Unified Fracture Design
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Unified Fracture Design
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Author : Michael J. Economides
language : en
Publisher:
Release Date : 2002
Unified Fracture Design written by Michael J. Economides and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Technology & Engineering categories.
Incorporating Rigorous Height Determination Into Unified Fracture Design
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Author : Termpan Pitakbunkate
language : en
Publisher:
Release Date : 2010
Incorporating Rigorous Height Determination Into Unified Fracture Design written by Termpan Pitakbunkate and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Hydraulic fracturing plays an important role in increasing production rate in tight reservoirs. The performance of the reservoir after fracturing can be observed from the productivity index. This parameter is dependent on the fracture geometry; height, length and width. Unified fracture design (UFD) offers a method to determine the fracture dimensions providing the maximum productivity index for a specific proppant amount. Then, in order to achieve the maximum productivity index, the treatment schedules including the amount of liquid and proppant used for each stage must be determined according to the fracture dimensions obtained from the UFD. The proppant number is necessary for determining the fracture geometry using the UFD. This number is used to find the maximum productivity index for a given proppant amount. Then, the dimensionless fracture conductivity index corresponding to the maximum productivity index can be computed. The penetration ration, the fracture length, and the propped fracture width can be computed from the dimensionless fracture conductivity. However, calculating the proppant number used in UFD requires the fracture height as an input. The most convenient way to estimate fracture height to input to the UFD is to assume that the fracture height is restricted by stress contrast between the pay zone and over and under-lying layers. In other words, the fracture height is assumed to be constant, independent of net pressure and equal to the thickness of the layer which has the least minimum principal stress. However, in reality, the fracture may grow out from the target formation and the height of fracture is dependent on the net pressure during the treatment. Therefore, it is necessary to couple determination of the fracture height with determination of the other fracture parameters. In this research, equilibrium height theory is applied to rigorously determine the height of fracture. Solving the problem iteratively, it is possible to incorporate the rigorous fracture height determination into the unified fracture design.
Physical Optimization Of Acid Fracturing With Unified Fracture Design
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Author : Arjun Ravikumar
language : en
Publisher:
Release Date : 2014
Physical Optimization Of Acid Fracturing With Unified Fracture Design written by Arjun Ravikumar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Petroleum engineering categories.
Acid fracturing is a reservoir stimulation technique where a fracture is created by injection of acid into the reservoir instead of conventional proppant slurry. The acid causes differential etching on the fracture walls, creating asperities. These asperities hold up the fracture wall, thus contributing to fracture conductivity. Acid fracturing is used mainly to stimulate carbonate rock. This technique has certain advantages over conventional fracturing. There is no proppant used, therefore the risk of screenout is nullified. There are also logistic reasons such as transport of proppant, which might make acid fracturing a viable choice. Theoretically, acid fractures have infinite conductivity in these conduits. This is not always true in practice. In this work, a physical optimization of acid fracturing is performed by utilizing the Unified Fracture Design methodology (UFD, hereforth). Parametric studies are performed to study the dependency of productivity on various factors.
Methodologies And New User Interfaces To Optimize Hydraulic Fracturing Design And Evaluate Fracturing Performance For Gas Wells
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Author : Wenxin Wang
language : en
Publisher:
Release Date : 2006
Methodologies And New User Interfaces To Optimize Hydraulic Fracturing Design And Evaluate Fracturing Performance For Gas Wells written by Wenxin Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
This thesis presents and develops efficient and effective methodologies for optimal hydraulic fracture design and fracture performance evaluation. These methods incorporate algorithms that simultaneously optimize all of the treatment parameters while accounting for required constraints. Damage effects, such as closure stress, gel damage and non-Darcy flow, are also considered in the optimal design and evaluation algorithms. Two user-friendly program modules, which are active server page (ASP) based, were developed to implement the utility of the methodologies. Case analysis was executed to demonstrate the workflow of the two modules. Finally, to validate the results from the two modules, results were compared to those from a 3D simulation program. The main contributions of this work are: An optimal fracture design methodology called unified fracture design (UFD)is presented and damage effects are considered in the optimal design calculation. As a by-product of UFD, a fracture evaluation methodology is proposed to conduct well stimulation performance evaluation. The approach is based on calculating and comparing the actual dimensionless productivity index of fractured wells with the benchmark which has been developed for optimized production. To implement the fracture design and evaluation methods, two web ASP based user interfaces were developed; one is called Frac Design (Screening), and the other is Frac Evaluation. Both modules are built to hold the following features. Friendly web ASP based user interface Minimum user inputo Proppant type and mesh size selection- Damage effects consideration options- Convenient on-line help.
A Unified Technology Plan For Fatigue And Fracture Design
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Author : Herbert F. Hardrath
language : en
Publisher:
Release Date : 1973
A Unified Technology Plan For Fatigue And Fracture Design written by Herbert F. Hardrath and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with Airframes categories.
