scholarly journals Reservoir characteristics in the Cretaceous volcanic rocks of Songliao Basin, China: A case of dynamics and evolution of the volcano-porosity and diagenesis

2018 ◽  
Vol 37 (2) ◽  
pp. 607-625 ◽  
Author(s):  
Haitao Sun ◽  
Dakang Zhong ◽  
Weijia Zhan

To explain the strong spatial heterogeneity of volcanic reservoirs porosity in the Songliao Basin and provide new ideas for predicting good volcanic reservoirs in other similar basins, the relationship between the pore evolution process and lithology of volcanic reservoirs has been described in this article. With the description and interpretation of core, thin section, scanning electron microscope, and the results of mercury injection experiment, this article clarifies the lithology, pore types, and pore structure features of the volcanic reservoirs in the Songliao Basin. The rocks of volcanic reservoirs in study area contain pyroclastic rock and volcanic lavas. The most common lithologies are rhyolite, volcanic breccia, and volcanic tuff. The pore size, morphology, and structure vary greatly between these three lithologies, the reason of which we think is the different volcanic eruption process as well as rock composition and its structure. The digenetic evolution of rhyolite includes gas dissipation of magmatic condensation; vesicles fulfilling by hydrothermal fluid; kaolinization and sericitization of feldspar phenocrysts; carbonation, devitrification, and recrystallization of felsic matrix; and finally, the dissolution of feldspar phenocrysts and felsic matrix. As for volcanic breccia, it usually go through the compaction, quartz and calcite filling the original pores between volcanic breccias, and dissolution of mineral debris together with tuff matrix. Similar with the rhyolite, volcanic tuff also undergoes the carbonation and kaolinization of felsic matrix, the dissolution of feldspar and felsic matrix, and compaction. Due to these comprehensive processes, a comprehensive analysis of volcanic rock lithology, which can indicate lithology distribution vertically and horizontally, is very necessary during volcanic reservoirs evaluation and prediction. These detailed analyses will help explorers to find potential reservoirs by distinguishing the diagenetic evolution and pore characteristic of volcanic reservoirs.

2017 ◽  
Vol 35 (3) ◽  
pp. 295-314 ◽  
Author(s):  
Shizhen Tao ◽  
Changwei Li ◽  
Weijiao Ma ◽  
Deliang Liu ◽  
Jingkui Mi ◽  
...  

Volcanic reservoirs are extensive in the Songliao Basin and mainly include intermediate-basic rocks in the northern part, intermediate-acidic rocks in Xujiaweizi in the southern part, and acidic rocks in the Jinglin block. The natural gas in the volcanic reservoirs of the Songliao Basin has a wide range of compositions, with alkanes being dominant in most cases, although carbon dioxide is dominant in some wells. Generally, the gas in the volcanic rocks near deep faults has high contents of carbon dioxide, whereas the natural gas in volcanic rocks far from faults has low carbon dioxide contents. The gas in the volcanic reservoirs is of multiple origins, including abiogenic gas of probable mantle origin (generally found in wells with high carbon dioxide contents) and organic gas mainly derived from organic matter in the basin. The abiogenic alkanes have δ13C values in the order of δ13C1 > δ13C2 > δ13C3 > δ13C4, which is opposite that of alkanes of organic origin. The 3He/4He ratios of the fluid inclusions from the volcanic reservoirs range from 0.286 × 10−6 to 7.33 × 10−6, with an average of 2.48 × 10−6, and the R/Ra ratios range from 0.26 to 5.24, with most values being greater than 1.0, indicating mixed origins of noble gases from the crust and the mantle. The gas in fluid inclusions from the volcanic reservoirs has δ13C1 values ranging from −17.1 to −28.7‰ (PDB), δ13C2 values ranging from −23.4 to −32.4‰ (mostly approximately −25‰), and δ13Cco2 values ranging from −10.97 to −21.73‰, which are significantly different from the isotopic compositions of the gas in the present reservoirs, suggesting that some abiogenic alkanes may have been charged into the reservoirs during the geologic history of the basin. The early charged CO2 is mainly organic in origin, while the abiogenic CO2 was charged during the main accumulation period, producing a mix of origins for the gas in the volcanic reservoirs of the Songliao Basin. The abiogenic alkanes, He, and CO2 in the natural gas indicate the addition of some abiogenic gas to the gas. According to the relationship between the distribution and attitude of volcanic rocks and faults, we found that the abiogenic gas reservoirs are located near fault zones, whereas the organic and mixed gas reservoirs are located far from fault zones. The geochemical study of natural gas is helpful in determining the origin and spatial distribution patterns of gas in deep volcanic reservoirs and for directing further gas exploration in the Songliao Basin.


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Fancheng Zeng ◽  
Bo Liu ◽  
Changmin Zhang ◽  
Guoyi Zhang ◽  
Jin Gao ◽  
...  

