Importance of coloured inversion technique for thin hydrocarbon sand reservoir detection – A case in mid Cambay basin

Cambay basin is an intra-cratonic rift graben formed as a result of rifting which was occurred in late Cretaceous with Deccan lava eruption through linear trending NNW to SSE directional basin. The Deccan basalt forms the basement over which more than 7–11 km thick piles of Tertiary sediments have been deposited during syn-rift and post-rift phases of basin development. Cambay basin has been considered as one of the significant hydrocarbon prolific basin in India. The biggest challenge in current days for this basin is further exploration or exploration under development stage in small marginal field or unexplored left out areas in the basin part as most of the areas are already explored/discovered by various small to big E&;P (exploration &; production) industrial players. In this present study one such small marginal field has been chosen for “Exploration under Development” portfolio in mid Cambay basin. The amount of oil-in-place volume, investment and techno-economics analysis of small marginal field has made this study area. In view of further hydrocarbon exploration in this area this kind of study will provide a robust support in limited dataset. The reservoir sand quality of the study area is discrete, thin and less permeable. This kind of sand body detection through classical seismic interpretation approach is difficult and there will be always a big amount of uncertainties for findings the pay reservoir sand. In view of the limitation of available data and challenging geological setup of the reservoir, a quantitative approach has been taken to detect the thin reservoir sand in this study area. Primarily coloured inversion technique has been applied on post-stack seismic data based upon well to seismic correlation and reservoir sand detection in seismic interpretation and well log property analysis. This technique has produced higher detectability impedance/property volume with respect to normal post-stack seismic data signature. Based on high contrast impedance/elastic property further seismic based attribute analysis on reservoir section has been performed. The attribute analysis has been made along surface and 3D seismic data level, provided clear image about the thin hydrocarbon sand reservoir. Based upon quantitative interpretation approach coloured inverted volume the prospect was chosen for further drilling in the study area and drilling of that sand was turned to be a hydrocarbon discovery prospect. The unconventional approaches e.g. coloured inversion with limited dataset for this kind of small marginal field has potential to find the hydrocarbon.     

Hydrochemical appraisal of groundwater and its suitability in the intensive agricultural area of Muzaffarnagar district,Uttar Pradesh,India

Muzaffarnagar is an economically rich district situated in the most fertile plains of two great rivers Ganga and Yamuna in the Indo-gangetic plains, with agricultural land irrigated by both surface water as well as groundwater. An investigation has been carried out to understand the hydrochemistry of the groundwater and its suitability for irrigation uses. Groundwater in the study area is neutral to moderately alkaline in nature. Chemistry of groundwater suggests that alkaline earths (Ca + Mg) significantly exceed the alkalis (Na + K) and weak acids exceed the strong acids (Cl + SO₄), suggesting the dominance of carbonate weathering followed by silicate weathering. Majority of the groundwater samples (62%) posses Ca–Mg–HCO₃ type of hydrochemical species, followed by Ca–Na–Mg–HCO₃, Na–Ca–Mg–HCO₃, Ca–Mg–Na–HCO₃–Cl and Na–Ca–HCO₃–SO₄ types. A positive high correlation (r ² = 0.928) between Na and Cl suggests that the salinity of groundwater is due to intermixing of two or more groundwater bodies with different hydrochemical compositions. Barring a few locations, most of the groundwater samples are suitable for irrigation uses. Chemical fertilizers, sugar factories and anthropogenic activities are contributing to the sulphate and chloride concentrations in the groundwater of the study area. Overexploitation of aquifers induced multi componential mixing of groundwater with agricultural return flow waters is responsible for generating groundwater of various compositions in its lateral extent.     

Effects of the Herbicide Diuron on Cordgrass (<Emphasis Type="Italic">Spartina foliosa</Emphasis>) Reflectance and Photosynthetic Parameters

Early indicators of salt marsh plant stress are needed to detect stress before it is manifested as changes in biomass and coverage. We explored a variety of leaf-level spectral reflectance and fluorescence variables as indicators of stress in response to the herbicide diuron. Diuron, a Photosystem II inhibitor, is heavily used in areas adjacent to estuaries, but its ecological effects are just beginning to be recognized. In a greenhouse experiment, we exposed Spartina foliosa, the native cordgrass in California salt marshes, to two levels of diuron. After plant exposure to diuron for 28 days, all spectral reflectance indices and virtually all fluorescence parameters indicated reduced pigment and photosynthetic function, verified as reduced CO₂ assimilation. Diuron exposure was not evident, however, in plant morphometry, indicating that reflectance and fluorescence were effective indicators of sub-lethal diuron exposure. Several indices (spectral reflectance index ARI and fluorescence parameters EQY, Fo, and maximum rETR) were sensitive to diuron concentration. In field trials, most of the indices as well as biomass, % cover, and canopy height varied predictably and significantly across a pesticide gradient. In the field, ARI and Fo regressed most significantly and strongly with pesticide levels. The responses of ARI and Fo in both the laboratory and the field make these indices promising as sensitive, rapid, non-destructive indicators of responses of S. foliosa to herbicides in the field. These techniques are employed in remote sensing and could potentially provide a link between landscapes of stressed vegetation and the causative stressor(s), which is crucial for effective regulation of pollution.     

