bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on Enhanced Oil Recovery Technology in Low Permeability Heterogeneous Reservoir by Water-Alternate-Gas of CO2 Flooding
Authors: Chang-lin Liao , Xin-wei Liao , Xiao-liang Zhao , Ning Lu , Hong-na Ding , Huan Wang , Yong-ge Liu 
Published: October 2013

Abstract
The common problems that water injection come across in low permeability heterogeneous oil reservoir are poor injectability, low production, high water cut and low oil recovery. The previous studies showed that Water-Alternate-Gas (WAG) of CO2 flooding could enhance oil recovery in low permeability oil reservoir effectively. However, the way to use effective technology to enhance oil recovery and net present value (NPV) in low permeability heterogeneous oil reservoir became a difficult point in WAG flooding. This paper introduces allocation of injection rates (AOIR), tapered Water-Alternate-Gas (TWAG) and AOIR-TWAG to study the feasibility of the technologies in enhancing oil recovery with numerical reservoir simulation base on the previous studies. The development effects of constant WAG in the reservoirs with different variation coefficients were contrasted. And the feasibility of the three technologies to enhance oil recovery was studied. The results show that the development effect of constant WAG flooding is better than that of continuous gas injection with the increasing of the variation coefficient. And the oil recoveries of the three technologies are better than that of the constant WAG flooding. However, only the NPV of the AOIR and AOIR-TWAG are better than that of constant WAG flooding. An actual oil reservoir model of Xinjiang oil field in China was used to check the feasibility of the two technologies. The results show that the oil recoveries and NPVs of the two technologies are better than that of constant WAG flooding. This result proves that the conclution of the reservoir conceptual model is reliable, and the technology could be suitable for other similar low permeability heterogeneous oil reservoirs.
Organic Deposition: From Detection and Laboratory Analysis to Treatment and Removal
Authors: Alian Sima Sheykh , Singh Kulwant , Saidu Mohamed Anwarudin , Ismail M. Zaki , Anwar Mona Liza 
Published: October 2013

Abstract
Organic deposition predominantly in the near well bore and in production tubing can create serious oilfield problems such as flow restrictions, near wellbore damage, efficiency of crude processing units and etc. As the reservoir depleted over the time, the solid deposition can lead to a steep decline in productivity of wells. The deposition of organic solids is one of many flow assurance problems faced by operators in Malaysia. It has been observed that, after years of production, many fields in Malaysia are suffering from organic solid deposition problem. This phenomenon is predominantly caused by changes in temperature, pressure and composition/morphology of the crude oil over time. To perform organic deposit removal treatment and prevention in the well, the nature of the solid should be characterized. If the deposit sample is organic mainly, it is important to quantify the various organic fractions of the solid sample collected from the production facilities. This paper explains how SARA analysis was modified to detect not only Macro-crystalline waxes (Saturates), asphaltene, aromatics and resins but also micro-crystalline wax and naphthenates. The content of each of above component will affect the method of treatment and the chemical formulation to treat the well. By knowing the composition of the solid sample along with Crude’s Colloidal instability index (CII), Pour point and Wax Appearance Temperature (WAT), a customized chemical formulation can be designed. Lab studies were performed on solid samples collected from several wells to detect the flow assurance related issues prior to design of chemical formulation. With the analysis of the production data, history matching, and etc, a customized chemical formulation was developed to treat the wells. The proposed chemical formulation consists of 2 specially designed pills which would be simultaneously injected to the wellbore, which generates heat and ester once comingles. The heat melts the deposits while the ester disperses the melted solid. The initial studies of the treatment showed promising results; moreover the field implementation was very successful and proven significant increase in production rate. This novel system that combines both thermal and physical energy, evidenced to work effectively for wide range of organic compositions. Implementation of this system made it possible to restart the production from those wells which were idle due to extensive organic deposits. This technique was also often used to rejuvenate the old wells with low production rate. This paper discusses the diagnostic process and successful implementation of the proposed treatment in several oil wells in Malaysia.
Field and Numerical Simulation Study on Stereoscopic Network Development at Later Cyclic Steam at Thick Heavy-Oil Reservoir
Authors: Lu Sun , Liu Yuetian , Chen Minfeng , Li Xiaofeng , Zhang Hairu , Guo Zhengliang , Ge Taotao 
Published: October 2013

