bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitigating Borehole Instability and Formation Damage with Temporary Shielding Drilling Fluids in Low Permeability Fractured Reservoirs
Authors: You Lijun , Kang Yili , Li Xiangchen , Zhou Guangqing 
Published: June 2013

Abstract
Along with the increasingly deep wells and long horizontal wells, the wellbore instability and formation damage undeniably becomes the biggest concerns during well construction. Sha 3 reservoirs in faulted B Depression, a low permeability exploration target zones, are highly fractured. Most of the wells with the barefoot interval length of over 2000m or even about 3500m were drilled under underbalanced conditions to improve exploration success rate. The exploration results were disappointing. Shale sloughing and borehole enlargement frequently occurred during the process of previous drilling, followed by some troubles including serious formation damage. Different kinds of drilling fluid techniques, including the nano-emulsion drilling fluid, polymeric alcohol and potassium formate, were tried to settle these problems with mixed results. Mineral analysis, shale dispersion and swelling test, and dynamic leakoff tests show that the solid particles mismatching well with the sizes of pore throats and the width of natural fractures and the high pH value of drilling fluids are two key factors triggered the borehole instability and formation damage. Based on the temporary shielding theory, the modified drilling fluids are developed by adding fibrous bridging agents and by decreasing pH value. Dynamic leakoff tests manifest that the modified drilling fluids are able to rapidly seal the micro fractures and pore throats and the percentage of regained permeability can reach more than 85%. Two experiment wells, a vertical well and a sidetracked well, located in an area of severe shale sloughing, were drilled with the modified drill fluids under micro overbalanced conditions. The results indict that the diameters of two boreholes are near-gauge, that the coring, well logging and completion operations are conducted very successfully, and that the well construction time is cut down by 50% compared with that of previous drilled wells.
Optimized Filter Cake Breaker Successfully Used in the OH Completions in Yuralpa and Oso Fields
Authors: Torres Camilo , Sinche Galo , Navarro Raul , Endara Edison , Carreón Francisco , Murillo Pablo , Cortez Santiago 
Published: June 2013

Abstract
Oil provides 51% of Ecuador export earnings and a third of government revenue. Horizontal drilling has become an option to increase domestic oil production. The Yuralpa and Oso are land oil producer fields in Ecuador, which includes several wells. Some of the challenges include low pore pressure, sand control and the need of a filter cake breaker to enhance productivity. The reservoir drill-in fluid (RDF) and the breaker needed to be compatible, as well the operator required a breaker formulation that would not only allow the upper completion to be run before losing filtration control but also deliver superb productivity on completion after adequate soak time. It was also important that the solution as well required to be cost effective due to the low AFE that the operator had on the project. A water based breaker system, comprised of enzyme and chelant components, was chosen as the treatment selection. The thin RDF filtercake and the breaker treatment combination were tested in the laboratories to achieve an optimum technical and economical solution for the project. Due to environmental restrictions, sodium formate was used to provide density for drilling the horizontal hole section. After drilling, a mechanical and chemical wellbore clean up were performed, the pre-perforated liner was run, and the filter cake breaker was spotted at the open hole
Potassium chloride brine was used as final completion fluid. Operations continue running in hole the upper completion assembly which some times includes an electric submersible pump (ESP). The usage of the novel breaker system allowed the project to achieve higher production rates than expected. Several wells have been successfully completed and put in production, all achieving or exceeding production expectations.
Properties and Applications of an Alternative Aminopolycarboxylic Acid for Acidizing of Sandstones and Carbonates
Authors: Reyes Enrique A. , Smith Alyssa L. , Beuterbaugh Aaron 
Published: June 2013

