A Study Of The Effect Of Stress And Fluid Sensitivity On Propped Fracture Conductivity In Preserved Reservoir Shales

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A Study of the Effect of Stress and Fluid Sensitivity on Propped Fracture Conductivity in Preserved Reservoir Shales

Author : John Wesley Pedlow
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (87 download)

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Book Synopsis A Study of the Effect of Stress and Fluid Sensitivity on Propped Fracture Conductivity in Preserved Reservoir Shales by : John Wesley Pedlow

Download or read book A Study of the Effect of Stress and Fluid Sensitivity on Propped Fracture Conductivity in Preserved Reservoir Shales written by John Wesley Pedlow and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A sizable amount of literature exists analyzing the effect of confining stress on fracture conductivity in sandstones. This thesis attempts to answer similar questions with regard to shale formations. The low Young's Moduli and Brinell hardness values characteristic of many prospective shale formations may lead to a great deal of embedment and fines production which can drastically reduce fracture conductivity. Furthermore, shales exhibit sensitivity to aqueous fluids which may cause them to be weakened in the presence of certain fracturing fluids. Previous work analyzing shale fluid sensitivity has failed to preserve the shales' formation properties by allowing the shale to dry out. This paper presents a study of propped fracture conductivity experiments at reservoir temperature and pressure using various North American shale reservoir cores. Exposure to the atmosphere can alter the mechanical properties of the shale by either drying or hydrating the samples, so care was taken to preserve these shales in their native state by maintaining constant water activity (relative humidity). Variations in applied closure stress and aqueous fluid exposure were analyzed and in certain cases altered the propped fracture conductivity by crushing proppant, embedding the proppant into the fracture face, and producing fines. The damage to fracture conductivity is correlated to mineralogy for the various shale samples. These findings show that a one-size-fits-all frac design will not work in every shale formation, rather a tailored approach to each shale is necessary. In the future, the results of this work will be analyzed alongside easier to perform Brinell hardness tests, swelling tests, and other characterization techniques incorporated into the UT Shale Characterization Protocol. Correlations were developed to relate the simpler tests to the fracture conductivity experiments which yield a straight forward method to determine the role embedment and fluid sensitivity have on post treatment fracture conductivity in shales. The UT Shale characterization Protocol can then be used to optimize the design and execution of fracing treatments.

Experimental Study of the Effect of Stress and Fluid Sensitivity on Propped and Un-propped Fracture Conductivity in Preserved Reservoir Shale

Download Experimental Study of the Effect of Stress and Fluid Sensitivity on Propped and Un-propped Fracture Conductivity in Preserved Reservoir Shale PDF Online Free

Author : Pratik Kakkar
Publisher :
ISBN 13 :
Total Pages : 130 pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis Experimental Study of the Effect of Stress and Fluid Sensitivity on Propped and Un-propped Fracture Conductivity in Preserved Reservoir Shale by : Pratik Kakkar

Download or read book Experimental Study of the Effect of Stress and Fluid Sensitivity on Propped and Un-propped Fracture Conductivity in Preserved Reservoir Shale written by Pratik Kakkar and published by . This book was released on 2016 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: A good amount of work has been done on analyzing the effect of stress and fluid sensitivity on fracture conductivity in sandstones. This thesis tries to answer similar questions with regard to shale formations. Shales are very sensitive to aqueous fluids and their mechanical properties change when exposed to it. This mechanical property change in shale is mainly caused due to clay swelling. Some of the previous researchers working on shale fluid sensitivity failed to use preserved reservoir cores for their experiments and allowed them to dry out. This study has been conducted on preserved Utica and Eagle Ford core samples. Experiments were conducted to study the effect of effective stress on propped and un-propped fracture conductivity. These experiments were conducted at reservoir temperature and pressure conditions to mimic field conditions. Different fluids were flowed through the fracture to compare the effect of different fluids on fracture conductivity. To prevent clay swelling various clay stabilizers are used in the field during drilling and fracturing operations. Experiments were conducted to test the effectiveness of different clay stabilizers in preventing fracture conductivity reduction. Some of the clay stabilizers were more effective than others but all of them were unable to prevent fracture conductivity reduction when fracture was flowed with a high pH fluid.

Unpropped Fractures in Shale

Author : Weiwei Wu (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis Unpropped Fractures in Shale by : Weiwei Wu (Ph. D.)

