Seismic Technology Research Articles

Progress of 3D seismic exploration technologies and oil and gas exploration and development performance in the loess tableland area of the Ordos Basin

Progress of 3D seismic exploration technologies and oil and gas exploration and development performance in the loess tableland area of the Ordos Basin

Technological Advances in Japan’s High-Rise Buildings

The architectural and structural analysis of selected high-rise buildings in Japan is presented in this paper. Tokyo, Osaka and Nagoya have the largest share in development of high-rise buildings. Those cities are very densely populated and moreover they are located in one of the most active seismic zones. The combination of these factors has resulted in the creation of sophisticated designs and innovative engineering solutions, especially in the field of design and construction of high-rise buildings. The foreign architectural studios (Jean Nouvel, Kohn Pedesen Associates, Skidmore, Owings & Merrill) which specialize in the designing of skyscrapers, played a major role in the development of technological ideas and architectural forms for such extraordinary engineering structures. Among the projects completed by them, there are examples of high-rise buildings that set precedents for future development. An essential aspect which influences the design of high-rise buildings is the necessity to take into consideration their dynamic reaction to earthquakes and counteracting wind vortices. The need to control motions of these buildings, induced by the force coming from earthquakes and wind, led to the development of various methods and devices for dissipating energy during such phenomena. Currently, Japan is a global leader in seismic technologies which safeguard seismic influence on high-rise structures. Due to these achievements the most modern skyscrapers in Japan are able to withstand earthquakes with a magnitude of over seven degrees at the Richter scale. Applied damping devices applied are of a passive type, which do not require additional power supply or active type which need the input of extra energy. In recent years also hybrid dampers were used, with an additional active element to improve the efficiency of passive damping.

Application of high-end seismic imaging technologies for field development in NWS Australia

The North West Shelf, situated in the north-west of Western Australia, is a world-renowned offshore hydrocarbon province with investments of more than A$200 billion to date. However, the quality of...

Resolving Structural Uncertainty using DAS VSP Survey in Central Australia

Borehole seismic technology provides an efficient way to image the subsurface in high-resolution, through 3D, Walkaway or Offset VSPs. Whilst acquisition time of the conventional VSP survey is less...

Lithology characterisation of the roof and floor of the Moranbah measures coal seam using post-stack and pre-stack seismic inversion

3D seismic technology has become a popular exploration and development tool among coal mining companies in Australia in the last ten years. Traditionally the main use of these seismic data is to in...

Reflected wave least squares reverse time migration with angle illumination compensation

High-quality seismic data imaging plays an important role in the lithological interpretation of subsurface structures. However, high-quality imaging remains a challenging task. Based on the linear inversion theory of reflected wave equations, this paper proposes reflected wave least squares reverse time migration with angle illumination compensation to better balance the amplitude of seismic imaging. We use the reflected wave migration equation to unify forward and backward propagation, which helps to obtain an image with correct phase and symmetric waveform. Under the assumption that the spectrum of seismic wavefield remains unchanged, the Poynting vector method is used to efficiently calculate the propagation direction of seismic waveform and seismic illumination in the angle domain. During iteration, angle-domain illumination is used as a preconditioner to compensate for the amplitude of the iterated gradient terms based on the angle value. In this manner, we can enhance the imaging energy of steeply inclined structures. To improve the stability of linear inversion, the spatial derivative of the image is used as a regularized constraint term. Numerical tests show that the proposed method can suppress imaging noise as well as improve resolution and amplitude fidelity of the images. Furthermore, the inversed result can be used to estimate underground reflectivity, which is important for the further development of seismic inversion technology.

Advanced seismic monitoring technologies for coal and ore mines

Advanced seismic monitoring technologies for coal and ore mines

Applying integrated seismic technology to complex foothill areas of foreland basins in China

Due to complicated near-surface conditions, including large elevation changes and complex geologic structures, accurate imaging of subsurface structures for hydrocarbon exploration in the foreland basins of western China has been challenging for many years. After decades of research and fieldwork, we developed an effective seismic exploration workflow that uses the latest technologies from acquisition to imaging. They include 3D high-density and wide-azimuth (WAZ) acquisition, 3D true-surface tilted transverse isotropy (TTI) anisotropic prestack depth migration, and dual-detachment structural modeling and interpretation. To further reduce uncertainty in velocity model building and improve imaging quality, our geologists, geophysicists, and reservoir engineers worked closely through the exploration cycle (seismic acquisition, processing, and interpretation). This exploration model has been used successfully in hydrocarbon exploration of many complex foothill areas in western China. Three-dimensional WAZ high-density seismic surveys have been conducted over 40,000 km2of the foreland basins, greatly improving the field seismic data quality. After application of 3D true-surface TTI anisotropic depth model building and imaging with integrated structural interpretation, new discoveries of hydrocarbon reservoirs have increased. The application of new technologies not only increased drilling success but also reduced depth well-tie errors between seismic data and wells.