Abstract
Significant advances in acidizing chemistry have led to the introduction of sequestering agents, such as hydroxypolycarboxylic acids, followed by chelating agents, to mitigate precipitation reactions. The initiative to obtain fluids with an improved environmental footprint has led to the redesign of treatment fluids to possess distinct advantages, such as stability at higher temperature, broader pH activity, and stronger complex formation. In the area of hydrofluoric (HF) acidizing chemistry, the conceptualization of the unique HF acid reactions on clays and silica surfaces—namely, kinetic controls over the so-called primary, secondary, and tertiary reactions—has facilitated fluid designs that can handle such varied reactions. The work presented here describes the development of a new acidizing fluid containing an environmentally relevant chelating agent and an aminpolyocarboxylic acid.
The chelating agent is fully biodegradable, according to the Organization for Economic Co-operation and Development (OECD) protocols, is stable in fluid media from pH 1 to 7 and at high temperatures, and stabilizes the dissolved ions during an acidizing treatment. In HF acidizing, the chelant performance has been tested at 0.6 mol/L and HF acid concentrations from 0.5 to 2%, pH of 2.5 to 4, including a stabilizing agent to mitigate the precipitation of fluorosilicates or fluoroaluminates, and is effective in temperature ranges from 200 to 300°F. Laboratory tests show it to be effective in maintaining in solution dissolved aluminum (3000 to 10 000 mg/L), calcium (5000 mg/L), and iron (6000 mg/L). The use of nuclear magnetic resonance (NMR) spectroscopic analysis revealed additional dissolved-fluoride-containing species that has not been previously reported. Moreover, the chelating agent can also be used when stimulating carbonate rocks in concentrations from 0.2 to 0.6 M with a pH of 1 to 4 and is effective from 125 to 350°F. The representative pore volume breakthrough (PVbt) curves provide an indication of the distinct reactivity of this chelant.
Impact of Fe (III) on the Performance of VES-Based Acids
Authors: Shu Yi , Wang Guanqun , Nasr-El-Din Hisham A. , Zhou Jian 
Published: June 2013

Abstract
Viscoelastic surfactant (VES)-based acid systems have been used successfully in matrix and acid fracturing treatments. However, the existence of Fe (III) as a contaminant in such systems may lead to many problems, due to interactions between VES and Fe (III). Such interactions could reduce the effectiveness of VES-based acid systems and may lead to formation damage.
In this paper, reaction mechanisms between VES and Fe (III) were studied. Rheological properties of two surfactants were examined with various concentrations of Fe (III). A scanning electron microscope (SEM) was used to identify precipitates from reaction products. Inductively coupled plasma (ICP) was applied to measure iron concentration, and the two-phase titration method was used to determine VES concentration in all phases of the sample. The effect of several chelating agents on the reaction of VES with Fe (III) was also examined.
Experimental results indicate that the apparent viscosity of live VES-based acids (20 wt% HCl, 4 vol% VES) increased from 14 to 751 cp at a shear rate of 10 s-1 when the Fe (III) concentration was increased from 0 to 2,300 ppm, and started to decrease at higher Fe (III) concentrations. This is because of the electrical bonding between negative charged [FeCl4]- groups and positive charged amine groups in VES in live acids. Both surfactants interacted with Fe (III) and precipitates, which are complexes containing iron and VES, were noted at 5,000 ppm and higher concentrations of Fe (III). On the other hand, adding a chelating agent [1:1 mole ratio to Fe (III)] reduced the apparent viscosity of the sample to no more than 40 cp at the shear rate of 10 s-1 when Fe (III) concentration is lower than 4,000 ppm, which means that the chelating agent reacted with Fe (III) and reduced interactions between VES and Fe (III). Adding a suitable chelating agent can minimize the impact of Fe (III) on VES-based acids.
Thermal Decomposition of Chelating Agents and a New Mechanism of Formation Damage
Authors: Sokhanvarian Khatere , Nasr-El-Din Hisham A. , De Wolf Corine A. 
Published: June 2013

