GEOFLUIDS 是一份经过同行评审的开放获取期刊，为与流体在地壳的矿物学、化学和结构演化中的作用相关的原创研究和评论提供了一个论坛。其明确目标是在开展地流体研究的各个子学科范围内传播思想。为此，鼓励作者强调其研究的跨学科相关性和国际影响。还鼓励作者尽可能让其他子学科的读者能够访问他们的工作。GEOFLUIDS 强调整个地壳中地下流体的化学、微生物和物理方面。 GEOFLUIDS 涵盖地下水、陆地或海底地热流体、盆地盐水、石油、变质水或岩浆流体的研究。

GEOFLUIDS is a peer-reviewed open-access journal that provides a forum for original research and reviews related to the role of fluids in the mineralogy, chemistry, and structural evolution of the Earth's crust. Its explicit aim is to disseminate ideas across various sub-disciplines involved in geofluid research. Authors are encouraged to highlight the interdisciplinary relevance and international impact of their work, and to present their findings in a manner accessible to readers from other sub-disciplines. GEOFLUIDS emphasizes the chemical, microbial, and physical aspects of subsurface fluids throughout the crust, covering studies on groundwater, terrestrial or submarine geothermal fluids, basin brines, petroleum, metamorphic waters, and magmatic fluids.

GEOFLUIDS 是一本经过同行评审的开放获取期刊，专注于流体在地壳中的矿物学、化学和结构演化方面的原创研究和评论。期刊的目标是传播与地流体研究相关的各个子学科的思想，鼓励作者强调其研究的跨学科相关性和国际影响力。同时，作者也被鼓励以便于其他子学科的读者理解的方式呈现他们的工作。GEOFLUIDS 强调地下流体在整个地壳中的化学、微生物和物理特性，涵盖地下水、陆地或海底地热流体、盆地盐水、石油、变质水和岩浆流体等研究。

Geofluids

AVO inversion is a seismic exploration methodology used to predict the earth’s elastic parameters and thus rocks and fluid properties. It is built up on elastic theory and does not consider the seismic dispersion in real strata. Recent experiments and theory of rock physics have shown that in hydrocarbon-bearing rocks, especially in gas-bearing ones, the change of seismic velocity with frequency may be pretty remarkable for fluid flow in pore space. Some scholars proposed methods about seismic dispersion, such as frequency-dependent AVO inversion, to forecast oil and gas reservoirs underground. In this paper, we demonstrate an improved scheme of frequency-dependent AVO inversion, which is based on conventional Smith-Gidlow’s AVO equation, to extract seismic dispersion and predict the hydrocarbon underground. A simple model with gas-bearing reservoir is devised to validate the inversion scheme, and further analysis indicates that our scheme is more accurate and reasonable than the previous scheme. Our new scheme applied to the tight gas reservoirs in Fenggu area of western Sichuan depression of China finds that regions with high dispersion gradients correlate well with regions with prolific gas. Analysis and case studies show that our scheme of frequency-dependent AVO inversion is an efficient approach to predict gas reservoirs underground.

Jiong Liu

Jun-rui Ning

Xi-wu Liu

Chun-yuan Liu

Tian-sheng Chen

An Improved Scheme of Frequency-Dependent AVO Inversion Method and Its Application for Tight Gas Reservoirs

