scholarly journals Differential hydrocarbon enrichment in deep Paleogene tight sandstones of the Dongpu Depression in Eastern China

2021 ◽  
pp. 014459872098811
Author(s):  
Yuanyuan Zhang ◽  
Zhanli Ren ◽  
Youlu Jiang ◽  
Jingdong Liu

To clarify the characteristics and enrichment rules of Paleogene tight sandstone reservoirs inside the rifted-basin of Eastern China, the third member of Shahejie Formation (abbreviated as Es3) in Wendong area of Dongpu Depression is selected as the research object. It not only clarified the geochemical characteristics of oil and natural gas in the Es3 of Wendong area through testing and analysis of crude oil biomarkers, natural gas components and carbon isotopes, etc.; but also compared and explained the types and geneses of oil and gas reservoirs in slope zone and sub-sag zone by matching relationship between the porosity evolution of tight reservoirs and the charging process of hydrocarbons. Significant differences have been found between the properties and the enrichment rules of hydrocarbon reservoirs in different structural areas in Wendong area. The study shows that the Paleogene hydrocarbon resources are quasi-continuous distribution in Wendong area. The late kerogen pyrolysis gas, light crude oil, medium crude oil, oil-cracked gas and the early kerogen pyrolysis gas are distributed in a semicircle successively, from the center of sub-sag zone to the uplift belt, that is the result of two discontinuous hydrocarbon charging. Among them, the slope zone is dominated by early conventional filling of oil-gas mixture (at the late deposition period of Dongying Formation, about 31–27 Ma ago), while the reservoirs are gradually densified in the late stage without large-scale hydrocarbon charging (since the deposition stage of Minghuazhen Formation, about 6–0 Ma). In contrast, the sub-sag zone is lack of oil reservoirs, but a lot of late kerogen pyrolysis gas reservoirs are enriched, and the reservoir densification and hydrocarbon filling occur in both early and late stages.

2015 ◽  
Vol 52 (10) ◽  
pp. 880-892 ◽  
Author(s):  
Junqing Chen ◽  
Xiongqi Pang ◽  
Zhenxue Jiang

Seven hydrocarbon reservoirs have been discovered to date in the Upper Ordovician of the Tazhong Area, a region in which hydrocarbon phase distribution is complex. In the present study, the genesis and controlling factors of the hydrocarbons with complex phase in the Tazhong Area were investigated on the basis of the geological and geochemical conditions required for the formation and distribution of hydrocarbon reservoirs, integrated with the source rock geochemistry, natural gas and oil properties, and oil and gas reservoir fluid tests PVT (i.e., pressure, volume, and temperature tests). The results indicate that hydrocarbon reservoir types in the Upper Ordovician of the Tazhong Area transition from unsaturated to saturated condensate-gas reservoirs from west to east and from condensate-gas reservoirs to unsaturated-oil reservoirs from north to south. The crude oil in the region originated primarily from the mixing of Lower–Middle Cambrian and Middle–Upper Ordovician source rocks, while the natural gas was sourced primarily from the cracking gas of Lower–Middle Cambrian crude oil. This hydrocarbon-phase distribution was controlled primarily by temperature and pressure and has been affected by multiple periods of hydrocarbon accumulation and alteration. The high-quality Lower–Middle Cambrian reservoir–cap assemblage may be an important target for future exploration of natural gas in the Tazhong Area.


Rare gases are conservative tracers of subsurface fluid movement. The mass balance of atmosphere-derived and crustally produced radiogenic and nucleogenic rare gases in natural gas reservoirs allows straightforward constraints to be placed on scales of fluid movement in sedimentary basins. The details of large-scale fluid movements in Neogene sedimentary basins appear to differ according to their thermal structures.


2011 ◽  
Vol 347-353 ◽  
pp. 1561-1567 ◽  
Author(s):  
Shu Jun Huang ◽  
Hui Zhang ◽  
Cui Juan Shang ◽  
Shu Long Jing

In this paper, according to research difficulties of rebuilding underground natural gas storages from carbonate buried hill gas reservoirs, we select a variety of relevant technologies and methods to study. Considering the reservoir geologic features geology, the impact of water intrusion, the difference of reserve calculations and many other factors, we carry out the research and determine the key parameters of rebuilding underground natural gas storages, and finally get a reasonable understanding of the study. Upon completion of large-scale gas storage for research results, further to form the distinctive key technologies of rebuilding underground natural gas storages from carbonate buried hill gas reservoirs. The research results will provide the appropriate technical reference for similar future rebuilding underground gas storages and also provide the technical assurance for a safe and stable gas supply to Beijing, Tianjin and Hebei region.


2021 ◽  
Vol 248 ◽  
pp. 01071
Author(s):  
Tingwei Yao ◽  
Yang Zhang ◽  
Minhao Guo ◽  
Zhilin Tuo ◽  
Haiyang Wang ◽  
...  

In the process of continuous production of natural gas wells, formation pressure and gas flow rate decrease continuously. The ability to carry liquid decreases continuously, thus gradually forming bottom hole liquid. Bottom hole liquid accumulation is an important reason for the decrease of production or shutdown of natural gas wells. How to diagnose whether there is liquid accumulation in natural gas wells and identify the degree of liquid accumulation, to adopt drainage gas recovery operation in time, is the research focus of efficient development of natural gas reservoirs. In this paper, a method for diagnosing bottom hole liquid accumulation combining production performance curve and modified Fernando inclined well critical liquid-carrying model is designed for a large scale double-branch horizontal well used in unconventional reservoirs. The method is applied to the Well X2 of He 8 Member in PCOC. The application results showed that there was no liquid accumulation in the horizontal and vertical sections of the Well X2. The liquid in the wellbore was generated at the bottom of the inclined section and the liquid accumulation is upward along the wellbore from the bottom of the inclined section, with the height of 3 m.


2020 ◽  
Vol 16 (9) ◽  
pp. 1656-1673
Author(s):  
V.V. Smirnov

Subject. The article discusses financial and economic momenta. Objectives. I determine financial and economic momenta as the interest rate changes in Russia. Methods. The study is based on a systems approach and the method of statistical analysis. Results. The Russian economy was found to strongly depend on prices for crude oil and natural gas, thus throwing Russia to the outskirts of the global capitalism, though keeping the status of an energy superpower, which ensures a sustainable growth in the global economy by increasing the external consumption and decreasing the domestic one. The devaluation of the national currency, a drop in tax revenue, etc. result from the decreased interest rate. They all require to increase M2 and the devalued retail loan in RUB, thus rising the GDP deflator. As for positive effects, the Central Bank operates sustainably, replenishes gold reserves and keeps the trade balance (positive balance), thus strengthening its resilience during a global drop in crude oil prices and the COVID-19 pandemic. The positive effects were discovered to result from a decreased in the interest rate, rather than keeping it low all the time. Conclusions and Relevance. As the interest rate may be, the financial and economic momentum in Russia depends on the volatility of the price for crude oil and natural gas. Lowering the interest rate and devaluing the national currency, the Central Bank preserves the resource structure of the Russian economy, strengthens its positions within the global capitalism and keeps its status of an energy superpower, thus reinforcing its resilience against a global drop in oil prices.


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