Download or read book Unpropped Fractures in Shale written by Weiwei Wu (Ph. D.) and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large proportion of the hydraulic fractures created during a hydraulic fracturing treatment remain unpropped after hydraulic fracturing despite the significant quantities of proppant injected in the process. These fractures either have a fracture width smaller than the size of the proppants, or are too far away from the wellbore where proppant cannot reach. Their presence has been demonstrated and corroborated by multiple independent sources of evidence such as flowback, production and microseismic data. These unpropped fractures present a huge potential for production enhancement, since they possess a very large contact area with the reservoir. Unfortunately, this potential flow area is closed by the closure stress during production. Without the presence of proppants, unpropped fractures are expected to behave differently from propped fractures. In this study, fracture conductivities of unpropped fractures in shales are measured with preserved Eagle Ford and Utica shale cores to better understand their closure behavior, in particular those after exposure to fracturing fluids. The unpropped fractures exhibit fracture conductivities 2 to 4 orders of magnitude lower than those of propped fractures, and are more sensitive to closure stress. Plastic deformation is found to dominate the closure process, and strong hysteresis occurs in unpropped fracture conductivity with a 70-80% reduction after a loading-unloading cycle of closure stress. Exposure to water-based fracturing fluids reduces unpropped fracture conductivity by shale softening or fines production. Unpropped fracture conductivities also appear to be sensitive to shale mineralogy, which affects the shale mechanical properties and shale-fluid interaction. A numerical model is developed to simulate the closure of unpropped and natural fractures, and to compute their corresponding fracture conductivity. A conjugate gradient algorithm and fast Fourier transform technique are incorporated to dramatically enhance the computation efficiency. Plastic deformation and deformation interaction among asperities, ignored in some previous models, are considered and shown to play an important role in the closure process. The model is validated against analytical solutions and experiments, for both elastic-only and elastoplastic scenarios. The compliance of unpropped fractures is demonstrated to be sensitive to the roughness and hardness of fracture surfaces, while less affected by Young's modulus. The new model is also capable of simulating closure of heterogeneous fracture surfaces. More plastic deformation and lower fracture conductivity is measured when surfaces with high clay content are used. Given the same mineralogy, the mineral distribution pattern shows a smaller impact on the closure behavior. The possibility of employing acid fracturing to stimulate unpropped fractures is also explored. The acid-etched topography of shale fracture surfaces is found to be dependent on both the content and distribution of the carbonate minerals. Shales with a high carbonate content (over 60 wt%) generally tend to develop rougher acid-etched surfaces. However, more carbonate content does not always necessarily lead to increased etched roughness. High etched roughness is more likely developed from a blocky, rather than scattered, distribution of carbonate minerals. A new experimental method, the "half-core approach", is formulated to address the challenge caused by shale heterogeneity in experimentally evaluating and comparing fracture performance. The half-core approach splits one shale core into two half cores, which are then subjected to treatments of interest independently, followed by assemblage into individual full cores with a spacer for fracture conductivity measurement. The half-core approach is effective in creating a baseline with reduced sample variation among shales to improve evaluation of fracturing fluids. Similar mineralogy and mechanical properties are found between half-cores among preserved shale samples spanning a wide range of mineralogy from Barnett, Eagle Ford, Haynesville and Utica shales. By applying the half-core approach, acid fracturing is systematically benchmarked against brine with Eagle Ford shales categorized into low (below 40 wt%), medium (40-70 wt%) and high (over 70 wt%) carbonate content. Compared to brine exposure, non-uniform acid fracturing enhances unpropped fracture conductivities for shales for a wide range of carbonate contents, while uniform acid fracturing generally leads to lower fracture conductivities due to shale softening. The unetched zone in non-uniform etching reduces shale softening and creates a surface topography that enhances fracture flow. Channels are more likely to form in carbonate-rich shale (over 70 wt%). Development of channels substantially increases the unpropped fracture conductivity, and reduces the hysteresis of unpropped fracture conductivities to closure stress. The presence of carbonate veins is found to promote the development of non-uniform etching

Experimental Investigation of Propped Fracture Conductivity in Tight Gas Reservoirs Using The Dynamic Conductivity Test

Author : Jose Domingo Romero Lugo
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (865 download)

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Book Synopsis Experimental Investigation of Propped Fracture Conductivity in Tight Gas Reservoirs Using The Dynamic Conductivity Test by : Jose Domingo Romero Lugo

