, pipe-shaped cross-section. Lamproites have a cross-section more closely resembling that of a martini glass.

Seen here is Ohio's only known kimberlite sample. It's not from Ohio's bedrock, however - it's a modern fluvial clast, derived from a Pleistocene glacial till. The original kimberlite body was somewhere in Canada. Pleistocene glaciers eroded much of Canada's bedrock and delivered the debris to the northern parts of America, including about two-thirds of Ohio. Because this sample was not collected in-situ, additional specimens are unlikely to be found at the same site. Kimberlite is a rare rock in general.

Mantle xenoliths composed of peridotite (= an olivine-rich, ultramafic, intrusive igneous rock) are scattered throughout this specimen (click on the photo once or twice to zoom in; about a dozen small peridotite xenoliths are present in this view). No diamonds are visible at the surface.

If anyone is preparing to counter my above statement that this is Ohio's only known kimberlite with a citation to Baranoski et al. (2007), there's a tale there. Long story short - it was a practical joke gone horribly wrong.

Long story long - The Murray # 2-1875 was a petroleum well drilled in 1994 into the Dillon Falls Astrobleme northwest of Zanesville, Ohio. There were two stages of drilling: 1) into the structure, which dates to the Early or Middle Ordovician; and 2) almost to basement rocks. Several wells have been drilled into the sandstones that fill the inferred impact crater - some have produced natural gas. During the second stage of drilling, while penetrating Cambrian dolostones (= Copper Ridge Dolomite to Rome Dolomite succession), a geologist, as a joke, salted a well cuttings sample bag with dark-colored, crystalline-textured igneous rock chips. The intent was to mess with a couple of the other geologists at the well site. The mudlogger washed the sample and presented it to the geologists, who were shocked. Different interpretations were quickly formulated - a sill? a kimberlite? This resulted in much commotion and laughter. The sample bag was tossed into a pile of other bags. All the sample bags were eventually sent to the Ohio Geological Survey. The geologists forgot all about it - just a small practical joke. Until 2007 - it was published! Baranoski et al. (2007) described the occurrence of an odd igneous body in this well - possibly a kimberlite. They did note the complete lack of evidence for the inferred igneous body on the wire-line log. Oops. One of the original geologists at the well site contacted the Survey upon learning of the publication. They were informed that it was a practical joke - all in fun. It was never intended to mislead anyone, let along the Ohio Geological Survey. Despite being told about the situation, the publication has not been retracted or corrected (as far as I know). Everyone gets fooled sometimes. I have. But boo-boos need to be corrected. This is a major boo-boo.

Locality: loose clast from a modern gravel bar (derived from Upper Pleistocene glacial till) along a south-flowing tributary of Clear Fork, just north of Chatham Road bridge, western side of the town of Chatham, northwestern Newton Township, northern Licking County, central Ohio, USA

--------------------------------------------

Reference cited:

Baranoski et al. (2007) - Deep gas well encounters ultramafic kimberlite-like material in the Sauk Sequence of southeastern Ohio, USA. Geosphere 3: 177-183.

Kimberlite (modern fluvial clast) (creek at Chatham, Licking County, Ohio, USA) 1 by James St. John

2 1

(~7.4 centimeters across at its widest)

---------------------------------------------------------

Kimberlites and lamproites have tremendous economic importance because they are host rocks for gem-grade and industrial-grade diamonds. Kimberlites & lamproites are unusual igneous bodies having overall pipe-shaped geometries. Their mode of formation is only moderately understood because they have not been observed forming. Kimberlites & lamproites are known from scattered localities throughout the world - only some are significantly diamondiferous. Classic localities for diamonds are India and Brazil. Africa was also discovered to have many kimberlites and is world-famous for producing large numbers of diamonds. Other notable diamondiferous kimberlite-lamproite occurrences include Russia, China, northwestern Australia, and northwestern Canada.

Kimberlites are named for the town of Kimberley, South Africa. Several kimberlite pipes occur in the Kimberley area. Kimberlites have a gently tapering-downward, pipe-shaped cross-section. Lamproites have a cross-section more closely resembling that of a martini glass.

Seen here is Ohio's only known kimberlite sample. It's not from Ohio's bedrock, however - it's a modern fluvial clast, derived from a Pleistocene glacial till. The original kimberlite body was somewhere in Canada. Pleistocene glaciers eroded much of Canada's bedrock and delivered the debris to the northern parts of America, including about two-thirds of Ohio. Because this sample was not collected in-situ, additional specimens are unlikely to be found at the same site. Kimberlite is a rare rock in general.

