Evaluation of Fracturing Fluid Stability by Using a Heated, Pressurized Flow Loop

1984 ◽  
Vol 24 (03) ◽  
pp. 249-255 ◽  
Author(s):  
Jaime A. Lescarboura ◽  
Thomas R. Sifferman ◽  
Harry A. Wahl
Keyword(s):  
High Temperature ◽  
Shear Rate ◽  
High Temperatures ◽  
Carrying Capacity ◽  
Test Fluid ◽  
Drilling Fluids ◽  
Flow Loop ◽  
Shear Rates ◽  
Magnetic Flowmeter ◽  
Fracturing Fluids

Abstract A flow loop was used to evaluate the stability of fracturing fluids at high temperatures. The design provides enough pressure to prevent vaporization of water-base systems up to 350F [177C]. Crosslinked polymer systems from four service companies were evaluated at 180 and 245F [82 and 118C]. The tests showed that crosslinked fracturing fluids degrade with temperature and shear, losing much of their viscosity and proppant-carrying capacity in a few hours. Thermal stability is a major factor in selecting gels for fracturing deep, high-temperature reservoirs. Introduction Job failures in deep, hot wells can be caused by "sand-outs." These sandouts, or "screenouts," can result from inadequate carrying capacity (reduced viscosity) or too high a fluid loss (dehydration) for the polymer loading of the fracturing fluid. This study investigates the reduction in viscosity of crosslinked fracturing fluids with time at temperatures and shear rates approximating downhole conditions. A flow loop was used to investigate the rheological properties of fracturing fluids as a function of time under shear at temperatures as high as 245F [118C]. The pipe loop configuration was chosen because our field experience indicated that rotational viscometers were too "kind" to fracturing systems. We experienced sandouts that should not have happened if the crosslinked fracturing systems used had the flow characteristics that rotational viscometry indicated they had. The flow loop configuration also avoids some of the problems inherent in rotational viscometers, such as fluid climbing the shaft and contamination of the sample. Flow loops have been used to condition and evaluate drilling fluids at high temperatures. However, some of these instruments were not designed to give quantitative results. Our instrument permits measurement of apparent viscosity at known shear rates, flow index, and consistency index, all at high temperatures. This paper describes the flow loop, test procedures used, and results obtained. The flow loop gives reproducible results at high temperatures and allows the evaluation of the rheological properties of fracturing fluids under flow conditions nearer those encountered in actual fracturing jobs than do rotational, high-temperature instruments. Previous Work Previous Work Very little information has been reported on temperature stability of crosslinked fracturing fluids, especially under shearing conditions. Elbel and Thomas discussed the use of viscosity stabilizers for high-temperature fracturing. Conway et al. subjected crosslinked fracturing fluids to shear and to high temperatures. Hsu and Conway described the development of more stable crosslinked gels for use in deep, hot formations. All these investigators used the Fann 50 viscometer for their work, although Conway et al. used a pump to shear the samples before testing. Flow Loop Description The flow loop was built to evaluate the flow properties of drilling fluids, fracturing fluids, heavy crudes, and waxy crudes. The current test system can operate up to 350F [177C] and 250 psi [1,724 kPa]. The flow loop schematic is shown in Fig. 1. The test fluid is poured into the mixing vessel (Pfaudler) and then flows through the pump. The capacity of the system--including the heat exchangers, the test section, and the mixing unit--is about 25 gal [0.095 m3]. A high-accuracy, oval gear flowmeter was used for flow rate measurement. The meter was used only intermittently because it is a high- shear device that was originally intended to handle oil-base systems. A low-shear magnetic flowmeter has been added to the loop. The magnetic flowmeter shears the test fluids much less than the gear meter and can thus be left on continuously when testing shear-sensitive fracturing fluids. A differential pressure transducer measures pressure drop over the 20-ft-long [6.1-m], 0.957-in.-ID [2.43-cm] test section. The system is heated with a hot oil heater. An in-line, variable-shear-rate cup and bob viscometer allows continuous measurement of apparent viscosity at test temperature and pressure. It also-permits the running of rheograms to measure the flow pressure. It also-permits the running of rheograms to measure the flow parameters of the test fluid at any time during a test. parameters of the test fluid at any time during a test. A remote indication panel provides displays of flow rate, pressure drop, temperatures, shear stress, and shear rate. These values also are recorded on paper and magnetic tapes. A detailed description of the equipment, including recent improvements, is given in the Appendix. The improvements include the magnetic flowmeter mentioned previously, an automated data collection and reduction system, and a smaller pump. SPEJ p. 249

