Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801101
E. Iversen, B. Ursin, M. V. Hoop
{"title":"Higher-order Dynamic Ray Tracing for Extrapolation of Traveltime and Geometrical Spreading","authors":"E. Iversen, B. Ursin, M. V. Hoop","doi":"10.3997/2214-4609.201801101","DOIUrl":"https://doi.org/10.3997/2214-4609.201801101","url":null,"abstract":"","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129644207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201800997
R. Laws, J. Hopperstad, E. Kragh, D. Halliday
Environmentally, marine seismic vibrators offer a safer way to emit acoustic energy into the earth. Even though they might produce a similar sound exposure level (SEL) to a corresponding airgun array, the SEL injury threshold for marine mammals is significantly higher for continuous sounds than it is for impulsive sounds. It is this reduced animal sensitivity, rather than the vibrator’s lower peak pressure, that gives the vibrator its environmental advantage over airguns for marine mammals. Geophysically, there has always been concern about the marine vibrator’s ability to generate enough energy, especially at the low frequencies. For all pulsating acoustic sources, there is an inherent reduction of output at low frequencies. It is indeed difficult to generate enough acoustic energy from a marine seismic vibrator array if the energy requirement is to match the spectrum of an airgun array. But airgun arrays typically produce an excess of energy. By configuring the sweep so as to emit only as much energy as is actually needed to produce the required image signal-to-noise ratio we can make marine vibrators viable.
{"title":"How Can We Emit Enough Energy From a Marine Seismic Vibrator?","authors":"R. Laws, J. Hopperstad, E. Kragh, D. Halliday","doi":"10.3997/2214-4609.201800997","DOIUrl":"https://doi.org/10.3997/2214-4609.201800997","url":null,"abstract":"Environmentally, marine seismic vibrators offer a safer way to emit acoustic energy into the earth. Even though they might produce a similar sound exposure level (SEL) to a corresponding airgun array, the SEL injury threshold for marine mammals is significantly higher for continuous sounds than it is for impulsive sounds. It is this reduced animal sensitivity, rather than the vibrator’s lower peak pressure, that gives the vibrator its environmental advantage over airguns for marine mammals.\u0000\u0000Geophysically, there has always been concern about the marine vibrator’s ability to generate enough energy, especially at the low frequencies. For all pulsating acoustic sources, there is an inherent reduction of output at low frequencies. \u0000\u0000It is indeed difficult to generate enough acoustic energy from a marine seismic vibrator array if the energy requirement is to match the spectrum of an airgun array. But airgun arrays typically produce an excess of energy. By configuring the sweep so as to emit only as much energy as is actually needed to produce the required image signal-to-noise ratio we can make marine vibrators viable.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129884085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801035
M. Kalita, V. Kazei, Yunseok Choi, T. Alkhalifah
Summary Full-waveform inversion (FWI) often attempts to resolve an ill-posed non-linear optimization problem in order to retrieve the unknown subsurface model from the seismic data. With model regularization, we alleviate the ill-posedness of FWI associated with salt bodies affected datasets by decoupling the minimization problem into two parts. We minimize the data misfit along with the total variation in the model, seeking an inverted model with sharp interfaces. In the second optimization, we penalize sharp velocity drops in the model, which is equivalent to computationally flooding of velocity field. Besides the minimal human intervention, our technique requires no information whatsoever of the top of the salt, which is required for conventional industrial salt flooding. Those features are demonstrated on a dataset corresponding to the BP 2004 model with frequencies less than 3 Hz muted to make the data more practical. The model is well retrieved if the same constant density acoustic code is used for preparing the observed data, which is still one of the most common FWI tests. However, our approach still allows us to reconstruct a reasonable depiction of the salt structure from data synthesized independently with a variable density model.