Download or read book Experimental Investigation of Propped Fracture Conductivity in Tight Gas Reservoirs Using The Dynamic Conductivity Test written by Jose Domingo Romero Lugo and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic Fracturing stimulation technology is used to increase the amount of oil and gas produced from low permeability reservoirs. The primary objective of the process is to increase the conductivity of the reservoir by the creation of fractures deep into the formation, changing the flow pattern from radial to linear flow. The dynamic conductivity test was used for this research to evaluate the effect of closure stress, temperature, proppant concentration, and flow back rates on fracture conductivity. The objective of performing a dynamic conductivity test is to be able to mimic actual field conditions by pumping fracturing fluid/proppant slurry fluid into a conductivity cell, and applying closure stress afterwards. In addition, a factorial design was implemented in order to determine the main effect of each of the investigated factors and to minimize the number of experimental runs. Due to the stochastic nature of the dynamic conductivity test, each experiment was repeated several times to evaluate the consistency of the results. Experimental results indicate that the increase in closure stress has a detrimental effect on fracture conductivity. This effect can be attributed to the reduction in fracture width as closure stress was increased. Moreover, the formation of channels at low proppant concentration plays a significant role in determining the final conductivity of a fracture. The presence of these channels created an additional flow path for nitrogen, resulting in a significant increase in the conductivity of the fracture. In addition, experiments performed at high temperatures and stresses exhibited a reduction in fracture conductivity. The formation of a polymer cake due to unbroken gel dried up at high temperatures further impeded the propped conductivity. The effect of nitrogen rate was observed to be inversely proportional to fracture conductivity. The significant reduction in fracture conductivity could possibly be due to the effect of polymer dehydration at higher flow rates and temperatures. However, there is no certainty from experimental results that this conductivity reduction is an effect that occurs in real fractures or whether it is an effect that is only significant in laboratory conditions. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148364

The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs

Author : Anton Nikolaev Kamenov
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (868 download)

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Book Synopsis The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs by : Anton Nikolaev Kamenov

Download or read book The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs written by Anton Nikolaev Kamenov and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracture conductivity in ultra-low permeability shale reservoirs is directly related to well productivity. The main goal of hydraulic fracturing in shale formations is to create a network of conductive pathways in the rock which increase the surface area of the formation that is connected to the wellbore. These highly conductive fractures significantly increase the production rates of petroleum fluids. During the process of hydraulic fracturing proppant is pumped and distributed in the fractures to keep them open after closure. Economic considerations have driven the industry to find ways to determine the optimal type, size and concentration of proppant that would enhance fracture conductivity and improve well performance. Therefore, direct laboratory conductivity measurements using real shale samples under realistic experimental conditions are needed for reliable hydraulic fracturing design optimization. A series of laboratory experiments was conducted to measure the conductivity of propped and unpropped fractures of Barnett shale using a modified API conductivity cell at room temperature for both natural fractures and induced fractures. The induced fractures were artificially created along the bedding plane to account for the effect of fracture face roughness on conductivity. The cementing material present on the surface of the natural fractures was preserved only for the initial unpropped conductivity tests. Natural proppants of difference sizes were manually placed and evenly distributed along the fracture face. The effect of proppant monolayer was also studied. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149386

Conductivity Evolution in Propped Fractures During Reservoir Drawdown

Author : Jiayi Yu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Conductivity Evolution in Propped Fractures During Reservoir Drawdown by : Jiayi Yu

Download or read book Conductivity Evolution in Propped Fractures During Reservoir Drawdown written by Jiayi Yu and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate the evolution of` fracture conductivity as a function of proppant loading concentration under varying effective stresses as an analog to reservoir drawdown. In particular, we define the relative impacts and interplay between proppant crushing, proppant embedment, compaction and particle rearrangement and their impacts on fluid transport. Proppant of realistic concentrations is sandwiched between split core-plugs of Marcellus shale that accommodates embedment as well as rigid steel that excludes it. Impacts of proppant crushing and embedment and roles of particulate transport in fracturing-fluid clean-up are defined. Experiments are performed under triaxial stresses with independent control on confining stress and pore pressure. Normal loading is incremented to represent reservoir drawdown with conductivity evolution recorded continuously via flow-through of brine (20,000 mg/L KCl). Proppant embedment is characterized pre- and post-test by white light optical profilometry with pre-and post-test particle size distributions of the proppant defining the impact of proppant crushing. The conductivity of propped fractures decreases by up to 95% as effective stress is increased by 50 MPa (7000 psi). This reduction is broadly independent of whether the fracture walls are rigid or deformable. The stress-sensitivity of conductivity is generally muted with increasing proppant loading concentration. We normalize fracture conductivities to equivalent permeabilities of the proppant pack to directly compare pack permeabilities. Low proppant concentrations return higher permeability at low effective stresses but lower permeability at high effective stress, relative to high proppant concentrations. This results since proppant crushing and embedment are both mitigated with increasing proppant loading concentration, as more displacement degree of freedom are added to the system and provide accommodation for interior compaction and rearrangement. Extended effective stress holding times (24h vs