频率依赖AVO反演方法的改进方案及其在致密气藏中的应用

Pore pressure and fluid flow during the deformational history of geologic structures are directly influenced by tectonic deformation events. In this contribution, 2D plane strain finite element analysis is used to study the influence of different permeability distributions on the pore pressure field and associated flow regimes during the evolution of visco-elastic single-layer buckle folds. The buckling-induced fluid flow regimes indicate that flow directions and, to a lesser degree, their magnitudes vary significantly throughout the deformation and as a function of the stratigraphic permeability distribution. The modelling results suggest that the volumetric strain and the permeability distribution significantly affect the resulting flow regime at different stages of fold development. For homogeneous permeability models (k > 10 21 m), low strain results in a mostly pervasive fluid flow regime and is in agreement with previous studies. For larger strain conditions, fluid focusing occurs in the buckling layer towards the top of the fold hinge. For low permeabilities (<10 21 m), local focused flow regimes inside the buckling layer emerge throughout the deformation history. For models featuring a low-permeability layer embedded in a high-permeability matrix or sandwiched between high-permeability layers, focused flow regimes inside the folded layer result throughout the deformation history, but with significant differences in the flow vectors of the surrounding layers. Fluid flow vectors induced by the fold can result in different, even reversed, directions depending on the amount of strain. In summary, fluid flow regimes during single-layer buckling can change from pervasive to focused and fluid flow vectors can be opposite at different strain levels, that is the flow vectors change significantly through time. Thus, a complete understanding of fluid flow regimes associated with singlelayer buckle folds requires consideration of the complete deformation history of the fold.

A. Eckert

X. Liu

P. Connolly

Pore pressure evolution and fluid flow during visco-elastic single-layer buckle folding

粘弹性单层褶皱变形过程中的孔隙压力演变与流体流动

The hypothesis that basinal brines inherited their major ion chemistries and elevated salinities from evaporated paleoseawaters is tested by comparing the compositions of basinal brines in Silurian (Michigan basin, Illinois basin, Appalachian basin in eastern Ohio) and Jurassic/Cretaceous (Central Mississippi Salt Dome basin, Arkansas shelf, and south‐central Texas) host rocks, when the world oceans were ‘CaCl2seas’, with those from Permian and Pennsylvanian rocks (Palo Duro basin, Central Basin Platform, and Delaware basin, Texas and New Mexico) when the world oceans were ‘MgSO4seas’. Basinal brines examined are assumed to have originally formed from evaporation of the same seawaters that produced major evaporites. Sulfate, Mg and K levels in basinal brines are below the concentrations expected from evaporation of seawater of any type, which emphasizes the importance of diagenetic mineral–brine interactions in controlling basinal brine chemistry. There are no major differences in SO4, Mg and K concentrations between basinal brines hosted by rocks originally formed during ages when the world oceans were MgSO4seas versus CaCl2seas. Basinal brines in Pennsylvanian–Permian rocks are compositionally distinct (relatively high Na and low Ca) from basinal brines in Silurian, Jurassic and Cretaceous host rocks, which may reflect original differences in seawater chemistry. Basinal brines enriched in Ca and depleted in Na relative to evaporated seawater of any type have traditionally been interpreted to form by albitization of plagioclase feldspar. A new explanation for Ca enrichment and Na depletion of basinal brines is the mixing of evaporated CaCl2‐type seawater with more dilute water. Some basinal brines are similar in major ion composition to evaporated seawater of a particular age, for example basinal brines in the Cretaceous Edwards Group carbonates, Texas, where dolomitization is the only reaction required to convert evaporated Mesozoic CaCl2seawater into Edwards Group brine.

T. K. LOWENSTEIN

M. N. TIMOFEEFF

Secular variations in seawater chemistry as a control on the chemistry of basinal brines: test of the hypothesis

盆地卤水化学受海水化学长期变化的控制：假设检验

Formation water is produced during gas well production, which can seriously affect gas well productivity, especially in deep and ultradeep tight sandstone gas reservoirs. In this paper, we have studied the formation water production and geochemical properties of the ultradeep tight sandstone gas reservoir in the Cretaceous Bashijiqike Formation of the DK gas field in the Kuqa Depression. The results indicate that the formation water can be classified as condensate water, gas-water transition zone water, mixed water, and isolated formation water, all of which are acidic and of CaCl2 type, with increasing salinity or chloride ion content. Sodium/chloride ratio (ρNa+/ρCl-), metamorphic coefficient (ρ(Cl--Na+)/ρ(Mg2+)), desulfurization coefficient (100×ρSO42−/ρCl−), and trace elements concentration parameters show that the formation water was formed in a closed and reductive environment and experienced strong water-rock interaction. The formation water may have been influenced by early seawater, but it is not significant and is more likely to have been influenced by water seepage from the overlying gypsum strata. The Sr, H, and O isotopes reveal that the different types of formation water have good homology and are not affected by atmospheric precipitation, which is propitious to the preservation of natural gas.

