bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Aqueous-Based Consolidation Restores Sand Control and Well Productivity: Case History from East Malaysia
Authors: Riyanto Latief , Saleh Malaz , Goh Kellen , Ambrose Jonathan , Kristanto Tutus , Hong Chua Yek 
Published: January 2016

Abstract
The integrity of sand control method is often compromised as wells get older and the field becomes more mature. An operator in East Malaysia pursued a cost-effective alternative remedial sand-control solution to restore the functionality of its sand control completion and provide unhindered oil production in a well. The well, located offshore Sarawak Malaysia, was a single string oil producer completed in 1987 with gravel pack and screens. It was a producing well for several years until the gravel pack completion failed and the well started to produce excessive sand. The well was beaned down (BD) to achieve an acceptable sand production limit by the operator of below 15 pound per thousand barrels (pptb). The initial remedial sand control measure was to install a thru-tubing screen, hung inside the production tubing. The thru-tubing screen failed to control the formation sand and a second 200 micron thru tubing screen was installed. That screen managed to control the sand production at acceptable levels but induced significant pressure drop, which reduced the oil production from the optimum level of production.
Workover (WO) operations would involve pulling the existing completion, and re-gravel packing the zone would be costly. In addition to cost, induced mechanical skin in a gravel pack might not be lower than thru-tubing screen application. Chemical consolidation treatments using solvent-based resins historically have been used successfully as alternatives to remedial sand control, although their application, has typically been limited to short intervals.
An aqueous based consolidation resin was developed that provides some advantages compared to conventional solvent based resin systems. The aqueous based resin system uses an internally cured water-based epoxy resin. Unlike the solvent based resin systems, which have a low flash point, the aqueous base consolidation resin system is not flammable. It is safer and less complex operationally. The consolidation-fluid mix can also be foamed for diversion purposes to treat wells with relatively large variations in permeability over longer zones compared to the solvent based resins. This paper describes the treatment background, engineering approach, laboratory testing, fluid design stages, quality assurance/quality control (QA/QC) procedures, and the treatment execution for the chosen well. The field trial showed no sand was produced after treatment. In fact, the production rate was twice that of the production rate with the thru tubing screen in place. The promising result from this well creates new opportunities for simple, environmentally acceptable, and cost-effective remedial sand-control solutions for the operator.
Developments in Sandstone HF Acidizing: HF Fluid Compatible with Na or K Brines and Carbonate-Laden Mineralogy for High Temperatures (360°F)
Authors: Garcia Enrique A. , LaBlanc Alyssa , Beuterbaugh Aaron , Calabrese Tristen 
Published: January 2016

Abstract
Using hydrofluoric (HF) acid for the removal of clays and silica minerals impairing permeability in sandstone formations requires fluids free of sodium or potassium ions. High temperatures (&gt; 300°F) further limit HF acid use and its effectiveness because of potentially damaging effects to the formation and its corrosivity. This paper discusses laboratory testing of an aminopolycarboxylic acid (APCA) fluid containing 1 to 1.5% HF acid and highlights its advantages and differentiating characteristics with respect to previous HF acid fluids.
Core flow testing at 360°F was conducted on outcrops of two types of sandstone representing a heterogeneous (65% quartz and illite/kaolinite with feldspars) and a clean (95% quartz) type of mineralogy. The APCA fluid containing HF acid, which incorporates a modulating agent for the HF acid-secondary reaction on aluminosilicate minerals, was compared to the pure APCA (pH 2) fluid and formic acid. Effluent analysis of the spent fluid was completed by inductively coupled plasma (ICP) optical emission spectroscopy (OES). Corrosion inhibition testing was completed for coiled tubing (CT) and carbon steel (NT-95) up to 360°F, employing various classes of inhibitors.
Using an APCA chelating agent in sandstone HF acidizing expands the temperature range of application and the type of minerals that can be exposed to such fluid. High-temperature HF acidizing is also delimited by the type of steel tubing that can be exposed to such fluid, placing significant demands on corrosion control. Laboratory results obtained in this investigation demonstrate that corrosion can be well managed for a fluid having a pH of 2.5 and HF acid concentrations of 1 to 2% from 250 to 275°F and at 300°F with a pH of 4. Testing results show that the APCA/HF fluid, having a pH of 2.5, can effectively be used to treat heterogeneous sandstone of moderate carbonate content at 360°F and is also compatible with a clean sandstone. The APCA/HF fluid stabilizes the most problematic ions in the spent fluid—Al3+, Fe2+/3+, Ca2+, and alumino-fluorides—without the need for acid preflushes and without maintaining highly acidic conditions. Comparison to formic acid and HF acid-free APCA fluid is presented.
Using aminopolycarboxylic acid-type chelants is restricted by the materials commercially available, all of which contain sodium, with one exception, which has ammonium. Hence, HF acidizing has been restricted to ammonium-containing fluids. A differentiating characteristic of the fluid reported here is its ability to sustain Na+ concentrations exceeding 1 M and K+ concentrations in excess of 0.5 M. Furthermore, it is suitable for the treatment of carbonate-laden mineralogy formations up to 360°F.
Iron Sulfide Scale Deposition in Deep Sour Reservoirs
Authors: Ma Jun , Fuss Tihana , Shi Jingyu 
Published: January 2016

