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The Effects Of Acid Contact Time And Rock Surfaces On Acid Fracture Conductivity
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Book Synopsis The Effects of Acid Contact Time and Rock Surfaces on Acid Fracture Conductivity by : Maria Georgina Melendez Castillo
Download or read book The Effects of Acid Contact Time and Rock Surfaces on Acid Fracture Conductivity written by Maria Georgina Melendez Castillo and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The conductivity created in acid fracturing is a competition between two phenomena: etching of the rock surface and weakening of the rock. This study presents experimental results of acid fracturing conductivity experiments with polymer gelled acid, while varying contact time and rock type. The experiments were conducted in a laboratory facility properly scaled from field to laboratory conditions to account for the hydrodynamic effects that take place in the field. The rocks of study were Indiana limestone, San Andres dolomite and Texas Cream chalk. Our results illustrate that acid fracturing conductivity is governed by the etching pattern of the rock surface and influenced by the hardness of the rock. If channels are created, the fracture is more likely to retain conductivity after closure. The hardness of the rock is the dominating factor to determine the conductivity response when no channeling is present. Among the rocks tested, Texas Cream chalk had the lowest hardness measurement before and after acidizing and the fracture closed at a much lower stress compared with limestone and dolomite. Dolomite had the highest conductivity under all closure stresses even without a channeling pattern. Additionally, it was observed that a higher reduction in rock strength at the contact points for dolomite yielded lower conductivity after closure. The effects of hardness variation on conductivity are higher in dolomite than in limestone and chalk. It is apparent that longer contact times do not always provide higher conductivity after closure.
Book Synopsis Acid Fracture and Fracture Conductivity Study of Field Rock Samples by : Jarrod Thomas Underwood
Download or read book Acid Fracture and Fracture Conductivity Study of Field Rock Samples written by Jarrod Thomas Underwood 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 well stimulation strategy designed to increase the productivity of a producing well. The parameters of acid fracturing and the effects of acid interaction on specific rock samples can be studied experimentally. Acid injection data and fracture conductivity measurements obtained in the research presented in this thesis yielded results that qualified and quantified the impact of a specific acid system on rock samples of varying acid solubility. Six rock samples from a carbonate reservoir were labeled A through F to protect proprietary information included in this research. A 2% potassium chloride solution was used for the acid system and fracture conductivity measurements to prevent clay swelling. Injection temperature, contact time, and injection rate were designed to simulate field treatment conditions. The effects of a chelating agent on fracture conductivity were also studied. Before and after images of the rock samples indicated that the effect of 15% hydrochloric acid on the samples was limited but correlated with the rock acid solubility. Samples E and F had a greater value of acid solubility and showed noticeable surface etching. Samples A, B, and C had lower values of acid solubility and did not show signs of surface etching. Sample D was of moderate acid solubility and showed minimal signs of surface etching. Fracture conductivity did not correlate directly with acid solubility, but likely was a function of inherent matrix permeability based on leak-off measurements and fracture conductivity measurements. Finally, the fracture conductivity of Sample D increased after exposure to a chelating agent. Commonly, acid fracture experimental studies are carried out with outcrop rock samples. The samples have more homogenous properties and without hydrocarbon content. In this study, cores from downhole formation were used. The original condition was preserved as much as possible to simulate real field situations. However, using field rock samples does present challenges not generally associated with outcrop rock samples. Based on the information gathered from the work presented in this thesis, conclusions were drawn concerning the effectiveness of a 15% hydrochloric acid treatment in this formation and the challenges of using field rock samples. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151691
Book Synopsis The Effects of Initial Condition of Fracture Surfaces, Acid Spending, and Type on Conductivity of Acid Fracture by : Ali Mansour A. Almomen
Download or read book The Effects of Initial Condition of Fracture Surfaces, Acid Spending, and Type on Conductivity of Acid Fracture written by Ali Mansour A. Almomen and published by . This book was released on 2013 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture conductivity and the effects of treatment variables can be studied in the laboratory. We conducted experiments based on scaling down the field conditions to laboratory scale by matching Reynold's and Peclet numbers. Experiments conducted were comprised of three stages: dynamic etching, surface characterization of etched cores, and conductivity measurement. The effect of initial condition of fracture surfaces on the etching pattern and conductivity were investigated in this study. Another area of interest is the variation of conductivity along the fracture due to acid spending. We also investigated the contact time, acid system type, and treatment temperature effects on conductivity using San Andres dolomite cores. The results from these studies showed that rough-surface fractures generate higher conductivity by an order of magnitude compared with a smooth-surface fracture at low-closure stress. Also, conductivity generated on rough-surface fractures by smoothing peaks and deepening valleys which widen the gap between the fracture surfaces after closure and acid creates conductivity on smooth-surface fractures by differential etching that creates asperities. The results suggest that an increase in acid spending does not automatically result in lower conductivity; and etched volume alone is not adequate to predicate the conductivity. Conductivity results from a combination of etching pattern, etched volume, and rock compressive strength after etching. In-situ crosslinked acid was found to be more effective in etching rock and controlling acid leakoff compared with linear-gelled acid. Also, crosslinked acid reduces the number of pits and the pit diameters. Based on conductivity tests, linear-gelled acid is more favorable at higher temperatures while in-situ crosslinked acid showed higher conductivity at lower temperatures. For a rough-surface fracture, shorter contact time created high conductivity compared to longer contact while injecting the same volume of acid, suggesting the existence of an optimum contact time. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151186
