Applying Source Parameter Imaging (SPI) to Aeromagnetic Data to Estimate Depth to Magnetic Sources in the Mamfe Sedimentary Basin

Aeromagnetic data over the Mamfe Basin have been processed. A regional magnetic gridded dataset was obtained from the Total Magnetic Intensity (TMI) data grid using a 3 × 3 convolution (Hanning) filter to remove regional trends. Major similarities in magnetic field orientation and intensities were observed at identical locations on both the regional and TMI data grids. From the regional and TMI gridded datasets, the residual dataset was generated which represents the very shallow geological features of the basin. Processing this residual data grid using the Source Parameter Imaging (SPI) for magnetic depth suggests that the estimated depths to magnetic sources in the basin range from about 271 m to 3552 m. The highest depths are located in two main locations somewhere around the central portion of the study area which correspond to the area with positive magnetic susceptibilities, as well as the areas extending outwards across the eastern boundary of the study area. Shallow magnetic depths are prominent towards the NW portion of the basin and also correspond to areas of negative magnetic susceptibilities. The basin generally exhibits a variation in depth of magnetic sources with high, average and shallow depths. The presence of intrusive igneous rocks was also observed in this basin. This characteristic is a pointer to the existence of geologic resources of interest for exploration in the basin.

Discharge Simulation in a Data-Scarce Basin Using Reanalysis and Global Precipitation Data: A Case Study of the White Volta Basin

Basins in many parts of the world are ungauged or poorly gauged, and in some cases existing measurement networks are declining. The purpose of this study was to examine the utility of reanalysis and global precipitation datasets in the river discharge simulation for a data-scarce basin. The White Volta basin of Ghana which is one of international rivers was selected as a study basin. NCEP1, NCEP2, ERA-Interim, and GPCP datasets were compared with corresponding observed precipitation data. Annual variations were not reproduced in NCEP1, NCEP2, and ERA-Interim. However, GPCP data, which is based on satellite and observed data, had good seasonal accuracy and reproduced annual variations well. Moreover, five datasets were used as input data to a hydrologic model with HYMOD, which is a water balance model, and with WTM, which is a river model;thereafter, the hydrologic model was calibrated for each datum set by a global optimization method, and river discharge were simulated. The results were evaluated by the root mean square error, relative error, and water balance error. As a result, the combination of GPCP precipitation and ERA-Interim evaporation data was the best in terms of most evaluations. The relative errors in the calibration and validation periods were 43.1% and 46.6%, respectively. Moreover, the results for the GPCP precipitation and ERA-Interim evaporation were better than those for the combination of observed precipitation and ERA-Interim evaporation. In conclusion, GPCP precipitation data and ERA-Interim evaporation data are very useful in a data-scarce basin water balance analysis.

3D Modelling from New and Existing Gravity Data of an Intrusive Body in the Northern Part of Kribi-Campo Sub-Basin in Cameroon

A new gravity survey was carried out in the northern part of the onshore Kribi- Campo sub-basin in Cameroon. The data were incorporated to the existing ones and then analyzed and modeled in order to elucidate the subsurface structure of the area. The area is characterized in its north-western part by considerably high positive anomalies indicative of the presence of a dense intrusive body. We find, 1) from the analysis of the gravity residual anomaly map, the high positive anomalies observed are the signature of a shallow dense structure;2) from the multi-scale analysis of the maxima of the horizontal gradient, the structure is confined between depths of 0.5 km and 5 km;3) from the quantitative interpretation of residual anomalies by spectral analysis, the depth to the upper surface of the intrusive body is not uniform, the average depth of the bottom is h1 = 3.6 km and the depths to particular sections of the roof of the intrusion are h2 = 1.6 km and h3 = 0.5 km;4) and the 3D modeling gives results that are suggestive of the presence of contacts between rocks of different densities at different depths and a dense intrusive igneous body in the upper crust of the Kribi zone. From the 3D model the dense intrusive igneous block is surrounded by sedimentary formations to the south-west and metamorphic formations to the north-east. Both formations have a density of about 2.74 g/cm3. The near surface portions of this igneous block lie at a depth range of 0.5 km to 1.5 km while its lower surface has a depth range of 3.6 km to 5.2 km. The shape of the edges and the bottom of the intrusive body are suggestive of the fact that it forms part of a broader structure underlying the Kribi-Campo sub-basin with a great influence on the sedimentary cover.

