bluuebunny/crossref_metadata_2025_split huggingface dataset:
Testing of a Fluid-Powered Turbo-Acoustic Source for Formation-Damage Remediation
Authors: Kolle J. J. , Theimer A. R. 
Published: February 2010

Abstract
Acoustic energy has the potential to stimulate wells by removing drilling and production damage from the formation near the wellbore, overcoming water block and breaking emulsions. All of these applications require high acoustic power and frequency. A fluid-powered turbo-acoustic source has been developed for operation on coiled tubing. This source generates a high-power, high-frequency resonant acoustic signal in the treatment fluid to ensure good acoustic coupling to the formation. The turbo-acoustic source incorporates a turbine, flow-splitter and resonant cavity to convert hydraulic power into an acoustic signal. A 1-11/16″ prototype generates 2 to 12 kW of acoustic power at 4 kHz. The source was used to recover permeability of sandstone that was damaged with guar gum in laboratory tests. Successful recovery of core permeability requires high-acoustic power levels and underbalanced flow conditions to flush the fines out. The turbo-acoustic source provides the ability to restore near-wellbore permeability using coiled tubing in a variety of well configurations. The tool can be operated with a gas separator for underbalanced operations in depleted wells.
Productivity Impairment of Openhole Gravel Packs Caused by Drilling-Fluid Filtercake
Authors: Hodge R. , Burton R. , Fischer C. , Constien V. 
Published: February 2010

Abstract
One of the many benefits of installing open-hole completions in high angle or horizontal wells is higher well productivity compared to cased and perforated completions. This is particularly true in applications requiring down-hole sand retention. However, earlier studies have shown that productivity of open-hole completions can be impaired by drilling fluid filtercake or filtercake residue. Unfortunately, to obtain a complete gravel pack in an open-hole section, it is necessary to leave the filtercake intact. Once the gravel is placed, this filtercake becomes trapped between the borehole wall and the gravel pack. The final disposition of this filtercake layer has been the source of much speculation over the past 10 - 15 years. Many proponents of open-hole gravel packing contend the filtercake ultimately disperses into discrete components and passes through the gravel pack and screen without impairing productivity. Others suggest that the filtercake is more tenacious and is breached in random, limited locations along the length of the completion leaving the majority of the filtercake intact. If the filtercake is not effectively removed and inflow area is significantly reduced, areas of concentrated flow commonly referred to as "hot-spots" can be created leading to impaired productivity and/or completion failure.
This paper presents a laboratory investigation of open-hole gravel pack impairment from drilling fluid filtercake conducted under simulated down-hole conditions. A limited number of commonly-used Drill-in Fluid (DIF) formulations were selected for this study along with unconsolidated, formation sand samples obtained from whole core. Gravel sizes used in the study were based on the median grain size of the formation sand and ranged from conservatively sized (D50/d50 ~ 2.0) to aggressively sized (D50/d50 &gt; 8). Results of the tests show the extent of filtercake damage to both the formation sand and the gravel pack as well as the depth of permeability reduction. Finally, the benefit of placing a remedial treatment in the open-hole section following the gravel pack is discussed.
Formation Damage and Impact on Gas Flow Caused by Biofilms Growing Within Proppant Packing Used in Hydraulic Fracturing
Authors: Bottero S. , Picioreanu C. , Enzien M. , van Loosdrecht M. C. , Bruining H. , Heimovaara T. 
Published: February 2010

