The Performance Of Fractured Horizontal Well In Tight Gas Reservoir
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The Performance Of Fractured Horizontal Well In Tight Gas Reservoir
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Author : Jiajing Lin
language : en
Publisher:
Release Date : 2012
The Performance Of Fractured Horizontal Well In Tight Gas Reservoir written by Jiajing Lin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Horizontal wells have been used to increase reservoir recovery, especially in unconventional reservoirs, and hydraulic fracturing has been applied to further extend the contact with the reservoir to increase the efficiency of development. In the past, many models, analytical or numerical, were developed to describe the flow behavior in horizontal wells with fractures. Source solution is one of the analytical/semi-analytical approaches. To solve fractured well problems, source methods were advanced from point sources to volumetric source, and pressure change inside fractures was considered in the volumetric source method. This study aims at developing a method that can predict horizontal well performance and the model can also be applied to horizontal wells with multiple fractures in complex natural fracture networks. The method solves the problem by superposing a series of slab sources under transient or pseudosteady-state flow conditions. The principle of the method comprises the calculation of semi-analytical response of a rectilinear reservoir with closed outer boundaries. A statistically assigned fracture network is used in the study to represent natural fractures based on the spacing between fractures and fracture geometry. The multiple dominating hydraulic fractures are then added to the natural fracture system to build the physical model of the problem. Each of the hydraulic fractures is connected to the horizontal wellbore, and the natural fractures are connected to the hydraulic fractures through the network description. Each fracture, natural or hydraulically induced, is treated as a series of slab sources. The analytical solution of superposed slab sources provides the base of the approach, and the overall flow from each fracture and the effect between the fractures are modeled by applying superposition principle to all of the fractures. It is assumed that hydraulic fractures are the main fractures that connect with the wellbore and the natural fractures are branching fractures which only connect with the main fractures. The fluid inside of the branch fractures flows into the main fractures, and the fluid of the main fracture from both the reservoir and the branch fractures flows to the wellbore. Predicting well performance in a complex fracture network system is extremely challenged. The statistical nature of natural fracture networks changes the flow characteristic from that of a single linear fracture. Simply using the single fracture model for individual fracture, and then adding the flow from each fracture for the network could introduce significant error. This study provides a semi-analytical approach to estimate well performance in a complex fracture network system.
Modeling Performance Of Horizontal Wells With Multiple Fractures In Tight Gas Reservoirs
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Author : Guangwei Dong
language : en
Publisher:
Release Date : 2011
Modeling Performance Of Horizontal Wells With Multiple Fractures In Tight Gas Reservoirs written by Guangwei Dong 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.
Multiple transverse fracturing along a horizontal well is a relatively new technology that is designed to increase well productivity by increasing the contact between the reservoir and the wellbore. For multiple transverse fractures, the performance of the well system is determined by three aspects: the inflow from the reservoir to the fracture, the flow from the fracture to the wellbore, and the inflow from the reservoir to the horizontal wellbore. These three aspects influence each other and combined, influence the wellbore outflow. In this study, we develop a model to effectively formulate the inter-relationships of a multi-fracture system. This model includes a reservoir model and a wellbore model. The reservoir model is established to calculate both independent and inter-fracture productivity index to quantify the contribution from all fractures on pressure drop of each fracture, by using the source functions to solve the single-phase gas reservoir flow model. The wellbore model is used to calculate the pressure distribution along the wellbore and the relationship of pressure between neighboring fractures, based on the basic pressure drop model derived from the mechanical energy balance. A set of equations with exactly the same number of fractures will be formed to model the system by integrating the two models. Because the equations are nonlinear, iteration method is used to solve them. With our integrated reservoir and wellbore model, we conduct a field study to find the best strategy to develop the field by hydraulic fracturing. The influence of reservoir size, horizontal and vertical permeability, well placement, and fracture orientation, type (longitudinal and transverse), number and distribution are completely examined in this study. For any specific field, a rigorous step-by-step procedure is proposed to optimize the field.
