ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Economic Geology
This article is part of the Research TopicShale Oil Micro-Migration and Its Effect on Shale Oil Differential EnrichmentView all 12 articles
Structural configuration and its controls on shale oil accumulation of the Wulalike Formation at southern section of western margin, Ordos Basin
Provisionally accepted
- 1PetroChina Exploration Development Institute of Changqing Oilfield Co, Xi'an, China
- 2Chengdu University of Technology, Chengdu, China
- 3Xi'an Shiyou University, Xi'an, China
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The Wulalike Formation in the southern Ordos Basin represents an emerging marine shale oil play, with recent discoveries challenging traditional views of its low-TOC and low-porosity potential. The current study integrates 3D seismic data, geochemistry (TOC, Rₒ), and structural analysis to unravel tectonic controls on shale oil accumulation. The western margin features three structural zones: (1) a reverse-thrust belt (Huianbu-Shajingzi fault), (2) a thrust-extension zone (Yandunshan-Majiatan blocks), and (3) a stable eastern zone. Unlike the northern detachment systems, the southern section exhibits monoclinal thrusts, evidenced by near-vertical Ordovician strata (Qiujianjia section) and high-angle thrusts. Fault analysis highlights that fault activity reached its peak during the Permian-Triassic transition (252 - 201 Ma), with faults inheriting structural characteristics from Caledonian and Yanshanian-Indosinian orogenies. Early uplift in the south led to lower thermal maturity (Rₒ = 0.83%, TOC = 0.82%) and preserved oil, while the central-north reached gas-window maturity (Rₒ = 1.6%, TOC = 1.13%). Meanwhile, different unconformities in southern versus northern sections reflect differential tectonic evolution. Structurally stable inner thrust-sheet zones (e.g., Shajingzi) retained intact strata and deeper burial, whereas sheet-edge zones underwent erosion and leakage. The Wulalike shale oil model emphasizes tectonic control on preservation, prioritizing inner-sheet zones for exploration in the western margin of the Ordos Basin. These insights redefine prospects for low-TOC shale oil in thrust belts.
Keywords: Ordos Basin, Shale oil, thermal maturity, Thrust tectonics, Wulalike formation
Received: 24 Dec 2025; Accepted: 03 Feb 2026.
Copyright: © 2026 Wei, Su, Ren, Yang, Jing, Liu and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Zhongtang Su
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