Citation: Woo, J.; Choi, J.; Yoon, S.H.; Rhee, C.W. Verification and Application of Sequence Stratigraphy to Reservoir Characterization of Horn River Basin, Canada. Minerals 2022, 12, 776. https://doi.org/10.3390/ min12060776 Academic Editors: Yi Fang, Yong Li, Brandon Schwartz, Zhuang Sun and Stanislaw Mazur Received: 4 April 2022 Accepted: 15 June 2022 Published: 18 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). minerals Article Verification and Application of Sequence Stratigraphy to Reservoir Characterization of Horn River Basin, Canada Juhwan Woo 1, * , Jiyoung Choi 2 , Seok Hoon Yoon 3 and Chul Woo Rhee 1, * 1 Department of Earth and Environmental Sciences, Chungbuk National University, Cheongju 28644, Korea 2 Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, Korea; jychoi@kigam.re.kr 3 Department of Earth and Marine Sciences, Jeju National University, Jeju 63243, Korea; shyoon@jejunu.ac.kr * Correspondence: jhonta@chungbuk.ac.kr (J.W.); gloryees@chungbuk.ac.kr (C.W.R.); Tel.: +82-43-261-3136 (J.W.) Abstract: Shale reservoirs, the most important unconventional resource, are difficult to character- ize. Shale formations require detailed interpretation of geological, petrophysical, and geochemical analyses, and an integration of these disciplines. In terms of geological interpretation, the commonly used sequence stratigraphy analysis includes a lithofacies analysis. The application of sequence stratigraphy to shales facilitates the ability to relate between lithofacies and mineral composition, petrophysical parameters, and kerogen contents, which are affected by depositional setting. The classification of lithofacies is indispensable for reservoir quality prediction. In this study, porosity, permeability, and TOC content largely depend on lithofacies, and their correlation coefficient is relatively high. The sequence stratigraphic interpretation shows that organic carbon content usually increases within the maximum flooding surfaces and decreases stepwise. However, the relationship between total organic carbon contents and systems tract is less direct and redox dependent. Keywords: shale sequence stratigraphy; marine shale; Horn River Formation; Horn River Basin 1. Introduction Shales are a common source of hydrocarbons and can act as reservoirs of oil and gas deposits. The reservoir quality of the shales is complex due to their heterogeneity, which is related to the lithofacies and depositional environments [1,2]. Understanding shale reservoirs can be assessed in the framework of sequence stratigraphy, through integrating diverse data of geological, geophysical, and geochemical features. It helps to correlate and explain the relationship between lithofacies and their geological character, because porosity, permeability, total organic carbon (TOC) content, and mineral composition of shale reflect spatiotemporal variation of fine-grained deposits. Most studies have recognized reservoir quality in relation to relative sea-level fluctuation within a sequence stratigraphic analysis [3–6]. Despite their overall importance, the relationship between reservoir quality and lithology is poorly studied. The Horn River Formation, deposited in the Western Canada Sedimentary Basin, is one of the well-studied mudstone deposits in Canada. It is composed of an alternating sequence of siliceous mudstone, argillaceous mudstone, and calcareous mudstone [7–10]. Those are divided into the Evie Member, the Otter Park Member and the Muskwa Formation, in ascending order. The geological characteristics of the Horn River Formation have been studied based on sedimentological descriptions, geochemical analysis, wireline log analysis, and sequence stratigraphic analysis [8,10–12]. There have been several sequence stratigraphic interpretations of the Horn River Formation [8,10–12]. The Evie Member was interpreted as deposited during a second-order highstand stage [8,10], and consists of a third-order transgressive systems tract (TST) and an overlying regressive systems tract (RST) [11]. The Otter Park Member is interpreted as a second-order lowstand stage in the middle Devonian carbonate, and a transgressive stage in its upper part [8,10], consisting Minerals 2022, 12, 776. https://doi.org/10.3390/min12060776 https://www.mdpi.com/journal/minerals