«Geology, geophysics and development of oil and gas fields»

Lithological characteristics and reservoir properties of basal beds sandstones of the Lower Eocene in the southeast of Jiyang depression, Bohai Bay Basin, China

UDC: 553.98(510):552.5
DOI: 10.33285/2413-5011-2022-1(361)-22-27

Authors:

¹ Lomonosov Moscow State University, Moscow, Russia

Keywords: sandstones, basal strata, sandstone reservoirs, pores, cements, porosity, permeability, Jiyang depression

Annotation:

Jiyang depression is located in the southeast of the Bohai Bay Basin, its area of about 29⋅103 km2. It consists of several smaller depressions, the most famous of which is the Dongying depression, where many large oil and gas reservoirs have been found. Jiyang depression was formed in the Early Eocene as a result of powerful tectonic movements along the largest in the region system of Tanlu faults. Basal strata of continental and lacustrine sediments, mainly composed by sandstones, inter-bedded by interlayers and clay packs and painted in red, brown and gay colors, got the name of a red-color formation, which is mainly composed by Lower Shahejie-4 and Kongdian-1 formations. Sandstones in basal red-colored sediments of the south-eastern area of strata Jiyang depression are represented by arkoses, quartz-feldspar and feldspar-quartz graywackes. The quartz content of sandstone in Kongdian-1 formation gradually increases to 58.2 % from bottom to top. The sandstones in the lower part of Shahejie-4 formation have rather small content of debris, what is probably caused by tectonic movements activity in the region. Analysis of the core materials obtained during drilling in recent years as well as the rocks study in thin sections allowed revealing presence of various types of cements in the sandstones. Herewith, the most common is the carbonate cement, siliceous, pyrite, hematite, gypsum, anhydrite and other cements are also observed. The reservoir properties of sandstones in the red-colored sediments of the Lower Eocene in the southeastern part of the Jiyang depression are determined by the presence of both pores and cracks. They are characterized by good porosity and permeability, which is mainly due to the existence of open, large and small pores inherited from both the sedimentation stage and the stages of early and late diagenesis. Due to the existence of a large number of pores and cracks, especially the connected pores formed in the stage of sedimentation and the middle and late stages of diagenesis, the sandstone in the study area has better reservoir performance.

Bibliography:

1. Konyukhov A.I., Chen’ Syaotszyun’. Litologiya i usloviya formirovaniya paleogenovykh otlozheniy vo vpadine Dunin (basseyn Bokhayskogo zaliva, KNR) // Litologiya i poleznyye iskopayemyye. – 2007. – № 6. – S. 613–636.
2. Sedimentary characteristics and model of red beds – gypsum salt beds of the Paleogene in Dongying Sag, Jiyang Depression / Cao Yingchang, Wang Jian, Gao Yongjin, Liu Huimin, Tang Dong // Journal of palaeogeography. – 2011. – №13(4). – Pр. 376–386.
3. Zhu Xiaomin, Wang Yingguo, Zhong Dakang. Main controlling factors of deposition, drocarbon accumulation and exploration potential of Paleogene red beds in Jiyang depression // Acta Petrolei Sinica. – 2012. – № 33(1). – Pр. 63–70.
4. Vosstanovleniye paleofatsial’nykh usloviy sredy osadkonakopleniya krasnotsvetnykh otlozheniy eotsena vo vpadine Dunin i ego geologicheskoye znacheniye / Li Tszyan, Sunguotszi, Gaoyuntszin, Yan Syuyetszyun’ // Neftyanaya geologiya i razrabotka Datsin. – 2013. – № 32(2). – S. 85–95 (na kitayskom yazyke; 李继岩，宋国奇, 高永进, 杨学君. 东营凹陷始新统红层古沉积环境恢复及其地质意义. 大庆石油地质与开发, 2013. – 32(2). – 85–95).
5. Kollektorskiye svoystva i kontroliruyushchiye ikh faktory krasnotsvetnykh otlozheniy yarusa Kondyan’ na vostoke vpadiny Dunin, basseyn Bokhayvan’ / Don Dav•ey, Li Tszyan, Van Saoley, Shan lin’, Lyu Tszyan’ // Vestnik kitayskogo neftyanogo un-ta. – 2017. – № 41(5). – S. 20–29 (na kitayskom yazyke; 董大伟，李继岩，王晓蕾, 商琳, 刘建. 渤海湾盆地东营凹陷东部孔店组红层储层特征及控制因素. 中国石油大学学报, 2017. – 41(5). – 20–29).
6. Wang Jian, Cao Yingchang, GaoYongjin. Pore types and secondary pore evolution of Paleogene reservoir in the Jiyang Sag // Acta Geologica Sinica. – 2013. – № 81(2). – Pр. 197–205.
7. Zou Caineng, Tao Shizhen, Zhou Hui. Genesis, classification and evaluation of diagenetic facies // Petroleum Exploration and Development. – 2008. – № 35(5). – Pр. 526–540.
8. Chzhan Shan’v•en, Yuan’ Tszin, Suyf•enguy. Mnozhestvennyye diageneticheskiye usloviya i modeli evolyutsii kollektorov svity Shakh•etsze-4 na severe vpadiny Dunin // Nauka o zemle. – 2008. – № 43(3). – S. 576–587 (na kitayskom yazyke; 张善文，袁静，隋凤贵. 东营凹陷北部沙河街组四段深部储层多重成岩环境及演化模式. 地质科学, 2008. – 43(3). – 576–587).
9. Li Zhong, Han Denglin, Chou Jianfeng. Diagenesis systems and their spatio-temporal attributes in sedimentary basins // Acta Petrologica Sinica. – 2006. – № 22(8). – Pр. 2151–2164.