Exploration In China Research Articles

The Fluid Evolution of Ancient Carbonate Reservoirs in Sichuan Basin and Its Implication for Shale Gas Exploration

Sichuan Basin is the only successful basin for shale gas exploration in China. In addition to the main shale in the Lower Silurian Longmaxi formation, the lower Cambrian Qiongzhusi shale is an important potential formation. However, it was once considered that shale gas is difficult to enrich because of its poor sealing conditions and hydrocarbon migration to adjacent reservoirs. With the increasing research on hydrocarbon generation and reservoir in shale of Qiongzhusi Formation in recent years, it has become an important exploration target in Sichuan Basin. The enrichment of oil and gas is closely related to fluid activities. Limited by the degree of exploration, there is little analysis of fluid activities in Qiongzhusi Formation, and there is little analysis of shale gas enrichment potential from the perspective of fluid. The hydrocarbon generated from Qiongzhusi shale in the rift could migrate laterally to the uplift area and form a reservoir in Dengying Formation. The fluid activities from source rock to reservoir are basically the same. Therefore, this paper reconstructed the history of hydrocarbon activities in Dengying reservoirs based on fluid inclusion analysis. Then the fluid activity process in Qiongzhusi shale was studied, and its enrichment conditions of shale gas was discussed. The results show that the hydrocarbon activities of Dengying Formation can be divided into three stages: 1) oil charging stage, 2) oil cracking gas generation stage and 3) gas reservoir adjustment stage. The first stage is under normal pressure, and the second and third stages developed overpressure with pressure coefficients of 1.3 and 1.2, respectively. High pressure coefficient is an important indicator of shale gas enrichment. Because the source rock of Qiongzhusi Formation has always been the main source rock of Dengying Formation, it can supply hydrocarbon to Dengying Formation only with overpressure in gas generation stage. Therefore, overpressure in the last two stages of gas generation indeed existed. As long as the sealing condition of shale itself is not particularly poor, shale gas “sweet points” would be formed. Therefore, the thick shale in Deyang-Anyue rift is the focus of shale gas exploration in Qiongzhusi Formation.

New Insights into the Pulang Porphyry Copper Deposit in Southwest China: Indication of Alteration Minerals Detected Using ASTER and WorldView-3 Data

The Pulang porphyry copper deposit (PCD), one of the main potential areas for copper resource exploration in China, exhibits typical porphyry alteration zoning. However, further investigation of the indicative significance of alteration minerals, additional insight into metallogenic characteristics, and prospecting guidelines continue to be challenging. In this study, ASTER and WorldView-3 data were used to map hydrothermal alteration minerals by employing band ratios, principal component analysis, and spectrum-area techniques; and subsequently, the indication significance of alteration minerals was studied in-depth. The following new insights into the metallogenic structure and spatial distribution of alteration zoning in Pulang PCD were obtained and verified. (1) A new NE trending normal fault, passing through the northeast of Pulang PCD, was discovered. (2) Two mineralization alteration centers, exhibiting alteration zoning characteristics of potassic-silicified, phyllic, and propylitic zones from the inside to the outside, were observed on both sides of the fault. (3) At the junction of the redivided potassic-silicification and phyllic zones, favorable prospecting potential areas were delineated. This study shows that the spectral/multi-sensor satellite data are valuable and cost-effective tools for the preliminary stages of porphyry copper exploration in inaccessible and remote areas around the world.

Arid climate disturbance and the development of salinized lacustrine oil shale in the Middle Jurassic Dameigou Formation, Qaidam Basin, northwestern China