Xiaobo Guo

Libin Zhao

Wei Han

Longfei Zhou

Zhilong Huang

Xiongwei Sun

Xuejun Yang

Tonghui Zhang

Chenglin Zhang

Geochemistry of Formation Water and Implications for Ultradeep Tight Sandstone of DK Gas Field in Kuqa Depression

库车坳陷DK气田超深层致密砂岩地层水地球化学特征及意义

Calcite veins in Paleoproterozoic granitoids on the Baltic Shield are the focus of this study. These veins are distinguished by their monomineralic character, unusual thickness and closeness to Neoproterozoic dolerite dykes and therefore have drawn attention. The aim of this study was to define the source of these veins and to unravel their isotopic and chemical nature by carrying out fine‐scale studies. Seven calcite veins covering a depth interval of 50–420 m below the ground surface and composed of breccias or crack‐sealed fillings typically expressing syntaxial growth were sampled and analysed for a variety of physicochemical variables: homogenization temperature (Th) and salinity of fluid inclusions, and stable isotopes (87Sr/86Sr,13C/12C,18O/16O), trace‐element concentrations (Fe, Mn, Mg, Sr, rare earth elements) and cathodoluminescence (CL) of the solid phase. The fluid‐inclusion data show that the calcites were precipitated mainly from relatively low‐temperature (Th= 73–106°C) brines (13.4–24.5 wt.% CaCl2), and the87Sr/86Sr is more radiogenic than expected for Rb‐poor minerals precipitated from Neoproterozoic fluids. These features, together with the distribution of δ13C and δ18O values, provide evidence that the calcite veins are not genetic with the nearby Neoproterozoic dolerite dykes, but are of Paleozoic age and were precipitated from warm brines expressing a rather large variability in salinity. Whereas the isotopic and chemical variables express rather constant average values among the individual veins, they vary considerably on fine‐scale across individual veins. This has implications for understanding processes causing calcite‐rich veins to form and capture trace metals in crystalline bedrock settings.

O. M. Maskenskaya

H. Drake

C. Broman

J. K. Hogmalm

G. Czuppon

M. E. Åström

Source and character of syntaxial hydrothermal calcite veins in Paleoproterozoic crystalline rocks revealed by fine‐scale investigations

通过精细尺度研究揭示的古元古代结晶岩中顺层热液方解石脉的来源与特征

Improving the oil production from nonmain oil layers is crucial for the complex fault block oilfields during the late stage of high water cut development to ensure stable production and capacity expansion. However, the developing characterization of the nonmain layers and their remaining oil distribution is still inadequate. Developing an efficient mode of development remains a challenge. This paper presents a detailed characterization of the sedimentary microfacies and architecture of a nonmain reservoir based on core and logging data analysis. A flexible injection-production development strategy model was designed and applied in the Hetan oilfield, located in the southeast of Zhanhua Depression of Bohai Bay Basin as an example. The results show that the nonmain oil layer of the Hetan oilfield is composed of estuary bar microfacies sand bodies. Deposits of various shapes are formed on the side or in front of the main body of the estuary dam, which constitutes the nonmain oil reservoir. The lithology is fine, the sand body thickness is small, and the plane heterogeneity is strong. The distribution is banded, potato-shaped, and fragmented. The nonmain oil layer has a small oil-bearing area of 0.1-1.0 km2 and a high oil saturation of over 58%. The Hetan oilfield has a significant amount of remaining oil enrichment and considerable potential for production digging. To optimize production, a flexible injection and production adjustment scheme is proposed, which includes designing multitarget horizontal wells and utilizing various methods such as optimizing well spacing, coupled injection, and cycle injection. Field tests conducted in the area have shown an increase in the recovery factor of nonmain oil layers from 16.7% to 28.5%. This indicates that identifying and characterizing nonmain oil layers through detailed analysis of sedimentary microfacies and reservoir architecture is useful in the late-stage development of complex fault block reservoirs to maintain sustainable and efficient oilfield development.