Mantle xenoliths composed of peridotite (= an olivine-rich, ultramafic, intrusive igneous rock) are scattered throughout this specimen (click on the photo once or twice to zoom in; a small peridotite xenolith is below & to the right of the picture's center). No diamonds are visible at the surface.

If anyone is preparing to counter my above statement that this is Ohio's only known kimberlite with a citation to Baranoski et al. (2007), there's a tale there. Long story short - it was a practical joke gone horribly wrong.

Long story long - The Murray # 2-1875 was a petroleum well drilled in 1994 into the Dillon Falls Astrobleme northwest of Zanesville, Ohio. There were two stages of drilling: 1) into the structure, which dates to the Early or Middle Ordovician; and 2) almost to basement rocks. Several wells have been drilled into the sandstones that fill the inferred impact crater - some have produced natural gas. During the second stage of drilling, while penetrating Cambrian dolostones (= Copper Ridge Dolomite to Rome Dolomite succession), a geologist, as a joke, salted a well cuttings sample bag with dark-colored, crystalline-textured igneous rock chips. The intent was to mess with a couple of the other geologists at the well site. The mudlogger washed the sample and presented it to the geologists, who were shocked. Different interpretations were quickly formulated - a sill? a kimberlite? This resulted in much commotion and laughter. The sample bag was tossed into a pile of other bags. All the sample bags were eventually sent to the Ohio Geological Survey. The geologists forgot all about it - just a small practical joke. Until 2007 - it was published! Baranoski et al. (2007) described the occurrence of an odd igneous body in this well - possibly a kimberlite. They did note the complete lack of evidence for the inferred igneous body on the wire-line log. Oops. One of the original geologists at the well site contacted the Survey upon learning of the publication. They were informed that it was a practical joke - all in fun. It was never intended to mislead anyone, let along the Ohio Geological Survey. Despite being told about the situation, the publication has not been retracted or corrected (as far as I know). Everyone gets fooled sometimes. I have. But boo-boos need to be corrected. This is a major boo-boo.

Locality: loose clast from a modern gravel bar (derived from Upper Pleistocene glacial till) along a south-flowing tributary of Clear Fork, just north of Chatham Road bridge, western side of the town of Chatham, northwestern Newton Township, northern Licking County, central Ohio, USA

--------------------------------------------

Reference cited:

Baranoski et al. (2007) - Deep gas well encounters ultramafic kimberlite-like material in the Sauk Sequence of southeastern Ohio, USA. Geosphere 3: 177-183.

Kimberlite (modern fluvial clast) (creek at Chatham, Licking County, Ohio, USA) 2 by James St. John

(~7.4 centimeters across at its widest)

---------------------------------------------------------

Kimberlites and lamproites have tremendous economic importance because they are host rocks for gem-grade and industrial-grade diamonds. Kimberlites & lamproites are unusual igneous bodies having overall pipe-shaped geometries. Their mode of formation is only moderately understood because they have not been observed forming. Kimberlites & lamproites are known from scattered localities throughout the world - only some are significantly diamondiferous. Classic localities for diamonds are India and Brazil. Africa was also discovered to have many kimberlites and is world-famous for producing large numbers of diamonds. Other notable diamondiferous kimberlite-lamproite occurrences include Russia, China, northwestern Australia, and northwestern Canada.

Kimberlites are named for the town of Kimberley, South Africa. Several kimberlite pipes occur in the Kimberley area. Kimberlites have a gently tapering-downward, pipe-shaped cross-section. Lamproites have a cross-section more closely resembling that of a martini glass.

Seen here is Ohio's only known kimberlite sample. It's not from Ohio's bedrock, however - it's a modern fluvial clast, derived from a Pleistocene glacial till. The original kimberlite body was somewhere in Canada. Pleistocene glaciers eroded much of Canada's bedrock and delivered the debris to the northern parts of America, including about two-thirds of Ohio. Because this sample was not collected in-situ, additional specimens are unlikely to be found at the same site. Kimberlite is a rare rock in general.

Mantle xenoliths composed of peridotite (= an olivine-rich, ultramafic, intrusive igneous rock) are scattered throughout this specimen (click on the photo once or twice to zoom in; a small peridotite xenolith is below & to the right of the picture's center). No diamonds are visible at the surface.

