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The Dongpu depression, like other depressions in the Bohai Bay Basin, is characterized by overpressure, however, the published studies have not clearly given the overpressure formation mechanism and paleo-pressure evolution history in the Dongpu depression. In addition, the current researches are mainly focused on the northern Dongpu depression, wh...
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... exploration to have a research of the overpressure origins in oil and gas bearing basins, especially in the basins with significant heterogeneity of hydrocarbon distribution. The Dongpu depression, located in the Bohai Bay Basin, North China, is divided into the northern part and the southern part by the NW trending blind strike-slip fault (Fig. 1). The northern part has 90% of the total petroleum reserves, but the southern part has only 10%. The salt rocks that are thought to represent the evaporation of arid environment are all distributed in the northern part, which are the most direct evidence of the sedimentary environment differentiation in the Dongpu ...
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... (~18 km) and broad in the south (~62 km), with a coverage area of about 5 300 km 2 ( Lyu and Jiang, 2017). It is divided from Luxi uplift by Lanliao fault in the east, overlaps Neihuang uplift in the west, faces the Kaifeng depression across Lankao uplift in the south, and is connected with the Xinxian depression by Maling fault in the north (Fig. 1). Within the depression, four sub-structural units are divided from west to east, namely western slope belt, western sag belt, central uplift belt, and eastern sag belt. They all have the same tectonically NNW-trending as the depression (Fig. 1). Besides the NNE-trending faults, there are also many NWW-trending adjusting faults ...
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... Lankao uplift in the south, and is connected with the Xinxian depression by Maling fault in the north (Fig. 1). Within the depression, four sub-structural units are divided from west to east, namely western slope belt, western sag belt, central uplift belt, and eastern sag belt. They all have the same tectonically NNW-trending as the depression (Fig. 1). Besides the NNE-trending faults, there are also many NWW-trending adjusting faults activated at different times. Some NWW-trending adjusting faults comprise an adjusting fault belt cutting through Gaopingji-Qiaokou-Baimiao area and keep active during the whole Paleogene. They are considered as the boundary between the northern part ...
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... are also many NWW-trending adjusting faults activated at different times. Some NWW-trending adjusting faults comprise an adjusting fault belt cutting through Gaopingji-Qiaokou-Baimiao area and keep active during the whole Paleogene. They are considered as the boundary between the northern part and the southern part of the Dongpu depression ( Fig. 1). Many properties are proven to be different between the two parts. In addition to the amount of petroleum resources and the salt rock distribution, the northern part is characterized by a large amount of organic matter and type I and II kerogen, whereas the southern part has a relatively small content of organic matters and type II ...
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... developed in the Es 1 , Es 3 and Es 4 in the northern part. Horizontally, Salts rocks are mainly deposited in the Weicheng, Liutun, Hubuzhai, Wenliu and Qianliyuan areas, covering both the western sag belt and the central uplift belt, with partially on the western slope belt and the eastern sag belt. To the south, they disappear near the boundary (Fig. ...
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... burial histories of each well are shown in Figs. 9 and 10, while the hydrocarbon generation histories of two wells (PS18 and L1) located in the northern and southern parts respectively are shown in Figs. 11c and 12c. Well PS18 is located in the western sag belt of the northern part of the Dongpu depression, whereas Well L1 in the same sag belt of the southern part. Both of them have surface temperature of 20 ºC. The geothermal gradients in Well PS18 are from 2.8-3.5 ºC/100 m, ...
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... temperature, but it has a close to one pressure coefficient, which means a normal pressure condition, then it must be trapped during the uplifting stage; on the contrary, if it has a very high pressure coefficient, it must be trapped before the uplifting stage. These dating concerns are also applied to the Minghuazhen uplifting stage (Figs. 9 and ...
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... inclusion pressure recovery and chronological results provide us with a history of pressure evolution of nearly 45 million years. The paleo-pressure evolution in the northern Dongpu depression has usually been divided into three stages ( Liu et al., 2010). However, in this study, we propose the (Fig. 11a). The main factor causing the pressure re-release stage is the uplifting at the end of the Minghuazhen Formation. The inclusion records in different host minerals jointly reveal the pressure evolution process. As shown in Fig. 11a, Quartz overgrowth takes the lead in trapping the oil inclusion at 41.9 Ma with pressure coefficient of ...