Lei Xu

Xiutian Yao

Sen Yan

Zhang Wen

Jimei Xue

Fine Characterization of Nonmain Oil Layer Distributions in Complex Fault Block Oilfield and Its Development Model

复杂断块油田非主力油层分布精细表征及其开发模式

The management of rock mass deformation in high-stress roadways is a pivotal aspect of deep geotechnical engineering. Given the fruitful outcomes of research in rock mechanics regarding traditional confining pressure control methods, scholars have increasingly turned their attention to exploring pressure-relieving techniques, including borehole pressure relief and blasting pressure relief. However, there is limited research on pressure relief methods for deep-buried hard rock tunnels. This article commences with an overview of pressure relief in the roadway and conducts a detailed study on the parameters and methods of pressure relief in the roadway. To address safety and mining efficiency challenges, such as severe deformation leading to support failures, this study conducted a parameter analysis using the Sanshandao Gold Mine as a case study. Based on existing support methods, a strategy for arranging pressure relief roadways at varying distances from the main roadway is proposed, significantly enhancing the stress environment there. Numerical simulation software was employed to model two scenarios: (1) excavating the pressure relief roadway, main roadway, and maintenance roadway simultaneously and (2) first excavating the pressure relief roadway, followed by the main roadway and the maintenance roadway simultaneously. Simulation results indicated that the first pressure relief approach outperforms the second. The optimal position for both pressure relief roadways is 15 m from the main roadway, resulting in maximum deformation of the main roadway within 100 mm. These findings align with on-site stress monitoring data and satisfy safety production criteria. The research offers a theoretical foundation for similar pressure relief techniques in deeply buried, high-stress roadways.

MingWei Jiang

YuYun Fan

WeiWei Su

Jincheng Wang

Ming Lan

Qibin Lin

Optimization of Support and Relief Parameters for Deep-Buried Metal Mine Roadways

深埋金属矿山巷道支护与卸压参数优化

Gas flaring (GasF) is an important aspect of the combustion mechanisms in the burning of related, undesirable, or surplus fluids (gases in particular) that are released during the ordinary or unexpected overpressuring process in several industrial activities, specifically in the petroleum resource (PTR) industries. It is also one of the major sources of greenhouse gas emissions which cause climate change (CMC). In addition to the generation of noise and heat, it makes substantial adjacent areas uninhabitable and, hence, causes detrimental consequences to the entire ecosystem as well as waste energy and results in economic losses. Reducing GasF is a critical issue due to its ensuing complications; consequently, there is a tenacious need to measure GasF via the study of its composition, distribution, and capacity, as well as the utilization of appropriate GasF recovery/removal procedures. The present review study will, thus, attempt to assess the impacts of GasF on the environment vis-à-vis the possible nexus between GasF/CMC using the perspective of the Niger Delta region of Nigeria which is rich in PTR, with relevant information drawn from existing publications. The roles of government, policymakers, and relevant stakeholders as well as suggestions and recommendations that will assist in the extenuation approaches and technologies of the influence of GasF on the environment are also discussed.

Kingsley Eghonghon Ukhurebor

Uyiosa Osagie Aigbe

Robert Birundu Onyancha

Hussain Athar

Benedict Okundaye

Paul Atagamen Aidonojie

Benita Ebindu Siloko

Ismail Hossain

Heri Septya Kusuma

Handoko Darmokoesoemo

Environmental Influence of Gas Flaring: Perspective from the Niger Delta Region of Nigeria

