scholarly journals Effective medium modeling of diagenesis impact on the petroacoustic properties of carbonate rocks

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. WA43-WA57 ◽  
Author(s):  
Mathilde Adelinet ◽  
Jean-François Barthélémy ◽  
Elisabeth Bemer ◽  
Youri Hamon
Keyword(s):  
Elastic Properties ◽  
Carbonate Rocks ◽  
Effective Medium ◽  
Petrographic Analysis ◽  
Permeability Evolution ◽  
Data Set ◽  
Microstructural Parameters ◽  
Acoustic Signature ◽  
Extensive Experimental Data ◽  
The Impact

Carbonate formations are highly heterogeneous, and the velocity-porosity relationships are controlled by various microstructural parameters, such as the types of pores and their distribution. Because diagenesis is responsible for important changes in the microstructure of carbonate rocks, we have extended the standard effective medium approach to model the impact of diagenesis on the carbonate elastic properties through a step-by-step effective medium modeling. Two different carbonate rocks deposited, respectively, in lacustrine and marine environments are considered in this study. The first key step is the characterization of the diagenesis, which affected the two studied carbonate sample sets. Effective medium models integrating all of the geologic information accessible from petrographic analysis are then built. The evolution of the microstructural parameters during diagenesis is thoroughly constrained based on an extensive experimental data set, including X-ray diffraction analysis, different porosimetry methods, and ultrasonic velocity measurements. A new theoretical approach including two sources of compliance is developed to model the specific behavior of carbonates. A compliant interface is introduced around the main carbonate grains to represent grain contacts and the different pore scales are taken into account through multiscale modeling. Finally, direct calculations with the model provide elastic wave velocities representative of the different diagenetic stages. An extrapolation to permeability evolution is also introduced. This approach allows the identification of the acoustic signature of specific diagenetic events, such as dolomitization, dissolution, or cementation, and the assessment of their impact on the elastic properties of carbonates.

The complexity of carbonate porosity distribution in the Upper Marrat Formation, Central Saudi Arabia

2020 ◽  
Author(s):  
Saleh Ahmed ◽  
Luis González ◽  
Johannes Jozef Gerardus Reijmer ◽  
Ammar ElHusseiny
Keyword(s):  
Saudi Arabia ◽  
Carbonate Rocks ◽  
Early Jurassic ◽  
Arabian Plate ◽  
Permeability Evolution ◽  
Depositional Processes ◽  
Bedding Planes ◽  
Tectonic Processes ◽  
Porosity And Permeability ◽  
The Impact

<p>In terms of reservoir properties distribution carbonate rocks are very heterogeneous. Moreover, the types of porosity in carbonate rocks is very diverse. In our study of the Upper Marrat Formation near Khasm-adh-Dhibi (central Saudi Arabia) we have documented the pore system complexity and are deconvolving the impact of various post-depositional processes on porosity and permeability evolution of the formation. The Upper Marrat Formation is exposed in the central part of the Arabian plate in a north-south elongated mountain belt. It forms the lower part of the thick Jurassic petroleum-rich succession. The sediments forming the Upper Marrat Formation were deposited during the Early Jurassic time, the Toarcian. The Upper Marrat Formation shows fossiliferous biomicrite to sparse biomicrite carbonates with an evaporite deposit at the top. It is bounded by clayey units at both the top and the base. In general, because of the muddy matrix of the Upper Marrat, sediments are very tight and show low permeability. During the last 175 My, the Upper Marrat has been subjected to a series of diagenetic and tectonic processes. The initial micro- and intergranular porosity was reduced due to early compaction and cementation, however, during later diagenesis and tectonism, porosity and permeability were enhanced. The dominant diagenetic porosity in the Upper Marrat sediments is vuggy porosity, followed by fabric selective intragranular porosity. Many of the horizons in the Upper Marrat are heavily burrowed and mostly filled with sand-sized grains showing a higher porosity than the matrix. Dolomite is limited to evaporite strata and contain extensive inter-crystalline porosity produced during dolomite formation. Tectonism has enhanced porosity through the development of micro- and macro-fractures.  The different sized and orientated micro-fractures are important while they enhance permeability by connecting different pore types. Then extensive macro-fracture network has a major impact on the reservoir qualities, both porosity and permeability. The heavily fractured formation shows numerous fractures sets with NNE to SSW and ENE to WNW orientations. Fractures are mostly vertical to near-vertical; they are nearly all open, and often crosscut beds, or end at bedding planes. These fractures are the most abundant porosity type and their connectivity results in a very high permeability. In conclusion, initial porosity and permeability, and subsequent diagenetic and tectonic processes reduced and enhanced the porosity and permeability development of the sediments of the Early Jurassic Upper Marrat Formation.</p>

