Gravity tectonics controls on reservoir-scale sandbodies:Insights from 3D seismic geomorphology of the canyons buried in the upper slope of the Eastern Niger delta basin

High-resolution 3D seismic data analysis was integrated with a calibrated well and biostratigraphy data to present the first overview of a buried Pleistocene canyon system on the upper slope of the eastern Niger Delta,the Galabor Canyon.Attribute maps of specific horizons allow documenting the changing morphologies and infill lithologies of two main branches of the canyon through two stages of activity separated by a reference horizon dated at 0.99 Ma based on well calibration.At the upper slope,growth faults dissect the canyon heads,the catchment of which encroaches a network of valleys incised on the outer shelf.The canyon fill is composed of muddy channels and mass-transport deposits,largely derived from the collapse of canyon walls and sand-rich bodies forming a tract sourced by shelf-edge deltas at the outlet of the incised valleys.High-density turbiditic processes likely control the distribution of sand bodies along the canyon,ranging from tributary fans on the upper slope to 6 km-wide meander belts on the middle slope.The sandy deposits accumulate in minibasins formed along the canyon path,downstream of the subsiding hanging wall of the growth faults and upstream of shale ridges that damp the flow in the canyon.These results show that canyons can be major targets for sand reservoir exploration on the upper slope of large muddy deltas.

Application of 9-component S-wave 3D seismic data to study sedimentary facies and reservoirs in a biogasbearing area:A case study on the Pleistocene Qigequan Formation in Taidong area,Sanhu Depression,Qaidam Basin,NW China

To solve the problems in restoring sedimentary facies and predicting reservoirs in loose gas-bearing sediment,based on seismic sedimentologic analysis of the first 9-component S-wave 3D seismic dataset of China,a fourth-order isochronous stratigraphic framework was set up and then sedimentary facies and reservoirs in the Pleistocene Qigequan Formation in Taidong area of Qaidam Basin were studied by seismic geomorphology and seismic lithology.The study method and thought are as following.Firstly,techniques of phase rotation,frequency decomposition and fusion,and stratal slicing were applied to the 9-component S-wave seismic data to restore sedimentary facies of major marker beds based on sedimentary models reflected by satellite images.Then,techniques of seismic attribute extraction,principal component analysis,and random fitting were applied to calculate the reservoir thickness and physical parameters of a key sandbody,and the results are satisfactory and confirmed by blind testing wells.Study results reveal that the dominant sedimentary facies in the Qigequan Formation within the study area are delta front and shallow lake.The RGB fused slices indicate that there are two cycles with three sets of underwater distributary channel systems in one period.Among them,sandstones in the distributary channels of middle-low Qigequan Formation are thick and broad with superior physical properties,which are favorable reservoirs.The reservoir permeability is also affected by diagenesis.Distributary channel sandstone reservoirs extend further to the west of Sebei-1 gas field,which provides a basis to expand exploration to the western peripheral area.

Integrated application of 3D seismic and microseismic data in the development of tight gas reservoirs

The development of unconventional resources, such as shale gas and tight sane gas, requires the integration of multi-disciplinary knowledge to resolve many engineering problems in order to achieve economic production levels. The reservoir heterogeneit3 revealed by different data sets, such as 3D seismic and microseismic data, can more full3 reflect the reservoir properties and is helpful to optimize the drilling and completioT programs. First, we predict the local stress direction and open or close status of the natura fractures in tight sand reservoirs based on seismic curvature, an attribute that reveals reservoi heterogeneity and geomechanical properties. Meanwhile, the reservoir fracture network is predicted using an ant-tracking cube and the potential fracture barriers which can affec hydraulic fracture propagation are predicted by integrating the seismic curvature attribute anc ant-tracking cube. Second, we use this information, derived from 3D seismic data, to assis in designing the fracture program and adjusting stimulation parameters. Finally, we interpre the reason why sand plugs will occur during the stimulation process by the integration of 3E seismic interpretation and microseismic imaging results, which further explain the hydraulic fracure propagation controlling factors and open or closed state of natural fractures in tigh sand reservoirs.