天然气放空的环境影响：尼日尔三角洲地区的视角

Gas migration incidents, particularly stream contamination cases, have been rarely investigated and gone through the peer review process, with the exception of three sites in northeast Pennsylvania (Dimock and two Sugar Runs in Lycoming and Bradford counties, respectively) where air emission surveys, dissolved methane measurements, and structural (hydro)geologic interpretations have been used to demonstrate potential environmental impacts due to shale gas operations. In addition to reviewing previously published work from these three sites, we report and analyze unpublished new data trying to determine if a direct relationship between methane migration, stream contamination, and air emissions exists at those sites. Our analysis indicates that subsurface methane migration, stream methane contamination, and air emissions might not be all present or detectable at a faulty/leaky shale gas well. Which of these signs of contamination, if any, exist is largely controlled by the local (hydro)geologic conditions. In each case, the most likely migration pathway was from gas charged zones up well annular spaces to confined permeable formations, then laterally to a direct discharge or by vertically controlled joints to streams, water wells, and the atmosphere. The confining units act as barriers to the buoyant movement of stray gases, allowing subsurface travel of gas for 1–4 km from a leaky gas well. The knowledge we learn from these three sites can guide the future investigations of methane contamination cases in other regions.

Patrick A. Hammond

Tao Wen

Josh Woda

David Oakley

Pathways and Environmental Impacts of Methane Migration: Case Studies in the Marcellus Shale, USA

甲烷迁移的路径与环境影响：美国马塞勒斯页岩的案例研究

The red-bed soft rocks in South China have obvious creep characteristics and are prone to engineering geological disasters such as landslide and foundation settlement under the action of rainfall, groundwater, and load. In order to reveal its creep characteristics and mechanism under complex conditions, a step-loading creep test was carried out under chemical-stress-seepage coupling, and the energy evolution law of the whole creep process was analyzed based on linear energy storage and energy dissipation theory. The results also show that the acid chemical solution has the greatest influence on the triaxial strength and creep strength, and the creep damage and energy evolution of red-bed soft rock are universal. The creep damage and total strain increase with the increase of acidity, the decrease of confining pressure, and the increase of seepage pressure. The evolution law of creep damage shows the characteristics of slow-acceleration-rapid growth, and with the increase of load level, it has obvious transfer and accumulation. After entering the constant velocity creep stage, the damage rate begins to accelerate. The proportion of instantaneous strain and creep strain in the total strain increment is about 50%, and confining pressure has little influence on their respective proportions. The instantaneous strain is more sensitive to the acidity of the chemical solution, and the proportion of creep strain increases gradually with the increase of seepage pressure. The relationship between elastic energy density and total energy density is linear. The elastic energy density and dissipated energy density in the loading stage and creep stage all increase nonlinearly with loading time. The density of dissipated energy in the creep phase is lower than that in the loading phase, but the opposite is true in the higher stress phase, and the law of energy dissipation can explain the hardening damage effect in the creep process of soft rock samples. The research results provide a new perspective for us to reveal the mechanical properties and failure mechanism of red-bed soft rocks and provide an important theoretical basis for predicting and evaluating the creep instability and long-term stability of such rocks.

Shuguang Zhang

Fanyao Peng

Yingbo Li

Zhifeng Liu

Wenbo Liu

Creep Energy Evolution of Red-Bed Soft Rocks in South China under Chemical-Stress-Seepage Coupling

华南红层软岩在化学-应力-渗流耦合作用下的蠕变能量演化

Abbreviation
Journal Impact	1.08
Quartiles(Global)	GEOLOGY(Q2)

ISSN	1468-8115, 1468-8123
h-index	68

Publication Information	Publisher: Hindawi Limited，Publishing cycle: Quarterly，Journal Type: journal，Open Access Journals: Yes
Basic data	Year of publication: 2001，Proportion of original research papers: 98.40%，Self Citation Rate:8.30%， Gold OA Rate: 99.70%
Journal Fees	$2060Details
Average review cycle	期刊官网数据：平均Submission to final decision: 62 days; Acceptance to publication: 25 days网友分享经验：>12周，或约稿
Average recruitment ratio	网友分享经验：57%

Geofluids

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