Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities

The Shahejie Formation (Fm) in the Bohai Bay Basin is well-known for its substantial conventional resource potential and long-term history of exploration. Shale oil has been confirmed as a sustainable resource following breakthroughs in shale exploration in the first and third members of the Paleoge...

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Main Authors: Zhuoya Wu, Xianzheng Zhao
Format: Article
Language:English
Published: MDPI AG 2022-09-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/15/19/7078
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author Zhuoya Wu
Xianzheng Zhao
author_facet Zhuoya Wu
Xianzheng Zhao
author_sort Zhuoya Wu
collection DOAJ
description The Shahejie Formation (Fm) in the Bohai Bay Basin is well-known for its substantial conventional resource potential and long-term history of exploration. Shale oil has been confirmed as a sustainable resource following breakthroughs in shale exploration in the first and third members of the Paleogene Shahejie Fm (Mbr1 and Mbr3) in Qikou Sag, particularly Mbr3, which has a more desirable output. However, the limited distribution of exploration wells for shale oil around the southwest of Qikou Sag calls for a comprehensive evaluation of shale oil (or gas) potential in all of Qikou Sag. Here, we clarify the shale oil (or gas) resource potential and areas favorable for exploration in Mbr<sub>3</sub> by using a hydrocarbon generation potential model (HGPM) based on the material balance method and the principle of hydrocarbon (HC) generation dynamics. Apart from the quantified characteristics of the oil generation process of Mbr<sub>3</sub> source rocks, the source rocks of both Mbr<sub>1</sub> and Mbr<sub>3</sub> were compared to interpret the discrepancies in HC generation. The results show that Mbr3 source rocks have high-quality geological and geochemical features, a thickness of 1200 m, and adequate organic matter (1.66% TOC on average, dominated by kerogen II&III, and in the mature stage). The threshold of expulsion is R<sub>o</sub> = 0.78%; correspondingly, HC generation potential (Q<sub>g</sub>), HC expulsion potential (Q<sub>e</sub>), and retention potential (Q<sub>r</sub>) are, at maximum, 605.89, 169.65, and 436.24 mg HC/g TOC. The intensity of HC generation (I<sub>g</sub>), expulsion (I<sub>e</sub>), retention (I<sub>r</sub>), and effective retention (I<sub>re</sub>) is focused on the main depression and the Qibei Sub-sag and can reach as high as 250 × 10<sup>4</sup>, 65 × 10<sup>4</sup>, 170 × 10<sup>4</sup>, and 110 × 10<sup>4</sup> t/km<sup>2</sup>, respectively. The resource potential for the retention of shale was calculated to be 13.3 × 10<sup>8</sup> t (movable shale oil and gas 8.0 × 10<sup>8</sup> t), and conventional and tight oil or gas resources were calculated to be 4.7 × 10<sup>8</sup> t (equivalent oil resources). Favorable exploration targets are spread around the main depression and the Qibei Sub-sag. There are disparities in the thermal process and thermal generation, and expulsion features between Mbr<sub>1</sub> and Mbr<sub>3</sub> source rocks are derived from kerogen-type and non-isolated deposit environments. Thus, a quantitative, advanced evaluation and a comparison offer more precise exploration predictions of shale in this Fm and further boost the low-risk exploration process.