“Deep-time Digital Basin” Based on Big Data and Artificial Intelligence

1 Introduction Information technology has been playing an ever-increasing role in geoscience.Sphisicated database platforms are essential for geological data storage,analysis and exchange of Big Data(Feblowitz,2013;Zhang et al.,2016;Teng et al.,2016;Tian and Li,2018).The United States has built an information-sharing platform for state-owned scientific data as a national strategy.

Paleostress Reconstruction from 3D Seismic Data and Slip Tendency in the Northern Slope Area of the Bongor Basin, Southwestern Chad

Paleostress plays a significant role in controlling the formation, accumulation, and distribution of reservoirs, and this could be an important factor in controlling the production of hydrocarbons from the unconventional reservoirs. In this study, we will use 3D seismic reflection data to perform the slip-tendency-based stress inversion to determine the stress field in the basement of the northern slope area in the Bongor Basin. The dataset for this technique is easily available in the oil and gas companies. The stress inversion results from the basement of the northern slope area of Bongor basin show that the maximum principal stress axis (σ1) is oriented vertically, the intermediate principal stress axis (σ2) is oriented N18° and the minimum principal stress axis (σ3) is oriented N105°, and σ2/σ1 = 0.60 and σ3/σ1 = 0.29. The findings of this paper provide significant information to understand the fault reactivation at the critical stage of hydrocarbon accumulation and the regional tectonic evolution.

Determination of Hydrocarbon Potentials Using High Resolution Aeromagnetic Data over Sokoto Basin, Northwestern Nigeria

Aeromagnetic method of exploration is famed for its suitability for locating buried magnetic ore bodies because of their magnetic susceptibility. This method has been used in the early stage of petroleum exploration to determine depth and major structures of crystalline Basement rocks underlying the sedimentary basin. In this study, high resolution aeromagnetic data were used to ascertain the viability for hosting hydrocarbon potentials of the study area which forms part of the Illummeden Basin (also known locally as the Sokoto embayment) of West Africa. This was largely carried out through Spectra analysis to determine sediment thickness. The results of the analysis of the aeromagnetic data show that, deeper magnetic source ranges from 0.41 km to 2.69 km, shallow magnetic sources from 0.17 km to 0.97 km. Areas with shallow sediment thickness could not allow the thermal maturation of the sediments, since temperature increase with depth and a depth of two kilometers and above has a temperature range of 60°C and above. Areas with sediment thickness of 1.5 km and above were delineated and considered as sub-basins and hence potential areas for hydrocarbon exploration.

Determination of Curie Point Depth and Heat Flow Using Airborne Magnetic Data over the Kom-Ombo and Nuqra Basins, Southern Eastern Desert, Egypt

The Kom-Ombo and Nuqra basins in southern Egypt have recently been discovered as potential hydrocarbon basins. The lack of information about the geothermal gradient and heat flow in the study area gives importance to studying the heat flow and the geothermal gradient. Several studies were carried out to investigate the geothermal analyses of the northwestern desert, as well as the west and east of the Nile River, using density, compressive wave velocity, and bottom hole temperature (BHT) measured from deep oil wells. This research relies on spectral analysis of airborne magnetic survey data in the Kom-Ombo and Nuqra basins in order to estimate the geothermal gradient based on calculating the depth to the bottom of the magnetic source that caused the occurrence of these magnetic deviations. This depth is equal to the CPD, at which the material loses its magnetic polarisation. This method is fast and gives satisfactory results. Usually, it can be applied as a reconnaissance technique for geothermal exploration targets due to the abundance of magnetic data. The depth of the top (Zt) and centroid (Z0) of the magnetic source bodies was calculated for the 32 windows representing the study area using spectral analysis of airborne magnetic data. The curie-isotherm depth, geothermal gradient, and heat flow maps were constructed for the study area. The results showed that the CPD in the study area ranges from 13 km to 20 km. The heat flow map values range from 69 to 109 mW/m2, with an average of about 80 mW/m2. The calculated heat flow values in the assigned areas (A, B, C, and D) of the study area are considered to have high heat flow values, reaching 109 mW/m2. On the other hand, the heat flow values in the other parts range from 70 to 85 mW/m2. Since heat flow plays an essential role in the maturation of organic matter, it is recommended that hydrocarbon accumulations be located in places with high heat flow values, while deep drilling of hydrocarbon wells is recommended in places with low to moderate heat flow values.

