Prospect Analysis of Shale Gas Resource Exploration in the Lower Silurian Longmaxi Formation, Southeastern Margin of the Sichuan Basin, China

2014 ◽  
Vol 1014 ◽  
pp. 228-232 ◽  
Author(s):  
Chen Lin Hu ◽  
Yuan Fu Zhang ◽  
Zhi Feng Wang ◽  
Hai Bo Zhang
Keyword(s):  
Shale Gas ◽  
Sedimentary Environment ◽  
Source Rocks ◽  
Guizhou Province ◽  
Mature Stage ◽  
Carbonaceous Shale ◽  
Thin Sections ◽  
Longmaxi Formation ◽  
Lower Silurian ◽  
Longmaxi Shale

In order to understand the sedimentary characteristics of shale and prospects of shale gas exploration in the lower Silurian Longmaxi Formation northern of Guizhou Province, outcrop and core observations, thin sections, X-ray diffraction analysis and other means are used. Studies show that the thickness of Longmaxi formation shale is generally large, range from 20m to 200m, mainly develop in the water shelf. The mineral mainly compose of detrital quartz and clay minerals, and five lithofacies can be identified: black shale, silty shale, carbonaceous shale, calcareous shale and argillaceous siltstone. Longmaxi shale kerogen type is mainlyIand II, and Ro value is average of 1.87%, mainly in the mature - over mature stage. In addition, the TOC content and gas content of Longmaxi shale is high, what’s more, these two parameters have good positive correlation. Compared with the Barnett shale, both of them have some similarities in the development environment shale, shale thickness and type of organic matter and TOC content, while, Longmaxi shale is deeply buried and post-destruction more intense. Longmaxi shale sedimentary environment is stable, high shale thickness and stable distribution, good quality source rocks and high brittle mineral content, which has meet the basic parameters of shale gas exploration and development, and has a large shale gas exploration potential in study area.

Lithology and sedimentary heterogeneity of the Longmaxi Shale in the southern Sichuan Basin, China

2021 ◽  
pp. 1-49
Author(s):  
Boling Pu ◽  
Dazhong Dong ◽  
Ning Xin-jun ◽  
Shufang Wang ◽  
Yuman Wang ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Deep Water ◽  
Shale Gas ◽  
Sichuan Basin ◽  
Sedimentary Environment ◽  
Gas Production ◽  
Carbonaceous Shale ◽  
Gas Wells ◽  
Longmaxi Shale ◽  
Siliceous Shale

Producers have always been eager to know the reasons for the difference in the production of different shale gas wells. The Southern Sichuan Basin in China is one of the main production zones of Longmaxi shale gas, while the shale gas production is quite different in different shale gas wells. The Longmaxi formation was deposited in a deep water shelf that had poor circulation with the open ocean, and is composed of a variety of facies that are dominated by fine-grained (clay- to silt-size) particles with a varied organic matter distribution, causing heterogeneity of the shale gas concentration. According to the different mother debris and sedimentary environment, we recognized three general sedimentary subfacies and seven lithofacies on the basis of mineralogy, sedimentary texture and structures, biota and the logging response: (1) there are graptolite-rich shale facies, siliceous shale facies, calcareous shale facies, and a small amount of argillaceous limestone facies in the deep - water shelf in the Weiyuan area and graptolite-rich shale facies and carbonaceous shale facies in the Changning area; (2) there are argillaceous shale facies and argillaceous limestone facies in the semi - deep - water continental shelf of the Weiyuan area and silty shale facies in the Changning area; (3) argillaceous shale facies are mainly developed in the shallow muddy continental shelf in the Weiyuan area, while silty shale facies mainly developed in the shallow shelf in the Changning area. Judging from the biostratigraphy of graptolite, the sedimentary environment was different in different stages.

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.

Accumulation Conditions of Paleozoic Shale Gas and its Resources in Northeast Chongqing Areas

2013 ◽  
Vol 868 ◽  
pp. 186-191 ◽  
Author(s):  
Sheng Ling Jiang ◽  
Chun Lin Zeng ◽  
Sheng Xiu Wang ◽  
Mei Li
Keyword(s):  
Shale Gas ◽  
Lower Cambrian ◽  
Source Rocks ◽  
Organic Carbon Content ◽  
Upper Ordovician ◽  
Longmaxi Formation ◽  
Lower Silurian ◽  
Reservoir Conditions ◽  
High Maturity ◽  
High Organic Carbon Content

In order to carry out a more comprehensive discussion on shale gas accumulation conditions of Lower Cambrian Shuijingtuo Formation and Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation, the distribution, source rock conditions and reservoir conditions of these two shales are comprehensively analyzed, these two shales are both have the characteristics of high organic carbon content, high maturity, appropriate thickness and mainly typeⅠkerogen as source rocks, and interbedded with siltstone and/or fine sandstone, rich in quartz and other detrital components, easy to break and form the cracks, micro cracks as reservoirs, these characteristics provide a favorable material basis and reservoir space for shale gas accumulating. On this basis, the effective distribution areas of these two shales are further determined and shale gas resources are preliminary evaluated, eventually come to the results of shale gas resources of Lower Cambrian Shuijingtuo Formation and Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation respectively are 0.409×1012m3and 0.389×1012m3.

