Using well-log data to modeling factors influencing the amount of adsorbed gas in transitional shale reservoirs

2020 ◽  
Vol 8 (2) ◽  
pp. T249-T258
Author(s):  
Rui Liu ◽  
Shaobin Guo ◽  
Kun Ji
Keyword(s):  
Adsorption Capacity ◽  
Mineral Composition ◽  
Ordos Basin ◽  
Well Log ◽  
Isothermal Adsorption ◽  
Adsorbed Gas ◽  
Upper Paleozoic ◽  
Rapid Changes ◽  
Shale Reservoirs ◽  
Experimental Values

Traditional isothermal adsorption experiments often fail to accurately estimate the adsorption capacity of reservoirs with rapidly changing lithology. Temperature, pressure, and mineral composition can influence the adsorption capacity of shale reservoirs. We have examined the influence of these factors on the amount of gas adsorbed in samples from well Yu-88. Samples consist of marine-continental transitional coal-bearing strata from the Upper Paleozoic Shanxi-Taiyuan Formation of the Ordos Basin of China. Shales occur as frequently interbedded, thin, and single layers that exhibit large cumulative thickness and rapid changes in mineral composition. Our experiments on samples B1 and B2 indicated that Langmuir constant [Formula: see text] varied inversely with temperature, but Langmuir pressure [Formula: see text] did not. The [Formula: see text] exhibits good correlation with illite as well as illite/smectite content but did not clearly correlate with the total organic carbon (TOC). The [Formula: see text] correlated positively with TOC and negatively with illite/smectite content. These relationships enabled modeling of [Formula: see text], [Formula: see text], and mineral composition. Novel step-by-step modeling methods of well logs generated optimized estimates for well-log parameters including mineral composition. According to the actual temperature of the reservoir, we corrected the Langmuir constant [Formula: see text]. We calculated a profile for the amount of gas adsorbed in shale intervals of well Yu-88. Comparisons with experimental values indicate relatively high reference values.

scholarly journals Adsorption Characteristics and Controlling Factors of CH4 on Coal-Measure Shale, Hedong Coalfield

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Weidong Xie ◽  
Meng Wang ◽  
Hongyue Duan
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Mineral Composition ◽  
Shale Gas ◽  
Total Content ◽  
Coal Measure ◽  
Gas Reservoirs ◽  
Quartz Content ◽  
Adsorption Characteristics ◽  
Adsorbed Gas

Adsorbed gas is one of the crucial occurrences in shale gas reservoirs; thus, it is of great significance to ascertain the adsorption capacity of shale and the adsorption characteristics of CH4. In this investigation, the Taiyuan–Shanxi Formations’ coal-measure shale gas reservoir of the Carboniferous–Permian era in the Hedong Coalfield was treated as the research target. Our results exhibit that the shale samples were characterized by a high total organic carbon (TOC) and over to high-over maturity, with an average TOC of 2.45% and average Ro of 2.59%. The mineral composition was dominated by clay (62% on average) and quartz (22.45% on average), and clay was mainly composed of kaolinite and illite. The Langmuir model showed a perfect fitting degree to the experimental data: VL was in the range of 0.01 cm3/g to 0.77 cm3/g and PL was in the range of 0.23–8.58 MPa. In addition, the fitting degree depicted a linear negative correlation versus TOC, while mineral composition did not exhibit a significant effect on the fitting degree, which was caused by the complex pore structure of organic matter, and the applicability of the monolayer adsorption theory was lower than that of CH4 adsorption on the mineral’s pore surface. An apparent linear positive correlation of VL versus the TOC value was recorded; furthermore, the normalized VL increased with the growth of the total content of clay mineral (TCCM), decreased with the growth of the total content of brittle mineral (TCBM), while there was no obvious correlation of normalized VL versus kaolinite, illite and quartz content. The huge amount of micropores and complex internal structure led to organic matter possessing a strong adsorption capacity for CH4, and clay minerals also promoted adsorption due to the development of interlayer pores and intergranular pores.

scholarly journals Geological models and controlling factors of gas content in marine–terrigenous shale in the Southern Qinshui Basin, China

2018 ◽  
Vol 37 (1) ◽  
pp. 375-393 ◽  
Author(s):  
Xiaowei Hou ◽  
Yanming Zhu ◽  
Zhenfei Jiang ◽  
Haitao Gao
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Carbon Content ◽  
Adsorption Capacity ◽  
Total Organic Carbon Content ◽  
Gas Content ◽  
Organic Carbon Content ◽  
Isothermal Adsorption ◽  
Free Gas ◽  
Adsorbed Gas

