85th EAGE Annual Conference & Exhibition
- Conference date: June 10-13, 2024
- Location: Oslo, Norway
- Published: 10 June 2024
1 - 20 of 1031 results
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An Effective Harmonics Decomposition Method for Vibroseis Ground-Force Signals
More LessAuthors Y. Sun, M. Mubarak and H. MarzooqSummaryHarmonics contamination is an unavoidable phenomenon for ground-force signals generated by a Vibroseis truck. To enhance the quality of seismic data, it is preferred to use the fundamental mode of the ground-force signal, instead of the pilot sweep, to cross-correlate the measured raw seismic data. We present an effective harmonics decomposition method to separate different orders of harmonics from the ground-force signal of a Vibroseis truck. Our method builds a mathematical model for all orders of harmonics in the analytical signal domain, and inverts different orders of harmonics via solving an overdetermined linear equation. We use a synthetic example and a field data example to demonstrate the success of our proposed method.
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Identification Methods for Weakly Reflective Reservoirs Beneath Strong Shielding Horizons
More LessSummaryThis paper investigates identification methods for weakly reflective reservoirs located beneath strong shielding horizons. The study focuses on two commonly used techniques: multi-wavelet decomposition and the reconstruction method based on eigenvalue decomposition in the frequency domain, known as matching pursuit. Through case studies using actual seismic data from the Dongying Depression, the effectiveness of these methods is demonstrated in enhancing the visibility of weakly reflective reservoirs and improving their correlation with other well-log curves. The study also explores the application of the generalized S-transform and waveform shaping techniques in the seismic data processing workflow. The findings contribute to advancing the understanding and utilization of these methods for improved reservoir characterization and exploration in areas with strong shielding horizons.
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A Case Study of Reservoir Evaporative Fractionation in North Ghadames Basin, Libya
More LessSummaryThe Ghadames Basin, a prolific petroliferous basin spans areas from Libya, Tunisia and Algeria. It is a large intracratonic sag basin (∼350,000 km2) formed during Early Palaeozoic. The Libyan side of the Ghadames Basin covers approximately 2/3 of the basin. The Silurian, Lower Akakus and basal Hotshale of the Tanezzuft Formation are the primary reservoir and source in the northern Ghadames Basin. Oils with different properties were discovered in Well A in the Devonian, Awaynat Wanin Sand and Silurian, Akakus Reservoir.
Organic geochemical analysis was carried out on these two oils and source rocks in Well A and nearby wells.
Light oil was emplaced in the SAR from early-mid mature Hotshale in Well A; expulsion started in Upper Cretaceous. Subsequently the reservoir fractionation of the oil occurred due to high reservoir temperature in Well A with the preferential removal of normal Alkanes (nC17). The lighter fraction of the hydrocarbon migrated up dip through the fault to the DAWS and heavier fractions remained in SAR. This resulted in occurrence and discovery of two oils with different properties in Well A.
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Reconstructing Sparse Images of Drill Cuttings using a Convergent POCS Method on a Raspberry Pi
More LessAuthors Y. Sun and M. Al IbrahimSummaryReal-time data analysis on drill cuttings images can greatly improve the efficiency of drilling operations. A low-power computation platform is preferred for this task because it is a challenge to provide reliable and stable power supplies directly in the field. Raspberry Pi is a popular edge-computing platform. Due to its low-power consumption and versatile computation capabilities, it has powered plenty of realistic real-time edge-computing applications. However, its low I/O throughput is a grand challenge for acquiring high-resolution drill cuttings images efficiently. One solution to effectively increase its I/O throughput is to only acquire a sparse portion of the original drill cuttings image and reconstruct it at a later stage when it is no longer time sensitive. We demonstrate the feasibility of using a Convergent POCS (CP) method running on a Raspberry Pi 4B device for reconstructing sparse images of drill cuttings. Our work paves the way to further exploit high-performance edge-computing solutions for automatically analyzing drill cuttings in real time.