Abstract
Crude oil and natural gas can carry various high-impurity products which are inherently corrosive, such as, carbon dioxide (CO2) and hydrogen sulfide (H2S). These impurities increase operational safety risk and can be detrimental to production, both in terms of equipment damage and permeability impairment caused by scale deposition. Problems with iron sulfide scale occur when H2S comes in contact with spent acid solutions containing dissolved iron ions. While dissolution of pipe and iron bearing core materials in H2S solutions is known to result in FeS scale deposition, the reactivity of iron containing proppant material under sour conditions is poorly understood and documented.
The present study evaluates and compares dissolution kinetics of iron bearing formation and ceramic proppants, which were derived from multiple sources of bauxite minerals, in H2S acid solution in order to evaluate their relative contributions to iron sulfide scale deposition. The study uses X-ray diffraction (XRD) and inductively-coupled plasma optical emission spectroscopy (ICP-OES) analysis to qualify Fe containing crystallite forms and quantify dissolution and scale build up reaction kinetics. Scanning Electron Microscopy (SEM) is used to evaluate surface morphology changes associated with iron dissolution and iron sulfide scale deposition. Finally, reactivity of all tested materials is compared based on their initial iron concentration and relative dissolution affinity.
An Integrated Study of Mud Plastering Effects for Reducing Filtrate's Invasion
Authors: Ezeakacha C. , Salehi S. , Ghalambor A. , Karimi M. 
Published: January 2016

Abstract
Drilling fluid's filtration and mud cake build up is often cited as one of the key factors where operators observed better control of lost circulation from one well to another. Although this may sound a routine and simplistic process, it is quite complex. To understand a true synthesis of mud cake build up, one needs to study effects of mud composition, viscosity, and fluid mechanics involved, filtration permeability, and erosion and depositional factors. In addition of these factors, there are effects of time, pressure and temperature.
In this study, a synthesis of mud filtration and mud cake build up by conducting laboratory experiments is presented. The study presents results for Non-aqueous Oil Based Muds (OBM). The methodology depends on conducting Permeability Plug Testing (PPT), SEM and EDS analysis of mud filtrates and mud cakes. We present analysis in different time spans to capture time effects for tests in high pressure and temperature conditions. Other experimental variables in this work are permeability and heterogeneity of filtration medium which are implemented by using different rock disks.
A combination of SEM study of filter-cake structures with the evaluation of experimentally determined fluid loss data leads to a better understanding of the basic principles of filter-cake buildup and formation damage. The key findings from this study are the effects of filtration medium on cumulative mud filtrate loss, invasion and mud cake characterization, and its permeability. This could not be achieved by using ceramic disks traditionally used for PPT experiments. Effects of core permeability variation on mud invasion under high pressure and high temperature conditions have been illustrated.
Consolidating Sand with New Generation Zeta Potential Altering Systems
Authors: Treybig D. S. , Saini R. , Vigderman L. , Smith K. , Gray B. , Strobel J. 
Published: January 2016