Geological prediction models for gas content in marine–terrigenous shale under the effects of reservoir characteristics and in situ geological conditions, were established using methane isothermal adsorption, high temperature/pressure methane isothermal adsorption, total organic carbon, X-ray diffraction, mercury porosimetry, porosity in net confining stress, and field desorption methods. Results indicated that the adsorption capacity of marine–terrigenous shale has a linearly positive correlation with total organic carbon content and maturity. Clay and quartz minerals are the two main components of inorganic minerals in marine–terrigenous shale, with an average content of 54.3% and 36.9%, respectively. Adsorption capacity of marine–terrigenous shale is slightly positive correlated with clay content, while it exponentially decreases with increasing quartz content. The effects of in situ temperature and reservoir pressure on adsorption capacity in marine–terrigenous shale are also significant. The adsorption capacity of marine–terrigenous shale shows a clear decreasing trend as temperature increases, while it increases with increasing reservoir pressure. The porosity of marine–terrigenous shale is characterized by highly stress-sensitive, decreasing exponentially with increasing effective stress, which results in a more complex occurrence of free gas in deep shale reservoirs. In addition, gas saturation for the shale samples was calculated based on the results of field desorption, after which geological prediction models of total gas, adsorbed gas, and free gas were established while considering the coupled effects. Adsorbed gas, free gas, and total gas content all initially increase as burial depth increases, and then eventually decrease. Adsorbed gas content and free gas content have a positive correlation with total organic carbon content and porosity, indicating that the total gas content at different burial depths is mainly controlled by the total organic carbon content and porosity.

Effect of Thermal Maturity on Pore Type and Size in Transitional Shale Reservoirs: An Example from the Upper Paleozoic Shanxi Formation, Ordos Basin, China

2020 ◽  
Vol 34 (12) ◽  
pp. 15736-15751
Author(s):  
Chunqi Xue ◽  
Jianguang Wu ◽  
Longwei Qiu ◽  
QuYang Liu ◽  
Jianhua Zhong
Keyword(s):  
Ordos Basin ◽  
Thermal Maturity ◽  
Upper Paleozoic ◽  
Shale Reservoirs

Nanoscale Pore Structure Characteristics of Deep Coalbed Methane Reservoirs and Its Influence on CH4 Adsorption in the Linxing Area, Eastern Ordos Basin, China

2021 ◽  
Vol 21 (1) ◽  
pp. 43-56
Author(s):  
Xiang-Dong Gao ◽  
Yan-Bin Wang ◽  
Xiang Wu ◽  
Yong Li ◽  
Xiao-Ming Ni ◽  
...  
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Coalbed Methane ◽  
Ordos Basin ◽  
Rapid Decline ◽  
Burial Depth ◽  
Coal Rank ◽  
Coal Seams ◽  
Isothermal Adsorption ◽  
Nanoscale Pore

The high gas content of deep coal seams is a driving force for the exploration and development of deep coalbed methane (CBM). The nanoscale pores, which are the main spaces for adsorption and storage of CBM, are closely related to the burial depth. Based on integrated approaches of vitrinite reflectance (Ro), maceral composition, scanning electron microscope (SEM), proximate analysis, fluid inclusion test, low-temperature N2 adsorption–desorption, and CH4 isothermal adsorption, the nanoscale pore structure of coals recovered at depths from 650 to 2078 m was determined, and its influence on the CH4 adsorption capacity was discussed. The results show that the coal rank has a good linear relationship with the current burial depth of the coal seams; that is, the influences of the burial depth on the coals can be reflected by the influences of the coal rank on the coals. With the increase in the coal rank, the moisture and volatile content decrease, and the fixed carbon content increases. The variation in the pore volume and specific surface area with the increase in the coal rank can be divided into two stages: the rapid decline stage (when 0.75%<Ro < 1.0%), dominated by the compaction and gelatinization, and the slow decline stage (when 1.0%<Ro < 1.35%), characterized by the low stress sensitivity and the mass production of secondary pores. The percentage of micropores increases throughout the process. When 10 nm is taken as the boundary, the nanoscale pores show different fractal features. When Ro < 1.0%, the fractal dimension (FD) of the micropores is close to 3. When Ro > 1.0%, the FD of the micropores is close to 2. This indicates that with the increase in the degree of coalification, the surface of the micropores is simpler. The above results show that the gas adsorption capacity of coal first slightly decreases (when 0.75% < Ro < 1.0%) and then increases (when 1.0% < Ro < 1.35%), and the coincident results are shown in the Langmuir volume (VL) test results.

