Tight Gas Reserviors

Río Negro avanza aceleradamente en la transformación de su economía en un enclave petrolero: de la mano del fracking los hidrocarburos han ganado importancia en el devenir provincial. Se supone que la radicación de inversiones y la expansión de la producción hidrocarburífera tendrán un efecto multiplicador sobre otros sectores de la economía, así como un impacto positivo en las finanzas provinciales.
Nuestra principal hipótesis de trabajo es que –tal como ilustran otras experiencias cercanas– la expansión del fracking pondrá en serios riesgos a distintas actividades productivas que son la base de una economía relativamente diversificada, y a partir de las cuales pueden proyectarse escenarios alternativos social y ambientalmente más sustentables.

The dissimilar metal joints of have been emerged as a structural material for various industrial applications which provides good combination of mechanical properties like strength, corrosion resistance with lower cost. Selections of joining process for such a material are difficult because of their physical and chemical properties. The stainless steel and mild steel dissimilar material joints are very common
structural applications joining of stainless steel and mild steel is very critical because of carbon precipitation and loss of chromium leads to increase in porosity affects the quality of joint leads deteriorate strength. In the present study, stainless steel of grades 202, 304, 310 and 316 were welded with
mild steel by Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding processes. The percentage dilutions of joints were calculated and tensile strength of dissimilar metal joints was investigated. The results were compared for different joints made by TIG and MIG welding processes and it was observed
that TIG welded dissimilar metal joints have better physical properties than MIG welded joints.

Tight gas is an important unconventional gas resource. It is also a basin centered gas reservoir which is associated with existing oilfields or bypassed zones and characterized by low in situ permeability of less than 0.6 mili Darcy. This evaluation initially started at San Juan basin in USA. There are about 40,000 tight gas wells producing from 1600 reservoirs in 900 fields whose estimated capacity is 3400 tcf. In India, the Cambay field holds about 413 bcf. amount of tight gas reserves. The layers of Tight Gas are attributed to commingled production and they are often layered and complex. Since the permeability is quite low, the reserves cannot be obtained profitably by vertical wells. As a result mostly horizontal wells and S-shaped wells are used for production of tight gas. Processes like Hydraulic Fracturing and Acidization are used to stimulate the well for better recovery. This technical paper aims at evaluation of tight gas reservoir in order to ameliorate the exploitation through different processes like material balance, volumetric method, transient pressure test, productivity index test and decline curve method along with the modern methods of interpretation of concentration pattern such as detailed Petrography by implementing XRD(X-ray diffraction) and SEM (Scanning Electron Microscope). Elemental Capture Spectroscopy along with Spectral Gamma Logging helps in detecting the distribution within wells. Tight Gas offers maximum recovery rate of 20%.

The focus of this paper is basically to document the application of geophysicist tools for prospect evaluation and characterization on unconventional reservoir which is tight gas reservoir. A methodology and workflow developed is described associated with the case study specifically from Alberta, Canada and Jonah (Pinedale gas field), Wyoming. Generally the challenge in analyse unconventional reservoir due to several aspects i.e. high pressure zone, thin bedding, reservoir fractures, optimal area for drill, have been discussed and can be avoided by sensible choice of geophysicist tools i.e. AVO, Stochastic inversion, Vp/Vs ratio, low frequency modelling.

many countries in the world are producing there Gas from tight reservoir as the conventional reservoirs are mostly explored. Pakistan contain more than 40TCF of tight gas reservoir that is proven in some areas of Pakistan. tight gas requires advance techniques for its production. In Pakistan production from tight reservoir is not common as it is not much economical. but in future gas will be produced from tight reservoir as unconventional reservoirs are the new future of oil and Gas Industries.

Reservoir characterization is a process that involves the integration of various qualities and quantities of data in a consistent way to describe the reservoir properties of interest in each well locations. Characterizing the reservoir is a process which describes various properties in reservoirs using all the available data to provide reliable reservoir models for accurate prediction of the performance of a reservoir. Reservoir characterization is of high importance because it plays an important role in the exploration and exploitation processes of the oil and gas industry and also gives room for optimum recovery of hydrocarbon at a minimized cost. A
play is one or more prospects that may define a profitable accumulation of undiscovered petroleum. Traditionally, a play is developed and evaluated without any particular petroleum system in mind. Wireline log data and 3D seismic data were analyzed to characterize the
reservoir with respect to its porosity, water saturation, the volume of shale and permeability in
“HARK” field. Reservoir “A” was delineated across four (4) wells-HARK_5, HARK_7,
HARK_10 and HARK_11. The average permeabilities observed across the wells range from
1108.945mD to 1767.393mD, while the effective porosity ranges from 21.4% to 23.9%. The
Hydrocarbon saturation ranges from 69.1% to 90.5% signifying the presence of a commercial
quantity of hydrocarbon accumulation. Oil-Water Contact has been encountered by the well at 3814 m TVD. The volumetric analysis carried out revealed that the volume of hydrocarbon in place for reservoir “A” was estimated at 308 bb/STB. The outcome of this project is a notable approach in characterizing reservoirs and hydrocarbon producibility of the reservoir.

