Hailar Basin Research Articles

Influence of multi-trend major fault reactivation during multiphase rifting: Beier Depression, Hailar Basin, NE China

AbstractComplex fault patterns associated with rift development in the Hailar Basin were largely influenced by the Mongolia–Okhotsk Ocean and Palaeo-Pacific tectonic regimes during the Late Jurassic to Early Cretaceous periods. Based on 3D seismic data from the Beier Depression in the Hailar Basin, we characterized the reactivation history of multi-trend major faults and examined the evolution of the Beier Depression during the Early Cretaceous period. NE–SW-, NW–SE- and ENE–WSW-oriented major faults originated from strike-slip-associated structures that were pre-existing fabrics and then were reactivated and propagated upward under extensional regimes in the Late Jurassic. During the syn-rift stage (K1t–K1n), the Hailar Basin was in a NNW–SSE- to NW–SE-oriented extensional setting, and major faults of all orientations were active. There was tectonic quiescence (K1n1L) between the syn-rift stages (a rifting transition stage). The short compression stage after the syn-rift stage caused regional compressional deformation. During the post-rift stage (K1d–K1y), the extension direction rotated to an E–W orientation, and a new population of N–S-trending faults formed together with the reactivation of NE–SW- and ENE–WSW-trending major faults. Structural analysis shows that the major ENE–WSW-trending major faults were polycyclic growth faults reactivated via an upward propagation mode and that the NE–SW-trending faults were dip linkage faults reactivated via a dip linkage mode. The reactivation intensity of the NE–SW-trending major faults was stronger than that of the ENE–WSW-trending major faults. These results demonstrate the differences in the evolution of the different trending faults in the same tectonic regime, and the complexity of the final fault patterns in the Beier Depression was produced by differences in the reactivation of major faults. The originate interpretation of the multi-trend major faults in the Hailar Basin provides new insights into fault generation, and the classification of fault growth also has useful implications for future research on multiphase rifts.

Dawsonite as a Temporary but Effective Sink for Geological Carbon Storage

The possibility of using dawsonite mineral trapping as a carbon capture and storage (CCS) strategy intrigues many. In this study, we used a dawsonite-rich (∼10%) CO 2 gas reservoir in the Hailar basin in northern China as a natural analogue of a CO 2 storage site, along with numerical modeling, to demonstrate that a large amount of dawsonite can be generated in sandstone formations, provided sufficient Na-rich feldspar and CO 2 gas are available. While precipitated dawsonite can be preserved only in a hydrodynamically-closed system in the long term under high CO 2 fugacity and log((Na + )/(H + )) activities in solution, short-term trapping of CO 2 in dawsonite (on the order of 10 kyr) is possible and lowers CO 2 pressure, which mitigates the risk of CO 2 leakage to the ground surface or overlying drinking water aquifers. The re-dissolution of dawsonite after a few thousand years facilitates progressive dissipation of the gas phase CO 2 over time. Consideration of reservoirs or saline aquifers with minerals or formation water that can provide a high abundance of dissolved sodium, significantly increases the number of potential CCS sites globally. Furthermore, alternating water-and-gas injection regimens could enhance the precipitation of dawsonite in Na-rich aquifers. Future editions of the Carbon Storage Atlas should consider aquifer geochemistry in the site selection for secure long-term carbon storage in addition to the volumetric considerations for short-term operation.

The depositional model of the Lower Cretaceous Nantun Formation and its implications for oil accumulation in the northern Wuerxun Sag of Hailar Basin, NE China

The northern Wuerxun Sag is a lacustrine rift basin which experienced multiple faulting and subsidence during the Lower Cretaceous. The tectonic evolution with uplifted regions as the provenances caused the complex sedimentary fill of the Lower Cretaceous Nantun Formation. In this paper, we use well log, core and 3D seismic data to characterise the sedimentary facies and depositional environment of the Nantun Formation, and consider how this affects the distribution of hydrocarbons within the basin. Four depositional systems are recognised in this study: fan deltas located along the steep slopes; braided deltas along the gentle slopes; sublacustrine fans and lacustrine in the centre of the basin. Fan deltas are mainly composed of coarser sediments with lower sediment maturity than braided deltas, and are mainly located in steep slopes with rift border faults. Sublacustrine fans form lenticular depositional bodies in the basin centre, with higher sediment maturity as a result of reworking. Three sediment-transport pathways were recognised which governed the sediment deposition in this basin, which are (1) the steep rift border fault in the northwest, (2) the NE–SW Surennuoer strike-slip fault zone (SSFZ), and (3) the major faults in the south-eastern gentle slope. Most oil is found in sublacustrine fan sandstones which were transported along the SSFZ mainly from shallower fan deltas, with underlying mudstones (SQN1) as effective source rocks and overlying thick and laterally continuous lacustrine mudstones (SQD1) as seal rocks. The good source–reservoir–seal assemblages enable prolific near-source oil distribution in this area, suggesting the sedimentary controls on oil accumulation, which may guide future oil exploration and production activities in this area.