MORE ACCURATE QUANTIFICATION OF FREE AND ADSORBED GAS IN SHALE RESERVOIRS

2019 ◽  
Vol 60 (5) ◽  
pp. 560-584
Author(s):  
Rafay Ansari ◽  
◽  
German Merletti ◽  
Pavel Gramin ◽  
Peter Armitage ◽  
...  
Keyword(s):  
Adsorbed Gas ◽  
Shale Reservoirs ◽  
Accurate Quantification

MORE ACCURATE QUANTIFICATION OF FREE AND ADSORBED GAS IN SHALE RESERVOIRS

2019 ◽  
Author(s):  
Rafay Ansari ◽  
German Merletti ◽  
Pavel Gramin ◽  
Peter Armitage
Keyword(s):  
Adsorbed Gas ◽  
Shale Reservoirs ◽  
Accurate Quantification

CHARACTERISTICS OF RESERVOIRS IN THE UPPER PALEOZOIC TIGHT SANDSTONE, LINXING BLOCK, ORDOS BASIN

2017 ◽  
Author(s):  
Chuang Liu ◽  
◽  
Jianguang Wu ◽  
Jianhua Zhong ◽  
Shouren Zhang ◽  
...  
Keyword(s):  
Ordos Basin ◽  
Tight Sandstone ◽  
Upper Paleozoic

scholarly journals Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

2021 ◽  
Author(s):  
Shangbin Chen ◽  
Chu Zhang ◽  
Xueyuan Li ◽  
Yingkun Zhang ◽  
Xiaoqi Wang
Keyword(s):  
Organic Matter ◽  
Pore Size ◽  
Adsorption Capacity ◽  
Thermal Evolution ◽  
Methane Adsorption ◽  
Storage Site ◽  
Pressure Sensitivity ◽  
Adsorption Characteristics ◽  
Shale Reservoirs ◽  
Organic Pores

AbstractIn shale reservoirs, the organic pores with various structures formed during the thermal evolution of organic matter are the main storage site for adsorbed methane. However, in the process of thermal evolution, the adsorption characteristics of methane in multi type and multi-scale organic matter pores have not been sufficiently studied. In this study, the molecular simulation method was used to study the adsorption characteristics of methane based on the geological conditions of Longmaxi Formation shale reservoir in Sichuan Basin, China. The results show that the characteristics of pore structure will affect the methane adsorption characteristics. The adsorption capacity of slit-pores for methane is much higher than that of cylindrical pores. The groove space inside the pore will change the density distribution of methane molecules in the pore, greatly improve the adsorption capacity of the pore, and increase the pressure sensitivity of the adsorption process. Although the variation of methane adsorption characteristics of different shapes is not consistent with pore size, all pores have the strongest methane adsorption capacity when the pore size is about 2 nm. In addition, the changes of temperature and pressure during the thermal evolution are also important factors to control the methane adsorption characteristics. The pore adsorption capacity first increases and then decreases with the increase of pressure, and increases with the increase of temperature. In the early stage of thermal evolution, pore adsorption capacity is strong and pressure sensitivity is weak; while in the late stage, it is on the contrary.

scholarly journals Formation mechanism of authigenic chlorite in tight sandstone and its influence on tight oil adsorption, Triassic Ordos Basin, China

2020 ◽  
Vol 38 (6) ◽  
pp. 2667-2694
Author(s):  
Qianshan Zhou ◽  
Chengfu Lv ◽  
Chao Li ◽  
Guojun Chen ◽  
Xiaofeng Ma ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Formation Mechanism ◽  
Pore Space ◽  
Ordos Basin ◽  
Reservoir Quality ◽  
Tight Oil ◽  
Pressurized Water ◽  
Tight Reservoirs ◽  
Pore Lining ◽  
Scanning Electron

In this study, the formation mechanism of authigenic chlorite in tight reservoirs and its influence on the adsorption capacity to tight oil have been analyzed. The occurrence states of chlorite and the formation mechanism have been analyzed by thin section (TS) and field emission scanning electron microscopy (FE-SEM) measurements. Due to the alteration of volcanic rock fragments, the mudstone pressurized water, and the dissolution of early chlorite, the material source has been provided for the formation of chlorite. The formation time of chlorite with different occurrence states is in the following order: grain-coating chlorite → pore-lining chlorite → pore-lining chlorite in dissolved pores → rosette chlorite. Authigenic chlorite developed in the reservoirs has influenced the change of the reservoir quality in two respects. On the one hand, authigenic chlorite can protect the residual pores, improve the anti-compaction capacity of the reservoir, and provide certain inter-crystalline space. On the other hand, it can hinder pore space and inhibit throat, resulting in a decrease in the connectivity of pores and the increase in the heterogeneity of the reservoir. Tight oil absorbed by the chlorite is mainly in the form of the thin film and aggregates. Through in situ testing of environmental scanning electron microscope (ESEM) and energy dispersive spectrum (EDS), the adsorption capacity of chlorite with different occurrence states to tight oil, being in the following order: rosette chlorite > pore-lining chlorite > pore-lining chlorite in dissolved pores > grain-coating chlorite. Furthermore, the controlling factors on reservoir quality, the content of chlorite and content of Fe and K have been investigated, and the adsorption capacity of different chlorite types has been studied, which can provide guidance for analysis of the control factors on the difference in adsorption capacity of different occurrence states of chlorite to tight oil in tight reservoirs.

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