The lacustrine Dameigou organic-rich shale of the northern Qaidam Basin is a particularly promising play for recent unconventional oil and gas exploration in China. Deposition was associated with arid intervals during the otherwise humid Middle Jurassic, but the depositional mechanism and organic matter enrichment processes are poorly understood. This study integrates high-resolution organic and inorganic geochemical proxies with detailed sedimentary observations for samples from the Chaiye (CY1) borehole, located in the Yuqia Depression, to investigate the depositional environment and development of the Dameigou shales. Four major lithofacies, including sandy mudstones, oil shale, organic-rich mudstone, and argillaceous mudstone, were identified through detailed microscopic observation and mineralogical analyses. Geochemical paleoclimate proxies (CIA, Fe/Mn and Mg/Ca) indicate that humidity fluctuations primarily drove the lithofacies variation. Other geochemical proxies, including terrigenous supply (Al2O3, Ti2O and regular sterane), lake salinity (Sr/Ba, S/TOC and Ga), redox conditions (V/Cr, U/Th and Pr/Ph), and primary productivity (Baxs, Pxs) indicate that climatic variability exerted a first-order control on the chemical evolution of the lake and the development of organic-rich shale in the Yuqia area. During arid intervals, fresh water supply through precipitation and river runoff weakened, leading to an increase in salinity and water column stratification. As a result, surface water became brackish and oxygen-rich, promoting growth of algae, but density stratification drove the bottom waters to anoxia, providing favorable conditions for organic matter preservation. Recycling of nutrients such as phosphorus under anoxic conditions further promoted eutrophication and high productivity in the surface water, which ultimately promoted the precipitation of carbonate minerals.

Practice of High-density 3D Seismic Exploration in Tight Oil Exploration in G Area of Central Sichuan

The Oil reservoir in Jurassic of Sichuan Basin is tight, thin, high heterogeneity, complex sand distribution and well-developed micro-fault etc., whose difference of buried depth is up to 2000m from south to north. The vertical and lateral resolution of conventional seismic exploration is too low to predict reservoir clearly, which restrains further development of close oil exploitation in central of Sichuan Basin. Lots of examples shows that high density acquisition is able to improve the description ability of seismic data, In G area of Sichuan Basin, a high-density, high-fold, small-cell, full-azimuthal 3D acquisition has been tested, which is the first mountainous high-density seismic exploration in China. In view of mass data and difficult geological target, a processing technique series including auto-first-break-picking, pre-stack noise suppression, robust surface consistent deconvolution, pre-stack time migration in OVT (Offset Vector Tile) field is applied to obtain high quality image. Analysis of multiple geological target results revealed that, the high-density data has fair higher signal-to-noise ratio, much wider bandwidth with more information, much better vertical and lateral resolution, which increased the identification of sand boundary, predication of thin reservoir, discrimination of micro-fault and fracture, recognition of sub geological features. It is well provided that high-density 3D seismic exploration has vast application future in close oil exploitation.

Micro/Nanopore Systems in Lacustrine Tight Oil Reservoirs, China.

A nanoscale pore throat system develops extensively in rocks of unconventional reservoirs serving as both source and reservoir rock. The nanoscale pores provide the main storage spaces, accounting for 70% to 80% of the total unconventional tight reservoirs in China. As one of most important unconventional petroleum accumulations, tight oil has accumulated in more than 20 lacustrine strata since the Permian in China. Three types of tight oil reservoirs were identified based on the lithology and provenance in the lacustrine basins, including terrigenous sandstone, endogenous carbonate rocks and mixed sedimentary rocks. The micro/nanopore structures of these tight rocks were investigated with the application of optical microscopy, scanning electron microscopy (SEM), mercury injection capillary pressure (MICP), gas adsorption (GA) and nuclear magnetic resonance (NMR). The results indicated that the pore systems were connected by nanoscale throats dominated the storage spaces of the lacustrine tight oil reservoirs, while there were obvious differences among these three tight rocks, including pore types, pore size and movable fluid distribution. (i) The terrigenous sandstones, which were represented by the Triassic Chang 7 tight sandstones in the Ordos Basin and Cretaceous Quantou tight sandstones in the Songliao Basin, were mainly arkoses, and their storage space was mainly composed of dissolution pores and intraclay mineral pores. Feldspar, rock fragments and carbonate cements were the majority of the dissolved components, and the diameter of dissolution pores ranged from 1 micron to 50 microns. Abundant intrakaolinite and illite/smectite mixed layers pores were developed, and the pore size was 10 nm to 500 nm. The MICP and GA data suggested that storage spaces were connected by throats with diameters of 10 nm˜300 nm. (ii) The endogenous carbonate rocks, which were represented by the Jurassic Da'anzhai limestones in the Sichuan Basin, were the tightest rocks with porosities of less than 5% and permeabilities of less than 0.01×10-3 μm². The calcite dissolution pores and fractures with diameters of 10 nm˜500 nm were the most important storage spaces. The majority of pore systems were connected by throats with diameters of 6 nm˜100 nm based on the MICP and GA data. (iii) The tight mixed sedimentary rocks, which were represented by the Permian Lucaogou Formation in the Junggar Basin, were complex in lithologic composition, and dolostones and dolomite sandstones were the most important exploration targets. The interdolomite pores were the dominant storage spaces, in which abundant illite/smectite mixed layers were filled, and the pore size ranged from 50 nm to 50 microns. The MICP and GA data showed that the storage space was dominated by throats with diameters of 10 nm˜200 nm, and their volumetric contributions could reach over 70%. These results could provide a reference for future tight oil research and exploration in China.

