Geologic analysis of naturally fractured reservoirs. Chapter 2 naturally fractured reservoirs sciencedirect. Fundamentals of fractured reservoir engineering, volume 12. Petrophysical characterization of carbonate naturally.
They include reservoirs with low hydrocarbon recovery. It allows geologists and reservoir engineers to pragmatically understand the impact of fractures and their associated uncertainties. Fractured petroleum reservoirs make up more than 20% of the worlds oil and gas reserves saidi, 1983 but are considered to be among the most complicated classes of reservoirs. Prediction of naturally fractured reservoir performance using. Type 2 vs type 1 tectonic fractured reservoirs cenozoic asmari fields, zagros dual porosity reservoirs type 2 hydrocarbon storage capacity is given by micro and vuggy matrix porosity systems, whilst deliverability is provided by networks of fissures. Naturally fractured reservoirs are elusive systems to characterize and difficult to engineer and predict. Third eage workshop on naturally fractured reservoirs. Pdf naturally fractured reservoirs present a production paradox.
Naturally fractured reservoirs training course petroskills fr. Applications and limitations of geologic procedures and tools are discussed. Recovery efficiency in fractured reservoirs according to j. Fractured reservoirs distributed fractures, faults and folds have a profound impact on the geometry of sedimentary bodies and their physical behaviour, from mechanics to flow.
Well production heterogeneity is a characteristic of most naturally fractured reservoirs. In reasonable non fractured reservoirs, it is usually possible to estimate permeability, and hence productivity, but this is not always possible in fractured reservoirs. The behavior of naturally fractured reservoirs onepetro. Purchase fundamentals of fractured reservoir engineering, volume 12 1st edition. In reasonable nonfractured reservoirs, it is usually possible to estimate permeability, and hence productivity, but this is not always possible in fractured reservoirs. The influence of fracture closure from petroleum production. When evaluating a fractured reservoir, the analyst must follow these steps determine the origin of the fracture system found or the type of fracture system that is being explored for based on geometric characteristics of the fractures, their distribution in three dimensions, and empirical models of fracture system genesis. Pemex, tomatla 25 colonia santo domingo delegacion coyoacan c. Modeling flow behavior in naturally fractured reservoirs. Naturally fractured reservoir characterization digital edition. Combining outcrop studies and numerical modelling tools we improve our ability to predict mechanic and flow behaviour of. Naturally fractured reservoirs aguilera, roberto on. Numerical results show that d, the ratio of matrix system permeability to. This course covers geologic concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs.
In addition, fracturebearing experimental rock samples are difficult to obtain and prepare. An idealized model has been developed for the purpose of studying the characteristic. Wayne narr is a structural geologist with interest in characterization and modeling of naturally fractured reservoirs. Fractured petroleum reservoirs make up more than 20% of the worlds oil and gas reserves saidi, 1983 but are considered to be. Emphasis will be given to basement reservoirs and their. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs. Naturally fractured reservoirs contain a major part of the worlds remaining hydrocarbon reserves but their successful characterisation and. The term naturally fractured reservoirs generally refers to reservoirs where the fractures have an effect on the fluid flow nelson, 1985.
The focus is on understanding fractures in a reservoir how to determine whether fractures are important to hydrocarbon producibility, and if so. The need for an interpretational model that is valid for fractured reservoirs in general, was evident. The workshop covers all the aspects of modeling fractured reservoirs. Oil recovery in fractured reservoirs arne graue, robert w. Fracaflow is the only package available on the market to provide all the necessary tools to assess fractured reservoirs, from secondary porosity assessment to permeability computation. Gilman, page 5 of 35 however, fracture flow could be used to ones advantage as in gasinduced gravity drainage of. Although both the presence of fractures and the presence of a reservoir can be determined from logs, a production test will be needed to determine whether economic production. Typical type1 naturally fractured reservoirs are the amal field in libya, edison. The following diagrams and points are based on an example from the central. Most carbonate reservoirs are naturally fractured and contain fractures that can range from isolated microscopic fissures to kilometerwide collections called. Purchase geologic analysis of naturally fractured reservoirs 2nd edition. Therefore, in the present study, reservoir rock stress. Fracture porosity of naturally fractured reservoirs onepetro. In type 1 reservoirs, fractures provide the essential reservoir storage capacity and permeability.