Shale Fracturing Enhancement by Using Polymer-free Foams and Ultra-light Weight Proppants

Author : Ming Gu
Publisher :
ISBN 13 :
Total Pages : 546 pages
Book Rating : 4.:/5 (94 download)

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Book Synopsis Shale Fracturing Enhancement by Using Polymer-free Foams and Ultra-light Weight Proppants by : Ming Gu

Download or read book Shale Fracturing Enhancement by Using Polymer-free Foams and Ultra-light Weight Proppants written by Ming Gu and published by . This book was released on 2013 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Slickwater with sand is the most commonly used hydraulic fracturing treatment for shale reservoirs. The slickwater treatment produces long skinny fractures, but only the near wellbore region is propped due to fast settling of sand. Adding gel into water can prevent the fast settling of sand, but gel may damage the fracture surface and proppant pack. Moreover, current water-based fracturing consumes a large amount of water, has high water leakage, and imposes high water disposal costs. The goal of this project is to develop non-damaging, less water-intensive fracturing treatments for shale gas reservoirs with improved proppant placement efficiency. Earlier studies have proposed to replace sand with ultra-light weight proppants (ULWP) to enhance proppant transport, but it is not used commonly in field. This study evaluates the performance of three kinds of ULWPs covering a wide range of specific gravity and representing the three typical manufacturing methods. In addition to replacing sand with ULWPs, replacing water with foams can be an alternative treatment that reduces water usage and decreases proppant settling. Polymer-added foams have been used in conventional reservoirs to improve proppant placement efficiency. However, polymers can damage shale permeability in unconventional reservoirs. This dissertation studies polymer-free foams (PFF) and evaluates their performance. This study uses both experiments and simulations to assess the productivity and profitability of the ULWP treatment and PFF treatment. First, a reservoir simulation model is built in CMG to study the impact of fracture conductivity and propped length on fracture productivity. This model assumes a single fracture intersecting a few reactivated natural fractures. Second, a 2D fracturing model is used to simulate the fracture propagation and proppant transport. Third, strength, API conductivity and gravity settling rates are measured for three ULWPs. Fourth, foam stability tests are conducted to screen the best PFF agents and the selected foams are put into a circulating loop to study their rheology. Finally, empirical correlations from the experiments are applied in the fracturing model and reservoir model to predict productivity by using the ULWPs with slickwater or using the PFFs with sand. Experimental results suggest that, at 4000 psi with concentrations varying from partial monolayer (0.05 lb/ft2) to multilayer (1 lb/ft2), ULW-1 (polymeric) is the most deformable with conductivity of 1-10 md-ft. ULW-2 (resin coated and impregnated ground walnut hull) is the second most deformable with similar conductivity. ULW-3 (resin coated porous ceramic) is the least deformable with conductivity of 20-1000 md-ft, which is comparable to sand. Three foam formulations (A, B: regular surfactant foam, C: viscoelastic surfactant foam) are selected based on the stability results of fourteen surfactants. All PFFs exhibit power-law rheological behavior in a laminar flow regime. The power law parameters of the regular surfactant PFF depend on both quality and pressure when quality is higher than 60% but depend on quality only when quality is lower than 60%. Simulation results suggest that under the optimal concentration of 0.04-0.06 v/v (0.37-0.55 lb/gal) for both ULW-1 and ULW-2, and 0.1 v/v (1.46 lb/gal) for ULW-3, 1-year cumulative production for 0.1 [mu]D shale reservoir is higher than sand by 127% for ULW-1, 28% for ULW-2, and 38% for ULW-3. The productivity benefits decrease as shale permeability increases for all three ULWPs. ULW-1 and ULW-2 have higher productivity benefits for longer production time, while ULW-3 has relatively constant productivity benefits over time. The economic profit of ULW-1 when priced at $5/lb is 2.2 times larger than that of sand for 1-year production in 0.1 [mu]D shale reservoirs; the acceptable maximum price is $10/lb for ULW-1, $6/lb for ULW-2, and $2.5/lb for ULW-3. The maximum price increases as production time increases. The PFFs with a quality of 60% carrying mesh 40 sand at a partial monolayer concentration of 0.04 v/v (0.88 lb/gal) can generate 50% higher productivity, 74% higher economic profit, and over 300% higher water efficiency than the best slickwater-sand case (mesh 40 sand at 0.1 v/v) for 1-year production in 0.1[mu]D shale reservoirs. The benefits of using the PFFs decrease with increasing shale permeability, increasing production time, or decreasing pumping time. This dissertation gives a range of field conditions where the ULWP and PFF may be more effective than slickwater-sand fracturing.

