Electromagnetic traveltime tomography: Application for reservoir characterization in the Lost Hills oil field, California

Geophysics ◽  
2005 ◽  
Vol 70 (3) ◽  
pp. G51-G58 ◽  
Author(s):  
Tae Jong Lee ◽  
Toshihiro Uchida
Keyword(s):  
Reservoir Characterization ◽  
Fresnel Zone ◽  
Region Of Interest ◽  
Oil Field ◽  
Data Sets ◽  
Traveltime Tomography ◽  
Conductivity Structure ◽  
Before And After ◽  
Conductivity Image ◽  
Induction Logs

Electromagnetic (EM) traveltime tomography has been applied for reservoir characterization at the Lost Hills oil field, California. Four data sets at frequencies of 24, 90, 370, and 1000 Hz were obtained along a pair of monitoring boreholes located 80.5 m apart. Traveltime information was first extracted from these EM data sets using a wavefield transform with a ray series approximation. The conductivity contrast of each layer is no greater than two in the region of interest, so the first arrivals can be estimated within 5% error by the approximate scheme. A nonlinear traveltime tomography algorithm adopting a Fresnel zone concept was then applied to obtain the conductivity model between the boreholes. The resultant conductivity image represents the conductivity structure between the boreholes. This image is consistent with the results of both a finite-difference inversion and the induction log obtained prior to waterflooding. Comparing the two conductivity images with the induction logs, we observe major differences in the fracture-dominant resistive reservoir layer, which may have been caused by changes in reservoir condition before and after waterflooding.

Resolution of slowness and reflectors in crosswell tomography with transmission and reflection traveltimes

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. VE321-VE335 ◽  
Author(s):  
Kenneth P. Bube ◽  
Robert T. Langan
Keyword(s):  
Field Experiments ◽  
Oil Field ◽  
Data Sets ◽  
Traveltime Tomography ◽  
Velocity Models ◽  
West Texas ◽  
Well Spacing ◽  
High Level ◽  
Transmission And Reflection

We sometimes encounter situations in seismic imaging in which knowing the position of key reflectors between wells would be very useful. In many crosswell data sets, both transmission and reflection traveltimes for selected reflectors can be picked. We investigated the possibility that transmission-plus-reflection crosswell traveltime tomography can determine the position of these reflectors with a high level of accuracy, thereby providing an independent way of verifying (and perhaps improving) the position of these reflectors obtained from crosswell reflection imaging. We studied the effect of combining reflection traveltimes for selected reflectors with transmission traveltimes on the resolution of the interwell slowness field and depth determination of selected reflectors. We found that theoretically, the position of reflectors is determined uniquely from transmission and reflection traveltimes in a linearized continuum formulation ofcrosswell tomography. We also computed diagonal elements of the resolu-tion matrix for two crosswell geometries based on field experiments conducted in a west Texas oil field to see what effect noise has on the accuracy of our determination of reflector depths. These computational results indicate that reflector positions are indeed very well determined for these geometries, with expected errors of [Formula: see text] of the well spacing when noise in traveltimes is [Formula: see text]. Because reflector-position parameters are so well determined, including reflection traveltimes does not degrade the resolution of the slowness field as a result of introducing additional reflector-depth parameters. Actually, the resolution of the slowness field, particularly near reflectors, improves by including reflection traveltimes, in spite of the fact that we must solve for these additional depth parameters. The improvement in slowness resolution should provide velocity models that can yield more accurate reflection images.

scholarly journals Observation evidences of atmospheric Gravity Waves induced by seismic activity from analysis of subionospheric LF signal spectra

2007 ◽  
Vol 7 (5) ◽  
pp. 625-628 ◽  
Author(s):  
A. Rozhnoi ◽  
M. Solovieva ◽  
O. Molchanov ◽  
P.-F. Biagi ◽  
M. Hayakawa
Keyword(s):  
Gravity Waves ◽  
Fresnel Zone ◽  
Signal Amplitude ◽  
Magnetic Storms ◽  
Frequency Range ◽  
Atmospheric Gravity Waves ◽  
Period Range ◽  
Before And After ◽  
Atmospheric Gravity ◽  
Large Earthquakes

Abstract. We analyze variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms. After 20 s averaging, the frequency range of the analysis is 0.28–15 mHz that corresponds to the period range from 1 to 60 min. Changes in spectra of the LF signal perturbations are found several days before and after three large earthquakes, which happened in November 2004 (M=7.1), August 2005 (M=7.2) and November 2006 (M=8.2) inside the Fresnel zone of the Japan-Kamchatka wavepath. Comparing the perturbed and background spectra we have found the evident increase in spectral range 10–25 min that is in the compliance with theoretical estimations on lithosphere-ionosphere coupling by the Atmospheric Gravity Waves (T>6 min). Similar changes are not found for the periods of magnetic storms.