Innovative Structural Solutions for Prefab Reinforced Concrete Hall-Type Buildings

Background:The anti-seismic design of prefab reinforced concrete buildings is usually carried out with a conventional ductility-based approach. This implies a remarkable plastic demand on columns, as well as damages to the connections of structural and non-structural members, for seismic events with comparable intensity to the basic design earthquake normative level.Objective:In view of this, a study was developed and aimed at extending to the field of new prefab reinforced concrete structures the application of advanced seismic protection strategies, capable of guaranteeing undamaged response up to the maximum considered earthquake normative level.Method:A benchmark building was designed as demonstrative case study for this purpose, in the three following hypotheses: (a) according to a traditional ductility-based approach; (b) by incorporating dissipative bracings, equipped with fluid viscous dampers; (c) by placing a seismic isolation system at the base, composed of a set of double curved surface sliders.Results:The results of the verification analyses show that the targeted performance for the design solutions b) and c) is obtained with sizes of columns and plinths notably smaller than those for the conventional design. This allows compensating the additional cost related to the incorporation of the protective devices, for the dissipative bracing system, and limiting additional costs below 25%, for the base isolation solution. At the same time, a supplemental benefit of the latter is represented by greater protection of contents and plants, as they are fully supported by the seismically isolated ground floor.Conclusion:The study highlights the advantages offered by the two advanced seismic protection technologies in an unusual field of application, guaranteeing an enhanced performance of structural and non-structural elements, as well as reduced member sizes, as compared to the traditional ductility-based design.

In pursuit of increased resolution while preserving amplitude fidelity

Recent advances in acquisition and processing technology are an enabler for improving the resolution of our seismic images. However, care must be taken to ensure that these imaging enhancements retain the amplitude fidelity necessary to allow for detailed Amplitude Variation with Offset/Direct Hydrocarbon Indicator (AVO/DHI) analysis, particularly in the marine deepwater setting. Acquisition, processing and interpretation all play important and interrelated roles in obtaining the maximum utility from the seismic data. In this paper we will discuss where resolution and data fidelity can be gained or lost, what factors primarily determine bandwidth recovery, and what decisions still need to be made in a somewhat subjective, target-oriented manner. Data from deepwater Guyana is used to demonstrate fundamental principles and the evolution of acquisition and processing workflows over the history of this project. Finally, we will suggest areas where additional improvements can be achieved in seismic field technologies, processing and interpretations workflows.

Geophysics Bright Spots

Volunteers are busy putting together the technical program for the SEG Annual Meeting in San Antonio. As members of the SEG Research Committee, Ray Abma and I are organizing the “Recent advances and the road ahead” special session. We invited several TLE special section editors to present hot topics. In addition, we invited a few authors of papers nominated by the editors of this column to present their cutting-edge research. I think it will be an interesting mix. The session will focus on seismic technology, and I wish we had more room for some of the great nonseismic innovative work. I am always impressed with the diversity and quality of the Geophysics papers nominated for this column, like the ones below.

The Study of 4D Converted-Wave Seismic Interpretation Methods for CO2 Sequestration