Hydraulic cracking is a way to provide stimulation to the reservoir to increase productivity. Low permeability reservoir is a right target for hydraulic fracturing. Fracturing activity requires economic consideration factors such as costs and revenues that will be earned. Selection of the proper design is the key to success this fracturing job.
In this study, we sensitivity varying lengths of fractures to conduct their effects on the net present value (NPV). A methodology was developed to determine the effect of the length of the fracture caused by the design of the to NPV and production period. Various information is also used to support and run this study. Reservoir property information, the configuration of the well, the mechanics of fracturing, fracture geometry model selection and economic data became the basis for calculating in this study.
From the simulation results using a simulator, the optimum design of fracturing can be determined by considering the best NPV of each fracture length. Best design fracture length is the length of cracks that can provide the greatest NPV. Other parameters such as recovery increment and production period can be determined through the results of this simulation.

Keywords: hydraulic fracturing, design optimization, low permeability

Mr. Campbell and Dr. Conca provided one of the 10 summaries for energy resource commodities on uranium, thorium, and rare earths (pp. 450-458). Other experts provided sections on geothermal, coal and unconventional energy resources, and on an analysis of energy economics and technology, all prepared by
committees of the Energy Minerals Division of the American Association of Petroleum Geologists. Unconventional energy resources, as used in this report, are those energy resources
that do not occur in discrete oil or gas reservoirs held in structural or stratigraphic traps in sedimentary basins. Such resources include coal-bed methane, oil shale, uranium and thorium
deposits and associated rare-earth elements of industrial interest, geothermal, gas shale and liquids, tight gas sands, gas hydrates, and bitumen and heavy oil. Current U.S. and global
research and development activities are summarized for each unconventional energy resource commodity in the topical sections of this report, followed by analysis of unconventional
energy economics and technology.

Natural tight reservoirs are networks with high connectivity but low porosity, in which fractal behaviors have been widely observed and proven to affect the transport property significantly. The objective of this study is to establish a mathematical model to describe fluid flow in fractal tight porous media. To address this problem, four fractal dimensions were used: the pore size fractal dimension D f , geometrical and hydraulic tortuosity fractal dimensions D sg and D s , and the fractal dimension D k characterizing the hydraulic diameter-number distribution. The relationship among these fractal dimensions was analyzed and D f was found equal to D k þ D sg. Then a unified model connecting the porosity and D f is deduced for arbitrary fractal tight porous media. Based on the scaling-invariant behaviors assumed, a fractal mathematical model is developed for the permeability estimation, which is fabricated only by fundamental and well-defined physical properties of D f ; D s , the scaling lacunarity P k , the range of the pore sizes, and the porosity of the fractal generator u 0. To validate the permeability model, we developed an algorithm to model fractal tight porous media according to the scaling-invariant topography of fractal objects based on Voronoi tessellations, and to simulate fluid flow in these complex networks by Lattice Boltzmann method (LBM) at pore scale. Numerical experiments indicate that the hydraulic tortuosity fractal dimension D s is approximately equal to 1.1. Consequently, the fractal mathematical model was quantitatively determined and its performance was verified by the LBM simulations. Finally, the fractal mathematical model was rearranged into a permeability-porosity form for practical applications.

Tight gas reservoirs are unconventional reservoir assets which have been the focus of major research in the petroleum industry owing to the global decline in conventional reservoirs. They are widely unlocked by creating hydraulic fractures in the formation to increase the flow capacity and productivity. The objective of this paper is to analyze different fracture geometries and their effect on tight gas production. The reservoir simulation model of the tight gas reservoir has been built with single porosity approach. A single vertical well with a single stage fracture has been used in the model to predict the behavior of fracture geometry. The major parameters of fracture geometry studied are fracture half-length, fracture width, and fracture height. Four sensitivities are run over different fracture geometry that is constant height and constant width, constant height and changing width, changing height and constant width, and changing height and changing width, while increasing the fracture half-length from 100 ft to 500 ft in each case. Sensitivity analysis exhibited that keeping the hydraulic fracture at constant height and constant width while increasing the fracture half-length resulted in enhanced tight gas productivity i.e. 11.63%, 14.14%, 16.06%, 17.48%, and 18.89% at hydraulic fracture half-lengths of 100 ft, 200 ft, 300 ft, 400 ft, and 500 ft, respectively, compared to other types of fracture geometry.

