scholarly journals ROCK PHYSICS TEMPLATE TO ESTIMATE THE EFFECTS OF TOTAL ORGANIC CARBON (TOC) AND MINERALOGY ON THE SEISMIC ELASTIC PROPERTIES OF IMMATURE SHALE RESERVOIR

2019 ◽  
Vol 42 (2) ◽  
pp. 43-49
Author(s):  
Harnanti Y Hutami ◽  
Tiara Larasati Priniarti ◽  
Ign Sonny Winardhi ◽  
Handoyo .
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Elastic Properties ◽  
Rock Physics ◽  
P Wave ◽  
General Distribution ◽  
Effective Elastic Properties ◽  
Shale Reservoirs ◽  
The Impact

The low porosity and permeability shale are nowadays known as self-resourcing reservoirs. In the unique organic shales, TOC has a signifi cant contribution to the elastic properties of rocks. TOC behaves like porosity to a density log and effects in decreasing density. To reduce the uncertainty due to TOC and mineral variability effect, a quantitative interpretation of shale reservoirs should be done properly to obtain the best image of shale systems. In this study, we built rock-physics templates (RPT) to esti mate seismic response by defi ning the relationship between total organic carbon (TOC) and effective elastic properties of shale reservoirs of a data set from South Sumatera Basin, Indonesia. RPT is carried out by incorporating the amount of organic matter into shale pore space as a solid-fi lling inclusion. Moreover, shale porosity is assumed to be fully water-saturated determined by the in-situ conditions. We have estimated the general distribution of pore geometry by investigating aspect ratio from the dataset. A solid background of shale from several different minerals is estimated by using effective medium theory. Properties of porous rocks for solid pore infi ll are estimated from a generalization of Brown-Korringa Equation. Effective elastic properties of bulk rock frame fi lled with a fl uid are obtained from Gassmann equations. Results show that increasing the TOC volumes generally reduces both P-wave and S-wave velocities, acoustic impedance, and density. On the contrary, the vp/vs ratio increased as the impact of immature organic matter which will be more affecting shale rigidity than its compressibility.

scholarly journals Sources and export of particle-borne organic matter during a monsoon flood in a catchment of northern Laos

2014 ◽  
Vol 11 (6) ◽  
pp. 9341-9378
Author(s):  
E. Gourdin ◽  
S. Huon ◽  
O. Evrard ◽  
O. Ribolzi ◽  
T. Bariac ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Particulate Organic Matter ◽  
Rainy Season ◽  
Overland Flow ◽  
Specific Yield ◽  
Δ13c And Δ15n ◽  
Teak Plantations ◽  
The Impact

Abstract. Tropical rivers of Southeast Asia are characterized by high specific carbon yields and supplies to the ocean. The origin and dynamics of particulate organic matter were studied in the Houay Xon River catchment located in northern Laos during the first erosive flood of the rainy season in May 2012. The partly cultivated catchment is equipped with three successive gauging stations draining areas ranging between 0.2 and 11.6 km2 on the main stem of the permanent stream, and two additional stations draining 0.6 ha hillslopes. In addition, the sequential monitoring of rainwater, overland flow and suspended organic matter compositions was realized at 1 m2 plot scale during a single storm. The composition of particulate organic matter (total organic carbon, total nitrogen, δ13C and δ15N) was determined for suspended sediment, soil surface and subsurface samples collected in the catchment (n = 57, 65 and 11 respectively). Hydrograph separation of event water was conducted using water electric conductivity and δ18O data measured for rainfall, overland flow and river water base flow (n = 9, 30 and 57, respectively). The composition of particulate organic matter indicates that upstream suspended sediments were mainly derived from cultivated soils labelled by their C3 vegetation cover (upland rice, fallow vegetation and teak plantations) but that collapsed riverbanks, characterized by C4 vegetation occurrence (Napier grass), significantly contributed to sediment yields during water level rise and at the downstream station. The highest runoff coefficient (11.7%), sediment specific yield (433 kg ha−1), total organic carbon specific yield (8.3 kg C ha−1) and overland flow contribution (78–100%) were found for the reforested areas covered by teak plantations. Total organic carbon specific yields were up to 2.6-fold higher (at downstream station) than the annual ones calculated 10 years earlier, before the expansion of teak plantations in the catchment. They may be attributed both to the sampling period at the onset of the rainy season (following field clearing by slash and burn) and to the impact of land use change during the past decade.