CCUS technology is currently the most effective way to slow greenhouse gas emissions. CO2 geological storage technology is the core of CCUS technology. Combining 4D seismic technology with CCUS (Carbon Capture, Utilization and Storage) technology is the most effective way to confirm security of CO2 sequestration in CO2 geological storage project. However, conventional 4D seismic method mainly study on time-lapse PP reflection information which could not separate fluid saturation and pressure. The potential of using PS wave to monitor CO2-EOR and security of CO2 sequestration has not been explored. Our study focuses on 4D PS-wave. In order to improve our understanding of converted wave in utilization during CO2-EOR and CO2 sequestration. We built two-layer based models in both porous and fracture mediums before and after CO2 injection, and combining with rock physics data and well log data, we got the change rules of elastic parameters of mix fluids changing with injecting pressure before and after CO2 injection. We analyze the changes of PS1 and PS2 AVA curves, and we studied the relationship between time-lapse seismic data with pore pressure and CO2 saturation, then we could confirm the influence of pore pressure and CO2 saturation on 4D multicomponent seismic data. And then, we combined 4D converted wave forward models and 4D PP wave forward models. We studied the effect of pore pressure and fluid saturation on the change of PP-wave reflection coefficients and PS-wave reflection coefficients separately. Combined with the results of fluid substations in different pore pressure and fluid saturation, we could explore the effect of pore pressure and fluid saturation on P-wave velocity, S-wave velocity and density separately. We could establish the relationship between change of PP-wave reflection coefficients and PSwave reflection coefficients and change of pore pressure and fluid saturation. Thus, we computed the change of pore pressure and fluid saturation with 4D PP and PS seismic data.

Overview of Investigation of Potential CO2 Storage Sites Offshore Japan

Japan CCS Co., Ltd. (hereinafter “JCCS”) has been conducting the investigation of potential CO2 storage sites in Japan undercontract to the Ministry of the Environment (hereinafter “MOE”) and Ministry of Economy, Trade and Industry (hereinafter“METI”) of Japan since 2014. We have been conducting a number of 2D/3D seismic surveys and geological interpretation at pre-selected areas in offshore Japan, in order to identify prospective sites from among these areas. Several candidate sites will be selected from these prospective sites, and exploratory wells will be drilled to confirm the presence of geological conditions necessary for storage. The drilling will be followed by the construction of a geological model and flow simulation. The final goal of the current scope of work is to recommend three potential sites for CO2 geological storage to MOE and METI by around 2021. The main selection criteria of a potential storage site are as follows: > The potential sites should be located in offshore areas > Capacity of each site is to store over 100 million tonnes of CO2 > There are no active faults close to the site > The existence of a CO2 emission source near the site is not taken into consideration > The method of CO2 transportation to the site is not taken into consideration > Producing oil and gas fields are excluded (site is not for EOR purpose) > There is no environmental protected area around the site In addition, a preferable condition is whether the site can be reached by directional drilling from onshore, as is the case for the Tomakomai CCS Demonstration Project. In this project, two directional CO2 injection wells were drilled with horizontal reach of over 3,000 meters, saving considerable construction cost as it was not necessary to bring in an offshore drilling rig, or to lay expensive subsea pipelines and related offshore facilities. The 2D/3D seismic survey conducted in the investigation of potential sites is the most effective method to delineate the geological features of the subsurface. 2D seismic surveys are conducted to grasp the regional geological features over a wide range such as 50 x 100 km, and if prospective structures for CO2 geological storage are identified, 3D seismic surveys over a smaller range (e.g., 10 x 10 km) will be executed to delineate the geological features more precisely. When necessary, we employ state-of-art seismic acquisition and processing technology utilized in the oil and gas industry to accomplish our objectives. In one of the 3D seismic surveys, we have conducted a seamless 3D seismic survey across the transition zone between shallow marine and onshore. As the possible presence of active faults was suspected in the transition zone, there was a need to collect data from the shallow marine continuously to the onshore area. Although the survey has taken time and effort, we were able to fill the gap in the existing seismic data between offshore and onshore with data of reasonable resolution utilizing an Ocean Bottom Cable (OBC). The geological interpretation found that the subsurface of the transition zone was a narrow synclinal valley along the current coastline with no active faults present, and therefore that it was possible to store CO2 in the offshore area as it was safely isolated from the populated onshore area. At another prospective site, we have conducted a 3D seismic survey utilizing broadband technology; the first application of this state-of-art technology in Japan. Because the target sandstone reservoirs in the survey area are composed of deep marine sediments such as turbidites and submarine fans, high-resolution 3D seismic data is required to differentiate the sandstone types. The high resolution data may be further utilized for special processing such as acoustic impedance (AI) inversion and amplitude versus offset (AVO) analysis which is help to evaluate rock properties in order to reduce geological risk. The high resolution near surface data acquired in broadband technology is also useful in identifying shallow gas hazards in the area. In BroadSeisTM(*), the broadband seismic technology we adopted, the slanted streamer cables are deployed deeper than conventional seismic surveys, mitigating the effects of sea surface swells and wave noises under rough sea conditions. As a result, we were able to reduce drastically the downtime due to rough weather during the survey period. (*: trademark of CGG) In summary, the application of state-of-art seismic acquisition technology in the investigation of potential CO2 storage sites is expected to reduce geological risk as well as contribute towards saving acquisition costs.

