bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endoprosthetic replacement for primary tumours around the knee
Authors: Guo W. , Ji T. , Yang R. , Tang X. , Yang Y. 
Published: July 2008

In developing countries locally-made low-cost prostheses are mainly used in limb-salvage surgery to alleviate the economic burden. We retrospectively collected data on 104 patients treated by limb-salvage surgery between July 1997 and July 2005. We used a locally-designed and fabricated stainless-steel endoprosthesis in each case. Oncological and functional outcomes were evaluated at a mean follow-up of 47 months (12 to 118). A total of 73 patients (70.2%) were free from disease, nine (8.7%) were alive with disease, 19 (18.2%) had died from their disease and three (2.9%) from unrelated causes. According to the Musculoskeletal Tumor Society scoring system, the mean functional score was 76.3% (SD 17.8). The five-year survival for the implant was 70.5%. There were nine cases (8.7%) of infection, seven early and two late, seven (6.7%) of breakage of the prosthesis, three (2.9%) of aseptic loosening and two (1.9%) of failure of the polyethylene bushing. Multivariate analysis showed that a proximal tibial prosthesis and a resection length of 14 cm or more were significant negative prognostic factors. Our survival rates and Musculoskeletal Tumor Society functional scores are similar to those reported in the literature. Although longer follow-up is needed to confirm our results, we believe that a low-cost custom-made endoprosthesis is a cost-effective and reliable reconstructive option for limb salvage in developing countries.
A prospective trial comparing the Holland nail with the dynamic hip screw in the treatment of intertrochanteric fractures of the hip
Authors: Little N. J. , Verma V. , Fernando C. , Elliott D. S. , Khaleel A. 
Published: July 2008

We compared the outcome of patients treated for an intertrochanteric fracture of the femoral neck with a locked, long intramedullary nail with those treated with a dynamic hip screw (DHS) in a prospective randomised study. Each patient who presented with an extra-capsular hip fracture was randomised to operative stabilisation with either a long intramedullary Holland nail or a DHS. We treated 92 patients with a Holland nail and 98 with a DHS. Pre-operative variables included the Mini Mental test score, patient mobility, fracture pattern and American Society of Anesthesiologists grading. Peri-operative variables were anaesthetic time, operating time, radiation time and blood loss. Post-operative variables were time to mobilising with a frame, wound infection, time to discharge, time to fracture union, and mortality. We found no significant difference in the pre-operative variables. The mean anaesthetic and operation times were shorter in the DHS group than in the Holland nail group (29.7 vs 40.4 minutes, p < 0.001; and 40.3 vs 54 minutes, p < 0.001, respectively). There was an increased mean blood loss within the DHS group versus the Holland nail group (160 ml vs 78 ml, respectively, p < 0.001). The mean time to mobilisation with a frame was shorter in the Holland nail group (DHS 4.3 days, Holland nail 3.6 days, p = 0.012). More patients needed a post-operative blood transfusion in the DHS group (23 vs seven, p = 0.003) and the mean radiation time was shorter in this group (DHS 0.9 minutes vs Holland nail 1.56 minutes, p < 0.001). The screw of the DHS cut out in two patients, one of whom underwent revision to a Holland nail. There were no revisions in the Holland nail group. All fractures in both groups were united when followed up after one year. We conclude that the DHS can be implanted more quickly and with less exposure to radiation than the Holland nail. However, the resultant blood loss and need for transfusion is greater. The Holland nail allows patients to mobilise faster and to a greater extent. We have therefore adopted the Holland nail as our preferred method of treating intertrochanteric fractures of the hip.
Fracture healing in HIV-positive populations
Authors: Richardson J. , Hill A. M. , Johnston C. J. C. , McGregor A. , Norrish A. R. , Eastwood D. , Lavy C. B. D. 
Published: July 2008

Highly active anti-retroviral therapy has transformed HIV into a chronic disease with a long-term asymptomatic phase. As a result, emphasis is shifting to other effects of the virus, aside from immunosuppression and mortality. We have reviewed the current evidence for an association between HIV infection and poor fracture healing. The increased prevalence of osteoporosis and fragility fractures in HIV patients is well recognised. The suggestion that this may be purely as a result of highly active anti-retroviral therapy has been largely rejected. Apart from directly impeding cellular function in bone remodelling, HIV infection is known to cause derangement in the levels of those cytokines involved in fracture healing (particularly tumour necrosis factor-α) and appears to impair the blood supply of bone. Many other factors complicate this issue, including a reduced body mass index, suboptimal nutrition, the effects of anti-retroviral drugs and the avoidance of operative intervention because of high rates of wound infection. However, there are sound molecular and biochemical hypotheses for a direct relationship between HIV infection and impaired fracture healing, and the rewards for further knowledge in this area are extensive in terms of optimised fracture management, reduced patient morbidity and educated resource allocation. Further investigation in this area is overdue.
Testing the predictive utility of the STATIC‐99: A Bayes analysis
Authors: Beauregard Eric , Mieczkowski Tom 
Published: July 2008