Beamforming with the Generalized Sidelobe Cancellerfor Coherent Noise Attenuation in 3D Seismic Data

This paper presents a new approach for attenuating coherent noise in 3D seismic data. An adaptive beamforming with generalized sidelobe canceller (GSC) design methodology is utilized here as a general form of linearly constrained adaptive beamforming structure. It consists of a fixed beamformer, and a signal-blocking matrix in front of an unconstrained adaptive beamformer.Considerationf of the complexity of the geometry for 3D seismic survey, the 3D beamforming with GSC technique is developed with two key points: (1) sorting along azimuth sections to simplify the relationship between traveltime and offset from 3D to 2D, and (2) dynamic binning scheme to avoid the possible poor folding in some azimuth sections. Both simulation result and real data example show that the newly developed 3D beamforming with GSC yields more credible results at a relative low cost, sufficient stability and good resolution.

3D Seismic Acquisition Technology and Effect in HX Volcanic Area in Liaohe Depression

Multi-stages volcanic are available in HX area, shielding the seismic waves. Previous seismic acquisitions of large size bin, less fold coverage and narrow azimuth result in indistinct fault images, low S/N ratio and the difficulty of multi-stages volcanic characterization. In reference to the successful experience of domestic and overseas volcanic exploration, the low frequency excitation and receiving, and survey with wide range, high coverage, wide azimuth should be paid more attention, associated with two-dimensional and three-dimensional wave equation forward modeling and real data processing contrast analysis method. The image of underlying strata and fault are remarkably improved in the new method, according to the processing results of new seismic data. The new method will provide technical reference for the similar volcanic development area in the future seismic acquisition design.

Sedimentary microfacies of the H8 member in the Su14 3D seismic test area

The distribution of sedimentary microfacies in the eighth member of the Shihezi formation（the H8 member） in the Sul4 3D seismic test area was investigated.A Support Vector Machine（SVM） model was introduced for the first time as a way of predicting sandstone thickness in the study area.The model was constructed by analysis and optimization of measured seismic attributes.The distribution of the sedimentary microfacies in the study area was determined from predicted sandstone thickness and an analysis of sedimentary characteristics of the area.The results indicate that sandstone thickness predictions in the study area using an SVM method are good.The distribution of the sedimentary microfacies in the study area has been depicted at a fine scale.

Application of 3D Seismic Data Inversion to Coal Mining Prospecting

Seismic inversion is one of the most important methods for lithological prospecting . Seismic data with lowresolution is converted into impedance data of high resolution which can reflect the geological structure by inversionThe inversion technique of 3D seismic data is discussed from both methodological and theoretical aspects, and the in-version test is also carried out using actual logging data. The result is identical with the measured data obtained fromroadway of coal mine. The field tests and research results indicate that this method can provide more accurate data foridentifying thin coal seam and minor faults.

3D HIGH RESOLUTION SEISMIC PROSPECTING IN MINING AREAS,XIEQIAO COLLIERY

3D seismic prospecting in mining areas of Xieqiao Colliery is a successfulmodel for an advancement from the resource prospecting to mining prospecting stagein coal fields. Its results have proved that faults with a throw of 5-10 m can be detected in an area with good seismogeologic conditions by using 3D seismic technique.Detection of underground tunnels for the first time utilizing 3D seismic data indicates that subsided columns, gotten and mine goaf can be detected using 3D seismic technique, so it has a broad applied prospect.

Study on the 3D Seismic Data Field Hybrid Rendering Technique of Natural Gas Hydrate and Its Application

3D visualization technology is a tool used for displaying, describing, and understanding the characteristics of geologic bodies, and features high efficiency, objective accuracy, visual expression, etc. In this paper, the man-machine interactive interpretation and 3D visualization technology rapidly displaying and analyzing the 3D seismic data of hydrate ore volume is researched and developed using the hybrid rendering technique. Through the integrated interpretation on the 3D space structure, stratum, and seismic attributes, the visualized multi-attribute superimposition analysis is implemented for describing the spatial distribution characteristics of hydrate ore volume and exquisitely describing the subtle geological characteristics of hydrate ore volume. By the hybrid rendering technique, authentication and interpretation are provided for the geological exploration work, so as to greatly enhance the visualization and accuracy of the geological analysis, and also provide a good decision-making foundation for the subsequent development of resources.