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... depression has usually been divided into three stages ( Liu et al., 2010). However, in this study, we propose the (Fig. 11a). The main factor causing the pressure re-release stage is the uplifting at the end of the Minghuazhen Formation. The inclusion records in different host minerals jointly reveal the pressure evolution process. As shown in Fig. 11a, Quartz overgrowth takes the lead in trapping the oil inclusion at 41.9 Ma with pressure coefficient of 1.24. Oil inclusions in fractures come to the second, whose whole pressure evolution is recorded most completely and apparently, the record of the oil inclusions starts from 38.3 Ma with pressure coefficient of 1.14, increases to ...
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... the pressure evolution is recorded by oil inclusions, there is a close internal relationship between pressure evolution and oil charging history. As shown in Fig. 11b, 4 U in the sequence, it can be concluded that the oil charging has the order of sag first and the uplift, lower part first and then upper ...
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... paleo-pressure evolution in the southern Dongpu depression is analogous to that in the northern part. It can also be divided into four stages (Fig. 12a). The trapping sequence shows quartz overgrowth comes the first, and follows CC1, fracture, feldspar and CC2. The oil inclusions in fractures cover almost the whole evolution (Fig. 12a). The trapping sequence which generally matches the paragenesis indicates the results is reliable. The trapping sequence of oil inclusions in different ...
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... paleo-pressure evolution in the southern Dongpu depression is analogous to that in the northern part. It can also be divided into four stages (Fig. 12a). The trapping sequence shows quartz overgrowth comes the first, and follows CC1, fracture, feldspar and CC2. The oil inclusions in fractures cover almost the whole evolution (Fig. 12a). The trapping sequence which generally matches the paragenesis indicates the results is reliable. The trapping sequence of oil inclusions in different areas and formations do not show a clear order from sag to uplift or from bottom to top (Fig. 12b), which may result from insufficient fluid inclusion ...
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... CC1, fracture, feldspar and CC2. The oil inclusions in fractures cover almost the whole evolution (Fig. 12a). The trapping sequence which generally matches the paragenesis indicates the results is reliable. The trapping sequence of oil inclusions in different areas and formations do not show a clear order from sag to uplift or from bottom to top (Fig. 12b), which may result from insufficient fluid inclusion ...
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... in Fig. 11b from left to right proves this assumption. This dot has a pressure coefficient over 1.2, which indicates an overpressure condition, and it is trapped at 41.9 Ma, much earlier than the time of first hydrocarbon generation rate peak (Fig. 11c), with a burial depth of less than 2 000 m ( Fig. 9, PS7). However, the hydraulic fractures ...
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... in Fig. 11b from left to right proves this assumption. This dot has a pressure coefficient over 1.2, which indicates an overpressure condition, and it is trapped at 41.9 Ma, much earlier than the time of first hydrocarbon generation rate peak (Fig. 11c), with a burial depth of less than 2 000 m ( Fig. 9, PS7). However, the hydraulic fractures (Fig. 11d), which are considered as a main evidence of disequilibrium compaction ( Luo et al., 2015), appear after the intense hydrocarbon generation peak (Fig. 11c), so it is still difficult to clarify the overpressure mechanism at the end of ...
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... in Fig. 11b from left to right proves this assumption. This dot has a pressure coefficient over 1.2, which indicates an overpressure condition, and it is trapped at 41.9 Ma, much earlier than the time of first hydrocarbon generation rate peak (Fig. 11c), with a burial depth of less than 2 000 m ( Fig. 9, PS7). However, the hydraulic fractures (Fig. 11d), which are considered as a main evidence of disequilibrium compaction ( Luo et al., 2015), appear after the intense hydrocarbon generation peak (Fig. 11c), so it is still difficult to clarify the overpressure mechanism at the end of Stage I. The paleo-geomorphological reconstruction indicates that Pucheng area is always an uplift ...
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... is trapped at 41.9 Ma, much earlier than the time of first hydrocarbon generation rate peak (Fig. 11c), with a burial depth of less than 2 000 m ( Fig. 9, PS7). However, the hydraulic fractures (Fig. 11d), which are considered as a main evidence of disequilibrium compaction ( Luo et al., 2015), appear after the intense hydrocarbon generation peak (Fig. 11c), so it is still difficult to clarify the overpressure mechanism at the end of Stage I. The paleo-geomorphological reconstruction indicates that Pucheng area is always an uplift during Es 4 U -Es 3 U , whereas Qianliyuan area is a sub-sag from Es 4 U -Es 3 U ( Yu et al., 2018;Xu, 2018). If the overpressure was mainly caused by ...