Exploration of China's Net Co2 Emissions Evolutionary Pathways by 2060 in the Context of Carbon Neutrality

Exploration of China's Net Co2 Emissions Evolutionary Pathways by 2060 in the Context of Carbon Neutrality

17세기 초 몽골을 통한 러시아의 중국 탐사가 갖는 세계사적 의미

본 논문의 목적은 17세기 초 동진 과정에서 러시아가 어떻게 몽골과 관계를 맺고, 중국에 대한 인식을 확대해 갔는지, 그리고 어떤 경로로 중국에 도착했는지 살펴봄으로써 러시아의 대중국 탐사가 세계사 특히 중앙유라시아 역사에서 갖는 의미를 찾는 것이다. 17세기 초 러시아는 베르골롭, 튜메네츠의 탐사를 시작으로 중국에 관심을 갖게 되었고, 마침내 1618년 페틀린 탐사대가 몽골을 경유해 명의 수도 북경에 도착했다. 페틀린이 여행을 통해 수집한 자료는 당대 지리학 수준에서 중요한 업적이었고, 그의 이름과 성과는 유럽에 널리 알려졌다. 러시아 연구자들은 탐사의 추진에서 영국인들의 역할을 강조하고, 또한 그 결과를 유럽이 진행한 북방항로 탐사의 결정판으로 보려는 경향이 있다. 그러나 러시아의 중국 발견이 유럽의 대항해 시대와 시기적으로 맞물려 있다고 해도, 그것은 유럽이 주도한 것이 아니라 중앙유라시아 국가들의 팽창으로 인한 결과였다. 17세기 초 러시아는 동쪽으로 팽창하는 과정에서 서시베리아에 근거지를 마련했다. 그리고 러시아뿐 아니라, 몽골도 목초지를 확대하기 위해 서시베리아 쪽으로 팽창하고 있었다. 바로 이런 과정에서 러시아와 몽골의 조우가 이루어졌고, 러시아인들은 몽골인들로부터 중국에 관한 정보를 접하게 되었고, 이는 러시아 제국최초의 중국 방문으로 이어졌다. 그러나 러시아인들이 직접 탐사를 통해 중국으로 가는 여행로를 찾아낸 것이 아니라, 몽골인들이 러시아인들을 중국까지 안전하게 데려다 준 것이었다. 러시아인들의 북경 방문이 만든 연결선은 향후 러시아와 몽골 그리고 중국을 잇는 선이었지, 결코 서유럽까지 연결되는 선은 아니었다. 이는 ‘13세기 세계체제’를 완성한 몽골제국이 쇠퇴한 이후 분열되고 고립되었던 중앙유라시아의 거대한 공간들이 새롭게 부상하는 정치체들을 중심으로 접촉하고 연결되기 시작하는 획기적 사건이었다.

Hydrocarbon generation-retention-expulsion mechanism and shale oil producibility of the permian lucaogou shale in the Junggar Basin as simulated by semi-open pyrolysis experiments

