Seismic characterization of naturally fractured reservoirs. This large pressure drop causes the fracture pore volume, therefore fracture porosity, to increase. Evaluation of water coning phenomenon in naturally fractured. Well production heterogeneity is a characteristic of most naturally fractured reservoirs. Fracture propagation in naturally fractured reservoirs. Reservoir characterization of fractured reservoirs in. Because they must be incorporate into the numerical model of simulation the results of the petrophysical characterization, it is conceptualized like a model of double porosity. Simulation of naturally fractured reservoirs with simbestii. Recovery the rate of pressure decline per unit of oil produced the absence of transition zones in a fractured reservoir pressure drop around a producing wellbore in a fractured reservoir is very low. Spe member price usd 45 naturally fractured reservoirs present unique and specialized challenges to hydrocarbon extraction.
Fractures and open ings of large size form vugs and interconnected channels, whereas the fine cracks form blocksy5. Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis mehdi e. Introduction the development of reservoir modeling and reservoir characterization for naturally fractured reservoirs nfrs has lagged behind simpler matrix flow dominated rock. Naturally fractured reservoir an overview sciencedirect topics. Problems related to naturally fractured reservoirs by adel. However, there are no panaceas, and tools and methods that work well in one reservoir can. A new method to estimate reserve in naturally fractured. Numerical results show that d, the ratio of matrix system permeability to. So talking about fractured reservoirs in general is not good enough. Spe 84590 presented at the spe technical conference and exhibition held in colorado, 5 to 8 october. The behavior of naturally fractured reservoirs joi%warren p, j, rqot members aime abstract.
This behavior is observed particularly in reservoir where matrix porosity is. A naturally fractured reservoir nfr has two different porosities and permeability. Naturally fractured reservoir characterization seeks to confront many of these challenges by providing an introduction to the engineering and geological character of naturally fractured reservoirs. Fractured reservoirs are not isotropic, and models of fluid movement must account for. Gilman, page 4 of 35 with all these issues, there may appear to. Natural fractures, which are part of the secondary porosity, can be classified as tectonic, regional, and diagenetic aguilera, 1988. Naturally fractured reservoirs nfrs have been studied intensively for several decades in the geologic and engineering fields and recently, two new approaches have been proposed to address the problem of transient pressure testing in naturally fractured reservoirs. The behavior of naturally fractured reservoirs including. They found that water coning takes place in fractured porous medium with permeability up to 10 darcys in both good and poorly cemented wells. In naturally fractured reservoirs, the derivative tends to show several stabilizations at different levels. 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. He has served as senior technical consultant and manager for marathon oil company in. Reservoir characterization for naturally fractured reservoirs.
Evaluation of water coning phenomenon in naturally. The challenge of estimating recovery from naturally. Geologic analysis of naturally fractured reservoirs. Naturally fractured reservoirs training course petroskills fr. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturally fractured reservoirs. A good development strategy for such reservoirs requires accurate information on reserve in place. Practical aspects of simulation of fractured reservoirs 08012003 2003, james 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. Pdf characterization of naturally fractured reservoirs. The purpose of this collection of 15 papers is to introduce the subject of naturally fractured reservoir characterization to engineers interested in gaining a basic overview of the technology and its. Castagna1 1university of houston 2schlumberger and 3delta geophysics received march 2012, revision accepted september 2012. The focus is on understanding fractures in a reservoir how to. Oil recovery in fractured reservoirs arne graue, robert w. Characterization of naturally fractured reservoirs digital. 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. Depending on the selection of the radial flow regime, different well and reservoir models may be possible. Naturally fractured reservoirs present a production paradox.
The purpose of this collection of 15 papers is to introduce the subject of naturally fractured reservoir characterization to engineers interested in gaining a basic overview of the technology and its applications. Studies in naturally fractured reservoirs for improved eor. Pdf permeabilities and skins in naturally fractured reservoirs. They include reservoirs with low hydrocarbon recovery. This publication deals exclusively with naturally fractured reservoirs, and includes many subjects usually treated in separate volumes. Recovery factors and reserves in naturally fractured reservoirs. Textbook series natural fractured reservoir engineering. Pressure response in a naturally fractured reservoir showing ideal dual porosity behavior. Hydraulic fracturing in tight gas and shale gas reservoirs is an essential stimulation technique for production enhancement. Formation evaluation of naturally fractured reservoirs. Natural fractures exist practically in all reservoirs, dividing the reservoir rock in pieces, called matrix blocks.
The most difficult problem after finding basement rock reservoirs is to evaluate. The best known attempts at simple continuum models are the dual porosity approaches for naturally fractured reservoirs aguilera, 1980. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs. Because they must be incorporate into the numerical model of simulation the results of the petrophysical characterization, it is conceptualized like a. For these reservoir characteristics it is difficult to place a reasonable certainty of volumetric estimates of original hydrocarbonsinplace and reserves.
Formation evaluation of naturally fractured reservoirs author roberto aguilera link web page. Fractured basement reservoir characterization for fracture. The focus is on understanding fractures in a reservoir how to determine whether fractures are important to hydrocarbon producibility, and if so. It is written for students, reservoir geologists, log. Behaviour of naturally fractured reservoirs re17 stephan k. Geologists, engineers, and petrophysicists concerned with hydrocarbon production from naturally fractured reservoirs will find this book a valuable tool for obtaining pertinent rock data to evaluate reserves and optimize well location and performance.