Book Synopsis Experimental Study of Acid Fracture Conductivity of Austin Chalk Formation by : Andrea Nino Penaloza
Download or read book Experimental Study of Acid Fracture Conductivity of Austin Chalk Formation written by Andrea Nino Penaloza and published by . This book was released on 2013 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acid fracture conductivity and the effect of key variables in the etching process during acid fracturing can be assessed at the laboratory scale. This is accomplished by using an experimental apparatus that simulates acid injection fluxes comparable to those in actual acid fracture treatments. After acid etching, fracture conductivity is measured at different closure stresses. This research work presents a systematic study to investigate the effect of temperature, rock-acid contact time and initial condition of the fracture surfaces on acid fracture conductivity in the Austin Chalk formation. While temperature and rock-acid contact are variables normally studied in fracture conductivity tests, the effect of the initial condition of the fracture surface has not been extensively investigated. The experimental results showed that there is no significant difference in acid fracture conductivity at high closure stress using smooth or rough fracture surfaces. In addition, we analyzed the mechanisms of acid etching and resulting conductivity creation in the two types of fracture surfaces studied by using surface profiles. For smooth surfaces, the mechanism of conductivity creation seems connected to uneven etching of the rock and roughness generation. For rough surfaces, acid conductivity is related to smoothing and deepening of the initial features on the sample surface than by creating more roughness. Finally, we compared the experimental results with Nirode-Kruk correlation for acid fracture conductivity. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149578
Book Synopsis Laboratory-scale Fracture Conductivity Created by Acid Etching by : Maysam Pournik
Download or read book Laboratory-scale Fracture Conductivity Created by Acid Etching written by Maysam Pournik and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Success of acid fracturing treatment depends greatly on the created conductivity under closure stress. In order to have sufficient conductivity, the fracture face must be non-uniformly etched while the fracture strength maintained to withstand the closure stress. While there have been several experimental studies conducted on acid fracturing, most of these have not scaled experiments to field conditions and did not account for the effect of rock weakening and etching pattern. Hence, acid fracture conductivity predictions based on the above works have not been able to match actual results. In order to develop a more appropriate and accurate prediction of acid fracturing treatment outcome, a laboratory facility was developed that is properly scaled to field conditions and enables analysis of etching pattern and rock strength. A systematic experimental study that covered a variety of formations, acid types, and acid contact times was conducted. An acid fracture conductivity correlation was developed based on etched volume, etched pattern, and fracture strength under closure stress. Results suggested that there is an optimal time of acid exposure resulting in maximum fracture conductivity. There were large differences in the conductivity created with the different acid systems tested due to different etching patterns and degree of rock strength weakening. There was an optimal acid system depending on formation type, contact time and overburden stress. The acid fracture conductivities measured did not agree with the predictions of the Nierode-Kruk correlation. The newly developed correlation predicts conductivity much closer as it includes the effect of rock strength and surface etching pattern on resulting conductivity.
Book Synopsis Modeling Acid Transport and Non-uniform Etching in a Stochastic Domain in Acid Fracturing by : Jianye Mou
Download or read book Modeling Acid Transport and Non-uniform Etching in a Stochastic Domain in Acid Fracturing written by Jianye Mou and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis JPT. Journal of Petroleum Technology by :
Download or read book JPT. Journal of Petroleum Technology written by and published by . This book was released on 2007-07 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SPE Journal written by and published by . This book was released on 1999 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Properties and Uses of Microemulsions by : Desiree Nedra Karunaratne
Download or read book Properties and Uses of Microemulsions written by Desiree Nedra Karunaratne and published by BoD – Books on Demand. This book was released on 2017-05-24 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Properties and Uses of Microemulsions is intended to provide the reader with some important applications and features of these systems. The intricate composition of microemulsions has made them applicable in many areas such as cosmetics, pharmaceuticals, food, agriculture, oil recovery, chemical synthesis of nanoparticles, and catalysts. An introductory chapter starts off with the description of these applications followed by methods of characterization. Thereafter, a few practical applications of microemulsions focusing on drug delivery, oil recovery, and formation of nanocatalysts are described followed by the third section discussing the theoretical and physical parameters predicting microemulsion properties. The use of spin-polarized paramagnetic probes, bending energetics, and study of self-propelled motion are some of the physical parameters employed to characterize the microemulsions.