scholarly journals Development Characteristics of Shale Lithofacies in the Longmaxi Formation and their Main Controlling Factors in the Changning Area, South Sichuan Basin, SW China

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingsong Tang ◽  
Lu Zhou ◽  
Lei Chen ◽  
Xiucheng Tan ◽  
Gaoxiang Wang
Keyword(s):  
Seismic Data ◽  
Sichuan Basin ◽  
Spatial Variations ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
Longmaxi Formation ◽  
X Ray ◽  
Lower Silurian ◽  
Longmaxi Shale ◽  
Siliceous Shale

Based on core observations, thin sections, X-ray diffraction (XRD), and seismic data, the lithofacies types in the organic-rich Longmaxi shale (Lower Silurian) in the Changning area of the southern Sichuan Basin were identified. The factors controlling the spatial variations in the shale lithofacies and the influences of the shale lithofacies on shale gas development were also analyzed. Results indicate that there are seven main types of shale lithofacies in the Long11 sub-member of the Longmaxi Formation, including siliceous shale (S-1), mixed siliceous shale (S-2), carbonate-rich siliceous shale (S-3), clay-rich siliceous shale (S-4), carbonate/siliceous shale (M-1), mixed shale (M-2), and argillaceous/siliceous shale (M-4). A vertical transition from the carbonate shale association + mixed shale association at the bottom of the sub-member to a siliceous shale association and mixed shale association + siliceous shale at the top generally appears in the Long11 sub-member. The shale lithofacies of the Long11 sub-member also laterally change from the central depression (low-lying area) to the geomorphic highland in the east and west parts of the Changning area. The spatial variations in shale lithofacies in the Long11 sub-member of the Changning area were mainly controlled by palaeogeomorphology and relative sea level. The geomorphic highland area is dominated by carbonate-rich siliceous shale and mixed siliceous shale, but the depression (low-lying area) is mainly dominated by mixed siliceous shale and argillaceous/carbonate shale.

scholarly journals Reservoir Characteristics of the Lower Silurian Longmaxi Shale in Zhaotong Region, Southern China

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Chao Luo ◽  
Nanxin Yin ◽  
Hun Lin ◽  
Xuanbo Gao ◽  
Junlei Wang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Shale Gas ◽  
Southern China ◽  
Gas Content ◽  
High Quality ◽  
Longmaxi Formation ◽  
Lower Silurian ◽  
Longmaxi Shale ◽  
Scanning Electron

The lower Silurian Longmaxi Formation hosts a highly productive shale gas play in the Zhaotong region of southern China. According to core observation, X-ray diffraction analyses, and scanning electron microscopy (SEM) observations, the shale comprises primarily quartz, carbonate minerals, and clay minerals, with minor amounts of plagioclase, K-feldspar, and pyrite. The clay mineral content ranges from 15.0% to 46.1%, with an average of 29.3% in the Zhaotong region. Organic geochemical analyses show that the Longmaxi Formation has good potential for shale gas resources by calculating total organic carbon, vitrinite reflectance, and gas content. Scanning electron microscope images demonstrate that reservoir pore types in the Longmaxi shale include organic pores, interparticle pores, intercrystalline pores, intraparticle pores, and fractures. Reservoir distribution is controlled by lithofacies, mineral composition, and geochemical factors. In addition, we investigated the relationships between reservoir parameters and production from 15 individual wells in the Zhaotong region by correlation coefficients. As a result, the brittleness index, total organic carbon (TOC), porosity, and gas content were used to define high-quality reservoirs in the Longmaxi shale. Based on these criteria, we mapped the thickness and distribution of high-quality reservoirs in the Longmaxi Formation and selected highlighted several key sites for future exploration and development.

Geological Conditions of Shale Gas of the Upper Ordovician Wufeng Formation - Lower Silurian Gaojiabian Formation in Lower Yangtze Area

2013 ◽  
Vol 448-453 ◽  
pp. 3737-3741
Author(s):  
Shuai Shuai Yang ◽  
Wei Jiang ◽  
Fei Cai ◽  
Jian Dong Hu ◽  
Jiang Li
Keyword(s):  
Organic Carbon ◽  
Shale Gas ◽  
Sedimentary Environment ◽  
Organic Matter Content ◽  
Mature Stage ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Geological Conditions ◽  
Lower Yangtze ◽  
Yangtze Area