{"title":"Full-Waveform Inversion for Automated Salt Flooding","authors":"M. Kalita, V. Kazei, Yunseok Choi, T. Alkhalifah","doi":"10.3997/2214-4609.201801035","DOIUrl":"https://doi.org/10.3997/2214-4609.201801035","url":null,"abstract":"Summary Full-waveform inversion (FWI) often attempts to resolve an ill-posed non-linear optimization problem in order to retrieve the unknown subsurface model from the seismic data. With model regularization, we alleviate the ill-posedness of FWI associated with salt bodies affected datasets by decoupling the minimization problem into two parts. We minimize the data misfit along with the total variation in the model, seeking an inverted model with sharp interfaces. In the second optimization, we penalize sharp velocity drops in the model, which is equivalent to computationally flooding of velocity field. Besides the minimal human intervention, our technique requires no information whatsoever of the top of the salt, which is required for conventional industrial salt flooding. Those features are demonstrated on a dataset corresponding to the BP 2004 model with frequencies less than 3 Hz muted to make the data more practical. The model is well retrieved if the same constant density acoustic code is used for preparing the observed data, which is still one of the most common FWI tests. However, our approach still allows us to reconstruct a reasonable depiction of the salt structure from data synthesized independently with a variable density model.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130316100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801330
P. Zaradkiewicz, E. Eriksson, P. Christian, H. Klemm, P. Hickman
Summary Seabed subsidence caused by reservoir compaction is a common phenomenon occurring during oil and gas production. In the offshore environment it is monitored using GPS (Global Positioning System) receivers on surface installations such as production platforms. However, the area affected by seabed subsidence can extend away from this single point of measurement, especially when the reservoirs are produced using long horizontal wells. To fully map the subsiding area dedicated seabed surveys are required. In absence of dedicated time-lapse seabed surveys we decided to use bathymetry data recorded during 3D and 4D seismic surveys over several fields in the Danish sector of the North Sea. Due to limited accuracy and sparse spatial resolution such data are rarely used for seabed bathymetry and subsidence measurements. However, by developing a dedicated processing workflow it has been possible to significantly improve the estimated accuracy of the subsidence calculation to 0.3m. This extended abstract describes the data processing workflow, the results and their current utilization in geomechanics and reservoir management. It also discusses potential future utilization in other technical areas.
{"title":"Time-Lapse Bathymetry Processing for Seabed Subsidence Monitoring","authors":"P. Zaradkiewicz, E. Eriksson, P. Christian, H. Klemm, P. Hickman","doi":"10.3997/2214-4609.201801330","DOIUrl":"https://doi.org/10.3997/2214-4609.201801330","url":null,"abstract":"Summary Seabed subsidence caused by reservoir compaction is a common phenomenon occurring during oil and gas production. In the offshore environment it is monitored using GPS (Global Positioning System) receivers on surface installations such as production platforms. However, the area affected by seabed subsidence can extend away from this single point of measurement, especially when the reservoirs are produced using long horizontal wells. To fully map the subsiding area dedicated seabed surveys are required. In absence of dedicated time-lapse seabed surveys we decided to use bathymetry data recorded during 3D and 4D seismic surveys over several fields in the Danish sector of the North Sea. Due to limited accuracy and sparse spatial resolution such data are rarely used for seabed bathymetry and subsidence measurements. However, by developing a dedicated processing workflow it has been possible to significantly improve the estimated accuracy of the subsidence calculation to 0.3m. This extended abstract describes the data processing workflow, the results and their current utilization in geomechanics and reservoir management. It also discusses potential future utilization in other technical areas.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130533302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201800776
Y. Sun, H. Dong, J. Sun, L. Cui, X. Zeng
Sun et al. present an attempt to take the high resolution CT scanning technology in the application of quantitative characterization and characteristics analysis of micro pore structure in tight natural gas hydrate reservoir. The authors successfully apply the technology to samples selected and the technology is proved to be practicable.