Abstract
Formation damage as a result of hydraulic fracturing of unconventional gas reservoirs is known to occur by many speculated processes such as: filter cakes on fracture faces, matrix swelling, cleat plugging, gel damage and water blocking. In low permeability matrices, capillary forces can also prevent effective dewatering and result in water blocking of gas flow. Another type of formation damage that may be qualitatively understood but not quantified is the impact of biofilms. This paper combines two micro-scale modeling techniques to evaluate and predict the effects of biofilms on proppant packed fractures in unconventional gas reservoirs. Both a two phase flow model for gas and liquid and a modern cellular automaton biofilm model were combined to simulate the impact on gas flow rates in biofouled propped fractures. Initial simulations of just two phase flow without biofilms but varied proppant surface wettabilities, indicated that hydrophobic proppant surfaces provide better dewatering than hydrophilic surfaces. Gas flow rates dropped in half when biofilms were added to the model at a pore volume of approximately 10%. In addition, further modeling indicated even the same biofilm volume but different distribution within grains and pore-throats can impact gas flow rates as much as 10%. It is hoped that this work will help hydraulic fracturing engineers improve their fracture designs and subsequent treatments to maximize gas flow rates from their assets.
A Flow Simulator for the Design of Extreme-Length Gravel Packs Utilizing Alternate-Path Technology
Authors: Rao B. N. , Amin A. M. 
Published: February 2010

Abstract
A transient flow simulator has been developed for the design of extreme length (5000 ft or longer), horizontal gravel pack operations. The flow simulator incorporates alternate path technology concepts which include shunt tube hydraulics to bypass bridges/barriers in the well/screen annulus.
Alternate path technology has been successfully utilized for sand control in deep water wells and, over the past decade, this technology has been applied in gravel pack intervals up to about 3000 ft. Very recent works (Barry et al. 2007; Yeh et al. 2008) have reviewed the development of alternate path technology and presented the mechanics of slurry diversion in a revised design of the multiple-shunt manifold system for extending gravel pack operations to extreme lengths of 5000 ft or greater.
In this paper, the revised design of the multiple-shunt manifold system (Barry et al. 2007; Yeh et al. 2008) is incorporated in the development of the transient gravel pack flow simulator. The shunt tube hydraulics for various slurry front locations in the well/screen annulus during gravel packing is depicted in example simulations. Results from the simulations are discussed from both steady-state and transient view points. Steady-state results include the variation of pressure and shunt tube flow rates with measured depth. Transient results are presented as variations of pump pressure, crossover tool pressure, and slurry front location with elapsed time. These simulations provide some insight into the shunt tube hydraulics and associated packing mechanism as well as key pressures during gravel packing.
The flow simulator can be utilized to plan and design horizontal gravel pack operations in extremely long intervals in combination with emerging technologies such as openhole gravel packing with zonal isolation or selectively gravel packing targeted intervals using alternate path technology.
Influence of Acid-Fracture Fluid Properties on Acid-Etched Surfaces and Resulting Fracture Conductivity
Authors: Pournik M. , Gomaa A. , Nasr-El-Din H. A. 
Published: February 2010

Abstract
While experimental studies have shown acid type significantly influences resulting fracture conductivity, there has been limited work on how fluid properties relate to etched fracture faces and hence the resulting conductivity. The effects of acid solutions injected into hydraulic fractures created in carbonate formations can be assessed at the laboratory scale in acid fracture conductivity tests that mimic the conditions in an actual acid fracture treatment.
Many different acid systems are currently applied in acid fracturing treatments with various degrees of success. However, there is no clear understanding of the mechanisms that lead to success of a treatment. It is clear that acid properties influence and shape the success of an acid fracturing treatment. In order to develop a better methodology for design of acid fracturing treatments, the effect of acid fluid properties on the resulting conductivity and etching must be determined. A series of acid fracture conductivity tests was conducted using four commonly used acid fracturing fluids—gelled, in-situ gelled, emulsified, surfactant-based acid. Detailed rheological properties were measured in order to explain trends noted with conductivity data.
Acid system influences the degree of etching and the etching pattern due to differences in chemical and physical properties of acid systems. Under our experimental conditions, viscoelastic acid generated the greatest degree of etching and best etching pattern. Majority of experiments showed differences in conductivity among acid systems tested with most optimal acid system depending on the closure stress. While viscoelastic acid generated the highest conductivity at low closure stress, emulsified acid resulted in the largest retained conductivity at higher loads for our experimental conditions. Furthermore, effluent analysis on both the leakoff and fracture flow showed that most of the fracture face etching is the result of leaked acid into the formation with minimal etching from the fracture flow acid.
Modelling Well Inflow Potential in Three Dimensions Using Computational Fluid Dynamics
Authors: Byrne M. T. , Jimenez M. A. , Rojas E. A. , Chavez J. C. 
Published: February 2010