Characterization of the Rheological Behavior of Drilling Fluids

2020 ◽  
Author(s):  
Eric Cayeux ◽  
Amare Leulseged
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Operation Conditions ◽  
Fluid Systems ◽  
Different Temperatures ◽  
The One ◽  
Shear Stress Response

Abstract It is nowadays well accepted that the steady state rheological behavior of drilling fluids must be modelled by at least three parameters. One of the most often used models is the yield power law, also referred as the Herschel-Bulkley model. Other models have been proposed like the one from Robertson-Stiff, while other industries have used other three-parameter models such as the one from Heinz-Casson. Some studies have been made to compare the degree of agreement between different rheological models and rheometer measurements but in most cases, already published works have only used mechanical rheometers that have a limited number of speeds and precision. For this paper, we have taken measurements with a scientific rheometer in well-controlled conditions of temperature and evaporation, and for relevant shear rates that are representative to normally encountered drilling operation conditions. Care has been made to minimize the effect of thixotropy on measurements, as the shear stress response of drilling fluids depends on its shear history. Measurements have been made at different temperatures, for various drilling fluid systems (both water and oil-based), and with variable levels of solid contents. Also, the shear rate reported by the rheometer itself, is corrected to account for the fact that the rheometer estimates the wall shear rate on the assumption that the tested fluid is Newtonian. A measure of proximity between the measurements and a rheological model is defined, thereby allowing the ranking of different rheological behavior model candidates. Based on the 469 rheograms of various drilling fluids that have been analyzed, it appears that the Heinz-Casson model describes most accurately the rheological behavior of the fluid samples, followed by the model of Carreau, Herschel-Bulkley and Robertson-Stiff, in decreasing order of fidelity.

scholarly journals Viscosity Models for Drilling Fluids—Herschel-Bulkley Parameters and Their Use

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5271 ◽  
Author(s):  
Arild Saasen ◽  
Jan David Ytrehus
Keyword(s):  
Shear Rate ◽  
Yield Point ◽  
Drilling Fluid ◽  
Sufficient Accuracy ◽  
Drilling Fluids ◽  
Thermodynamic Quantities ◽  
Shear Rates ◽  
Viscosity Measurements ◽  
Viscosity Models ◽  
Mineralogical Compositions

An evaluation is presented of the practical usage of the Herschel-Bulkley viscosity model for drilling fluids. If data from automatic viscosity measurements exist, the parameters should be selected from relevant shear rate ranges to be applicable. To be able to be used properly, viscosity measurements must be measured with a sufficient accuracy. It is shown that a manual reading of standard viscometers may yield insufficient accuracy. It is also shown that the use of yield point/plastic viscosity (YP/PV) as measured using API or ISO standards normally provide inaccurate viscosity parameters. The use of the Herschel-Bulkley model using dimensionless shear rates is more suitable than the traditional way of writing this model when the scope is to compare different drilling fluids. This approach makes it also easier to make correlations with thermodynamic quantities like pressure and temperature or chemical or mineralogical compositions of the drilling fluid.

Effect of Nanoparticle Shape on Viscoelastic Surfactant Performance at High Temperatures

SPE Journal ◽  
2020 ◽  
pp. 1-19 ◽  
Author(s):  
Ahmed Hanafy ◽  
Faisal Najem ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
High Temperature ◽  
Carrying Capacity ◽  
Spherical Particles ◽  
Formation Damage ◽  
Fluid Loss ◽  
Stability Range ◽  
Fracturing Fluids ◽  
High Pressure High Temperature