Purpose. This study applies a Bayes analysis to the probability of a particular STATIC‐99 score and its associated re‐offence probability with recidivating for a sexual offence. We examine this probability over three time frames: within 5 years; within 10 years; and within 15 years.Methods. This study was conducted using the same data from Hanson and Thornton (1999). This dataset is constituted from four different samples: Institut Philippe Pinel (Canada) sample; Millbrook Recidivism Study (Canada) sample; Oak Ridge Division of the Penetanguishene Mental Health Center (Canada) sample; and Her Majesty's Prison Service (UK) sample. The final sample for which sufficient information was available to score the STATIC‐99 includes 1,086 sexual offenders. Bayes statistic has been used to analyse the data.Results. Results are consistent with the STATIC‐99 as a useful assessment tool. The Bayes‐generated probabilities as well as odds ratios show a consistent increase in increased likelihood of re‐offence as the score value increases.Conclusions. The Bayesian analysis of the STATIC‐99 shows that this method is very interesting in the context of risk assessment tools. This approach to risk assessment instruments may be more appropriate in the communication of analytic results as it can offer clinicians a combination of probabilities and likelihood ratios resulting a readily accessible profile of risk.
Comparative Evaluation of Temporary Blocking Fluid Systems for Controlling Fluid Loss Through Perforations
Authors: Dorman J. , Udvary F. 
Published: July 2008

Abstract
During completion and workover operations high rate fluid loss is encountered in many wells due to the presence of highly permeable and naturally fractured, depleted formations. Several methods to obtain temporary plugging have been studied to select the most versatile technique for different field conditions. In addition to the laboratory results, field trials have been performed for detailed and comparative evaluation of loss control compositions. These compositions included polymers and sized calcium carbonate systems, polymers and sized micronized (fibrous) cellulose combinations, polymers and sized salt systems (medium and high temperature formulations), crosslinked polymer gel plugs, and delayed swelling, stabilized (extended life) polymer systems. The role of fluid chemistry in prevention of formation damage, extension of gelation temperature, and temperature stability was also investigated. The temperature and differential pressure of the formations (sandstone limestone, conglomerate, metamorfite, etc) varied between 60-170 °C, and 1-15 MPa respectively. Fluid compositions without imposing severe permeability damage were selected, which can be broken down chemically. Case studies of field operations performed in Hungary are also presented.
Enzyme Breaker Adsorption in Sandstones and Coal
Authors: Himes R. E. , Conway M. W. , Schraufnagel R. A. 
Published: July 2008

Abstract
Enzyme type gel breakers have been widely used in completion and stimulation work to reduce the viscosity of various polysaccharide polymers in a controlled manner. Major applications are in gravel packing, fracturing and well control. Mixtures of enzymes are utilized to reduce the polymer strands to low molecular weight fragments for flow back from the formation and wellbore. Recent laboratory studies have found that under certain conditions, enzymes are removed from the polymer solutions by adsorption when injected into sandstone or coal matrices. The implications of this original finding were that gelled fluid lost to these type reservoirs would not break completely and could cause permeability impairment. Continued research found that the phenomenon appeared restricted to hydroxyethylcellulose (HEC) gelling agents and did not occur to a great extent with guar based gels. Fortunately, the presence of an initial oil saturation interferes with the adsorption process except in the cases of low paraffin condensates. Conclusions suggest that care should be taken in application of HEC gels with enzyme breakers in "dry" gas reservoirs and coal seams. Misleading results in laboratory experiments can also result when retained gel samples are used to predict viscosity decline of gel within a core matrix. This is especially true for the practice of using "cleaned" core samples where solvents are used to remove any oil saturation prior to use.
Screening Considerations for Curable Resin-Coated Proppants
Authors: van Batenburg Diederik , Nieuwland Bas , Sandy Joe 
Published: July 2008

