Potential evaluation of saline aquifers for the geological storage of carbon dioxide: A case study of saline aquifers in the Qian-5 member in northeastern Ordos Basin

The well-developed coal electricity generation and coal chemical industries have led to huge carbon dioxide(CO_(2))emissions in the northeastern Ordos Basin.The geological storage of CO_(2) in saline aquifers is an effective backup way to achieve carbon neutrality.In this case,the potential of saline aquifers for CO_(2) storage serves as a critical basis for subsequent geological storage project.This study calculated the technical control capacities of CO_(2) of the saline aquifers in the fifth member of the Shiqianfeng Formation(the Qian-5 member)based on the statistical analysis of the logging and the drilling and core data from more than 200 wells in the northeastern Ordos Basin,as well as the sedimentary facies,formation lithology,and saline aquifer development patterns of the Qian-5 member.The results show that(1)the reservoirs of saline aquifers in the Qian-5 member,which comprise distributary channel sand bodies of deltaic plains,feature low porosities and permeabilities;(2)The study area hosts three NNE-directed saline aquifer zones,where saline aquifers generally have a single-layer thickness of 3‒8 m and a cumulative thickness of 8‒24 m;(3)The saline aquifers of the Qian-5 member have a total technical control capacity of CO_(2) of 119.25×10^(6) t.With the largest scale and the highest technical control capacity(accounting for 61%of the total technical control capacity),the Jinjie-Yulin saline aquifer zone is an important prospect area for the geological storage of CO_(2) in the saline aquifers of the Qian-5 member in the study area.

Geological characteristics and models of fault-foldfracture body in deep tight sandstone of the second member of Upper Triassic Xujiahe Formation in Xinchang structural belt of Sichuan Basin,SW China

In the second member of the Upper Triassic Xujiahe Formation(T_(3)x_(2))in the Xinchang area,western Sichuan Basin,only a low percent of reserves has been recovered,and the geological model of gas reservoir sweet spot remains unclear.Based on a large number of core,field outcrop,test and logging-seismic data,the T_(3)x_(2) gas reservoir in the Xinchang area is examined.The concept of fault-fold-fracture body(FFFB)is proposed,and its types are recognized.The main factors controlling fracture development are identified,and the geological models of FFFB are established.FFFB refers to faults,folds and associated fractures reservoirs.According to the characteristics and genesis,FFFBs can be divided into three types:fault-fracture body,fold-fracture body,and fault-fold body.In the hanging wall of the fault,the closer to the fault,the more developed the effective fractures;the greater the fold amplitude and the closer to the fold hinge plane,the more developed the effective fractures.Two types of geological models of FFFB are established:fault-fold fracture,and matrix storage and permeability.The former can be divided into two subtypes:network fracture,and single structural fracture,and the later can be divided into three subtypes:bedding fracture,low permeability pore,and extremely low permeability pore.The process for evaluating favorable FFFB zones was formed to define favorable development targets and support the well deployment for purpose of high production.The study results provide a reference for the exploration and development of deep tight sandstone oil and gas reservoirs in China.

“Extreme utilization” theory and practice in gas storages with complex geological conditions

Based on more than 20-year operation of gas storages with complex geological conditions and a series of research findings, the pressure-bearing dynamics mechanism of geological body is revealed. With the discovery of gas-water flowing law of multi-cycle relative permeability hysteresis and differential utilization in zones, the extreme utilization theory targeting at the maximum amount of stored gas, maximum injection-production capacity and maximum efficiency in space utilization is proposed to support the three-in-one evaluation method of the maximum pressure-bearing capacity of geological body, maximum well production capacity and maximum peak shaving capacity of storage space. This study realizes the full potential of gas storage(storage capacity) at maximum pressure, maximum formation-wellbore coordinate production, optimum well spacing density match with finite-time unsteady flow, and peaking shaving capacity at minimum pressure, achieving perfect balance between security and capacity. Operation in gas storages, such as Hutubi in Xinjiang, Xiangguosi in Xinan, and Shuang6 in Liaohe, proves that extreme utilization theory has promoted high quality development of gas storages in China.

