Seismic Evaluation of the Fruitland Formation with Implications on

Leakage Potential of Injected CO2 Thomas H. Wilson1,2 e-mail: [email protected]; Art Wells1, George Koperna3: 1) National Energy Technology Center; 2) West Virginia University; 3) Advanced Resources International, Inc.

1) Abstract (see proceedings for full text) 2) Introduction Subsurface characterization activities undertaken in collaboration Seismic analysis undertaken in this study consists primarily of post stack attribute with the Southwest Regional Carbon Sequestration Partnership on analysis. Attribute analysis refers to an extensive collection of processes designed to their San Juan Basin pilot test include acquisition of geophysical enhance features of interest in subsurface interpretation. Attributes calculated and logs, time lapse VSP and analysis of 3D seismic data from the site. evaluated in this study included a variety of edge and discontinuity enhancement The project is funded by the U.S. Department of Energy and is algorithms. The motivation for this analysis is to identify potential fracture zones and managed by the National Energy Technology Laboratory. CO2 faults that may breach the injection zone and lead to migration of injected CO2 into injection began in late July of 2008 and continued through July of overlying strata. The project is funded by the U.S. Department of Energy and is

2009. Total CO2 injection volume was approximately 300MMcf. managed by the National Energy Technology Laboratory. Subsurface characterization activities are critical to the evaluation In the following discussion, an example of the 3D post-stack seismic processing of reservoir integrity and the potential that leakage of injected CO efforts is illustrated. The analysis suggests the possibility for internal 2 The NW-SE line (above) might occur. In the 2D seismic display compartmentalization of the Fruitland coals through this area accompanied by fairly illustrates a similar level Work discussed in this presentation focuses primarily on the above, locally steepened extensive system of fracture networks. Seismic analysis presented here suggests that of reflection analysis of 3D seismic data from the area. The 3D seismic view of dips are evident across the subsurface geology is quite complex at the scale of the pilot site. Amplitude discontinuity along the the Fruitland Formation shows considerable detail not inferred from the area. This line trends anomalies are numerous in the vicinity of the injection well in addition to kilometer axis of the basin. Local well log correlations in the area. The pattern of internal reflection northeast-southwest wavelength structures (see figures at left). Regional studies by Fassett (1997), Wray structural features are events is marked by significant internal discontinuity. Fruitland Considerable internal (2000), reveal the presence of considerable heterogeneity within the Fruitland also evident in the coal reflection events reveal the presence of local fold-like discontinuity of reflection Formation and individual seams. The detailed study of Ayers and Zellers (1994) display. structures with wavelengths of 1 km to 3.5km accompanied by relief events is evident conducted near the pilot site reveals considerable complexity in the Fruitland Fm of 6 feet to 60 feet. Some of the structures observed in the Fruitland throughout. depositional systems. Fassett (1997) indicates that continuity of subsurface coals are present in overlying Paleocene and Late Cretaceous intervals. Shallower reflection events associated with the upper Kirtland over distances of a mile is speculative, at best. Pinchouts, local fault truncations, Post-stack processing and interpretation suggests that the Fruitland Shale, the Ojo Alamo Sandstone and Nacimiento Fm. channel scour and facies changes are all encountered in the Fruitland coals. Seismic and primary seal are deformed by small faults and fracture zones. analysis provides a glimpse of some of this heterogeneity.

Conclusions Fruitland Formation Isochore Fruitland Base Time Structure The Southwest Regional Partnership’s San Juan Basin carbon sequestration pilot

site lies about 10 miles southwest of the axis of the San Juan Basin. CO2 was injected into the Fruitland Formation over depths ranging from 2,940 to 3,150 feet subsurface.

During the course of a year, nearly 18,000 tons of CO2 were injected into the Fruitland Formation. Subsurface characterization activities were undertaken in this study to help assess site integrity and provide a framework for interpretation of NETL’s perfluorocarbon tracer and soil gas observations at the site. Post-stack processing of the 3D seismic was undertaken to help enhance seismic indicators of fracturing and faulting. In this study we incorporated a post-stack process consisting of the absolute value of the derivative of the seismic amplitudes. 3) An automatic gain control (AGC) was applied to the output to help equalize attribute amplitude over short time windows. The result of this simple process suggests the Travel time through the Fruitland sequence (map view, above left) drops by approximately ? Pinchout in the 8 milliseconds to the southwest from the injection well to the COM A 300 production well. Pictured Cliffs Ss. presence of considerable fracturing and minor faulting within the Kirtland Shale Using an average log-derived velocity of 10,600 fps, this 8 ms corresponds to about 40 4) caprock (e.g. figures lower left). Indicators for extensive fracturing and faulting within feet of thinning. In some areas, thinning of the Fruitland sequence coincides with a time the Fruitland sequence are much less apparent. The Schlumberger Ant Tracking structural high at the base of the sequence (map view, above right). Reflection patterns in Post stack processing (right) enhances stratigraphic features in the underlying Pictured process was also used, and it delineates subtle zones of reflection discontinuity that Cliffs Sandstone along with events in the Fruitland sequence. Fruitland reflection events the Pictured Cliffs Sandstone are interpreted as northwest trending shoreline sands. form clusters with approximate N50E to N55E trend. Similar patterns of discontinuity Thinning could in part be related to differential compaction over these sand bodies. appear to thin and pinch out in places over the high in the underlying Pictured Cliffs Ss. are observed in the Kirtland and overlying Tertiary intervals (interpreted Ojo Alamo and Nacimiento seismic sequences). The results of the analysis suggest that several small faults and fracture zones 5) EPNG COMEPNGSP-B A SPBCOM ECSP-A A A 300SP INGSP-C A COM 1 COM SPC A 300 A ING1 Post stack processing (at right ) enhances

