In general, it may be concluded that the analysis of a naturally fractured reservoir from pressure transient data relies considerably on the degree and the type of heterogeneity of the system. Geologic analysis of naturally fractured reservoirs 2nd edition. This webpage version is the ed intellectual property of the author. Geomechanical response of fractured reservoirs mdpi. Petrographic and organicgeochemical analyses on bitumen samples extracted from fractures and their host rock deliver insights into fracture genesis and. To describe flow in naturally fractured reservoirs, double pomsity model has been widely used. In this work, we investigate the pressure response in a naturally fractured reservoir. This article is published with open access at abstract water coning is a complex phenomenon observed in conventional and unconventional. Material properties used in the thermohydromechanical analysis of the naturally fractured reservoirs nfr. Fracture permeability, determined by transient pressure analysis pta versus. Naturally fractured reservoirs present a production paradox. Since all well logs are affected in one way or another by the presence of.
Castagna1 1university of houston 2schlumberger and 3delta geophysics received march 2012, revision accepted september 2012. A large proportion of the worlds oil and gas is produced from fractured reservoirs, with new discoveries continuing to be made and put into development. To investigate the boundary condition dependency of shape factor, the diffusivity equation is solved analytically in laplace domain for different depletion regimes in the fracture including. Simulation of naturally fractured reservoirs with simbestii. Formation evaluation of naturally fractured reservoirs. Naturally fractured reservoirs contain secondary or induced porosity in addition to their original primary porosity. Evaluation of water coning phenomenon in naturally fractured. Naturally fractured reservoirs training course petroskills fr. Borehole stability in naturally fractured reservoirs. Well test analysis of naturally fractured vuggy reservoirs with an analytical. Generally, nfr are modeled using euclidean geometry with homogeneous fracture systems that work well for some specific cases. A new procedure for history matching naturally fractured reservoirs.
This work examines flowrate decline behavior of naturally fractured reservoirs. The use of the dualporosity approach for the modeling of naturally fractured reservoirs has become widely accepted in the oil industry. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturally fractured reservoirs. This course will cover the oil recovery mechanisms in fractured reservoirs, which undergo the waterflood or gas cap expansion and gas injection. Characterization, evaluation and enhanced oil recovery in naturally fractured reservoirs. However, such reservoirs are often naturally fractured. The original idealized model assumes that the fracture is.
New pressure transient analysis methods for naturally. Evaluation of water coning phenomenon in naturally fractured oil reservoirs reda abdel azim1 received. The porosity of the matrix is the primary porosity, whereas secondary porosity is represented by fractures channels. In the industry for almost 30 years, nelson has authored numerous books and articles, the majority on fractured reservoirs, fault patterns, and fault propagation geometries in rifts, and in laboratory simulation of subsurface stress effects. Reservoir characterization for naturally fractured reservoirs.
The original idealized model assumes that the fracture is the primary conduit for flow, whereas the matrix acts as a group of distributed sources and sinks. Evaluation of water coning phenomenon in naturally. A reservoir simulation approach for modeling of naturally. An ideal theoretical model of a naturally fractured reservoir with a uniform fracture distribution, motivated by an earlier model by warren and root, has been developed. Many hydrocarbon reservoirs have sufficient porosity but low permeability for example, tight gas sands and coal beds. This conference will explore the many ways in which the geology of fractures is fundamental to the understanding of fluid flow in the subsurface, and hence to predicting and monitoring reservoir performance. 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. On the other hand, they represent some of the largest, most productive reservoirs on earth. Applications and limitations of geologic and engineering procedures and tools are discussed. Geologic analysis of naturally fractured reservoirs 2nd. Pdf characterization of naturally fractured reservoirs. The most difficult problem after finding basement rock reservoirs is to evaluate. Geologic analysis of naturally fractured reservoirs.