Determination of Structural and Geometrical Parameters of the Kribi-Campo Sedimentary Sub-Basin Using Gravity Data

In order to produce a more detailed structural and geometrical information, and determine sediments thickness along the Kribi-Campo sub-basin, statistical spectral analysis and horizontal gradient analysis of residual anomalies coupled with the Euler deconvolution approach were applied on the gravity data in the area. The results obtained from the 2D spectral analysis on anomaly grids gave a depth to the basement rocks of the basin from 0.60 km to 3.93 km. This represents the thickness of the sedimentary formations overlying the basement. The interpretation of the spectral analysis results indicated that the potential hydrocarbon field areas are situated between Kribi and Lolabe and at Campo given that those areas have the highest sedimentary thicknesses values. From the analysis of the horizontal gradient, deep faults mainly striking SW-NE have been traced and a structural map of the area has been produced. By applying the Euler deconvolution method to the gravity data, information about the depth and trend of the main subsurface structures have been obtained.

Turbidite Dynamics and Hydrocarbon Reservoir Formation in the Tano Basin: A Coastal West African Perspective

This study examines the turbidite dynamics and hydrocarbon reservoir formation in Ghana’s Tano Basin, which is located in coastal West Africa. Through an exploration of geological processes spanning millions of years, we uncover key factors shaping hydrocarbon accumulation, including source rock richness, temperature, pressure, and geological structures. The research offers valuable insights applicable to exploration, management, and sustainable resource exploitation in coastal West Africa. It facilitates the identification of exploration targets with higher hydrocarbon potential, enables the anticipation of reservoir potential within the Tano Basin, and assists in tailoring exploration and management strategies to specific geological conditions of the Tano Basin. Analysis of fluvial channels sheds light on their impact on landscape formation and hydrocarbon exploration. The investigation into turbidite systems unveils intricate interactions involving tectonics, sea-level fluctuations, and sedimentation patterns, influencing the development of reservoirs. An understanding of sediment transport and depositional settings is essential for efficient reservoir management. Geomorphological features, such as channels, submarine canyons, and distinct channel types, are essential in this situation. A detailed examination of turbidite channel structures, encompassing canyons, channel complexes, convex channels, and U-shaped channels, provides valuable insights and aids in identifying exploration targets like basal lag, channel levees, and lobes. These findings underscore the enduring significance of turbidite systems as conduits for sediment transport, contributing to enhanced reservoir management and efficient hydrocarbon production. The study also highlights how important it is to examine the configuration of sedimentary layers, stacking patterns, and angular laminated facies to identify turbidites, understand reservoir distribution, and improve well design. The dynamic nature of turbidite systems, influenced by basin characteristics such as shape and slope, is highlighted. The research provides valuable insights essential for successful hydrocarbon exploration, reservoir management, and sustainable resource exploitation in coastal West Africa.

Evaluation of Water Losses by Evaporation in the Nakanbe Basin

A numerical approach to heat and mass transfer in a large water reservoir is presented. This water reservoir is likened to a parallelepiped reservoir whose vertical and lower walls are adiabatic and impermeable. The equations that govern natural convection in water are solved by the finite volume method and Thomas’salgorithm. The adequacy between the velocity and pressure fields is ensured by the SIMPLE algorithm. We are going to evaluate the water losses by evaporation from three dams in the Nakanbé basin in Burkina Faso for a period of thirty years, that is to say from January 1, 1991, to March 15, 2020. The three dams have a rate of evaporation greater than 40% of the volume of water stored. Indeed the rate of evaporation in each dam increases with the water filling rate in the reservoir: we have observed the following results for each dam in the Nakanbé basin;for the date of 02/27/1988 to 03/13/2020., the Loumbila dam received a total volume of stored water of 22.02 Mm3 and 10.57 Mm3 as the total volume of water evaporated at the same date. At the Ouaga dam (2 + 3), it stored a water volume of 4.06 Mm3 and evaporated 2.03 Mm3 of its storage volume from 01/01/1988 to 05/07/2016. Finally, with regard to the Bagré dam, it stored 745.16 Mm3 of water and 365.13 Mm3 as the volume of water evaporated from 01/01/1993 to 03/31/2020.