Palaeoecology and palaeoclimate of an Early Cretaceous peat mire in East Laurasia (Hailar Basin, Inner Mongolia, China)

In this contribution, we report the palynology, organic petrography and carbon isotopes for the #16 Seam in the Lower Cretaceous Yimin Formation of the Hailar Basin, Inner Mongolia, China. Eighteen palynological samples were collected from the coal seam as well as from intraseam partings and the immediate roof. Microfloras comprise a diverse assemblage of ferns, conifers, horsetails, lycopsids, bryophytes, ginkgoes and cycads. Conifer pollen is common, especially representative of Pinaceae (Pinuspollenites) as well as Cheirolepidiaceae (Classopollis) and Araucariaceae (Araucariacites, Chasmatosporites); however, this material is interpreted as mostly derived from an upland source rather than from the mire-forming vegetation. An overrepresentation of conifer pollen may explain the relatively poor abundance and diversity of ginkgo and cycad pollen, compared to what is found in the macrofossil record. The palynological assemblage found in Seam #16 indicates a Barremian to Aptian age. Maceral composition, ash yields, and δ13Corg signature of the coal suggest peat accumulation was controlled by a rising water table from flooding of the mire, coupled with significant ground (peat) fires and/or surface wildfires. These conditions resulted in high levels of detrital mineral matter and charcoal input, the latter represented by inertodetrinite in the coals. The top of the coal seam is characterised by a higher ash yield, lower δ13Corg values and increased sphagnacean spores, which suggest the gradual drowning of the palaeomire. Although angiosperms were present in the Hailar Basin during the time that Seam #16 was accumulating, they are absent from the pollen found in this study. This may indicate that they were not yet adapted to the extreme conditions of the mire (e.g., acidity, anoxia), and unable to compete with the established mire vegetation.

Formation mechanism and accumulation model of primary condensate reservoir in Hailar Basin, NE China

Formation mechanism and accumulation model of primary condensate reservoir in Hailar Basin, NE China

Climate characteristics of the eastern Mongolian Plateau, China during the early Early Cretaceous (145–132 Ma): Palynological evidence from the Tongbomiao Formation in Well Hong-6, Hailar Basin

This study identified two palynological assemblages, namely Bayanhuasporites-Cycadopites-Protoconiferus and Cicatricosisporites-Cedripites-Perinopollenites, in the Tongbomiao Formation in the Hongqi Sag in the Hailar Basin, Inner Mongolia, China for the first time. The former is distributed in the lower part of the Tongbomiao Formation and is characterized by abundant gymnosperm pollen and diverse fern spores. Among them, the gymnosperm pollen is dominated by Paleoconifer (4.98%–31.62%) and Cycadopite (8.55%–25.23%) pollen grains and also includes other pollen grains such as Classopollis, Parcisporites, Erlianpollis, Callialasporites, and Jiaohepollis. The fern spores in the former palynological assemblage contain Bayanhuasporite (0–8.96%), Granulatisporites (0.93%–6.97%), and some important Cretaceous genera, such as Cicatricosisporites, Concavissimisporites, Densoisporites, Hsuisporites, Foraminisporis, and Leptolepidites. The Cicatricosisporites-Cedripites-Perinopollenites palynological assemblage is distributed in the upper part of the Tongbomiao Formation. Gymnosperm (77.30%), Pinaceae (31.9%), and Paleoconiferus (19.02%) pollen predominate this palynological assemblage, and Quadraeculina, Erlianpollis, and Jiaohepollis pollen are also common in this assemblage. The fern spores in this palynological assemblage include abundant Cicatricosisporites (4.29%). Besides, Concavissimisporites, Aequitriradites, and Leptolepidites are also common in this palynological assemblage. No angiosperm pollen has been found in both palynological assemblages. The identification of both palynological assemblages provides important evidence for the biostratigraphic correlation between the Hailar Basin and its adjacent areas. It also enables the reconstructions of the Berriasian-Valanginian (Early Cretaceous) vegetation and the paleoclimate on the eastern Mongolian Plateau during 141–132 Ma. The vegetation reconstructed on the palynological data of the represented by Hailar Basin in eastern Mongolian Plateau (141.6–141.4 Ma), form conifer forest or conifer broad-leaved mixed forest to conifer forest with shrubs and grassland, the climate belongs to warm temperate and warm-subtropicalt, the highest temperature is estimated to reach 35–38°C. Form 132.3 Ma, the vegetation type is conifer forest, and its paleoclimate is sub-humid warm temperate, the highest temperature is estimated to reach 24–29°C.©2022 China Geology Editorial Office.