New analytical techniques for core analysis of fractured reservoirs f. Aug 24, 2001 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. Hydraulic fracturing in tight gas and shale gas reservoirs is an essential stimulation technique for production enhancement. The challenge of estimating recovery from naturally. Naturally fractured reservoirs are elusive systems to characterize and difficult to engineer and predict. Pressure transient analysis of naturally fractured.
Do not copy or distribute in any form without explicit permission. Naturally fractured reservoirs aguilera, roberto on. Dynamic characterization of naturally fractured reservoirs. Fractured basement reservoir characterization for fracture. They include reservoirs with low hydrocarbon recovery. The geological society of london the geology of fractured. 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. Naturally fractured reservoirs nfr contain over 60% of hydrocarbon reserves in the world. In addition, a multiphase fluid flow simulator using finite element technique has been generated and used to evaluate the recovery potential of the naturally fractured reservoir under different driving mechanisms and to assess the optimised generated subsurface fracture map by.
Chapter 2 naturally fractured reservoirs sciencedirect. The fracture patterns in these reservoirs can control flow and transport properties, and therefore, play an important role in drilling production wells. 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. They often comprise high permeable, low storage volume fractures, and tight, high storage volume matrix blocks. The nature of naturally fractured reservoirs schlumberger. Several conclusions were drawn for naturally fractured reservoirs with a dip angle from less than 10 to greater than 30. Purchase geologic analysis of naturally fractured reservoirs 2nd edition. Geologic analysis of naturally fractured reservoirs nelson, ronald on. Natural fractures are increasingly recognized as dominant permeability paths in many reservoirs. Apartado 76343 caracas venezuela 1070 abstract pressure transient solutions for constant rate production and transient rate analysis for con stant pressure production are presented for a naturally fractured reservoir. View naturally fractured reservoirs research papers on academia. Logs are the most readily available source of information, however they are seldomly used in a systematic manner for quantitative analysis of naturally fractured reservoirs.
Introduction the development of reservoir modeling and reservoir characterization for naturally fractured reservoirs nfrs has lagged behind simpler matrix flow dominated rock. Naturally fractured reservoirs differ from homogeneous reservoirs from many points of view. Naturally fractured reservoirs are heterogeneous porous media which consist of fractures and matrix blocks. Spe member price usd 45 naturally fractured reservoirs present unique and specialized challenges to hydrocarbon extraction. Well test analysis for naturally fractured reservoirs. Recognizing naturally fractured reservoirs petrowiki. The identification of this new flow regime provides methods for preparing a complete analysis of pressure data obtained from naturally fractured reservoirs. The minimum downhole pressures required to maintain borehole stability under different natural fracture occurrences were calculated by using the data from a well in the tazhong. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs.
Submitted to the office of graduate and professional studies of. The chapter explains reservoir description, production from a fractured reservoir, welltest analysis, and comparison of existing models for welltest interpretation. Nelson emphasizes geological, petrophysical, and rock mechanics to complement other studies of the subject that use well logging. Unfortunately, there are few guidelines available for geologists and engineers characterizing and engineering naturally fractured reservoirs. The following diagrams and points are based on an example from the central. Naturally fractured reservoirs present unique and specialized challenges to hydrocarbon extraction. New analytical techniques for core analysis of fractured. Recovery efficiency in fractured reservoirs according to j. Characterization, evaluation and enhanced oil recovery in naturally fractured reservoirs natural fractures are increasingly recognized as dominant permeability paths in many reservoirs. Naturally fractured reservoirs have received considerable attention in the recent decades since more than half of the world oil reserves are found in this type of deposits. Based on the worldwide analogues database of over 100 naturally fractured basement and carbonate reservoirs, this masterclass is specifically developed to satisfy the increasing need of practical geosciencist to obtain technical knowledge of commercial hydrocarbon reservoirs in naturally fractured rocks, considered as marine exploration targets. Therefore, naturally fractured reservoirs are termed as dual. Geologic analysis of naturally fractured reservoirs ronald nelson 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. Reservoir characterization of fractured reservoirs in western.