Abstract
Conventional well inflow modeling fails to capture the complexity of flow in to wells from asymmetric near wellbore permeability distribution. In order to simulate flow in to horizontal wells with varying degrees of damage along the well and around the circumference a complex numerical model is required. Computational fluid dynamics enables fluid flow in to the well to be modeled.
Along a horizontal well the magnitude and depth of mud cake, filtrate invasion and formation damage will vary. Longer exposure times at the heel of a well and lower drawdown at the toe will lead to different formation damage, clean-up and inflow patterns along the well. In addition, gravity can have a profound effect on damage distribution at the base, middle and top of the well. Thicker mud cakes will tend to develop at the base of the well and whilst there may be more erosion on the low side, this will only serve to compound the damage by leading to deeper mud invasion. Inevitably, formation damage will have an asymmetric distribution along and around the well. Asymmetric models of fluid flow in to horizontal wells have been created to reflect the damage heterogeneity.
Results of the models have shown that even in homogenous reservoirs, the vast majority of inflow in to the well is derived from the high side of the heel of the well. Modeling shows the potential impact of consistent chemical clean-up and of inflow control along the horizontal well. By fully capturing the magnitude and impact of damage in conventional wells using computational fluid dynamics, the value of well drilling and completion options such as underbalance drilling and hydraulic fracturing can be evaluated.
This paper presents the first use of complex three dimensional computational fluid dynamic models to predict and mitigate against asymmetric formation damage in horizontal wells.
Impact of Organic Acids/Chelating Agents on the Rheological Properties of an Amidoamine Oxide Surfactant
Authors: Li L. , Nasr-El-Din H. A. , Crews J. B. , Cawiezel K. E. 
Published: February 2010

Abstract
Surfactant-based acids have been used for acid diversion because they are less damaging to the formation. Amphoteric viscoelastic surfactant is the main type of surfactants being used today. Low viscosity is observed in the live acid systems, whereas significantly increased viscosity is found when HCl reacts with carbonate and generates divalent salts. The surfactant-acid system can be broken after acid treatments by mixing with reservoir hydrocarbons, or by using an external or internal breaker.
Amidoamine oxide, an amphoteric surfactant, was examined in this work. The prepared surfactant-based live acid system contained 20 wt% HCl, 4 wt% surfactant and 1 wt% corrosion inhibitor. Different organic acids/chelating agents were added to live and spent acids. Calcium carbonate particles were used to neutralize live acids. The objective was to examine how these organic acids/chelating agents affected the rheological properties of spent acid systems. Measurements were made at temperatures from 75 to 200 °F, at a shear rate of 10 s-1 at 300 psi. Several simple organic acids (formic acid, acetic acid, propionic acid, and butyric acid), chelating agents (glycolic acid, lactic acid, gluconic acid, citric acid, tetrasodium EDTA, tetrasodium GLDA and disodium HEIDA) that are used in the field were examined.
Experimental results indicated that the addition of organic acid/chelating agents significantly reduced the viscosity of spent acids. This reduction in viscosity increased with the number of carbon atoms in the acid. The addition of organic acids reduced the temperature range where the surfactant can be used. Chelating agents (α-hydroxyl carboxylic acids and amino acids) also tended to break the surfactant gel if enough acid was used. Based on the results obtained, organic acids can be used to break surfactant gel. TEM tests were first conducted to examine how organic acids/chelating agents interfered with the formation of rod-like micelles in the surfactant-based acid. The results showed that the addition of organic acids to the spent acid generated less elongated micelle structures and resulted in less apparent viscosity. In addition, if chelating agents or simple organic acids are used, then the concentration of the surfactant should be increased to compensate for the loss of viscosity induced by the addition of the organic acids.
New Filtration-Control Polymer for Improved Brine-Based Reservoir Drilling-Fluids Performance at Temperatures in Excess of 400°F and High Pressure
Authors: Ezell R. G. , Ezzat A. M. , Turner J. K. , Wu J. J. 
Published: February 2010

