Critical conditions for natural gas charging and delineation of effective gas source rocks for tight sandstone reservoirs

2014 ◽  
Vol 51 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Fujie Jiang ◽  
Xiongqi Pang ◽  
Fengtao Guo ◽  
Jigang Guo
Keyword(s):  
Natural Gas ◽  
Source Rocks ◽  
Critical Conditions ◽  
Tight Sandstone ◽  
Gas Source ◽  
Sandstone Reservoirs

scholarly journals Hydrocarbon geochemistry and charging history of the deep tight sandstone reservoirs in the Dabei Gas Field, Kuqa Depression, Tarim Basin, NW China

2020 ◽  
Vol 38 (6) ◽  
pp. 2325-2355
Author(s):  
Qiang Wei ◽  
Xianqing Li ◽  
Kexin Sun ◽  
Guangwu Zhang ◽  
Wanle Liang ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Natural Gas ◽  
Source Rocks ◽  
Tight Sandstone ◽  
Gas Field ◽  
Kuqa Depression ◽  
Natural Gases ◽  
History Of ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs

The geochemical feature and evolutionary history of hydrocarbons from the deep Cretaceous Bashijiqike (K1 bs) Formation tight sandstone reservoir in the Dabei Gas Field, Kuqa Depression were investigated using gas chromatography, gas chromatography–mass spectrometry, inclusions petrography and micro-thermometry, laser Raman spectroscopy, and quantitative grain fluorescence. The result indicates that natural gases from the deep sandstone reservoir are mainly composed of alkanes and belong to dry gases, of which methane accounts for 94.30–97.20% (avg. 95.64%), and ethane is 1.23–2.45% (avg. 1.95%). The stable carbon isotopic value of methane and ethane is −31.9‰ to −29.3‰ (avg. −30.3‰) and −24.2‰ to −19.4‰ (avg. −21.7‰), respectively, and this reflects the features of high-mature coal-derived gases. In addition, natural gases in the Dabei Gas Field have characteristics of coal-derived gases which were sourced from Jurassic coal measures. Oils in the Dabei Gas Field predominately originated from Triassic Huangshanjie (T3 h) Formation mudstones with some contributions from Jurassic coaly rocks. Petrological and micro-thermometry results of fluid inclusions suggest that the K1 bs Formation tight sandstone reservoirs have experienced two phases of hydrocarbons charge histories, namely “early oil and later gas.” The quantitative grain fluorescence analysis indicated that sandstone samples with quantitative grain fluorescence index value >5 and quantitative grain fluorescence-extraction intensity >40 pc in Wells DB101 and DB2 can be used as indicators for the paleo oil layers or the migration channels of later charged natural gas. The aforementioned analyses and burial and thermal histories of K1 bs sandstone reservoir demonstrated that oil charged at 10 Ma and natural gas charged at approximately 3 Ma in the study area. Furthermore, paleo-tectonic evolution enabled source rocks to mature and expel hydrocarbons, and the structurally related faults and traps provided pathways and places for hydrocarbon migration and accumulation.

scholarly journals Light hydrocarbon geochemical characteristics and their application in Upper Paleozoic, Shenmu gas field, Ordos Basin

2016 ◽  
Vol 35 (1) ◽  
pp. 103-121 ◽  
Author(s):  
Wenxue Han ◽  
Shizhen Tao ◽  
Guoyi Hu ◽  
Weijiao Ma ◽  
Dan Liu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Ordos Basin ◽  
Light Hydrocarbon ◽  
Source Rocks ◽  
Higher Plant ◽  
Gas Field ◽  
Gas Source ◽  
Upper Paleozoic ◽  
Methyl Cyclohexane ◽  
Normal Stage

Light hydrocarbon has abundant geochemical information, but there are few studies on it in Shenmu gas field. Taking Upper Paleozoic in Shenmu gas field as an example, authors use gas chromatography technology to study light hydrocarbon systematically. The results show that (1) The Shenmu gas field is mainly coal-derived gas, which is mixed by partial oil-derived gas due to the experiment data. (2) Based on K1, K2 parameter and Halpern star chart, the Upper Paleozoic gas in Shenmu gas field belongs to the same petroleum system and the depositional environment of natural gas source rocks should be homologous. (3) The source rocks are mainly from terrestrial higher plant origins and belong to swamp facies humic due to methyl cyclohexane index and Mango parameter intersection chart, which excluded the possibility of the Upper Paleozoic limestone as source rocks. (4) The isoheptane ranges from 1.45 to 2.69 with an average of 2.32, and n-heptane ranges from 9.48 to 17.68% with an average of 11.71%, which is below 20%. The maturity of Upper Paleozoic gas in Shenmu gas field is low-normal stage, which is consistent with Ro data. (5) The Upper Paleozoic natural gas in the Shenmu gas field did not experience prolonged migration or secondary changes, thus can be analyzed by light hydrocarbon index precisely.

