Identifying the Point Pleasant formation's condensed intervals with XRF chemostratigraphy

The Point Pleasant Formation is a major unconventional drilling target in eastern Ohio; however, obstacles arise from its highly variable total organic carbon (TOC). This research has mapped the organic-rich condensed intervals (CI) of the study area, based on 31 wells in eastern Ohio, using a sequence stratigraphic framework. The Point Pleasant Formation is problematic for traditional methods of sequence stratigraphy, due to the complex nature of mixed carbonate-siliciclastic systems and a lack of distinct facies changes within the relatively monotonous section. These issues have been circumvented with the use of geochemical proxies. Relative elemental abundances, for two wells with associated core, have been measured with a handheld X-ray fluorescence spectrometer (pXRF). Strata display unique geochemical trends. The trends observed from proxies for terrigenous sedimentation (Ti, Zr and Rb), marine sedimentation (Ca and Sr), clay sedimentation (Al and K), upwelling (P), pyrite minerals (Fe and S) and biogenic quartz (Si/Al). The chemofacies present in the core suggest the presence of Lowstand Systems Tract (LST), Transgressive Systems Tract (TST) and the Highstand Systems Tract (HST). Condensed intervals are associated with the end of the Transgressive Systems Tract (TST) and capped by the Maximum Flooding Surface (MFS). The CI of the remaining wells without core are predicted based on shared wireline log responses, primarily gamma, resistivity, and density motifs. The most significant signatures used in identifying the CI come from gamma and resistivity. The identified and predicted CI have been mapped with Petrel. Two cores and wireline logs from eastern Ohio, donated by EMF Geoscience Inc. and Artex Energy Group LLC, have demonstrated that this pattern is mappable and laterally reproducible.