Structural characteristics and formation mechanisms of Bayanhushu Sag in Hailar Basin, north‐east China: A study based on structural physical simulation

The Hailar Basin, located in north‐east China, is a typical continental rifted basin that contains oil and gas. The basin formation process comprised several stages of construction and reformation with complex formation mechanisms. The Bayanhushu (BYHS) Sag is a secondary structural unit in the south‐west Hailar Basin with a significant resource potential, but its current poor exploration and insufficient understanding of the structural evolution characteristics are restricting further oil and gas exploration. Therefore, the study of the structural evolution of the BYHS Sag plays a pivotal role in the future exploration and development of oil and gas. There are different hypotheses on the formation mechanisms and structural evolution of the BYHS Sag. To further understand the evolutionary history of the BYHS Sag, a structural physical simulation experiment was used based on the structural interpretation and geometric analysis of a seismic section. Inversion validation was then undertaken by the 2DMove equilibrium profile recovery technology. It was found that the formation process of the BYHS Sag was mainly controlled by the western Adunchulu Fault. Faults on the section developed in succession from top to bottom. The fault plane experienced multiple changes, thus forming a special seat‐shaped structural pattern. Structural inversion occurred twice during the evolution of the sag. The compressive stress during the tectonic inversion mainly acted in a SE direction. It is inferred that this was related to the subduction of the Palaeo‐Pacific Plate under the Eurasian Plate and the intermittent compression caused by the transmission of stress of the arc–continent collision.

Geological controls on the natural CO2 accumulation in the Surennuoer Oilfield of the Hailar Basin, China

Naturally occurring CO2 often coexists with hydrocarbon accumulations on continental margins around the world, the presence of which may affect hydrocarbon production as a greenhouse gas. In this paper we focus on the natural CO2 in the Surennuoer Oilfield of the Hailar Basin, and investigate CO2 origin, distribution, related tectonic controls and accumulation mechanisms using geochemical, petrophysical and seismic data. Results show that the CO2 is of inorganic origin due to the degassing of magma from the deep crust or mantle, and is mainly stored in structural traps of N1 Member. There are close spatial and temporal relationships among CO2 distribution, major fault distribution and underneath igneous bodies, indicating a genetic link. The magmatic events and major faults are proposed to be the key controlling factors of CO2 distribution, which provided CO2 supply and migration pathways for both magma and degassed CO2. Additionally these faults also play a role in forming structural traps to store CO2. The sandstone reservoirs of low porosity and low permeability may play a limited role due to their poor reservoir quality. Two CO2 accumulation models are outlined in the Surennuoer strike-slip fault zone and the S3 fault zone. The former is characterized by shallower magmatic igneous body and a small amount of CO2 in the shallower N2 Member in addition to N1 Member. The Surennuoer strike-slip faults may have further channelled magma upwards which initially intruded along the basin-controlling fault, while the magma under the S3 fault zone did not migrate further upward along the S3 faults. Generally this study provides a detailed understanding of CO2 distribution, accumulation models and geological controls which may guide future hydrocarbon production in the study area.