scholarly journals Conventionally trapped natural gas accumulations in the Jurassic tight sandstone reservoirs: A case study from the Center of the Western Sichuan Basin, SW China

2017 ◽  
Vol 36 (5) ◽  
pp. 1022-1039 ◽  
Author(s):  
Yingchun Guo ◽  
Licai Song ◽  
Xinxin Fang ◽  
Kaixun Zhang
Keyword(s):  
Sichuan Basin ◽  
Low Permeability ◽  
Gas Migration ◽  
Tight Sandstone ◽  
Long Distance ◽  
Western Sichuan ◽  
Reservoir Rocks ◽  
Gas Source ◽  
Sandstone Reservoirs ◽  
Western Sichuan Basin

Tight gas accumulations, commonly characterized by low permeability, low porosity, and complicated pore structure, are widely distributed in the Sichuan Basin. Recent exploration in the Chengdu Sag, Western Sichuan Basin has proven that Jurassic tight-sandstone reservoirs attach significant gas potential. However, long distance migration between source and reservoir intervals entangles understanding of the tight-gas accumulation mechanism. It is unclear whether producible gas in Jurassic intervals is either from “simple sweet-spots in a continuous accumulation” or “conventionally trapped accumulations in low-permeability reservoir rocks”. To identify the regionally active gas system and characterize the charging pattern, a geochemical study was performed by interpreting the gas molecular and carbon isotope compositions in Jurassic and conducting gas–source correlations as well as gas migration distance calculation with the relationship among δ13C1 vs. Ro vs. H (burial depth). Research results indicate that the Jurassic tight gases in Majing-Shifang areas are coal-derived dry gases generated by the primary cracking of kerogen. Gas/source correlation and gas migration distance calculation reveal that gases are mainly sourced from the Upper Triassic humic source rocks (T3 x5, the fifth member of the Xujiahe Formation). Gas accumulations in the Jurassic Penglaizhen Formation were formed with an original vertical migration of about 2–3 km and then a long-distance lateral migration within tight sand layers, which is verified by the decreasing δ13C1 and the general increasing iC4/ nC4 in the Penglaizhen Formation. The Jurassic tight-sandstone reservoirs in Majing-Shifang areas occur in low-porosity and low-permeability reservoir rocks in conventional lithological traps, which are not continuous-type gas accumulations or basin-centered gas systems. The faults in Majing area serve as dominant vertical conducting pathway and the relatively permeable intervals within Jurassic and microfractures play an important role in the development of the conventionally trapped natural gas accumulations.

scholarly journals Significance and evolution characteristics of the isobutane/n-butane ratio of natural gas

2019 ◽  
Vol 38 (2) ◽  
pp. 494-518
Author(s):  
Nian Liu ◽  
Nansheng Qiu ◽  
Zhenming Li ◽  
Chuan Cai ◽  
Xinjie Shan ◽  
...  
Keyword(s):  
Natural Gas ◽  
Mathematical Models ◽  
Source Rock ◽  
Ordos Basin ◽  
The United States ◽  
Source Rocks ◽  
Initial Increase ◽  
Gas Field ◽  
Gas Source ◽  
Carbonium Ion

In previous studies, two conflicting conclusions existed, which were: (a) the isobutane/n-butane ratio of natural gas increases with the increasing maturity (Ro) of source rocks and (b) decreases with the increasing Ro. In this paper, the correlations between the isobutane/n-butane ratios, dryness of natural gases, and the Ro values of source rocks of 77 gas samples from Cretaceous and Tertiary in Kuqa Depression, Tarim Basin, Triassic Xujiahe Formation in central Sichuan Basin, Carboniferous–Permian in Sulige and Yulin gas field, Ordos Basin, China, and 80 shale gas samples from Mississippian Barnett Shale in the Fort Worth Basin, the United States are analyzed to reveal the evolution of the isobutane/n-butane ratios, then mathematical models of the isobutane/n-butane ratios and Ro are attempted to be established. Results show that the isobutane/n-butane ratio initially increases and then decreases with increasing Ro, both coal-derived gas and oil-type gas. Diverse types of kerogens may be responsible for the different corresponding Ro values when the isobutane/n-butane ratios of gases reach their maximum values. The initial increase in the isobutane/n-butane ratios with increasing Ro is the reason that isobutane is mainly generated at a higher rate by carbonium ion reaction of α-olefins with protons during kerogen primary cracking at lower maturity, whereas free radical reactions to form n-butane relatively quickly during oil cracking at higher maturity and isobutane cracked at a higher rate during the wet gas cracking stage may result in the terminal decreases in the isobutane/n-butane ratios. Besides, mathematical models of the isobutane/n-butane ratios of different types of natural gas and maturity are established. Therefore, the maturity of gas source rock can be obtained quickly based on the models using the isobutane/n-butane ratio combined with other component information (such as dryness, wetness, etc.), which is of great significance to the characterization of natural gas maturity and gas source rock correlation.

