Download or read book Physical Optimization of Acid Fracturing with Unified Fracture Design written by Arjun Ravikumar and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Optimization of Multistage Hydraulic Fracturing Treatment for Maximization of the Tight Gas Productivity written by Mengting Li and published by Cuvillier Verlag. This book was released on 2018-12-17 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracturing is essential technology for the development of unconventional resources such as tight gas. So far, there are no numerical tools which can optimize the whole process from geological modeling, hydraulic fracturing until production simulation with the same 3D model with consideration of the thermo-hydro-mechanical coupling. In this dissertation, a workflow and a numerical tool chain were developed for design and optimization of multistage hydraulic fracturing in horizontal well regarding a maximum productivity of the tight gas wellbore. After the verification a full 3D reservoir model is generated based on a real tight gas field in the North German Basin. Through analysis of simulation results, a new calculation formula of FCD was proposed, which takes the proppant position and concentration into account and can predict the gas production rate more accurately. However, not only FCD but also proppant distribution and hydraulic connection of stimulated fractures to the well, geological structure and the interaction between fractures are determinant for the gas production volume. Through analysis the numerical results of sensitivity analysis and optimization variations, there is no unique criterion to determine the optimal number and spacing of the fractures, it should be analyzed firstly in detail to the actual situation and decided then from case to case.

Download or read book Unified Fracture Design written by Michael J. Economides and published by . This book was released on 2002 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanics of Hydraulic Fracturing written by Ching H. Yew and published by Gulf Professional Publishing. This book was released on 2014-09-25 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Revised to include current components considered for today's unconventional and multi-fracture grids, Mechanics of Hydraulic Fracturing, Second Edition explains one of the most important features for fracture design — the ability to predict the geometry and characteristics of the hydraulically induced fracture. With two-thirds of the world's oil and natural gas reserves committed to unconventional resources, hydraulic fracturing is the best proven well stimulation method to extract these resources from their more remote and complex reservoirs. However, few hydraulic fracture models can properly simulate more complex fractures. Engineers and well designers must understand the underlying mechanics of how fractures are modeled in order to correctly predict and forecast a more advanced fracture network. Updated to accommodate today's fracturing jobs, Mechanics of Hydraulic Fracturing, Second Edition enables the engineer to: - Understand complex fracture networks to maximize completion strategies - Recognize and compute stress shadow, which can drastically affect fracture network patterns - Optimize completions by properly modeling and more accurately predicting for today's hydraulic fracturing completions - Discusses the underlying mechanics of creating a fracture from the wellbore - Enhanced to include newer modeling components such as stress shadow and interaction of hydraulic fracture with a natural fracture, which aids in more complex fracture networks - Updated experimental studies that apply to today's unconventional fracturing cases

Download or read book Hydraulic Fracture Optimization with a Pseudo 3D Model in Multi layered Lithology written by Mei Yang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Essentials of Hydraulic Fracturing written by Ralph W. Veatch and published by Pennwell Books. This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracturing was first developed in the United States during the 1940s and has since spread internationally. A proven technology that is reaching deeper and tighter formations, hydraulic fracturing now delivers hydrocarbons from fields previously considered economically unviable. Essentials of Hydraulic Fracturing focuses on consolidating the fundamental basics of fracturing technology with advances in extended horizontal wellbores and fracturing applications. It provides the essentials required to understand fracturing behavior and offers advice for applying that knowledge to fracturing treatment design and application. Essentials of Hydraulic Fracturingis a long-awaited text for petroleum engineering students, industry-wide hydraulic fracturing training courses or seminars, and practicing fracturing treatment engineers. Features include: Understanding of fracture propagation geometry and fracture conductivity and how it affects treatment results A focus on safety and environmental prudence Economic optimization of fracturing treatments Fracturing fluid system and propping agent performance Important considerations in designing the fracture treatment for both vertical and horizontal wellbores Algorithms and examples pertinent to treatment design and analysis Pre- and post-fracturing approaches and diagnostics for evaluating treatment performance Hydraulic fracturing model construction and applicability Comparative design examples Construction of spreadsheet calculations key to treatment designs