Download or read book SPE Production & Operations written by and published by . This book was released on 2006 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SPE Production & Facilities written by and published by . This book was released on 2001 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydraulic Fracturing by : Michael Berry Smith
Download or read book Hydraulic Fracturing written by Michael Berry Smith and published by CRC Press. This book was released on 2015-12-16 with total page 793 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic Fracturing effectively busts the myths associated with hydraulic fracturing. It explains how to properly engineer and optimize a hydraulically fractured well by selecting the right materials, evaluating the economic benefits of the project, and ensuring the safety and success of the people, environment, and equipment. From data estimation
Book Synopsis Acid Fracturing Feasibility Study for Heterogeneous Carbonate Formation by : Assiya Suleimenova
Download or read book Acid Fracturing Feasibility Study for Heterogeneous Carbonate Formation written by Assiya Suleimenova and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Acid fracturing is a stimulation technique that is commonly used by the industry to increase productivity or injectivity of wells in carbonate reservoirs. To determine a feasibility of acid fracturing treatment for a heterogeneous formation, the effect of rock properties on the created fracture conductivity needs to be investigated experimentally. In this study, the influence of rock lithology, porosity, and permeability on the resultant fracture conductivity was investigated for the Middle Canyon formation. Six carbonate cores collected from different depths of Middle Canyon interval were selected for this study. The cores had the permeability ranging from 0.07 to 28 md and the porosity ranging from 1.7 to 15.4%. The acid etching experimental conditions, such as injection rate, reaction temperature, and acid type, were selected to simulate field treatment conditions. The fracture surface of each sample was scanned before and after the acid treatment to characterize the change in surface profile and to calculate the etched volume of rock. The results of the study indicated that the final conductivity values under the maximum closure stress of 4000 psi were similar to each other (6.4 - 13.5 md-ft) for all the cores, regardless the variation in cores' porosity and permeability. It was also observed that the cores with a lower porosity had a lower decline rate of acid fracture conductivity with increasing closure stress. Based on the results of this study, it was concluded that acid fracturing stimulation of the Middle Canyon formation may not be effective to achieve the goals defined by the operator. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155028
Book Synopsis Improvement of Fracture Conductivity Through Study of Proppant Transport and Chemical Stimulation by : Songyang Tong
Download or read book Improvement of Fracture Conductivity Through Study of Proppant Transport and Chemical Stimulation written by Songyang Tong and published by . This book was released on 2019 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: During hydraulic fracturing treatments, proppants – usually sand – are placed inside fractures to improve fracture conductivity. However, a large portion of the generated hydraulic fractures often remain unpropped after fracturing treatments. There are two primary reasons for this poor proppant placement. First, proppants settle quickly in common fracturing fluids (e.g., slickwater), which results in unpropped sections at the tip or top of the fracture. Second, a large number of the microfractures are too narrow to accommodate any common commercial proppant. Such unpropped fractures hold a large potential flow capacity as they exhibit a large contact area with the reservoir. However, their potential flow capacity is diminished during production due to closing of unpropped fractures because of closure stress. In this study, fractures are categorized as wider fractures, which are accessible to proppant, and narrower fractures, which are inaccessible to proppant. For wider fractures, proppant transport is important as proppant is needed for keeping them open. For narrower fractures, a chemical formulation is proposed as there is less physical restriction for fluids to flow inside across them. The chemical formulation is expected to improve fracture conductivity by generating roughness on fracture surfaces. This dissertation uses experiments and simulations to investigate proppant transport in a complex fracture network with laboratory-scale transparent fracture slots. Proppant size, injection flow rate and bypass fracture angle are varied and their effects are systematically evaluated. Based on experimental results, a straight-line relationship can be used to quantify the fraction of proppant that flows into bypass fractures with the total amount of proppant injected. A Computational Fluid Dynamics (CFD) model is developed to simulate the experiments; both qualitative and quantitative matches are achieved with this model. It is concluded that the fraction of proppant which flows into bypass fractures could be small unless a significant amount of proppant is injected, which indicates the inefficiency of slickwater in transporting proppant. An alternative fracturing fluid – foam – has been proposed to improve proppant placement because of its proppant carrying capacity. Foam is not a single-phase fluid, and it suffers liquid drainage with time due to gravity. Additionally, the existence of foam bubbles and lamellae could alter the movement of proppants. Experiments and simulations are performed to evaluate proppant placement in field-scale foam fracturing application. A liquid drainage model and a proppant settling correlation are developed and incorporated into an in-housing fracturing simulator. Results indicate that liquid drainage could negatively affect proppant placement, while dry foams could lead to negligible proppant settling and consequently uniform proppant placement. For narrower fractures, two chemical stimulation techniques are proposed to improve fracture conductivity by increasing fracture surface roughness. The first is a nanoparticle-microencapsulated acid (MEA) system for shale acidizing applications, and the second is a new technology which can generate mineral crystals on the shale surface to act as in-situ proppants. The MEA could be released as the fracture closes and the released acid could etch the surface of the rock locally, in a non-uniform way, to improve fracture conductivity (up to 40 times). Furthermore, the in-situ proppant generation technology can lead to crystal growth in both fracking water and formation brine conditions, and it also improves fracture conductivity (up to 10 times) based on core flooding experiments
Book Synopsis Acid fracture conductivity of the Clearfork Formation by : Mirza Shoaib Beg
Download or read book Acid fracture conductivity of the Clearfork Formation written by Mirza Shoaib Beg and published by . This book was released on 1993 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Rock Fractures and Fluid Flow by : National Research Council
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1998 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