According to the outcrop, well data, geochemical and reservoir property in lower Yangtze area. This paper analyses the sedimentary environment, thickness, distribution, buried depth, organic matter content and types, maturity and reservoir characteristics of shale in WufengGaojiabian Formation of Upper Ordovician to Lower Silurian. The shale is formed in shelf sedimentary environments with large thickness and moderate depth. WufengGaojiabian Formation contains 0.5% to 1.0% of organic carbon, consistent with typeIandII kerogen. The Ro in rang of 1.5%~2.5%, indication high mature to over mature stage for gas generation. It has high brittleness of mineral content in this set of shale with rich micro-fracture. The thickness of shale, buried depth, organic carbon and maturity shows that GaoyouHaianJurong of Northern Jiangsu, JingxianNingguo of Southern Anhui, Linan of Western Zhejiang areas are considered favorable zones for shale gas formation.

scholarly journals Characteristics of Mineralogy, Lithofacies of Fine-Grained Sediments and Their Relationship with Sedimentary Environment: Example from the Upper Permian Longtan Formation in the Sichuan Basin

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3662
Author(s):  
Hongzhi Yang ◽  
Liangbiao Lin ◽  
Liqing Chen ◽  
Yu Yu ◽  
Du Li ◽  
...  
Keyword(s):  
Mineral Composition ◽  
Sichuan Basin ◽  
Sedimentary Environment ◽  
Organic Matter Content ◽  
Upper Permian ◽  
Carbonaceous Shale ◽  
Carbonate Minerals ◽  
Thin Sections ◽  
Terrestrial Input ◽  
The Sichuan Basin

The Longtan Formation of the Upper Permian in the Sichuan Basin has become a significant target for shale gas exploration in recent years. Multiple methods, including outcrop observations, thin sections, total organic matter content, X-ray diffraction and scanning electron microscopy were used to investigate the mineralogy, shale lithofacies assemblages and their relationships with the deposition environment. The mineral composition of the Longtan Formation has strong mineral heterogeneity. The TOC values of the Longtan Formation have a wide distribution range from 0.07% to 74.67% with an average value of 5.73%. Four types of shale lithofacies assemblages of the Longtan Formation could be distinguished, as clayey mudstone (CLS), carbonaceous shale (CAS), siliceous shale (SS) and mixed shale (MS) on the basis of mineral compositions. The TOC values of various types of shale lithofacies assemblages in the Longtan Formation varied widely. The shore swamp of the Longtan Formation is most influenced by the terrestrial input and mainly develops CLS and MS. The tidal flat is influenced by the terrestrial input and can also deposit carbonate minerals, developing CLS, CAS and MS. The shallow water melanged accumulation shelf develops CAS and MS, dominated by clay and carbonate minerals. The deep water miscible shelf develops CLS and SS, whose mineral composition is similar to that of the shore swamp, but the quartz minerals are mainly formed by chemical and biological reactions, which are related to the Permian global chert event. The depositional environment of the Longtan Formation controls the shale mineral assemblage of the Longtan Formation and also influences the TOC content.

scholarly journals Comparison of source rocks from the Lower Silurian Longmaxi Formation in the Yangzi Platform and the Upper Devonian Semiluksk Formation in East European Platform

2021 ◽  
Vol 2 (1) ◽  
pp. 63-72
Author(s):  
V.P. Morozov ◽  
Zhijun Jin ◽  
Xinping Liang ◽  
E.A. Korolev ◽  
Quanyou Liu ◽  
...  
Keyword(s):  
East European Platform ◽  
Upper Devonian ◽  
Source Rocks ◽  
Longmaxi Formation ◽  
East European ◽  
Lower Silurian

scholarly journals Total Porosity Measured for Shale Gas Reservoir Samples: A Case from the Lower Silurian Longmaxi Formation in Southeast Chongqing, China

Minerals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 5 ◽  
Author(s):  
Fangwen Chen ◽  
Shuangfang Lu ◽  
Xue Ding ◽  
Hongqin Zhao ◽  
Yiwen Ju
Keyword(s):  
Shale Gas ◽  
Clay Content ◽  
Total Porosity ◽  
Gas Reservoir ◽  
Longmaxi Formation ◽  
Fine Grained ◽  
Average Value ◽  
Lower Silurian ◽  
Shale Gas Reservoir ◽  
Research Institute

Measuring total porosity in shale gas reservoir samples remains a challenge because of the fine-grained texture, low porosity, ultra-low permeability, and high content of organic matter (OM) and clay mineral. The composition content porosimetry method, which is a new method for the evaluation of the porosity of shale samples, was used in this study to measure the total porosity of shale gas reservoir samples from the Lower Silurian Longmaxi Formation in Southeast Chongqing, China, based on the bulk and grain density values. The results from the composition content porosimetry method were compared with those of the Gas Research Institute method. The results showed that the composition content porosimetry porosity values of shale gas reservoir samples range between 2.05% and 5.87% with an average value of 4.04%. The composition content porosimetry porosity generally increases with increasing OM and clay content, and decreases with increasing quartz and feldspar content. The composition content porosimetry results are similar to the gas research institute results, and the differences between the two methods range from 0.05% to 1.52% with an average value of 0.85%.

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