If anyone is preparing to counter my above statement that this is Ohio's only known kimberlite with a citation to Baranoski et al. (2007), there's a tale there. Long story short - it was a practical joke gone horribly wrong.

Long story long - The Murray # 2-1875 was a petroleum well drilled in 1994 into the Dillon Falls Astrobleme northwest of Zanesville, Ohio. There were two stages of drilling: 1) into the structure, which dates to the Early or Middle Ordovician; and 2) almost to basement rocks. Several wells have been drilled into the sandstones that fill the inferred impact crater - some have produced natural gas. During the second stage of drilling, while penetrating Cambrian dolostones (= Copper Ridge Dolomite to Rome Dolomite succession), a geologist, as a joke, salted a well cuttings sample bag with dark-colored, crystalline-textured igneous rock chips. The intent was to mess with a couple of the other geologists at the well site. The mudlogger washed the sample and presented it to the geologists, who were shocked. Different interpretations were quickly formulated - a sill? a kimberlite? This resulted in much commotion and laughter. The sample bag was tossed into a pile of other bags. All the sample bags were eventually sent to the Ohio Geological Survey. The geologists forgot all about it - just a small practical joke. Until 2007 - it was published! Baranoski et al. (2007) described the occurrence of an odd igneous body in this well - possibly a kimberlite. They did note the complete lack of evidence for the inferred igneous body on the wire-line log. Oops. One of the original geologists at the well site contacted the Survey upon learning of the publication. They were informed that it was a practical joke - all in fun. It was never intended to mislead anyone, let along the Ohio Geological Survey. Despite being told about the situation, the publication has not been retracted or corrected (as far as I know). Everyone gets fooled sometimes. I have. But boo-boos need to be corrected. This is a major boo-boo.

Locality: loose clast from a modern gravel bar (derived from Upper Pleistocene glacial till) along a south-flowing tributary of Clear Fork, just north of Chatham Road bridge, western side of the town of Chatham, northwestern Newton Township, northern Licking County, central Ohio, USA

--------------------------------------------

Reference cited:

Baranoski et al. (2007) - Deep gas well encounters ultramafic kimberlite-like material in the Sauk Sequence of southeastern Ohio, USA. Geosphere 3: 177-183.

Mudlogging trailer at VanWinkle Unit # 1 petroleum well (west of Granville, Ohio, USA) by James St. John

Mudlogging trailer at an actively drilling petroleum well in Licking County, Ohio, USA. (February 2018) (site access generously provided by Gary Sitler for geoscience education purposes)

During the late 1800s, Ohio was the # 1 petroleum exporter on Earth. This is definitely not the case anymore! Despite this, Ohio today still has economic concentrations of oil and natural gas.

Ohio has three significant petroleum occurrences:

1) Trenton Limestone (upper Middle Ordovician) of northwestern Ohio.

2) Clinton Sandstone (Lower Silurian) of eastern Ohio.

3) Knox Group (Beekmantown Dolomite-Rose Run Sandstone-Copper Ridge/Trempealeau Dolomite) (Upper Cambrian to ?lowermost Ordovician) in the eastern ~half of Ohio.

Of these three petroleum systems, the Knox Group generally requires the deepest drilling. Most Knox Group drilling in Ohio targets the Rose Run Sandstone, an interbedded quartzose sandstone-dolostone unit of Late Cambrian age.

The well shown above is being actively drilled (as of February 2018). It was targeting a paleotopographic high at the Knox Unconformity and hoping to encounter petroleum in porous dolostone.

During drilling, most wellsites have an onsite geologist, called a mudlogger. This is a mudlogging trailer, which serves as a temporary home for the wellsite geologist. Some mudlogging companies work shifts (different geologists are here at different times of the day), while others do not (the geologist works and sleeps here continuously until the well is done). The geologist keeps track of the drilling rate and the stratigraphic unit being drilled, monitors how much natural gas is coming out of the well, examines and describes rock chip samples, and prepares a written log.

Update: as of fall 2018, this well was producing petroleum from the Upper Trempealeau Dolomite (also known as the Copper Ridge Dolomite). Petroleum is coming from porous dolostones below the Knox Unconformity. The Knox is a megasequence boundary (Sloss sequence boundary) that separates the Sauk Megasequence below from the Tippecanoe Megasequence above.