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Ultra-fast diffraction separation in the five-dimensional domain
More LessAuthors N. Okita, T.A. Coimbra and J.H. FaccipieriSummaryA deep and comprehensive analysis of seismic wave diffraction responses is crucial for refining seismic dataset modeling, imaging, and interpretation. Despite the advancements in using five-dimensional domain (5D) seismic response datasets, effectively isolating and highlighting diffractions in a hyper-volume for proper analysis remains computationally challenging. Using a modification of the Evolution by Neighborhood Similarity (ENS) method, we suppress theoretical limitations imposed for global optimization strategies in sample-by-sample traveltime-parameter searching. Leveraging data from neighboring inlines and crosslines enhances the co-evolutionary algorithm’s information exchange, aiming to expedite convergence and improve consistency in the regularized dataset. The proposed modification of the ENS method proves highly effective in a 5D seismic dataset, markedly reducing the required iterations for parameter estimation compared to traditional Differential Evolution (DE). This modification successfully separates diffractions in both zero- and common-offset sections, highlighting its efficacy. Notably, numerical experiments on a 3D land acquisition dataset demonstrate a significant improvement in execution time, with the modified ENS approach requiring up to thirty times less time for similar computations than DE. Moreover, the adapted ENS strategy achieves superior coherence in the region of interest, establishing its suitability and efficiency for enhancing and regularizing 5D diffraction datasets.
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Strontium Isotope and Element Constraints on the Paleoenvironment of the Latest Ediacaran in the Sichuan Basin
More LessAuthors X. ZhangSummaryThe Sichuan Basin, located in the southeastern margin of the plateau, is controlled by the fracturing of the peripheral block and tectonic movement of the basement. During the Neoproterozoic period, the Sichuan Basin belonged to the Yangtze platform, which developed over a rifted continental margin that initiated along the southeastern side of the Yangtze block at ∼800 Ma ( Condon et al., 2005 ). The lithology of the Deng-1 Formation is mainly dolomite without fungus and algae, that of the Deng-2 Formation is algae-rich dolomite with snowflake-shaped structures and microorganisms with no snowflake-shaped structures, that of the Deng-3 Formation is mainly mudstone and classics, and that of the Deng-4 Formation is mainly algal dolomite and grey-black dolomitic mudstone.
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Turning the Drill-Bit Seismic Signature into an Opportunity for Static and 4D Dynamic Reservoir Characterization
More LessAuthors Y. NassærSummaryThe drill-bit seismic signature can provide valuable geophysical data for static and 4D dynamic reservoir characterization. In a fast-track approach, the dynamic time warping of the raw field near-offset RVSP seismic traces stacked along the drilled well trajectory and those generated from the synthetic model enables near-real-time scans for velocity updates and hence help well positioning and decision-making during drilling operation. Besides, the findings of this qualitative approach can assist and further constrain the much more computationally expensive velocity model update workflow of FWI.
Extending the RTM migration of two overlapping 3D-RVSP seismic datasets, acquired within a time lapse vintage, into the time domain helps derive the production-induced 4D-RVSP time shifts and time strain signatures. The comparison of these findings with those derived from LoFS/PRM surface seismic demonstrated the valuable and cost-effective contribution of drill-bit seismic signature, RVSP, to 4D dynamic reservoir characterization.
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Pressure and Saturation Engineering Values from 4D PP and PS Seismic Data
More LessAuthors A. Tura, M. Held, J. Simmons, A. Kvilhaug and P.E. DhelieSummaryFor field development and drilling decisions, production assets and reservoir engineers require dynamic reservoir properties. Here we present a new method to estimate saturation (in fractions) and pressure (in bars) from time-lapse seismic data to provide to reservoir engineers. This new three-step method is demonstrated over the Edvard Grieg field in the North Sea. We can realize this method thanks accurate estimation of AVO parameters (P-impedance and S-impedance) from joint inversion of PP and PS ocean bottom data. The first step in our method is to estimate a stable set of axes identifying water saturation increase, gas saturation increase, pressure increase, and pressure decrease in the 4D AVO cross-plot domain. In the second step, using these axes, we convert every 4D P-impedance and S-impedance data point into 4D pseudo-saturation and pseudo-pressure data point using a projection method. In the third step, we use the rock physics relationships and reference values at key field location to map 4D changes in the field from impedances to actual saturation and pressure values. This allows us to obtain fieldwide dynamic values for water and gas saturation changes, and injection and production related pressure changes. These dynamic changes are interpreted over the field.