Summary Viscoelastic surfactants (VESs) have been used for acid diversion and fracturing fluids. VESs were introduced because they are less damaging than polymers. VESs’ high cost, low thermal stability, and incompatibility with several additives (e.g., corrosion inhibitors) limit their use. The goal of this study is to investigate the interaction of VES micelles with different nanoparticle shapes to reduce VES loadings and enhance their thermal stability. This work examined spherical and rod-shaped nanoparticles of silica and iron oxides. The effects of particle size, shape, and surface charge on a zwitterionic VES micellization were conducted. The physical properties were measured using zeta-potential, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The rheological performances of VES solutions were evaluated at 280 and 350°F using a high-pressure/high-temperature rotational rheometer. The proppant-carrying capacity of the fracturing fluids was evaluated using a high-pressure/high-temperature see-through cell and dynamic oscillatory viscometer. The fluid loss and formation damage were determined using corefloods and computed-tomography scans. The interaction between nanoparticles and VES is strongly dependent on the VES concentration, temperature, nanoparticle characteristics, and concentration. The spherical particles at 7-lbm/1,000 gal loading extended the VES-based-fluid thermal stability at VES loading of 4 wt% up to 350°F. The nanorods effectively enhanced and extended the thermal-stability range of the VES system at VES concentration of only 2 wt%. Both particle shapes performed similarly at 4 wt% VES and 280°F. The addition of silica nanorods extended the thermal stability of the 4 wt% VES aqueous fluid, which resulted in an apparent viscosity of 200 cp for 2 hours. The addition of rod-shaped particles enhanced the micelle to micelle entanglement, especially at VES loading of 2 wt%. The use of nanoparticles enhanced the micelle/micelle networking, boosting the fluid-storage modulus and enhancing the proppant-carrying capacity. The addition of nanoparticles to the VES lowered its fluid-loss rate and minimized formation damage caused by VES-fluid invasion. This research gives guidelines to synthesize nanoparticles to accommodate the chemistry of surfactants for higher-temperature applications. It highlights the importance of the selected nanoparticles on the rheological performance of VES.

Application of modified starch in high-temperature-resistant colloidal gas aphron (CGA) drilling fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenxi Zhu ◽  
Xiuhua Zheng
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Performance ◽  
Oil And Gas ◽  
Elevated Temperatures ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Modified Starch ◽  
Gas Reservoirs ◽  
Building Capability

Abstract Colloidal gas aphrons (CGA) are finding increasing application in depleted oil and gas reservoirs because of their distinctive characteristics. To overcome the limitations of its application in high-temperature drilling, a modified starch foams stabilizer WST with a temperature resistance of 160 °C was synthesized via radical polymerization. The chemical structure of WST was characterized by Fourier infrared spectroscopy and results showed that all three monomers acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid, and N-vinylpyrrolidone have been grafted onto starch efficiently. Based on the microscopic observations, highly stable aphrons have been successfully generated in the WST-based CGA drilling fluids within 160 °C, and most aphrons lie in the range of 10–150 μm. WST can provide higher viscosity at high temperatures compared to xanthan gum, which helps to extend foam life and stability by enhancing the film strength and slowing down the gravity drainage. Results show that WST-CGA aged at elevated temperatures (120–160 °C) is a high-performance drilling fluid with excellent shear-thinning behavior, cutting carrying capacity, and filtration control ability. The significant improvement of filtration control and well-building capability at high temperatures is an important advantage of WST-CGA, which can be attributed to the enhancement of mud cake quality by WST.

A New Technique to Determine the Equivalent Viscosity of Drilling Fluids Under High Temperatures and Pressures

1970 ◽  
Vol 10 (01) ◽  
pp. 33-40 ◽  
Author(s):  
B.K. Sinha
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Relative Viscosity ◽  
Test Fluid ◽  
Drilling Fluids ◽  
Sample Container ◽  
Invert Emulsion ◽  
Temperature And Pressure ◽  
Water Base ◽  
Time Required

