Author: Jianye Mou Publisher: ISBN: Category : Languages : en Pages :
Book Description
Success of acid fracturing depends on uneven etching along the fracture surfaces caused by heterogeneities such as variations in local mineralogy and variations in leakoff behavior. The heterogeneities tend to create channeling characteristics, which provide lasting conductivity after fracture closure, and occur on a scale that is neither used in laboratory measurements of acid fracture conductivity, which use core samples that are too small to observe such a feature, nor in typical acid fracture simulations in which the grid block size is much larger than the scale of local heterogeneities. Acid fracture conductivity depends on fracture surface etching patterns. Existing acid fracture conductivity correlations are for random asperity distributions and do not consider the contribution of channels to the conductivity. An acid fracture conductivity correlation needs the average fracture width at zero closure stress. Existing correlations calculate average fracture width using dissolved rock equivalent width without considering the effect of reservoir characteristics. The purpose of this work is to develop an intermediate-scale acid fracture model with grid size small enough and the whole dimension big enough to capture local and macro heterogeneity effects and channeling characteristics in acid fracturing. The model predicts pressure field, flow field, acid concentration profiles, and fracture surface profiles as a function of acid contact time. By extensive numerical experiments with the model, we develop correlations of fracture conductivity and average fracture width at zero closure stress as a function of statistical parameters of permeability and mineralogy distributions. With the model, we analyzed the relationships among fracture surface etching patterns, conductivities, and the distributions of permeability and mineralogy. From result analysis, we found that a fracture with channels extending from the inlet to the outlet of the fracture has a high conductivity because fluid flow in deep channels needs a very small pressure drop. Such long and highly conductive channels can be created by acids if the formation has heterogeneities in either permeability or mineralogy, or both, with high correlation length in the direction of the fracture, which is the case in laminated formations.
Author: Cassandra Vonne Oeth Publisher: ISBN: Category : Languages : en Pages :
Book Description
Acid fracture stimulation generates higher well production but requires engineering design for treatment optimization. To quantify the cost and benefit of a particular acid fracture treatment an engineer must predict the resulting fracture's conductivity, which is based on the etched width created by the injected acid. Etching occurs along the fracture surface but is based on acid flowing through the fracture, so an evaluation tool should describe three-dimensional physics and chemistry. Current practice is to estimate conductivity utilizing two-dimensional models. Unfortunately, these models necessarily assume how acid is distributed in the fracture and often misrepresent the amount of acid etching upon which the conductivity is based. A fully three-dimensional modeling tool to evaluate and predict acid fracture performance across the wide range of carbonate field properties has been developed. The model simulates acid transport and fracture face dissolution. The acid transport model includes the solution of the three-dimensional velocity and pressure fields, the non-Newtonian characteristics of most acid fracturing fluids, and diffusion of acid toward the fracture surface. The model numerically solves the equations describing the three-dimensional acid transport and reaction within a fracture to yield the etched width created by acid along the fracture. The conductivity is calculated with the simulator derived acid-etched width, using correlations recently developed that reflect the small scale heterogeneity of carbonate rock as it creates etching along the fracture surface. The performance of an acid fracture treatment is quantified with conductivity, which is strongly dependent on the etched width created by the acid. This robust new tool more accurately models the impact of design decisions on the acid-etched width and provides a rational path for treatment optimization. Cases typical of industry practice are presented that demonstrate the model capabilities. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151892