Hydraulic Fracture Optimization With A Pseudo 3d Model In Multi Layered Lithology
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Author : Mei Yang
language : en
Publisher:
Release Date : 2011
Hydraulic Fracture Optimization With A Pseudo 3d Model In Multi Layered Lithology written by Mei Yang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Hydraulic Fracturing is a technique to accelerate production and enhance ultimate recovery of oil and gas while fracture geometry is an important aspect in hydraulic fracturing design and optimization. Systematic design procedures are available based on the so-called two-dimensional models (2D) focus on the optimization of fracture length and width, assuming one can estimate a value for fracture height, while so-called pseudo three dimensional (p-3D) models suitable for multi-layered reservoirs aim to maximize well production by optimizing fracture geometry, including fracture height, half-length and width at the end of the stimulation treatment. The proposed p-3D approach to design integrates four parts: 1) containment layers discretization to allow for a range of plausible fracture heights, 2) the Unified Fracture Design (UFD) model to calculate the fracture half-length and width, 3) the PKN or KGD models to predict hydraulic fracture geometry and the associated net pressure and other treatment parameters, and, finally, 4) Linear Elastic Fracture Mechanics (LEFM) to calculate fracture height. The aim is to find convergence of fracture height and net pressure. Net pressure distribution plays an important role when the fracture is propagating in the reservoir. In multi-layered reservoirs, the net pressure of each layer varies as a result of different rock properties. This study considers the contributions of all layers to the stress intensity factor at the fracture tips to find the final equilibrium height defined by the condition where the fracture toughness equals the calculated stress intensity factor based on LEFM. Other than maximizing production, another obvious application of this research is to prevent the fracture from propagating into unintended layers (i.e. gas cap and/or aquifer). Therefore, this study can aid fracture design by pointing out: (1) Treating pressure needed to optimize fracture geometry, (2) The containment top and bottom layers of a multi-layered reservoir, (3) The upwards and downwards growth of the fracture tip from the crack center.
Non Darcy Flow And Multi Phase Flow
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Author : Nasraldin Alarbi
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2011-12
Non Darcy Flow And Multi Phase Flow written by Nasraldin Alarbi and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-12 with categories.
Hydraulic fracturing has recently been the completion of choice for most tight gas formations. It has proven successful to produce these formations in a commercial manner. However, some considerations have to be taken into account when designing a fracture treatment. These considerations include, but not limited to, non-Darcy flow and multiphase flow effects inside the fracture. These effects reduce the fracture conductivity significantly. Failing to account for that results in overestimating the deliverability of the wells and, consequently, to designing a fracture treatment that is not optimum. In this book a thorough investigation of non-Darcy flow and multi-phase flow effects on the productivity of hydraulically fractured gas wells is conducted and an optimum fracture design is proposed for a tight gas formation in south Texas using the Unified Fracture Design (UFD) Technique to compensate for the mentioned effects by calculating the effective fracture permeability in an iterative way. A comparison between the UFD and the most well known 3D fracture simulators is also carried out to point out the differences as far as the methodology and design considerations.
Petroleum Production Stimulation
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Author : Mei Yang
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2011-12
Petroleum Production Stimulation written by Mei Yang and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-12 with Hydraulic engineering categories.
A multi-layered p-3D approach to design is proposed integrating Unified Fracture Design (UFD), fracture propagation models and Linear Elastic Fracture Mechanics (LEFM) relationship to generate optimized fracture geometry, including fracture height, width and half-length to achieve the maximized production. Containment layers are discretized to allow for plausible fracture heights when seeking convergence of fracture height and net pressure. Other than the physical fracture geometry optimization, thus maximizing production, another obvious application of this research is to prevent the fracture from propagating into the unintended layers (i.e. gas cap and aquifer). Therefore, this study can guide fracture design job by pointing out: (1) what treating pressure is needed to achieve the optimum fracture geometry; (2) at which containment layers of the multi-layers will the vertical fracture propagation stop, given the above treating pressure; (3) the layer discretization will allow an approximate location of the fracture top and bottom tips which is sufficient for the purposes of this design.
Analysis Of Hydraulic Fracture Propagation In Fractured Reservoirs
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Author : Arash Dahi Taleghani
language : en
Publisher:
Release Date : 2009
Analysis Of Hydraulic Fracture Propagation In Fractured Reservoirs written by Arash Dahi Taleghani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Gas reservoirs categories.
