--> Utica-Pt. Pleasant Condensate Yield Prediction Using 3-D Maturity Modeling

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Utica-Pt. Pleasant Condensate Yield Prediction Using 3-D Maturity Modeling

Abstract

The Utica-Pt. Pleasant unconventional play produces gas and condensate in eastern Ohio and western Pennsylvania. Condensate yield is important to the commercial success of the play, so there is in interest in improving the pre-drill prediction of this parameter. In general, measured and modeled maturity can be used as a predictive tool to distinguish areas prospective for oil, wet gas and dry gas for unconventional plays. Usually oil is found in the 0.6–1.1 Ro range, wet gas from 1.1–1.7 and dry gas over 1.7. In this case we attempt to predict condensate yield rather than just wet gas based on a range of modeled maturity. A 3D maturity model of the Utica-Point Pleasant Basin was constructed in order to predict maturity (vitrinite reflectance equivalence or VRE) for multiple stratigraphic horizons. The horizons modeled were the Berea, Marcellus, Top Ordovician, Utica, Top Knox, Base Knox and Basement. In addition to structural horizons a map estimating late Paleozoic erosion was constructed. An uncorrected temperature gradient map from bottom hole temperatures from nearly 1500 wells was also made. This map was adjusted to correlate the Utica-Point Pleasant modeled maturity to the rock maturity for this interval. Utica-Point Pleasant model maturity to rock maturity correlation coefficient was about .50. This calibrated temperature gradient map was then used to model the other six horizons. Condensate yield was calculated from Utica-Point Pleasant production data for 256 wells provided by the Ohio Department of Natural Resources. These condensate yields were correlated to Utica-Pt. Pleasant modeled maturity and a good correlation (R2 = .76) was found between these data sets. The Utica-Point Pleasant modeled maturity map was then transformed to a condensate yield map by means of the equation. It was observed that there was a geographic difference between the relative condensate yield at a given maturity. Wells in Guernsey, Noble and Washington Counties have a higher condensate yield than wells to the north of this area in Harrison, Carroll and Columbiana Counties. Therefore, one function from maturity to condensate yield for the entire eastern Ohio area was not sufficient. One function with relatively lower condensate yield was used for the northern area and another was used for the southern area. This technique has proven successful in other North American unconventional plays.