This paper is a field application of modem geostatistical reservoir characterization to a complex, low-permeability gas reservoir. Multiwell history matching with this approach is shown to be significantly better than those done with historical approaches. Important opportunities for additional drilling were identified; however, these additional infilllocations required significantly lower well costs to be commercial.

El texto aborda distintas aristas del conflicto en torno a la producción de hidrocarburos no convencionales en el yacimiento Vaca Muerta, en Argentina. Una de las disputas centrales tiene como protagonistas a las comunidades mapuche, las empresas y el Estado provincial y nacional. El trabajo analiza la resistencia que desarrolla la comunidad mapuche de Campo Maripe que reclama la propiedad de su territorio ancestral ubicado en el corazón de la explotación de los recursos no convencionales, en la provincia de Neuquén, distinguiendo cómo el Estado y los empresarios han recurrido a instrumentos judiciales y represivos para desalojar a la comunidad de estas tierras. Se partirá aquí del estudio del tramo final del juicio acontecido en la ciudad de Neuquén en 2019, donde fueron acusados de usurpación seis miem- bros de la comunidad Campo Maripe. La escena del juicio permite apreciar valoraciones, percepciones y acciones divergentes que se mo- vilizan entre los actores involucrados en el enfrentamiento con refer- encia al territorio, la naturaleza, y la mirada sobre el otro. Desde una perspectiva de análisis sociológico y cualitativo, se aporta a una re- flexión sobre la modalidad que adoptan los conflictos sociales en tor- no al fracking en Vaca Muerta, los motivos de las resistencias y algu- nas de las estrategias que adopta el capital para proseguir con la ex- plotación de los bienes de la naturaleza para la producción de energía.


Abstract
The text focuses on different aspects of the conflict surrounding the production of unconventional hydrocarbons in Vaca Muerta, Argen- tina. One of the central disputes has as protagonists the Mapuche community, the provincial and national state, and companies. The work analyzes the resistance developed by the Mapuche community of Campo Maripe, which claims ownership of its ancestral territory located in the heart of the exploitation of unconventional resources, in the Province of Neuquen, distinguishing how the State and busi- nessmen have resorted to judicial and repressive instruments to evict the community from these lands. It will start from the study of the final stretch of the usurpation trial that occurred in the provincial city in 2019, where the accused were the six members of community of Campo Maripe. The trial thus acts as a prism that allows us to appre- ciate divergent valuations, perceptions and actions that are mobilized between the actors involved in the confrontation with reference to the territory, nature, and the gaze on the other. From a sociologic and qualitative analysis perspective, it contributes to a reflection on the modality adopted by social conflicts around fracking in Vaca Muerta, the reasons for the resistance, and on some of the strategies that cap- ital adopts to continue exploiting the assets of nature at the current stage of energy production.

La producción de hidrocarburos en la provincia del Neuquén comenzó en el año 1918 y a partir de ese momento se ha producido gas y petróleo de reservorios convencionales correspondientes a las diferentes formaciones que integran la columna de la Cuenca Neuquina.
El aumento en la demanda energética de los últimos años ha provocado un cambio de paradigma que llevo a considerar nuevas técnicas para la exploración y desarrollo de los hidrocarburos y de esta manera comenzaron a adquirir mayor relevancia los reservorios en lutitas y areniscas compactas (shale y tight). Estos reservorios, denominados como No Convencionales, están integrados por rocas que contienen gas y/o petróleo  y para que su extracción sea económicamente rentable es  necesario métodos de estimulación a través de fracturas hidráulicas en etapas.
La puesta en producción de este tipo de reservorio ha impactado de manera positiva en la producción y reservas de gas y petróleo de la provincia de Neuquén, atenuando la declinación de la producción y reservas de los reservorios convencionales.
El presente trabajo tiene como finalidad realizar una caracterización geológica de los principales reservorios tight y de baja permeabilidad que se encuentran en producción y proponer una distribución areal en base a los antecedentes disponibles.

Numerical simulation results for two Cotton Valley wells are presented. A three-dimensional, radial, dry-gas model was used to simulate multiple-layer, very low permeability reservoirs. Examples of inputs and modifications to the model from various tests and techniques are presented. These include the use of radioactive sand tracers during fracturing to determine fracture height, pressure buildup analysis, production logging, well log analysis, core analysis, and detailed geological mapping. The final permeabilities used in the model were much lower than those estimated from core analysis. Both conventional methods and more recent type-curve methods were used to analyze long-term pressure buildups and drawdowns to estimate fracture length, fracture conductivity , and formation permeabil ity. Indicated reserves from the simulation study are higher than presimulation estimates. Infill drilling will be required to drain this very low permeability reservoir adequately and efficiently. Information derived from individual well simulations is being used to optimize well spacing and fracture length.