The Effect Of Well Trajectory On Production Performance Of Tight Gas Wells
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Author : Mohammad Aldousari
language : en
Publisher:
Release Date : 2012
The Effect Of Well Trajectory On Production Performance Of Tight Gas Wells written by Mohammad Aldousari and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Horizontal wells are a very important element in oil and gas industry due to their distinguished advantages. Horizontal wells are not technically horizontal. This is because of the structural nature of reservoir formations and drilling procedures. In response to the reservoir rock's strength, the horizontal well deviates upward and downward while being drilled forming an undulating path instead of a horizontal. In this study, horizontal wells with an undulating trajectory within a gas reservoir have been studied. The aim of this research is to investigate the effect of the trajectory angle on pressure drop in horizontal wells. In addition, the contribution of water flow to pressure drop is a part of this research. Generally, water comes from different sources like an aquifer or a water flood job. In low permeability horizontal wells, hydraulic fracturing introduces water to gas wells. Water distribution is an important issue in gas wells production. In order to achieve the goal of this study, a model has been developed to simulate different situations for a horizontal well with an undulating trajectory in gas reservoirs. This study is a step forward to understand well performance in low permeability gas reservoirs.
Optimization Of Fractured Well Performance Of Horizontal Gas Wells
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Author : Fellipe Vieira Magalhães
language : en
Publisher:
Release Date : 2010
Optimization Of Fractured Well Performance Of Horizontal Gas Wells written by Fellipe Vieira Magalhães 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.
In low-permeability gas reservoirs, horizontal wells have been used to increase the reservoir contact area, and hydraulic fracturing has been further extending the contact between wellbores and reservoirs. This thesis presents an approach to evaluate horizontal well performance for fractured or unfractured gas wells and a sensitivity study of gas well performance in a low permeability formation. A newly developed Distributed Volumetric Sources (DVS) method was used to calculate dimensionless productivity index for a defined source in a box-shaped domain. The unique features of the DVS method are that it can be applied to transient flow and pseudo-steady state flow with a smooth transition between the boundary conditions. In this study, I conducted well performance studies by applying the DVS method to typical tight sandstone gas wells in the US basins. The objective is to determine the best practice to produce horizontal gas wells. For fractured wells, well performance of a single fracture and multiple fractures are compared, and the effect of the number of fractures on productivity of the well is presented based on the well productivity. The results from this study show that every basin has a unique ideal set of fracture number and fracture length. Permeability plays an important role on dictating the location and the dimension of the fractures. This study indicated that in order to achieve optimum production, the lower the permeability of the formation, the higher the number of fractures.
Numerical Modeling Of Fractured Shale Gas And Tight Gas Reservoirs Using Unstructured Grids
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Author : Olufemi Morounfopefoluwa Olorode
language : en
Publisher:
Release Date : 2012
Numerical Modeling Of Fractured Shale Gas And Tight Gas Reservoirs Using Unstructured Grids written by Olufemi Morounfopefoluwa Olorode and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Various models featuring horizontal wells with multiple induced fractures have been proposed to characterize flow behavior over time in tight gas and shale gas systems. Currently, there is little consensus regarding the effects of non-ideal fracture geometries and coupled primary-secondary fracture interactions on reservoir performance in these unconventional gas reservoirs. This thesis provides a grid construction tool to generate high-resolution unstructured meshes using Voronoi grids, which provides the flexibility required to accurately represent complex geologic domains and fractures in three dimensions. Using these Voronoi grids, the interaction between propped hydraulic fractures and secondary "stress-release" fractures were evaluated. Additionally, various primary fracture configurations were examined, where the fractures may be non-planar or non-orthogonal. For this study, a numerical model was developed to assess the potential performance of tight gas and shale gas reservoirs. These simulations utilized up to a half-million grid-blocks and consider a period of up to 3,000 years in some cases. The aim is to provide very high-definition reference numerical solutions that will exhibit virtually all flow regimes we can expect in these unconventional gas reservoirs. The simulation results are analyzed to identify production signatures and flow regimes using diagnostic plots, and these interpretations are confirmed using pressure maps where useful. The coupled primary-secondary fracture systems with the largest fracture surface areas are shown to give the highest production in the traditional "linear flow" regime (which occurs for very high conductivity vertical fracture cases). The non-ideal hydraulic fracture geometries are shown to yield progressively lower production as the angularity of these fractures increases. Hence, to design optimum fracture completions, we should endeavor to keep the fractures as orthogonal to the horizontal well as possible. This work expands the current understanding of flow behavior in fractured tight-gas and shale-gas systems and may be used to optimize fracture and completion design, to validate analytical models and to facilitate more accurate reserves estimation.