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Multiple Removal by Applying Zero Offset SRME-Strategy via Case Study from Tarim Basin
More LessSummaryThe multiples in seismic data cause distortion of target layer primary reflections and affect the accuracy of the final imaging, especially reducing the interpretation reliability. In this paper, we present a method for eliminating multiples from post-stack or migration seismic data, It is named the zero offset SRME because the source and receiver are located at the same position. The method is based on Surface-Related Multiple Elimination (SRME), which is derived from wave equation theory and is widely used in seismic marine data processing. Unlike conventional marine SRME methods, the zero offset SRME method does not rely on knowledge of subsurface structure or properties, and does not use seismic event properties to discriminate multiples and primaries. The method is successfully applied to seismic data in the desert area from Tarim basin and is shown to be effective in improving the accuracy of imaging. The zero offset SRME method has advantages over conventional SRME methods as it does not require harsh conditions, such as shot and receiver interpolation, signal-to-noise improvement, and amplitude balancing, as post-stack seismic data from desert areas has high signal-to-noise ratio and balanced amplitude. The authors use both synthetic and real data to demonstrate its effectiveness.
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Spatial Characterization of 3D Geological Structure based on the Improved Deep Network Configurations
More LessSummaryIn this paper, we propose to use a bidirectional long short-term memory network with an attention mechanism (BiLSTM-Attention) to describe the spatial structure of 3D complex thin sand bodies. The 3D geological model contains a thin layer of river channels and alluvial fans with specific geological implications. We conduct high-resolution impedance inversion tests based on the sparse spike inversion, geostatistics inversion and BiLSTM-Attention network, respectively. On the evaluation of the inversion results, in addition to the presentation of the inversion profiles, we also perform a comparative analysis of the planar spreading of the sand body. The accuracy and precision of different methods for spatial spreading and distribution range of complex 3D thin sand bodies are compared comprehensively. The test results demonstrate that our proposed technical scheme achieves better inversion effects in terms of both profile and slice comparisons. The distinction of sand superposition relationships and the description of spatial spreading are more accurately.
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Differences in the Morphology, Geochemistry, and Microbial Communities of Shallow-Water Fe–Mn Nodules with Water Depth
More LessSummaryFe-Mn nodules are present in not only deep-sea abyssal plain but also shallow-water environment. We studied the morphology, geochemistry and microbial communities of 424 Fe–Mn nodules collected from two different water depths on the continental shelf of the East Siberian Sea. Fe–Mn nodules collected from St58i (water depth, 73 m) were commonly yellow-brown with a tabular shape and smooth surface texture, whereas those collected from St52 (water depth, 150 m) were predominantly brownish-black with tabular, tubular, or ellipsoidal shapes and rough surface texture. Nodules collected from St58i had lower Mn content and higher Fe content than those from St52. Based on their Nd content and (Ce/Ce*)PASS, the nodules examined in this study may have formed through a diagenetic process, regardless of the water depth at which they were collected. Radiolarians, diatoms, and bacteria, as well as unknown microorganisms were found at both sites. Pennate diatoms were present at both water depths, whereas centric diatoms were present only in deeper waters. The observed morphological, geochemical, and biological characteristics of the nodules clearly differed between the two sites, indicating that the aqueous conditions and formation processes of nodules in the Arctic Ocean vary with water depth.