3D HIGH RESOLUTION SEISMIC PROSPECTING IN COAL MINING AREAS

The production capacity and efficiency for mechanized coal faces of large-scale mines depend on the detecting degree of mining structures. It is a major task for geological exploration in coal fields to detect minor structures in district. 3D high resolution seismic prospecting is a effective measure for solving this problem.

Deep-large faults controlling on the distribution of the venting gas hydrate system in the middle of the Qiongdongnan Basin, South China Sea

Many locations with concentrated hydrates at vents have confirmed the presence of abundant thermogenic gas in the middle of the Qiongdongnan Basin(QDNB).However,the impact of deep structures on gasbearing fluids migration and gas hydrates distribution in tectonically inactive regions is still unclear.In this study,the authors apply high-resolution 3D seismic and logging while drilling(LWD)data from the middle of the QDNB to investigate the influence of deep-large faults on gas chimneys and preferred gasescape pipes.The findings reveal the following:(1)Two significant deep-large faults,F1 and F2,developed on the edge of the Songnan Low Uplift,control the dominant migration of thermogenic hydrocarbons and determine the initial locations of gas chimneys.(2)The formation of gas chimneys is likely related to fault activation and reactivation.Gas chimney 1 is primarily arises from convergent fluid migration resulting from the intersection of the two faults,while the gas chimney 2 benefits from a steeper fault plane and shorter migration distance of fault F2.(3)Most gas-escape pipes are situated near the apex of the two faults.Their reactivations facilitate free gas flow into the GHSZ and contribute to the formation of fracture‐filling hydrates.

Geological Interpretation and Identification of Albian-Aged Petroleum Prospects in Block A, San Pedro Margin (Côte d’Ivoire)

The study aims to identify Albian-age oil prospects in Block A of the San Pedro margin, Côte d’Ivoire, by conducting a detailed geological interpretation. The objective is to confirm the presence of oil reservoirs trapped by favorable geological structures, identifiable through geophysical and seismic methods. The methodological approach is based on a combined analysis of studies and seismic data. Drilling data from well PA, including well logs and end-of-well reports, were used to characterize the lithological formations encountered, particularly those of the Albian. 3D seismic profiles were interpreted to identify structures conducive to hydrocarbon accumulation. Isochrone, isovelocity, and isobath maps were developed to refine the interpretation. Sedimentological analyses revealed five sandy/gritty levels between 2610 m and 3100 m, interspersed with clay, limestone, and siltstone beds. The seismic profiles highlighted two main prospects. These prospects exhibit favorable geological structures, including normal faults and structural traps that provide oil traps.

CFD simulation on the generation of turbidites in deepwater areas: a case study of turbidity current processes in Qiongdongnan Basin, northern South China Sea

Turbidity currents represent a major agent for sediment transport in lakes, seas and oceans. In particu-lar, they formulate the most significant clastic accumulations in the deep sea, which become many of the world＇s most important hydrocarbon reservoirs. Several boreholes in the Qiongdongnan Basin, the north-western South China Sea, have recently revealed turbidity current deposits as significant hydrocarbon res-ervoirs. However, there are some arguments for the potential provenances. To solve this problem, it is es-sential to delineate their sedimentary processes as well as to evaluate their qualities as reservoir. Numerical simulations have been developed rapidly over the last several years, offering insights into turbidity current behaviors, as geologically significant turbidity currents are difficult to directly investigate due to their large scale and often destructive nature. Combined with the interpretation of the turbidity system based on high-resolution 3D seismic data, the paleotophography is acquired via a back-stripping seismic profile integrated with a borehole, i.e., Well A, in the western Qiongdongnan Basin; then a numerical model is built on the basis of this back-stripped profile. After defining the various turbidity current initial boundary conditions, includ-ing grain size, velocity and sediment concentration, the structures and behaviors of turbidity currents are investigated via numerical simulation software ANSYS FLUENT. Finally, the simulated turbidity deposits are compared with the interpreted sedimentary bodies based on 3D seismic data and the potential provenances of the revealed turbidites by Well A are discussed in details. The simulation results indicate that a sedimen-tary body develops far away from its source with an average grain size of 0.1 mm, i.e., sand-size sediment. Taking into account the location and orientation of the simulated seismic line, the consistence between normal forward simulation results and the revealed cores in Well A indicates that the turbidites should have been transported from Vietnam instead of Hainan Island. This interpretation has also been verified by the planar maps of sedimentary systems based on integration of boreholes and seismic data. The identification of the turbidity provenance will benefit the evaluation of extensively distributed submarine fans for hydro-carbon exploration in the deepwater areas.