Abstract Knowledge concerning the behavior of drilling fluids under wellbore conditions is very desirable, and experimental results have shown that the extent to which the flow properties of drilling fluids are affected by high temperatures and pressures cannot be predicted by standard API pressures cannot be predicted by standard API tests. A Fann consistometer (Model 5S-TDL) is modified to obtain the experimental data reported in this study. Data obtained from the Fann viscometer Model 50 at elevated temperatures have been included to supplement the information derived from the modified Fann consistometer. Newtonian fluids of known viscosities are used in calibrating the modified consistometer. The technique followed here keeps the sample temperature constant and allows the pressure to vary at each desired temperature level. The equivalent viscosities of both laboratory-prepared and field muds of different densities have been obtained at temperatures up to 500 deg F and pressures up to 20,000 psi. The objective of this study is to show that the modified consistometer can give much more information concerning the flow behavior of muds under wellbore conditions than that derived in the past. It can show the pressure and temperature conditions under which the tendency to thicken begins, the gradual thickening, and also the conditions at which the mud completely gels and loses its fluidity. The study shows that both temperature and pressure affect the equivalent viscosity of invert pressure affect the equivalent viscosity of invert emulsion muds. The effect of pressure is very pronounced at low temperatures. Compared to the pronounced at low temperatures. Compared to the invert emulsion muds, the equivalent viscosity of water base muds is not affected to the same extent by temperature and pressure. Temperature is the dominating variable tin case of water base muds. However, the effect of pressure on the equivalent viscosity of water base muds seems to depend on composition and temperature of the system. Introduction Kennedy and Crawford designed and patented the consistometer to test the setting time of cement slurries. This consistometer as manufactured and later improved by Fann. Chisholm et al. adapted the first Fann consistometer for evaluating drilling fluids under wellbore conditions in 1961; their study was later continued by Cox and Pfleger. Weintritt and Hughes used a similar consistometer with a different recording device. They measured the relative viscosity of drilling fluids in seconds and pointed out the usefulness of this data when used with viscometric and fluid loss data. They applied the term "relative viscosity" to the time required for the bob to complete movement in one direction: it is not a ratio of two viscosities. In spite of its wide usage, no standard testing procedure has been established by the industry to procedure has been established by the industry to obtain correlative data. A consistometer similar to the ones mentioned above, has been further modified and used in this study along the Fann viscometer Model 50. EQUIPMENT AND CALIBRATION Fig.1 is a section diagram of the consistometer. The consistency or equivalent viscosity of a test fluid is measured by electrically timing the movement of a soft iron bob that is magnetically pulled up and down in the sample container. Sound pulled up and down in the sample container. Sound signals created by the impingement of the bob inside the container are picked up by a microphone and transmitted to a recorder. The time required to pull the bob through a test fluid is a function of its pull the bob through a test fluid is a function of its consistency. The test fluid can be subjected to pressures up to 20,000 psi and temperatures up pressures up to 20,000 psi and temperatures up to 500 deg F. SPEJ p. 33

scholarly journals Study on the Rheological Properties of Ultra-High Temperature CGA Drilling Fluids

2021 ◽  
Author(s):  
Wenxi Zhu ◽  
Xiuhua Zheng
Keyword(s):  
High Temperature ◽  
Rheological Properties ◽  
High Temperatures ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Underbalanced Drilling ◽  
Deep Wells ◽  
Colloidal Gas Aphron ◽  
Oil Gas ◽  
Ultra High Temperature

Colloidal gas aphron (CGA) drilling fluids are a kind of environmentally-friendly underbalanced drilling technique, which has attracted more attention in depleted reservoirs and other low-pressure areas. With the shortage of global oil/gas resources, drilling has gradually shifted to high-temperature and deep wells. Hence, a study on the ultra-high temperature rheology properties of CGA fluids is lacking and urgently needed. In this study, a novel CGA drilling fluid system was prepared by modified starch and amino acid surfactant, and rheological properties after 120-300°C aged was investigate. Results show that: (1) Herschel-Bulkley model is the preferred model to predict CGA drilling fluid at ultra-high temperatures; (2) It was proved that CGA drilling fluid is a high-quality drilling fluid with extremely high value of LSRV and shear thinning property within 280°C. Compared to the traditional XG-based CGA drilling fluid, the improvement of LSRV at ultra-high temperatures is a significant advantage of EST-based CGA drilling fluid which is conducive to carrying cuttings and sealing formation pores.

Modelling of Drilling Fluid Thixotropy

2018 ◽  
Author(s):  
Eric Cayeux ◽  
Amare Leulseged
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Time Dependence ◽  
Rheological Properties ◽  
Drilling Fluid ◽  
Time Dependent ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Pump Flow Rate ◽  
Drilling Operations

Drilling fluids are visco-elastic materials, i.e. they behave as a viscous fluid when subject to a sufficient shear stress and like an elastic solid otherwise. Both their elastic and viscous properties are time-dependent, i.e. drilling fluids are thixotropic. Because of thixotropy, it takes a finite time before the effective viscosity of a drilling fluid attains an equilibrium when the fluid is subject to a change of shear rate. This effect is visible when one changes the applied shear rate in a rheometer, as the fluid will gradually adapt to the new shearing conditions. When the velocity of a drilling fluid changes, for instance due to a change in pump flow rate, movement of the drill string, or change of flow geometry, the fluid will exhibit a time-dependent response to the new shearing conditions, requiring a certain time to reach the new equilibrium condition. Unfortunately, the time-dependence of the rheological properties of drilling fluids are usually not measured during drilling operations and therefore it is difficult to estimate how thixotropy impacts pressure losses in drilling operations. For that reason, we have systematically measured the time-dependence of the rheological properties of several samples of water-based, oil-based and micronized drilling fluids with a scientific rheometer in order to capture how drilling fluids systems respond to variations of shear rates. Based on these measurements, we propose to investigate how one existing thixotropic model manages to predict the shear stress as a function of the shear rate while accounting for the shear history and gelling conditions. Then we propose a modified model that fits better, overall, with the measurements even though there are still noticeable discrepancies, especially when switching back to low shear rates.

