Using geophysical and remote sensing techniques to ...

Open-File Oil and Gas Report 14–01.0

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USING GEOPHYSICAL AND REMOTE SENSING TECHNIQUES TO EVALUATE DEEP GEOLOGIC FORMATIONS IN INDIANA COUNTY, PENNSYLVANIA GEOLOGIC STRUCTURE FROM 2D SEISMIC DATA -------------------------------------

by Kristin M. Carter Pennsylvania Geological Survey

Katherine W. Schmid Pennsylvania Geological Survey

William Harbert The University of Pittsburgh

Jay B. Parrish The Pennsylvania State University

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PENNSYLVANIA GEOLOGICAL SURVEY FOURTH SERIES HARRISBURG

2014

OPEN-FILE REPORT DISCLAIMER No Warranty

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The user shall save the Commonwealth of Pennsylvania harmless from any suits, claims, or actions arising out of the use of or any defect in the open-file report or accompanying documentation. The Commonwealth of Pennsylvania assumes no legal liability for the accuracy, completeness, or usefulness of the open-file report and accompanying documentation. In no event shall the Commonwealth of Pennsylvania have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic or geologic data. Use and Access Constraints

Not for commercial resale. This open-file report is not designed for use as a primary regulatory tool in permitting and siting decisions. It is public information and, as such, it may be used as a reference source and may be interpreted by organizations, agencies, units of government, or others based on needs; however, each user is responsible for the appropriate application of the data. Federal, state, or local regulatory bodies are not to reassign to the Bureau of Topographic and Geologic Survey any authority for the decisions they make using this report. The maps included in this report are not meant for site-specific analysis. Users are not to misrepresent the maps by presenting them at scales (i.e., larger, more detailed scales) for which it was not intended, nor to imply that presentation at such scales is approved by the Bureau of Topographic and Geologic Survey.

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Material from this report may be published if credit is given to the Pennsylvania Geological Survey This report has been prepared in accordance with the open-file reporting standards of the Bureau of Topographic and Geologic Survey.

This open-file report can be obtained through the Bureau of Topographic and Geologic Survey website at www.dcnr.state.pa.us/topogeo Suggested citation: Carter, K.M., Schmid, K.W., Harbert, William, and Parrish, J.B., 2014, Using geophysical and remote sensing techniques to evaluate deep geologic formations in Indiana County, Pennsylvania—Geologic structure from 2D seismic data: Pennsylvania Geological Survey, 4th ser., Open-File Report OFOG 14–01.0, 8 p., Portable Document Format (PDF). ii

CONTENTS CONTENTS ................................................................................................................................... iii Figures.................................................................................................................................... iii Tables ..................................................................................................................................... iii Plates ...................................................................................................................................... iii EXECUTIVE SUMMARY ............................................................................................................ 1 INTRODUCTION AND PURPOSE .............................................................................................. 2 SEISMIC SURVEY METHODS ................................................................................................... 3 SEISMIC CORRELATIONS ......................................................................................................... 4 MAPPING THE ONONDAGA LIMESTONE .............................................................................. 6 ACKNOWLEDGMENTS .............................................................................................................. 8 REFERENCES CITED ................................................................................................................... 8

Figures Figure 1. Figure 2. Figure 3. Figure 4.

Case study site location map, Indiana County, Pennsylvania. ....................................... 2 Interpreted faults and regional fold axes for the case study site location. ...................... 3 Subsurface stratigraphic units of Indiana County, Pennsylvania (not to scale). ............ 5 Berringer well synthetic seismic trace. ........................................................................... 7

Tables Table 1. Data Processing Sequence (modified from Vogel et al., 2010). ...................................... 4

Plates Plate 1. Structure Contours on the Top of the Onondaga Limestone. ........................................... 9

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USING GEOPHYSICAL AND REMOTE SENSING TECHNIQUES TO EVALUATE DEEP GEOLOGIC FORMATIONS IN INDIANA COUNTY, PENNSYLVANIA GEOLOGIC STRUCTURE FROM 2D SEISMIC DATA Kristin M. Carter Katherine W. Schmid