The Effects of Fracture Orientation and Anisotropy on Hydraulic Fracture Conductivity in the Marcellus Shale

Author : Mark John McGinley
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (942 download)

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Book Synopsis The Effects of Fracture Orientation and Anisotropy on Hydraulic Fracture Conductivity in the Marcellus Shale by : Mark John McGinley

Download or read book The Effects of Fracture Orientation and Anisotropy on Hydraulic Fracture Conductivity in the Marcellus Shale written by Mark John McGinley and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Production of hydrocarbons from low-permeability shale reservoirs has become economically feasible thanks in part to advances in horizontal drilling and hydraulic fracturing. Together, these two techniques help to create a network of highly-permeable fractures, which act as fluid conduits from the reservoir to the wellbore. The efficacy of a fracturing treatment can best be determined through fracture conductivity analysis. Fracture conductivity is defined as the product of fracture permeability and fracture width, and describes both how much and how easily fluid can flow through fractures. It is therefore directly related to well performance. The goal of this work is to explore fracture conductivity of Marcellus shale samples fractured in both horizontal and vertical orientations. The Marcellus shale, located primarily in Pennsylvania, Ohio, West Virginia, New York, and Maryland, is the largest gas-bearing shale formation in North America, and its development has significant implications on regional economies, the northeast United States' energy infrastructure, and the availability of petrochemical plant feedstock. In this work, a series of experiments was conducted to determine the propped fracture conductivity of 23 different samples from Elimsport and Allenwood, Pennsylvania. Before conductivity measurements were taken, the pedigree of samples was verified through XRD analysis, elastic rock properties were measured and compared against literature values, and fracture surface contours were mapped and measured. Fracture conductivity of both horizontally and vertically-fracture samples was determined by measuring the pressure drop of nitrogen gas through a modified API conductivity cell. Results show that fracture conductivity varies as a function of fracture orientation only when anisotropy of the rock's mechanical properties is pronounced. It is hypothesized that the anisotropy of Young's Modulus and Poisson's Ratio play a significant role in fracture mechanics, and therefore in the width of hydraulically-induced fractures. Ultimately, the experiments conducted as part of this work show that fracture conductivity trends are strongly tied to both proppant concentration and the rock's mechanical properties. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155300

The Influence of Vertical Location on Hydraulic Fracture Conductivity in the Fayetteville Shale

Author : Kathryn Elizabeth Briggs
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (92 download)

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Book Synopsis The Influence of Vertical Location on Hydraulic Fracture Conductivity in the Fayetteville Shale by : Kathryn Elizabeth Briggs

Download or read book The Influence of Vertical Location on Hydraulic Fracture Conductivity in the Fayetteville Shale written by Kathryn Elizabeth Briggs and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracturing is the primary stimulation method within low permeability reservoirs, in particular shale reservoirs. Hydraulic fracturing provides a means for making shale reservoirs commercially viable by inducing and propping fracture networks allowing gas flow to the wellbore. Without a propping agent, the created fracture channels would close due to the in-situ stress and defeat the purpose of creating induced fractures. The fracture network conductivity is directly related to the well productivity; therefore, the oil and gas industry is currently trying to better understand what impacts fracture conductivity. Shale is a broad term for a fine-grained, detrital rock, composed of silts and clays, which often suggest laminar, fissile structure. This work investigates the difference between two vertical zones in the Fayetteville shale, the FL2 and FL3, by measuring laboratory fracture conductivity along an artificially induced, rough, aligned fracture. Unpropped and low concentration 30/70 mesh proppant experiments were run on samples from both zones. Parameters that were controllable, such as proppant size, concentration and type, were kept consistent between the two zones. In addition to comparing experimental fracture conductivity results, mineral composition, thin sections, and surface roughness scans were evaluated to distinguish differences between the two zones rock properties. To further identify differences between the two zones, 90-day production data was analyzed. The FL2 consistently recorded higher conductivity values than the FL3 at closure stress up to 3,000 psi. The mineral composition analysis of the FL2 and FL3 samples concluded that although the zones had similar clay content, the FL2 contained more quartz and the FL3 contained more carbonate. Additionally, the FL2 samples were less fissile and had larger surface fragments created along the fracture surface; whereas the FL3 samples had flaky, brittle surface fragments. The FL2 had higher conductivity values at closure stresses up to 3,000 psi due to the rearrangement of bulky surface fragments and larger void spaces created when fragments were removed from the fracture surface. The conductivity difference between the zones decreases by 25% when low concentration, 0.03 lb/ft2, 30/70 mesh proppant is placed evenly on the fracture surface. The conductivity difference decrease is less drastic, changing only 7%, when increase the proppant concentration to 0.1 lb/ft2 30/70 mesh proppant. In conclusion, size and brittleness of surface fracture particles significantly impacts the unpropped and low concentration fracture conductivity. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152755