Abstract
This paper describes a new zeta potential altering system (ZPAS) that is based on an inner salt developed between an organic polymer (OP) and an ester for fines, sand and proppant flowback control. The objective of this work was to develop a ZPAS with an enhanced environmental profile and better product performance as it relates to intensity of particle agglomeration and thermal stability under wide range of downhole operating conditions.
The effect of molecular weight of the organic polymer after blending with different esters on zeta potential, rheology, agglomeration, fines production, sand production, regain permeability, fracture conductivity, flash point and EC50 concentration was investigated and compared to the performance of the existing ZPAS. Zeta potential was measured using a Zetasizer Nano Z System manufactured by Malvern, rheology with Anton Paar and ARES G2, sand production with a Maximum Sand Free Rate (MSFR) Test, regain permeability with a Chandler Engineering Formation Response Tester, fracture conductivity, indentation force with a Texture Analyzer, flash point with Miniflash FLP/FLPH/FLPL and EC50 concentration with a Modern Water Microtox Model 500 Analyzer.
When the organic polymer was blended with an ester, the odor was minimized substantially and toxicity reduced 400 times as compared to the current ZPAS. This organic polymer has a considerably higher molecular weight than the prior oligomeric ZPAS system. 1 This molecular weight enhancement improves the degree of agglomeration as measured by indentation testing and provides better thermal stability. Force in grams as measured with the indentation tester increased as the organic polymer concentration and molecular weight was increased in the new ZPAS formulation. The force in grams is an indicator of the effectiveness of sand consolidation. There was no sand produced at 180° F with 20/40 mesh sand and a confining pressure of 400 psi in the MSFR test. Regain permeability of 60 to 82% was obtained in low permeability sandstone. High MW ZPAS was more effective than medium MW ZPAS at 2,000 psi closure stress while medium MW ZPAS was more effective at 6,000 psi closure stress. The oscillatory rheometer indicated that the polymeric ZPAS is a Newtonian fluid which makes it easy to pump. After sand is agglomerated with the ZPAS, the agglomerated sand becomes viscoelastic. The elasticity is maintained to a temperature of at least 180°F. The stronger sand consolidation and more deformable agglomerate provided by this new generation ZPAS as compared to the current ZPAS is useful in producing more oil without incremental sand production.
Injectivity Impairment During Produced Water Disposal into Low-Permeability Völkersen Aquifer (Compressibility and Reservoir Boundary Effects)
Authors: You Z. , Kalantariasl A. , Schulze K. , Storz J. , Burmester C. , Künckeler S. , Bedrikovetsky P. 
Published: January 2016

Abstract
Compressibility needs to be accounted for when estimating injectivity decline for water disposal in gas reservoirs and in closed aquifers, and for waterflooding of gas-condensate fields. The problem with given wellbore pressure at the injector aims avoiding the reservoir fracturing. An analytical model is developed that provides well injectivity index decline with time. Under this model, the solution of damage-free compressible flow in a closed reservoir is asymptotically matched with the impedance growth formulae for incompressible flow in the well vicinity. For the well regime of a given wellbore pressure, the injection rate decline is described by a nonlinear integro-differential equation that is solved iteratively. The solution under the field conditions investigated shows that well impedance grows faster during deep bed filtration than during external cake formation. This unusual pattern is explained by low permeability of the reservoir. Well impedance is more sensitive to the effect of formation damage than to the compressibility effect of rock and water. Lower formation damage, higher compressibility, or lower injected particle concentration results in larger total injection volume into a closed reservoir.
Molecular Dynamics Simulations of Asphaltene Dispersion by Limonene and PVAc Polymer During CO2 Flooding
Authors: Sedghi Mohammad , Goual Lamia 
Published: January 2016

Abstract
Asphaltene precipitation during miscible CO2 flooding can adversely affect the productivity of reservoirs during the course of oil recovery. The prevention of formation damage ensuing from asphaltene deposition in porous rocks often requires the use of chemical additives such as solvents or inhibitors. Effective additives are able to disperse asphaltene aggregates by curbing their growth in the bulk phase. While numerous dispersion studies have been performed in alkane solvents, very limited work currently exists in supercritical (sc) carbon dioxide. The main challenge stems from the inherent insolubility of a large number of additives in sc-CO2. The objective of this study is to investigate the molecular interactions between asphaltenes and two environmentally friendly additives in sc-CO2 at 308 K and 300 bar using molecular dynamics (MD) simulations. The additives consist of a terpene solvent (d-limonene) and a common viscosifier (polyvinyl acetate or PVAc). Two similar asphaltene structures (with and without hydroxyl group) were designed in order to understand the role of hydrogen bonding in their aggregation behavior. The results indicate that d-limonene can only disperse non-hydrogen bonding asphaltenes when used in sufficient amounts (i.e., 30 wt%). The interactions between hydrogen bonding asphaltenes and PVAc polymer (5 wt%) significantly reduced their aggregation but lowered the solubility of the polymer in sc-CO2. Adding limonene to this mixture could remediate the phase change and maintain asphaltenes and PVAc completely dispersed in the system.
Multi‐Profile Analysis of Soil Moisture within the US Climate Reference Network
Authors: Coopersmith E.J. , Cosh M.H. , Bell J.E. , Crow W. T. 
Published: January 2016