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spelling doaj.art-1b7bbe3f9bab4059ae36aad45a64d29d2023-11-23T20:12:47ZengMDPI AGEnergies1996-10732022-09-011519707810.3390/en15197078Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion CapabilitiesZhuoya Wu0Xianzheng Zhao1Research Institute of Petroleum Exploration & Development, China National Petroleum Corporation, Beijing 100083, ChinaPetroChina Dagang Oilfield Company, Tianjin 300280, ChinaThe Shahejie Formation (Fm) in the Bohai Bay Basin is well-known for its substantial conventional resource potential and long-term history of exploration. Shale oil has been confirmed as a sustainable resource following breakthroughs in shale exploration in the first and third members of the Paleogene Shahejie Fm (Mbr1 and Mbr3) in Qikou Sag, particularly Mbr3, which has a more desirable output. However, the limited distribution of exploration wells for shale oil around the southwest of Qikou Sag calls for a comprehensive evaluation of shale oil (or gas) potential in all of Qikou Sag. Here, we clarify the shale oil (or gas) resource potential and areas favorable for exploration in Mbr<sub>3</sub> by using a hydrocarbon generation potential model (HGPM) based on the material balance method and the principle of hydrocarbon (HC) generation dynamics. Apart from the quantified characteristics of the oil generation process of Mbr<sub>3</sub> source rocks, the source rocks of both Mbr<sub>1</sub> and Mbr<sub>3</sub> were compared to interpret the discrepancies in HC generation. The results show that Mbr3 source rocks have high-quality geological and geochemical features, a thickness of 1200 m, and adequate organic matter (1.66% TOC on average, dominated by kerogen II&III, and in the mature stage). The threshold of expulsion is R<sub>o</sub> = 0.78%; correspondingly, HC generation potential (Q<sub>g</sub>), HC expulsion potential (Q<sub>e</sub>), and retention potential (Q<sub>r</sub>) are, at maximum, 605.89, 169.65, and 436.24 mg HC/g TOC. The intensity of HC generation (I<sub>g</sub>), expulsion (I<sub>e</sub>), retention (I<sub>r</sub>), and effective retention (I<sub>re</sub>) is focused on the main depression and the Qibei Sub-sag and can reach as high as 250 × 10<sup>4</sup>, 65 × 10<sup>4</sup>, 170 × 10<sup>4</sup>, and 110 × 10<sup>4</sup> t/km<sup>2</sup>, respectively. The resource potential for the retention of shale was calculated to be 13.3 × 10<sup>8</sup> t (movable shale oil and gas 8.0 × 10<sup>8</sup> t), and conventional and tight oil or gas resources were calculated to be 4.7 × 10<sup>8</sup> t (equivalent oil resources). Favorable exploration targets are spread around the main depression and the Qibei Sub-sag. There are disparities in the thermal process and thermal generation, and expulsion features between Mbr<sub>1</sub> and Mbr<sub>3</sub> source rocks are derived from kerogen-type and non-isolated deposit environments. Thus, a quantitative, advanced evaluation and a comparison offer more precise exploration predictions of shale in this Fm and further boost the low-risk exploration process.https://www.mdpi.com/1996-1073/15/19/7078source rockShahejie formationhydrocarbon generationexpulsion capabilitiesQikou Sag
spellingShingle Zhuoya Wu
Xianzheng Zhao
Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities
Energies
source rock
Shahejie formation
hydrocarbon generation
expulsion capabilities
Qikou Sag
title Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities
title_full Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities
title_fullStr Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities
title_full_unstemmed Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities
title_short Petroleum Resource Potential Assessment of Members 1 and 3 of the Paleogene Shahejie Formation, Qikou Sag: Insights from Hydrocarbon Generation and Expulsion Capabilities
title_sort petroleum resource potential assessment of members 1 and 3 of the paleogene shahejie formation qikou sag insights from hydrocarbon generation and expulsion capabilities
topic source rock
Shahejie formation
hydrocarbon generation
expulsion capabilities
Qikou Sag
url https://www.mdpi.com/1996-1073/15/19/7078
work_keys_str_mv AT zhuoyawu petroleumresourcepotentialassessmentofmembers1and3ofthepaleogeneshahejieformationqikousaginsightsfromhydrocarbongenerationandexpulsioncapabilities
AT xianzhengzhao petroleumresourcepotentialassessmentofmembers1and3ofthepaleogeneshahejieformationqikousaginsightsfromhydrocarbongenerationandexpulsioncapabilities