U.S. SHALE BASINS MORE THAN JUST THE MARCELLUS AND UTICA Modified from Groundwater Protection Council, 2009
GENERALIZED GEOLOGIC COLUMN FOR WESTERN PA MARCELLUS SHALE UTICA SHALE About 3,500 feet
Modified from Piotrowski and Harper, 1979; and Harper and Abel, 1980 “THREE BELT” DISTRIBUTION OF THICK (>100 FEET) DEVONIAN SHALES IN PENNSYLVANIA GENESEO / BURKET
ORGANIC-RICH SHALE IS JUST SHALE WITH A LOT OF ORGANIC MATERIAL LOCKED UP IN THE MINERAL MATRIX
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 non- porous limestone 6.Overburden – buries reservoir under thousands of feet of rock CONVENTIONAL RESERVOIR
SANDSTONE : A TYPICAL CONVENTIONAL RESERVOIR ROCK
SAND GRAIN PORE THIN SECTION PHOTO OF POROUS SANDSTONE EMBEDDED IN BLUE EPOXY TO SHOW PORE SPACES PORE SAND GRAIN SAND GRAIN SCALE:
SHALE (UNCONVENTIONAL) RESERVOIR Source rock elements (organic compounds) remain in the shale Reservoir and seal are vastly different than those in conventional systems Porosity (total pore space) and permeability (interconnected pore space) are extremely limited Modified from Laughrey, 2009
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 SCALE: 40 Microns PORE
EXTENT OF DEVONIAN SHALES IN THE APPALACHIAN BASIN
THICKNESS AND EXTENT OF THE DEVONIAN SHALE INTERVAL IN THE NORTHERN APPALACHIAN BASIN Milici and Swezey, 2006 Extent of shales Line of thickness (feet)
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
Modified from Smith, 2011 Utica Shale Very little carbonate TOC 1 – 3% Point Pleasant Formation Interbedded limestone and shale Shale TOC up to 3%
Utica/ Pt. Pleasant Geneseo/Burket Marcellus
THIN SECTION PHOTOS OF THE UTICA SHALE FROM OHIO AND THE MARCELLUS SHALE FROM PENNSYLVANIA Scale bar = 0.5 mm UTICAMARCELLUS
SEM PHOTOS OF UTICA SHALE IN NEW YORK AND OHIO From Daniels and others, 2011 MICROPORES IN NEW YORK UTICA ORGANIC-RICH SHALE IN OHIO Organic-rich regions
PERMITTED, DRILLED, AND COMPLETED UTICA/POINT PLEASANT WELLS IN PENNSYLVANIA AS OF APRIL 6, 2012
Modified from Patchen and others, 2008 Source rock maturation status based on combined CAI to Ro regression equation (Hulver, 1997; Rowan, 2006)