Analysis of oil and gas distribution and exploration potential in oil-rich depression: Taking Dongpu Depression as an example

doi:10.13745/j.esf.sf.2024.2.26

Abstract

Abstract:

The major oil fields in the Bohai Bay Basin have undergone long-term detailed exploration, yet the latest resource assessments still indicate a large potential for remaining resources in oil-rich depressions with high resource abundance. These areas will continue to be a long-term focus for exploration and development. Deepening the understanding of hydrocarbon accumulation patterns in oil-rich depressions is crucial for guiding future oil and gas exploration. This paper begins from the perspective of source rocks, clarifying the hydrocarbon generation characteristics of the Paleogene lacustrine shales in the Dongpu Depression and the coal-bearing source rocks of the Upper Paleozoic. It then integrates typical oil and gas reservoir analyses and reservoir evaluation units to establish a correspondence between source and reservoir. By combining this with other accumulation factors, it aims to develop hydrocarbon accumulation models and clarify the patterns of remaining oil and gas enrichment. The research indicates that the oil-rich depression in the Dongpu Depression is characterized by “proximity to source aggregation, continuous accumulation, and fault-controlled richness”. The hydrocarbons primarily originate from high-quality source rocks with TOC greater than 1.0%. The richness of oil and gas in the oil-rich zones is mainly due to the presence of multiple sets of high-quality source rocks, multiple oil and gas systems, and multiple stages of hydrocarbon accumulation, referred to as the “three multiplicities”. In the Dongpu Depression, coalbed methane is primarily distributed in areas where the thermal maturity level of coal-bearing source rocks (Ro) exceeds 1.3%, exhibiting both in-source and out-of-source accumulation modes. The findings of this study not only provide technical support for the exploration of conventional oil and gas reservoirs but also for the exploration of thin-layer tight oil and shale oil.

Key words: Dongpu Depression, oil-rich depression, coalbed methane, accumulation model, enrichment patterns

CLC Number:

P618.130.2

XU Tianwu, ZHANG Hong’an. Analysis of oil and gas distribution and exploration potential in oil-rich depression: Taking Dongpu Depression as an example[J]. Earth Science Frontiers, 2024, 31(6): 368-380.

Figures/Tables 13

Fig.1 Distribution of oil and gas fields in the Dongpu Depression of the Bohai Bay Basin

Fig.2 Relationship between proven oil and gas resources and remaining oil and gas resources in different areas of the Dongpu Depression

Fig.3 Scatter plots of oil-rich depression γ-wax-Pr/Ph (a) and gamma wax/C30 hopane-TOC (b)

Fig.4 Distribution characteristics of carbon isotope in crude oil in the Dongpu Depression

Fig.5 Distribution characteristics of crude oil of different genetic types in the northern Dongpu Depression

Fig.6 Classification of oil and gas systems in the oil-rich area of the Dongpu Depression

Fig.7 Distribution of proven reserves from different strata relative to hydrocarbon expulsion centers in the Dongpu Depression

Fig.8 Distribution of hydrocarbon accumulation sequences in the Wenliu area (oil-rich area) of the Dongpu Depression

Fig.9 Distribution of pressure coefficient and overpressure relationship in the third member of the Shahejie Formation in the Dongpu Depression

Fig.10 Composition of microscopic components of coal, dark mudstone, and carbonaceous mudstone in the Upper Paleozoic of the Dongpu Depression

Fig.11 Coal gas generation rates in different regions nationwide (a) and in the Dongpu Depression (b). Adapted from [18].

Fig.12 Overlay of hydrocarbon generation intensity of Upper Paleozoic coal-bearing source rocks in the Dongpu Depression

Fig.13 Hydrocarbon accumulation models of coalbed methane in the Dongpu Depression

References 21

[1]	余海波, 程秀申, 徐田武, 等. 东濮凹陷古近系构造特征及其对油气成藏的控制作用[J]. 油气地质与采收率, 2021, 28(3): 42-52.
[2]	彭君, 孙宁亮, 鹿坤, 等. 东濮凹陷古近系沙河街组页岩油储层岩石学及微观孔隙结构特征[J]. 地学前缘, 2023, 30(4): 128-141. DOI
[3]	高红灿, 郑荣才, 肖应凯, 等. 渤海湾盆地东濮凹陷古近系沙河街组盐岩成因: 来自沉积学和地球化学的证据[J]. 石油学报, 2015, 36(1): 19-32. DOI
[4]	杜海峰, 于兴河, 陈发亮. 河南省东濮凹陷古近系沙河街组沙三段盐岩沉积特征及其石油地质意义[J]. 古地理学报, 2008, 10(1): 53-62.
[5]	刘景东, 蒋有录, 谈玉明, 等. 渤海湾盆地东濮凹陷膏盐岩与油气的关系[J]. 沉积学报, 2014, 32(1): 126-137.
[6]	孙镇城, 杨藩, 张枝焕, 等. 中国新生代咸化湖泊沉积环境与油气生成[M]. 北京: 石油工业出版社, 1997.
[7]	郑绵平. 中国盐湖资源与生态环境[J]. 地质学报, 2010, 84(11): 1613-1622.
[8]	HAMMER U T. Saline lake ecosystem of the world[M]. Dordrecht: Junk Publishers, 1986.
[9]	ZHENG M P. Resources and eco-environmental protection of salt lakes in China[J]. Environmental Earth Sciences, 2011, 64(6): 1537-1546.
[10]	MERNAGH T P, BASTRAKOV E N, JAIRETH S, et al. A review of Australian salt lakes and associated mineral systems[J]. Australian Journal of Earth Sciences, 2016, 63(2): 131-157.
[11]	金强, 朱光有. 中国中新生代咸化湖盆烃源岩沉积的问题及相关进展[J]. 高校地质学报, 2006, 12(4): 483-492.
[12]	张洪安, 徐田武, 张云献. 东濮凹陷咸化湖盆优质烃源岩的发育特征及意义[J]. 断块油气田, 2017, 24(4): 437-441.
[13]	王金萍, 黄泽贵, 张云献, 等. 东濮凹陷优质烃源岩的岩性特征及宏观展布规律[J]. 断块油气田, 2018, 25(5): 549-554.
[14]	张洪安, 李素梅, 徐田武, 等. 东濮凹陷北部盐湖相原油特征与成因[J]. 现代地质, 2017, 31(4): 768-778.
[15]	徐田武, 张洪安, 李继东, 等. 渤海湾盆地东濮凹陷盐湖相成烃成藏特征[J]. 石油与天然气地质, 2019, 40(2): 248-261.
[16]	胡朝元. “源控论” 适用范围量化分析[J]. 天然气工业, 2005, 25(10): 1-3.
[17]	庞雄奇, 李丕龙, 金之钧, 等. 油气成藏门限研究及其在济阳坳陷中的应用[J]. 石油与天然气地质, 2003, 24(3): 204-209.
[18]	戴金星, 戚厚发, 宋岩, 等. 我国煤层气组份、碳同位素类型及其成因和意义[J]. 中国科学: B辑, 1986(12): 1317-1326.
[19]	戴金星. 各类烷烃气的鉴别[J]. 中国科学: B辑, 1992(2): 185-193.
[20]	沈平, 徐永昌, 王先彬, 等. 气源岩和天然气地球化学特征及成气机理研究[M]. 兰州: 甘肃科学技术出版社, 1991.
[21]	徐永昌, 沈平, 刘文汇, 等. 一种新的天然气成因类型: 生物—热催化过渡带气[J]. 中国科学: B辑, 1991(9): 1113-1119.