Quantitative analysis of geological ore-controlling factors and stereoscopic quantitative prediction of concealed ore bodies

To address the issues for assessing and prospecting the replaceable resource of crisis mines, a geological ore-controlling field model and a mineralization distribution field model were proposed from the viewpoint of field analysis. By dint of solving the field models through transferring the continuous models into the discrete ones, the relationship between the geological ore-controlling effect field and the mineralization distribution field was analyzed, and the quantitative and located parameters were extracted for describing the geological factors controlling mineralization enrichment. The method was applied to the 3-dimensional localization and quantitative prediction for concealed ore bodies in the depths and margins of the Daehang mine in Guangxi, China, and the 3-dimensional distribution models of mineralization indexes and ore-controlling factors such as magmatic rocks, strata, faults, lithology and folds were built. With the methods of statistical analysis and the non-linear programming, the quantitative index set of the geological ore-controlling factors was obtained. In addition, the stereoscopic located and quantitative prediction models were set up by exploring the relationship between the mineralization indexes and the geological ore-controlling factors. So far, some concealed ore bodies with the resource volume of a medium-sized mineral deposit are found in the deep parts of the Dachang Mine by means of the deep prospecting drills following the prediction results, from which the effectiveness of the predication models and results is proved.

Active source seismic imaging on near-surface granite body:case study of siting a geological disposal repository for high-level radioactive nuclear waste

In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small town named Tamusu,Western China.The study area is with complex surface conditions,thus the seismic exploration encountered a variettraveltimey of technical difculties such as crossing obstacles,de-noising harmful scattered waves,and building complex near-surface velocity models.In order to address those problems,techniques including cross-obstacle seismic geometry design,angle-domain harmful scattered noise removal,and an acoustic wave equation-based inversion method jointly utilizing both the and waveform of frst arrival waves were adopted.The fnal seismic images clearly exhibit the target rock’s unconformable contact boundary and its top interface beneath the sedimentary and weathered layers.On this basis,it could be confrmed that the target rock is not thin or has been transported by geological process from somewhere else,but a native and massive rock.There are a few small size fractures whose space distribution could be revealed by seismic images within the rock.The fractures should be kept away.Based on current research,it could be considered that active source seismic exploration is demanded during the sitting process of the geological disposal repository for nuclear waste.The seismic acquisition and processing techniques proposed in the present paper would ofer a good reference value for similar researches in the future.

An Expression for Gravity Generated by an Anomalous Geological Body and Its Application in Bathymetry Inversion

The gravity anomaly and vertical gravity gradient due to anomalous geological bodies are mainly computed by numerical methods,so it is difficult and time-consuming to use the gravity-geological method to invert seafloor topography.This paper addresses this issue by deriving an expression for gravity generated by a cylinder based on a series expansion.The choice of number for terms in the series is estimated by comparing with the numerical method,especially when the depth H=4000m,the accuracy of 1 mGal(1 Gal=10^(-2)m/s^(2))can be achieved when the series are 9.The expressions can be used to establish the relationships between the shape of an anomalous body and the generated vertical gravity and vertical gravity gradient,respectively.Finally,the potential applications of the expressions in inverting seafloor topography are illustrated by synthetic examples.

Cybernetics of Engineering Geological Bodies

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Highlighting display of geologic bodies based on directivity filtering

To make a geologic body more outstanding, it is necessary to preserve edges when filtering. For this reason, a filtering method based on anisotropic diffusion is introduced. The key point of this method is that diffusion filtering will be made along the edge while diffusion is forbidden in the direction perpendicular to the edge, so the filtering has directionality. When doing anisotropic diffusion filtering, parameters like diffusion coefficient and threshold have great impacts on the results, so the anisotropic diffusion model parameters are discussed, the diffusion coefficient equation is introduced, and the diffusion threshold selection criterion is derived and analyzed. In addition, this method was used with the diffusion coefficient equation＇s proper diffusion threshold to highlight the tidal channel geobodies in the XX area, sand body in the YY area, and faults in the ZZ area. The good delineation results prove that the diffusion threshold selection criterion introduced in this paper is reasonable.

Study on the scales of heterogeneous geologic bodies in random media

In order to study the scale characteristics of heterogeneities in complex media, a random medium is constructed using a statistical method and by changing model parameters （autocorrelation lengths a and b）, the scales of heterogeneous geologic bodies in the horizontal and the vertical Cartesian directions may be varied in the medium. The autocorrelation lengths a and b represent the mean scale of heterogeneous geologic bodies in the horizontal and vertical Cartesian directions in the randQm medium, respectively. Based on this model, the relationship between model autocorrelation lengths and heterogeneous geologic body scales is studied by horizontal velocity variation and standard deviation. The horizontal velocity variation research shows that velocities are in random perturbation. The heterogeneous geologic body scale increases with increasing autocorrelation length. The recursion equation for the relationship between autocorrelation lengths and heterogeneous geologic body scales is determined from the velocity standard deviation research and the actual heterogeneous geologic body scale magnitude can be estimated by the equation.