Abstract
Heavy-oil occurring in thick reservoir is an important resource world-wide. Heavy-oil recovery from such reservoir using cyclic steam is an efficient solution due to very high oil viscosity. However heavy oil recovery at later cyclic steam soaking is a real challenge, yet no direct analogues exists as an efficient solution.
We proposed a new method called stereoscopic network development and needed for efficient heavy-oil recovery from thick reservoir, consisting of ten vertical wells and two horizontal wells in the following manner:
1. Stereoscopic network: adding two superposed horizontal wells between vertical wells in rectangular pattern.
2. Operation: steam injection through the upper horizontal well and production through the lower and all vertical wells.
Field practices of managing a steam flood with stereoscopic network in thick reservoir has shown that oil production and oil-steam ratio increased obviously, and water cut decreased sharply.
In this work, the field results obtained early and parameters were needed for field scale simulation. The numerical model has been developed by CMG simulation software and was validated with field data. Using field results and numerical simulations study on stereoscopic network development, the mechanism of stereoscopic network to enhanced heavy-oil recovery in thick reservoir has been studied theoretically and with field test results. And field scale simulations were performed to identify the efficiency of the new method and the optimal injection/production schemes. Specific conclusions as to how to apply the method in thick reservoir considering the effect of the method were reported.
Innovative Modeling System Develops New PDC Bit Technology: Saves Operator 55% Drilling Time in First Deep Jurassic Slimhole Development Well, Kuwait
Authors: Al-Enezi Dakhel , Al-Khaldy Ali , Al-Mutawa Faisal , Al-Mkhyal Abdullah , Maliekkal Harish , Ghoneim Osama , Saleh Mustafa 
Published: October 2013

Abstract
The North Kuwait Development Project requires a large-hole casing design to isolate problematic formations and enable the operator to reach deep HPHT target zones with maximum hole size. The most difficult section is Zubair to Hith traditionally drilled with 16" bits. These formations consist of abrasive/pyritic sandstone, reactive shale and carbonates with UCS between 5-30kpsi. Historically, to complete the 3900ft section required more than three PDCs or a combination of 4-5 PDC/TCI.
To reduce costs, the first slimhole development well plan and string design was developed for Northern Kuwait fields. The objective would be to downsize the hole section from Zubair to Hith to 9¼" and drill to section TD with three PDCs. The production casing would be run from surface to TD instead of the conventional liner tie-back.
To accomplish the objective, the team decided to develop two different 9¼" PDCs: 1) one for Zubair to Ratawi shale; 2) a second for drilling the remaining carbonates from Ratawi to Hith. To avoid costly field trials, an FEA-based modeling system was used to fully understand how iterative bit design changes would affect performance and drilling efficiency. Based on modeling, two PDC bits were implemented: a M819 with back-up cutters to achieve maximum durability and ROP through Zubair and push deep into Ratawi; a M616 to drill the remaining section from Ratawi to Hith. The bits were equipped with the latest HTHP cutters to enhance durability/ROP.
The section was completed on a motor BHA in two bit runs saving 55% drilling time and the expense of a third bit. The operation set a new Kuwaiti record for the single longest 7¾" production casing string (13,625ft) and cementing back to surface. The downsizing strategy and increased drilling efficiency saved the operator $1 million USD compared to project estimates and a standard liner-string design.
Adding System Optimisation of Corrosion Inhibitor in Oil Producer in CoFlooding Field Test
Authors: Feng Wang , Changyu Liu , Feng Ma , Tianjie Huang , Weiran Dong 
Published: October 2013