The following are formation picks for this well (the numbers are from the completion record filed with the Ohio Division of Natural Resources, Division of Oil and Gas Resources):

375 feet depth = top of the Berea Sandstone (lowermost Devonian)

1190 feet depth = top of the "Big Lime" (= Devonian and Silurian carbonate succession, including the Delaware Limestone, Columbus Limestone, and Silurian dolostones)

1992 feet depth = top of the "Packer Shell" (= Middle Silurian Dayton Formation equivalent)

3324 feet depth = Trenton Limestone (upper Middle Ordovician, sensu traditio; lower Upper Ordovician, sensu novo)

3855 feet depth = Gull River Limestone (Middle Ordovician)

3920 feet depth = Knox Unconformity with Trempealeau Dolomite below (Upper Cambrian)

Locality: VanWinkle Unit # 1 well (permit # 34089261880000) (804' SL, 1794' EL, northeastern quarter of township), west of Granville, St. Albans Township, Licking County, Ohio, USA (40° 04' 55.13" North latitude, 82° 34' 38.00" West longitude)

----------------------

See info. at:

en.wikipedia.org/wiki/Drilling_rig

and

gis.ohiodnr.gov/MapViewer/WellSummaryCard.asp?api=3408926...

Mudlogging trailer at Hendren Century Farms # 2 petroleum well (north of Johnstown, Ohio, USA) 5 by James St. John

Mudlogging trailer at an actively drilling petroleum well in Licking County, Ohio, USA. (October 2016) (site access generously provided by Gary Sitler for geoscience education purposes)

During the late 1800s, Ohio was the # 1 petroleum exporter on Earth. This is definitely not the case anymore! Despite this, Ohio today still has economic concentrations of oil and natural gas.

Ohio has three significant petroleum occurrences:

1) Trenton Limestone (upper Middle Ordovician) of northwestern Ohio.

2) Clinton Sandstone (Lower Silurian) of eastern Ohio.

3) Knox Group (Beekmantown Dolomite-Rose Run Sandstone-Copper Ridge/Trempealeau Dolomite) (Upper Cambrian to ?lowermost Ordovician) in the eastern ~half of Ohio.

Of these three petroleum systems, the Knox Group generally requires the deepest drilling. Most Knox Group drilling in Ohio targets the Rose Run Sandstone, an interbedded quartzose sandstone-dolostone unit of Late Cambrian age.

The active wellsite shown above (as of late October 2016) was targeting a paleotopographic high at the Knox Unconformity and hoping to encounter petroleum in porous dolostone. During this visit, the rig was drilling at a depth between 3,300 and 3,400 feet below the surface.

During drilling, most wellsites have an onsite geologist, called a mudlogger. This photo shows equipment in a mudlogging trailer, which serves as a temporary home for the wellsite geologist. Some mudlogging companies work shifts (different geologists are here at different times of the day), while others do not (the geologist works and sleeps here continuously until the well is done). The geologist keeps track of the drilling rate and the stratigraphic unit being drilled, monitors how much natural gas is coming out of the well, examines and describes rock chip samples, and prepares a written log.

The microscope is used to closely examine rock samples (which come out of the well as broken chips or finely-pulverized granules and dust). The enclosed metal box with the green viewing port has an interior ultraviolet (UV) black light and is used for examining petroleum content in rock samples - hydrocarbons glow under black light.

Update: as of spring 2017, this well was making 100 to 125 MCF a day (= 100 to 125 thousand cubic feet of natural gas) and 10 barrels of oil per day. The producing horizon is in the Upper Cambrian Copper Ridge Dolomite (also known as the Trempealeau Dolomite). Petroleum is coming from porous dolostones below the Knox Unconformity. The Knox is a megasequence boundary (Sloss sequence boundary) that separates the Sauk Megasequence below from the Tippecanoe Megasequence above.

The following are formation picks for this well (the numbers are from the completion record filed with the Ohio Division of Natural Resources, Division of Oil and Gas Resources):

430 feet depth = top of the Berea Sandstone (lowermost Devonian)

1182 feet depth = top of the "Big Lime" (= Devonian and Silurian carbonate succession, including the Delaware Limestone, Columbus Limestone, and Silurian dolostones)

1940 feet depth = top of the "Packer Shell" (= Middle Silurian Dayton Formation equivalent)

3252 feet depth = Trenton Limestone (upper Middle Ordovician, sensu traditio; lower Upper Ordovician, sensu novo)

3790 feet depth = Gull River Limestone (Middle Ordovician)

3830 feet depth = Knox Unconformity with Trempealeau Dolomite below (Upper Cambrian)