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... is no salt rock distribution in the southern Dongpu depression, so the disequilibrium compaction overpressure is not likely to happen as the fractures appear throughout the whole process. However, there still are two overpressure stages. The overpressure formation time is consistent with the hydrocarbon generation time (Fig. 12b), which is very direct evidence that the overpressure is caused by hydrocarbon ...
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... by overpressure; however, in Wenmingzhai, Machang, and Sanchunji area, the pressure coefficients are all below 1.2 (Fig. 8). It indicates that the salt rock distribution plays an important role in overpressure preservation as there is not any salt rock distribution in these areas. In Qiaokou and Baimiao area, there is no salt rock distribution (Fig. 1), but DST data show strong overpressure below 3 080 m (Fig. 8), which indicates that the fault closure is considered as another factor that prevent pressure loss ( Jiang et al., 2016). It is obvious that the tectonic movements are the main factor that caused pressure release. The pressure release stage and rerelease stage are ...
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Citations
... Based on what was said above, fluid inclusion PVTX modeling is the sole method to determine the pressure of hydrocarbon-associated diagenetic fluids in a complex geodynamic framework of a sedimentary basin (Bahnan et al., 2021b). Therefore, it has been applied in a number of studies targeting hydrocarbon reservoirs around the globe, such as the Gulf Cost (USA) (Mclimans, 1987), the Appalachian Plateau (Evans, 1995), the South Brent petroleum system in the northern North Sea (Tseng and Pottorf, 2002), the Níspero field (Mexico) (Bourdet et al., 2010), the Jabiru oil field in the Timor Sea (Australia) (Bourdet et al., 2012), the southern Piceance Basin (USA) (Fall et al., 2012), the Lacq gas field (France) (Bahnan et al., 2020(Bahnan et al., , 2021a, the Bohai Bay Basin (China) (Liu et al., 2023a) and many others (Bodnar, 1990;Aplin et al., 2000aAplin et al., , 2000bThiéry et al., 2002;Liu et al., 2003Liu et al., , 2022Tseng and Pottorf, 2003;Munz et al., 2004;Ferket et al., 2011;Ni et al., 2016;Chang et al., 2019;Su et al., 2019Su et al., , 2023Ping et al., 2020;Wang et al., 2020bWang et al., , 2022 for the purpose of obtaining an insight into the fluid history of the reservoir. Recent DBRs explorations in the Dengying Formation (Ediacaran age) in the northern slope (Penglai area) of the central paleohigh of the Neoproterozoic Sichuan Basin (SW China) (Dai et al., 2021;Zhang, 2022) are reaching deeper strata (more than -6000 m). ...
... Overpressure is considered in a reservoir when the pore pressure is 1.2 times of the hydrostatic pressure in China (Guo et al., 2010;Cheng and Fu, 2022;Liu et al., 2022). Therefore, we can conclude that only fluid episodes #1 and #2 in dolomite 2 and the present-day conditions of the reservoir are at normal pressure regime, whereas the rest of the identified fluid episodes are all in overpressure settings (Fig. 9). ...
... Note that from fluid episode #4 to fluid episode #5, the pressure stays relatively constant with temperature and hydrostatic pressure increasing, indicating a pressure leakage period between around 220 and 160 Ma. Pressure release can be caused by basin uplifting, where seal rock integrity failure is caused by tectonic movement (Ohm et al., 2008;Liu et al., 2022). Whereas, the pressure of fluid reaching the lithostatic pressure can also induce occasional caprock integrity failure (Wang et al., 2020a;Liu et al., 2023a). ...
... The third member of the Shehejie Formation (Es 3 ) is the most petroliferous and the most promising section for shale oil/gas exploration (Wang et al., 2020a;Wang et al., 2018;Wang et al., 2015a). A fluid inclusions study suggests that oil charging in the north part of the depression started as early as 42 Ma, which is around 17 Ma earlier than in the south (Liu et al., 2022a). Numerous studies have pointed out that the paleoenvironment and kerogen type is the key aspect that determines the higher petroleum abundance in the north of the depression compared to the southern part because the northern part contains type I and type II 1 kerogens (Tang et al., 2020;Wang et al., 2020c;Wang et al., 2020d;Zheng et al., 2022). ...