Introduction, geologic analysis of naturally fractured. Prediction of naturally fractured reservoir performance using. Crains petrophysical handbook fractured reservoir basics. Borehole stability in naturally fractured reservoirs during. Hydraulic fracturing in naturally fractured reservoirs and. They are also notorious for early gas or water breakthrough. 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.
While, in naturally fractured reservoirs, the problem becomes more complicated due to the existence of two interacting porous media fracture and matrix which results in the formation of two cones. Important features of some mathematical models describing flow from matrix to fracture warren and root 1965 analytical model. Seismic characterization of naturally fractured reservoirs. Pressure transient analysis of naturally fractured reservoirs. Often, hydraulic fracturing induces fracture patterns that are more complex than the planar geometry that has been assumed in the past models. Fractured reservoirs also tend to have higher anisotropy, which is seen as large variation in k90 vs. A fractured reservoir is one in which naturally occurring fractures either have or are predicted to have a significant effect on reservoir fluid flow in the form of 1 increased reservoir permeability, 2 increased porosity, andor 3 increased permeability anisotropy. Geologic analysis of naturally fractured reservoirs, second edition volcanic reservoirs in petroleum exploration electron microscopy of shale hydrocarbon reservoirs aapg memoir 102 connecting the dots of a disconnected life. Pratt geological survey of canada calgary 330333 st. Naturally fractured reservoirs shape factor shahab gerami, fall 2010 1. Textbook series natural fractured reservoir engineering. Geologic and engineering aspects of naturally fractured. Geologic analysis of naturally fractured reservoirs ronald.
Controls on recovery factor in fractured reservoirs. Most nfr have heterogeneities occurring in a wide range of spatial scales. However, the rate response and producing capacity of these reservoirs have not received adequate attention. Geologic analysis of naturally fractured reservoirs ronald nelson on. It is expected for naturally occurring formations that the transition period of flow from fissures to matrix takes place during the radial flow regime. The focus is on understanding fractures in a reservoir how to. There are many logging tools and many methods that can be used for detection and evaluation of naturally fractured reservoirs see aquilera. Another model for predicting production of a dewatered fracture coal shale gas formation was presented by. 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. Characterization, evaluation and enhanced oil recovery in. Reservoir characterization of fractured reservoirs in. 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. Well test analysis for naturally fracrmred reservoirs giwanni da prat intevep, s. 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.
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. Pdf the behavior of naturally fractured reservoirs. However, there are no panaceas, and tools and methods that work well in one reservoir can fail miserably in the next one. In this thesis, two different 3d geomechanical models have been developed to simulate the interaction between the hydraulic fracture and the natural fractures, and to observe the impact of geomechanics on the potential microseismicity in these naturally fractured formations. The productivity and development of naturally fractured reservoirs are mainly affected by the fracture net configuration. This article is based on crains analyzing fractured reservoirs by e. Oil recovery in fractured reservoirs arne graue, robert w. The minimum downhole pressures required to maintain borehole stability under different natural fracture occurrences were calculated by using the data from a well in the tazhong central tarim area, tarim basin, west china. Based on the plane of weakness theory, a model for predicting borehole stability in fractured reservoirs under different stress states was estiblisted and the equations for solving borehole stability were developed. On the other hand, they represent some of the largest most productive reservoirs on earth.
Naturally fractured reservoirs research papers academia. How dual porosity reservoirs are modeled with modern numerical simulators and simulation exercises will. Prediction of naturally fractured reservoir performance. We also discuss a technique to construct permeability tensors from seismic, well log and well test analysis. This model consists of a finite circular reservoir with a centrally located well and two distinct porous. Geologic analysis of naturally fractured reservoirs ronald nelson on amazon. Spe 84590 presented at the spe technical conference and exhibition held in colorado, 5 to 8 october. The original idealized model assumes that the fracture is the primary conduit for flow, whereas the matrix acts.
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