Digital Workflow to Enhance Reservoir Management Strategies for A Complex Oil Field Through Real Time and Advanced Engineering Monitoring Solution

2021 ◽  
Author(s):  
Julieta Alvarez ◽  
Oswaldo Espinola ◽  
Luis Rodrigo Diaz ◽  
Lilith Cruces
Keyword(s):  
Real Time ◽  
Reservoir Characterization ◽  
Management Strategies ◽  
Reservoir Management ◽  
Gas Production ◽  
Oil Field ◽  
Oil Reservoirs ◽  
Production Operation ◽  
Digital Workflow ◽  
Operational Decisions

Abstract Increase recovery from mature oil reservoirs requires the definition of enhanced reservoir management strategies, involving the implementation of advanced methodologies and technologies in the field's operation. This paper presents a digital workflow enabling the integration of commonly isolated elements such as: gauges, flowmeters, inflow control devices; analysis methods and data, used to improve scientific understanding of subsurface flow dynamics and determine improved operational decisions that support field's reservoir management strategy. It also supports evaluation of reservoir extent, hydraulic communication, artificial lift impact in the near-wellbore zone and reservoir response to injected fluids and coning phenomenon. This latest is used as an example to demonstrate the applicability of this workflow to improve and support operational decisions, minimizing water and gas production due to coning, that usually results in increasing production operation costs and it has a direct impact decreasing reservoir energy in mature saturated oil reservoirs. This innovative workflow consists on the continuous interpretation of data from downhole gauges, referred in this paper as data-driven; as well as analytical and numerical simulation methodologies using real-time raw data as an input, referred in this paper as model-driven, not commonly used to analyze near wellbore subsurface phenomena like coning and its impact in surface operation. The resulting analyses are displayed through an extensive visualization tool that provides instant insight to reservoir characterization and productivity groups, improving well and reservoir performance prediction capabilities for complex reservoirs such as mature saturated reservoirs with an associated aquifer, where undesired water and gas production is a continuous challenge that incorporates unexpected operational expenses.

Direct shear-wave seismic survey in Sanhu area, Qaidam Basin, west China

2022 ◽  
Vol 41 (1) ◽  
pp. 47-53
Author(s):  
Zhiwen Deng ◽  
Rui Zhang ◽  
Liang Gou ◽  
Shaohua Zhang ◽  
Yuanyuan Yue ◽  
...  
Keyword(s):  
Shear Wave ◽  
Reservoir Characterization ◽  
Qaidam Basin ◽  
P Wave ◽  
Data Sets ◽  
Direct Shear ◽  
Subsurface Structure ◽  
S Wave ◽  
West China ◽  
Wave Data

The formation containing shallow gas clouds poses a major challenge for conventional P-wave seismic surveys in the Sanhu area, Qaidam Basin, west China, as it dramatically attenuates seismic P-waves, resulting in high uncertainty in the subsurface structure and complexity in reservoir characterization. To address this issue, we proposed a workflow of direct shear-wave seismic (S-S) surveys. This is because the shear wave is not significantly affected by the pore fluid. Our workflow includes acquisition, processing, and interpretation in calibration with conventional P-wave seismic data to obtain improved subsurface structure images and reservoir characterization. To procure a good S-wave seismic image, several key techniques were applied: (1) a newly developed S-wave vibrator, one of the most powerful such vibrators in the world, was used to send a strong S-wave into the subsurface; (2) the acquired 9C S-S data sets initially were rotated into SH-SH and SV-SV components and subsequently were rotated into fast and slow S-wave components; and (3) a surface-wave inversion technique was applied to obtain the near-surface shear-wave velocity, used for static correction. As expected, the S-wave data were not affected by the gas clouds. This allowed us to map the subsurface structures with stronger confidence than with the P-wave data. Such S-wave data materialize into similar frequency spectra as P-wave data with a better signal-to-noise ratio. Seismic attributes were also applied to the S-wave data sets. This resulted in clearly visible geologic features that were invisible in the P-wave data.