Abstract
Chelating agents are used in the oil and gas industry mainly to: remove inorganic scales, control iron during acid treatments, and stimulate carbonate/sandstone reservoirs. The main chelating agents used in the field, include: ethylenediaminetetraacetic acid (EDTA), N-(hydroxyethyl)-ethylenediaminetriaacetic acid (HEDTA), and recently glutamic acid-N, N diacetic acid (GLDA). As with all organic acids, one of the main concerns with using these chelates is their stability at elevated temperatures. Therefore, the objectives of the present study are to: 1) assess thermal stability of various chelates, and 2) examine the effect of thermal degradation products on the permeability of carbonate and sandstone cores.
We prepared solutions (0.4 to 0.6 M) of HEDTA, GLDA, EDTA, and their salts. The solutions of these chelates were heated at various temperatures up to 400°F and times (2 to 12 hrs.). The thermal stability of these chelating agents was determined by measuring the concentration of the chelates before and after heating using a titration method utilizing FeCl3 as a titrant. Mass spectrometry was used to determine the degradation products. We injected GLDA to high permeability Indiana limestone, and investigated the effect of soaking of GLDA at high temperature on the final permeability of the core. Coreflood tests were conducted at 340°F and 5 cm3/min.
Chelating agents degraded at temperatures greater than 350°F. The decomposition products included: iminodiacetic acid, acetic acid, and ⍰-hydroxy acids. The addition of salt and raising pH improved the thermal stability of chelates. Thus, careful design of the chelate-based treatment fluids can prevent loss of functionality at elevated temperatures in the field, enhancing the versatility of these solutions, and minimizing formation damage due to decomposition products.
Effectively Controlling Proppant Flowback to Maximize Well Production: Lessons Learned from Argentina
Authors: Nguyen P. D. , Bonapace J. C. , Kruse G. F. , Solis L. , Daparo D. 
Published: June 2013

Abstract
Flowback of proppant and formation sand often poses serious challenges to operating companies. These solids can cause equipment damage, costly and frequent cleanup treatments, and production decreases. Various mechanisms were found that destabilize the proppant pack, causing the proppant to produce back with the production fluid. Since 2005, curable resin systems for coating proppant on-the-fly during hydraulic fracturing completions and remedial proppant treatments of propped fractures have been applied in Argentina to provide an effective means for proppant flowback control and screenless completions in various basins.
Evaluation of these applications has helped determine that optimum concentrations of resin coatings on the proppant in either primary or remedial treatments are necessary to maximize the bonding between proppant grains to lock the grains in place while minimizing any reduction of the proppant pack conductivity. Additives included in the liquid resin systems permit good consolidation properties in the proppant pack, allowing it to effectively handle the shear forces of high production rates and multiphase flow and the effect of stress cycling as the well undergoes producing and being shut in.
Field results indicate that on-the-fly resin coating on proppant and remedial treatments effectively stops the proppant from producing back while allowing the well production rates to be maximized as designed. These processes have drastically decreased the number of solids cleanout workovers in the treated wells compared to the offset wells in the same field where resin treatments were not performed. These resin treatments provide a reliable and cost-effective alternative in marginal reservoirs, eliminating the need for sand screens and providing access to other intervals when deemed necessary without wellbore restrictions.
A Novel Approach for Predicting In-situ Breakdown Conditions for Wireline Mini-Fracture Testing
Authors: Barnhoorn Auke , Magalhaes Boris Sintra , Subbiah Surej Kumar , Zitha Pacelli 
Published: June 2013

Abstract
Wireline dual-packer mini-fracture testing jobs are used to determine the critical formation breakdown parameters needed for field-scale hydraulic fracture design, water and gas injection management, wellbore stability and sand production. A wireline dual-packer mini-fracture test consists of injection a small volume of fluids at constant flow rate into an open borehole to pressurize the formation and induce fracturing.
The performance of a wireline mini-fracture test and formation failure depends on far-field stress conditions, rock properties (geomechanical properties: elastic properties, strength; microstructural properties: porosity/permeability, pore pressure) as well as operational properties (borehole fluid pressures, flow rates, viscosity). Thus far, wireline mini-fracture tests experienced mixed successes pointing to a need to better predict the expected failure conditions of the formations before application of the wireline dual-packer mini-fracture jobs.
A novel simulator was developed that combines all main parameters (stress conditions, geomechanical & rock properties and operational parameters) controlling the performance of a mini-fracture job and the conditions at which tensile failure should occur near the wellbore. Sensitivity analyses with the simulator showed that rock permeability has the largest influence on the flow rates and fluid-pressure build-up over time. Geomechanical properties as the Young Modulus and Poisson's ratio have a large effect on the fluid pressures needed for tensile failure. Tool specifications determine the maximum fluid pressures that can be reached. The combination of these parameters determines ultimately the possible success or failure of the mini-fracture testing job. The developed simulator can be used to predict the conditions at which tensile failure is expected and can then guide and be compared with actual field tests.
Sand Control in Shallow Unconsolidated Sandstone Oil Reservoirs at Staatsolie N.V. Suriname
Authors: Toelsie S. , Goerdajal P. 
Published: June 2013