Study upon Modeling and Visualization of 3D Geologic Body Based on Generalized Tri-Prism

According to the characteristics of bore data,a model of 3D geologic body with generalized tri-prism as the primitive modeling element is constructed while the modeling process and key algorithms of modeling are presented here in detail.Using this method,the original bore data go through Delaunay triangulation to generate irregular triangular network on the surface,and then links stratum segments on the adjoining bores in session to form tri-prisms which would be pinched out.Finally stratified 3D geologic body model is built by an iterated search which searches for consecutive layer of the same property.The result shows that this method can effectively simulate stratified stratum modeling.

Research and Application of In-seam Seismic Survey Technology for Disaster-causing Potential Geology Anomalous Body in Coal Seam

In order to effectively detect potential geology anomalous bodies in coal bearing formation,such as coal seam thickness variation,small faults,goafs and collapse columns,and provide scientific guidance for safe and efficient mining,the SUMMIT-II EX explosion-proof seismic slot wave instrument,produced by German DMT Company,was used to detect the underground channel wave with the help of transmission method,reflection method and transflective method.Region area detection experiment in mining face had been carried out thanks to the advantage of channel wave,such as its great dispersion,abundant geology information,strong anti-interference ability and long-distance detecting.The experimental results showed that:(1)Coal seam thickness variation in extremely unstable coal seam has been quantitatively interpreted with an accuracy of more than 80%generally;(2)The faults,goafs and collapse columns could be detected and predicted accurately;(3)Experimental detection of gas enrichment areas,stress concentration regions and water inrush risk zone has been collated;(4)A research system of disaster-causing geology anomalous body detection by in-seam seismic survey has been built,valuable and innovative achievements have been got.Series of innovation obtained for the first time in this study indicated that it was more effective to detect disaster-causing potential geology anomalies by in-seam seismic survey than by ground seismic survey.It had significant scientific value and application prospect under complex coal seam conditions.

Recognition and depiction of special geologic bodies of Member 3 of Dongying Formation in Littoral Slope Zone,Qikou Sag

The purpose of this study is to forecast the profitable oil and gas reservoir,which is the key of finding hydrocarbon,based on the conception of special geologic bodies.With the guiding methodology of the research thinking of integration of point-line-surface by using the methods and techniques of logging,seismic,seismic attribute,and logging constrained inversion in 3D data volume,the special geologic bodies of Member 3 of Dongying Formation in Littoral Slope Zone of Qikou Sag,which has important hydrocarbon exploration potential,are recognized and described under the constraint of sequence stratigraphic framework.As a result,the developed scale,geometric shape and space distribution feature of the special geologic bodies are forecasted;the inner structure and sequence structure patterns of the geologic bodies are also ascertained.From the lowstand system tract (LST) and lacustrine expanding system tract (EST) to the highstand system tract (HST),the geologic bodies have evolved from relative centralization of lake basin reducing period to three relative dispersive isolated parts of broad lake basin period.According to the relevance and regularity of the development of geologic bodies,the conclusions can be obtained that three types of potential profitable reservoir traps,including the lithologic lens traps,lithologic updip pinchout traps and structural-lithologic composite traps,are forecasted.In addition,scientific basis for further hydrocarbon exploration in new area (few-well area and no-well area) is offered in the guidance of sequence stratigraphic model.

Recognition and Depiction of the Special Geologic Bodies of the Member 3 of Dongying Formation in Littoral Slope Zone,Qikou Sag

The key of finding hydrocarbon reservoir is to find the profitable oil and gas reservoir.This paper uses the conception of"special geologic bodies"to study the profitable reservoir.Constrained by the sequence stratigraphy framework,this paper recognizes and describes the special geologic bodies of the Member 3 of Dongying Formation in Littoral Slope Zone of Qikou Sag,which have important

COMPUTER SYSTEM FOR GEOMETRIC MODELING OF GEOLOGIC BODIES AND APPLICATIONS

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Geologic body three-dimensional model generation and visualization method

The divergence three-dimensional millet-seed body model and the continuous distributing layer-imitating model were introduced, which were used to express geologic body, and the procedure of generating these two models and their merits and demerits were synthesized. Three methods of geologic body’s three-dimensional expression were separately introduced, and the merits of the continuous distributing layer imitating model were proposed as comparing with the divergence three-dimensional millet-seed body model. The three-dimensional cubes were observed from any direction and any tangle with the application of dealing methods such as peeling, hollowing out, transparent or half-transparent.

