The solution is straightforward, and involves only ordinary bessel functions. Naturally fractured reservoirs present a production paradox. The parameters range in percent due to matrix versus percent due to fracture. 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. This presentation is an introduction to naturally fractured reservoirs for subsurface students and professionals in the hydrocarbon industry who have little or no experience of them. Porosity distribution in fractured rocks after mcnaughton and garb56 another classification of fractured reservoirs is given by nelson61, which is based on percent of total porosity and permeability figure 1. Textbook series natural fractured reservoir engineering. Beware of water influx in naturally fractured gas reservoirs. Pdf naturally fractured reservoirs present a production paradox. On the other hand, they represent some of the largest most productive reservoirs on earth. Well test analysis for naturally fractured reservoirs. 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.
A reservoir simulation approach for modeling of naturally. Advances in the study of fractured reservoirs geological. Evaluation of water coning phenomenon in naturally. This article focuses on interpretation of well test data from wells completed in naturally fractured reservoirs. Applications and limitations of geologic and engineering procedures and tools are discussed. Fractured reservoirs have many more physical processes than single porosity reservoirs and. They are also notorious for early gas or water breakthrough. Gilman, page 4 of 35 with all these issues, there may appear to. Simulation is useful for combining all the components and generating production. The challenge of estimating recovery from naturally fractured reservoirs dr shane hattingh. Numerical results show that d, the ratio of matrix system permeability to. Naturally fractured reservoir characterization digital edition. Do not copy or distribute in any form without explicit permission.
Crains petrophysical handbook fractured reservoir basics. Reservoir characterization of fractured reservoirs in. 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. 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.
Pdf advances in the study of fractured reservoirs geological society of london special publications uploaded by jeffrey archer, their complex behaviour during production has traditionally proved difficult to predict causing a large degree of uncertainty in reservoir development the applied study of naturally fractured reservoirs. Two thirds of the oil reservoirs have recovery factors 20%, which is certainly high enough to be commercially attractive. Nelson 1 identifies four types of naturally fractured reservoirs. Naturally fractured reservoirs not only contain a significant share of the worlds. The problem is reduced to solving an integral equation. 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. Prediction of naturally fractured reservoir performance using. It is written for students, reservoir geologists, log. The shape and ra nge of the positive capillary pressure curve is dictated by the wettability. Simulation has limited use in the predevelopment stage for all types of reservoirs, but particularly for fractured reservoirs because.
Chapter 7 naturallyfractured carbonate reservoirs t. This publication deals exclusively with naturally fractured reservoirs, and includes many subjects usually treated in separate volumes. Conducting integrated reservoir studies in the quartzite. Transfers and typical features of numerical studies naturally fractured reservoirs contain a significant. Petrophysical characterization of carbonate naturally.
History matching, within the context of oil reservoir simulation, entails the adjustment of the geological description, or other model parameters, in order to achieve. 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. In fractured reservoirs viscous displacement often fails. Geologic analysis of naturally fractured reservoirs nelson, ronald on. Fractured basement reservoir characterization for fracture. Residual time sift values for six 3d seismic surveys. Characterizing fractured reservoirs acts as a group of distributed sources and. Modeling flow behavior in naturally fractured reservoirs.
Pdf use of fractured reservoir simulators can help reservoir engineers in the understanding of the main physical mechanisms and in the. Fractured reservoirs are not isotropic, and models of fluid movement must account for. Van golfracht introduction a carbonate reservoir is defined as being fractured only if a continuous network of various degrees of fracturing is distributed throughout the reservoir. This article is based on crains analyzing fractured reservoirs by e. Natural fractures exist practically in all reservoirs, dividing the reservoir rock in pieces, called matrix blocks. Typical type1 naturally fractured reservoirs are the amal field in libya, edison. Recovery is determined by physics and chemistry and the simulator cannot tell you what that is. 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. A new procedure for history matching 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. Intermediateadvanced course objectives and description this course is designed for geologists, geophysicists and reservoir engineers who are part of.
Combining this tool with acoustic, resistivity and temperature logs, we may obtain a. One structural framework and one surface for quartzite hamra top and bottom allover the surveys area after merge. This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturallyfractured reservoirs. 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. Well production heterogeneity is a characteristic of most naturally fractured reservoirs. Enhanced oil recovery in fractured reservoirs 91 capillary pressure curve, or more accurately, the positive part of the imbibition capillary pressure curve. Important features of some mathematical models describing flow from matrix to fracture warren and root 1965 analytical model. The 8 fractured gas reservoirs have an average ultimate recovery factor of 61%.