Northern Hemisphere Glaciation, African Climate and Evolution

2021 ◽  
Author(s):  
Martin H. Trauth ◽  
Asfawossen Asrat ◽  
Nadine Berner ◽  
Faysal Bibi ◽  
Verena Foerster ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Species Turnover ◽  
Abrupt Onset ◽  
Data Sets ◽  
Scientific Idea ◽  
Gradual Process ◽  
Before And After ◽  
History Of ◽  
Change Point Models ◽  
Original Interpretation

<p>The hypothesis of a connection between the onset (or intensification) of Northern Hemisphere Glaciation (NHG), the stepwise increase in African aridity (and climate variability) and an important mammalian (including hominin) species turnover is a textbook example of the initiation of a scientific idea and its propagation in science. It is, however, also an example of the persistent popularity of a hypothesis despite mounting evidence against it. The first part of our work analyzes of the history of the scientific idea by seeking its roots, including coincidental meetings and exchanges between of scientists, at project meetings, conferences and workshops. The consequences of this idea are examined and its influence on subsequent scientific investigations both before and after it has been falsified. In the second part of our investigation, we examine why the idea that the high latitudes have a major control on the climate of the low latitudes and thus early human evolution persists. For this purpose, an attempt is made to understand the original interpretation of the data, with special consideration of the composition of the scientific team and their scientific backgrounds and persuasions. Some of the key records in support of the hypothesis of a step-wise transition will be statistically re-analyzed by fitting change-point models to the time series to determine the midpoint and duration of the transition – in case such a transition is found in the data. A critical review of key publications in support of such a connection and a statistical re-analysis of key data sets leads to three conclusions: (1) Northern Hemisphere Glaciation is a gradual process between ~3.5–2.5 Ma, not an abrupt onset, either at ~2.5 Ma, nor at ~2.8 Ma, or any other time in the Late Cenozoic Era, (2) the trend towards greater aridity in Africa during this period was also gradual, not stepwise in the sense of a consistent transition of a duration of ≤0.2 Ma, and (3) accordingly, a step-wise change in environmental conditions cannot be used to explain an important mammalian (including hominin) species turnover.</p>

Abstract P062: Ten Weeks of Daily Consumption of Common Fructose Containing Sugars Does Not Increase Liver Fat Content

Circulation ◽  
2013 ◽  
Vol 127 (suppl_12) ◽  
Author(s):  
Stephen Bravo ◽  
Joshua Lowndes ◽  
Zhiping Yu ◽  
James Rippe
Keyword(s):  
Region Of Interest ◽  
Subsequent Development ◽  
Fat Content ◽  
Normal Diet ◽  
Liver Fat ◽  
Hepatic Veins ◽  
Ct Scanner ◽  
Daily Consumption ◽  
Liver Fat Content ◽  
Before And After

Purpose: Evaluate the effect of addition of commonly consumed fructose containing sugars to the usual diet on liver fat content. Background: Fructose induced triglyceride synthesis has been argued to be augmented when accompanied by glucose. As the most common sources of fructose, high fructose corn syrup HFCS) and sucrose, also contain glucose such a response would be particularly detrimental to metabolic health due to the known role of excess fat in the liver in the induction of abnormalities in glucose homeostasis, insulin resistance and the subsequent development of type II diabetes. Methods: For ten weeks, sixty-eight individuals (42.16 ± 11.66 years) consumed low-fat milk sweetened with either HFCS or sucrose such that the added sugar matched the 25th, 50th and 90th percentile population consumption levels of fructose. Fat content of the liver was obtained before and after the ten week intervention. Imaging was performed on a Philips 64-slice CT scanner. Region of interest measurements in the four sectors of the liver delineated by the hepatic veins were obtained in all patients, and converted to hepatocellular fat content percentages. Fat content of the liver remained unchanged (13.32 ±10.49 vs 13.32 ± 10.75%, p > 0.05). Group assignment did not affect the result interaction p > 0.05). Conclusions: These data suggest that ectopic fat storage in the liver is not promoted when fructose is consumed as part of a normal diet, even in amounts as high as the 90th percentile consumption level.

Integrated reservoir characterization: Beyond tomography

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 354-364 ◽  
Author(s):  
Larry Lines ◽  
Henry Tan ◽  
Sven Treitel ◽  
John Beck ◽  
Richard Chambers ◽  
...  
Keyword(s):  
History Matching ◽  
Preferential Flow ◽  
Reservoir Characterization ◽  
Seismic Anisotropy ◽  
Flow Direction ◽  
Geophysical Methods ◽  
Reservoir Properties ◽  
Traveltime Tomography ◽  
Sonic Log ◽  
Primary Water

In 1992, there was a collaborative effort in reservoir geophysics involving Amoco, Conoco, Schlumberger, and Stanford University in an attempt to delineate variations in reservoir properties of the Grayburg unit in a West Texas [Formula: see text] pilot at North Cowden Field. Our objective was to go beyond traveltime tomography in characterizing reservoir heterogeneity and flow anisotropy. This effort involved a comprehensive set of measurements to do traveltime tomography, to image reflectors, to analyze channel waves for reservoir continuity, to study shear‐wave splitting for borehole stress‐pattern estimation, and to do seismic anisotropy analysis. All these studies were combined with 3-D surface seismic data and with sonic log interpretation. The results are to be validated in the future with cores and engineering data by history matching of primary, water, and [Formula: see text] injection performance. The implementation of these procedures should provide critical information on reservoir heterogeneities and preferential flow direction. Geophysical methods generally indicated a continuous reservoir zone between wells.