Kinetics of nitroreductase-mediated phytotransformation of TNT in vetiver grass

The effectiveness of vetiver grass in removing 2,4,6-trinitrotoluene (TNT) and the involvement of nitroreductase (NR) enzyme in TNT degradation in vetiver has been documented in our earlier studies. The present study was designed to optimize the parameters influencing NR enzyme-mediated TNT transformation in vetiver. The current study is the first report of detailed kinetic examination of NR enzyme induced by TNT in vetiver. Results show that NR activity in vetiver root increased with exposure time as well as with initial TNT concentration, showing a first-order reaction kinetics at lower and a second-order reaction kinetics at higher TNT concentrations. Nitroreductase activity was higher in shoot compared to root in all TNT treatments. Increasing concentration of TNT resulted in a significant increase in the NR activity in shoot. Very high increase in the shoot NR activity indicates a faster root-to-shoot translocation of TNT. The optimum range of the factors influencing NR-mediated TNT transformation and the kinetic parameters were determined, which will be crucial for the application of vetiver for phytoremediation of TNT-contaminated systems.     

Continuous wavelet transforms of spectral decomposition analyses for fluvial reservoir characterization of Miano Gas Field,Indus Platform,Pakistan

Fluvial depositional systems constitute diverse host for the hydrocarbons all over the globe. Nevertheless, predicting the hydrocarbon sands within these assorted sand systems is a challenge for the prospect generation. We apply the continuous wavelet transform of spectral decomposition technique to a 3D seismic data of the Miano Gas Field in the Indus Platform, Pakistan. Full spectrum seismic attributes like the amplitude and root mean square (RMS) detect the reservoir sands down to a restricted reservoir compartment. Nonetheless, the continuous wavelet transforms can be advantageous in imaging and enactment of these clastic reservoirs within the whole reservoir zone. Rock physics reveal high-quality reservoir with an average porosity ～25% together with the discrimination of lithology/fluids, signifying the bright chances for ascertaining the potential stratigraphic reservoirs.     

Ptygmatic structures: an analysis and review

Buckling of an isolated elastic-plastic layer embedded in a Newtonian viscous matrix has been studied and the generation of ptygmatic folding leading ultimately to clod and fragmentation at the crests as well as along the limbs has been discussed. The cause of formation of some of the uncommon ptygmatic structures has also been evaluated along with a review of the different postulates.

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Zusammenfassung Im Experiment wird die Aufwölbung einer isolierten, elastisch-plastisch Lage in einer viscosen Newton'schen Matrix simuliert. Es entstehen hierbei ptygmatische Falten, die im Endstadium sowohl in den Scheiteln als auch auf den Flanken zerscheren und zerbrechen. Es kann dabei auch die Entstehung ungewöhnlicher ptygmatischer Strukturen studiert werden.

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Résumé Le gondolement d'une couche de plastique élastique enrobée dans une matrice visqueuse newtonienne montre que la formation de plis ptygmatiques conduit finalement à des loupes et des cassures dans les charnières comme aussi le long des flancs. La cause de la formation de certaines structures ptygmatiques a été également considérée sur la base des différents postulats.

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- Newton'a. , c . .

     

Palaeoclimate,stratigraphy and prehistory in north and west Rajasthan

Quaternary formations in western Rajasthan are of fluvial, locustrinal and aeolian origins. Fossil gravel ridge of Jayal in Nagaur District is one of the earliest quaternary formations so far recorded in the region. A rich lower palaeolithic habitation-cum-workshop site has been discovered in association with the gravel ridge. Multiple evidence for climatic change in the area during the quaternary period is discussed.     

Ground motion amplification by cylindrical valleys embedded in a layered medium

The phenomenon of localized amplification of seismic waves due to subsurface irregularities has attracted the attention of seismologists and engineers for many years. In this paper we present a hybrid numerical method to investigate the ground motion amplification due to sedimentary basins. This method combines the integral representation and the finite element to solve the scattering problem due to an arbitrary cylindrical scatterer. A study is done on two shapes of valleys to show the effect of the angle of incidence, the incident wave type and the layering on the amplification of the surface displacement components by different valleys.     

Porosity prediction of lower cretaceous unconventional resource play,south Indus Basin,Pakistan, using the seismic spectral decomposition technique

Incised-valley shale systems are renowned as the fruitful exploration domains. However, the stratigraphic heterogeneity is significant, and thus, identifying the porous compartments within the thin-bedded and fractured shale system is one of the unconventional stratigraphic challenges. We present an innovative scheme for the exploration of the porous unconventional resources within the south Indus basin, Pakistan. The continuous wavelet transforms (CWT) exclusively detects the porous shales within the complete fractured system as compared to the full spectrum seismic data interpretation tool. The seismic amplitude, instantaneous frequency, and reflection strength tools show some tuning effects due to lithology and fluids. However, the tuning block of 28 Hz envelope sub-bands in conjunction with instantaneous phase tool accurately mark out the shale-plugged pinch out reservoirs. The synthetic wedge model based on the conventional seismic wavelet resolves the shale bed (incised-valley shale-filled lens) of about 23 m thickness, but shows limited imaging capability due to frequency band limitation for the porous shale locale. The acoustic impedance based on instantaneous spectral porosity modeling using the tuning volume of 28 Hz CWT has spectacularly resolved the thin-beds (gas shows) within the porosity range of 20 to 30%, which may have implications for future exploration of unconventional stratigraphic plays.