Prediction of sonic velocities in shale from porosity and clay fraction obtained from logs — A North Sea well case study

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. D1-D10 ◽  
Author(s):  
Marina Pervukhina ◽  
Pavel Golodoniuc ◽  
Boris Gurevich ◽  
Michael B. Clennell ◽  
Dave N. Dewhurst ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Vertical Section ◽  
Order Approximation ◽  
Clay Fraction ◽  
Effective Medium ◽  
Data Quality Control ◽  
Data Set ◽  
Silt Fraction ◽  
Effective Medium Model ◽  
Elastic Coefficients

Prediction of sonic velocities in shales from well logs is important for seismic to log ties if the sonic log is absent for a shaly section, for pore pressure anomaly detection, and for data quality control. An anisotropic differential effective medium (DEM) was used to simulate elastic properties of shales from elastic properties and volume fractions of silt and wet clay (a hypothetical composite material that includes all clay minerals and water). Anisotropic elastic coefficients of the wet clay were assumed as a first-order approximation to be linearly dependent on wet clay porosity (WCP). Here, by WCP we mean a ratio of a pore volume occupied by water to a total volume of the wet clay. Effects of silt inclusions on elastic coefficients of shales were taken into account by using the anisotropic differential effective medium model. Silt inclusions were modeled as spherical quartz particles. Simulated elastic coefficients of shales were used to calculate compressional and shear velocities, and these were in a good agreement with the sonic velocities observed on a test data set from an offshore Mid-Norway well penetrating a 500-m vertical section of shale. To further study the elastic properties of wet clays, elastic coefficients calculated from compressional and sonic velocities measured in shales were inverted for vertical profiles of wet clay elastic coefficients. Analysis of these coefficients found that in the well considered, the increase in elastic coefficients of shales was controlled by the increase of silt fraction with depth. Elastic coefficients of wet clay found no increase with depth. The inverted elastic moduli of wet clay found much stronger correlation with WCP than do the moduli of shale. This confirmed the hypothesis that silt fraction is one of the key parameters for the modeling of elastic properties of shale.

scholarly journals Elastic properties of continental carbonates: From controlling factors to an applicable model for acoustic-velocity predictions

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. MR45-MR59 ◽  
Author(s):  
Jean-Baptiste Regnet ◽  
Jérôme Fortin ◽  
Aurélien Nicolas ◽  
Matthieu Pellerin ◽  
Yves Guéguen
Keyword(s):  
Aspect Ratio ◽  
Elastic Properties ◽  
Carbonate Rocks ◽  
Effective Medium ◽  
Acoustic Velocity ◽  
Controlling Factors ◽  
S Wave ◽  
Wave Velocities ◽  
Diagenetic Alteration ◽  
Continental Carbonates

We have provided new insights into the controlling factors of elastic properties in continental carbonate rocks and introduced an applicable model for acoustic-velocity predictions in such a medium. Petrophysical properties (porosity, permeability, P- and S-wave velocities) from laboratory measurements have been coupled with thin-section observations and characterizations, and X-ray diffraction (XRD) analyses. A major achievement is the establishment of the link between the mineralogical composition and the P- and S-wave velocity dispersion at a given porosity. This reflects the subtle interplay between physicochemical and biological precipitation of continental carbonates, which can also be associated with a strong influence of detrital mineralogical inputs. The result is a mineralogical commixture, coupled to a wide array of pore types inherited from the strong ability of carbonate rocks to undergo diagenetic alteration. The proposed model takes into account the elastic moduli of the minerals, porosity, and pore shape, and it is based on the effective medium theory. We have considered the case in which the medium contained randomly oriented pores with different aspect ratios. Overall, the fit between the predicted trends and the experimental data is fairly good, especially for calcite and quartz matrix mineralogy. The results are even better when considering mineralogy inferred from XRD data, although in some case, and despite the aspect ratio variation in both simulations, the model fails to accurately predict the P-wave velocities. This probably means that another factor is at stake beside mineralogy. This can be explained by the limitation of the effective medium approach, which oversimplifies the reality and fails to account for the variability of some aspect ratio from one inclusion to another.