Abstract
CO2 corrosion is one of the key factors that restrain CO2 flooding. Corrosion damage by CO2 breakthrough and water content increase has greatly influence the regular production of oil field. To protect the casing pipe, tubing, sucker rod and deep well pump entirely, inhibitor control technology which uses chemical method as the principal method is needed.
At present, filling inhibitor into the casing-tubing annular is used for anti-corrosion, however, adding rests can be influenced by many factors. According to varied environment of CO2 flooding oil field and the study of inhibitor property and residual concentration, a weak-absorption film former inhibitor used in the CO2 flooding well has been chosen by the lab test evaluation and field experience; dosing concentration, dosing circle and dosing method also have been optimized. All of these works help establish a reasonable inhibitor filling system, as well as improve the dosing efficiency and the pertinence of anti-CO2 corrosion.
After being injected in the CO2 flooding well, the inhibitor caused effect of decreasing corrosion damage, as well as reducing the cost. According to the corrosion monitoring and residual concentration test, when the corrosion ratio is lower than 0.076mm/a, there will be no corrosion in the well bore and the downhole tools. This comprehensive anti-corrosion method can meet the field needs.
Keywords: anti-CO2 corrosion, inhibitor, dosing method, dosing circle
Multi-stage Horizontal Fracturing in Casing for Low Permeability Reservoirs
Authors: Qinghai Yang , He Liu , Jianwen Yan , Gao Yang 
Published: October 2013

Abstract
In recent years, the low permeability reserves account for over 70% of the annual new reserves of PetroChina. In 2009, the annual producing reserves and the new drilled wells of the low permeability reservoirs accounted for 70% of the total number, respectively. The low permeability and non-conventional reservoirs are characterized by high percolation resistance and poor connectivity, and may yield commercial value only after acidizing or fracturing. However, the production of acidized or fractured vertical wells is still low and the benefit is poor. The horizontal wells have the advantages of large drainage area and low pressure drop, which make the multi-stage horizontal fracturing an effective technology for the development of low permeability and non-conventional reservoirs. Most of the horizontal wells of PetroChina low permeability reservoirs are completed with casings to meet the requirement of water injection, thus the technology of horizontal fracturing in casing is crucial for improving recovery efficiency. Three principal techniques of multi-stage fracturing were developed, i.e., double-packer single-slip, packer-sliding sleeve, and hydraulic sandblast, together with four matching techniques such as multi-stage stimulation with chemical temporary-blocking gel plug, high efficiency self- diverting acidizing or acid-fracturing technique of carbonate reservoir, hydraulic fracture monitoring and evaluation, and horizontal well workover. In addition, an optimization method of fracture and well pattern was also proposed. The 3 principal techniques, 4 matching techniques, and the optimization method, effectively promoted the industrial application of horizontal wells in low permeability reservoirs.
Economic Evaluation of Volcanic Gas Production Project in Songliao Basin
Authors: qing Xu , zhisheng Yang , fuli Chen , shuyun Liu , shuqin Chen , min Zhong 
Published: October 2013

Abstract
Large amount of nature gas reserve has been found in the deep formations of volcanic gas reservoir in recent years in Songliao Basin, north-east of China. Because of its complicated geological condition, reservoir characteristics and obscurity of knowledge of the people, economic evaluation becomes a crucial measurement in order to insure the feasibility of the gas production projects. Take Changshen area of Jilin gas field as an illustration, discounted cash flow (DCF) model was used, net present value, interior rate of return and payout time was selected as economic indicator. The CAPEX and OPEX were assessed based on engineering schedules. The operating conditions and production profile were optimized by using reservoir engineering numerical simulation. Other parameters, such as gas price, tax rate, discount rate etc. were coming from the rules and regulations of the government. The results indicate that the economic benefit of the project is marginal. Project feasibility, as expected, was found to be very sensitive to gas price, gas production, and CAPEX. Project financial analysis indicates a couple of key points which may affect the development of volcanic gas reserve, (1) a significant increase of CAPEX and OPEX was found, which are obviously higher than the ordinary reserve’s, (2) CO2 may be used as a byproduct and increase the project’s income only it has its commercial purpose, (3) no preferential policy of carbon emission reduction in China, and (4) local gas price is on the low side. Finally, several suggestions are presented in this paper (1) formulate the various terms of the tax credit policy, (2) enact relevant rules and regulations of carbon emissions trade, (3) foster the local industrial gas market to increase the gas price, and (4) increase the financial input into the critical research of the development technique of volcanic gas reserve.
Efficacy and Safety of Rituximab in Biologic-Naive Patients with Rheumatoid Arthritis vs Anti-Tnf Therapy Failure
Authors: Gutierrez-Gonzalez Luis Arturo , Gudiño Marco Antonio Rivera , Ceija Ibell Oropeza , Leonet Marialina Marin , Noguera Zair Tovar 
Published: October 2013