Quantifying the links between geochemical and geophysical properties of organic-rich carbonate mudrocks

2019 ◽  
Vol 38 (12) ◽  
pp. 914-922 ◽  
Author(s):  
Mita Sengupta ◽  
David Jacobi ◽  
Yazeed Altowairqi ◽  
Salma Al-Sinan
Keyword(s):  
Organic Matter ◽  
Seismic Response ◽  
Elastic Properties ◽  
Rock Physics ◽  
Source Rocks ◽  
Geochemical Data ◽  
Clear Understanding ◽  
Velocity Measurements ◽  
Geochemical Properties ◽  
The Impact

Source rocks possess complex heterogeneous matrices with soft organic matter, consisting mainly of kerogen, interspersed within a stiff inorganic mineral framework that varies in composition. There is not a clear understanding nor adequate knowledge of how geochemical properties influence the rock physics, especially when predicting a seismic response. While many attempts have been made to use seismic to empirically quantify these properties for the purpose of exploration, those attempts have often failed due to the complexity of the elastic properties of kerogen and the laminated geometry of the rock. This is due primarily to uncertainty over how these properties change with maturity as a result of burial and subsequent uplift. Therefore, knowledge of (1) the elastic properties of kerogen, (2) the amount and geometric distribution of organic matter within the rock matrix, and (3) the impact of kerogen maturity on its elastic properties is needed to predict a seismic response. An elastic property modeling method has been developed to address this challenge based on the integration of high-resolution microscopy, geochemical analysis, and velocity measurements. Using this approach, endmembers are obtained that allow for building rock-physics models that can predict elastic uncertainty from mineral heterogeneity and estimate the elastic properties of organic matter. Digital images, geochemical data, and velocity measurements coupled with maturity modeling suggest that bulk and shear softening of kerogen can help distinguish between maturity-induced seismic responses.

scholarly journals The Impact of Organic Matter on Polycyclic Aromatic Hydrocarbon (PAH) Availability and Persistence in Soils

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2470 ◽  
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Bożena Smreczak
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Agricultural Soils ◽  
Soil Surface ◽  
Turnover Time ◽  
Organic Carbon Content ◽  
Human Beings ◽  
Polycyclic Aromatic ◽  
The Impact

Polycyclic aromatic hydrocarbons (PAHs) exhibit persistence in soils, and most of them are potentially mutagenic/carcinogenic and teratogenic for human beings but also influence the growth and development of soil organisms. The PAHs emitted into the atmosphere are ultimately deposited (by dry or wet deposition processes) onto the soil surface where they tend to accumulate. Soil organic matter (SOM) plays an important role in the fate and transformation processes of PAHs, affecting their mobility, availability, and persistence. Therefore, the aim of this research was to investigate the influence of SOM fractional diversification (fulvic acids—FA, humic acids—HA, and humins—HN) on PAH availability and persistence in soils. Twenty soil samples (n = 20) were collected from upper horizons (0–30 cm) of agricultural soils exposed to anthropogenic emissions from industrial and domestic sources. The assessment of PAH concentrations included the determination of medium-molecular-weight compounds from the US EPA list: fluoranthene—FLA, pyrene—PYR, benz(a)anthracene—BaA, and chrysene—CHR. The assessment was conducted using the GC-MS/MS technique. Three operationally defined fractions were investigated: total extractable PAHs (TE-PAHs) fraction, available/bioavailable PAHs (PB-PAHs) fraction, and nonavailable/residual PAHs (RE-PAHs) fraction, which was calculated as the difference between total and available PAHs. TE-PAHs were analyzed by dichloromethane extraction, while PB-PAHs were analyzed with a hydrophobic β-cyclodextrin solution. SOM was characterized by total organic carbon content (Turin method) and organic carbon of humic substances including FA, HA, HN (IHSS method). Concentrations of PAHs differed between soils from 193.5 to 3169.5 µg kg−1, 4.3 to 226.4 µg kg−1, and 148.6 to 3164.7 µg kg−1 for ∑4 TE-PAHs, ∑4 PB-PAHs, and ∑4 RE-PAHs, respectively. The ∑4 PB-PAHs fraction did not exceed 30% of ∑4 TE-PAHs. FLA was the most strongly bound in soil (highest content of RE-FLA), whereas PYR was the most available (highest content of PB-PYR). The soils were characterized by diversified total organic carbon (TOC) concentration (8.0–130.0 g kg−1) and individual SOM fractions (FA = 0.4–7.5 g kg−1, HA = 0.6–13.0 g kg−1, HN = 0.9–122.9 g kg−1). FA and HA as the labile fraction of SOM with short turnover time strongly positively influenced the potential ∑4 PAH availability (r = 0.56 and r = 0.52 for FA and HA, respectively). HN, which constitutes a stable fraction of organic matter with high hydrophobicity and poor degradability, was strongly correlated with ∑4 RE-PAHs (r = 0.75), affecting their persistence in soil.