Core Ideas
Hydraprobe measurements can be quantified.
USCRN gauges distributed nationally are analyzed.
Random error magnitudes are a function of how recently precipitation has occurred.
Soil moisture estimates are crucial for hydrologic modeling and agricultural decision‐support efforts. These measurements are also pivotal for long‐term inquiries regarding the impacts of climate change and the resulting droughts over large spatial and temporal scales. However, it has only been the past decade during which ground‐based soil moisture sensory resources have become sufficient to tackle these important challenges. Despite this progress, random and systematic errors remain in ground‐based soil moisture observations. Such errors must be quantified (and/or adequately minimized) before such observations can be used with full confidence. In response, this paper calibrates and analyzes US Climate Reference Network (USCRN) profile estimates at each of three sensors collocated at each USCRN location. With each USCRN location consisting of three independent, Hydraprobe measurements, triple collocation analysis of these sensory triads reveals the random error associated with this particular sensing technology in each individual location. This allows quantification of the accuracy of these individual profiles, the random errors associated with these measurements in different geographic locations, and offers the potential for more adept quality control procedures in near real time. Averaged over USCRN gauge locations nationally, this random error is determined to be approximately 0.012 m3/m3.
Tangent Line/Second‐Order Bounded Mean Oscillation Waveform Analysis for Short TDR Probe
Authors: Wang Zhuangji , Lu Yili , Kojima Yuki , Lu Songtao , Zhang Meng , Chen Yan , Horton Robert 
Published: January 2016

Core Ideas
• A new method for analyzing TDR waveforms is presented.
• The method provides consistent results on waveforms obtained from short TDR probes.
• The method is stable enough for automatic implementation on large sets of TDR waveforms.
Tangent line (TL) methods and the second‐order bounded mean oscillation (BMO) method have been proposed for determining the reflection positions of time domain reflectometry (TDR) waveforms, especially for short‐probe TDR sensors. However, the accuracy of TL methods is limited by the multi‐reflection effects of the short‐probe TDR sensor, and an automatic implementation of the second‐order BMO is challenging because of the superimposition of the TDR waveforms. In this study, we combined a TL method with second‐order BMO to develop a tangent line/second‐order bounded mean oscillation (TL‐BMO) method. Laboratory and field data were used to evaluate the TL‐BMO method. Separate tests were performed on laboratory data to compare the TL‐BMO method with the TL method and the second‐order BMO method. For selected waveforms, the TL‐BMO was more accurate than the TL method (the RMSE of TL‐BMO was 0.0197 m3 m−3 and the RMSE of the TL method was 0.1071 m3 m−3). The TL‐BMO was able to avoid calculation errors associated with automatic analysis by the second‐order BMO (RMSE of TL‐BMO automatic analysis was 0.0199 m3 m−3 and the RMSE of second‐order BMO automatic analysis was 0.1414 m3 m−3). For analyzing field measurements, the TL‐BMO method was able to determine soil water contents accurately during a 3‐wk‐long measurement period. Conclusively, the new TL‐BMO method was more accurate than the TL method, and it demonstrated the stability necessary for automatic analysis of short‐probe TDR sensors.
Disentangling the Effects of Land Management and Soil Heterogeneity on Soil Moisture Dynamics
Authors: Hohenbrink Tobias L. , Lischeid Gunnar , Schindler Uwe , Hufnagel Johannes 
Published: January 2016