重力数据LTHG均衡边界识别方法对比分析及其应用

重力数据的边界识别技术有助于确定地质体或地质构造的边界。近年来涌现出多种边界识别方法,但各种方法的应用条件与处理效果存在差异,为深入了解这些方法的优缺点,便于实际资料处理解释时方法选取具有针对性,需要对各方法效果进行对比总结。针对常用导数类边界识别方法存在异常幅度随地质体埋深增加而迅速衰减的情况,基于理论模型的合成重力数据,分别在只存在重力正异常、同时存在重力正负异常及在同时存在正负异常重力数据中添加有高斯噪声三种情况下,开展了基于Logistic函数及总水平导数的边界增强法(LTHG)与常用总水平梯度(THG)、解析信号(AS)、倾斜角法(TDR)、倾斜角的总水平导数法(THDR)、总水平梯度的倾斜角法(TTHG)、解析信号的倾斜角法(TAS)、Theta图法(TM)、归一化总水平导数垂向导数法(NVDR_THDR)九种边界识别方法的对比研究,分析各方法在对不同埋深场源体的均衡能力、分辨能力及抗噪能力等方面的适用性及应用效果。研究结果表明:LTHG法的识别结果不依赖于场的埋藏深度,可很好地识别出不同埋深的场源边界,与其他常用方法相比LTHG法可提供准确、清晰、分辨率更高的场源体边界信息,最后将该方法应用于埃塞俄比亚欧加登盆地中部的航空重力资料处理中,处理结果与研究区的断裂构造有较好的相关性,同时又显示了更多的地质现象,应用效果较好。LTHG法在埋深均衡、分辨力及抗噪性各方面表现有优势,可以在生产实际中推广。

Analyzing the Mara River Basin Behaviour through Rainfall-Runoff Modeling

Hydrological models are considered as necessary tools for water and environmental resource management. However, modelling poorly gauged watersheds has been a challenge to hydrologists and hydraulic engineers. Research done recently has shown the potential to overcome this challenge through incorporating satellite based hydrological and meteorological data in the measured data. This paper presents results for a study that used the semi-distributed conceptual HBV Light Model to model the rainfall-runoff in the Mara River Basin, Kenya. The model simulates runoff as a function of rainfall. It is built on the basis established between satellite observed and in-situ rainfall, evaporation, temperature and the measured runoff. The model’s performance and reliability were evaluated over two sub-catchments namely: Nyangores and Amala in the Mara River Basin using the Nash-Sutcliffe Efficiency which the model referred to as Reff and the coefficient of determination (R2). The Reff for Nyangores and Amala during the calibration and (validation) period were 0.65 (0.68) and 0.59 (0.62) respectively. The model showed good flow simulations particularly during the recession flows, in the Nyangores sub-catchment whereas it simulated poorly the short term fluctuations of the high-flow for Amala sub-catchment. Results from this study can be used by water resources managers to make informed decision on planning and management of water resources.

Development of Overpressure in the Tertiary Damintun Depression, Liaohe Basin, Northern China

The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potenti

The Research and Application of BP Neural Networks in River-basin Water and Sediment

Based on the basic principles of BP artificial neural network model and the fundamental law of water and sediment yield in a river basin, a BP neural network model is developed by using observed data, with rainfall conditions serving as affecting factors. The model has satisfactory performance of learning and generalization and can be also used to assess the influence of human activities on water and sediment yield in a river basin. The model is applied to compute the runoff and sediment transmission at Xingshan, Bixi and Shunlixia stations. Comparison between the results from the model and the observed data shows that the model is basically reasonable and reliable.

Logging Data High-Resolution Sequence Stratigraphy

The recognition and contrast of bed sets in parasequence is difficult in terrestrial basin high-resolution sequence stratigraphy. This study puts forward new methods for the boundary identification and contrast of bed sets on the basis of manifold logging data. The formation of calcareous interbeds, shale resistivity differences and the relation of reservoir resistivity to altitude are considered on the basis of log curve morphological characteristics, core observation, cast thin section, X-ray diffraction and scanning electron microscopy. The results show that the thickness of calcareous interbeds is between 0.5 m and 2 m, increasing on weathering crusts and faults. Calcareous interbeds occur at the bottom of a distributary channel and the top of a distributary mouth bar. Lower resistivity shale （4-5 Ω · m） and higher resistivity shale （〉 10Ω·m） reflect differences in sediment fountain or sediment microfacies. Reservoir resistivity increases with altitude. Calcareous interbeds may be a symbol of recognition for the boundary of bed sets and isochronous contrast bed sets, and shale resistivity differences may confirm the stack relation and connectivity of bed sets. Based on this, a high-resolution chronostratigraphic frame- work of Xi-1 segment in Shinan area, Junggar basin is presented, and the connectivity of bed sets and oil-water contact is confirmed. In this chronostratigraphic framework, the growth order, stack mode and space shape of bed sets are qualitatively and quantitatively described.