Tight gas sandstone and volcanic gas reservoirs have received global attention in the energy arena for further exploration and exploitation attempts. Considering the Yingcheng Formation of Dehui fault depression in the Songliao Basin as an example, this study focused on the accumulation and distribution of natural gas reservoirs in volcanic area in a fault depression basin. Volcanic activities occurred in the Yingcheng Formation, which is distributed centrally in the northwest of the study area. During the sedimentation of the Yingcheng Formation, fan-delta, lacustrine, and nearshore subaqueous fan facies were deposited. The source rocks of the Yingcheng Formation have high abundance of organic matter mainly in type III at high-overmature stages, indicating favorable conditions for gas production. The porosity of volcanic reservoir is 3.0%-14.8%, the permeability is 0.0004 mD-2.52 mD, and the pore types are mainly secondary dissolved pores and fractures. Besides, the porosity of the tight sandstone reservoir is 0.5%-11.2%, and the permeability is 0.0008 mD-3.17 mD. The pore types are mainly interparticle pores, with a small proportion of intraparticle pores and microfractures. The intrusion of late volcanic magma provided sufficient heat for the thermal maturity progression of organic matter in Yingcheng Formation and promoted the generation of natural gas in large quantities. Volcanic rocks formed at the early and middle stages of volcanic activities occupied the sedimentary space and hindered the development of sedimentary sand bodies to a certain extent. However, volcanic rocks can become the seal to promote the formation of tight sandstone gas traps. Comparing tight sandstone reservoirs with volcanic ones, the latter are less affected by compaction; thus, their petrophysical properties do not vary much with depth, showing more homogeneous characteristics. The pyroclastic rocks influenced by volcanic activity and the secondary pores formed by dissolution in the later stages also provide reservoir space for gas accumulation. Ultimately, the tight sandstone and volcanic rocks in the study area form a complex gas reservoir system, which can become a reference for exploration and exploitation of natural gas in other petroliferous fault depressions that are affected by volcanisms.


2013 ◽  
Vol 868 ◽  
pp. 101-106 ◽  
Author(s):  
Xu Yan ◽  
Hai Tao Xue

Wangfu fault depression Huoshiling Formation in southern Songliao Basin volcanic rocks with larger gas potential, but the volcanic reservoir control factors is not clear, the author take Well Wangfu 1 for example, explore the Huoshiling Formation of volcanic rock reservoir control factors. Well Wangfu 1 main lithology is andesite, volcanic breccia and tuff;on the lithofacies is given priority to with the overflow facies, followed by eruption facies, a small amount of volcanic sedimentary facies; denudation, devitrify and tectonism have the significance on improving reserving space; gaps in the tuff to improve large reservoir, it is more obvious that andesite and volcanic breccia improving permeability; volcanic breccia of Well Wangfu 1 is the relatively favorable reservoir space.


Author(s):  
A.I. Malinovsky ◽  
◽  
V.V. Golozubov ◽  

This paper studies the original results of the material composition analysis of the Early Silurian terrigenous deposits of the Kordonka formation of the Paleozoic – Early Mesozoic Laoeling-Grodekovo terrane of the South Primorye. The research is aimed at reconstructing paleogeodynamic setting of the deposition of sediments of the formation, and determining the type and mother rock composition of the feed sources based on the complex genetic interpretation of the material composition of rocks. It was established that mineralogically and geochemically formation of the rocks correspond to the typical graywackes and represent petrogenic or “first cycle” rocks formed mainly through the source rock failure. They are characterized by a low maturity, low lithodynamic recycling rate of mother rocks and their rapid burial. The interpretation of the results of the complex study of the material composition of the rocks was carried out on the basis of its comparison with the compositions of ancient rocks and modern sediments formed in the well-known geodynamic settings. The obtained data indicate that deposits of the Kordonka formation accumulated in a sedimentary basin connected with an oceanic island arc. Being built by basic and intermediate volcanic rocks as well as by igneous and sedimentary rocks that constituted its base, this island arc was the source area that supplied clastic material to the aforementioned sedimentary basin.


2020 ◽  
Author(s):  
Suwijai Jatupohnkhongchai ◽  
Sirot Salyapongse ◽  
Burapha Phajuy ◽  
Daniela Gallhofer ◽  
Christoph Hauzenberger