According to State of Ohio records, this well has produced the following:

2017 - 38 barrels of oil, 12,660 MCF of natural gas (= thousands of cubic feet of natural gas), 516 barrels of brine (= salt water)

2018 - 59 barrels of oil, 2828 MCF of natural gas, 175 barrels of brine

2019 - 144 MCF of natural gas

2020 - 21 MCF of natural gas, 130 barrels of brine

2021 - no production

Locality: Hendren Century Farms # 2 well (permit # 34089261840000) (2026' SL, 1526' WL, Lot 10, 4th Quarter of Township), north of Johnstown, Hartford Township, northwestern Licking County, Ohio, USA

----------------------

See info. at:

gis.ohiodnr.gov/MapViewer/WellSummaryCard.asp?api=3408926...

Blow line & valve for samples at Hendren Century Farms # 2 petroleum well (north of Johnstown, Ohio, USA) by James St. John

Actively drilling petroleum well in Licking County, Ohio, USA. (October 2016) (site access generously provided by Gary Sitler for geoscience education purposes)

During the late 1800s, Ohio was the # 1 petroleum exporter on Earth. This is definitely not the case anymore! Despite this, Ohio today still has economic concentrations of oil and natural gas.

Ohio has three significant petroleum occurrences:

1) Trenton Limestone (upper Middle Ordovician) of northwestern Ohio.

2) Clinton Sandstone (Lower Silurian) of eastern Ohio.

3) Knox Group (Beekmantown Dolomite-Rose Run Sandstone-Copper Ridge/Trempealeau Dolomite) (Upper Cambrian to ?lowermost Ordovician) in the eastern ~half of Ohio.

Of these three petroleum systems, the Knox Group generally requires the deepest drilling. Most Knox Group drilling in Ohio targets the Rose Run Sandstone, an interbedded quartzose sandstone-dolostone unit of Late Cambrian age.

The well shown above is being actively drilled (as of late October 2016). It was targeting a paleotopographic high at the Knox Unconformity and hoping to encounter petroleum in porous dolostone. During this visit, the rig was drilling at a depth between 3,300 and 3,400 feet below the surface.

This photo shows part of the blow line, through which rock chips are continuously and forcefully ejected from the hole and into a nearby tarp-lined pit. The valve seen here is used for collecting samples for the well-site geologist ("mudlogger"). Sample quality varies from decent-sized rock chips to very fine-grained dust (awful) to rich in cavings (= spalled-off rock chips from the walls of the hole significantly above the actual drilling horizon) (also awful). Rock samples are described and logged by the geologist. The Ohio Geological Survey occasionally requests that samples be kept for them.

Update: as of spring 2017, this well was making 100 to 125 MCF a day (= 100 to 125 thousand cubic feet of natural gas) and 10 barrels of oil per day. The producing horizon is in the Upper Cambrian Copper Ridge Dolomite (also known as the Trempealeau Dolomite). Petroleum is coming from porous dolostones below the Knox Unconformity. The Knox is a megasequence boundary (Sloss sequence boundary) that separates the Sauk Megasequence below from the Tippecanoe Megasequence above.

The following are formation picks for this well (the numbers are from the completion record filed with the Ohio Division of Natural Resources, Division of Oil and Gas Resources):

430 feet depth = top of the Berea Sandstone (lowermost Devonian)

1182 feet depth = top of the "Big Lime" (= Devonian and Silurian carbonate succession, including the Delaware Limestone, Columbus Limestone, and Silurian dolostones)

1940 feet depth = top of the "Packer Shell" (= Middle Silurian Dayton Formation equivalent)

3252 feet depth = Trenton Limestone (upper Middle Ordovician, sensu traditio; lower Upper Ordovician, sensu novo)

3790 feet depth = Gull River Limestone (Middle Ordovician)

3830 feet depth = Knox Unconformity with Trempealeau Dolomite below (Upper Cambrian)

According to State of Ohio records, this well has produced the following:

2017 - 38 barrels of oil, 12,660 MCF of natural gas (= thousands of cubic feet of natural gas), 516 barrels of brine (= salt water)

2018 - 59 barrels of oil, 2828 MCF of natural gas, 175 barrels of brine

2019 - 144 MCF of natural gas

2020 - 21 MCF of natural gas, 130 barrels of brine

2021 - no production

Locality: Hendren Century Farms # 2 well (permit # 34089261840000) (2026' SL, 1526' WL, Lot 10, 4th Quarter of Township), north of Johnstown, Hartford Township, northwestern Licking County, Ohio, USA

----------------------

See info. at:

gis.ohiodnr.gov/MapViewer/WellSummaryCard.asp?api=3408926...