Stress-dependent Fracture Conductivity of Propped Fractures in the Stimulated Reservoir Volume of a Hydraulically Fractured Shale Well

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Author : Di Zhang
Publisher :
ISBN 13 :
Total Pages : 70 pages
Book Rating : 4.:/5 (944 download)

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Book Synopsis Stress-dependent Fracture Conductivity of Propped Fractures in the Stimulated Reservoir Volume of a Hydraulically Fractured Shale Well by : Di Zhang

Download or read book Stress-dependent Fracture Conductivity of Propped Fractures in the Stimulated Reservoir Volume of a Hydraulically Fractured Shale Well written by Di Zhang and published by . This book was released on 2016 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Proppant Fracture Conductivity with High Proppant Loading and High Closure Stress

Author : Matthew Charles Rivers
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (747 download)

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Book Synopsis Proppant Fracture Conductivity with High Proppant Loading and High Closure Stress by : Matthew Charles Rivers

Download or read book Proppant Fracture Conductivity with High Proppant Loading and High Closure Stress written by Matthew Charles Rivers and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-deepwater reservoirs are important unconventional reservoirs that hold the potential to produce billions of barrels of hydrocarbons, but also present major challenges. This type of reservoir is usually high pressure and high temperature (HPHT) and has a relatively high permeability. Hydraulic fracturing high permeability reservoirs are different from the hydraulic fracturing technology used in low permeability formations. The main purpose of hydraulic fracturing in low permeability reservoirs is to create a long, highly conductive path, whereas in high permeability formations hydraulic fracturing is used predominantly to bypass near wellbore formation damage, control sand production and reduce near wellbore pressure drop. Hydraulically fracturing these types of wells requires short fractures packed with high proppant concentrations. In addition, fracturing in high permeability reservoirs aims at achieving enough fracture length to increase productivity, especially when the viscosity of the reservoir fluid is high. In order to pump such a job and ensure long term productivity from the fracture, understanding the behavior of the fracture fluid and proppant is critical. A series of laboratory experiments have been conducted to study conductivity and fracture width with high proppant loading, high temperature and high pressure. Proppant was manually placed in the fracture and fracture fluid was pumped through the pack. Conductivity was measured by pumping oil to simulate reservoir conditions. Proppant performance and fracture fluids, which carry the proppant into the fracture, and their subsequent clean-up during production, were studied. High strength proppant is ideal for deep fracture stimulations and in this study different proppant loadings at different stresses were tested to see the impact of crushing and fracture width reduction on fracture conductivity. The preliminary test results indicated that oil at reservoir conditions improves clean-up of fracture fluid left in the proppant pack compared with using water at ambient temperature. Increasing the proppant concentration in the fracture showed higher conductivity values in some cases even at high closure stress. The increase in effective closure stress with high temperature resulted in a significant loss in conductivity. Additionally, the fracture width decreased with time and increased effective closure stress. Tests were also run to study the effect of cyclic loading which is expected to further decrease conductivity.

Laboratory Study to Identify the Impact of Fracture Design Parameters Over the Final Fracture Conductivity Using the Dynamic Fracture Conductivity Test Procedure

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Author : Andres Eduardo Pieve La Rosa
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (747 download)

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Book Synopsis Laboratory Study to Identify the Impact of Fracture Design Parameters Over the Final Fracture Conductivity Using the Dynamic Fracture Conductivity Test Procedure by : Andres Eduardo Pieve La Rosa