Seismic data conditioning and orthotropic rock-physics-based inversion of wide-azimuth P-wave seismic data for fracture and total organic carbon characterization in a north Kuwait unconventional reservoir

Geophysics ◽  
2018 ◽  
Vol 83 (4) ◽  
pp. B229-B240 ◽  
Author(s):  
Rajive Kumar ◽  
Prashant Bansal ◽  
Bader S. Al-Mal ◽  
Sagnik Dasgupta ◽  
Colin Sayers ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Seismic Data ◽  
Rock Physics ◽  
Seismic Inversion ◽  
P Wave ◽  
Natural Fracture ◽  
Reservoir Properties ◽  
Fluid Saturation ◽  
Fracture Intensity

Optimization of production from unconventional reservoirs requires estimates of reservoir properties such as porosity, total organic carbon (TOC) content, clay content, fluid saturation, and fracture intensity. The porosity and TOC content help to determine reservoir quality, and the natural fracture intensity provides information important for the completion strategy. Because shale reservoirs display intrinsic anisotropy due to layering and the partial alignment of clay minerals and kerogen with the bedding plane, the minimum acceptable representation of the anisotropy of naturally fractured shale-gas reservoirs is orthotropy, in which a set of vertical compliant fractures is embedded in a vertical transverse isotropic (VTI) background medium. Full-azimuth seismic data are required to characterize such reservoirs and to invert for the anisotropic elastic properties. Orthotropic inversion uses azimuthally sectored seismic data stacked according to the incident angle. Even for high-fold acquisition, this azimuth/angle grouping can result in low-fold angle stacks. Orthotropic amplitude-variation-with-offset-and-azimuth (AVOAz) inversion requires seismic preconditioning techniques that ensure proper primary amplitude preservation, noise attenuation, and data alignment, and a workflow implemented for the construction of an orthotropic rock-physics model. This model integrates well and core data to estimate reservoir properties using the results of the AVOAz inversion. The seismic inversion results include the P- and S-impedance and parameters quantifying the azimuthal anisotropy. The rock model assumes a VTI kerogen-rich layer, containing aligned vertical fractures, and it uses prestack orthotropic AVOAz inversion results to predict porosity, TOC, and fracture intensity.

Influence of manure, compost additions and temperature on the water repellency of tropical soils

Soil Research ◽  
2018 ◽  
Vol 56 (7) ◽  
pp. 685 ◽  
Author(s):  
Kegan K. Farrick ◽  
Zakiya Akweli ◽  
Mark N. Wuddivira
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Soil Water ◽  
Water Repellency ◽  
Tropical Soils ◽  
Clay Loam ◽  
Soil Water Repellency ◽  
Manure Compost ◽  
The Impact

Soil water repellency is a major concern in many systems as it substantially reduces infiltration and enhances surface runoff. While it is recognised that repellency is affected by the soil organic matter in natural ecosystems, the impact of manure and compost additions on the development and persistence of repellency in agroecosystems, particularly in the tropics, is poorly understood. We therefore examined the impact of different manure, compost additions and temperature on soil water repellency of tropical soils. We monitored the change in repellency in a Cambisol (Talparo – clay loam), Acrisol (Piarco – silt loam) and Arenosol (Arena – loamy sand), amended with three different manure and compost combinations at three different concentrations and four temperatures. Water repellency was the strongest among soils with higher clay content, which was likely due to the higher levels of organic matter observed in the clay loam. The cattle manure produced the most severe repellency despite having the lowest total organic carbon, whereas the sugarcane bagasse produced the lowest repellency. The increases in temperature had the strongest influence on repellency in sandy soils. Our results strongly support the findings of other studies that the quality of the organic material is more important than the total organic carbon in controlling the severity of repellency. This exploratory work also highlighted the importance of plant compost in reducing the level of repellency caused by cattle manure while still having a positive influence on the nutrient status of soils.

scholarly journals 3D finite-element modeling of effective elastic properties for fracture density and multiscale natural fractures

2021 ◽  
Vol 18 (4) ◽  
pp. 567-582
Author(s):  
Shikai Jian ◽  
Li-Yun Fu ◽  
Chenghao Cao ◽  
Tongcheng Han ◽  
Qizhen Du
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Elastic Properties ◽  
Least Square ◽  
P Wave ◽  
Fracture Density ◽  
Equivalent Stiffness ◽  
Natural Fractures ◽  
Effective Elastic Properties ◽  
Element Modeling