This course covers geologic and engineering concepts, methodology, and technology used to characterize, evaluate, and manage naturally fractured reservoirs. In order to predict productivity of multiple fractured horizontal well in fractured reservoir, flow models of reservoir and hydraulic fractures based on the volumetric source idealization are developed. 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. Chapter 2 naturally fractured reservoirs sciencedirect. For naturally fractured reservoirs, roberto aguilera 29 established an unsteady state water invasion model, taking the transient and pseudosteady interporosity. This article is published with open access at abstract water coning is a complex phenomenon observed in conventional and unconventional. The productivity and development of naturally fractured reservoirs are mainly affected by the fracture net configuration. Hydraulic fracturing of naturally fractured reservoirs. Fracture porosity of naturally fractured reservoirs onepetro. Gilman, page 4 of 35 with all these issues, there may appear to be little hope of getting a unique answer.
Because they must be incorporate into the numerical model of simulation the results of the petrophysical characterization, it is conceptualized like a. Evaluation of water coning phenomenon in naturally fractured oil reservoirs reda abdel azim1 received. Well test analysis for naturally fracrmred reservoirs giwanni da prat intevep, s. Studies in naturally fractured reservoirs for improved eor. The use of the dualporosity approach for the modeling of naturally fractured reservoirs has become widely accepted in the oil industry. Studies in naturally fractured reservoirs for improved eor scott p. Typical features of fractured reservoir numerical simulations are also. Naturally fractured reservoirs training course petroskills fr.
Bunger csiro earth science and resource engineering ian wark laboratory melbourne, victoria, 3168, australia, rob. Characterization and analysis of naturally fractured reservoirs is challenging for oil and gas companies around the world. In type 1 reservoirs, fractures provide the essential reservoir storage capacity and permeability. Evaluation of water coning phenomenon in naturally fractured. They include reservoirs with low hydrocarbon recovery. 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. Prediction of naturally fractured reservoir performance using novel integrated workflow reda abdel azim chemical and petroleum engineering department american university of ras al khaimah ras al khaimah, united arab emirates abstractgeneration of naturally fractured reservoir subsurface fracture maps and prediction its production potential.
Oil recovery in fractured reservoirs arne graue, robert w. Because of the presence of two distinct types of porous media, the assumption of homogeneous behavior is no longer valid in naturally fractured reservoirs. Naturally fractured reservoir characterization digital. Fractured reservoirs using conventional well logs liliana p. On the other hand, they represent some of the largest, most productive reservoirs on earth. The behavior of naturally fractured reservoirs onepetro. In order to predict productivity of multiplefractured horizontal well in fractured reservoir, flow models of reservoir and hydraulic fractures based on the volumetric source idealization are developed. Prediction of naturally fractured reservoir performance. The challenge of estimating recovery from naturally. Naturally fractured reservoirs are elusive systems to characterize and difficult to engineer and predict. Naturally fractured reservoirs fluid flow in petroleum. Pressure response in a naturally fractured reservoir showing ideal dual porosity behavior. Geological analysis of naturally fractured reservoirs. Geologic and engineering aspects of naturally fractured.
Pdf article recovery factors and reserves in naturally. Since all well logs are affected in one way or another by the presence of. Pdf the nature of naturally fractured reservoirs researchgate. 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. Reservoir characterization for naturally fractured reservoirs. 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. Introduction the development of reservoir modeling and reservoir characterization for naturally fractured reservoirs nfrs has lagged behind simpler matrix flow dominated rock. The models are solved by utilizing laplace transformation and orthogonal transformation, and flow rate of the well is calculated by coupling the two models. This webpage version is the ed intellectual property of the author. Recognizing naturally fractured reservoirs petrowiki. 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. The behavior of naturally fractured reservoirs including. The same conclusion was reached earlier by odeh 1965 who studied several fractured reservoirs. They analyzed the e ects of the storativity ratio and interporosity.
Carbonate naturally fractured reservoir is a multiporous system that contain microfractures, fractures, vugs, macrovugs, matrix, type of fractures network. Naturally fractured reservoirs shape factor shahab gerami, fall 2010 1. Pdf characterization of naturally fractured reservoirs gustavo. Geologic analysis of naturally fractured reservoirs. Naturally fractured reservoirs have been classified according to the relative contribution of the matrix and fractures to the total fluid production. The most difficult problem after finding basement rock reservoirs is to evaluate. 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. Petroleum society of cim well might be producing extremely well. This paper describes how integrated reservoir studies including. Naturally fractured reservoirs in the ukcs tim wynn agr tracs 20 may 2018 1. Investigation of recovery mechanisms in fractured reservoirs.
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