The shale of the Permian Lucaogou Formation in the Jimusar sag, Junggar Basin (abbreviated as the Lucaogou shale) is a typical lacustrine type-II source rock, and is among the most representative target zones for shale oil exploration in China. However, little attention has been paid to the dynamic changes of the shale decomposition; hydrocarbon generation, retention, and expulsion; physico-chemical properties; and producibility of shale oil at different stages of maturation in this shale. Semi-open pyrolysis experiments were performed on the Lucaogou shale; products including expelled gas, oil (expelled oil), bitumen (retained oil), and residual rock were obtained, and their quantities and chemical and physical compositions were comprehensively characterized. The results show that the density and molecular weight of the oil are lower than those of the bitumen, whereas the API gravity of the oil is higher than that of the bitumen, indicating the preferential expulsion of light hydrocarbons and short chains. The saturate, aromatic, resin and asphaltene (SARA) percentages of oils under the current semi-open pyrolysis experiments were similar to those of natural oils recovered from the Lucaogou Formation, suggesting that semi-open pyrolysis can achieve the same purpose as hydrous pyrolysis to simulate natural oil composition. The measured vitrinite reflectance (Ro) of the pyrolyzed shale was lower than the calculated Easy%Ro, which is in accord with findings from the Chang 7 shale (another typical lacustrine type-II shale in China) but distinct from previously reported type-III coals and marine type-II shales. Similar to the Chang 7 shale, the decomposition process of the Lucaogou shale did not follow the sequential reaction model described as kerogen → bitumen → oil or kerogen → NSOs → HCs. The generation of HCs (oil) and NSOs (bitumen) was independent and followed the “alternate pathway” mechanism under semi-open pyrolysis conditions. In the early oil window (Ro ˂ 1.0%), the hydrocarbon expulsion efficiency was relatively low, meaning that the shale simultaneously retained considerable amounts of oil during peak oil generation. The producibility of shale oil reached its maximum at the end of the oil window (1.0–1.2 %Ro), and this interval is considered the most suitable for fracturing technology.

Petrophysical properties of deep Longmaxi Formation shales in the southern Sichuan Basin, SW China

Abstract Deep shale layer in the Lower Silurian Longmaxi Formation, southern Sichuan Basin is the major replacement target of shale gas exploration in China. However, the prediction of “sweet-spots” in deep shale gas reservoirs lacks physical basis due to the short of systematic experimental research on the physical properties of the deep shale. Based on petrological, acoustic and hardness measurements, variation law and control factors of dynamic and static elastic properties of the deep shale samples are investigated. The study results show that the deep shale samples are similar to the middle-shallow shale in terms of mineral composition and pore type. Geochemical characteristics of organic-rich shale samples (TOC > 2%) indicate that these shale samples have a framework of microcrystalline quartz grains; the intergranular pores in these shale samples are between rigid quartz grains and have mechanical property of hard pore. The lean-organic shale samples (TOC

The exploration of China's National Park System Pilot Project: Taking Northeast China Tiger and Leopard National Park System Pilot Area as an example

In December 2016, Northeast China Tiger and Leopard National Park started the pilot work. It is the only pilot area that is directly managed by the central government. Northeast China Tiger and Leopard National Park System Pilot Area undertakes two major reform tasks. One is to explore the path to establish the national park system in China. Other is to improve the national natural resource asset management system. This paper comprehensively summarizes the progress and experiences of the Northeast China Tiger and Leopard National Park System Area. It has concluded that the Northeast China Tiger and Leopard National Park System Area has gained achievements in many aspect and the experiences has a possibility to be copied.

Eight-Year Medical Education Program: Retrospect and Prospect of the High-Level Medical Talent Training in China

Purpose: The 8-year medical education program (EYMEP) is China’s path to training high-level medical talents. In retrospect, this study systematically reviewed the developmental process of China’s EYMEP. The status quo and characteristics, and threats and challenges, were analyzed, along with the program’s prospects. Design/Approach/Methods: This study analyzed relevant textual materials and policy documents dating back to the time of hosting of China’s EYMEP, as well as conducted various specific interviews and field trips. Findings: The exploration of China’s high-level medical talent training has been conducted over a century. EYMEP can be divided into five periods: the Only Host Period, the Duplication Pilot Host Period, the Expansion Period, the Joint Exploration Period, and the In-Depth Promotion Period. Currently, there are 14 universities and institutes hosting the EYMEP approved by the Ministry of Education of the People’s Republic of China. However, they differ greatly in training ideas and goals, enrollment processes, and training phases. China’s EYMEP is faced with some external threats and internal challenges. In the future, China’s EYMEP should consider five aspects. Originality/Value: In the new era of the reform and development of China’s medical education, a systematic review of the development of EYMEP in China is of great significance to the promotion of high-level medical talent training in China. Meanwhile, the exploration course of China’s high-level medical talent training represented by the EYMEP may be an enlightenment for other countries, especially developing countries like China, in their training of high-level medical talents.