Research on the Forecast Means of Large-Scale Multi-Branch Fracturing Capacity

In order to effectively improve the economic benefits of large-scale fracturing of the single well in tight reservoirs, avoid investment risks and raise development effects, research on the forecast means of large-scale multi-branch fracturing capacity is carried out. Large-scale fracturing has high costs and high investment risks, it is necessary to conduct relatively accurate forecast for the capacity after fracturing to reduce investment risks. On the basis of the single-well capacity data of 78 large-scale fracturing wells that have been put into production in the Hailar Basin, the geological, development and engineering factors affecting capacity were deeply analyzed and summarized. According to different applicable conditions, the theoretical derivation and polynomial linear regression methods are used; two different capacity forecast models of tight reservoir are given. These two forecast models are used, the error of capacity forecast results after fracturing is less than 15%, and the accuracy can meet the actual application requirements of the mine, therefore, this forecast method provides a powerful technical support for the promotion of large-scale fracturing technology and reducing economic risks.

Study on Pore Structure and Seepage Characteristics in Huhenuoren Oilfield

Pore structure and seepage characteristics have been studied in view of the problem of watercut rose rapidly in Nantun formation of huhenuoren oilfield of Hailar basin. Fan delta deposition with characteristics of close resource, rapidly accumulation results in pore distribution does not uniform, communication are weak. Throat distribution takes on dual peak. Left peak corresponds to smaller throat, which is invalid throat; Right peak corresponds to bigger throat, which is valid throat and seepage channel. There exists big difference in pore structure. Microanisotropy is very strong. Movable oil saturation is relatively low. Water relative permeability takes on convex shape. Strong water sensitivity and big Jamin effect brought about that injection water hard to displace oil below 1μm throat radius. The oil production above 1μm throat radius is about 77% of total oil production by NMR test. Throats above 1μm radius are preferred path of injection water, are the main reason for watercut rising rapidly.

Reservoir characterization and geological controls of the Lower Cretaceous sandstones in the northern Wuerxun Sag, Hailar Basin, China

The Lower Cretaceous sandstone reservoirs in the northern Wuerxun Sag host abundant hydrocarbon resources and natural CO2 gas. Reservoir quality and heterogeneity are regarded as significant factors affecting the hydrocarbon and CO2 distribution, which have not been comprehensively investigated. In this paper the characteristics of the reservoirs are studied using well log, core, thin section and petrophysical data, and related geological controls are discussed to analyse the factors responsible for the variable reservoir quality. Results show that the Lower Cretaceous sandstones mainly include common sandstones and dawsonite-bearing sandstones, characterized by variable grain size and poor sorting. That is probably caused by the rapidly variable sedimentary facies as a result of short multiple provenances and complex fault system. The reservoir quality is regarded as poor with general low-moderate porosity (ranging from 1.20% to 27.40%, with an average of 12.32%) and low permeability (ranging from 0.01 × 10−3μm2 to 1708.00 × 10−3μm2 with an average of 19.08 × 10−3μm2). The porosity and permeability generally decrease as the burial depth increases. However dawsonite cements have caused local heterogeneity as dawsonite-bearing sandstones are of lower porosity and permeability than comparatively deeper common sandstones. In general, tectonic and depositional evolution provided the heterogeneous lithologic distribution which is the material basis of the reservoir quality evolution. Diagenesis is proposed to be primarily responsible for the reduction of reservoir quality, with compaction being the most important mechanism volumetrically. Cementation also played a role in destroying reservoir quality, with dawsonite cements causing local heterogeneit and closely related to the presence of natural CO2 gas in the Surennuoer strike-slip fault zone. There is a genetic link among the dawsonite cements, inorganic CO2 gas degassed from the magmatic intrusion bodies and the Surennuoer strike-slip fault zone. Generally this study provides a better understanding of the reservoir quality in the northern Wuerxun Sag as well as related geological controls, which can guide subsequent hydrocarbon production activities in the study area.