PRELIMINARY STUDY ON GEOMETRIC MODELING OF GEOLOGIC BODY

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Reminiscences of Days as an Undergraduate at Caltech in the 1960s: Geology, Student Body Politics and Intercollegiate Football

From 1960 to 1964, I was an undergraduate student at the California Institute of Technology [Caltech] in Pasadena, California. During these years, I spent much of my time indulging in student body politics and playing intercollegiate football. However, with the encouragement of a number of faculty in the Division of Geological Sciences [not yet GPS], I saw the light and became a geology major [strictly speaking, geophysics]. This paper is an expansion of a talk I presented at the 90th Anniversary of the Division of Geological and Planetary Sciences in 2017.

FROM GEOLOGICAL MOVEMENT TO GLOBE'S MOVEMENT

The geological movement(1959) summarized the form of expression of thebasic contradictions in geoscientific objects of study, and it point out that one movement should in dependent the several other movements. Mr.considered, at a meeting on the problems of scientific philosophy in 1959,that the Geological Movement expressed the existing modeof inorganic Substances or mineral substances in individual celestial body. He said, further more,that the Geological Movement was the synthesis of several kind of movements, which is mechanistic movement, physical movement, chemical movement and biological movement.The Geological Movement was the result of considering the modern objects of geology and it showed the new developing achievements of geoscientific philosophy in this first century.

中国水层CO_(2)地质封存技术攻关方向

在国家“碳达峰碳中和”战略目标下,为了延长化石能源行业的生命周期,亟需进行大规模碳减排的重大革命,其中CO_(2)地质封存(CCS)这一大规模碳减排的托底技术,已在全球达成共识。为此,系统梳理了全球CCS发展趋势,并针对中国CCS地质特点和工程技术现状,分析了中国发展水层CCS面临的挑战和难点,提出了中国水层CO_(2)地质封存技术的攻关方向。研究结果表明:①中国水层CCS起步早,当前正在开展世界级规模水层CCS先导试验,技术水平与国外并行,CCS有望成为中国未来大规模碳减排的主要手段;②鉴于中国水层多无法回避陆相沉积、断裂发育、非均质性强等先天条件,中国未来建设大规模水层CCS将面临封存规模大、封存成本高和长期封存安全性等3个方面关键技术的挑战;③从推动和形成CCS负碳新产业角度,中国未来水层CCS碳埋存需要攻克CCS地质体评估、CO_(2)高速注入、低浓度CO_(2)封存、降低成本和地质监测等5个关键技术。结论认为,该研究认识进一步坚定了中国发展水层CCS技术的信心,提出的5个方面关键技术为快速形成负碳领域的国家战略科技力量明确了攻关方向,同时为后续推动大规模地下储氢、储氦、压缩空气储能等战略性新兴行业的发展提供了前瞻性技术支撑。

滇中引水工程隧洞综合超前地质预报分析及应用

针对隧洞施工过程中不同工程地质条件下何种超前地质预报方法预测更为准确、更为适用和单一方法精确度不够、适用性不强的问题,分别介绍了基于地震波法的长距离隧洞超前地质预报技术和基于电磁法的中、短距离隧洞超前地质预报技术原理及特点,依据其工作原理、工作方式、预报距离等特点,探讨了不同超前地质预报方法的优、缺点及其最适用的工作场景,总结出一套实用性强的综合超前地质预报流程。依托滇中引水工程大理Ⅱ段两个隧洞的工程实例,利用所提出的综合超前地质预报流程,分别介绍了结合长距离的隧道地震预报(TSP)法、中短距离的瞬变电磁法和探地雷达法对断层破碎带和裂隙水等不良地质体的综合预报研究。首先,通过长距离预报方法对地质灾害危险程度进行分级、识别高危地段,再通过短距离预报方法对不良地质体进行更精确的识别与定位,综合分析3种超前地质预报方法的地球物理响应特征,可以推断出不良地质体的类型及其空间分布特征;其次,通过探地雷达探测溶蚀波场特征的案例分析,可以推断出溶蚀的物性特征、规模及其空间分布特征。预报结果与隧洞掌子面开挖揭示的结果基本一致,验证了3种超前地质预报方法预报隧洞不良地质体的可靠性,也证实了所提出的综合超前地质预报流程的实用性,有助于指导物探工作者对不良地质体进行更精确的预报,确保隧洞施工安全。