Objectives:Our aim was to compare an AntiCD20 therapy (rituximab) for rheumatoid arthritis in two patient populations (Group 1), anti-TNFα naïve patients and inadequate responders to Anti-TNFα therapy (Group 2).Methods:We analyzed the efficacy of the drug Rituximab (RTX) in RA patients who failed methotrexate (MTX) or had a relative or absolute contraindication to receive anti-TNFα therapy.Results:25 patients were identified according to the above criteria and followed up for a mean period of 6 months. Thirteen patients were biologic naïve and twelve patients had already failed anti-TNFα therapy. Group 1 used 2> DMARDs (32%vs20%, p<0.005), group 2 had more years of disease progression (5±1.89v s4.10±3.92, p<0.001). The remission as measured by the DAS28 reached faster in group 1 (1.25±0.12vs2.15±1.64, p<0,001). Severe infections especially by herpes viruses were more frequent in group 2.Conclusions:Comparing clinical improvement in both groups the decrease of acute phase reactants and the clinical remission measured by DAS28 was reached in both groups, however it was reached more belatedly in group 2 (at 6 months), this is due to the fact that they have more years of the disease evolution and a higher HAQ.
An investigation into bisphenol-A leaching from orthodontic materials
Authors: Kotyk Matthew W. , Wiltshire William A. 
Published: October 2013

ABSTRACT

Objective:
To quantitatively determine the bisphenol-A (BPA) leached from orthodontic materials during simulated intraoral exposure.

Materials and Methods:
Samples of orthodontic materials were subjected to simulated abrasion, immersion in artificial saliva, thermal shock via temperature cycling, and simulated intraoral exposure. Sample aliquots were collected for up to 2 weeks after artificial saliva immersion, derivatized, then analyzed for BPA by gas chromatography/mass spectroscopy.

Results:
Quantifiable amounts of leached BPA were observed from a thermoformed orthodontic retainer material (7.63 µg/g of material) and an orthodontic adhesive (2.75 µg/g of material). BPA leaching was only observed within the first 3 days of artificial saliva immersion.

Conclusions:
Under the test conditions, BPA was observed to leach from two orthodontic materials. While the quantities of leached BPA were below the reference dose for daily intake, existing data of low-dose effects and medical disorders associated with elevated urinary BPA levels suggest that BPA exposure, and thus the use of the leaching materials identified in this study, should be reduced or eliminated.
Polymerization Shrinkage of Different Types of Composite Resins and Microleakage With and Without Liner in Class II Cavities
Authors: Karaman E , Ozgunaltay G 
Published: October 2013

SUMMARY

Aim
To determine the volumetric polymerization shrinkage of four different types of composite resin and to evaluate microleakage of these materials in class II (MOD) cavities with and without a resin-modified glass ionomer cement (RMGIC) liner, in vitro.

Materials and Methods
One hundred twenty-eight extracted human upper premolar teeth were used. After the teeth were divided into eight groups (n=16), standardized MOD cavities were prepared. Then the teeth were restored with different resin composites (Filtek Supreme XT, Filtek P 60, Filtek Silorane, Filtek Z 250) with and without a RMGIC liner (Vitrebond). The restorations were finished and polished after 24 hours. Following thermocycling, the teeth were immersed in 0.5% basic fuchsin for 24 hours, then midsagitally sectioned in a mesiodistal plane and examined for microleakage using a stereomicroscope. The volumetric polymerization shrinkage of materials was measured using a video imaging device (Acuvol, Bisco, Inc). Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U-tests.

Results
All teeth showed microleakage, but placement of RMGIC liner reduced microleakage. No statistically significant differences were found in microleakage between the teeth restored without RMGIC liner (p&gt;0.05). Filtek Silorane showed significantly less volumetric polymerization shrinkage than the methacrylate-based composite resins (p&lt;0.05).