Coal petrology of the Yimin Formation (Albian) in the Hailar Basin, NE China: Paleoenvironments and wildfires during peat formation

Coal seams preserve continuous and high-resolution records of paleoenvironments and wildfire events during peat accumulation. In order to elucidate wildfire characteristics and terrestrial climate changes during the time of peat accumulation, petrographic characteristics of coals in the Lower Cretaceous Yimin Formation (Albian) in the Jiuqiao Sag, Hailar Basin, NE China were studied. Coal petrology analysis shows that the studied coal seams are characterized by dominant huminite (average 80.0 vol.%, mmf-mineral matter free), secondary inertinite (average 19.9 vol.%, mmf), and a very low mineral content (average 0.8 vol.%). These results suggest that the coal developed under waterlogged conditions in raised, ombrotrophic mires. The occurrence of moderate inertinite values in the coals implies that wildfires were frequent during the Albian. Burning temperature, ranging from 273 to 379 °C inferred from inertinite reflectances, indicates that wildfires during the Albian were ground fires because of low plant heights. Vertical trends in inertinite and huminite compositional changes within the coal seams may reflect local-scale, cyclic fluctuations in wildfire occurrence during the development of the peat mires. The likely cause of these fluctuations was changes in temperature and rainfall. The presence of significant levels of inertinite in the coals and inferred high atmospheric oxygen levels suggest that the Albian was a highly fire-prone period in the Hailar Basin. The recurrent occurrences of palaeo-wildfires events in the studied succession in the Hailar Basin reinforce that fire was an important element affecting wetland biodiversity during the Albian, while diversification and spread of angiosperms was taking place globally. Increased surface runoff and erosion after the palaeo-wildfires in the Jiuqiao Sag during the Albian may have enhanced the flux and availability of nutrients and sediments washing into the fluvial, lacustrine, and marine systems, further contributing to the Albian dysoxic-anoxic events.

Reservoir characteristics and control factors of Tongbomiao formation in Hongqi sag

Hongqi sag is located in the north of Beiehur depression in Hailar Basin, which is a secondary structural unit in the peripheral depression of Hailar Basin, with great exploration potential. Based on SEM, conventional thin sheet, cast thin sheet, mercury pressure and physical property data, this paper discusses the reservoir characteristics, types and control factors of high quality reservoir in Tongbomiao formation, Hongqi sag, so as to provide a strong geological basis for the exploration of oil and gas in this area. The reservoir space of Hongqi sag is mainly composed of four types: primary intergranular pore, micro fracture, feldspar dissolution pore and debris dissolution pore. It is of the type of ultra low porosity and low permeability. Although Tongbomiao formation in Hongqi sag is of very low porosity and low permeability type, high quality reservoir is still developed, and its reason is mainly controlled by sedimentary environment, diagenesis and structural fracture.

Fracture evolution in oil-rich rhyolitic lavas of the Hailar Basin, northeastern China

Rhyolitic lavas can hold considerable oil exploration potential which is inferred to be controlled by fracture systems. The need for a better understanding of fracture properties and related petroleum systems for such rocks is the principal motivation of this study. We investigate the fracture evolution of this play type by an analysis of the Early Cretaceous oil-rich rhyolitic lava outcrops, located in the Hailar Basin, northeastern China, integrating multiscale fracture data from field investigation, optical microscopy, fluorescence imaging, and scanning electron microscopy. Six main types of volcanic-related and tectonism-induced fractures are identified. Aperture, spacing, and length of these fractures predominantly show power-law distributions, and in most cases, the dimension of these three parameters follows that columnar joints > platy cooling fractures ≈ tectonic fractures ≫ conjugate shear fractures ≫ perlitic fractures. In addition, the fracture orientation patterns are commonly predictable. Small fractures usually make significant porosity contribution and are excellent reservoir spaces, while large fractures control the permeability and act as channels. The early Early Cretaceous NW–SE extension (D2 of the five phases of basin deformation) dominated the fracture evolution of the lavas. Although the seal of the reservoir is probably not extensively damaged by the reactivation of fractures during the multistage deformation of the basin, the likelihood of reactivation of fracture sets C1, C3, and T1 needs to be carefully evaluated during the exploration and recovery, as the reactivation tendency factors (fa) of these sets are > 1 at a certain stage of deformation. We suggest that the observed patterns may be extrapolated to similar rhyolitic lavas in many parts of the world.