Download or read book Laboratory Study to Identify the Impact of Fracture Design Parameters Over the Final Fracture Conductivity Using the Dynamic Fracture Conductivity Test Procedure written by Andres Eduardo Pieve La Rosa and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation carried out the analysis of fracture conductivity in a tight reservoir using laboratory experiments, by applying the procedure known as the dynamic fracture conductivity test. Considering the large number of experiments necessary to evaluate the effect of each parameter and the possible interaction of their combinations, the schedules of experiments were planned using a fractional factorial design. This design is used during the initial stage of studies to identify and discharge those factors that have little or no effect. Finally, the most important factors can then be studied in more detail during subsequent experiments. The objectives of this investigation were focused on identifying the effect of formation parameters such as closure stress, and temperature and fracture fluid parameters such as proppant loading over the final conductivity of a hydraulic fracture treatment. With the purpose of estimating the relation between fracture conductivity and the design parameters, two series of experiments were performed. The first set of experiments estimated the effects of the aliases parameters. The isolated effect of each independent parameter was obtained after the culmination of the second set of experiments. The preliminary test results indicated that the parameters with major negative effect over the final conductivity were closure stress and temperature. Some additional results show that proppant distribution had a considerable role over the final fracture conductivity when a low proppant concentration was used. Channels and void spaces in the proppant pack were detected on these cases improving the conductivity of the fracture, by creating paths of high permeability. It was observed that with experiments at temperatures around 250 degrees F, the unbroken gel dried up creating permeable scales that resulted in a significant loss in conductivity. The results of this investigation demonstrated that dynamic fracture conductivity test procedure is an excellent tool to more accurately represent the effects of design parameters over the fracture conductivity. These results are also the first step in the development of a statistical model that can be used to predict dynamic fracture conductivity.

Evaluation and Effect of Fracturing Fluids on Fracture Conductivity in Tight Gas Reservoirs Using Dynamic Fracture Conductivity Test

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Author : Juan Correa Castro
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (747 download)

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Book Synopsis Evaluation and Effect of Fracturing Fluids on Fracture Conductivity in Tight Gas Reservoirs Using Dynamic Fracture Conductivity Test by : Juan Correa Castro

Download or read book Evaluation and Effect of Fracturing Fluids on Fracture Conductivity in Tight Gas Reservoirs Using Dynamic Fracture Conductivity Test written by Juan Correa Castro and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unconventional gas has become an important resource to help meet our future energy demands. Although plentiful, it is difficult to produce this resource, when locked in a massive sedimentary formation. Among all unconventional gas resources, tight gas sands represent a big fraction and are often characterized by very low porosity and permeability associated with their producing formations, resulting in extremely low production rate. The low flow properties and the recovery factors of these sands make necessary continuous efforts to reduce costs and improve efficiency in all aspects of drilling, completion and production techniques. Many of the recent improvements have been in well completions and hydraulic fracturing. Thus, the main goal of a hydraulic fracture is to create a long, highly conductive fracture to facilitate the gas flow from the reservoir to the wellbore to obtain commercial production rates. Fracture conductivity depends on several factors, such as like the damage created by the gel during the treatment and the gel clean-up after the treatment. This research is focused on predicting more accurately the fracture conductivity, the gel damage created in fractures, and the fracture cleanup after a hydraulic fracture treatment under certain pressure and temperature conditions. Parameters that alter fracture conductivity, such as polymer concentration, breaker concentration and gas flow rate, are also examined in this study. A series of experiments, using a procedure of "dynamical fracture conductivity test," were carried out. This procedure simulates the proppant/frac fluid slurries flow into the fractures in a low-permeability rock, as it occurs in the field, using different combinations of polymer and breaker concentrations under reservoirs conditions. The result of this study provides the basis to optimize the fracturing fluids and the polymer loading at different reservoir conditions, which may result in a clean and conductive fracture. Success in improving this process will help to decrease capital expenditures and increase the production in unconventional tight gas reservoirs.

Investigation of the Effect of Gel Residue on Hydraulic Fracture Conductivity Using Dynamic Fracture Conductivity Test

Author : Fivman Marpaung
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (37 download)

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Book Synopsis Investigation of the Effect of Gel Residue on Hydraulic Fracture Conductivity Using Dynamic Fracture Conductivity Test by : Fivman Marpaung