Application of pre-stack simultaneous inversion to predict gas-bearing dolomite reservoir: a case study from Sichuan Basin, China

Pre-stack simultaneous inversion is a seismic exploration technology which is widely applied to recognize lithology and detect oil and gas by analyzing the feature of amplitude variation versus offset (AVO). A gas-bearing reservoir can cause an obvious change in P-impedance and density. To effectively discriminate gas-bearing dolomite within Longwangmiao Fm. in Sichuan Basin of China, the pre-stack inversion method is employed by strict quality procedures. These procedures mainly include rock physics analysis, AVO modeling and pre-stack simultaneous inversion. Using the technology, P-impedance, S-impedance and density are obtained simultaneously. The distribution of gas-bearing dolomite is identified by P-impedance versus density cross-plotting from well data. The final prediction result indicates the existence of gas-bearing dolomite in the upper part of Longwangmiao Fm. in the study area, which is consistent with well data. Generally, pre-stack simultaneous inversion represents an effective method to predict gas-bearing dolomite reservoir and should be applicable in other study areas.

Successful infill drilling campaign using fit-for-purpose seismic technologies doubles oil production and extends field life at Lakshmi Field, Gulf of Cambay, western India

The offshore Lakshmi Field, located in the southern part of Cambay Basin in the CB/OS-2 block in western India, is a success story of transitioning from a plateauing gas field to an oil-producing asset. Hydrocarbons sourced from Hazira Shale at Lakshmi Field are trapped in inversion-related four-way dip closures. The reservoirs are within the Miocene-age Tarkeshwar and overlying Babaguru formations; both have excellent reservoir quality with porosity ranging from 25% to 30% and Darcy-scale permeability. During the initial exploration stage, presence of oil was established in the deeper lower Tarkeshwar sands. However, the full oil potential of the field was not realized in the early stage of development due to difficulty in characterizing laterally and vertically discontinuous thin sands. These sands are often not detected in conventional 3D seismic data due to severe attenuation-related masking by overlying thick gas sands. Given the uncertainty of the oil potential of the field, a revised look using advanced seismic technologies was undertaken to drive a new infill drilling campaign. Seismic reprocessing using Q-tomographic inversion was performed to address the gas-attenuation problem, resulting in an improved seismic image. The new seismic data enabled characterization of thin reservoir sands using analytical techniques such as spectral decomposition and amplitude-variation-with-offset (AVO) attribute analysis. An integrated reservoir-characterization approach using field analogs, interpretation within a sequence stratigraphic framework, concepts of seismic geomorphology, and quantitative seismic analysis helped identify optimal areas of the sand fairway for infill well placement. Several infill wells have since been drilled that encountered good pay zones, validating the integrated approach. This successful campaign doubled oil production at Lakshmi and extended the field life by increasing reserves.

Understanding basement fracture architecture in Padra Field, South Cambay Basin, India, through full-azimuth imaging

Detection and characterization of fractures in reservoirs is of great importance for maximizing hydrocarbon productivity and recovery efficiency. Fractures play an important role in the producibility of unconventional reservoirs such as basement reservoirs. Basement reservoirs are typically found within metamorphic and igneous rock underlying a sedimentary basin, where faulting and tectonic uplift has led to creation of a fracture network. For fracture characterization, integration of information from seismic and nonseismic data such as cores and/or formation microimaging (FMI) logs is essential. Various seismic attributes such as coherency and curvature that are derived from reflection seismic data have been used for more than a decade to detect faults and fractures. In advanced seismic fracture detection technology, automatic fault extraction (AFE) from diffraction seismic data (discontinuity volume) more effectively detects finer scale features in seismic data. We demonstrate the utility of this methodology with an application to seismic data from the Padra Field, South Cambay Basin, India, where the basaltic Deccan Trap forms the basement, and hydrocarbons are produced from basement fractures. Diffraction imaging was applied during processing of the full-azimuth 3D-3C seismic data that cover this field. Using wavefield decomposition in the subsurface local angle domain, separate reflection (specular) and diffraction data volumes were produced. The high-resolution specular stack data imaged a prominent reflector well below the trap top, which is not visible in conventional seismic reflection data. Diffraction stack data also provided higher resolution fault definition and enhanced imaging of spatially consistent geological discontinuities. Subsequent application of the AFE technique to diffraction-imaged data yielded sharp and crisp definition of faults and fractures. We also performed velocity variation with azimuth analysis of 3D angle-azimuth reflection gathers to generate a fracture orientation map. Both sets of results were validated by fractures detected in FMI logs from wells in the field.

