Geochemical characteristics of shale gas and its response to thermal maturity (Ro) in the Longmaxi formation, Dingshan area, Southeast Sichuan

2019 ◽  
Vol 37 (11) ◽  
pp. 1270-1278 ◽  
Author(s):  
Cheng Zhong ◽  
Qirong Qin ◽  
Cunhui Fan ◽  
Dongfeng Hu
Keyword(s):  
Shale Gas ◽  
Geochemical Characteristics ◽  
Thermal Maturity ◽  
Longmaxi Formation

scholarly journals Compositional and Isotopic Characteristics for The Longmaxi Shale Gas in The Northern Guizhou Area, South China

2020 ◽  
Author(s):  
Wenting Jiang ◽  
Peng Xia ◽  
Qingguang Li ◽  
Yong Fu ◽  
Yuliang Mou
Keyword(s):  
Shale Gas ◽  
Thermal Maturity ◽  
Hydrocarbon Gases ◽  
Longmaxi Formation ◽  
Isotope Distribution ◽  
Lower Silurian ◽  
Longmaxi Shale ◽  
Evolution Stage ◽  
Gaseous Hydrocarbons ◽  
Tectonic Movements

Abstract The organic-rich marine shale of the Lower Silurian Longmaxi formation in the northern Guizhou area (NGA), China, is characterized by its high thermal maturity (Ro values range in 2.18%~3.12%), high TOC values (0.92%~4.87%), high gas contents (0.47~2.69 m3/t) and type II1 organic matter, and has recently been a precursor for shale gas exploration and development. Compositional and isotopic parameters of 7 gas samples from Longmaxi shale from DY-1 well were analyzed in this study. Dry coefficient of the gases is up to 30~200 making the northern Guizhou Longmaxi shale gas among the driest gaseous hydrocarbons in the world. The δ13CCH4 values range from -38.6‰ to -18.6‰ and the δ13CC2H6 values vary in -36.2‰~-30.8‰. These results indicate that the Longmaxi shale gas is of thermogenic origin and oil derived. This Longmaxi shale gas has high proportion of non-hydrocarbon gases especially including nitrogen in response to complicate tectonic movements and strong hydrodynamic flushing. Tectonic movement and hydrodynamic flushing not only destroy hydrocarbon gases reservoirs but also change the isotope distribution of gaseous hydrocarbons. Isotopic reversal is frequent in closed system, and under relatively bad preserving condition, the isotope distribution will back to normal even at overmature evolution stage.

scholarly journals Geochemical characteristics and genetic mechanism of the high-N2 shale gas reservoir in the Longmaxi Formation, Dianqianbei Area, China

2020 ◽  
Vol 17 (4) ◽  
pp. 939-953
Author(s):  
Ji-Lin Li ◽  
Ting-Shan Zhang ◽  
Yan-Jun Li ◽  
Xing Liang ◽  
Xin Wang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Geochemical Characteristics ◽  
Genetic Mechanism ◽  
Gas Reservoir ◽  
Longmaxi Formation ◽  
Shale Gas Reservoir

Geochemical characteristics of Longmaxi Formation shale gas in the Weiyuan area, Sichuan Basin, China

2018 ◽  
Vol 167 ◽  
pp. 538-548 ◽  
Author(s):  
Ziqi Feng ◽  
Dazhong Dong ◽  
Jinqiang Tian ◽  
Zhen Qiu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Shale Gas ◽  
Sichuan Basin ◽  
Geochemical Characteristics ◽  
Longmaxi Formation

scholarly journals Coupling between Source Rock and Reservoir of Shale Gas in Wufeng-Longmaxi Formation in Sichuan Basin, South China

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2679
Author(s):  
Yuying Zhang ◽  
Shu Jiang ◽  
Zhiliang He ◽  
Yuchao Li ◽  
Dianshi Xiao ◽  
...  
Keyword(s):  
Source Rock ◽  
Shale Gas ◽  
Sichuan Basin ◽  
Gas Content ◽  
Potential Zone ◽  
Hydrocarbon Generation ◽  
Gas Generation ◽  
Longmaxi Formation ◽  
Siliceous Shale ◽  
Organic Pores