<p>A series of pyroclastic rocks are mapped as a Silurian-Devonian unit in the Kanchanaburi-Uthai Thani area, Western Thailand, which belongs to the Inthanon Zone. These pyroclastic rocks were discovered and described for the first time in 1977 and mentioned in the 1:250,000 Suphanburi geologic map sheet and report. Since then these rocks were poorly investigated and their formation and geotectonic setting is unclear. As a result, we report petrographic, geochemical and geochronological data of these pyroclastic rocks. Petrographically, the pyroclastic rocks can be described as a meta-quartz-K-feldspar crystal tuff, a meta-quartz crystal tuff, and a meta-lithic tuff. They are made up of mm sized clasts in a finely grained matrix. The clasts consist of potassium feldspar, rounded quartz, embayed quartz, trachytic and metasedimentary rock clasts embedded in a highly altered devitrified fine-ash matrix containing sericite.</p><p>The whole-rock composition shows enrichments in SiO<sub>2</sub> and K<sub>2</sub>O and a strong depletion in CaO and Na<sub>2</sub>O which is related to late alteration of the volcanoclastic rocks. Based on the immobile element classification plot of Pearce 1996, the tuffs can be classified as trachyandesite, trachyte, dacite and rhyolite. Their chondrite-normalized REE patterns display light REE enrichment with nearly flat heavy REE and a negative Eu anomaly, typical for calcalkaline volcanic rocks. Most samples fall in the volcanic arc granites field in the granite discrimination diagrams of Pearce 1984.</p><p>Zircons extracted from the tuffs will be used to constrain their crystallization age by U-Pb LA-MCICPMS dating. This allows us to constrain the age of formation and to place this in context with the closure of the Paleotethys.</p>


2012 ◽  
Vol 22 (01n02) ◽  
pp. 157-164
Author(s):  
AGNES G. REYES ◽  
WILLIAM J. TROMPETTER ◽  
IAN J. GRAHAM

Rocks and melt inclusions (MI) from 11 volcanic centers of the Kermadec-Tofua arc, in the South West Pacific, were petrographically studied prior to chemical analysis under the ion beam. The abundance of MI with daughter minerals are volcano-specific with the most abundant found in "U", Putoto, and Hinepuia volcanoes where >50% of MI contain daughter minerals. The B , Li , Cl and S contents in MI generally increase with the silica content of the rock. Fe , Ni , Mn , Cu and Zn are common in MI of all rock types but Mo , Hg and Cu have the highest concentrations in dacite-rhyodacites. The highest concentrations of B , Ti , V , Fe , Co and Mo occur in plagioclase MI; S , Ni , Ge and Hg in pyroxene MI; Cl and Li in quartz MI; and Cu , Zn and M in hornblende MI. Different ore-forming components in volcanic rocks can be correlated with rock composition, Cl/S and B/S of the melts, the presence and abundance of mineral sinks for various elements and the occurrence of hydrothermally altered rock at depth and on the seafloor.


2018 ◽  
Vol 6 (2) ◽  
pp. T431-T447 ◽  
Author(s):  
Xiaoming Sun ◽  
Siyuan Cao ◽  
Xiao Pan ◽  
Xiangyang Hou ◽  
Hui Gao ◽  
...  

Volcanic reservoirs have been overlooked for hydrocarbon exploration for a long time. Carboniferous volcanic rocks of the Zhongguai paleouplift contain proven reserves of [Formula: see text]. We have investigated the volcanic reservoirs integrating cores, well, and seismic data, and the proposed volcanic reservoir distribution is controlled by the weathering function, fractures, and lithology. The weathering process makes the originally tight igneous rocks become good-quality reservoirs, and fractures play an important role in connecting different types of pores and act as reservoir space. Isolated and ineffective pores become effective ones due to connection among fractures. Only volcanic breccia can be good-quality reservoirs without any weathering function. The nonlinear chaos inversion controlled by weathered layers shows that the good-quality reservoirs are distributed in the top of the weathering crust and the structural high. Furthermore, fluid-detection attributes and background information prove that oil and gas are distributed along the paleostructural high. The objectives of this study were to (1) describe the characteristics of volcanic reservoirs and determine the controlled rules for reservoir distribution, (2) characterize the distribution of reservoirs and hydrocarbon, and (3) propose an effective workflow for hydrocarbon exploration in volcanic rocks combining geologic and geophysical methods.


2004 ◽  
Vol 41 (2) ◽  
pp. 165-182 ◽  
Author(s):  
Pierre A Friele ◽  
John J Clague

Mount Meager massif, the northernmost volcano of the Cascade volcanic belt, has been the site of very large (>107 m3) landslides in the Holocene Epoch. We document two complex landslides at Pylon Peak, one of the peaks of the Mount Meager massif, about 7900 14C and 3900 14C years ago (about 8700 and 4400 calendar years ago). Together, the two landslides displaced ~ 6 × 108 m3 of volcanic rock from the south flank of Pylon Peak into nearby Meager Creek valley. Each landslide consisted of at least two phases, an early debris flow resulting from failure of hydrothermally altered pyroclastic rock at mid levels on the mountain and a later rock avalanche from a higher source. Both debris flows likely traveled down Meager Creek, and preliminary evidence from drilling indicates the 4400-year-old event traveled down Lillooet River into areas that are now settled and where population density is increasing rapidly. The mobility of the debris flows was due to the high content of fine, weathered volcanic sediment and the availability of sufficient water. The causes of the landslides are a wet climate and the presence of weak, hydrothermally altered volcanic rock containing abundant phreatic water on glacially oversteepened slopes. The landslides may have been triggered by earthquakes or by upwelling of magma to shallow depths within the volcano. However, they may also have occurred without specific triggers following extended periods of progressive weakening of the volcanic rocks.


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