Recent Vaca Muerta (VM) and China hypersaline shale oil results, however, demonstrate that low GOR heavier Black shale oil (LGBSO) with higher viscosity could overperform HG-LTO. In another paper in this conference, we discuss the drivers for LGBSO prolific production, oil and gas expansion, PVT phase change; and this paper will present the maturity as the driver for LGBSO which provides the nano-porosity and pressure for LGBSO production. We use isotope-maturity as a powerful method to correctly delineate the maturity of VM alike shale fields. The maturity and production data are combined to access the latest Technically Recoverable Resources of oil in VM.
Light Tight Oil with high Gas to Oil Ratio (GOR, i.e., HGLTO) and low viscosity has been long considered as the unique requirement for shale tight oil. The established belief is corroborated by the abundant shale oil yields in prominent North American shale regions like Bakken, Eagle Ford, and Permian, where HGLTO predominates. However, this notion has prompted critics of shale oil, such as Art Berman and many others, to use the "HGLTO = Shale Oil" equation and argue that shale oil is unable to replicate the properties of conventional black oil, and the inundation of HGLTO has only led to a scarcity of mid-distillates, notably diesel, which forms the backbone of logistical operations in modern society. With electric vehicles becoming increasingly accessible for smaller passenger cars, black oil and its principal refinery mid-distillates are now viewed as crucial transitional fuels towards a renewable energy future. The ongoing Russia-Ukraine conflict has further exacerbated the shortage of mid-distillates and black oil, intensifying the urgency to explore new sources of unconventional black oil.
In the past 3 years, shale oil from VM continue to surprise us, i.e. now with EUR at least twice the best shale patch in the US.
The surprise is that the new strong driving forces are from "less mature" blocks producing new breed of high prolific Black Shale Oil, i.e., with API < 35°, and Low GOR ranging 50∼550scf/bbl, i.e., LGBSO. In a separate paper submitted in this conference, we analyze the reasons behind the productivity of LGBSO versus HGLTO in terms of viscosity and PVT phase diagram. Here in this paper, we answer the questions left from the previous paper, i.e., why LGBSO is prolific in terms of maturity and over pressure generation? and why US does not have much LGBSO in the shale oil fields? and how to identify the LGBSO with the proper maturity and nano porosity and overpressure?