Abstract Natural fractures are usually multiscale in size, orientations and distribution, resulting in complex anisotropic characteristics. Analytical methods for quantifying the associated effective elastic properties are based on some assumptions, such as dilute fracture concentration and regular-shaped fractures, which do not occur in actual reservoirs. Here, we conduct anisotropic finite-element modeling of effective elastic properties of complex fractured rocks using the least-square fitting method. The algorithm is developed for a 3D case and validated by classical effective medium theories for models with different fracture densities. The results of the 3D numerical method agree well with the theoretical predictions at low fracture density. The model also considers the interactions among fractures to calculate equivalent stiffness tensors at high fracture density. Three 2D fracture models are simulated to demonstrate the basic behavior of stress interactions and their effect on the overall elasticity under different fracture densities. We applied the developed model to 3D natural fractures built from a real outcrop, and we found that the fracturing pattern significantly affects the effective anisotropy properties. The resultant P-wave phase velocities as functions of the incidence angle and frequency are anisotropic. This study provides a great potential to calculate equivalent stiffness tensors and anisotropic properties of 3D multiscale natural fractures.

scholarly journals Characterization of organic matter from a stratigraphic sequence intercepted by the Nemo-1X well, Mozambique: Potential for hydrocarbon generation

2018 ◽  
Vol 36 (5) ◽  
pp. 1157-1171
Author(s):  
Agostinho Mussa ◽  
Deolinda Flores ◽  
Joana Ribeiro ◽  
Ana MP Mizusaki ◽  
Mónica Chamussa ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Hydrocarbon Exploration ◽  
Published Data ◽  
Organic Carbon Content ◽  
Hydrocarbon Generation ◽  
Offshore Area ◽  
Type Iii ◽  
Kerogen Type

The Mozambique Basin, which occurs onshore and offshore in the central and southern parts of Mozambique, contains a thick sequence of volcanic and sedimentary rocks that range in age from the Jurassic to Cenozoic. This basin, along with the Rovuma basin to the north, has been the main target for hydrocarbon exploration; however, published data on hydrocarbon occurrences do not exist. In this context, the present study aims to contribute to the understanding of the nature of the organic matter of a sedimentary sequence intercepted by the Nemo-1X exploration well located in the offshore area of the Mozambique Basin. The well reached a depth of 4127 m, and 33 samples were collected from a depth of 2219–3676 m ranging in age from early to Late Cretaceous. In this study, petrographic and geochemical analytical methods were applied to assess the level of vitrinite reflectance and the organic matter type as well as the total organic carbon, total sulfur, and CaCO3 contents. The results show that the total organic carbon content ranges from 0.41 to 1.34 wt%, with the highest values determined in the samples from the Lower Domo Shale and Sena Formations, which may be related to the presence of the solid bitumens that occur in the carbonate fraction of those samples. The vitrinite random reflectances range from 0.65 to 0.86%Rrandom, suggesting that the organic matter in all of the samples is in the peak phase of the “oil generation window” (0.65–0.9%Rrandom). The organic matter is mainly composed of vitrinite and inertinite macerals, with a minor contribution of sporinite from the liptinite group, which is typical of kerogen type III. Although all of the samples have vitrinite reflectances corresponding to the oil window, the formation of liquid hydrocarbons is rather limited because the organic matter is dominated by gas-prone kerogen type III.

Basin-wide rock-physics analysis in Campeche Basin, Gulf of Mexico — Phase II: Reservoir rock and fluid properties

2021 ◽  
Vol 40 (10) ◽  
pp. 716-722
Author(s):  
Yangjun (Kevin) Liu ◽  
Michelle Ellis ◽  
Mohamed El-Toukhy ◽  
Jonathan Hernandez
Keyword(s):  
Oil And Gas ◽  
Rock Physics ◽  
Clay Content ◽  
American Petroleum Institute ◽  
P Wave ◽  
Reservoir Rock ◽  
Gas Oil ◽  
Amplitude Variation With Offset ◽  
Fluid Properties ◽  
The Impact

We present a basin-wide rock-physics analysis of reservoir rocks and fluid properties in Campeche Basin. Reservoir data from discovery wells are analyzed in terms of their relationship between P-wave velocity, density, porosity, clay content, Poisson's ratio (PR), and P-impedance (IP). The fluid properties are computed by using in-situ pressure, temperature, American Petroleum Institute gravity, gas-oil ratio, and volume of gas, oil, and water. Oil- and gas-saturated reservoir sands show strong PR anomalies compared to modeled water sand at equivalent depth. This suggests that PR anomalies can be used as a direct hydrocarbon indicator in the Tertiary sands in Campeche Basin. However, false PR anomalies due to residual gas or oil exist and compose about 30% of the total anomalies. The impact of fluid properties on IP and PR is calibrated using more than 30 discovery wells. These calibrated relationships between fluid properties and PR can be used to guide or constrain amplitude variation with offset inversion for better pore fluid discrimination.

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