Pennsylvania Geological Survey

William Harbert

The University of Pittsburgh

Jay B. Parrish

The Pennsylvania State University

EXECUTIVE SUMMARY gas emissions) are particularly prevalent; and second, to illustrate the use of geophysical and remote sensing techniques as a means to characterize deep geologic structure when publicly available data sets are limited. The case study location (Figure 1) spans several municipalities in southwestern Indiana County, including Armstrong, Black Lick, Center, Conemaugh, and Young townships. Between May and October 2009, BTGS participated in and managed the collection of two-dimensional (2D) seismic reflection data by ARM Geophysics, oversaw the collection and interpretation of various remote sensing data gathered by contractors, and extracted oil and gas well data for this Indiana County case study site from the Pennsylvania Internet Record Imaging System/Wells Information System (PA*IRIS/WIS). This series of open-file reports, entitled Using Geophysical and Remote Sensing Techniques to Evaluate Deep Geologic Formations in Indiana County, Pennsylvania, publishes the technical data sets generated for this project and cites relevant findings and interpretations about the case study location, as appropriate.

Act 129 of 2008 required the Pennsylvania Department of Conservation and Natural Resources (DCNR) to conduct a series of studies related to geologic carbon dioxide (CO2) sequestration in the Commonwealth. In accordance with Section 2815 of Act 129, the DCNR Bureau of Topographic and Geologic Survey (BTGS) prepared an initial study of suitable geologic formations for the location of a state CO2 sequestration network that the Commonwealth might establish on stateowned lands or lands on which the Commonwealth had acquired the rights to store CO2. That report, entitled Geologic Carbon Sequestration Opportunities in Pennsylvania, was initially published in May 2009, updated for technical content shortly thereafter, and published in revised format in August 2009 (DCNR, 2009). As an accompaniment to the geological assessment provided in the August 2009 report, BTGS completed a reconnaissancelevel evaluation for a site in western Pennsylvania. This case study was intended to address two issues: first, to improve our understanding of the Commonwealth’s subsurface geology in this area of western Pennsylvania, where coal-fired power plants (a major contributor to regional greenhouse 1

sensing data can be manipulated to resolve subsurface geologic structure. Subsequent open-file reports associated with the Indiana County site will include the following data sets and reports: 1) raw 2D seismic data – collected under the supervision of ARM Geophysics (Hershey, PA); 2) processed 2D seismic data – prepared under the supervision of ARM; 3) oil and gas well header and formation tops data – gathered by BTGS from PA*IRIS/WIS; 4) aeromagnetic survey results – prepared by Wintermoon Geotechnologies, Inc. (Denver, CO); 5) gravity data – prepared by Lafayette College (Easton, PA); and 6) fracture trace analysis – conducted by the Pennsylvania State University (State College, PA).

INTRODUCTION AND PURPOSE This digital open-file report is the first in a series of seven reports entitled Using Geophysical and Remote Sensing Techniques to Evaluate Deep Geologic Formations in Indiana County, Pennsylvania, and is associated with the reconnaissance-level evaluation of a case study site in southwestern Indiana County, Pennsylvania (Figure 1). The current report, subtitled Geologic Structure from 2D Seismic Data, presents relevant information regarding the 2D seismic survey project conducted by ARM Geophysics (ARM) under contract to BTGS (as reported in Vogel et al., 2010), and describes how we used this information to generate a geologic structure map on top of the Middle Devonian Onondaga Limestone in southwestern Indiana County. The purpose of this particular open-file release is twofold: (1) present the subsurface stratigraphic framework that relates to this and future reports in this open-file series; and (2) illustrate, by example, how remote

Figure 1. Case study site location map, Indiana County, Pennsylvania.