Fracture and Gas Potential in Tight Sandstone Reservoirs in the Eastern Part of Sulige Gas Field, Ordos Basin (China)

2012 ◽  
Vol 524-527 ◽  
pp. 1236-1240
Author(s):  
Ren Chao Yang ◽  
Yi Jun Li ◽  
Tao Zhang ◽  
Ai Ping Fan ◽  
Yan Long Wang
Keyword(s):  
Natural Gas ◽  
Ordos Basin ◽  
Sem Analysis ◽  
Tight Sandstone ◽  
Gas Field ◽  
High Productivity ◽  
Distribution Laws ◽  
Sandstone Reservoirs ◽  
Gas Potential ◽  
Better Than

Sulige gas field in Ordos Basin is the largest discovered gas field in China. But tight sandstone reservoirs is becoming the main limitation of natural gas exploration and exploitation in Sulige gas field. Intensively analysis on micro-pore structure of sandstone reservoirs in Shan1 member of Shanxi formation and He8 member of Shihexizi formation in Permian system in the eastern part of Sulige gas field are conducted by means of drill core observation, slice identification, SEM analysis, casting slice and mercury injection etc. analytical methods. Result shows that fracture is well developed in sandstone reservoirs in the northern part of the interest area, by which petrophysical property of tight sandstone reservoir is improved distinctly. Types of fracture are dominated by diaclase and the diagenesis cracks. Main direction of the fractures is NE and NW, and the angle of the two groups fractures is nearly 90°.But one set of the conjugate shear fractures would develop well and the other was rest rained by the influenced of strong anisotropism of sandbodies. Diaclase and the diagenesis cracks developed along the boundery of tectonic divisions. Fracture is one of the important reasons for improvement of permeability in tight sandstone reservoirs. Gas potential of sandstone in fracture-developed section is much better than that of non-fracture section. Consequently, it is signaficant for all of reservoir forecasting, high productivity gas pool seeking, design and construction of natural gas exploitation to grasp distribution laws of fracture.

scholarly journals The Evolution of Diagenetic Fluids and Accumulation Characteristics of Tight Sandstone Reservoir in Upper Paleozoic, Southwestern Ordos Basin

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Ruijing Zhu ◽  
Rongxi Li ◽  
Xiaoli Wu ◽  
Xiaoli Qin ◽  
Bangsheng Zhao ◽  
...  
Keyword(s):  
Natural Gas ◽  
Clay Minerals ◽  
Ordos Basin ◽  
Source Rocks ◽  
Fluid Inclusion Study ◽  
Hydrocarbon Accumulation ◽  
Tight Sandstone ◽  
Upper Paleozoic ◽  
Two Stages ◽  
Accumulation Characteristics

The Upper Paleozoic in the southwestern Ordos Basin has significant potential for natural gas exploration. This study investigated the diagenetic fluid evolution and hydrocarbon accumulation characteristics of He 8 section from Permian Lower Shihezi formation and Shan 1 section from Shanxi formation tight sandstone reservoirs by petrographic observation, scanning electron microscope imaging, fluid inclusion study, and laser Raman spectrum analysis. The results show that He 8 section and Shan 1 section reservoirs are mainly composed of quartz sandstone, subordinate arkose quartz sandstone, and lithic quartz sandstone, with minor lithic sandstone and lithic arkose sandstone. The major pores are intergranular dissolved pores. The main diagenetic minerals include quartz overgrowth, siliceous cement, carbonate cement, illite, montmorillonite, and mixed-layer clay minerals. The overall diagenetic features show strong compaction, multistage siliceous and calcareous cements, and abundant clay minerals, strong dissolution, and well-developed fractures. Two stages of fluid inclusions developed in the He 8 and Shan 1 sections recorded the migration and accumulation of the early-stage and late-stage natural gas, respectively. The reservoir in the study area experienced early and late diagenetic stages, and its formation was simultaneous with or after its densification. The diagenetic environment changed from alkaline to acidic and again into alkaline. There are two stages of fluid activities in the study area, namely, the early diagenetic stage corresponding to hydrocarbon generation and migration and the late diagenetic stage corresponding to hydrocarbon accumulation. This study suggests that Upper Paleozoic natural gas migrated into the reservoir in Weibei Uplift, Yishan Slope, and Tianhuan Depression tectonic units during 220-197 Ma, and the large-scale migration and accumulation occurred in these tectonic units at different times. No natural gas was generated in the west margin of the basin because the temperatures of the hydrocarbon source rocks in the Upper Paleozoic were below the gas window.

THE PROBLEMS OF DETERMINING THE CONTENT OF KEROGEN IN THE OIL AND GAS SOURCE ROCKS

2019 ◽  
pp. 69-74
Author(s):  
N.I. Samokhvalov ◽  
◽  
K.V. Kovalenko ◽  
N.A. Skibitskaya ◽  
◽  
...  
Keyword(s):  
Oil And Gas ◽  
Source Rocks ◽  
Gas Source
Sign in / Sign up

Export Citation Format

Share Document