Rhenium\u2013osmium (Re\u2013Os) geochronology of crude oil from lacustrine source rocks of the Hailar Basin, NE China

Re–Os radiometric dating of crude oil can be used to constrain the timing of hydrocarbon generation, migration or charge. This approach has been successfully applied to marine petroleum systems; however, this study reports on its application to lacustrine-sourced natural crude oils. Oil samples from multiple wells producing from the Cretaceous Nantun Formation in the Wuerxun-Beier depression of the Hailar Basin in NE China were analysed. Subsets of the Re–Os data are compatible with a Cretaceous hydrocarbon generation event (131.1 ± 8.4 Ma) occurring within 10 Myr of deposition of the Nantun Formation source rocks. In addition, two younger age trends of 54 ± 12 Ma and 1.28 ± 0.69 Ma can be regressed from the Re–Os data, which may reflect the timing of subsequent hydrocarbon generation events. The Re–Os geochronometer, when combined with complementary age dating techniques, can provide direct temporal constraints on the evolution of petroleum system in a terrestrial basin.

Using carbon isotopes and organic composition to decipher climate and tectonics in the Early Cretaceous: An example from the Hailar Basin, Inner Mongolia, China

When conducted in tandem, organic petrography and isotopic analyses can be used to interpret regional tectonics and palaeoclimate within a global context. As an example, a sequence of lignite (vitrinite reflectance average = 0.27%) in the Lower Cretaceous Yimin Formation, Inner Mongolia, China, was investigated. The study area is within the intracratonic Hailar Basin and was situated at ~45°N palaeolatitude. Globally warm temperatures allowed temperate to tropical vegetation such as ferns, cycads and gymnosperms to form thick, laterally extensive palaeomires within the basin. Probabilistic assessment indicates that the lower, thick (~40 m) Seam #16 may have accumulated over a time span between 174 (P10) to 481 (P90) thousand years, whereas the thin (~6 m) overlying Seam #16 Upper took between 20 (P10) and 96 (P90) thousand years. Thermal sag processes were active in the basin during these time periods, with subsidence rates balanced to allow enough accommodation space to accumulate thick peat, but not so fast as to induce flooding and burial by clastics. A high proportion of fossil charcoal (‘inertinite’) in both seams indicate that throughout the peat-forming period, fire was an important part of the mire ecology. This is consistent with global high oxygen content and an in-land continental palaeogeographic position with seasonal precipitation. Stable isotopes of carbon indicate periods of high precipitation but also times of significant relative dryness. The palaeoclimatic conditions are likely to be both seasonal as well as longer term, possibly decadal to millennium in scale and would have occurred over the whole region, not just mire specific.

Discovery of Late Jurassic Sporopollen Assemblage from the Tamulangou Formation in the Hongqi Sag of the Hailar Basin, Inner Mongolia, China

Acta Geologica Sinica - English EditionVolume 94, Issue 5 p. 1718-1720 Research Advance Discovery of Late Jurassic Sporopollen Assemblage from the Tamulangou Formation in the Hongqi Sag of the Hailar Basin, Inner Mongolia, China Chuanbiao WAN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYunfei XUE, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYuewu SUN, Corresponding Author sunyuewu@jlu.edu.cn Key Laboratory for Evolution of Past Life and Environment in Northeast Asian (Jilin University), Ministry of Education, Changchun, 130026 ChinaCorresponding author. E-mail: sunyuewu@jlu.edu.cnSearch for more papers by this authorYanping HOU, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYudong JIN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorXin ZHANG, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorTi LI, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this author Chuanbiao WAN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYunfei XUE, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYuewu SUN, Corresponding Author sunyuewu@jlu.edu.cn Key Laboratory for Evolution of Past Life and Environment in Northeast Asian (Jilin University), Ministry of Education, Changchun, 130026 ChinaCorresponding author. E-mail: sunyuewu@jlu.edu.cnSearch for more papers by this authorYanping HOU, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYudong JIN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorXin ZHANG, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorTi LI, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this author First published: 08 October 2020 https://doi.org/10.1111/1755-6724.14590AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume94, Issue5October 2020Pages 1718-1720 RelatedInformation

Distribution Characteristics and Enrichment Model of Germanium in Coal: An Example from the Yimin Coalfield, Hailar Basin, China