Performance Analysis And Optimization Of Well Production In Unconventional Resource Plays
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Author : Baljit Singh Sehbi
language : en
Publisher:
Release Date : 2013
Performance Analysis And Optimization Of Well Production In Unconventional Resource Plays written by Baljit Singh Sehbi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
The Unconventional Resource Plays consisting of the lowest tier of resources (large volumes and most difficult to develop) have been the main focus of US domestic activity during recent times. Horizontal well drilling and hydraulic fracturing completion technology have been primarily responsible for this paradigm shift. The concept of drainage volume is being examined using pressure diffusion along streamlines. We use diffusive time of flight to optimize the number of hydraulic fracture stages in horizontal well application for Tight Gas reservoirs. Numerous field case histories are available in literature for optimizing number of hydraulic fracture stages, although the conclusions are case specific. In contrast, a general method is being presented that can be used to augment field experiments necessary to optimize the number of hydraulic fracture stages. The optimization results for the tight gas example are in line with the results from economic analysis. The fluid flow simulation for Naturally Fractured Reservoirs (NFR) is performed by Dual-Permeability or Dual-Porosity formulations. Microseismic data from Barnett Shale well is used to characterize the hydraulic fracture geometry. Sensitivity analysis, uncertainty assessment, manual & computer assisted history matching are integrated to develop a comprehensive workflow for building reliable reservoir simulation models. We demonstrate that incorporating proper physics of flow is the first step in building reliable reservoir simulation models. Lack of proper physics often leads to unreasonable reservoir parameter estimates. The workflow demonstrates reduced non-uniqueness for the inverse history matching problem. The behavior of near-critical fluids in Liquid Rich Shale plays defies the production behavior observed in conventional reservoir systems. In conventional reservoirs an increased gas-oil ratio is observed as flowing bottom-hole pressure is less than the saturation pressure. The production behavior is examined by building a compositional simulation model on an Eagle Ford well. Extremely high pressure drop along the multiple transverse hydraulic fractures and high critical gas saturation are responsible for this production behavior. Integrating pore-scale flow modeling (such as Lattice Boltzmann) to the field-scale reservoir simulation may enable quantifying the effects of high capillary pressure and phase behavior alteration due to confinement in the nano-pore system. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149482
Finite Conductivity Horizontal Well Fractures
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Author : Mohammed Al-Kobaisi
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2010-09
Finite Conductivity Horizontal Well Fractures written by Mohammed Al-Kobaisi 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 2010-09 with categories.
Horizontal wells are preferred in the oil and gas fields because of their effectiveness in heterogeneous reservoirs, potential in enhanced oil recovery, ability to reduce coning, and advantages in environmentally sensitive areas. For tight formations, the productivity of a horizontal well can be further increased by hydraulic fracturing. Recently, interest in improved models and understanding of fractured horizontal wells has been elevated due to their success in exploiting unconventional reservoirs, such as shale gas. This book presents a research on the transient pressure responses and modeling of horizontal wells with transverse vertical fractures. A hybrid numerical-analytical model is developed where the fracture flow is numerically simulated and dynamically coupled with an analytical solution for the reservoir flow. The hybrid model reduces the computational work while providing for incorporating the details of the fracture flow and different fractured horizontal well geometries. The book is intended for researchers as well as the practicing engineers in the areas of petroleum production and reservoir engineering, well completions, and stimulations.
Study Of Flow Regimes In Multiply Fractured Horizontal Wells In Tight Gas And Shale Gas Reservoir Systems
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Author : Craig Matthew Freeman
language : en
Publisher:
Release Date : 2010
Study Of Flow Regimes In Multiply Fractured Horizontal Wells In Tight Gas And Shale Gas Reservoir Systems written by Craig Matthew Freeman 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.
Various analytical, semi-analytical, and empirical models have been proposed to characterize rate and pressure behavior as a function of time in tight/shale gas systems featuring a horizontal well with multiple hydraulic fractures. Despite a small number of analytical models and published numerical studies there is currently little consensus regarding the large-scale flow behavior over time in such systems. The purpose of this work is to construct a fit-for-purpose numerical simulator which will account for a variety of production features pertinent to these systems, and to use this model to study the effects of various parameters on flow behavior. Specific features examined in this work include hydraulically fractured horizontal wells, multiple porosity and permeability fields, desorption, and micro-scale flow effects. The theoretical basis of the model is described in Chapter I, along with a validation of the model. We employ the numerical simulator to examine various tight gas and shale gas systems and to illustrate and define the various flow regimes which progressively occur over time. We visualize the flow regimes using both specialized plots of rate and pressure functions, as well as high-resolution maps of pressure distributions. The results of this study are described in Chapter II. We use pressure maps to illustrate the initial linear flow into the hydraulic fractures in a tight gas system, transitioning to compound formation linear flow, and then into elliptical flow. We show that flow behavior is dominated by the fracture configuration due to the extremely low permeability of shale. We also explore the possible effect of microscale flow effects on gas effective permeability and subsequent gas species fractionation. We examine the interaction of sorptive diffusion and Knudsen diffusion. We show that microscale porous media can result in a compositional shift in produced gas concentration without the presence of adsorbed gas. The development and implementation of the micro-flow model is documented in Chapter III. This work expands our understanding of flow behavior in tight gas and shale gas systems, where such an understanding may ultimately be used to estimate reservoir properties and reserves in these types of reservoirs.
