Browsing by Author "Sunjay"

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An unconventional energy resources: Shale gas
(Offshore Mediterranean Conference (OMC), 2011) Sunjay; N. Kothari
With a view to energy security of the world ,unconventional energy resources-coalbed methane (CBM) , Methane GasHydrate,shale gas, tight gas,oil shale and heavy oilexploration and exploitation is pertinent task before geoscientist . Shale gas is natural gas from shale formations which acts as both the source and the reservoir for the natural gas. Each Shale gas reservoir has unique characteristics. Shale has low matrix permeability, so gas production in commercial quantities requires fractures to provide permeability . For a given matrix permeability and pressure, gas production are determined by the number and complexity of fractures created, their effective conductivity, and the ability to effectively reduce the pressure throughout the fracture network to initiate gas production. Understanding the relationship between fracture complexity, fracture conductivity, matrix permeability, and gas recovery is a fundamental challenge of shale-gas development. Shale gas reservoirs almost always have two different storage volumes(dual porosity) for hydrocarbons, the rock matrix and the natural fractures .Because of the plastic nature of shale formations, these natural fractures are generally closed due to the pressure of the overburden rock. Consequently, their very low, matrix permeability, usually on the order of hundreds of nanoDarcies (nD), makes unstimulated, conventional production impossible. Almost every well in a shale gas reservoir must be hydraulically stimulated (fractured) to achieve economical production. These hydraulic fracture treatments are believed to reactivate and reconnect the natural fracture matrix . Another key difference between conventional gas reservoirs and shale gas reservoirs is adsorbed gas. Adsorbed gas is gas molecules that are attached to the surface of the rock grains . The nature of the solid sorbent, temperature, and the rate of gas diffusion all affect the adsorption . Presently , the only method for accurately determining the adsorbed gas in a formation is through core sampling and analysis. Understanding the effects of adsorption on production data analysis increase the effectiveness of reservoir management in these challenging environments. They contain natural gas in both the pore spaces of the reservoir rock and on the surface of the rock grains themselves that is referred to as adsorbed gas .This is a complicated problem in that desorption time, desorption pressure, and volume of the adsorbed gas all play a role in how this gas affects the production of the total system. Adsorption can allow for significantly larger quantities of gas to be produced. Shale gas reservoirs present a unique problem for production data analysis. The effects of the adsorbed gas are not clearly understood except that it tends to increase production and ultimate recovery. The phenomena of gas storage and flow in shale gas sediments are a combination of different controlling processes. Gas flows through a network of pores with different diameters ranging from nanometres (nm = 10-9m) to micrometres (ìm = 10-6m). In shale gas systems, nanopores play two important roles. Petrophysical imaging employs first,second & third generation wavelet to delve deep into complex shale gas reservoir. Nanoscale gas flow in Shale gas sediments has scope to cope with research on drynanotechnology(smartfluid/nanofluid). © 2011 Offshore Mediterranean Conference. All Rights Reserved.
CO2 sequestration and cushion gas for geological storage
(2009) Sunjay
The scientific and technological knowledge needed to activate a CO2/CH4 exchange into natural gas hydrate fields is presented. This exchange should permit the recovery of methane from natural gas hydrate, concomitantly capturing an equimolar amount of CO2 in the same field, thus providing for a permanent geologic storage thereof. This presentation covers the methods of underground storage of natural gas; the types of underground natural gas storage facilities, such as depleted oil and gas reservoirs, salt caverns, mines, aquifers, and hard-rock caverns; and geosciences, gas storage geomechanics, and reservoir engineering. This is an abstract of a paper presented at the International Gas Union World Gas Conference (Buenos Aires, Argentina 10/5-9/2009).
Stratigraphy Using Wavelet Transform Analysis
(Springer, 2014) Sunjay
Wavelet (mathematical microscope) analysis of seismic data is useful for the precise subsurface imaging and interpretation of thin beds. Three-dimensional (3-D) seismic data interpretation for the subsurface imaging of thin-bed contourite systems is an important aspect of such research. The method enables the seismic expression of bottom current deposits to be distinguished from that of other related deep-water sediments (such as turbidites, hemipelagites, and debrites), and the information that can be derived from seismic data to be maximised. A wide variety of seismic facies are common in contourites, most of which are equally present in turbidite systems. Seismic facies associations that may be typical of contourites are yet to be defined. Seismic characteristics also depend very closely on the methods of seismic acquisition and processing. Sediment waves and channels are very common in both contourite and turbidite systems, and are not specifically diagnostic of either system. Slope deformation, sediment creep, and large-scale water-escape may cause a hummocky seismic facies that can be misinterpreted as sediment waves. The identification of hydrocarbon reservoirs from seismic data is a key issue in the oil industry. Texture segmentation of a 3-D seismic section with wavelet transform is employed for pattern recognition. Because of the segmentation, zones of different internal stratification are identified in the seismic section. This recognition is based on the comparison of 3-D seismic data with the reference patterns extracted from representative areas, characterized by different textures. In splicing 3-D seismic data, consistent processing is one of the key technologies because this has a large influence on imaging quality. The goal of seismic geomorphology is to look for and recognise geologically or geomorphologically meaningful patterns in plan view as well as in section view. Seismic geomorphology, the extraction of geomorphological insights using predominantly 3-D seismic data, is a rapidly evolving discipline that facilitates the study of the subsurface using plan-view images. Methods are being evolved for generating horizontal and flat slices, producing arbitrary traverses, performing wavelet attribute extractions and mapping, and rapidly analysing large, complex data volumes. A geological feature must have an expression that is scientifically reasonable in multiple dimensions. Analysis of section view images integrated with plan-view images represents the integration of seismic stratigraphy with seismic geomorphology. Pattern recognition, where the interpreter is able to recognize geologically significant features in plan view on 3-D seismic data, is critical to the seismic geomorphological approach. In addition, it is also essential to cross-reference plan-view images with section-view images, thus integrating the geomorphology with the stratigraphy. © 2014, Springer-Verlag Berlin Heidelberg.