Elastic properties of microporous cemented grainstones

Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. E211-E226 ◽  
Author(s):  
François Fournier ◽  
Philippe Leonide ◽  
Kévin Biscarrat ◽  
Arnaud Gallois ◽  
Jean Borgomano ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Pore Space ◽  
Micropore Volume ◽  
Pore Geometry ◽  
Petrographic Analysis ◽  
S Wave ◽  
Lower Porosity ◽  
Diagenetic History ◽  
Space Architecture ◽  
The Impact

We investigated the effect of porosity, pore geometry, and diagenetic history on the elastic properties of dry, tightly cemented grainstones whose pore space consists dominantly of intragranular microporosity within micritic grains. The integration of laboratory petrophysical measurements (porosity, P- and S-wave velocity), petrographic analysis and scanning electron microscope (SEM) imaging of micropore space of 80 Lower Cretaceous microporous carbonate samples from Provence (south-east France) allows (1) the changes in porosity and pore geometry during the diagenetic history to be related to changes in elastic properties, and (2) the impact of micritic grain diagenesis on the elastic properties of microporous grainstones to be quantified by means of fitting parameters derived from equivalent elastic medium modeling. The Urgonian microporous cemented grainstones are elastically equivalent to a homogeneous calcitic host with spherical calcitic inclusions comprising spheroidal pores. The best fit is obtained when porous spheres are modelled using the differential effective medium (DEM) approach and the whole composite using the self-consistent (SC) method (DEM-SC model). At lower porosity values ([Formula: see text]), when the micropore volume is controlled by intercrystalline cementation processes without compaction, the equivalent pore aspect ratio (EPAR) derived from DEM-SC modelling is nearly constant and averages 0.15. At higher porosities, changes in micropore space architecture related to leaching processes result in slightly increasing EPAR. The recognition of EPAR-preserving versus EPAR-non preserving elastic property evolution is proposed as a tool for diagenetic pattern detection in microporous carbonate reservoirs.

Age at Exposure to Parental Suicide and the Subsequent Risk of Suicide in Young People

Crisis ◽  
2018 ◽  
Vol 39 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Kuan-Ying Lee ◽  
Chung-Yi Li ◽  
Kun-Chia Chang ◽  
Tsung-Hsueh Lu ◽  
Ying-Yeh Chen
Keyword(s):  
Young People ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Birth Registry ◽  
Data Set ◽  
Parental Suicide ◽  
The Impact ◽  
Age At Exposure

Abstract. Background: We investigated the age at exposure to parental suicide and the risk of subsequent suicide completion in young people. The impact of parental and offspring sex was also examined. Method: Using a cohort study design, we linked Taiwan's Birth Registry (1978–1997) with Taiwan's Death Registry (1985–2009) and identified 40,249 children who had experienced maternal suicide (n = 14,431), paternal suicide (n = 26,887), or the suicide of both parents (n = 281). Each exposed child was matched to 10 children of the same sex and birth year whose parents were still alive. This yielded a total of 398,081 children for our non-exposed cohort. A Cox proportional hazards model was used to compare the suicide risk of the exposed and non-exposed groups. Results: Compared with the non-exposed group, offspring who were exposed to parental suicide were 3.91 times (95% confidence interval [CI] = 3.10–4.92 more likely to die by suicide after adjusting for baseline characteristics. The risk of suicide seemed to be lower in older male offspring (HR = 3.94, 95% CI = 2.57–6.06), but higher in older female offspring (HR = 5.30, 95% CI = 3.05–9.22). Stratified analyses based on parental sex revealed similar patterns as the combined analysis. Limitations: As only register-­based data were used, we were not able to explore the impact of variables not contained in the data set, such as the role of mental illness. Conclusion: Our findings suggest a prominent elevation in the risk of suicide among offspring who lost their parents to suicide. The risk elevation differed according to the sex of the afflicted offspring as well as to their age at exposure.

State Medical Boards' Perceptions of a Minimum Data Set and Current Practices for Collecting Physician Information

2013 ◽  
Vol 99 (4) ◽  
pp. 40-45 ◽  
Author(s):  
Aaron Young ◽  
Philip Davignon ◽  
Margaret B. Hansen ◽  
Mark A. Eggen
Keyword(s):  
Media Coverage ◽  
The United States ◽  
Minimum Data Set ◽  
Direct Patient Care ◽  
Physician Workforce ◽  
Data Set ◽  
Minimum Data ◽  
State Medical Boards ◽  
The Impact ◽  
Current Practices