The exploration of China's National Park System Pilot Project: Taking Qilian Mountain National Park as an example

Qilian Mountain National Park became the pilot area of China National Park System Pilot Project in June 2017. This article provides a basic description of Qilian Mountain National Park System Pilot Area from the aspects of the important natural resources, key ecological functions, and important historical and cultural values. It explores, analyzes the construction path and effect of Qilian Mountain National Park System Pilot Area in management and operation, policy, ecological conversation and restoration, natural resources supervision and community. It has been concluded that the construction of Qilian Mountain National Park System Pilot Area has sound effect of ecological restoration, economic and social development and park governance capacity.

Carbonate reservoir evaluation and gas bearing prediction in Ordos Basin

In order to solve the problem that carbonate rocks are difficult to be explored due to their complex heterogeneity, the evaluation of carbonate reservoirs and the prediction of gas bearing are carried out. Firstly, taking the Sugeri gas field area in Ordos as an example, the address characteristics of the research area are introduced. Then the petrological characteristics and reservoir spatial characteristics (pore types and pore structures) of carbonate reservoirs are explored. In addition, the prediction and simulation method of carbonate reservoir gas bearing—amplitude variation with offset (AVO) forward modeling analysis method is discussed. Finally, the results of reservoir characteristics and prediction of reservoir gas bearing are analyzed. The results show that there is no effective reservoir development in Ma Wu32, Ma Wu33, and Ma Wu41b in the study area, and Ma Wu41a is the main effective reservoir development segment, followed by Ma Wu2 subsegment. For gas bearing prediction, there are a total of 10 favorable zones in Ma Wu segment, among which the predicted gas thickness is between 2 and 8 m. The results have good guiding significance for oil and gas exploration in China.

Several essential geological and geochemical issues regarding shale gas research in China

Recently, shale gas research and industrial production in China have been significantly developed, which has enriched the theory of natural gas geology in China and increased the supply of domestic natural gas production. In the future, shale gas will obtain great achievements among the developments of the natural gas industry in China. The following four geological and geochemical issues about the exploration and research of shale gas have great significance: (1) China has to break through the single economic shale gas formation. The United States found at least thirty sets of economic shale gas formations in 29 basins. To date, only one basin in China (Sichuan Basin) has found one set of economic shale gas formation (Wufeng-Longmaxi formations). (2) In regards to the interval RO value of the economic shale gas formations and segment RO value of the gas fields, the interval RO values are 3.31% for the economic shale gas formation in China. However, it is 4.1% for that in the USA. The segment RO values are 2.34% for the gas fields in China and 3.5% for that in the USA. So the values are small in China, but big in the USA. Several shale gas fields derived from sapropelic sources in the United States were found in the oil generation window with RO = 1.0%–1.3%. Therefore, shale gas exploration in China also needs to pay attention to this stage. At the same time, attention should be paid to the exploration of shale gas derived from humic sources. (3) When it comes to the continuous high-yield period of the gas field, the world's first commercially developed shale gas field (Barnett) shows a high-yield forecast of 10 × 109 m3 per year for about twenty years. The development of the shale gas field in China is still in the construction stage. (4) In terms of the role of fracture in shale gas preservation and development, the fault has a dual effect on the enrichment of shale gas. In the United States, tectonic in the shale gas basin is stable, and faults are few, while structures in China in the shale gas basin are active, and faults are developed. Therefore, faults have more harm than good to the shale gas in China, which caused the fragmentation of the continuously distributed Wufeng-Longmaxi formations, limiting the area of the gas field.

Stratigraphic Framework of the Cryogenian in China

AbstractThe Cryogenian is a critical period in the history of the Earth. It is marked by multiple extreme climate changes that caused alternating global glacial and interglacial intervals. These dramatically changed the sedimentary system, and metal ores and source rocks distributed widely during this period. Therefore, studying the Cryogenian stratigraphic framework and sedimentary basins is important to improve the stratigraphic resolution for metal mineral and hydrocarbon prospecting and exploration in China. This review paper firstly divides three tectonic‐stratigraphic regions in China in the Cryogenian, including the tectonic‐stratigraphic regions of Great South China, Xingmeng‐Tarim, and North China. Secondly, geochronologic data and geological records are combined to clearly depict the Cryogenian sedimentary sequence of continental blocks and micro‐continental blocks in different tectonic‐stratigraphic regions. The results were used to propose a new comparison scheme of stratigraphy for the Cryogenian in China. Finally, according to differences of sedimentary evolution and tectonic evolvement, sedimentary basins and their lithofacies paleogeography are identified and summarized, respectively.

