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Geochemical characteristics and genetic types of deep natural gas in dehui fault depression, Songliao basin
Published in Ahmad Safuan Bin A Rashid, Junwen Zhang, Advances in Mineral Resources, Geotechnology and Geological Exploration, 2023
The Dehui fault depression is located in the middle of the eastern fault depression in the southeastern uplift area of the southern Songliao Basin, with an area of about 4000 km2 (Figure 1). The Dehui fault depression belongs to the secondary structural unit and can be divided into Xiaohelong-Buhai structural belt, Xiaohelong subsag, Central anticline structural belt, Nong’andong subsag, and Nong’an-Wanjinta structural belt. The same as the entire southeastern uplift area and even the entire Songliao Basin, the Dehui fault depression has an obvious composite double-layer structure of fault-depression (Di 2007). The study area mainly develops Jurassic, Cretaceous, Neogene, and Quaternary strata. On this basis, three sets of source rocks are developed in the study area, whose lithology includes dark mudstone, carbonaceous mudstone, and coal. Reservoirs include sedimentary rocks and volcanic rocks. The sedimentary rock reservoirs are silt-fine sandstone and glutenite, and the volcanic rock reservoirs are volcanic rocks and pyroclastic rocks. At present, the discovered oil and gas reservoirs in the Dehui fault depression are dominated by structural traps, including fault block traps, fault nose traps, and anticline traps.
Significance of Reservoir Health and Its Impact on Reservoir Performance
Published in Ashok K. Pathak, Petroleum Reservoir Management, 2021
The oil rate has a direct and more meaningful correlation, better than reservoir pressure, with reservoir health. Daily oil rates on a reservoir and well-by-well basis are monitored continuously to protect the cash flow. These readings are plotted on a graph to determine if there is a clear and consistent trend. In the depletion drive reservoir case, a downward trend in oil rate described as “decline rate” is associated with a fall in reservoir pressure and energy loss due to a rapid increase in producing GOR. However, in other drive mechanisms, the rate decline may be accompanied by an increase in producing GOR or water cut or both. Such situations demand shutting-in high GOR or high water cut wells to conserve reservoir energy. This loss of production due to the temporary shut-in of wells may sometimes be compensated by other producers in the same layer or fault block.
Geology
Published in Ronald C. Chaney, Marine Geology and Geotechnology of the South China Sea and Taiwan Strait, 2020
The Spratly Islands consists of 14 islands ranging in area from 0.4 to 46 ha with an additional 600 coral reefs. A list of the various individual islands is presented in Table 2.4. The largest island is Taiping Island, which is occupied by the Republic of China (ROC). These islands consist of a combination of reefs, banks, and shoals that are built of biogenic carbonate on the higher crests of major submarine horsts. A horst is an uplifted fault block. These horsts are part of a series of parallel and en echelon half-grabens and rotated fault blocks. Their long axis defines linear trends that are parallel to magnetic anomalies exhibited by the oceanic crust. The rotational block faulting is a result of tectonic plates stretching apart. The horsts, grabens, rotated fault blocks, and the rock forming the base consist of stretched and subsided continental crust. This rock is composed of Triassic (220 Ma), Jurassic (192 Ma), and Cretaceous (135 Ma) strata. These rocks include calc-alkalic extrusive igneous rocks, intermediate to acid intrusive igneous rocks, sandstorms, siltstones, dark green claystones, and metamorphic rock. That includes both biotite-muscovite-feldspar-quartz highly complex rock and garnet-mica schists (Wikipedia, 2020).
Characteristics of fluid potential and the division of hydrocarbon migration and accumulation units in the Nangong Sag, Bohai Bay Basin, China
Published in Petroleum Science and Technology, 2022
Tianshun Liu, Wenlong Ding, Zhanwen Yu, Jingtian Li, Sicheng Wang, Xu Zhou, Xiaoyun Cheng
Based on the distribution characteristics of fluid potential, combined with the development stratigraphic location and plane distribution characteristics of high-quality source rocks, the distribution location of favorable reservoirs and structural traps, and the dominant migration channels of hydrocarbon, the hydrocarbon generation and accumulation modes of migration and accumulation unit III and migration and accumulation unit IV in Nangong Sag are preliminarily put forward (Figure 6b). The Cenozoic high-quality source rock is developed in Es3, which is banded on the plane and parallel to the long axis of the sag. High quality reservoirs are vertically developed in Es3 and Es2 and horizontally distributed in the western slope. Structural traps are mainly anticline traps and fault block traps. Fault block traps are mainly located in the western slope belt and formed in Eocene and Oligocene. Anticline traps are mainly located in the Juanzizhen anticline structural belt and the Qijizhen anticline structural belt, which were mainly formed in Oligocene. The transport system is mainly fault, unconformity, connected sand body and its composite type. There are two main Pool-forming modes in Nangong Sag.
Characteristics of fluid potential and division of hydrocarbon migration and accumulation units in the Shijiazhuang Sag
Published in Petroleum Science and Technology, 2021
Chen Liang, Wenlong Ding, Jia yi Zhou, Ruyue Wang, Ruiqiang Yang
Located in the southwest of the study area, as shown in seismic line 89217 (Figure 1C) the faults are relatively developed, mainly developed in the high-angle NNE-trending normal faults. Due to the fault activity, the faults are not completely sealed, so oil and gas can migrate through the fault plane and partly play the role of plugging. The main types of traps are fault nose, fault block, fault anticline trap and lithologic reservoir. However, this migration and accumulation unit deviates from the mainstream line of oil and gas migration, which is not conducive to oil and gas migration. Even if there is a small amount of oil and gas migration, most of the oil and gas will escape in the long-distance migration process, which is not conducive to oil and gas accumulation (Figure 8A).
Genesis and origin of natural gas in the Beidagang structural belt of Dagang oilfield
Published in Petroleum Science and Technology, 2019
Jungang Lu, Ruopeng Lin, Chun Liu, Yong Li, Zhenglu Xiao, Qingbo He
Beidagang structural belt located at the north-central of huanghua basin, the north and south are depressed, belong typical concave mid - rise. The north of the Beidagang structural belt is Banqiao sag, south and east of it is Qikou sag (Figure 1).The vertical distribution of oil and gas in this area has the characteristics of multi-age and multi-layer. Up to now have find Minghuazhen Formation (Nm), Guantao Formation (Ng) of Neogene and Dongyin Formation (Ed), Shahejie Formation (Es) of paleogene and Paleozoic ordovician system, those are all oil-bearing horizons. Neogene’s proven reserves account for about 30% of total reserves, paleogene’s proven reserves account for about 70% of total reserves, ordovician system has less natural gas. Now, this area has find Banbei, Banzhong, Bannan, Baishuitou, Tangjiahe, Gangdong, Madong, Maxi, Qianmiqiao oil and gas fields. There are various types of oil and gas reservoirs in this area, including anticline, fault nose, fault block, lithology and buried hill (Lu et al. 2015, 2017; Su et al. 2018).