ABSTRACT Recent media coverage has focused on the supply of physicians in the United States, especially with the impact of a growing physician shortage and the Affordable Care Act. State medical boards and other entities maintain data on physician licensure and discipline, as well as some biographical data describing their physician populations. However, there are gaps of workforce information in these sources. The Federation of State Medical Boards' (FSMB) Census of Licensed Physicians and the AMA Masterfile, for example, offer valuable information, but they provide a limited picture of the physician workforce. Furthermore, they are unable to shed light on some of the nuances in physician availability, such as how much time physicians spend providing direct patient care. In response to these gaps, policymakers and regulators have in recent years discussed the creation of a physician minimum data set (MDS), which would be gathered periodically and would provide key physician workforce information. While proponents of an MDS believe it would provide benefits to a variety of stakeholders, an effort has not been attempted to determine whether state medical boards think it is important to collect physician workforce data and if they currently collect workforce information from licensed physicians. To learn more, the FSMB sent surveys to the executive directors at state medical boards to determine their perceptions of collecting workforce data and current practices regarding their collection of such data. The purpose of this article is to convey results from this effort. Survey findings indicate that the vast majority of boards view physician workforce information as valuable in the determination of health care needs within their state, and that various boards are already collecting some data elements. Analysis of the data confirms the potential benefits of a physician minimum data set (MDS) and why state medical boards are in a unique position to collect MDS information from physicians.

The Impact of Green Labels on U.S. Hotel Net Operating Income: Operating Statements Analyses

2019 ◽  
Vol 11 (1) ◽  
pp. 156-173
Author(s):  
Spenser Robinson ◽  
A.J. Singh
Keyword(s):  
Environmental Design ◽  
Green Buildings ◽  
Small Sample ◽  
Sample Survey ◽  
Data Set ◽  
Operating Income ◽  
Energy Star ◽  
The Impact ◽  
Industry Professionals

This paper shows Leadership in Energy and Environmental Design (LEED) certified hospitality properties exhibit increased expenses and earn lower net operating income (NOI) than non-certified buildings. ENERGY STAR certified properties demonstrate lower overall expenses than non-certified buildings with statistically neutral NOI effects. Using a custom sample of all green buildings and their competitive data set as of 2013 provided by Smith Travel Research (STR), the paper documents potential reasons for this result including increased operational expenses, potential confusion with certified and registered LEED projects in the data, and qualitative input. The qualitative input comes from a small sample survey of five industry professionals. The paper provides one of the only analyses on operating efficiencies with LEED and ENERGY STAR hospitality properties.

Does Tax Increment Financing Pass the “But-for” Test in Missouri?

2019 ◽  
Vol 33 (3) ◽  
pp. 187-202
Author(s):  
Ahmed Rachid El-Khattabi ◽  
T. William Lester
Keyword(s):  
Economic Development ◽  
Kansas City ◽  
Time Series Data ◽  
Local Level ◽  
Conclusive Evidence ◽  
Series Data ◽  
Tax Increment Financing ◽  
Data Set ◽  
Development Indicators ◽  
The Impact

The use of tax increment financing (TIF) remains a popular, yet highly controversial, tool among policy makers in their efforts to promote economic development. This study conducts a comprehensive assessment of the effectiveness of Missouri’s TIF program, specifically in Kansas City and St. Louis, in creating economic opportunities. We build a time-series data set starting 1990 through 2012 of detailed employment levels, establishment counts, and sales at the census block-group level to run a set of difference-in-differences with matching estimates for the impact of TIF at the local level. Although we analyze the impact of TIF on a wide set of indicators and across various industry sectors, we find no conclusive evidence that the TIF program in either city has a causal impact on key economic development indicators.

Evaluation of the Aging Behavior of High Density Polyethylene in Thermal Oxidative Environment by Principal Component Analysis

2017 ◽  
Vol 727 ◽  
pp. 447-449 ◽  
Author(s):  
Jun Dai ◽  
Hua Yan ◽  
Jian Jian Yang ◽  
Jun Jun Guo
Keyword(s):  
Principal Component Analysis ◽  
Impact Strength ◽  
High Density Polyethylene ◽  
Tensile Modulus ◽  
Principal Component ◽  
Component Analysis ◽  
High Density ◽  
Aging Behavior ◽  
Data Set ◽  
The Impact

To evaluate the aging behavior of high density polyethylene (HDPE) under an artificial accelerated environment, principal component analysis (PCA) was used to establish a non-dimensional expression Z from a data set of multiple degradation parameters of HDPE. In this study, HDPE samples were exposed to the accelerated thermal oxidative environment for different time intervals up to 64 days. The results showed that the combined evaluating parameter Z was characterized by three-stage changes. The combined evaluating parameter Z increased quickly in the first 16 days of exposure and then leveled off. After 40 days, it began to increase again. Among the 10 degradation parameters, branching degree, carbonyl index and hydroxyl index are strongly associated. The tensile modulus is highly correlated with the impact strength. The tensile strength, tensile modulus and impact strength are negatively correlated with the crystallinity.

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