Author: Rencheng Dong Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Matrix acidizing and acid fracturing are two main types of acid stimulation treatments that are extensively employed by industry in carbonate reservoirs to improve permeability and enhance production. Matrix acidizing involves injecting acid to dissolve minerals in order to create long highly conductive channels (wormholes) whereas acid fracturing is used to etch fracture surfaces and create fracture conductivity. Numerical modeling of acid stimulation treatments couples processes of fluid flow, reactive transport, and rock dissolution, which imposes great computational challenges. The purpose of this dissertation is to develop efficient and accurate numerical models for acidizing process and acid fracturing process respectively. In most of matrix acidizing simulations, acid transport is generally solved by a single-point upwinding (SPU) scheme based on finite volume method. Simulation results of wormhole growth may have large numerical errors due to grid orientation effect of SPU scheme. In this work, we apply adaptive enriched Galerkin (EG) methods for solving coupled flow and reactive transport equations of acidizing model. EG is constructed by enriching the standard continuous Galerkin (CG) finite element method with piecewise constant functions. Since EG is a higher-order method compared with standard finite volume method, EG reduces non-physical numerical errors caused by grid orientation effect. Wormhole growth usually exhibits fingering patterns, which requires very fine mesh to resolve. Instead of global mesh refinement, we apply adaptive mesh refinement technique to dynamically refine the mesh in the vicinity of wormhole interfaces and coarsen the mesh after dissolution fronts pass. The simulation runtime using adaptive mesh is only about 30% of the runtime using globally refined mesh in our numerical examples. The key to success in acid fracturing treatments is to achieve non-uniform acid etching on fracture surfaces. Carbonate reservoir heterogeneity such as heterogeneous mineral distribution can lead to non-uniform acid etching. In addition, the non-uniform acid etching can be enhanced by the viscous fingering mechanism. By injecting a low-viscosity acid into a high-viscosity polymer pad fluid, acid tends to form viscous fingers and etch fracture surfaces non-uniformly. Acid fracturing simulations rarely modeled the effect of acid viscous fingering. In this work, a 3D acid fracturing model is developed to simulate acid etching process with acid viscous fingering. Our acid fracturing model considers fluid flow inside the fracture, acid and polymer transport, and change of fracture geometry due to mineral dissolution. A numerical simulator is developed to solve the acid fracturing model and compute the rough acid fracture geometry induced by non-uniform acid etching. We investigate the effects of viscous fingering, perforation design, and alternating injection of pad and acid fluids on the acid etching process. Our model is capable of simulating growth of acid-etched channels caused by acid viscous fingering. According to our simulation results, properly increasing the number of perforations can restrain the height of acid-etched channels and help sustain acid fracture conductivity under the reservoir closure stress. Compared with single-stage acid injection, multi-stage alternating injection of pad and acid fluids leads to narrower and longer acid-etched channels, which improves the effectiveness of acid fracturing treatments
Author: Jaehun Lee Publisher: ISBN: Category : Languages : en Pages :
Book Description
Acid fracturing stimulation is one of the preferred methods to improve well productivity in carbonate reservoirs. Acid is injected into the fractured zone after a starter fracture is created in the near wellbore area by viscous fluid (pad). This results in propagation of a two-wing crack away from the perforations with simultaneous dissolution etching of the created surfaces. If the created etched surface is non-uniform, then after the treatment ends and the fracture face closes, a high conductivity path may remain in the formation, connected to the well. The important factors controlling the effectiveness of acid fracturing are the etched-fracture penetration and conductivity. In this research, I use the distributed volumetric sources (DVS) method to calculate gas production from a well stimulated by acid fracturing. The novel concept realized in this research is that, during the production process, the conductivity of the acid created fracture changes. I use the Nierode - Kruk correlation to describe this effect as a function of effective closure stress that in turn is determined from the flowing bottomhole pressure and minimum horizontal stress. By combining the well productivity calculation from the DVS method taking into account varying fracture conductivity with gas material balance, I obtain an improved model of gas production. The model is then used to not only forecast production from acid fractured wells but also to evaluate the known production history of such wells. Based on the concepts discussed above, I have developed a program called "Gas Acid" which is useful to optimize acid fracturing treatments and also suitable to infer created fracture parameters from known production history. The "Gas Acid" program has been validated with data from two Saudi Aramco gas wells. It was found that the production forecast obtained from the "Gas Acid" program matches the actual production history with reasonable accuracy and the remaining discrepancy could be resolved by taking into account refinement of the material balance. The refinement became necessary, because the "Gas Acid" program was developed for dry gas but the reservoir fluids in the field examples were classified as retrograde gas and wet gas. When accounting for the additional mass of gas "hidden" in the produced condensate, the match of forecast and actual data was improved considerably.