... (3) the thermal-subsidence stage from the deposition of Ng to Nm; and (4) the reactive stage, including the uplifting at the end of the Minghuazhen deposition until the present day (Liu et al., 2022a). The Dongpu Depression is divided into the north and south by a N-E trending strike-slip fault that cuts across the Gaopingji, Qiaokou, and Baimiao areas ( Fig. 1B) (Liu et al., 2023a). ...
The third member of the Paleogene Shahejie Formation (Es3) in the Dongpu Depression, China, was studied to interpret its paleoenvironment through a series of trace element proxies, to reveal paleosalinity conditions, to elucidate on the hydrological conditions of the paleolake using carbon and oxygen stable isotopes, and to investigate the effects of paleoredox conditions on organic matter preservation. Most of the redox-sensitive proxies, such as U/Th, V/Cr, Ni/Co, Uauth, (Cu + Mo)/Zn, Cu/Zn, Th/U, and V/Sc, indicate that the Es3 was deposited under predominantly oxic and oxic/suboxic conditions, while V/(V + Ni) and U and previous studies suggested that the formation was deposited under mainly anoxic conditions. Oxygen levels agreed with the trace element ratios and showed a decrease from the lower to the upper part of the Es3 and an increase in paleoproductivity in the same direction. Salt rocks interbedded within the formation were shown to have overall lower oxygen levels than their neighboring organic-rich layers, black shale, and mudstone intervals, this have likely altered the paleoredox proxies to oxygen consumption. Although Sr/Ba values point to a saline lake environment, the relative fluctuations seen suggests that the above ratio is not an appropriate indicator of paleosalinity in salt-bearing strata and that the variations in paleoredox conditions in the formation are not a function of paleosalinity. Based on the negative δ13C and δ18O stable isotopic values, it is inferred that the shales in the Es3 were deposited in a hydrologically open lake environment. However, the presence of palynomorphs such as dinoflagellate cysts that are typically found in middle to outer neritic and open marine environments reinforces the assumption of a sea level transgression and inundation of the lake basin and mixing with freshwater algae and rare terrigenous phytoclasts such as cuticles, wood fragments, and suberin. The higher TOC content and lower oxygen levels in the upper Es3 have contributed to greater OM presentation in the absence of any variations in salinity or freshwater influx. The study also demonstrates that many of the paleoredox proxies and thresholds established are not valid to properly characterize certain formations deposited in lacustrine lake paleoenvironments such as the Shahejie, thus their applicability in certain situations must be re-evaluated.
... The Dongpu Depression is characterized by a rift basin with developed faults of different sizes. The depression is divided into 4 main tectonic zones, which are the western slope belt, western sag, central uplift belt [49]). and eastern slope belt from east to west (Fig. 1b). ...
... The main caprocks are low-permeability mudstone and gypsum salt in Es 3 and Es 2 [47,48]. To conclude, there are multiple petroleum systems and hydrocarbon accumulating units consisting of different combinations of source rocks, reservoirs, and caprocks [48,49]. ...
... The Dongpu Depression experienced three main tectonic events from the Palaeogene period to the present. The whole Palaeogene period was dominated by a rifting stage with frequent fault movement [46,49]. Following deep burial of the sediments, the source rocks began to generate hydrocarbons. ...
... A large number of studies have been carried out for understanding the factors affecting hydrocarbon enrichment within the depression using organic petrography and geochemical methods Yan et al., 2019;Hu et al., 2021b;Zheng et al., 2022) since shale oil exploration began in the Dongpu Depression (Wang et al., 2015). Furthermore, fluid inclusion analyses have also been conducted, showing a variety of fluorescence colors with complex charging history (Jiang et al., 2016;Liu et al., 2022b). Although, some oil-source and oil-oil correlations were achieved in the area (Ke et al., 2020;Ke et al., 2022), the thermal maturity distribution of oils in the depression has never been systematically understood and compared. ...
... (2) the uplifting (erosion) stage, caused by the Dongying movement, at the end of deposition of the Ed; (3) the thermal-subsidence stage from the deposition of the Nm to Ng; and (4) the reactive stage, corresponding to the second phase of the Himalayan movement, from the end of the Nm deposition to present-day ( Fig. 2) (Liu et al., 2022b). Moreover, some scholars subdivide the rifting stage into four substages as: (1) the initial rifting substage during the deposition of the Es 4 ; (2) the main (intense) rifting substage during the deposition of the Es 3 ; (3) the post rifting substage during the deposition of Es 2 and Es 1 ; and (4) the subsidence substage (rifting termination) during the deposition of the Ed (Tang et al., 2020;Jiang et al., 2021;Zhu et al., 2021). ...