The use of the dualporosity approach for the modeling of naturally fractured reservoirs has become widely accepted in the oil industry. Jim has also been involved in training, consultation, and project work in reservoir engineering, reservoir simulation, naturally fractured reservoirs, horizontal wells and production uncertainty analysis. Well test analysis for fractured reservoir evaluation. The problem is reduced to solving an integral equation. Naturally fractured reservoirs 2nd edition free ebook download as pdf file.
Coauthor of fractured reservoir analysis, an aapg school. The production of fluids from naturally fractured reservoirs has. Well test analysis for naturally fractured reservoirs. Castagna1 1university of houston 2schlumberger and 3delta geophysics received march 2012, revision accepted september 2012 abstract. Petrophysical characterization of carbonate naturally. Controls on recovery factor in fractured reservoirs. 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. They often comprise high permeable, low storage volume fractures, and tight, high storage volume matrix blocks. Fractured reservoirs are not isotropic, and models of fluid movement must account for such heterogeneity. In naturallyfractured reservoirs, the derivative tends to show several stabilizations at different levels. Naturally fractured reservoirs have been classified according to the relative contribution of the matrix and fractures to the total fluid production. How dual porosity reservoirs are modeled with modern numerical simulators and simulation exercises will. Directional permeability has important applications to drawdown andor injection with regard to well placement, and eor. Naturally fractured reservoirs fluid flow in petroleum.
The original idealized model assumes that the fracture is the primary conduit for flow, whereas the matrix acts. The challenge of estimating recovery from naturally fractured. Field examples and case studies demonstrate the importance of integrated geologic and. Hydraulic fracturing in naturally fractured reservoirs and. Naturally fractured reservoirs nfrs are defined as reservoirs where fractures created by geological processes have a significant impact on the migration, storage, and extraction of hydrocarbons table 5. Geologic and engineering aspects of naturally fractured. Wayne narr is a structural geologist with interest in characterization and modeling of naturally fractured reservoirs. The solution is straightforward, and involves only ordinary bessel functions. Naturally fractured reservoirs are elusive systems to characterize and difficult to engineer and predict. Roberto aguilera, 1995, naturally fractured reservoirs 2nd edition. The behavior of naturally fractured reservoirs onepetro. This course will cover the oil recovery mechanisms in fractured reservoirs, which undergo the waterflood or gas cap expansion and gas injection. A reservoir simulation approach for modeling of naturally. 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.
However, traditional rate transient analysis, a reserve estimation technique, is not suited for naturally fractured reservoirs. There are many logging tools and many methods that can be used for detection and evaluation of naturally fractured reservoirs see aquilera. Naturally fractured reservoirs pdf free download epdf. The porosity of the matrix is the primary porosity, whereas secondary porosity is represented by fractures channels. Therefore, naturally fractured reservoirs are termed as dual.
Chapter 1 deals with geologic aspects of naturally fractured reservoirs, reasons for generations of fractures including tectonic, regional, contractio nal and surfacerelated fra ctures, migration and accumulation of petr61eum, direct and indirect sources of information. Fracture porosity of naturally fractured reservoirs onepetro. On the other hand, they represent some of the largest, most productive reservoirs on earth. The pressure buiidup performance has been examined insomedetait.
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. 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. Pdf advances in the study of naturally fractured hydrocarbon. Naturally fractured reservoirs nfrs are defined as reservoirs where.
In naturally fractured reservoirs, the matrix pore volume, therefore the matrix porosity is reduced as a result of large reservoir pressure drop due to oil production. Fractured basement reservoirs differ from other types of naturally fractured reservoirs in that they are generally considered to have no primary porosity le van hung et al. They are also notorious for early gas or water breakthrough. It is written for students, reservoir geologists, log analysts and petroleum engineers. 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. Characterization of naturally fractured reservoirs article pdf available in spe reprint series spe 69538 march 2001 with 1,474 reads how we measure reads. Often, hydraulic fracturing induces fracture patterns that are more complex than the planar geometry that has been assumed in the past models. Purchase well test analysis for fractured reservoir evaluation, volume 27 1st edition. Introduction conventional reservoir engineering techniques and naturally fractured reservoirs do not mix well. The same conclusion was reached earlier by odeh 1965 who studied several fractured reservoirs. Applications and limitations of geologic and engineering procedures and tools are discussed. Recognizing naturally fractured reservoirs petrowiki. Pdf though matrix and secondary porosity permeabilities of a naturally fractured reservoir are. In fractured reservoirs viscous displacement often fails.
Naturally fractured reservoirs aguilera, roberto on. Naturally fractured reservoirs constitute a substantial percentage of remaining hydrocarbon resources. 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. Aguilera5 classified the naturally fractured reservoirs in types a, b and c.
295 1147 53 224 649 825 1215 1151 814 1389 575 587 1493 547 1435 1107 192 461 1110 445 71 155 880 1233 295 65 955 1086 94 1481 395 1043 884 207 709 229 951 1230