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An Optimized GPU Kernel for the 2+2+1 Method in Nonlinear Beamforming Technology
More LessAuthors Y. Sun, I. Silvestrov and A. BakulinSummaryThe challenge of the nonlinear beamforming (NLBF) technology is to efficiently estimate local traveltime operators from input data, which has to solve millions or even billions of highly nonlinear optimization problems per data gather. The 2+2+1 method is a popular solver for estimating local traveltime operators, but its efficiency is not ideal on the CPU platform. We recently proposed a 2+2+1 GPU algorithm to accelerate its calculation performance by exploiting GPU calculation, and this 2+2+1 GPU implementation used the global memory of GPU as the primary work space because the data aperture engaged in NLBF may be too large so that only the global memory is spacious enough to hold the required work data. However, since it is also common for NLBF to use a small data aperture, it inspires us to propose an optimized GPU kernel for the 2+2+1 method with the shared memory of GPU as the primary work space. Furthermore, we also adopt Horner’s method and a GPU-friendly data reduction method to further improve the efficiency of the 2+2+1 GPU kernel. Our test on one field dataset shows an obvious efficiency improvement from this optimized 2+2+1 GPU kernel over the previous one.
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Is Dense Shooting the Only Option to Improve 3D Seismic? The Mikro Teszt Embedded Acquisition Experiment
More LessAuthors M. Brown, M. Olsen, L. D’Ambrosia and B. WepferSummaryIn 2022, Hungarian Horizon Energy (HHE), a subsidiary of Aspect Holdings, LLC, acquired a 225+ square km modern 3D survey in the Pannonian Basin of Hungary. Reluctant to incur the additional cost and wait time for the “perfect” test, HHE embedded a Mikro Teszt (“micro test” in Hungarian) miniature 3D patch within the production acquisition patch of the new 3D survey, and extracted several real 3D surveys, which we processed independently to test several key shooting parameters. HHE completed the Mikro Teszt for an incremental cost of ∼1.5% of the total survey cost.
Our analysis enables HHE to roughly quantify the cost/benefit ratio of many of the key acquisition parameters (1 vs 6 phones/node, 1 vs 2 sweeps, sparse vs dense receivers) in terms of signal/noise ratio and frequency content. We found that the Mikro Teszt delivered far more believable conclusions than a typical pre-shoot field test, which force the operator to draw (potentially spurious) conclusions from a hasty comparison of raw shot records.
We discovered that a simple 6-phone/node receiver array yielded the best “bang-for-the-buck”, by significantly improving maximum recoverable frequency over standard single-sensor shooting, for ∼10% increase in acquisition cost.
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Identification of Carbonate Cave Reservoirs Using Wavelet Reconstruction and WRPCA Techniques
More LessSummaryCarbonate cave reservoirs, controlled by large strike-slip faults, hold significant potential for oil and gas exploration and development. Identifying these reservoirs is crucial but often challenging due to low SNR and the strong background reflection shielding in raw seismic data. To enhance seismic interpretation accuracy, we innovatively introduce the wavelet reconstruction and the weighted robust principal component analysis (WRPCA) techniques to eliminate strong background and noise interference. While the initial wavelet reconstruction can reduce part of the noise and background reflections, it falls short of fully separating reservoir reflections from interference signals. Consequently, the WRPCA technique is introduced post wavelet reconstruction to further achieve this goal. In comparison to traditional RPCA, WRPCA demonstrates higher accuracy and greater noise resistance, effectively isolating target reflections from background interference and noise. Subsequent attribute extraction and optimization are performed on the processed seismic data, with the instantaneous amplitude attribute chosen for cave reservoir identification. Applied to a basin in North China, these methods produce promising results, demonstrating their feasibility and validity in characterizing carbonate cave reservoirs.
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OBC Shallow Water De-Multiple Using Fresnel Diffraction Principle: a Case Study in Bohai Bay
More LessSummaryOBC seismic data in shallow water environments often have inaccurate seabed reflection information, so the SRME method is not effective in eliminating the shallow water multiples. This article uses a simple method to predict the shallow water multiples. According to the principle of Fresnel diffraction integration, the known seismic wave field is used to infer the shallow water multiples wave field. A simple algorithm is used in the t-x domain to achieve the shallow water multiples prediction and elimination. When the main frequency of seismic data decreases, it is proposed to eliminate only the second-order and higher-order shallow water multiples to avoid the loss of primary waves.The forward modeling and real data testing show that this method can effectively predict and eliminate the shallow water multiples.