Download or read book Optimization of Vertical Acid Fractures in Steady State Flow written by Stephen David Sevougian and published by . This book was released on 1986 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical and Economic Optimization of Hydraulic Fracturing written by Matteo Marongiu Porcu and published by . This book was released on 2007 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Science and Applied Technology ESAT 2016 written by Zhigang Fang and published by CRC Press. This book was released on 2016-10-14 with total page 1125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 2016 International Conference on Energy Science and Applied Technology (ESAT 2016) held on June 25-26 in Wuhan, China aimed to provide a platform for researchers, engineers, and academicians, as well as industrial professionals, to present their research results and development activities in energy science and engineering and its applied technology. The themes presented in Energy Science and Applied Technology ESAT 2016 are: Technologies in Geology, Mining, Oil and Gas; Renewable Energy, Bio-Energy and Cell Technologies; Energy Transfer and Conversion, Materials and Chemical Technologies; Environmental Engineering and Sustainable Development; Electrical and Electronic Technology, Power System Engineering; Mechanical, Manufacturing, Process Engineering; Control and Automation; Communications and Applied Information Technologies; Applied and Computational Mathematics; Methods and Algorithms Optimization; Network Technology and Application; System Test, Diagnosis, Detection and Monitoring; Recognition, Video and Image Processing.

Download or read book Evaluation of Acid Fracturing Based on the acid Fracture Number Concept written by Abdulwahab Alghamdi and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Acid fracturing is one of the preferred methods to stimulate wells in carbonate reservoirs. It consists of injecting an acid solution at high enough pressure to break down the formation and to propagate a two-wing crack away from the wellbore. The acid reacts with the carbonate formation and this causes the etching of the fracture surfaces. After the treatment, the created etched surfaces do not close perfectly and thatl eaves behind a highly conductive path for the hydrocarbons to be produced. We distinguish the issue of treatment sizing (that is the determination of the volume of acid to be injected) and the issue of creating optimum fracture dimensions given the size of the treatment. This is reasonable because the final cost of a treatment is determined mainly by the volume of acid injected and our goal should be to achieve the best performance of the treated well. The well performance depends on the created fracture dimensions and fracture conductivity and might change with time due to various reasons. This research evaluates two field cases from Saudi Aramco where acid fracturing treatment has been used to stimulate a carbonate formation. I investigated the following issues: a) how effective was the treatment to restoring the initial productivity, b) how did the productivity of the well change with time; c) what are the possible reasons for the change in performance, d) what are our options to improve acid fracture design in the future?Based on our research work both near-well liquid drop-out and fracture-conductivitydeterioration can impact the production in different proportion. Moreover, the fracturing model tends to overestimate the fracture conductivity in some cases as shown in SA-2. Also, the "Acid fracture Number" concept proves to be an effective way to evaluate the acid fracturing treatment. Several recommendations were made based on this research work as described in the last part of my thesis.

Download or read book Evaluation of Acid Fracturing Using the Method of Distributed Volumetric Sources written by Jaehun Lee and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Design and Appraisal of Hydraulic Fractures written by Jack R. Jones and published by . This book was released on 2009 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a basic yet comprehensive introduction to the completion and reservoir engineering aspects of hydraulic fracture stimulation.