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strike (Figure 1). ARM refined the locations for these lines after performing a site reconnaissance to minimize the impacts of topography, buildings, utilities, and other logistical attributes on the quality of the seismic data. Where seismic data acquisition lines were at least 55 feet (ft) [16.8 meters (m)] from buildings, utilities, or other obstructions, source locations were placed every 220 ft (67 m) and receivers were placed every 110 ft (33.5 m). Approximately one mile of source points was lost along Line 102 between McIntyre and Coal Run, however, because of a high-pressure gas line not identified during the initial survey. The final locations of the processed seismic survey interpretation lines are shown in green on Figure 2.

SEISMIC SURVEY METHODS BTGS and ARM worked together to design the seismic line layout for this case study. BTGS planned three lines over the Jacksonville anticline, near the town of Jacksonville in Indiana County (see red lines in Figure 1). This faulted northeast-trending anticline has long been associated with oil and gas production. It is approximately 60 miles (mi) [96.6 kilometers (km)] long and 6.8 mi (10.9 km) wide, extending from Indiana County south into Westmoreland County (Faill, 2011). The first two seismic lines, 101 and 102, were oriented approximately parallel to geological dip, and cross the third line, 103, which is approximately parallel to geologic

Figure 2. Interpreted faults and regional fold axes for the case study site location.

The three 2D seismic surveys were conducted with the assistance of AOA

Geophysics, Inc. (Houston, TX) using an accelerated weight drop seismic source 3

known as the AXIS system. A seismic source walk-away test was performed prior to data acquisition to determine approximate data collection parameters. The seismic data for these three lines were collected from August 14, 2009 through August 31, 2009 to provide data to depths in excess of 12,000 ft (3,636 m). The data were processed using conventional 2D seismic processing methods, following the sequence listed in

Table 1. The common depth point (CDP) locations were generated in the crooked line geometry processing step. These CDP locations represent the actual location of the subsurface seismic data. Because of the significant amount of noise encountered during data acquisition, two passes of automatic surface consistent statistics (step 7) and noise attenuation (step 8) were applied to remove noise and increase the signal-to-noise ratio.

Table 1. Data Processing Sequence (modified from Vogel et al., 2010).

Step Activity 1 Reformat, vertical stack 2 Crooked line geometry 3 4

Trace edit Refraction statics, datum 1,350 ft

5 6 7

Surface consistent deconvolution Spectral balance Two passes of automatic surface consistent statics

8 9

Noise attenuation Dip moveout

10 11

Stack Migration

12 13

FX deconvolution Time variant filter 0.0 – 2.0 seconds 15-60 Hertz 2.5 – 4.0 seconds 15-45 Hertz

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AGC = 400 milliseconds

Result Seismic trace length adjusted Data spatially adjusted to account for curves in roads (nonlinear acquisition path) Seismic traces with excess noise or no data eliminated Data adjusted vertically to compensate for topographic elevation changes and shallow subsurface velocity variations Noise filtering based on source and receiver characteristics Frequency content of trace data equalized Second method used to vertically adjust data to compensate for topographic elevation changes and shallow subsurface velocity variations Removal of cultural noise from data Trace data adjusted for subsurface velocity effects prior to stacking Traces summed together to improve signal-to-noise ratio Stacked data spatially repositioned based on subsurface velocities Stacked data filtered to remove noise Frequency content of trace data limited to ranges indicated below 15 to 60 Hertz filter applied to traces in 0.0 to 2.0 second interval (0 to 2,000 milliseconds) 15 to 45 Hertz filter applied to traces in 0.0 to 2.0 second interval (0 to 2,000 milliseconds) Trace amplitudes balanced

local to the area. As oil and gas wells have been drilled in Indiana County to produce from a number of formations, the subsurface stratigraphy is well known here (Figure 3). Next, ARM converted these data to two-way time values using the stacking velocities from Line 101. Using these time-value data, ARM interpreted five stratigraphic horizons

SEISMIC CORRELATIONS After processing, ARM spatially correlated the seismic data along Lines 101, 102 and 103 using a step-wise approach. First, ARM obtained formation top and depth data interpreted by BTGS using geophysical logs from oil and gas wells 4

on each of the three seismic interpretation lines (see Vogel et al., 2010 – Appendix N in particular – for more on ARM’s correlations). Based on this analysis, the 2D seismic survey successfully penetrated rocks of Pennsylvanian through Middle Silurian age (see Figure 3) and a maximum depth of approximately 12,500 ft (3,810 m). ARM correlated the following stratigraphic horizons as part of their work: Horizon 1: Top of the Upper Devonian Elk Group [3,450 to 3,800 ft (1,052 to 1,158 m) depth]: This group is primarily composed of sandstone and shale, and includes oil and gas reservoirs throughout the study area. Horizon 2: Top of the Upper Devonian Brallier Formation: [4,900 to 5,300 ft (1,494 to 1,615 m) depth]: The Brallier Formation primarily consists of siltstone and shale, and produces oil and gas in parts of western Indiana County. Faults that show displacement in the Upper Silurian Salina Group and Middle Devonian Tully Limestone are interpreted to diminish in this formation. Horizon 3: Top of the Middle Devonian Tully Limestone: [6,300 to 6,600 ft (1,920 to 2,012 m) depth]: This limestone unit is a prominent stratigraphic marker bed at the top of the Hamilton Group, and that which BTGS uses to differentiate between shallow and deep petroleum production in Pennsylvania. Horizon 4: Top of the Upper Silurian Salina Group: [9,500 to 10,000 ft (2,896 to 3,048 m) depth]: This group includes salt, anhydrite, dolostone, and shale. Tectonically induced salt and anhydrite mobility from this horizon is the cause of the majority of faulting and structural deformation observed in the overlying Upper and Middle Devonian strata in this area.

Figure 3. Subsurface stratigraphic units of Indiana County, Pennsylvania (not to scale).

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Horizon 5: Silurian décollement surface: [10,950 to 11,400 ft (3,338 to 3,475 m) depth]: This detachment structure is interpreted by ARM to be situated near the top of the Middle Silurian Lockport Dolomite.

time, velocity, and depth maps to the top of the Onondaga Limestone in PETRASeis®. To assist with our identification of formation tops, we calculated synthetic seismic traces, where appropriate well log information was available, to compare with ARM’s seismic reflection cross sections. The Berringer well (Permit No. 063-25437) is the well closest to these seismic lines with the requisite density and sonic logs needed to create a synthetic seismic trace (Figure 4). The Ormsby wavelet used for the synthetic seismic trace calculation was extracted from the processed reflection seismic sections and is shown for reference in the central vertical column labeled “Wavelet Ormsby_2(0)” (Figure 4). This zero phase wavelet was consistent with respect to the different seismic sections and time intervals of interest. The reflection coefficients were calculated from the sonic slowness (DT) and density (RHOB), which were then used to estimate acoustic impedance. From the acoustic impedance, reflection coefficients (RC) were calculated and convolved with the Ormsby wavelet to produce the synthetic seismic result. These data are shown on the left portion of Figure 4. Vertical columns show the synthetic seismic traces and were replicated to give a better sense of the character of the synthetic reflections. The traces in the vertical column labeled “Synthetic (+)” were calculated with normal phase and the traces shown in the vertical column labeled “Synthetic (-)” are calculated with inverse phase. These columns can be directly compared with the reflection seismic data to estimate horizon location and estimate the predicted seismic response from these units encountered in this well.

MAPPING THE ONONDAGA LIMESTONE In order to illustrate how remote sensing data may be manipulated to resolve subsurface geologic structure, BTGS used ARM’s seismic survey data set to map the top of the Middle Devonian Onondaga Limestone, a prominent limestone formation that is immediately overlain by the Marcellus shale (see Figure 3). We used PETRASeis® V2 and PETRA® V3.8 software to interpret fault locations and map geologic structure, respectively. We created a PETRASeis® project by importing both the seismic line location data and processed 2D seismic survey data set. As part of this process, location data for Line 102 was shifted -179 milliseconds in order to tie it to Line 103. Unfortunately, Line 101 could not be tied to Line 103 because of the complexity of faulting observed in these two 2D lines where they intersect. Fault and formation top interpretations from the ARM seismic survey report (Vogel et al., 2010) were imported into the PETRASeis® project to facilitate our interpretive work. We reviewed the ARM data, and then interpreted additional faults and Devonian-age formation tops throughout the study area. The Onondaga Limestone top was chosen as the next continuous reflector beneath the Tully Limestone. Using these data, we created

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Figure 4. Berringer well synthetic seismic trace.

To map the location of faults interpreted from seismic lines, we loaded the well, seismic line, and fault data into a PETRA® project created for this purpose. Faults were connected between the seismic lines if their offset directions and magnitudes were comparable and did not conflict with available well data. Because the orientation of a fault cannot be determined from 2D seismic data alone, we also took into consideration the locations of regional folds as published by Faill (2011). In addition, faults in the Oriskany Sandstone, as mapped by Cate (1962), were digitized and incorporated into our analysis. Because the Onondaga–Salina interval is faulted extensively in the area of surface anticlines (Beardsley et al., 1999), faults were extended from the seismic lines roughly parallel to these regional folds where well or other data supported the existence of a fault.

In the final interpretation, most of the faults follow the trend of the Jacksonville anticline. Two faults correlated well with those mapped by Cate (1962), and these faults were extended to match previously mapped faults. The southernmost fault on Line 101 was interpreted as roughly parallel to the Greensburg syncline (Figure 2). After mapping the faults, we created a geologic structure map for the top of the Onondaga Limestone in the PETRA® project. The PETRASeis® depth map was not used to construct this map due to the significant amount of noise encountered during data acquisition. Instead, structure contours were drawn manually in PETRA® using Onondaga top depths from wells and depths calculated along the seismic lines. The trends of the contours away from the seismic lines were developed using data from deep wells beyond the extent of this 7

map and trends from a shallower structure map created on the Upper Devonian Bradford sand. This particular horizon was used because it is the deepest sand with significant well control in the study area. The final Onondaga Limestone geologic structure contour map reveals complicated structure along the Jacksonville anticline, consisting of a series of en-echelon lowangle normal faults (Plate 1). These faults extend up into Middle or Upper Devonian shales. The deepest faults do not penetrate the décollement near the top of the Lockport Dolomite.

ACKNOWLEDGMENTS The authors wish to acknowledge John Quigley, former DCNR Secretary, for his leadership, focus, and support of BTGS’ research during his tenure with the Commonwealth. In addition, we extend thanks to John A. Harper (BTGS, retired) for his decades of service to the Commonwealth, breadth of knowledge, and technical support on matters of regional geologic structure, stratigraphy, and oil and gas activity in Pennsylvania. Finally, our thanks also go to Gale Blackmer, Michael Moore, and Thomas Whitfield of BTGS for providing thoughtful reviews and helpful GIS expertise.

REFERENCES CITED Beardsley, R. W., Campbell, R. C., and Shaw, M. A., 1999, Appalachian plateaus, Chapter 20 of Shultz, C. H., ed., The geology of Pennsylvania: Pennsylvania Geological Survey, 4th ser., Special Publication 1, p. 287-289. Cate, A. S., 1962, Subsurface structure of the Plateau region of north-central and western Pennsylvania on top of the Oriskany Formation: Pennsylvania Geological Survey, 4th ser., Map 9, scale 1:250,000. Department of Conservation and Natural Resources (DCNR), 2009, Geologic sequestration opportunities in Pennsylvania, Pennsylvania Department of Conservation and Natural Resources: 150 p. (report on file at BTGS). Faill, R. T., compiler, 2011, Folds of Pennsylvania—GIS data and map: Pennsylvania Geological Survey, 4th ser., Open-File Report OFGG 11–01.0, scale 1:500,000. Vogel, P. N., King, S. M., and Seaton, W. J., 2010, Seismic survey report, carbon sequestration storage investigatory activity: Project No. DGS A 171-4 Indiana County, Pennsylvania: Hershey PA, ARM Geophysics, 25 p. (unpublished report on file at BTGS).

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