Abstract
Brine-based reservoir drilling fluids are a special class of fluids designed to minimize formation damage, provide the necessary hole cleaning, help reduce wellbore cleanup time and cost, and allow reservoirs to be produced to the maximum of their potential. These fluids should address the wide range of difficulties frequently encountered in horizontal drilling, completion, and workover operations. Filtration control chemicals for currently available drill-in fluid systems exposed to extremely high bottomhole temperatures and pressure conditions are not effective or stable for drilling long horizontal sections of the reservoir. Failure to secure a low filtration rate and thin wallcake causes stuck pipe and loss of expensive downhole tools.
Conventional fluid loss control additives for high performance brine-based drill-in fluids include nonionic water soluble polymers, such as starches, derivatized starches, gums, derivatized gums, and cellulosics. Cross-linked starches are often considered the benchmark of performance for utilization in reservoir fluids, but they do not have the thermal stability required for successful deployment at temperatures exceeding 300°F for extended contact periods.
Conventional linear synthetic polymers are also utilized, but oftentimes they require another additive, such as phyllosilicate particles, to be able to effectively function as fluid loss control additives. The use of clay can be problematic in drill-in fluids, as removing the clay from the formation can be difficult because it infiltrates into pores. Furthermore, the addition of the linear synthetic polymers dramatically increases the viscosity of the fluid, which can result in increased equivalent circulating densities (ECD) and decreased drilling rates.
Through advanced synthetic polymer techniques, a novel polymeric fluid loss control additive has been developed for brine-based reservoir drill-in and completion fluids. The new polymer provides enhanced thermal stability to temperature in excess of 400°F in monovalent and divalent halide brines. This paper presents detailed fluid formulations and discusses the polymer evaluation data under simulated downhole HPHT conditions.
Quantitative Theory for Fines Migration and Formation Damage
Authors: Bedrikovetsky P. , Siqueira F. D. , Furtado C. , de Souza A. L. 
Published: February 2010

Abstract
Particle detachment from the matrix during suspension transport in porous media was widely observed for laboratory corefloods and flows in natural reservoirs. A new mathematical model for detachment of particles is based on mechanical equilibrium of a particle positioned on the internal cake in the pore space. The torque balance of drag, electrostatic, lifting and gravity forces, acting on the particle from the matrix and the moving fluid, is considered. The torque balance determines maximum retention concentration during particle capture. The particle torque equilibrium is determined by dimensionless ratio between the drag and normal forces acting on the particle on cake surface. The maximum retention function of the dislodging number closes system of governing equations for colloid transport with particle release.
One-dimensional problem of coreflooding by suspension accounting for particle release allows for exact solution under the assumptions of constant filtration coefficient and porosity. The explicit formulae permit the calculation of the model parameters (maximum retention concentration, filtration and formation damage coefficients) from the history of the pressure drop across the core during suspension injection. The values for maximum retention concentration, as obtained from two coreflood tests, have been matched by torque balance on the micro scale.
Antihemolytic and antioxidant activities of Allium paradoxum
Authors: Ebrahimzadeh Mohammad , Nabavi Seyed , Nabavi Seyed , Eslami Bahman 
Published: February 2010

