Transcript Geology of PA`s Shale Gas Plays-

MORE THAN JUST THE MARCELLUS AND UTICA
U.S. SHALE BASINS
Modified from Groundwater Protection Council, 2009
MARCELLUS SHALE
About 3,500 feet
GENERALIZED
GEOLOGIC
COLUMN FOR
WESTERN PA
UTICA SHALE
“THREE BELT” DISTRIBUTION OF THICK (>100 FEET)
DEVONIAN SHALES IN PENNSYLVANIA
Modified from
Piotrowski and
Harper, 1979; and
Harper and Abel,
1980
ORGANIC-RICH
SHALE IS JUST
SHALE WITH A LOT OF
ORGANIC MATERIAL
LOCKED UP IN THE
MINERAL MATRIX
CONVENTIONAL RESERVOIR
1. Source rock (organic-rich
shale) – generation and
expulsion
2. Migration – from source to
reservoir
3. Reservoir rock (sandstone
or limestone) – holds
petroleum in internal pore
space
4. Trap (e.g. unconformity or
fault) – keeps petroleum in
reservoir
5. Seal – impervious rock
such as shale or nonporous limestone
6. Overburden – buries
reservoir under thousands
of feet of rock
SANDSTONE:
A TYPICAL CONVENTIONAL
RESERVOIR ROCK
THIN SECTION PHOTO OF POROUS SANDSTONE
EMBEDDED IN BLUE EPOXY TO SHOW PORE SPACES
PORE
SAND
GRAIN
SAND
GRAIN
SAND
GRAIN
PORE
SCALE:
SHALE (UNCONVENTIONAL) RESERVOIR
 Source rock elements
(organic compounds)
remain in the shale
 Reservoir and seal are
vastly different than
those in conventional
systems
Modified from Laughrey, 2009
 Porosity (total pore
space) and
permeability
(interconnected pore
space) are extremely
limited
TYPICAL ORGANIC-RICH SHALE
THIN SECTION PHOTO OF ORGANIC-RICH SHALE
SHOWING LITTLE OR NO POROSITY
ALGAL CYSTS
SCALE:
SCANNING ELECTRON MICROSCOPE (SEM)
PHOTO OF THE MARCELLUS SHALE
PORE
PORE
PORE
PORE
PORE
SCALE:
40 Microns
EXTENT OF DEVONIAN
SHALES IN THE
APPALACHIAN BASIN
THICKNESS AND
EXTENT OF THE
DEVONIAN SHALE
INTERVAL IN THE
NORTHERN
APPALACHIAN BASIN
Extent of shales
Line of thickness
(feet)
Milici and Swezey, 2006
DRILLING DEPTH TO THE BASE OF THE MARCELLUS SHALE
From Boswell, 1996
APPROXIMATE ORIENTATIONS OF J1 AND J2 JOINT SETS
IN THE MARCELLUS SHALE OF PENNSYLVANIA
Natural
hydraulic
fractures
Tectonic
fractures
WAYS TO DRILL AND FRAC A
MARCELLUS WELL
Green arrows indicate the orientation of J1
fractures and blue ovals indicate the gas
drainage area in a Marcellus well:
A – a vertical well will produce a relatively
smaller amount of gas because the borehole may
or may not intersect a limited number of J1
joints. Even fracing the well will have a limited
effect.
B – a horizontal well drilled parallel with the J1
joint set will produce a relatively smaller amount
of gas for the same reason as in A.
C – a horizontal well drilled perpendicular to the
J1 joint set will intersect numerous J1 joints, and
thus have the ability to drain a much larger area.
MOST OPERATORS IN PENNSYLVANIA ARE DRILLING HORIZONTAL
MARCELLUS WELLS ORIENTED PERPENDICULAR TO THE J1 JOINT SET
Natural
hydraulic
fractures
THE MARCELLUS PLAY IN THE APPALACHIAN BASIN
Modified from
Durham, 2011
MARCELLUS WELLS IN PENNSYLVANIA
Permits Issued and Wells Drilled as of
November 30, 2011
EXTENT AND DRILLING DEPTH OF THE UTICA SHALE
Modified from Geology.com
Utica Shale
Very little carbonate
TOC 1 – 3%
Point Pleasant Formation
Interbedded limestone
and shale
Shale TOC up to 3%
Modified from Smith, 2011
Geneseo/Burket
Marcellus
Utica/
Pt. Pleasant
THIN SECTION PHOTOS OF THE UTICA SHALE FROM OHIO
AND THE MARCELLUS SHALE FROM PENNSYLVANIA
UTICA
Scale bar = 0.5 mm
MARCELLUS
SEM PHOTOS OF UTICA SHALE IN NEW YORK AND OHIO
MICROPORES IN
NEW YORK UTICA
ORGANIC-RICH SHALE IN OHIO
Organic-rich
regions
From Daniels and others, 2011
PERMITTED, DRILLED, AND COMPLETED
UTICA/POINT PLEASANT WELLS IN PENNSYLVANIA
AS OF APRIL 6, 2012
Source rock maturation status based on combined CAI to Ro
regression equation (Hulver, 1997; Rowan, 2006)
Modified from Patchen and others, 2008