Conclusion
The use of RMGIC liner with both silorane- and methacrylate-based composite resin restorations resulted in reduced microleakage. The volumetric polymerization shrinkage was least with the silorane-based composite.
Effective protocol for preparation of three-atom Greenberger-Horne-Zeilinger state and W state with the help of cross-Kerr nonlinearity
Authors: Kang Yi-Hao , Xia Yan , Lu Pei-Min 
Published: October 2013

Abstract
We propose a protocol to generate a Greenberger-Horne-Zeilinger (GHZ) state andWstate by using simple linear elements and quantum nondemolition detectors (QNDs). With the help of cross-Kerr nonlinearity, our protocol can generate the intended states with only one setup, and the probability of getting a W state is greatly increased when compared with previous schemes [Phys. Rev. A 75 (2007) 044301]. Also, our proposed protocol is realizable in experiments.
Scattering of longitudinal waves (sound) by defects in fluids. Rough surface
Authors: Apostol Bogdan 
Published: October 2013

Abstract
The classical theory of scattering of longitudinal waves (sound) by small inhomogeneities (scatterers) in an ideal fluid is generalized to a distribution of scatterers and such as to include the effect of the inhomogeneities on the elastic properties of the fluid. The results are obtained by a new method of solving the wave equation with spatial restrictions (caused by the presence of the scatterers), which can also be applied to other types of inhomogeneities (like surface roughness, for instance). A coherent forward scattering is identified for a uniform distribution of scatterers (practically equivalent with a mean-field approach), which is due to the fact that our treatment does not include multiple scattering. The reflected wave is obtained for a half-space (semi-infinite fluid) of uniformly distributed scatterers, as well as the field diffracted by a perfect lattice of scatterers. The same method is applied to a (inhomogeneous) rough surface of a semi-infinite ideal fluid. A perturbation-theoretical scheme is devised, with the roughness function as a perturbation parameter, for computing the waves scattered by the surface roughness. The waves scattered by the rough surface are both waves localized (and propagating only) on the surface (two-dimensional waves) and waves reflected back in the fluid. They exhibit directional effects, slowness, attenuation or resonance phenomena, depending on the spatial characteristics of the roughness function. The reflection coefficients and the energy carried on by these waves are calculated both for fixed and free surfaces. In some cases, the surface roughness may generate waves confined to the surface (damped, rough-surface waves).
Radiography and biomechanics of sixth and seventh cervical vertebrae segments after disc fenestration and after insertion of an intervertebral body spacer
Authors: Desquilbet L. , Fitzpatrick D. , Bernard F. , Moissonnier P. 
Published: October 2013

SummaryObjectives: To study the radiographic characteristics and the biomechanical properties of the sixth and seventh cervical (C6–C7) vertebral motion unit (VMU) with an intact disc, after disc fenestration, and after placement of an intervertebral body spacer (IVBS).Methods: Six cadaveric C6-C7 VMU were retrieved from six Greyhound cadavers. Each VMU was loaded at 3 Nm of torque sequentially in flexion, extension, and in right and left lateral bending. The range-of-motion (ROM) was measured with a Zebris 3D® system. The intervertebral disc cross-sectional area was measured on lateral and ventrodorsal radiographs. Biomechanical testing and radiographic measurements were performed with an intact disc, after disc fenestration, and after IVBS placement. Data were reported as mean ± SD.Results: The intervertebral disc cross-sectional area was significantly decreased after disc fenestration and increased after IVBS placement, but remained significantly smaller than the area of intact disc in some of the tested conditions. The ROM with an intact disc, after disc fenestration and after IVBS placement, in flexion were 11.5° ± 1.0, 15.2° ± 2.3, and 10.9° ± 4.7, respectively, and in extension were 15.6° ± 3.7, 24.7° ± 6.2, 21.9° ± 4.0, respectively. There was a significant increase in extension ROM after disc fenestration. Intervertebral body spacer placement significantly decreased ROM in flexion but ROM in extension was not different from disc fenestration. No significant changes in lateral bending ROM were detected.Clinical significance: The use of an IVBS reduced disc space collapse but did not restore stability of the VMU to normal values in extension after cervical disc fenestration.