新疆开孔河流域地下水依赖型植被生态系统的遥感识别

在干旱-半干旱地区,识别地下水依赖型植被生态系统(GDVEs)的位置和范围,对水资源和生态环境保护至关重要。针对传统识别方法的不足,以新疆开孔河流域为研究区,探索基于遥感技术的GDVEs识别方法。选取相对干旱年为研究期,基于植被指数、土壤湿度和潜在蒸散发,利用叠加分析和自然间断点分级法,确定开孔河流域GDVEs的空间分布,利用湿地分布、河流影响带及野外实地调查数据对识别结果进行验证。结果表明:开孔河流域GDVEs较高和高潜力区主要位于博斯腾湖周围和孔雀河下游荒漠平原区,主要为湿地生态系统和荒漠河岸林植被生态系统,约占天然植被区面积的10.3%;验证表明,本文提出的GDVEs识别方法可在西北干旱内陆河流域推广。

数字孪生北江流域建设实践与成效

针对北江流域洪水灾害频发的现状,为提升北江流域防洪减灾能力,广东省水利厅组织建设数字孪生北江流域。数字孪生北江流域基于广东省大数据、模型和知识等平台的公共能力,聚焦防洪联合优化调度,通过北江流域水库、蓄滞洪区、水闸、分洪河道、堤防等组成的“蓄、行、滞、分”防洪工程体系与数字孪生技术的深度耦合,协同优化多工程群组“上调、中控、下分”联动,搭建预报预警—工程调度—河道演进—精细模拟—风险研判—预案执行的全链条“四预”框架。数字孪生北江流域有效支撑“22·6”北江特大洪水、北江2024年第1号洪水的防御工作,相关成果已推广复用至数字孪生水网、数字孪生东江流域等。

松辽盆地西南部砂岩型铀矿地震资料处理技术研究

文章针对松辽盆地西南部砂岩型铀矿地震资料噪声严重,干扰波能量比较强,资料频带窄、主频低、以及地震记录单炮之间、深浅层和远近道之间能量差异比较大的特点,在地震资料处理的叠前去噪、振幅补偿以及提高分辨率等关键环节开展了研究。在去噪环节,采用了叠前多域组合分步去噪方法,针对性地去除面波、线性噪声、强能量干扰以及次生干扰等,增强了目的层有效反射信号强度,提高地震资料信噪比。在振幅补偿中采用地表一致性振幅补偿和几何扩散补偿方法,可以明显消除远近道、浅层与深层之间以及道间能量差异。在提高分辨率环节通过地表一致性反褶积和预测反褶积方法,可消除地震波传播过程中子波变化引起的波形、频谱等特征的差异,压缩子波,缩小子波旁瓣,拓宽有效信号频带,提高地震资料分辨率。最后建立了一套地震资料的处理流程,并建立了相应环节的质量监控措施。通过与前人处理结果对比,此次建立的地震资料处理方法可以明显提高地震资料的品质。

数字孪生淠河建设实践与思考

数字孪生淠河根据淠河流域特征,以流域防洪需求为牵引,提出技术解决方案。在共享安徽省现有数据感知、网络传输、算力环境等基础上,建设内容包括流域数据底板、水利模型平台、水利知识平台等支撑平台,以及在上述支撑平台基础上建立防洪预报、预警、预演、预案“四预”应用。防洪“四预”应用以精细化洪水预报为预警、调度提供基础,洪水预警为下游圩区等保护对象提供多阶段预警,情景化洪水预演以实景化方式分析洪水影响,智能化方案实现防洪预案的快速、自动化生成。通过总结数字孪生淠河建设内容,进一步探讨数字孪生流域建设中存在的难点问题,为相关数字孪生流域建设提供借鉴。

松辽流域生态环境时空动态评价及驱动因素分析

目前,我国高度重视以流域为基础的生态文明建设。及时有效的评估流域生态环境质量时空变化并分析其驱动因素对于制定流域协同性保护以及以流域为基础的生态文明建设十分重要。本文基于以数据为关键要素的,依托于遥感产品得到的绿度指数、湿度指数、干度指数、热度指数四项指标运用主成分分析方法建立松辽流域生态环境评估模型,并探索生态环境质量变化情况及其原因。结果表明:①松辽流域的生态环境质量整体优良,呈“东北优,西南差”的空间分布。②2000-2020年,松辽流域生态质量总体呈变好局势。第一个十年生态质量得到巨大改善,第二个十年处于生态保护维护阶段。③从空间分布上看,生态评级较差及以下等级面积明显收缩,优良等级面积显著向外扩张。④人类的社会经济生产活动对于生态环境的质量评估有至关重要的作用,如何平衡社会经济生产与生态环境保护之间的关系是帮助生态环境恢复的关键。