Well spacing and hydraulic fracture treatment designs are the two most important operator-controlled factors in the development of low permeability gas reservoirs. Prior studies of optimization of fracture length and well spacing assumed homogeneous permeabil-ity, porosity, thickness, etc. This analysis illustrates the importance of understanding spatial variability of permeability and permeabil-ity anisotropy. Geostatistical techniques are incorporated with economic and reservoir modelling to show the quantitative value of reservoir description in tight gas reservoirs.

Hydraulic fracturing, is a promising stimulation technique which is also known as hydrofracturing, hydrofracking and fracking. During the hydraulic fracturing (HF), the rock is cracked, i.e., fractured, by a high pressure injection of a fluid which is known as fracturing fluid (FF). The FF is mainly water, carrying suspended sand or another type of proppants into the well to initiate fractures in the reservoir rock, and consequently, hydrocarbon and FF will move towards the well more easily through fractures. Hydro-fracturing is extensively used to increase the well productivity index, particularly in unconventional, tight and ultra-tight reservoirs. This expensive procedure, though, sometimes fails to meet expectations regarding the production enhancement. The leading explanations for this reduced performance is fracture clean-up inefficiency of the fracturing fluid (FF) that was primarily injected. In this study, a parametric investigation of FF clean-up effectiveness of fractures was performed with 143360 simulations (in 35 different sets) including injection, shut-in and production stages. Because of the vast number of simulation runs which was required to be implemented by a reservoir simulator, a computer code was developed and utilised to routinely read input data, implement the simulation runs and produce output data. In each set (which consists of 4096 runs), instantaneous impacts of twelve different parameters (fracture and matrix permeability (i.e., Kf and Km) and capillary pressure (Pc), end points and exponents of gas and FF in the Brooks-Corey relative permeability correlation in both fracture and matrix) were investigated. To sample the domain of variables and to study the results, full factorial experimental design (two-level FFS) and linear surface methodology explaining the dependency of the loss in gas production, compared to the case there is no loss (i.e., 100% clean-up) to the related parameters at different production stages were

La producción de hidrocarburos en la provincia del Neuquén comenzó en 1918 y, a partir de ese momento, se ha producido gas y petróleo de reservorios convencionales correspondientes a las diferentes formaciones que integran la columna de la Cuenca Neuquina. El aumento en la demanda energética de los últimos años ha provocado un cambio de paradigma que llevó a considerar nuevas técnicas para la exploración y el desarrollo de los hidrocarburos y de esta manera comenzaron a adquirir mayor relevancia los reservorios en lutitas y areniscas compactas (shale y tight). Estos reservorios, denominados No Convencionales, están integrados por rocas que contienen gas y/o petróleo y, para que su extracción sea económicamente rentable, es necesario aplicar métodos de estimulación a través de fracturas hidráulicas en etapas. La puesta en producción de este tipo de reservorio ha impactado de manera positiva en la producción y reservas de gas y petróleo de la provincia del Neuquén, atenuando la declinación de la producción y las reservas de los reservorios convencionales.

Depositional microfacies is an important influencing factor in the development of continental hydrocarbon-bearing reservoirs. However, the diagenetic responses to the depositional microfacies and their implications for reservoir quality variation remain enigmatic, which limits detailed reservoir description and prediction of the location of
high-quality reservoirs. The tight continental reservoirs of the Yanchang Formation in the Ordos Basin were targeted with the aim of clarifying the differences in diagenetic, petrophysical and pore-structural characteristics of tight reservoirs within different microfacies. A multi-methodological approach, involving petrographic assessments, logging evaluations, physical property experiments, digital SEM imaging analyses, 3D micro-CT imaging analysis, X-ray diffraction mineral identification and mercury intrusion experiments, was utilized to identify eight delta-front-lacustrine microfacies in this study. The results show that different microfacies reservoirs vary in compaction, dissolution, and clay mineral cementation. Interdistributary bays, shallow lacustrine mudstones, and semi-deep lacustrine mudstones that are rich in plastic clay and mica are those most likely to be affected by physical and chemical compaction. Reservoirs affected by meteoric water percolation and hydrocarbon generation, such as distributary channels, mouth bars and sheet sand reservoirs, are characterized by well-developed dissolution pores. Interbedded sand-mud deposits and lacustrine tidal incursions lead to strong ferrocalcite cementation into beach bar sandstones. The occurrence of authigenic chlorite and illite cements displays prominent microfacies zonation; kaolinitic and siliceous cementation show less variation than other diagenetic processes in different microfacies reservoirs. Finally, this study proposes two evaluation parameters: a pore connectivity index, E, and a pore structure evaluation parameter, A, to assist in clarification of the differences in reservoir quality resulting from the range of depositional microfacies. This provides guidelines for detailed reservoir description and grading evaluation.