Mudlogging trailer at Hendren Century Farms # 2 petroleum well (north of Johnstown, Ohio, USA) 4 by James St. John

Mudlogging trailer at an actively drilling petroleum well in Licking County, Ohio, USA. (October 2016) (site access generously provided by Gary Sitler for geoscience education purposes)

During the late 1800s, Ohio was the # 1 petroleum exporter on Earth. This is definitely not the case anymore! Despite this, Ohio today still has economic concentrations of oil and natural gas.

Ohio has three significant petroleum occurrences:

1) Trenton Limestone (upper Middle Ordovician) of northwestern Ohio.

2) Clinton Sandstone (Lower Silurian) of eastern Ohio.

3) Knox Group (Beekmantown Dolomite-Rose Run Sandstone-Copper Ridge/Trempealeau Dolomite) (Upper Cambrian to ?lowermost Ordovician) in the eastern ~half of Ohio.

Of these three petroleum systems, the Knox Group generally requires the deepest drilling. Most Knox Group drilling in Ohio targets the Rose Run Sandstone, an interbedded quartzose sandstone-dolostone unit of Late Cambrian age.

The active wellsite shown above (as of late October 2016) was targeting a paleotopographic high at the Knox Unconformity and hoping to encounter petroleum in porous dolostone. During this visit, the rig was drilling at a depth between 3,300 and 3,400 feet below the surface.

During drilling, most wellsites have an onsite geologist, called a mudlogger. This photo shows equipment in a mudlogging trailer, which serves as a temporary home for the wellsite geologist. Some mudlogging companies work shifts (different geologists are here at different times of the day), while others do not (the geologist works and sleeps here continuously until the well is done). The geologist keeps track of the drilling rate and the stratigraphic unit being drilled, monitors how much natural gas is coming out of the well, examines and describes rock chip samples, and prepares a written log.

This piece of equipment is a gas chromatograph, which determines the type of natural gases coming out of the well (methane, butane, propane, etc.).

Update: as of spring 2017, this well was making 100 to 125 MCF a day (= 100 to 125 thousand cubic feet of natural gas) and 10 barrels of oil per day. The producing horizon is in the Upper Cambrian Copper Ridge Dolomite (also known as the Trempealeau Dolomite). Petroleum is coming from porous dolostones below the Knox Unconformity. The Knox is a megasequence boundary (Sloss sequence boundary) that separates the Sauk Megasequence below from the Tippecanoe Megasequence above.

The following are formation picks for this well (the numbers are from the completion record filed with the Ohio Division of Natural Resources, Division of Oil and Gas Resources):

430 feet depth = top of the Berea Sandstone (lowermost Devonian)

1182 feet depth = top of the "Big Lime" (= Devonian and Silurian carbonate succession, including the Delaware Limestone, Columbus Limestone, and Silurian dolostones)

1940 feet depth = top of the "Packer Shell" (= Middle Silurian Dayton Formation equivalent)

3252 feet depth = Trenton Limestone (upper Middle Ordovician, sensu traditio; lower Upper Ordovician, sensu novo)

3790 feet depth = Gull River Limestone (Middle Ordovician)

3830 feet depth = Knox Unconformity with Trempealeau Dolomite below (Upper Cambrian)

According to State of Ohio records, this well has produced the following:

2017 - 38 barrels of oil, 12,660 MCF of natural gas (= thousands of cubic feet of natural gas), 516 barrels of brine (= salt water)

2018 - 59 barrels of oil, 2828 MCF of natural gas, 175 barrels of brine

2019 - 144 MCF of natural gas

2020 - 21 MCF of natural gas, 130 barrels of brine

2021 - no production

Locality: Hendren Century Farms # 2 well (permit # 34089261840000) (2026' SL, 1526' WL, Lot 10, 4th Quarter of Township), north of Johnstown, Hartford Township, northwestern Licking County, Ohio, USA

----------------------

See info. at:

gis.ohiodnr.gov/MapViewer/WellSummaryCard.asp?api=3408926...

Mudlogging trailer at Hendren Century Farms # 2 petroleum well (north of Johnstown, Ohio, USA) 1 by James St. John

2