Performance Comparison Of Transverse And Longitudinal Fractured Horizontal Wells Over Varied Reservoir Permeability
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Author : Fen Yang
language : en
Publisher:
Release Date : 2014
Performance Comparison Of Transverse And Longitudinal Fractured Horizontal Wells Over Varied Reservoir Permeability written by Fen Yang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Gas reservoirs categories.
"Since the first application in the mid-1980's, multiple fractured horizontal wells have proven to be an effective means of extracting hydrocarbons. These wells require careful consideration of wellbore orientation relative to the horizontal principle stress. Wellbore orientation can lead to transverse fractures which are perpendicular to the wellbore, or longitudinal fractures parallel the wellbore. Questions arise regarding whether one fracture orientation is consistently preferred over the other, or if certain conditions affect the choice. Historical work has examined the impact of horizontal wellbore azimuth in the Barnett and Marcellus Shale where public data was reviewed and statistical well analysis was conducted respectively. Comparison between transverse and longitudinal fracturing in moderate gas reservoirs has been performed with experimental study. This work includes both simulations and actual field cases studies. It compares transverse multiple fractured horizontal wells with longitudinal ones in terms of both well performance and economics. The study covers both gas and oil reservoirs and extends prior work to unconventional resources by extending the reservoir permeability to 0.00005 md. A range of reservoir permeability is identified for the preferable fracture configuration through simulations. Field production history of the Bakken, Barnett, Eagle Ford and Delaware formations are investigated and compared to the simulation results. In addition, this work analyzes the impact of fracture conductivity, lateral length, fracture half-length, completion method and hydrocarbon prices. The conclusions can be used as a reference in decision making on horizontal drilling and hydraulic fracturing for both unconventional and conventional resources"--Abstract, page iii.
Multi Frac Treatments In Tight Oil And Shale Gas Reservoirs
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Author : Abdul Muqtadir Khan
language : en
Publisher:
Release Date : 2013
Multi Frac Treatments In Tight Oil And Shale Gas Reservoirs written by Abdul Muqtadir Khan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
The vast shale gas and tight oil reservoirs in North America cannot be economically developed without multi-stage hydraulic fracture treatments. Owing to the disparity in the density of natural fractures in addition to the disparate in-situ stress conditions in these kinds of formations, microseismic fracture mapping has shown that hydraulic fracture treatments develop a range of large-scale fracture networks in the shale plays. In this thesis, an approach is presented, where the fracture networks approximated with microseismic mapping are integrated with a commercial numerical production simulator that discretely models the network structure in both vertical and horizontal wells. A novel approach for reservoir simulation is used, where porosity (instead of permeability) is used as a scaling parameter for the fracture width. Two different fracture geometries have been broadly proposed for a multi stage horizontal well, orthogonal and transverse. The orthogonal pattern represents a complex network with cross cutting fractures orthogonal to each other; whereas transverse pattern maps uninterrupted fractures achieving maximum depth of penetration into the reservoir. The response for a single-stage fracture is further investigated by comparing the propagation of the stage to be dendritic versus planar. A dendritic propagation is bifurcation of the hydraulic fracture due to intersection with the natural fracture (failure along the plane of weakness). The impact of fracture spacing to optimize these fracture geometries is studied. A systematic optimization for designing the fracture length and width is also presented. The simulation is motivated by the oil window of Eagle Ford shale formation and the results of this work illustrate how different fracture network geometries impact well performance, which is critical for improving future horizontal well completions and fracturing strategies in low permeability shale and tight oil reservoirs. A rate transient analysis (RTA) technique employing a rate normalized pressure (RNP) vs. superposition time function (STF) plot is used for the linear flow analysis. The parameters that influence linear flow are analytically derived. It is found that picking a straight line on this curve can lead to erroneous results because multiple solutions exist. A new technique for linear flow analysis is used. The ratio of derivative of inverse production and derivative of square root time is plotted against square root time and the constant derivative region is seen to be indicative of linear flow. The analysis is found to be robust because different simulation cases are modeled and permeability and fracture half-length are estimated.