Line: 925.0 925.0 925.0 925.0 925.0 925.0 925.0 925.0 925.0 925.0 disrupt overlying intervals and to less extent, the reservoir interval. However, Trace: 580.0 600.0 620.0 640.0 660.0 680.0 700.0 720.0 740.0 760.0 subtle seismic features that may be associated with fracture zones and fault interpreted faults and fracture zones have limited vertical extent and major systems. Between the Fruitland top and penetrative faults have not been observed at the site. 0.350 0.350 1626:Naci base subtle features are also enhanced Acknowledgements that may be associated with vertically 0.400 0.400 This technical effort was performed in support of the National Energy Technology Laboratory’s on-going research

1989:Ojo juxtaposed stratigraphic pinchouts or in carbon sequestration under RDS contract DE-AC26-04NT41817-6060404000. We’d like to thank Dave 2018:C1 2056:Kirt internal faults. Some of these occur near Wildman and Donald Martello, our DOE-NETL project managers and Scott Reeves (BG Group) for their support 0.450 0.450 the periphery of the pilot area as defined by and advice; Brian McPherson and Reid Grigg of the Southwest Regional Partnership for their help in facilitating The Kirtland Shale The primary seal our involvement in their San Juan Basin pilot test; and Ryan Frost, Tom Cochrane and Bill Akwari of Conoco 0.500 0.500 the production wells. Considerable Phillips for their help to facilitate many of the activities on the site. BP’s participation in the project is greatly The Kirtland Shale 2690:C2 evidence of fracturing and minor faulting is appreciated. We’d also like to thank Bill O’Dowd, the DOE-NETL project manager for the Southwest Regional primary seal (caprock) 2826:Fr 0.550 0.550 also observed in the overlying Kirtland Partnership, for his support and advice on these efforts and for his review comments. The seismic data used in 2950:UFZ-T this evaluation are proprietary and provided through the Southwest Regional Partnership. Tom Wilson is an Fruitland Formation 2987:UFC-B Shale – the primary seal. While large 3072:MFC-B3056:MFC-T reservoir zone 3111:LFC-T Institute Fellows working with NETL under the Institute for Advanced Energy Solutions (IAES) and appreciates 0.600 0.600 continuous faults extending through the Fruitland Formation the opportunity to work jointly with research staff in the Office of Research and Development at NETL. seal to the surface are not observed, reservoir zone 0.650 0.650 considerable fracturing of overlying References •Ayers, W. B., Jr., and Zellers, S. D., 1994, Coalbed methane in the Fruitland Formation, Navajo Lake area: geologic controls on intervals is interpreted. If the integrity of occurrence and producibility; in Coalbed methane in the Upper Cretaceous Fruitland Formation, San Juan Basin, New Mexico and 0.700 0.700 the reservoir and primary seal are Colorado, New Mexico Bureau of Mines and Mineral Resources, Bulletin, 146, pp. 63- 85. compromised, long-term escape to the •Donaldson, A. C., 1979, Origin of coal seam discontinuities; in Donaldson, A. C., Presley, M. W., and Renton, J. J. (eds.), Carboniferous Conventional seismic display does not reveal features that Coal Guidebook: West Virginia Geological and Economic Survey, Bulletin B-37-1, pp 102-132. surface might be facilitated. Site •Fassett, J., 1997, Subsurface correlation of Late Cretaceous Fruitland Formation coal beds in the Pine River, Florida River, Carbon could be interpreted as faults or fracture zones. Based on the Junction, and Basin Creek gas-seep areas, La Plata County, Colorado: U. S. Geological Survey Open File Report 97-59, 22p. above seismic view we are likely to conclude the primary monitoring will ensure detection of any CO2 •Tyler, R., Laubach, S. E., and Ambrose, W. A., 1991, Effects of compaction on cleat characteristics: preliminary observations; in Ayers, Absolute value of trace derivative with 75ms AGC. W. B., Jr., and others, 1991, Geologic and hydrologic controls on the occurrence and producibility of coalbed methane, Fruitland seal offers a secure, long term barrier to CO2 migration. escape should it occur. Formation, San Juan Basin: The University of Texas at Austin, Bureau of Economic Geology, report prepared for the Gas Research Institute, GRI-91/0072, pp. 141-151.