scholarly journals MIXTURE: an improved algorithm for immune tumor microenvironment estimation based on gene expression data

2019 ◽  
Author(s):  
Elmer A. Fernández ◽  
Yamil D. Mahmoud ◽  
Florencia Veigas ◽  
Darío Rocha ◽  
Mónica Balzarini ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Immune Cell ◽  
Therapy Response ◽  
Cell Types ◽  
Gene Signature ◽  
Response To Therapy ◽  
Support Vector ◽  
Data Sets ◽  
Cell Type ◽  
Before And After

AbstractRNA sequencing has proved to be an efficient high-throughput technique to robustly characterize the presence and quantity of RNA in tumor biopsies at a given time. Importantly, it can be used to computationally estimate the composition of the tumor immune infiltrate and to infer the immunological phenotypes of those cells. Given the significant impact of anti-cancer immunotherapies and the role of the associated immune tumor microenvironment (ITME) on its prognosis and therapy response, the estimation of the immune cell-type content in the tumor is crucial for designing effective strategies to understand and treat cancer. Current digital estimation of the ITME cell mixture content can be performed using different analytical tools. However, current methods tend to over-estimate the number of cell-types present in the sample, thus under-estimating true proportions, biasing the results. We developed MIXTURE, a noise-constrained recursive feature selection for support vector regression that overcomes such limitations. MIXTURE deconvolutes cell-type proportions of bulk tumor samples for both RNA microarray or RNA-Seq platforms from a leukocyte validated gene signature. We evaluated MIXTURE over simulated and benchmark data sets. It overcomes competitive methods in terms of accuracy on the true number of present cell-types and proportions estimates with increased robustness to estimation bias. It also shows superior robustness to collinearity problems. Finally, we investigated the human immune microenvironment of breast cancer, head and neck squamous cell carcinoma, and melanoma biopsies before and after anti-PD-1 immunotherapy treatment revealing associations to response to therapy which have not seen by previous methods.

scholarly journals Estimation of Oil-Water Contact Level Using Different Approaches: A Case Study for an Iraqi Carbonate Reservoir

2020 ◽  
Vol 10 (2) ◽  
pp. 95-113
Author(s):  
Wisam I. Al-Rubaye ◽  
Dhiaa S. Ghanem ◽  
Hussein Mohammed Kh ◽  
Hayder Abdulzahra ◽  
Ali M. Saleem ◽  
...  
Keyword(s):  
Capillary Pressure ◽  
Reservoir Characterization ◽  
Petroleum Industry ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Accurate Estimation ◽  
Water Contact ◽  
Oil Water ◽  
Original Oil In Place ◽  
Drainage Data

In petroleum industry, an accurate description and estimation of the Oil-Water Contact(OWC) is very important in quantifying the resources (i.e. original oil in place (OIIP)), andoptimizing production techniques, rates and overall management of the reservoir. Thus,OWC accurate estimation is crucial step for optimum reservoir characterization andexploration. This paper presents a comparison of three different methods (i.e. open holewell logging, MDT test and capillary pressure drainage data) to determine the oil watercontact of a carbonate reservoir (Main Mishrif) in an Iraqi oil field "BG”. A total of threewells from "BG" oil field were evaluated by using interactive petrophysics software "IPv3.6". The results show that using the well logging interpretations leads to predict OWCdepth of -3881 mssl. However, it shows variance in the estimated depth (WELL X; -3939,WELL Y; -3844, WELL Z; -3860) mssl, which is considered as an acceptable variationrange due to the fact that OWC height level in reality is not constant and its elevation isusually changed laterally due to the complicated heterogeneity nature of the reservoirs.Furthermore, the results indicate that the MDT test can predict a depth of OWC at -3889mssl, while the capillary drainage data results in a OWC depth of -3879 mssl. The properMDT data and SCAL data are necessary to reduce the uncertainty in the estimationprocess. Accordingly, the best approach for estimating OWC is the combination of MDTand capillary pressure due to the field data obtained are more reliable than open hole welllogs with many measurement uncertainties due to the fact of frequent borehole conditions.

scholarly journals Increasing Waterflood Reserves in the Wilmington Oil Field Through Improved Reservoir Characterization and Reservoir Management

10.2172/1464 ◽  
1998 ◽  
Author(s):  
Chris Phillips ◽  
Dan Moos ◽  
Don Clarke ◽  
John Nguyen ◽  
Kwasi Tagbor ◽  
...  
Keyword(s):  
Reservoir Characterization ◽  
Reservoir Management ◽  
Oil Field
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