Analysis of Geologic CO2 Migration Pathways in Farnsworth Field, NW Anadarko Basin

Abstract

This study reports on analyses of natural, geologic CO2 migration paths in Farnsworth Oil Field, northern Texas, where CO2 was injected into the Pennsylvanian Morrow B reservoir as part of enhanced oil recovery and carbon sequestration efforts. We interpret 2D and 3D seismic reflection datasets of the study site, which is located on the western flank of the Anadarko basin, and compare our seismic interpretations with results from a tracer study. Petroleum system models are developed to understand the petroleum system and petroleum- and CO2-migration pathways. We find no evidence of seismically resolvable faults in Farnsworth Field, but interpret a karst structure, erosional structures, and incised valleys. These interpretations are compared with results of a Morrow B well-to-well tracer study that suggests that inter-well flow is up-dip or lateral. Southeastward fluid flow is inhibited by dip direction, thinning, and draping of the Morrow B reservoir over a deeper, eroded formation. Petroleum system models predict a deep basin-ward increase in temperature and maturation of the source rocks. In the northwestern Anadarko Basin, petroleum migration was generally up-dip with local exceptions; the Morrow B sandstone was likely charged by formations both below and overlying the reservoir rock. Based on this analysis, we conclude that CO2 escape in Farnsworth Field via geologic pathways such as tectonic faults is unlikely. Abandoned or aged wellbores remain a risk for CO2 escape from the reservoir formation and deserve further monitoring and research.

Coupled Hydromechanical Modeling and Assessment of Induced Seismicity at FWU: Utilizing Time-Lapse VSP and Microseismic Data

“…Additionally, faults within sedimentary strata-intersecting basement rocks can lead to the occurrence of high-magnitude seismic events when induced to slip. A study conducted by van Wijk et al [26] found no direct evidence of faults in the reservoir or caprocks in the FWU.…”

“…Further work performed by Ross-Coss [23] characterized the formation heterogeneity by defining eight hydrologic flow units based on the porosity-permeability relationships interpolated from core flooding experiments and petrographic studies. study performed by van Wijk et al [26], using 3D seismic data and tracer experiments to understand the flow directions of the injected CO 2 , indicated that the impermeable caprock makes it less likely for injected CO 2 to migrate vertically or flow southward. A defining characteristic of the FWU geology is that the injection zone (Morrow B) is not in direct contact with the Precambrian basement.…”

“…Figure 3 presents the stratigraphic column of the FWU, highlighting the main production interval and different rock sections lying above and beneath the reservoir. A study performed by van Wijk et al, [26], using 3D seismic data and tracer experiments to understand the flow directions of the injected CO2, indicated that the impermeable caprock makes it less likely for injected CO2 to migrate vertically or flow southward. A defining characteristic of the FWU geology is that the injection zone (Morrow B) is not in direct contact with the Precambrian basement.…”

“…The different colors denote the different rock formations in FWU. (Figure modified from van Wijk et al,[26]).…”

Forecasting CO2 Sequestration with Enhanced Oil Recovery

“…Van Wijk et al [8] report on the analyses of natural, geologic CO 2 migration paths in and near the FWU on the western flank of the Anadarko Basin. The paper interprets 2D and 3D seismic reflection datasets from the study site and compares seismic interpretations with results from a tracer study.…”