AbstractAntioxidant activity of the aerial part and bulbs of Allium paradoxum was investigated by eight in vitro assay systems. Extracts showed good antioxidant activity. IC50 for 1,1-diphenyl-2-picryl hydrazyl radical-scavenging activity was 890.9±43.2 and 984.9±33.5 µg/ml for the aerial part and bulbs, respectively. The aerial parts have better reducing power than bulb extracts but not comparable with Vitamin C (P>0.001). Extracts showed weak Fe2+ chelating ability, the IC50 being 959±47 and 530±24 µg/ml for bulbs and aerial parts, respectively. Both tested extracts exhibited good hydrogen peroxide scavenging in a concentration dependent manner. They exhibited good antioxidant activity against the hemoglobin-induced linoleic acid system that was comparable with vitamin C (P>0.01). They showed good activity against cumene hydro peroxide induced hemolysis in RBCs. In addition, they possessed antihemolytic activity. The extract from aerial parts had significantly higher total phenol and flavonoid content than did bulbs. Amounts of eight elements (Cu, Mn, Zn, Fe, Ni, Pb, Cd and Cr) were also determined in the bulb and aerial part using atomic absorption spectroscopy. They contained higher Fe and Mn contents than other elements.
Magnetic resonance imaging of ligaments and membranes in the craniocervical junction in whiplash-associated injury and in healthy control subjects
Authors: Dullerud Reidar , Gjertsen Øivind , Server Andrés 
Published: February 2010

Background: The pathogenesis and imaging findings in whiplash-associated injury (WAD) are poorly understood and remain debatable. Purpose: To assess the ligaments and membranes in the craniocervical junction with magnetic resonance imaging (MRI) in patients with WAD and to compare them with healthy control subjects. Material and Methods: Twenty-eight patients with WAD were selected at random from a total number of 180 examined with MRI using 2-mm proton density (PD)-weighted images in three orthogonal planes at 1.5T. The patients were compared with 27 healthy control subjects without neck trauma. Results: High signal intensity of the alar and transverse ligaments was quite common and was reported at an average of about 50% both among patients and control subjects. The incidence of abnormalities of the tectorial and posterior atlantooccipital membranes was low in both groups. No statistically significant difference between control subjects and patients with WAD was revealed for any of the structures assessed. Additional fat-suppressed images seemed to reduce the number of reported anomalies. Conclusion: Due to lack of significant differences between patients with WAD and healthy control subjects, it is not recommended that MRI with the current technique and classification system be used in the routine workup of patients with WAD.
Ultrasonography-guided vacuum-assisted biopsy of microcalcifications: Comparison of the diagnostic yield of calcified cores and non-calcified cores on specimen radiographs
Authors: Cho Nariya , Moon Woo Kyung , Chang Jung Min , Park Sang Hee , Lyou Chae Yeon , Park In Ae 
Published: February 2010

Background: Microcalcifications found on mammography of asymptomatic women can be sampled by ultrasound (US)-guided percutaneous breast biopsy when stereotactic core biopsy is unavailable or unsuccessful. The role of specimen radiograph needs to be reevaluated after US-guided biopsy. Purpose: To compare retrospectively the histological diagnoses of calcified cores and non-calcified cores as depicted on specimen radiographs after a US-guided, 11-gauge, vacuum-assisted biopsy using surgical histology as the reference standard. Material and Methods: A total of 135 consecutive patients underwent a US-guided vacuum-assisted biopsy for calcifications with malignant histological results from 135 lesions. For each lesion, calcification was identified in at least one core on specimen radiographs. Calcified cores and non-calcified cores depicted on specimen radiographs were separately submitted to the pathology department. The pathological diagnoses of calcified cores and non-calcified cores were compared with final diagnoses at surgical excision. Results: Of a total of 2049 core specimens that were obtained (mean, 15 per lesion; range, 4–35 per lesion), 794 cores (mean, 5.9 per lesion; range, 1–17 per lesion) contained calcifications and 1255 cores (mean, 9.3 cores per lesion; range, 1–34 cores per lesion) did not contain calcifications. Calcified cores were more likely to enable an accurate diagnosis of cancer as compared to non-calcified cores (67%, 91 of 135 versus 52%, 70 of 135; P = 0.009). A diagnosis of cancer was more likely to be missed with non-calcified cores as compared to calcified cores (16%, 21 of 135 versus 4%, 5 of 135; P = 0.002). There was no difference in the underestimation of malignancy between calcified cores (29%, 39 of 135) and non-calcified cores (33%, 44 of 135) ( P = 0.510). Conclusion: Calcified cores depicted on specimen radiographs are more accurate for a diagnosis of cancer as compared to non-calcified cores obtained during US-guided vacuum-assisted biopsy of microcalcifications.