Download or read book Investigation of the Effect of Gel Residue on Hydraulic Fracture Conductivity Using Dynamic Fracture Conductivity Test written by Fivman Marpaung and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The key to producing gas from tight gas reservoirs is to create a long, highly conductive flow path, via the placement of a hydraulic fracture, to stimulate flow from the reservoir to the wellbore. Viscous fluid is used to transport proppant into the fracture. However, these same viscous fluids need to break to a thin fluid after the treatment is over so that the fracture fluid can be cleaned up. In shallower, lower temperature (less than 250°F) reservoirs, the choice of a fracture fluid is very critical to the success of the treatment. Current hydraulic fracturing methods in unconventional tight gas reservoirs have been developed largely through ad-hoc application of low-cost water fracs, with little optimization of the process. It seems clear that some of the standard tests and models are missing some of the physics of the fracturing process in low-permeability environments. A series of the extensive laboratory "dynamic fracture conductivity" tests have been conducted. Dynamic fracture conductivity is created when proppant slurry is pumped into a hydraulic fracture in low permeability rock. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially, we pump proppant/ fracturing fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. Test results indicate that increasing gel concentration decreases retained fracture conductivity for a constant gas flow rate and decreasing gas flow rate decreases retained fracture conductivity. Without breaker, the damaging effect of viscous hydraulic fracturing fluids on the conductivity of proppant packs is significant at temperature of 150°F. Static conductivity testing results in higher retained fracture conductivity when compared to dynamic conductivity testing.

Evaluation of the Relationship Between Fracture Conductivity, Fracture Fluid Production, and Effective Fracture Length

Author : Elyezer P. Lolon
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (796 download)

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Book Synopsis Evaluation of the Relationship Between Fracture Conductivity, Fracture Fluid Production, and Effective Fracture Length by : Elyezer P. Lolon

Download or read book Evaluation of the Relationship Between Fracture Conductivity, Fracture Fluid Production, and Effective Fracture Length written by Elyezer P. Lolon and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-permeability gas wells often produce less than predicted after a fracture treatment. One of the reasons for this is that fracture lengths calculated after stimulation are often less than designed lengths. While actual fracture lengths may be shorter due to fracture growth out of zone, improper proppant settling, or proppant flowback, short calculated fracture lengths can also result from incorrect analysis techniques. It is known that fracturing fluid that remains in the fracture and formation after a hydraulic fracture treatment can decrease the productivity of a gas well by reducing the relative permeability to gas in the region invaded by this fluid. However, the relationships between fracture fluid cleanup, effective fracture length, and well productivity are not fully understood. In this work I used reservoir simulation to determine the relationship between fracture conductivity, fracture fluid production, effective fracture length, and well productivity. I simulated water saturation and pressure profiles around a propped fracture, tracked gas production along the length of the propped fracture, and quantified the effective fracture length (i.e., the fracture length under single-phase flow conditions that gives similar performance as for multiphase flow conditions), the "cleanup" fracture length (i.e., the fracture length corresponding to 90% cumulative gas flow rate into the fracture), and the"apparent" fracture length (i.e., the fracture length where the ratio of multiphase to single-phase gas entry rate profiles is unity). This study shows that the proppant pack is generally cleaned up and the cleanup lengths are close to designed lengths in relatively short times. Although gas is entering along entire fracture, fracturing fluid remains in the formation near the fracture. The water saturation distribution affects the gas entry rate profile, which determines the effective fracture length. Subtle changes in the gas rate entry profile can result in significant changes in effective fracture length. The results I derived from this work are consistent with prior work, namely that greater fracture conductivity results in more effective well cleanup and longer effective fracture lengths versus time. This study provides better explanation of mechanisms that affect fracturing fluid cleanup, effective fracture length, and well productivity than previous work.

Improvement of Fracture Conductivity Through Study of Proppant Transport and Chemical Stimulation

Author : Songyang Tong
Publisher :
ISBN 13 :
Total Pages : 360 pages
Book Rating : 4.:/5 (125 download)

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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

Petroleum Production Systems

Author : Michael J. Economides
Publisher : Pearson Education
ISBN 13 : 0137031580
Total Pages : 752 pages
Book Rating : 4.1/5 (37 download)

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Book Synopsis Petroleum Production Systems by : Michael J. Economides

Download or read book Petroleum Production Systems written by Michael J. Economides and published by Pearson Education. This book was released on 2013 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by four leading experts, this edition thoroughly introduces today's modern principles of petroleum production systems development and operation, considering the combined behaviour of reservoirs, surface equipment, pipeline systems, and storage facilities. The authors address key issues including artificial lift, well diagnosis, matrix stimulation, hydraulic fracturing and sand control. They show how to optimise systems for diverse production schedules using queuing theory, as well as linear and dynamic programming. Throughout, they provide both best practices and rationales, fully illuminating the exploitation of unconventional oil and gas reservoirs. Updates include: Extensive new coverage of hydraulic fracturing, including high permeability fracturing New sand and water management techniques * An all-new chapter on Production Analysis New coverage of digital reservoirs and self-learning techniques New skin correlations and HW flow techniques