Download or read book Incorporating Rigorous Height Determination Into Unified Fracture Design written by Termpan Pitakbunkate and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book The Role of Acidizing in Proppant Fracturing in Carbonate Reservoirs written by Jurairat Densirimongkol and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, optimizing well stimulation techniques to obtain maximum return of investment is still a challenge. Hydraulic fracturing is a typical application to improve ultimate recovery from oil and gas reservoirs. Proppant fracturing has become one of the most widely considered alternatives for application in carbonate reservoirs. Especially in areas that have high closure stress, the non-smoothly etched surface created by acid fracturing may not remain open upon closing, resulting in decrease in fracture conductivity and unsuccessful stimulation treatment. In early years, because of the increase in the success of proppant fracturing, proppant partial monolayer has been put forward as a method that helps generate the maximum fracture conductivity from proppant fracturing treatment. However, this method was not widely successful because of proppant crushing and proppant embedment problems that result in losing conductivity. The ability to transport propping agents in available fracturing fluid was also poor and resulted in difficulties and failures to obtain proppant partial monolayer placement. For carbonate formations, acid fracturing is another effective stimulation method. Simpler operation and lower cost made the technique attractive in the field with plenty of successful experiences. The heterogeneity feature of carbonate formation brings a challenge to create sufficient conductivity. In cases of high closure formation, fracture conductivity is hard to sustain. This factor limited the applications of acid fracturing sometimes. In this study, laboratory tests were carried out using low concentrations of ultralightweight proppant to obtain partial monolayer proppant. Because of low specific gravity property of this proppant, it was claimed to help improve proppant transport inside the fracture. In this experimental study, the partial monolayer technique was examined with particular emphasis upon the impact of acid in possibly improving fracture conductivity of carbonate rocks. The technique is referred as "closed fracture acidizing". After obtaining a partial monolayer distribution on the fracture face, gelled acid was injected through the fracture face. Fracture conductivity before and after acid injection were evaluated. Experimental results showed clearly that acid injection does not enhance fracture conductivity of partial monolayer proppant fracturing. The more the volume of acid injection, the more rapidly fracture conductivity declines.

Download or read book Three dimensional Modeling of Acid Transport and Etching in a Fracture written by Cassandra Vonne Oeth and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Hydraulic Fracturing Optimization written by Andreas Michael and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracturing is a reservoir stimulation technique used in the petroleum industry since 1947. High pressure fluid composed mainly of water generates cracks near the wellbore improving the surrounding permeability and enhancing the flow of oil and gas to the surface. Advances in hydraulic fracturing coupled with developments in horizontal drilling, have unlocked vast quantities of unconventional resources, previously believed impossible to be produced. Fracture creation induces perturbations in the nearby in-situ stress regime suppressing the initiation and propagation of other fractures. Neighboring fractures are affected by this stress shadow effect, causing them to grow dissimilarly and they receive unequal portions of the injected fluid. Numerical simulation models have shown that non-uniform perforation cluster distributions with interior fractures closer to the exterior ones can balance out these stress shadow effects, promoting more homogeneous multiple fracture growth compared to uniform perforation cluster distributions. In this work, laboratory-scale tests on three perforation configurations are performed on transparent specimens using distinctly colored fracturing fluids such that fracture growth can be observed. A normal faulting stress regime is replicated with the introduction of an overburden load in a confined space. The results have shown that uniform perforation spacing configurations yields higher degree of fracture growth homogeneity, as maximum spacing minimizes stress shadow effects, compared to moving the middle perforation closer to the toe, or heel of the horizontal well. The experiments also showed a proclivity to form one dominant fracture. Time delay, neglected in most theoretical modelling studies, between fracture initiations is found to be a key parameter and is believed to be one of the major factors promoting this dominant fracture tendency along with wellbore pressure gradients. Moreover, in several cases, the injected bypassed perforation(s) to generate fracture(s) downstream. Finally, the compressibility of the fracturing fluid triggered somewhat unexpected transient pressure behavior. The understanding of the stress shadow effects and what influences them could lead to optimization of hydraulic fracturing treatment design in terms of productivity and cost. Therefore, achieving more homogeneous multiple fracture growth patterns can be pivotal on the economic feasibility of several stimulation treatments.

Download or read book Petroleum Abstracts Literature and Patents written by and published by . This book was released on 1990 with total page 1416 pages. Available in PDF, EPUB and Kindle. Book excerpt: