Intra- and Inter-Facies Variability of Multi-Physics Data in Carbonates. New Insights from Database of ALBION R&D Project
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Abstract In carbonates, the geological facies is a key driver for populating reservoir models with petrophysical properties. Conventionnal core analysis mainly contributes to establish relationships between facies, petrophysics and geophysics. However, populating gridblocks reservoir models with petrophysics requires parsimonious facies classifications and effective relationships at larger scales that field studies rarely investigate. Studying outcrop analogues helps filling the gap between lab measurements and effective upscaled properties of models, and considerably improves the modelling workflows. The ALBION R&D project developed an innovative framework for multi-physics and multi-scales characterization of Barremian-Aptian carbonates from south-eastern France. These outcropping rudist-rich limestones constitute an analogue of Middle-East reservoirs. Petrophysical and geophysical properties were measured on plugs from cores and outcrops but also at larger scales thanks to original experiments on cores, in and between boreholes. Indeed the analogue includes several experimental areas, where hydraulic tests in sealed wells sections and tomographies between very close boreholes allowed investigating petrophysical and geophysical rock properties at intermediate decimetric to decametric scales. Thanks to the resulting database, this paper aims quantifying the variability of multi-physics data (e.g. porosity, permeability, and P-wave velocity) at different scales in regards of an updated and unified facies classification. The latter is only based on sedimentary origin and fabrics. Other available properties affecting petrophysics are used to cluster facies associations in sub-classes. Consequently the facies classification does not allow discriminating the distributions of porosity, permeability, nor p-wave velocity. For the rudist facies, that is the most sampled, texture subclasses do not help this work. Reversely, the place of sampling, that is likely a proxy of diagenesis and age, cluster the petrophysical distributions. The results remind us that a proper facies definition should consider both sedimentary origin, fabrics, texture, diagenesis and tectonics. They also point out the relative importance of each characteristics in regards of the scale of interest and the difficulty to infer upscaled relationships between rock properties from CCAL because the representative elementary volume of carbonates is usually higher than the plug and even the core volumes.Keywords:
Petrophysics
Outcrop
Careful petrographic examination of sidewall cores from Acacus sands, combined with routine core analysis, XRD and SEM data allowed for identification of 5 discrete rock families. Integration of the petrographic and wireline data, particularly NMR (CMR) data, enabled the identification of the 3 principle reservoir rocks 80+% of the time. Starting at the pore scale and discriminating discrete petrophysical Rock Types with unique petrophysical properties yields a much more robust characterization of the reservoir than can be obtained by conventional evaluation techniques. The integrated approach should reduce logging costs by enhancing the ability to identify rock types capable of storing and producing fluids and through the generation of more accurate fluid saturation profiles. Distinction of Rock Types permits more coherent interpretation of porosity-permeability, capillary pressure and electrical properties data measured in the lab. Applying these data in log analysis allows for better saturation and net pay calculations. Finally, the integration of rock types with depositional environments ultimately leads to better and more meaningful reservoir mapping which can be used to better locate future wells.
Petrophysics
Wireline
Saturation (graph theory)
Capillary pressure
Characterization
Igneous petrology
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Petrophysical evaluation of well log data is essential for the exploration and evaluation of hydrocarbon-bearing formations. Moreover, there are no standard criteria to implement cut-offs on petrophysical properties as a direction for economic decisions. In the present work, a petrophysical evaluation of well logging data from four wells in a mature oil field is performed to identify formation quality as a potential for hosting mature hydrocarbons reservoirs. Full consideration of cut-off values was taken into account. The cut-offs were estimated from well-recognized petrophysical relationships for permeability as a function of porosity, water saturation, and shale content. Results verification and calibration were also made based on laboratory measurements of petrophysical properties obtained from available core plugs in order to minimize uncertainty. Lithology analysis and characteristics revealed that the target formation is mainly sand and shale sequences. Results from well logs were in agreement with results obtained from core data. Formation effective porosity varies from 16 to 26% in all wells. A wide range of variations is observed in water saturation ranging from 28 to 57% and permeability ranging from 20 to 3300 mD. This is in good agreement with other measurements and well log analysis that show the mature formation remains to be a good hydrocarbon reservoir with significant potential.
Petrophysics
Lithology
Formation evaluation
Saturation (graph theory)
Water saturation
Effective porosity
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Borehole geophysics have been around since the late 1800's when U.S.G.S. personnel used a wireline to take temperature measurements in a borehole. Up until the early mid 1970's or SO<br>the use of borehole geophysics were largely confined to the petroleum industry. The advancement of microelectronics has brought borehole geophysics to the water well industry by allowing the downhole probes to be smaller in diameter, lighter weight and more affordable. Borehole geophysical logs compliment other types of data collected during a site investigation such as <br>cuttings, cores and surface geophysical data. Borehole geophysical logs have several unique features in that they can be run quickly, in small diameter mudded and/or cased holes (almost all logs can now be run in two-inch casing). Many logs can ilsee" through casing, but more importantly they provide a continuous record of various borehole parameters of interest to a hydrogeologist, particularly: bulk porosity, resistivity, density, and clay content. An experienced log analyst can take this information much in the same manner as an experienced hydrogeologist observes a core and analyzes what he sees. From this information the hydrogeologic characteristics can be used to map hydrostatigraphic units across the study area and develop a better understanding of vertical lithologic gradations and lateral facies changes essential to the development of a good understanding of the site hydrogeology. Currently, most borehole geophysical logging is used in a semiquantitative manner to assess lateral and vertical variations. Calibrated and compensated geophysical logs are available and could be used more effectively to more precisely determine: formation bulk porosity, matrix density, formation resistivity, clay content, carbonate content, water quality and even permeability and some cases vertical migration of contaminants. In summary, logs are capable of providing a continuous record of numerous parameters in a small diameter hole and in a timely manner, hydrogeologists take this data, fit it into a working hydrological model of the site to better understand the groundwater flow system.
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Lithology
Economic geology
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The primary objective of this work is to perform a complete characterization of the Womack Hill (oil) Field in Southern Alabama using petrophysical and reservoir performance data — and to provide reservoir management strategies that lead to improved oil recovery at Womack Hill Field. The process for achieving this goal requires the following specific objectives: To develop correlations between the core and well log data in order to generate spatial distributions of reservoir properties such as: porosity, permeability, net pay, etc.To analyze the production history on a per well basis using the decline type curve technique which provides estimates of the following properties: —Oil-in-place (N),—Effective permeability (k),—Flow capacity (kh),—Reservoir drainage area (A), and—Near-well skin factor (5).To determine the Estimated Ultimate Recovery (or EUR) for each well using the historical production data. The EUR is used to establish the volume of recoverable oil-in-place.To draw conclusions and provide recommendations regarding infill drilling, well completions, and production practices based on the results of integrating the geological data and the production history analysis.
Petrophysics
Reservoir Simulation
Oil in place
Oil Production
Infill
Petroleum reservoir
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ABSTRACT Quality, availability and consistency of the measured and interpreted well log data are essential in the seismic reservoir characterization methods, and seismic petrophysics is the recommended workflow to achieve data consistency between logs and seismic domains. This paper uses seismic petrophysics workflow to improve well logs and pore geometry interpretations for an oil carbonate reservoir in the Fahliyan Formation in the southwest of Iran. The petrophysical interpreted well logs, rock physics and well‐to‐seismic tie analysis are integrated into the proposed workflow. Our implementation incorporates revising petrophysical well log interpretations and updating pore geometry characteristics to obtain a better well‐tie quality. We first propose an improved pore‐type characterization approach based on both P‐ and S‐wave velocities for quantifying pore geometry. Then, seismic logs are estimated accordingly, and the results are used in the well‐to‐seismic analysis. The quality of the well‐tie is improved, furthermore, by iterating on the petrophysical interpreted well logs as well as the calculated pore geometries. For the intervals with high‐quality data, our workflow improves the consistency between the results of measured and modelled seismic logs. For the intervals with problematic well logs, the application of our proposed workflow results in the successful replacement of the poor data and subsequently leads to an improved wavelet estimation and well‐tie results. In both cases, a higher quantification of pore geometries is achieved, which in turn is confirmed by the core images and formation micro‐imager analysis.
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Seismic to simulation
Characterization
Formation evaluation
Seismic attribute
Environmental geology
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This study explores the application of data-driven modeling and prediction in reservoir characterization and simulation using seismic and petrophysical data analyses. Different aspects of the application of data-driven modeling methods are studied, which include rock facies classification, seismic attribute analyses, petrophysical properties prediction, seismic facies segmentation, and reservoir dimension reduction.
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Seismic to simulation
Characterization
Seismic attribute
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Abstract In carbonates, the geological facies is a key driver for populating reservoir models with petrophysical properties. Conventionnal core analysis mainly contributes to establish relationships between facies, petrophysics and geophysics. However, populating gridblocks reservoir models with petrophysics requires parsimonious facies classifications and effective relationships at larger scales that field studies rarely investigate. Studying outcrop analogues helps filling the gap between lab measurements and effective upscaled properties of models, and considerably improves the modelling workflows. The ALBION R&D project developed an innovative framework for multi-physics and multi-scales characterization of Barremian-Aptian carbonates from south-eastern France. These outcropping rudist-rich limestones constitute an analogue of Middle-East reservoirs. Petrophysical and geophysical properties were measured on plugs from cores and outcrops but also at larger scales thanks to original experiments on cores, in and between boreholes. Indeed the analogue includes several experimental areas, where hydraulic tests in sealed wells sections and tomographies between very close boreholes allowed investigating petrophysical and geophysical rock properties at intermediate decimetric to decametric scales. Thanks to the resulting database, this paper aims quantifying the variability of multi-physics data (e.g. porosity, permeability, and P-wave velocity) at different scales in regards of an updated and unified facies classification. The latter is only based on sedimentary origin and fabrics. Other available properties affecting petrophysics are used to cluster facies associations in sub-classes. Consequently the facies classification does not allow discriminating the distributions of porosity, permeability, nor p-wave velocity. For the rudist facies, that is the most sampled, texture subclasses do not help this work. Reversely, the place of sampling, that is likely a proxy of diagenesis and age, cluster the petrophysical distributions. The results remind us that a proper facies definition should consider both sedimentary origin, fabrics, texture, diagenesis and tectonics. They also point out the relative importance of each characteristics in regards of the scale of interest and the difficulty to infer upscaled relationships between rock properties from CCAL because the representative elementary volume of carbonates is usually higher than the plug and even the core volumes.
Petrophysics
Outcrop
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The evaluation of petroleum reservoirs has shifted from single approach to an integrated approach. The integration, analysis and understanding of all available data from the well bore and creating property models is an exceptional way to characterize a reservoir. Formulating, implementing, and demonstrating the applicability of the joint inversion of seismic and well-bore related observations, and the use of information about the relationship between porosity and permeability as the key parameters for identifying the rock types and reservoir characterization is a vital approach in this study. Correlating well and seismic data, potential reservoirs can be delineated and important horizons (markers) can be pointed out to better characterize the reservoir. This thesis aims to evaluate the potential petroleum reservoirs of the Wells K-A1, K-A2, K-A3 and K-H1 of the Shungu Shungu field in the Orange Basin through the integration and comparison of results from core analysis, wireline logs and seismic and attempt to produce a good reservoir model and by additionally utilizing Petrophysics and seismic and trying to better understand why the area has dry wells. Different rock types that comprise reservoir and non reservoirs are identified in the study and five Facie types are distinguished. Tight, fine grained sandstones with low porosity values ranging from 3% - 6% where dominant in the targeted sandstone layers. Porosity values ranging from 11% - 18% where identified in the massive sandstone lithologies which where hosted by Well’s K-A2 and K-A3. Low permeability values reaching 0.1mD exist throughout the study area. Areas with high porosity also
host high water saturation values ranging from 70 – 84%. An improvement in the porosity values at deeper zones (3700m -3725m) and is apparent. Poroperm plots exhibit quartz cemented sandstones and density with neutron plot suggest that the sandstones in the area contain quarts and dolomite mineralization.Well K-A3, consist of a cluster by quartzitic sandstone, meaning there is a large amount of sandstone present. There are apparent high porosity values around the sandstone. What is apparent from this plot is that there are many clusters that are scattered outside the chart. This could suggest some gas expulsions within this Well. Sandstones within the 14B2t1 to 14At1 interval are less developed in the vicinity covered by well K-A2 than at the K-A1 well location. The main targeted sandstones belong to the lower cretaceous and lie just below 13At1. The four wells drilled in this area are dry wells. The areas/blocks surrounding this area have shown to possess encouraging gas shows and a comparative study could reveal better answers. At deeper zones of the well at an interval of 5350m -5750m, there are more developed sandstones with good porosity values. The volume of shale is low and so is the water saturation. The main target sandstones in the study area are the Lower Cretaceous sandstones which are at an interval 13At1. These sandstones are not well developed but from the property…
Petrophysics
Lithology
Wireline
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Logging data from gamma ray, neutron-porosity, density, resistivity etc, are helpful to perform the qualitative and quantitative evaluation of the drilled wells. Parameters like water resistivity, porosity, water saturation etc, can be estimated by using the logging data. The Archie equation based method was a suitable method for all zones, due to the fact that no zone of interesting showed volume of shale bigger that 50%. In order to determine the water saturation in the formation, formula expressing the relationship between the true resistivity (Rt) and the formation parameters affecting the resistivity was used. The picket plot was a suitable method to estimate the water resistivity. Could be concluded that when no pressure data is available, as in the case of JOIA well, the logging curves, neutron and density, by plotting them in the neutron –density crossplot (qualitative evaluation), can be used to estimate the type of fluid in the formation. Although the results were not as accurate as from the pressure or core data. The neutron-density crossplot is indicating existence of oil in JOIA well reservoir.To have good permeability estimation, it’s necessary to have enough core data so that the regression line can be drawn. This paper presented applications of the petrophysical theories for qualitative and quantitative evaluation of two explorations wells of offshore Angola that will be called EKS and JOIA well respectively, with help of a petrophysical software called Techlog.
Petrophysics
Formation evaluation
Saturation (graph theory)
Water saturation
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Wireline
Coring
Logging while drilling
Sonic logging
Lithology
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