Characteristics of low-rank coal reservoir and exploration potential in Junggar Basin: new frontier of low-rank CBM exploration in China

Low-rank coal reservoirs of Badaowan Formation and Xishanyao Formation are mainly developed in Junggar Basin. This paper discussed their features and coalbed methane (CBM) exploration potential based on geological survey, coal samples testing and mathematical fitting analysis. The pores are mainly small-micro- and large pores, and the porosity is 3.25–27.4% with an average of 9–10.51%; and macro-cracks and micro-fissures are well developed leading to a great variation of the permeability. The shallow coal reservoirs are mostly undersaturated, and the gas saturation tends to increase toward the deep coalbed. The J2x has a stronger methane adsorption and storage capacity than that of J1b and better physical properties, making CMB recovery easier. The coalbed reservoirs in middle-east of southern margin, eastern part and hinterland of Junggar Basin reach methane-rich to extremely methane-rich coalbeds and have strong ability to adsorb and store CBM. Coal seam gas shows generally, and the measured gas-bearing property is good. Low-rank CBM accounts for the majority of CBM resources in the basin. According to Langmuir volume, the gas provinces are classified into four types of blocks, i.e., CBM-poor (< 8 m3/t), CBM-bearing (8–15 m3/t), relatively CBM-rich (15–20 m3/t) and CBM-rich (> 20 m3/t). The relatively CBM-rich blocks cover block of well Qing 1 to Qi 8, Changji–Urumqi–Fukang area and slope belt of northwest margin to basin hinterland; while the CBM-rich blocks include most of eastern Junggar Basin. Since 2005, a series of special exploration and research of CBM have been carried out successively, and significant progress has been made in exploration of deep and shallow combination, conventional (gas) and unconventional (gas) combination. Recently shallow CBM exploration has achieved gas extraction at Dahuangshan coal mine, industrial gas flow wells in western Baiyanghe, and breakthrough of deep CBM exploration in Baijiahai area has been made, which confirmed the great development potential of low-rank CBM. The southern margin and the east of Junggar Basin have become the new frontier of low-rank CBM exploration in China.

Development history and prospect of remote sensing technology in coal geology of China

Coal remote sensing technology was founded in the period of coal resources survey after the founding of People’s Republic of China. Aerophoto Grammetry & Remote Sensing Bureau of China National Administration of Coal Geology was established, specializing in the application and promotion of coal remote sensing technology. With the rapid development of coal geological exploration in China, coal remote sensing technology has evolved from coal geology based survey to comprehensive survey that factors in resources, environment, ecology and so on. This paper summarizes the general situation, theories, development process, key research and future of remote sensing technology for coal mining in China. Spanning over 50 years, the history of China’s coal remote sensing technology can be divided into five stages: aero-geological mapping, coal remote sensing theory experimental research, application research and promotion, architecture planning and productionisation, “3S” technology integration and application. This paper expounds the main technical progress, application fields, major projects and major achievements in various historical periods, and points out that the coal remote sensing has entered a unified development stage of “Aviation, Aerospace and Ground”, with a focus on high-resolution remote sensing, hyperspectral remote sensing, radar remote sensing, “3S” technology integration and multi-means comprehensive exploration and evaluation. In the future, coal remote sensing technology will develop rapidly in data mass, technology integration, evaluation intelligence, integration application programming, system visualization, etc. Coal remote sensing technology has entered the industrial development from technology application.

The application of vibroseis in VSP logging in Sichuan and Chongqing area

In 1970s, vibroseis was introduced to do seismic exploration in China. After then, vibroseis equipment was researched and produced in China. The electro-control system of the force working on the ground, of vibroseis signal recognizing or installing, and of RT quality-controlling, which is based on the digital self-adapting method, enlarged the application of vibroseis not only the areas but also the quantity in seismic exploration. And then, vibroseis equipment became one of the important seismic equipment. As the producing of shale gas developed, and the traffic conditions improved, the vibroseis equipment and techniques began to work in VSP logging in Sichuan and Chongqing area, south-west of China. The effect of the vibroseis in VSP logging will be analyzed from the theory to the consistence and high S/N ratio of VSP data which be acquired by vibroseis.