What is More Important for Proppant Transport, Viscosity or Elasticity?

2015 ◽  
Author(s):  
Y. Thomas Hu ◽  
HsinChen Chung ◽  
Maxey Jason
Keyword(s):  
Relaxation Time ◽  
Shear Rate ◽  
Particle Tracking ◽  
Shear Thickening ◽  
Relative Importance ◽  
Local Flow ◽  
Proppant Transport ◽  
Shear Rates ◽  
Hydroxypropyl Guar ◽  
Fracturing Fluids

Abstract The contributions of viscosity and elasticity to inhibiting proppant settling in gelled fracturing fluids are quantified and decoupled in this study. The settling velocity of a single particle under orthogonal shear flow was measured in a transparent Couette flow cell using automatic particle tracking, and the local flow field was mapped using particle tracking velocimetry. The settling behavior is correlated with the rheological properties of the fluids. In carboxymethyl hydroxypropyl guar (CMHPG) crosslinked with borate, particle settling slows as the orthogonal shear rate increases, with settling essentially stopping at sufficiently high shear rates. The authors propose that there are two primary mechanisms for the enhanced particle suspending under the orthogonal shear—shear thickening and elastic lifting. The relative importance of the two factors depends on the shear rate and fluid relaxation time. Specifically, the ratio of the elastic and viscous contribution to particle suspension is γe/v=0.5cλN1(γ˙)η(γ˙), where c is a constant, λ is the stress relaxation time, N1(γ˙)) is the first normal stress difference that depends on the shear rate γ˙, and η(η(γ˙)) is the viscosity. For the crosslinked CMHPG gel examined in this work, it is determined that γe/v=0.26γ˙2, indicating that the viscosity is more important at γ⋅<2s−1, whereas the elasticity becomes dominant at γ˙<2 s−1 for proppant suspending. For the uncrosslinked CMHPG, γe/v=0.0035γ˙1.3 , indicating that the elastic contribution becomes more important than the viscous contribution only at shear rates > 80 s−1. The understanding of the relative importance of viscosity and elasticity can provide guidance for chemists to develop better fracturing fluids and for engineers to model proppant transport

scholarly journals Annular Frictional Pressure Losses for Drilling Fluids

2020 ◽  
Author(s):  
Arild Saasen ◽  
Jan David Ytrehus ◽  
Bjørnar Lund
Keyword(s):  
Shear Rate ◽  
Axial Flow ◽  
Drilling Fluids ◽  
Viscosity Data ◽  
Pressure Losses ◽  
Shear Rates ◽  
Taylor Vortices ◽  
Viscosity Models ◽  
Shear Yield ◽  
Loss Modelling

Abstract The most common viscosity models used in the drilling industry are the Bingham, the Power-Law and the Herschel-Bulkley models. In addition, it is common to refer to the low-shear yield-point. The scope of the present paper is to discuss numerical methods applicable for calculating annular frictional pressure losses. The topic of annular frictional pressure loss modelling has been treated in textbooks. None of these couple their models with the selection of viscosity data from measurements at the relevant shear rates. It is earlier shown how rotation of the inner string in an annulus can complicate the flow due to establishment of Taylor vortices. There are currently no analytical methods to handle such flow. The effect of the vortices depends strongly on the fluid’s composition in addition to the flow conditions. The practical way to handle these situations are by “fingerprinting” during circulation. In the paper examples will be presented showing how the Herschel-Bulkley fluid can be transferred to simple models for axial flow in an annulus where the inner cylinder does not rotate. It is common to use the narrow slot approximation. This method was used by Founargiotakis et al. In this paper both the modified Herschel-Bulkley model with dimensionless shear rates and the traditional model where the consistency depends on the shear rate will be presented. The dimensionless shear rate model can easily be translated back to the traditional form and vice-versa. Mathematical models will be presented. Hence a framework is given that is easier to use for digitalization and automation and in correlations including pressure, temperature and composition.

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