{"title":"The Application of High Resolution CT Scanning Technology in Tight Natural Gas Hydrate Rock","authors":"Y. Sun, H. Dong, J. Sun, L. Cui, X. Zeng","doi":"10.3997/2214-4609.201800776","DOIUrl":"https://doi.org/10.3997/2214-4609.201800776","url":null,"abstract":"Sun et al. present an attempt to take the high resolution CT scanning technology in the application of quantitative characterization and characteristics analysis of micro pore structure in tight natural gas hydrate reservoir. The authors successfully apply the technology to samples selected and the technology is proved to be practicable.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126798649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801025
Yongyang Sun, B. Gurevich, M. Lebedev, S. Glubokovskikh, V. Mikhaltsevitch
Summary Quantifying the impact of pore fill on elastic properties of porous rocks is of ongoing interets in geophysics. Previous experiements show that the change of the solid pore fill can produce larger change in effective elastic properties of porous rocks than predicted by exisiting models. This effect may result from the heterogeneous stress distribution within the pore space due to the existence of stiff and soft pores. In this paper, we present a new solid substitution scheme based on the concept of a triple pore structure, including stiff, compliant and so-called intermediate pores. Comparison of the model predictions against ultrasonic measurements on an Octodecane-saturated sandstone reveal a reasonable fit for the bulk modulus but a small discrepancy for the shear modulus, performing more accurately than previous models. This discrepancy might be resulted from the instability of ultrasonic measurements at relative small confining pressure.
{"title":"A Simple Recipe for Estimating the Change in Elastic Properties of Porous Rocks with Solid Infill","authors":"Yongyang Sun, B. Gurevich, M. Lebedev, S. Glubokovskikh, V. Mikhaltsevitch","doi":"10.3997/2214-4609.201801025","DOIUrl":"https://doi.org/10.3997/2214-4609.201801025","url":null,"abstract":"Summary Quantifying the impact of pore fill on elastic properties of porous rocks is of ongoing interets in geophysics. Previous experiements show that the change of the solid pore fill can produce larger change in effective elastic properties of porous rocks than predicted by exisiting models. This effect may result from the heterogeneous stress distribution within the pore space due to the existence of stiff and soft pores. In this paper, we present a new solid substitution scheme based on the concept of a triple pore structure, including stiff, compliant and so-called intermediate pores. Comparison of the model predictions against ultrasonic measurements on an Octodecane-saturated sandstone reveal a reasonable fit for the bulk modulus but a small discrepancy for the shear modulus, performing more accurately than previous models. This discrepancy might be resulted from the instability of ultrasonic measurements at relative small confining pressure.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129341752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801061
P. Tillotson, D. Davies, L. Wang, M. Ball, A. Toomey, E. L’heureux
Summary Observations of seismic anisotropy in field seismic data are often used to infer fracture properties in the subsurface. To understand if anisotropic elastic parameters can be measured following extensive seismic processing and migration we created a field scale elastic finite difference model simulating a 4-component ocean bottom seismic dataset. The model was built with realistic geological sequences in the overburden and HTI reservoir compartments. Each HTI compartment had different fracture properties (e.g. fracture azimuth and density). Following industry standard methods for denoise and migration we ran post-migration azimuthal velocity and AVOA analysis. Our results find that azimuthal velocities are robust to seismic processing and we appear to be able to measure the input elastic model HTI δ parameter along with the fracture azimuth direction with a reasonable degree of accuracy. Measurements of AVOA are less successful in comparison. Phi azimuth angles compare fairly well with the input model, however the azimuthal anisotropic gradient term shows a poor correlation with the input model.
