Well production heterogeneity is a characteristic of most naturally fractured reservoirs. 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. Modeling flow behavior in 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. The workshop covers all the aspects of modeling fractured reservoirs. The focus is on understanding fractures in a reservoir how to determine whether fractures are important to hydrocarbon producibility, and if so. Pdf naturally fractured reservoirs present a production paradox. Recovery efficiency in fractured reservoirs according to j. Nelson 1 identifies four types of naturally fractured reservoirs. Textbook series natural fractured reservoir engineering. Practical aspects of simulation of fractured reservoirs 08012003 2003, james r. The influence of fracture closure from petroleum production. Most carbonate reservoirs are naturally fractured and contain fractures that can range from isolated microscopic fissures to kilometerwide collections called.
Geologic analysis of naturally fractured reservoirs. Participants will gain knowledge of how fractured reservoirs differ from conventional reservoirs, and how to approach their fractured reservoir projects in a systematic manner. Controls on recovery factor in 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. Wayne narr is a structural geologist with interest in characterization and modeling of naturally fractured reservoirs. It requires a thorough understanding of matrix flow characteristics, fracture network connectivity and fracture matrix interaction. 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. Pdf the nature of naturally fractured reservoirs researchgate. Reservoir characterization of fractured reservoirs in western. For these reservoir characteristics it is difficult to place a reasonable certainty of volumetric estimates of original hydrocarbonsinplace and reserves.
They include reservoirs with low hydrocarbon recovery. This course covers geologic concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs. 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. Storativity and interporosity flow parameters, and c. Naturally fractured reservoir characterization digital edition. In addition, fracturebearing experimental rock samples are difficult to obtain and prepare. The term naturally fractured reservoirs generally refers to reservoirs where the fractures have an effect on the fluid flow nelson, 1985. The following diagrams and points are based on an example from the central.
Third eage workshop on naturally fractured reservoirs. The challenge of estimating recovery from naturally. Fracture porosity of naturally fractured reservoirs onepetro. It allows geologists and reservoir engineers to pragmatically understand the impact of fractures and their associated uncertainties. Pressure response in a naturally fractured reservoir showing ideal dual porosity behavior. In reasonable nonfractured reservoirs, it is usually possible to estimate permeability, and hence productivity, but this is not always possible in fractured reservoirs. Geologic analysis of naturally fractured reservoirs nelson, ronald on. Numerical results show that d, the ratio of matrix system permeability to. This webpage version is the ed intellectual property of the author. Geologic analysis of naturally fractured reservoirs 2nd edition. Typical type1 naturally fractured reservoirs are the amal field in libya, edison.
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. The need for an interpretational model that is valid for fractured reservoirs in general, was evident. 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. The challenge of estimating recovery from naturally fractured. Pemex, tomatla 25 colonia santo domingo delegacion coyoacan c. 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. 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. Crains petrophysical handbook fracture porosity aperture.
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. Well test characteristics and analysis methods apparent single porosity homogeneous model. Naturally fractured reservoirs pdf free download epdf. Naturally fractured reservoirs have been classified according to the relative contribution of the matrix and fractures to the total fluid production. 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. Naturally fractured reservoirs are elusive systems to characterize and difficult to engineer and predict. Well test analysis for naturally fractured reservoirs.
Reservoir characterization for naturally fractured reservoirs. An idealized model has been developed for the purpose of studying the characteristic. Petrophysical characterization of carbonate naturally fractured reservoirs for use in dual porosity simulators hector pulido1,2, fernando samaniego1, guadalupe galiciamunoz1, jesus rivera r. 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. Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis mehdi e. 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. Prediction of naturally fractured reservoir performance using. 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. 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. Spe 84590 presented at the spe technical conference and exhibition held in colorado, 5 to 8 october. Stress sensitivity in naturally fractured reservoirs. Naturally fractured reservoirs training course petroskills fr. Petrophysical characterization of carbonate naturally. In fractured reservoirs viscous displacement often fails.
Purchase fundamentals of fractured reservoir engineering, volume 12 1st edition. 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. 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. Combining outcrop studies and numerical modelling tools we improve our ability to predict mechanic and flow behaviour of. 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.
The simulation of naturally fractured reservoirs nfrs has always been a challenging topic from the time of their discovery. The behavior of naturally fractured reservoirs onepetro. With a few exceptions, the rock matrix is generally responsible for the storage capacity of a reservoir whilst existing layerbound and crosslayer fracture sets. Purchase geologic analysis of naturally fractured reservoirs 2nd edition. Chapter 2 naturally fractured reservoirs sciencedirect. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs. In type 1 reservoirs, fractures provide the essential reservoir storage capacity and permeability.
Fractured petroleum reservoirs make up more than 20% of the worlds oil and gas reserves saidi, 1983 but are considered to be. Fundamentals of fractured reservoir engineering, volume 12. Castagna1 1university of houston 2schlumberger and 3delta geophysics received march 2012, revision accepted september 2012 abstract. The solution is straightforward, and involves only ordinary bessel functions.
Oil recovery in fractured reservoirs arne graue, robert w. The problem is reduced to solving an integral equation. The original idealized model assumes that the fracture is. Geologic and engineering aspects of naturally fractured. Recognizing naturally fractured reservoirs petrowiki. Emphasis will be given to basement reservoirs and their. Artificial neural network ann to estimate reservoir.
Generate reallife data sets fractured reservfractured. Fractured reservoirs also tend to have higher anisotropy, which is seen as large variation in k90 vs. Characterization of fracture networks is a pragmatic process that relies heavily on experience and empiricism and very little to. The use of the dualporosity approach for the modeling of naturally fractured reservoirs has become widely accepted in the oil industry. Applications and limitations of geologic procedures and tools are discussed. Naturally fractured reservoirs contain a major part of the worlds remaining hydrocarbon reserves but their successful characterisation and. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturally fractured reservoirs. Well test analysis for naturallyfractured reservoirs stanfords. Artificial neural network ann is used to estimate reservoir parameters from well test data.
Core description in the authors experience, based on a number of studies in western canada, there is a typical core permeability vs. Maximizing economic recovery from naturally fractured reservoirs is a complex process. Gilman, page 5 of 35 however, fracture flow could be used to ones advantage as in gasinduced gravity drainage of. Seismic characterization of naturally fractured reservoirs. 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. Fractures and open ings of large size form vugs and interconnected channels, whereas the fine cracks form blocksy5. Crains petrophysical handbook fractured reservoir basics. This article is based on crains analyzing fractured reservoirs by e.
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