Author: Harald Ibach Publisher: Springer Science & Business Media ISBN: 3540347100 Category : Science Languages : en Pages : 653
Book Description
This graduate-level textbook covers the major developments in surface sciences of recent decades, from experimental tricks and basic techniques to the latest experimental methods and theoretical understanding. It is unique in its attempt to treat the physics of surfaces, thin films and interfaces, surface chemistry, thermodynamics, statistical physics and the physics of the solid/electrolyte interface in an integral manner, rather than in separate compartments. It is designed as a handbook for the researcher as well as a study-text for graduate students. Written explanations are supported by 350 graphs and illustrations.
Author: M.L. Plumer Publisher: Springer Science & Business Media ISBN: 364256657X Category : Science Languages : en Pages : 364
Book Description
Application-oriented book on magnetic recording, focussing on the underlying physical mechanisms that play crucial roles in medium and transducer development for high areal density disk drives.
Author: Grant Heiken Publisher: CUP Archive ISBN: 9780521334440 Category : Science Languages : en Pages : 796
Book Description
The only work to date to collect data gathered during the American and Soviet missions in an accessible and complete reference of current scientific and technical information about the Moon.
Author: Zinoviy Nazarchuk Publisher: Springer ISBN: 3319493507 Category : Technology & Engineering Languages : en Pages : 294
Book Description
This monograph analyses in detail the physical aspects of the elastic waves radiation during deformation or fracture of materials. It presents the methodological bases for the practical use of acoustic emission device, and describes the results of theoretical and experimental researches of evaluation of the crack growth resistance of materials, selection of the useful AE signals. The efficiency of this methodology is shown through the diagnostics of various-purpose industrial objects. The authors obtain results of experimental researches with the help of the new methods and facilities.
Author: Gary S. May Publisher: John Wiley & Sons ISBN: 0471790273 Category : Technology & Engineering Languages : en Pages : 428
Book Description
A practical guide to semiconductor manufacturing from processcontrol to yield modeling and experimental design Fundamentals of Semiconductor Manufacturing and Process Controlcovers all issues involved in manufacturing microelectronic devicesand circuits, including fabrication sequences, process control,experimental design, process modeling, yield modeling, and CIM/CAMsystems. Readers are introduced to both the theory and practice ofall basic manufacturing concepts. Following an overview of manufacturing and technology, the textexplores process monitoring methods, including those that focus onproduct wafers and those that focus on the equipment used toproduce wafers. Next, the text sets forth some fundamentals ofstatistics and yield modeling, which set the foundation for adetailed discussion of how statistical process control is used toanalyze quality and improve yields. The discussion of statistical experimental design offers readers apowerful approach for systematically varying controllable processconditions and determining their impact on output parameters thatmeasure quality. The authors introduce process modeling concepts,including several advanced process control topics such asrun-by-run, supervisory control, and process and equipmentdiagnosis. Critical coverage includes the following: * Combines process control and semiconductor manufacturing * Unique treatment of system and software technology and managementof overall manufacturing systems * Chapters include case studies, sample problems, and suggestedexercises * Instructor support includes electronic copies of the figures andan instructor's manual Graduate-level students and industrial practitioners will benefitfrom the detailed exami?nation of how electronic materials andsupplies are converted into finished integrated circuits andelectronic products in a high-volume manufacturingenvironment. An Instructor's Manual presenting detailed solutions to all theproblems in the book is available from the Wiley editorialdepartment. An Instructor Support FTP site is also available.
Author: Jianye Mou
Author: Cassandra Vonne Oeth
Author: Rencheng Dong
Author: Jaehun Lee
Author: Michael J. Economides
Author: Harald Ibach
Author: M.L. Plumer
Author: Grant Heiken
Author: Zinoviy Nazarchuk
Author: Gary S. May