{"title":"From Anisotropic Elastic Tensors to Seismic Data and Back: Extraction of Azimuthal Anisotropy Parameters from a Field Sc","authors":"P. Tillotson, D. Davies, L. Wang, M. Ball, A. Toomey, E. L’heureux","doi":"10.3997/2214-4609.201801061","DOIUrl":"https://doi.org/10.3997/2214-4609.201801061","url":null,"abstract":"Summary Observations of seismic anisotropy in field seismic data are often used to infer fracture properties in the subsurface. To understand if anisotropic elastic parameters can be measured following extensive seismic processing and migration we created a field scale elastic finite difference model simulating a 4-component ocean bottom seismic dataset. The model was built with realistic geological sequences in the overburden and HTI reservoir compartments. Each HTI compartment had different fracture properties (e.g. fracture azimuth and density). Following industry standard methods for denoise and migration we ran post-migration azimuthal velocity and AVOA analysis. Our results find that azimuthal velocities are robust to seismic processing and we appear to be able to measure the input elastic model HTI δ parameter along with the fracture azimuth direction with a reasonable degree of accuracy. Measurements of AVOA are less successful in comparison. Phi azimuth angles compare fairly well with the input model, however the azimuthal anisotropic gradient term shows a poor correlation with the input model.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123900825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801285
L. Hong, G. Wen, X. Min
Summary Sulige gas field is a typical inefficient tight sandstone gas field, evident by its sophisticated geology, low-permeability, low-porosity, low-abundance and strong heterogeneity. It is their thin effective thickness and poor continuity that makes the prediction of reservoir extremely challenging. In this research, we took X area as an example to investigate the methodology of low-permeability sweet reservoir prediction, by using the seismic facies reservoir characterization technique. Based on fundamental rock physics, the relationship between elastic parameters and reservoir characteristics was established, then methodology of prestack elasticity parameter simulation is used to predict the effective reservoir. In addition, with the help of detailed characterization of small faults and the law of gas-water distribution, the main control factors of gas-water were identified. It was clear that gas content was better in the hidden fault zone. This study showed evident geological effect on the exploration and development of low-permeability thin reservoir in Sulige gas field.
{"title":"Characterization of Dense Gas Reservoirs and Investigation on Control Factors in the Reservoir","authors":"L. Hong, G. Wen, X. Min","doi":"10.3997/2214-4609.201801285","DOIUrl":"https://doi.org/10.3997/2214-4609.201801285","url":null,"abstract":"Summary Sulige gas field is a typical inefficient tight sandstone gas field, evident by its sophisticated geology, low-permeability, low-porosity, low-abundance and strong heterogeneity. It is their thin effective thickness and poor continuity that makes the prediction of reservoir extremely challenging. In this research, we took X area as an example to investigate the methodology of low-permeability sweet reservoir prediction, by using the seismic facies reservoir characterization technique. Based on fundamental rock physics, the relationship between elastic parameters and reservoir characteristics was established, then methodology of prestack elasticity parameter simulation is used to predict the effective reservoir. In addition, with the help of detailed characterization of small faults and the law of gas-water distribution, the main control factors of gas-water were identified. It was clear that gas content was better in the hidden fault zone. This study showed evident geological effect on the exploration and development of low-permeability thin reservoir in Sulige gas field.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123926155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801619
P. Dell’Aversana, B. Ciurlo, S. Colombo
Summary We discuss how Machine Learning (ML) can support the integration workflow of heterogeneous geophysical data sets in the process of exploration risk evaluation and/or in the process of field appraisal. Data set includes seismic, electromagnetic, gravity and borehole measurements. We combine sequential geophysical modelling and inversion with statistical and automatic classification approaches commonly used in the field of Machine Learning. We applied this “hybrid approach” to two multidisciplinary geophysical data sets recorded in different geological settings, obtaining encouraging results in both cases.
{"title":"Integrated Geophysics and Machine Learning for Risk Mitigation in Exploration Geosciences","authors":"P. Dell’Aversana, B. Ciurlo, S. Colombo","doi":"10.3997/2214-4609.201801619","DOIUrl":"https://doi.org/10.3997/2214-4609.201801619","url":null,"abstract":"Summary We discuss how Machine Learning (ML) can support the integration workflow of heterogeneous geophysical data sets in the process of exploration risk evaluation and/or in the process of field appraisal. Data set includes seismic, electromagnetic, gravity and borehole measurements. We combine sequential geophysical modelling and inversion with statistical and automatic classification approaches commonly used in the field of Machine Learning. We applied this “hybrid approach” to two multidisciplinary geophysical data sets recorded in different geological settings, obtaining encouraging results in both cases.","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124002676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-11DOI: 10.3997/2214-4609.201801460
J. Ebbing
{"title":"3D Stochastic Inversion of Airborne Gravity Gradient Data - Case Example over the Karasjok Greenstone Belt","authors":"J. Ebbing","doi":"10.3997/2214-4609.201801460","DOIUrl":"https://doi.org/10.3997/2214-4609.201801460","url":null,"abstract":"","PeriodicalId":325587,"journal":{"name":"80th EAGE Conference and Exhibition 2018","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124028428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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