... The Shahejie Formation in the Dongpu Depression is characterized by multiple sets of source rocks and reservoirs interbedded (Zhu et al., 2021). Each layer of reservoir could have been charged simultaneously by oils from different source rocks that were at different burial depth and thermal maturities Liu et al., 2022b). Therefore, variation in the fluorescence of oil inclusions in reservoirs does not exactly represent oil generation and expulsion episodes but only the presence of oil with various thermal maturities or densities (API). ...
The Dongpu Depression is an important petroliferous basin in China with abundance of hydrocarbons. The fluorescence characteristics of inclusion oils and their relationship with the present-day produced crude oils have never been systematically studied in the basin scale. This knowledge can further clarify ambiguities in petroleum system modeling and support exploration efforts in the area. To this end, core samples and crude oils were collected from the Shahejie Formation (Paleogene) in the Dongpu Depression to perform fluorescence and infrared spectroscopy from the source rock and the reservoir. Results show that the fluorescence characteristics of oil inclusions in the source rocks are consistent with oil inclusions in the reservoirs in the northern part of the depression, showing blue, green, yellow and orange fluorescence colors; whereas orange fluorescence is absent in the southern part in inclusions. Moreover, lack of a robust relationship between λmax and QF-535 suggests crude oils have gone through secondary alterations towards becoming heavy oil. Herein, comparison between the IR (CH2/CH3) and fluorescence parameters (λmax and QF-535) illustrates that CH2/CH3, although is suitable for organic matter thermal maturity assessment, cannot be directly applied to the expelled oils. Moreover, the occurrence of orange fluorescing oils in the horsts can be accounted for a higher hydrocarbon potential in these areas. Additionally, establishing a clear relationship between fluorescence and IR parameters failed in certain strata or structural unit, proving a complex tectonic setting of the depression. Overall, this study reveals the geologic nature of the Dongpu Depression is very complicated, which means additional analytical studies to resolve the oil-source correlation problem, in particular, would be necessary.
... The fluorescence color of oil inclusions is widely used to indicate the maturity of the inclusion oil because it is measurable [31][32][33][34]. With increasing maturity, the fluorescence color of oil inclusions changes from yellow to blue [35,36]. ...
In recent years, newly discovered ultra-deep fault-karst reservoirs in the Shunbei area of the Tarim Basin have greatly increased the prospectivity of the basin and become a hotspot for further hydrocarbon exploration. In this study, the diagenetic sequences of the Lower-Middle Ordovician reservoir were established through observation of thin sections under transmitted light, reflected light, and cathode luminescence. The hydrocarbon charge history in the Shunbei area was reconstructed and associated with a series of diagenetic events using fluid inclusion microthermometric measurements combined with one-dimensional basin modeling. The results show that the Shunbei area has experienced three hydrocarbon charging episodes in total, in the late Caledonian, late Hercynian, and late Himalayan. Finally, the relationship between measured QF-535 factors and the API gravity of crude oil was used to quantify the level of contribution of each of the petroleum charging episodes to the No. 1, No. 5, and No. 7 fault zone reservoirs. The contribution of early hydrocarbon charging episodes gradually increases from west to east in the Shunbei area. This increase was driven by different tectonic events throughout geological history and the subsequent evolution of paleo-structural patterns. This study has a significant impact on marine carbonate reservoir evaluation in strike-slip fault zones in China.
... Oil maturity has been widely investigated in the Shahejie Formation in the Dongpu Depression, with orange, yellow, green, and blue fluorescing oil inclusions detected in the reservoirs (Jiang et al., 2016;Liu et al., 2020bLiu et al., , 2020c. However, fractionation of oil during migration, which is a common phenomenon (Sajgó et al., 1983;Yamamoto, 1992), has rarely been considered in these studies performed in that area. ...
... However, fractionation of oil during migration, which is a common phenomenon (Sajgó et al., 1983;Yamamoto, 1992), has rarely been considered in these studies performed in that area. A possible reason is that there has not been any record of fractionation evidence in sandstone samples of the Dongpu Depression (Jiang et al., 2016;Liu et al., 2020bLiu et al., , 2020cPing et al., 2020). Though, in this study, we realized that the fluorescence color of oil inclusions gradually changes along a healing fracture, indicating the oil chemical composition variation as a result of fractionation during migration (Fig. 4G). ...