Near-surface absorption compensation technology and its application in the Daqing Oilfields

High-frequency seismic data components can be seriously attenuated during seismic wave propagation in unconsolidated （low-velocity） layers, resulting in reduced seismic resolution and signal-to-noise （S/N） ratio. In this paper, first, based on Wiener filter theory, inverse filter calculations for near-surface absorption attenuation compensation were accomplished by analysis of the direct wave spectral components from different distances near the surface. The direct waves were generated by detonators in uphole shots and were acquired by receivers on the surface. The spatially varying inverse filters were designed to compensate for the frequency attenuation of 3D pre-stack CRG （common receiver-gather） data. After applying the filter to CRG data, the high frequency components were compensated with the low frequencies maintained. The seismic resolution and S/N ratio are enhanced and match better with synthetic seismograms and better meet the needs of geological interpretation.

Upper Crustal Velocity Structure along the Yangtze River from Ma'anshan to Anqing

We applied the 3D first arrival travel time tomography method to the Anhui active seismic source experiment data,and obtained the imaging of the upper crust velocity structure beneath the Yangtze River from Ma'anshan,Tongling to Anqing. Data fitting reveals the tomographic model fits the data with uncertainties, without overfitting, and with a minimum of complexity. The tomographic result shows an obvious heterogeneous upper crust which consists of a series of uplifts and depression basins. The velocity model and region imply that this region has experienced crustal uplift and extensional tectonism with concomitant magmatism since the Cenozoic.

Seismic geomorphology and stratigraphic trap analyses of the Lower Cretaceous siliciclastic reservoir in the Kopeh Dagh-Amu Darya Basin

Lower Cretaceous Shurijeh–Shatlyk Formations host some of the main reservoirs in the Kopeh Dagh-Amu Darya Basin.Exploration in this area so far has focused on the development of structural traps, but recognition of stratigraphic traps in this area is of increasing importance. Integration of 3D seismic data with borehole data from thirteen wells and five outcrop sections was used to identify potential reservoir intervals and survey the hydrocarbon trap types in the East Kopeh Dagh Foldbelt(NE Iran). Analyses of horizontal slices indicated that the lower Shurijeh was deposited in a braided fluvial system.Generally, three types of channel were identified in the lower Shurijeh Formation: type 1, which is low-sinuosity channels interpreted to be filled with non-reservoir fine-grained facies;type 2, which is a moderately sinuous sand-filled channel with good prospectively;and type 3, which is narrow, high sinuosity channel filled with fine-grained sediments. Results indicate that upper Shurijeh–Shatlyk Formations were deposited in fluvial to delta and shallow marine environments. The identified delta forms the second reservoir zone in the Khangiran Field. Study of the stratigraphic aspects of the Shurijeh succession indicates that both lower and upper Shurijeh reservoirs are stratigraphic reservoir traps that improved during folding.

Mapping of thin sandstone reservoirs in bisol field, Niger delta, Nigeria using spectral decomposition technique

This study focuses on using spectral decomposition(SD)technique to characterize complicated reservoirs to understand the structural and stratigraphic variations in the interpreted horizons from Bisol field.The purpose of this study is to use geophysical and well logging data sets to map the thin-bedded sandstone reservoirs and prospect zones within the multiple reservoirs in Bisol field,Niger Delta.The interpretation of faults and horizons was carried out on the seismic section,which was further used to produce the structural maps.Seismic attributes such as trace and variance were used to enhance the truncated structures from the seismic section,while the produced spectra were used to delineate the stratigraphy and thickness of the thin-bedded reservoirs.Thin sandstone reservoirs were identified from well logs and consequently mapped on the seismic section.Fast Fourier Transform workflow was successfully used to image the stratigraphic features in the study area.Three horizons(S1T,S2T and S3T)were delineated from the seismic section,and four reservoirs were mapped and correlated across the wells.Frequency analyses from the seismic sectional view revealed some thin pay sandstone reservoirs,which were characterized by high amplitude.Three new probable zones(Prospect A,B and C)of hydrocarbon accumulation were identified using the SD technique.