Abstract
Hydrocarbon production from unconsolidated sand reservoirs requires sand control usually consisting of the installation of a screen combined with gravelpacking. Several existing criteria such as Tiffin, Saucier and Coberly can be used for optimal selection of the sand control design. Sand and fines production in oil and gas wells are one of the main challenges and can result in failures of production systems. Especially in unconsolidated sand reservoirs, proper sand control practices are required to prevent reservoir sand production. At Staatsolie sizing of sand control design is based on the Saucier method incorporating the results of reservoir sand particle size distribution of side wall core samples.
A Staatsolie-Suriname in-depth research of sand control practices in shallow, low-pressure, heavy-oil unconsolidated sand reservoirs completed with progressive cavity pumps will be presented. The conventional sand control method applied is the installation of formation sand sized wire wrapped screens and gravelpack completion on uniform and non-uniform distributed reservoir sands. Stand alone screen completions have revealed its application in uniform distributed reservoir sands. Sand production and control on depleted and complex reservoirs based on the conventional method has become a major challenge. In Suriname, in three onshore fields approximately 1,500 wells are completed and are in production. With improved sand control practices, failures have been reduced to less than 5 wells per year.
The study has demonstrated the challenges and benefits of sand control in these complex unconsolidated Tertiary reservoirs. This has resulted into increased production and economic benefits. Results of lab tests and field cases will be presented and recommendations will be given on the best approach for sand control practices and the most cost effective sand control solutions in unconsolidated shallow sand reservoirs.
Significant Increase in Sand Control Reliability of Open Hole Gravel Pack Completions in ACG Field - Azerbaijan
Authors: Susilo Yoliandri , Whaley Kevin , Loboguerrero Santiago , Jackson Phillip , Kerimov Natig , Anderson Robert , Keatinge Patrick , Edment Brian 
Published: June 2013

Abstract
Azeri-Chirag-Gunashli (ACG) is a giant field located in the Caspian Sea, Azerbaijan. The major reservoir zones are Pereriv sandstone formations with 20–25% porosity, permeability 100–1000md, and oil column up-to 1000m. These formations are weakly consolidated where Open Hole Gravel Pack (OHGP) completions have become the standard design for production wells. Development began in 1997 and to date more than 70 high rate (up to 45mbd per well) OHGPs have been installed.
Wellbore stability issues require OHGP screens to be run in Oil Base Mud (OBM). Despite excellent initial success a number of sand control failures began to occur in 2008. A detailed gravel pack evaluation using multiple wash pipe gauges have revealed that earlier installations experienced screen plugging on lower section during the installation process. This leads to an incomplete pack in the toe area and subsequent screen failure as depletion increases or once water breakthrough occurs. The ultimate risk is of lost production rather than well control or loss of containment.
Analysis was done to understand the root causes of screen plugging and to develop solutions for each. The work resulted in five key changes being made to the OHGP completions.
○ Revised TD criteria for the open hole section. ○ Modified OBM conditioning procedures. ○ Modified wellbore-clean-out procedures. ○ A modified screen BHA design. ○ The use of Ultra-Fine-Grain Barite in the OBM to reduce barite sag and the amount of large solids in the fluid system.
These changes have resulted in less screen plugging, and hence increasing pack efficiency across the productive interval. This has resulted in a step change in OHGP reliability in the last 3 years with zero sand control failures over the last 24 completions. The detailed understanding of the failure mechanism also facilitated a successful intervention campaign to remediate several failed OHGP wells pre 2008. These efforts have delivered ~60mbd reduction in production losses over the past 2 years.
Characterization of Renal Glucose Reabsorption in Response to Dapagliflozin in Healthy Subjects and Subjects With Type 2 Diabetes
Authors: DeFronzo Ralph A. , Hompesch Marcus , Kasichayanula Sreeneeranj , Liu Xiaoni , Hong Ying , Pfister Marc , Morrow Linda A. , Leslie Bruce R. , Boulton David W. , Ching Agatha , LaCreta Frank P. , Griffen Steven C. 
Published: June 2013

OBJECTIVE
To examine the effect of dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, on the major components of renal glucose reabsorption (decreased maximum renal glucose reabsorptive capacity [TmG], increased splay, and reduced threshold), using the pancreatic/stepped hyperglycemic clamp (SHC) technique.