In order to analyze the main factors controlling shale gas accumulation and to predict the potential zone for shale gas exploration, the heterogeneous characteristics of the source rock and reservoir of the Wufeng-Longmaxi Formation in Sichuan Basin were discussed in detail, based on the data of petrology, sedimentology, reservoir physical properties and gas content. On this basis, the effect of coupling between source rock and reservoir on shale gas generation and reservation has been analyzed. The Wufeng-Longmaxi Formation black shale in the Sichuan Basin has been divided into 5 types of lithofacies, i.e., carbonaceous siliceous shale, carbonaceous argillaceous shale, composite shale, silty shale, and argillaceous shale, and 4 types of sedimentary microfacies, i.e., carbonaceous siliceous deep shelf, carbonaceous argillaceous deep shelf, silty argillaceous shallow shelf, and argillaceous shallow shelf. The total organic carbon (TOC) content ranged from 0.5% to 6.0% (mean 2.54%), which gradually decreased vertically from the bottom to the top and was controlled by the oxygen content of the bottom water. Most of the organic matter was sapropel in a high-over thermal maturity. The shale reservoir of Wufeng-Longmaxi Formation was characterized by low porosity and low permeability. Pore types were mainly <10 nm organic pores, especially in the lower member of the Longmaxi Formation. The size of organic pores increased sharply in the upper member of the Longmaxi Formation. The volumes of methane adsorption were between 1.431 m3/t and 3.719 m3/t, and the total gas contents were between 0.44 m3/t and 5.19 m3/t, both of which gradually decreased from the bottom upwards. Shale with a high TOC content in the carbonaceous siliceous/argillaceous deep shelf is considered to have significant potential for hydrocarbon generation and storage capacity for gas preservation, providing favorable conditions of the source rock and reservoir for shale gas.

scholarly journals Prediction of Shale Gas Reservoirs Using Fluid Mobility Attribute Driven by Post-Stack Seismic Data: A Case Study from Southern China

2020 ◽  
Vol 11 (1) ◽  
pp. 219
Author(s):  
Jing Zeng ◽  
Alexey Stovas ◽  
Handong Huang ◽  
Lixia Ren ◽  
Tianlei Tang
Keyword(s):  
Shale Gas ◽  
Seismic Data ◽  
Spectral Decomposition ◽  
Southern China ◽  
Gas Reservoirs ◽  
Seismic Attribute ◽  
Longmaxi Formation ◽  
Shale Gas Reservoirs ◽  
The Sichuan Basin ◽  
Shale Reservoirs

Paleozoic marine shale gas resources in Southern China present broad prospects for exploration and development. However, previous research has mostly focused on the shale in the Sichuan Basin. The research target of this study is expanded to the Lower Silurian Longmaxi shale outside the Sichuan Basin. A prediction scheme of shale gas reservoirs through the frequency-dependent seismic attribute technology is developed to reduce drilling risks of shale gas related to complex geological structure and low exploration level. Extracting frequency-dependent seismic attribute is inseparable from spectral decomposition technology, whereby the matching pursuit algorithm is commonly used. However, frequency interference in MP results in an erroneous time-frequency (TF) spectrum and affects the accuracy of seismic attribute. Firstly, a novel spectral decomposition technology is proposed to minimize the effect of frequency interference by integrating the MP and the ensemble empirical mode decomposition (EEMD). Synthetic and real data tests indicate that the proposed spectral decomposition technology provides a TF spectrum with higher accuracy and resolution than traditional MP. Then, a seismic fluid mobility attribute, extracted from the post-stack seismic data through the proposed spectral decomposition technology, is applied to characterize the shale reservoirs. The application result indicates that the seismic fluid mobility attribute can describe the spatial distribution of shale gas reservoirs well without well control. Based on the seismic fluid mobility attribute section, we have learned that the shale gas enrich areas are located near the bottom of the Longmaxi Formation. The inverted velocity data are also introduced to further verify the reliability of seismic fluid mobility. Finally, the thickness map of gas-bearing shale reservoirs in the Longmaxi Formation is obtained by combining the seismic fluid mobility attribute with the inverted velocity data, and two favorable exploration areas are suggested by analyzing the thickness, structure, and burial depth. The present work can not only be used to evaluate shale gas resources in the early stage of exploration, but also help to design the landing point and trajectory of directional drilling in the development stage.

Sign in / Sign up

Export Citation Format

Share Document