Resolution assessment of the three-dimensional acquisition geometry of the Anhui experiment in"Geoscience Yangtze Plan"

According to the actual observation conditions of the Yangtze River valley from Anqing city to Maanshan city,we designed the 3D acquisition geometry,and applied the multi-scale checkerboard semblance analysis to assess the preliminary resolution of the designed observation.The checkerboard semblance tests use the refraction and reflection travel-time simultaneous inversion algorithm to quantitatively provide both resolution assessment of velocity structure and Moho topography.The multi-scale checker-board semblance recovery results show that while the chec-kerboard semblance threshold value is 0.5,the preliminary resolution of the designed acquisition geometry is better than 10 km in the upper crust(the depth is less than 10 km),around 15 km in the mid-crust(the depth is 10?25 km),and better than 20 km in the lower crust(the depth is 25?33 km).The preliminary tomographic resolution for the Moho topography is about 20 km in the ray-path coverage area beneath the acquisition geometry.While the checkerboard semblance threshold value is 0.75,the preliminary resolution is 20 km in the upper crust,around 20?25 km in the mid-crust and 25 km in the lower crust.And the preliminary tomographic resolution for the Moho topography is better than 30 km in the ray-path coverage area beneath the acquisition geometry.These non-linear checkerboard tests reveal that the designed acquisition geometry is suitable to image the crustal velocity structure of the Yangtze River valley in the Anhui province.

Proposal of Indonesia Seismic Hazard Deaggregation Maps for Sumatra, Indonesia

The new method for determining ground-motion parameters in the Indonesian Earthquake Resistant Building Code SNI （Indonesia National Standard） 03-1726-2012 has significant changes than the previous code. The maps of mean and modal of magnitude and distance presented here are intended to convey information about the distribution ofprobabilistic seismic sources and to provide prescriptions or suggestions for seismic sources to use in developing artificial ground motion in building design or retrofit projects. This paper presents deaggregation of Indonesia Seismic Hazard Map 2010 for Sumatra. Deaggregation for 0.2-s and 1.0-s pseudo SA （spectral acceleration） is performed for 10% PE （probability of exceedance） in 50 years （475-year mean return period） and 2% PE in 50 years （2,475-year mean return period）. The information of deaggregation analysis can and perhaps should be considered in a complex seismic-resistant design decision-making environment.

Land 3D-Seismic Data: Preprocessing Quality Control Utilizing Survey Design Specifications, Noise Properties, Normal Moveout, First Breaks, and Offset

The recent proliferation of the 3D reflection seismic method into the near-surface area of geophysical applications, especially in response to the emergence of the need to comprehensively characterize and monitor near-surface carbon dioxide sequestration in shallow saline aquifers around the world, justifies the emphasis on cost-effective and robust quality control and assurance （QC/QA） workflow of 3D seismic data preprocessing that is suitable for near-surface applications. The main purpose of our seismic data preprocessing QC is to enable the use of appropriate header information, data that are free of noise-dominated traces, and/or flawed vertical stacking in subsequent processing steps. In this article, I provide an account of utilizing survey design specifications, noise properties, first breaks, and normal moveout for rapid and thorough graphical QC/QA diagnostics, which are easy to apply and efficient in the diagnosis of inconsistencies. A correlated vibroseis time-lapse 3D-seismic data set from a CO2-flood monitoring survey is used for demonstrating QC diagnostics. An important by-product of the QC workflow is establishing the number of layers for a refraction statics model in a data-driven graphical manner that capitalizes on the spatial coverage of the 3D seismic data.