RESEARCH DESIGN AND METHODS
Subjects with type 2 diabetes (n = 12) and matched healthy subjects (n = 12) underwent pancreatic/SHC (plasma glucose range 5.5–30.5 mmol/L) at baseline and after 7 days of dapagliflozin treatment. A pharmacodynamic model was developed to describe the major components of renal glucose reabsorption for both groups and then used to estimate these parameters from individual glucose titration curves.

RESULTS
At baseline, type 2 diabetic subjects had elevated TmG, splay, and threshold compared with controls. Dapagliflozin treatment reduced the TmG and splay in both groups. However, the most significant effect of dapagliflozin was a reduction of the renal threshold for glucose excretion in type 2 diabetic and control subjects.

CONCLUSIONS
The SGLT2 inhibitor dapagliflozin improves glycemic control in diabetic patients by reducing the TmG and threshold at which glucose is excreted in the urine.
Effect of Ti, Nb, Cr and B on Structure and Mechanical Properties of High Aluminium Cast Iron
Authors: Kopyciński D. 
Published: June 2013

Abstract
In this work, a method was investigated to eliminate the presence of undesirable Al4C3 phases in a high-aluminium alloys, and thus improve the production process. The melting conditions employed in this work enabled the formation of a Fe-Al-C liquid solution. Moreover, titanium additions into the liquid allowed the precipitation of TiC. According to this reaction, the extent of carbon removal from the melt is strongly influenced by the amount of Ti additions. Hence, proper titanium levels can result in total removal of carbon from the liquid. Notice from this figure that Ti additions above 4.5%, totally eliminate the undesirable Al4C3 precipitates. Making Cr, Ti, B additions reduces size of FeAl alloys grains. In addition, this work indicates that the high-aluminium cast iron posses high oxidation resistance, exceeding that of high-chromium cast iron and chromium cast steels. Finally, the alloy ductility can be enhanced by additions of dopants such as B and Cr. Hence, additions of 0.03% B and 0.03%B-5% Cr combined with a heat treatment were implemented. As a result, the alloy ductility was significantly improved, where the strain of up to 5.3%, (B alone) or 15% (B-Cr) were obtained.
The relation between GxE interaction and the number of locations in series of oilseed rape trials
Authors: Pilarczyk Wiesław 
Published: June 2013

SUMMARYThe problem of the selection of locations (experimental stations) for experiments on oilseed rape is considered. The results of 138 experiments conducted by the Research Centre for Cultivar Testing (COBORU) in the period 2006-2010 at 41 experimental stations form the basis for all considerations. The method applied earlier by Pilarczyk and Fraś (2007, 2010) for analysis of similar results concerning winter wheat was utilized here. However, because of the high degree of non-orthogonality of the data (slightly overlapping sets of varieties among years) only analyses of single-year series were possible. The locations with a high contribution to the genotype-environment interaction were identified.
Numerical Analysis for Two-phase Flow in Porous Media
Authors: Chen Zhangxin 
Published: June 2013

Abstract In this paper we derive error estimates for finite element approximations for partial differential systems
which describe two-phase immiscible flows in porous media. These approximations are based on mixed finite element
methods for pressure and velocity and characteristic finite element methods for saturation. Both incompressible and
compressible flows are considered. Error estimates of optimal order are obtained.
Error Bounds for Finite Element Methods with Generalized Cubic Splines for a 4-th Order Ordinary Differential Equation with Nonsmooth Data
Authors: Zlotnik A. , Kireeva O. 
Published: June 2013

Abstract A boundary value problem for a 4-th order self-adjoint ordinary differential
equation is considered in the case where the coefficients of the equation and its
right-hand side can be nonsmooth (discontinuous, concentrated or rapidly oscillating
functions). Generalized cubic splines of deficiency 1 depending on the major coefficient
of the equation are applied. An error analysis of finite element methods exploiting such
splines is presented in detail including superconvergence error bounds. .