Get pdf abstract an idealized model has been developed for the purpose of studying the characteristic behavior of a permeable medium which contains regions which contribute significantly to the pore volume of the system hut contribute negligibly to the flow capacity. Crains petrophysical handbook fractured reservoir basics. Pressure response in a naturally fractured reservoir showing ideal dual porosity behavior. Fractured reservoirs also tend to have higher anisotropy, which is seen as large variation in k90 vs. An alternative analytical solution to the system of equations for fluid flow through a doubleporosity medium with a boundary condition of an equipotential surface is given in this paper. The original idealized model assumes that the fracture is. It requires a thorough understanding of matrix flow characteristics, fracture network connectivity and fracture matrix interaction. Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis mehdi e. Pdf the nature of naturally fractured reservoirs researchgate. Get pdf abstract an idealized model has been developed for the purpose of studying the characteristic behavior of a permeable medium which contains regions which contribute significantly to the pore volume of the system hut contribute negligibly to the flow. The solution is straightforward, and involves only ordinary bessel functions. Fractures and open ings of large size form vugs and interconnected channels, whereas the fine cracks form blocksy5. Crains petrophysical handbook fracture porosity aperture. Artificial neural network ann to estimate reservoir.
Characterization of fracture networks is a pragmatic process that relies heavily on experience and empiricism and very little to. This article is based on crains analyzing fractured reservoirs by e. Practical aspects of simulation of fractured reservoirs 08012003 2003, james r. In fractured reservoirs viscous displacement often fails. Theoretical pressure derivative curves, generated by the sthefest numerical laplace inverse algorithm and belonged to a naturally fractured reservoir nfr with pseudo steady state pss inetrporosity flow, used to train the ann. With a few exceptions, the rock matrix is generally responsible for the storage capacity of a reservoir whilst existing layerbound and crosslayer fracture sets. Calculate porosity partitioning coefficient of a naturally fractured reservoir calculate storage capacity and interporosity flow factor analyze well tests in naturally fractured reservoirs assess reservoir performance of horizontal wells in nfr use mbe to analyze impact of pressure depletion on recovery dr. Stress sensitivity in naturally fractured reservoirs.
Castagna1 1university of houston 2schlumberger and 3delta geophysics received march 2012, revision accepted september 2012 abstract. Abstract due to complexity associated to petrophysical characterization of the porosity in naturally fractured reservoirs, a methodology to discretize it in four main systems was developed. He held the title of senior research consultant for chevron energy technology company where he worked for 27 years on an array of international projects that included reservoir structural geology studies, consulting, technology development, training, and exploration. Pdf characterization of naturally fractured reservoirs. It is important to establish some basic criteria for recognizing when fractures are an important element in reservoir performance and to recognize the nature and performance characteristics of a naturally fractured reservoir.
Recognizing naturally fractured reservoirs petrowiki. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturally fractured reservoirs. Geologic analysis of naturally fractured reservoirs nelson, ronald on. The behavior of naturally fractured reservoirs including. Naturally fractured reservoirs have been classified according to the relative contribution of the matrix and fractures to the total fluid production. The challenge of estimating recovery from naturally fractured. The behavior of naturally fractured reservoirs joi%warren p, j, rqot members aime abstract an idealized model has been developed for the purpose of studying the characteristic behavioroja permeable medium which contains regions which contribute sigizificantly to tbe pore volume o. The simulation of naturally fractured reservoirs nfrs has always been a challenging topic from the time of their discovery.
Determining how the fractures originated provides us with important clues for the areal and vertical distribution of fractures as well as a likely reservoir recovery. Geologic analysis of naturally fractured reservoirs 2nd edition. Controls on recovery factor in fractured reservoirs. Reservoir characterization of fractured reservoirs in western. Storativity and interporosity flow parameters, and c. Well test characteristics and analysis methods apparent single porosity homogeneous model. Reservoir characterization for naturally fractured reservoirs. Well test analysis for naturally fractured reservoirs.
The high permeabilities of the fractures effectively short circuits the matrix blocks, making it difficult to establish sufficiently high pressure gradients to allow effective viscous displacement of the oil in the matrix a new important effect comes into play imbibition. Core description in the authors experience, based on a number of studies in western canada, there is a typical core permeability vs. Moe and thomas bogno department of physics, university of bergen, norway abstract visualization of the effects of various wettability conditions on oil recovery in fractured reservoirs is demonstrated in twodimensional insitu imaging experiments in large blocks of. Nelson 1 identifies four types of naturally fractured reservoirs. The challenge of estimating recovery from naturally. Participants will gain knowledge of how fractured reservoirs differ from conventional reservoirs, and how to approach their fractured reservoir projects in a systematic manner. Seismic characterization of naturally fractured reservoirs. Generate reallife data sets fractured reservfractured. Most naturally fractured reservoirs i am familiar with are characterized by low matrix porosities less than 10% and low matrix permeabilities less than 1 md. Sun spe 84590 data obtained on the 100 fractured reservoirs examined in this study indicate that overall, their ultimate recoveries are somewhat lower than those of many conventional reservoirs, but they still compare favorably with some conventional reservoir types. Geologic and engineering aspects of naturally fractured. The use of the dualporosity approach for the modeling of naturally fractured reservoirs has become widely accepted in the oil industry. Naturally fractured reservoirs pdf free download epdf.
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