As a rare and dispersed element, germanium cannot form independent ore deposits but can be enriched in coal and sphalerite. The target of this research is the Cretaceous Ge-rich coal seam of the Yimin Coalfield in the Hailar Basin, which hosts the third largest coal-hosted germanium ore deposit in China. Based on X-ray diffraction (XRD) analysis and inductively coupled plasma-mass spectrometry (ICP-MS), the ash, volatiles, total sulfur, and trace elements in the germanium-rich (Ge-rich) coal samples and partings were identified. The contents of these components, combined with the affinity of the coal samples, in terms of the concentration coefficient of the trace elements and the distribution pattern of the rare earth elements, were considered to discuss the occurrence of Ge in the coal, the potential germanium ore-forming environment and the metallogenic model. The Ge concentration of this coal ranges between 28.1 and 135.5 ppm. Laterally, the content of germanium obviously increases toward the direction of the Ge source, which is the Ge-rich granite near the coalfield margin. The concentration of Ge in the coal is inversely proportional to the content of ash and directly proportional to that of sulfur and volatiles, indicating that the germanium is combined with organic matter in an adsorbed state in the coal seams. The enrichments of As, Mo, CS, W, and Hg in the coal seams are positively correlated with the Ge content, which is possibly controlled by hydrothermal fluids. According to the lateral and vertical distributions of Ge-rich drilling data and the geological factors affecting the enrichment of germanium, a possible source-migration-concentration model of the germanium coal-hosted ore deposits in the Yimin coalfield was established.

Particle size effect on pore structure characteristics of lignite determined via low-temperature nitrogen adsorption

There is currently no uniform particle size of lignite for low-temperature nitrogen adsorption. Further, it is still unclear whether particle size has an effect on lignite pore structure. In this study, low-temperature nitrogen adsorption tests were used to study the pore structure of fresh lignite samples, using eight different particle size ranges from the Hailar Basin, northeastern China. The results show that lignite mainly contains macropores, and the proportion of macropore volume to total pore volume is 63.67–75.67%. The specific surface area and volume of macropores and mesopores decrease with decreasing particle size, and the reduction of macropores is more significant than that of mesopores. Optical and scanning electron microscopy observations showed that the predominant pore types in the lignite are plant tissue pores, intergranular pores, and microfractures, which occur in open pores. These differences in pore structures over the varied sizes are related to mechanical crushing. Specifically, decreases in coal particle size lead to a greater degree of collapse and destruction to open pores during progressive pulverization. Herein, the results show that the particle size of lignite is important to accurately determine its pore structure. To facilitate the comparison of the experimental results of different samples in future works, a mesh size of 1–2 is recommended as the optimal size range of lignite for low-temperature nitrogen adsorption studies.

Microstructure Investigation of Oil-Bearing Rhyolites: A Case Study from the Hailar Basin, NE China

Understanding the microstructure of rhyolites may greatly promote exploration efforts on rhyolitic hydrocarbon reservoirs; however, related studies are sparse. In this contribution, the microstructure and related porosity of oil-bearing rhyolitic lavas from the Hailar Basin (NE China) were investigated using a combination of optical microscopy, fluorescence image analysis, and scanning electron microscopy. The direct visual and quantitative analyses show that the rhyolites are heterogeneous and porous rocks and have complex microstructures. Phenocryst-rich rhyolitic lava, perlitic lava, and spherulitic rhyolite may be favorable targets for rhyolitic hydrocarbon exploration. For the phenocryst-rich rhyolitic lavas, embayment pores, cleavages, cavitational and shear fractures, and intracrystalline sieve pores are commonly observed in the phenocrysts; while flow-parallel laminar and micropores are ubiquitous in the groundmass. Perlitic lavas are characterized by the occurrence of numerous perlitic fractures which can also be produced in the glassy groundmass of other lavas. Spherulitic rhyolites mainly consist of small-sized (<1 mm) clustered or large-sized (>1 mm) isolated spherulites. Clustered spherulites are characterized by the development of interspherulite pores. Isolated spherulites contain numerous radiating micropores. Both types of spherulites may have water expulsion pores formed in the spherulite–glass border. The formation of the microstructure and related porosity of rhyolites is controlled by pre-, syn- (e.g., deuteric crystal dissolution, cavitation, ductile–brittle deformation, and high-T devitrification), and post-volcanic (e.g., hydration and low-T devitrification) processes. Although pores with diameters > 50 μm are often observed, small pores dominate in pore-size distribution. Small (<15 μm) and large (>300 μm) pores give the most volumetric contribution in most cases. Medium-sized pores with diameters ranging from ~150–300 μm are the least developed and contribute the least to the total volume. The results of this paper can be beneficial to further the understanding of the microstructure and pore system of rhyolites and may be applied to rhyolitic lava hydrocarbon reservoirs elsewhere.