Suggestions for China on establishing safety mechanisms for space nuclear power source applications

With the development of deep space exploration in China, the application of space nuclear power source (NPS) is becoming increasingly intense when solar energy cannot meet the mission requirements. Because of the particularity of its nuclear operation and use, the safety of the whole process has become a matter that must be paid attention to and guaranteed. Establishing a scientific and efficient safety mechanism is an important means to ensure the safety of the whole process. The Safety Framework for Nuclear Power Source Applications in Outer Space ( Safety Framework ) was developed jointly by United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) and International Atomic Energy Agency (IAEA), providing safety standards and technical guidelines for all countries. The Safety Framework is a consensus reached by the member states of COPUOS on the safety of space NPS, and it can be applied to all space NPS applications. Countries can flexibly adjust the guide according to their own actual situation to adapt to the organizational structure of their space NPS applications. According to the practical application needs of space NPS, the United States has developed and implemented its own domestic safety mechanisms. The comprehensive safety mechanism for space NPS applications in the United States is closely consistent with the requirements of the Safety Framework , and its relevant national laws are consistent with the three categories of guidance contained in the Safety Framework , namely, the guidance of government, management and technology. Even within the system of the federal law of the United States, stricter standards and assessment procedures for the safe use of space NPS have been adopted. The space NPS application program of the United States requires specific legal action measures and necessary procedures. If the relevant measures and procedures are not followed, the application of space NPS cannot be approved and started by the government departments. The guidelines of the three aspects of the Safety Framework have been strictly implemented in the comprehensive security mechanism of the United States. China’s space NPS application is still in its infancy. Although the relevant provisions of the Safety Framework have been tried to implement in China’s Chang’E-3 and -4 missions, there is still no long-term national space NPS safety mechanism. Based on the Safety Framework and the experience of the United States, combined with the safety practice of space NPS in China, this article puts forward some suggestions for further improving the comprehensive safety management mechanism in China: (1) Establish or improve the national laws and regulations system to ensure that all responsibilities and procedures for the safety of space NPS applications are effectively fulfilled; (2) establish or improve the safety mechanism of space NPS application at the government level, so as to ensure the whole elements and process of space NPS application safety; (3) strengthen the safety technology reserve of space NPS application, so that relevant departments have and maintain the technical capacity of safety application. In the context of the drafting of China’s national space law, the decision makers of relevant departments of space NPS application should draw on the international rules such as the Safety Framework and the safety management mechanism of space NPS in major space countries, and formulate the safety management mechanism applicable to China’s space NPS application, which will be conducive to the early realization of China’s space NPS application safety system and meticulous management to ensure the smooth implementation of the space exploration mission.

Impact of the Paleoclimate, Paleoenvironment, and Algae Bloom: Organic Matter Accumulation in the Lacustrine Lucaogou Formation of Jimsar Sag, Junggar Basin, NW China

Shale oil exploration has been a key area of onshore oil and gas exploration in China in recent years. In this study, organic geochemistry and element geochemistry are united to study the shale oil and source rock in the Lucaogou formation of Jimusar sag, in order to reveal the paleoclimate, paleoenvironment, source of organic matter, and factors affecting organic matter accumulation and shale oil generation. The shale oil in the study area is mainly accumulated in two strata with good reservoir properties and oiliness, known as the upper sweet spot and lower sweet spot. Indexes of biomarkers and sensitive elements revealed the warm and semi-arid paleoclimate during Lucaogou formation, and the water column was brackish to salty. Water stratification caused a suboxic to anoxic environment in the deep-water column and coincided with the anoxic photic zone phenomenon. Compared with the lower sweet spot, the more humid climate, deeper and fresher water, and stronger water stratification characterize the upper sweet spot during sedimentation. This made the photic zone with freshwater more suitable for the reproduction of algae in the upper sweet spot. Meanwhile, the organic matter was well-preserved in the anoxic zone. Volcanic ash caused algae bloom, which promoted primary productivity and ensured the supply of organic matter. The composition and distribution pattern of biomarkers prove that phytoplankton is the most important source of organic matter in the study area and the contribution of higher plants is insignificant. The relationship between parameters of paleoproductivity and the redox condition versus total organic carbon (TOC) suggests that compared with the preservation conditions, the input of organic carbon is the most important controlling factor of organic matter accumulation in the study area.