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Least-Squares High Resolution Processing Method based on Iconology
More LessSummaryThe Least-squares migration can produce a high-quality migration images, but it is difficult to apply to the pre-processing stage due to the expensive computational cost. While the high-dimensional-space deblurring processing methods based on iconology are computationally efficient and can produce a high-resolution image, but have not been applied in the geophysics. How to combine the Least-squares migration theory with the deblurring technology of iconology is helpful to an efficient and high-resolution processing method. As we know, the migration image is the convolution of point spread function (PSF) and true reflection coefficient. The high-resolution processing method is actually an inverse problem of this forward problem. In this paper, a purely data-driven PSF extraction method is proposed based on the iconology. Then a high-dimensional space deconvolution algorithm is used to obtain high-resolution imaging results. The tests of data shows the proposed algorithm has the advantage of improving the resolution of geological bodies with different slope compared with the conventional high-resolution algorithms.
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Study on the Relationship between Hydraulic and Electrical Tortuosity of Digital Rocks
More LessSummaryRock hydraulic tortuosity is a crucial microscopic parameter to compute permeability and has been difficult to obtain hydraulic tortuosity. Many researchers use electrical tortuosity to replace it, which is due to the similar patterns of movement. However, a growing body of research proves that the two are not equal. However, there are no studies to confirm the specific differences between the two, especially for real rocks. In addition, there are no studies to explain the effect of tortuosity on permeability. To solve the above problems, we use algorithms to build digital rock models and use the finite element method to simulate the fluid and current passing through the rock. The hydraulic tortuosity and electrical tortuosity are computed based on the streamline distribution and current density distribution line. The results show that the difference between the two varies with the porosity. Our simulation results show an excellent quadratic function relationship. Finally, we use the LBM algorithm to compute the absolute permeability of the models that have the same porosity value and distribution law but different tortuosity to reveal the effect of tortuosity on it. The results show that the increase in tortuosity leads to a decrease in permeability.
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Mitigating Water Challenges in the Greater Burgan Field
More LessAuthors M. Jasem, O. Alzankawi, S. Al-Kandari, G. Perez, N. Rajabli, B. Saleh, A. Al-Fadhli and A. AlsamhanSummaryField on production since 75 years, and sharing method to mitigate water challenges increase and risk of losing production
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Conditioning Seismic Inversion to the Results of Forward Stratigraphic Modeling
More LessAuthors W. AlKawai and X. WangSummaryThis abstract shows a new workflow to improve constructing background model for seismic inversion in areas of spatially limited well control. The workflow uses results from forward stratigraphic modeling together with rock physics to condition the background model of seismic impedance. The advantage of the workflow is the ability to honor spatial trends of seismic impedance that are resulting from spatial heterogeneity of depositional facies. The workflow can improve seismic reservoir characterization in areas of spatially limited well control.
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Azimuthal Reflected P-Wave Imaging: Experiment and Field Application
More LessSummaryAzimuthal acoustic reflection imaging logging, which can measure the distance and azimuth of geological bodies beside the borehole within a range of tens of meters, is becoming an important technology for geophysical applications. Measurements for single-well acoustic reflection imaging in the model with a 1:1 reflection interface outside the borehole provide physical validation of this technique. In this paper, the analytical solution for the monopole reflection wavefield in the fluid-filled borehole is deduced by using the virtual source analogy. The simulation shows that the radiation wave from the nearby borehole is equivalent to the reflected wave from the reflector outside the borehole. On this basis, the experimental idea of using two parallel wells to achieve the verification experiment of single-well azimuthal reflected P-wave imaging is proposed. The experimental results show that the amplitude and arrival time of the azimuthal reflected P wave are sensitive to the azimuth of the reflector outside the borehole. This information can be used for precise positioning of geological anomalies outside the borehole. Under the guidance of theoretical simulations and experiments, the prototype of azimuthal reflected P-wave imaging logging tool was designed independently. Field tests were conducted, recording high signal-to-noise ratio azimuthal reflected P wave.
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