Core Ideas
We performed time series analysis of existing large soil moisture data sets.
Observed behavior was decomposed into respective contributions of single processes.
Considering input signal transformation instead of mass flux considerations.
Our approach opens many new possibilities to analyze complex soil system behavior.
Soil moisture is the essential control of water and energy dynamics at arable sites. Time series of soil moisture reflect the interplay of various processes, each of which influences the overall soil moisture dynamics. In this study we tested an approach to break down observed soil moisture behavior into the respective contributions of individual processes. We applied a principal component analysis to soil moisture time series from a field experiment comprising two crop rotation systems and two different soil tillage practices. We concentrated on 57 soil moisture time series measured over nearly 4 yr at 12 plots and five soil depths, down to 1.5 m. About 77.9% of the variance was reflected by the first component being almost identical to a time series of averaged soil moisture. It described the effect of the meteorological boundary conditions. The second component described the effect of the input signal damping increasing with soil depth and accounted for 7.8% of total variance. The signal transformation over depth proved to be more or less uniform throughout the test site, despite considerable soil heterogeneity. Another 3.6% of the total variance (third component) was unambiguously explained by the different cropping systems. On the contrary, different soil tillage practices had no significant effect. The suggested approach opens up many possibilities to analyze and better understand complex soil system behavior. The data‐based approach of time series analysis provides model‐independent, quantitative information about the key factors and processes controlling soil water dynamics. Hence, it is especially valuable for model building, calibration, and evaluation.
Non-commutative finite monoids of a given order n ≥ 4
Authors: Ahmadi B. , Campbell C.M. , Doostie H. 
Published: January 2016

Abstract
For a given integer

n
=

p
1

α
1

p
2

α
2

⋯

p
k

α
k

$n = p_1^{\alpha _1 } p_2^{\alpha _2 } \cdots p_k^{\alpha _k }$

(k ≥ 2), we give here a class of finitely presented finite monoids of order n. Indeed the monoids Mon(π), where

π
=

〈

a
1

,

a
2

,
…
,

a
k

|

a
i

p
i

α
i

=

a
i

,

(

i
=
1
,
2
,
…
,
k

)

,

a
i

a

i
+
1

=

a
i

,

(

i
=
1
,
2
,
…
,
k
−
1

)

〉

.

$$\pi = {\langle {a_1 ,a_2 , \ldots ,a_k |a_i^{p_i^{\alpha _i } } = {a_i}, {\left({i = 1,2, \ldots ,k} \right)}, a_i a_{i + 1} = {a_i}, \left({i = 1,2, \ldots ,k - 1} \right)} \rangle} .$$

As a result of this study we are able to classify a wide family of the k-generated p-monoids (finite monoids of order a power of a prime p). An interesting di erence between the center of finite p-groups and the center of finite p-monoids has been achieved as well. All of these monoids are regular and non-commutative.
Determinant Identities and the Geometry of Lines and Circles
Authors: Anghel Nicolae 
Published: January 2016

Abstract
The focus of this note is the nontrivial determinant identities which typically underlie the complex analytic proofs of all the results in the plane geometry of lines and circles. After setting up a basic dictionary relating lines and circles to complex determinants we derive such identities in connection with four geometry problems: the Steiner line, a variant of Euler’s nine-point circle, the Johnson-Tzitzeica circles, and an extension of a certain geometry problem, proposed at the 52nd International Mathematical Olympiad, Amsterdam 2011.
A Krull-Schmdit type theorem for coherent sheaves
Authors: Argáez A. S. 
Published: January 2016

Abstract
Let X be projective variety over an algebraically closed field k and G be a finite group with g.c.d.(char(k), |G|) = 1. We prove that any representations of G on a coherent sheaf, ρ : G → End(ℰ), has a natural decomposition ℰ ≃ ⊕ V ⊗
k
ℱ
V
, where G acts trivially on ℱ
V
and the sum run over all irreducible representations of G over k.
Some remarks on limit mixed Hodge structures and spectrum
Authors: Dimca Alexandru , Saito Morihiko 
Published: January 2016

Abstract
In this note we clarify some subtle points on the limit mixed Hodge structures and on the spectrum. These are more or less well-known to the specialists, but do not seem to be stated explicitly in the literature. However, as they do not seem to be obvious to the beginners, we consider them to be worth writing down explicitly. The general constructions are exemplified by considering the isolated (weighted) homogeneous singularities in detail.