Large volumes of natural gas exist in tight fissured reservoirs. Hydraulic fracturing is one of the main stimulating techniques to enhance recovery from these fractured reservoirs. Although hydraulic fracturing has been used for decades for the stimulation of tight gas reservoirs, a thorough understanding of the interaction between induced hydraulic fractures and natural fractures is still lacking. Recent examples of hydraulic fracture diagnostic data suggest complex, multi-stranded hydraulic fracture geometry is a common occurrence. The interaction between pre-existing natural fractures and the advancing hydraulic fracture is a key condition leading to complex fracture patterns. Large populations of natural fractures that exist in formations such as the Barnett shale are sealed by precipitated cements which could be quartz, calcite, etc. Even though there is no porosity in the sealed fractures, they may still serve as weak paths for fracture initiation and/or for diverting the path of the growing hydraulic fractures. Performing hydraulic fracture design calculations under these complex conditions requires modeling of fracture intersections and tracking fluid fronts in the network of reactivated fissures. In this dissertation, the effect of the cohesiveness of the sealed natural fractures and the intact rock toughness in hydraulic fracturing are studied. Accordingly, the role of the pre-existing fracture geometry is also investigated. The results provide some explanations for significant differences in hydraulic fracturing in naturally fractured reservoirs from non-fractured reservoirs. For the purpose of this research, an extended finite element method (XFEM) code is developed to simulate fracture propagation, initiation and intersection. The motivation behind applying XFEM are the desire to avoid remeshing in each step of the fracture propagation, being able to consider arbitrary varying geometry of natural fractures and the insensitivity of fracture propagation to mesh geometry. New modifications are introduced into XFEM to improve stress intensity factor calculations, including fracture intersection criteria into the model and improving accuracy of the solution in near crack tip regions. The presented coupled fluid flow-fracture mechanics simulations extend available modeling efforts and provide a unified framework for evaluating fracture design parameters and their consequences. Results demonstrate that fracture pattern complexity is strongly controlled by the magnitude of in situ stress anisotropy, the rock toughness, the natural fracture cement strength, and the approach angle of the hydraulic fracture to the natural fracture. Previous studies (mostly based on frictional fault stability analysis) have concentrated on predicting the onset of natural fracture failure. However, the use of fracture mechanics and XFEM makes it possible to evaluate the progression of fracture growth over time as fluid is diverted into the natural fractures. Analysis shows that the growing hydraulic fracture may exert enough tensile and/or shear stresses on cemented natural fractures that they may be opened or slip in advance of hydraulic fracture tip arrival, while under some conditions, natural fractures will be unaffected by the hydraulic fracture. A threshold is defined for the fracture energy of cements where, for cases below this threshold, hydraulic fractures divert into the natural fractures. The value of this threshold is calculated for different fracture set orientations. Finally, detailed pressure profile and aperture distributions at the intersection between fracture segments show the potential for difficulty in proppant transport under complex fracture propagation conditions. Whether a hydraulic fracture crosses or is arrested by a pre-existing natural fracture is controlled by shear strength and potential slippage at the fracture intersections, as well as potential debonding of sealed cracks in the near-tip region of a propagating hydraulic fracture. We introduce a new more general criterion for fracture propagation at the intersections. We present a complex hydraulic fracture pattern propagation model based on the Extended Finite Element Method as a design tool that can be used to optimize treatment parameters under complex propagation conditions.
Investigation Of The Effect Of Non Darcy Flow And Multi Phase Flow On The Productivity Of Hydraulically Fractured Gas Wells
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Author : Nasraldin Abdulslam A. Alarbi
language : en
Publisher:
Release Date : 2011
Investigation Of The Effect Of Non Darcy Flow And Multi Phase Flow On The Productivity Of Hydraulically Fractured Gas Wells written by Nasraldin Abdulslam A. Alarbi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Hydraulic fracturing has recently been the completion of choice for most tight gas bearing formations. It has proven successful to produce these formations in a commercial manner. However, some considerations have to be taken into account to design an optimum stimulation treatment that leads to the maximum possible productivity. These considerations include, but not limited to, non-Darcy flow and multiphase flow effects inside the fracture. These effects reduce the fracture conductivity significantly. Failing to account for that results in overestimating the deliverability of the well and, consequently, to designing a fracture treatment that is not optimum. In this work a thorough investigation of non-Darcy flow and multi-phase flow effects on the productivity of hydraulically fractured wells is conducted and an optimum fracture design is proposed for a tight gas formation in south Texas using the Unified Fracture Design (UFD) Technique to compensate for the mentioned effects by calculating the effective fracture permeability in an iterative way. Incorporating non-Darcy effects results in an optimum fracture that is shorter and wider than the fracture when only Darcy calculations are considered. That leads to a loss of production of 5, 18% due to dry and multiphase non-Darcy flow effects respectively. A comparison between the UFD and 3D simulators is also done to point out the differences in terms of methodology and results. Since UFD incorporated the maximum dimensionless productivity index in the fracture dimensions design, unlike 3D simulators, it can be concluded that using UFD to design the fracture treatment and then use the most important fracture parameters outputs (half length and CfDopt) as inputs in the simulators is a recommended approach.