... Several published papers have reported the pressure evolution of the Dongpu Depression via basin and fluid inclusion modeling (Sun et al., 2013;Luo et al., 2016;Liu et al., 2020aLiu et al., , 2020bPing et al., 2020). These studies suggested an overpressure accumulation stage (50-27 Ma) caused by disequilibrium compaction during rapid subsidence as well as hydrocarbon generation, followed by an overpressure release stage owing to the Dongying movement (uplifting from 27 to 17 Ma). ...
Salt rocks are widely distributed in the Paleogene strata of the Dongpu Depression, China, as major caprocks of the Shahejie Formation. Previous studies have suggested that the decline of formation pressure during the Dongying movement is accompanied by petroleum leakage, but they lack any direct evidence of failed integrity of the salt caprocks. Therefore, fluid inclusion analysis under both incident ultraviolet (UV) and transmitted light (TR) modes on halite samples were conducted in this study, supported by basin and fluid inclusion PVTX modeling to prove lack of integrity in the caprock, periodically. Our observation showed that various types of hydrocarbon inclusions exist in halite crystals, revealing multi-stage fracturing and healing processes inside the salt caprocks. Coupling the PVTX and basin modeling results, revealed that oil inclusions were trapped at around 6.6 Ma during the secondary hydrocarbon generation of the source rocks. Moreover, salt caprocks failed due to the overpressure that was formed during hydrocarbon generation. This was exacerbated by the following uplifting which ultimately led to the present-day normal reservoir pressure in the sampled depth. In addition, the fluorescence of oil inclusions in the same fracture gradually changed from orange to blue. This proved that analyzing the thermal maturity of trapped hydrocarbons within the inclusions, solely based on the fluorescence color, could be misleading and other submicron scale analytical methods should be employed to examine the inclusions. Overall, this study enabled us to investigate the caprock integrity via optical methods, which can eventually help us to avoid regions where hydrocarbon is lost vs. prolific areas in the formation understudy.
Crossing conjugate normal faults (CCNFs) are extensively developed in many hydrocarbon-producing basins, generally existing in the form of incomplete CCNFs. Nevertheless, the effect of the non-conjugate zone of the CCNFs on the conjugate relay zone post late tectonic action has not been previously studied. We use 3D elastic-plastic modeling to investigate the influence of incomplete (i.e., partially intersecting) CCNFs on the pattern of deformation of strata in the intersection region. A series of model simulations were performed to examine the effects of horizontal tectonic extension, fault size, and fault depth on the deformation of conjugate relay zones of incomplete CCNFs. Our analyses yielded the following results. (1) The model of incomplete conjugation predicts a convex-up style of deformation in the conjugate graben region superimposed on overall subsidence under applied horizontal tectonic extension. (2) The degree of convex-up deformation of the conjugate graben depends on the influence of the non-conjugate zone on the conjugate relay zone, which varies with the amount of horizontal tectonic extension, fault size, and fault burial depth. (3) Our results indicate that incomplete CCNFs can form convex-up deformation, similar to that in the Nanpu Sag area and provide a sound understanding of hydrocarbon migration and accumulation.
Ultra‐deep marine carbonate reservoirs is an important field for oil and gas exploration, and it is also a hot research topic in recent years. However, their hydrocarbon episodic charging model is still under debate up to now. A great breakthrough has been made in the newly discovered ultra‐deep fault‐karst oil reservoir in the Shunbei area of Tarim Basin. Based on quantitative gas chromatogram‐mass spectrometry, stable carbon isotopes of reservoir oils, microthermometry and confocal laser scanning analyses of fluid inclusions, the reservoir oil origin and hydrocarbon charging history in Shunbei No. 1, No. 5 and No. 7 strike‐slip fault zones are expounded. The results showed that the Ordovician reservoir oil derives from the source rocks within the Cambrian Yuertusi Formation deposited in a highly anoxic bottom water environment. There were four stages of hydrocarbon charging in the study area, in the late Caledonian, late Hercynian–Indosinian, middle Yanshanian and late Himalayan. During this period, the force‐field strength of the charged oil gradually decreased, and the early‐stage charged crude oil with low maturity and high force‐field strength preferentially accumulated in the Yijianfang Formation, while the late‐stage charged crude oil with high maturity and low force‐field strength preferentially accumulated in the Yingshan Formation. This study reveals the history and differences of petroleum accumulation in the Shunbei fault zones, which is significance for understanding the hydrocarbon distribution in ultra‐deep marine carbonate reservoirs.