Seismic Design and Evaluation Methods for Small-to-Medium Span Highway Girder Bridges Based on Machine Learning and Earthquake Damage Experience

This study summarized the application field of machine learning to explore the basic seismic thinking of machine learning methods used for bridges. The development and actuality of bridge seismic analysis theories and technology were briefly reviewed, particularly in relation to the field of civil engineering. This study introduced the concept of machine learning, summarized its key factors and current software platforms, and illustrated the common methods and representative algorithms of machine learning using simple examples. First, the normal types of simply supported and continuous girder bridges, which are used for highway bridges with small and medium spans in China, were summarized. The earthquake damage phenomena had been observed for bridge types during the Wenchuan earthquake. Data from these phenomena were assessed, including the damage grade divisions of piers, bearings, shear keys, and abutments. Second, a series of seismic performance tests had been conducted by international and domestic academics for bearings, shear keys, piers, and abutments. These tests were summarized in this study to obtain the constitutive relationships for seismic analysis and determine the seismic design parameters of bridge components (including foundations). Finally, an overall analysis methodology based on machine learning was introduced into the bridge seismic analysis. This methodology explained that machine learning for bridge seismic tasks had two aspects. The first was the collection of considerable bridge design data and set up data sets, and the second was data reduction, including raw data processing and debugging or developing a reasonable machine learning algorithm model. This study also discussed the shortcomings of existing performance-based probabilistic seismic design and evaluation methods that are currently used in analyzing bridges in China. Results indicated the potential future major concerns for bridge seismic analysis technology. The establishment of computational simulations based on artificial intelligence method was also recommended. In addition, the mutual integration between disciplines and mutual communication among different professionals were advocated in this study.

Proposed Design Philosophy for Seismic-Resistant Buildings

Modern seismic design and technologies have undergone tremendous developments. In modern design codes, building structures subjected to high earthquake loads are allowed to experience plastic deformations without collapsing, and the design is permitted up to the ultimate strength. According to comparative results in Japan, the number of humans injured due to earthquakes is higher than the number of deaths/missing. Likewise, the number of residential buildings that collapsed are less than the partially damaged buildings. This outcome implies that residential buildings designed based on the revised seismic standards have good earthquake resistances. It also infers that the human deaths/injury casualties were not a result of the collapsed the structure, but due to the strong vibrations originated from the earthquake, yielding in the collapse of non-structural elements such as ceilings and bookshelves. This paper presents a proposed design philosophy that attempts to implement the effect of earthquakes to non-fatal human casualties

Nonlinear joint PP-PS AVO inversion based on improved Bayesian inference and LSSVM

Multiwave seismic technology promotes the application of joint PP-PS amplitude versus offset (AVO) inversion; however conventional joint PP-PS AVO inversioan is linear based on approximations of the Zoeppritz equations for multiple iterations. Therefore the inversion results of P-wave, S-wave velocity and density exhibit low precision in the faroffset; thus, the joint PP-PS AVO inversion is nonlinear. Herein, we propose a nonlinear joint inversion method based on exact Zoeppritz equations that combines improved Bayesian inference and a least squares support vector machine (LSSVM) to solve the nonlinear inversion problem. The initial parameters of Bayesian inference are optimized via particle swarm optimization (PSO). In improved Bayesian inference, the optimal parameter of the LSSVM is obtained by maximizing the posterior probability of the hyperparameters, thus improving the learning and generalization abilities of LSSVM. Then, an optimal nonlinear LSSVM model that defines the relationship between seismic reflection amplitude and elastic parameters is established to improve the precision of the joint PP-PS AVO inversion. Further, the nonlinear problem of joint inversion can be solved through a single training of the nonlinear inversion model. The results of the synthetic data suggest that the precision of the estimated parameters is higher than that obtained via Bayesian linear inversion with PP-wave data and via approximations of the Zoeppritz equations. In addition, results using synthetic data with added noise show that the proposed method has superior anti-noising properties. Real-world application shows the feasibility and superiority of the proposed method, as compared with Bayesian linear inversion.

Seismic exploration technology development and its outlook

Seismic exploration technology development and its outlook