Abstract
Curable resin-coated proppants (RCP) have been used to minimize proppant flowback from propped hydraulic fractured oil and gas wells for years, yet proppant backproduction is still reported to be a major operational problem. The industry cannot currently explain why some hydraulic fractures propped with curable RCP produce proppant back while others containing only uncoated proppant do not produce any proppant back.
This paper presents results of a study done to help determine screening considerations for curable resin-coated proppants. The study involved curing and crushing proppant plugs under a variety of conditions ranging from frac-and-pack applications in shallow wells to fracturing applications in deep horizontal wells. These tests were conducted to identify suitable RCPs for given applications.
The unconfined compressive strength (UCS) of proppant plugs cured in the treatment fluid at reservoir temperature with closure stress applied, is currently used as the screening criterion for curable RCP. The UCS needs to be as high as possible while the same resin coating should not consolidate the proppant while left in the well after a treatment without closure stress applied. This study demonstrates that at least six data points are needed to obtain a representative value for the unconfined compressive strength (UCS) of proppant for any one set of conditions. Although several studies of factors affecting the performance of RCPs have been presented in the literature, the conclusions in these studies are generally based on limited data for one set of conditions and are, therefore, often questionable.
In addition, the effect of cooldown and subsequent heatup on RCPs after a treatment has not been considered previously as a factor in proppant backproduction. This paper demonstrates that this temperature effect is an important parameter to consider. Stress cycling has been identified as one of the failure mechanisms for RCP in experiments. These experiments were conducted at ambient temperature with proppant packs cured at temperatures between 160 and 200°F (71 and 93°C). We conducted similar experiments at simulated in-situ conditions to verify whether the mechanism was still effective for these conditions. We found that the addition of thermoplastic film material to RCP cured at 300°F (149°C) increased its resistance to stress cycling.
Effect of Formation Minerals On HEC Gel Return Permeability and Techniques to Overcome Potential Damage
Authors: Hossaini Mohammad , Gabrysch Allen 
Published: July 2008

Abstract
This paper describes the methodology and results of a series of tests conducted on HydroxyEthyl Cellulose (HEC) gel to determine its effects on return permeability. HEC gel is widely used in the oilfield as a carrier fluid in gravel packing operations and is generally considered to cause minimal formation damage. However, results of this study indicate that even when HEC gel is efficiently removed from the formation, interaction between the fluid and the formation can result in reduced return permeability. Therefore, particular care must be given to quality control and mixing procedures to minimize potential formation damage.
HEC gel break-back procedures used by oilfield laboratories for return permeability measurement are based on displacement studies related to reservoir engineering. In these tests, flow through a Berea core is maintained at constant pressure and later, after introduction of the test fluid, the change in permeability is calculated as a percent of the initial permeability. In these cases, any resulting loss of permeability was assumed to be caused by HEC gel trapped in the formation.
To insure complete HEC degradation over time and temperature with and without the presence of formation minerals, seven different breaker systems were evaluated to select the most efficient system.
This study concludes that damage caused by HEC residue is minimal compared to the damage caused by the interaction of the fluid and the rock minerals present in various formations. The results of our investigation also indicate that the performance of breakers is influenced by the presence of formation minerals.
This paper will present experimental data of HEC gel break-back in the presence of formation minerals as well as the testing of chemical additives designed to minimize damage and deliver improved return permeability.
Stabilization of Montmorillonite Clay in Porous Media by Polyacrylamides
Authors: Zaitoun A. , Berton N. 
Published: July 2008

Abstract
The critical salinity concentration (CSC) was used to compare the ability of nonionic polyacrylamides (PAM) and cationic polyacrylamides (CPAM) to stabilize montmoriilonite clay dispersed in sandpacks. The method consists of injecting brine at decreasing salinity levels until clay release is detected by a continuous increase in pressure drop.
As expected, because of the neutralization of negative clay surface charges by adsorbed macromolecules, CPAM have a higher stabilizing power than PAM, lowering the CSC of NaCl from 27 500 to only 500 ppm, and the CSC of KCI from 5000 to 1000 ppm. However, because of their ionicity and very high adsorption level, CPAM strongly reduce sandpack permeability. Likewise, a low-molecular-weight PAM may be preferred because of its good stabilizing power associated with a minimal loss of core permeability.
Multirate Well Testing to Evaluate the Effectiveness of Frac Packing
Authors: McLeod Harry O. , Jordan Scott W. , Shurtz David F. 
Published: July 2008

Abstract
A gas well in the Gulf of Mexico was frac packed with 40/60 mesh gravel using a high temperature borate cross-linked HPG polymer fluid. The flow rate and wellhead pressure were monitored during cleanup. When no further cleanup of fracturing fluid was observed, a multirate test and pressure buildup were conducted on the well. These data were interpreted to give: reservoir permeability and pressure, skin factor, fracture half-length, and fracture conductivity. The multirate testing provided the non-Darcy flow coefficient. Based upon the flowing cross sectional area of the gravel filled perforations, the non-Darcy coefficient was assumed to dominate the completion pressure drop. This coefficient was analyzed to yield the permeability of the gravel in the packed perforations connected to the fracture. This initial test and analysis showed that the permeability was much less than laboratory measured values. This damage was attributed to residual polymer damage. The well was monitored for one year. During this time, the gravel permeability increased. A multirate test and pressure buildup test were performed one year after treatment, and analysis showed that all damage to the gravel permeability had disappeared. The calculations used in these analyses are presented.
Slopes Analysis of Frac & Pack Bottomhole Treating Pressures
Authors: Valko P. , Oligney R. E. , Schraufnagel R. A. 
Published: July 2008

Abstract
A simple means has been developed to analyze frac & pack bottomhole treating pressures which gives insight to the fracture evolution and end-of-job proppant distribution. The method requires minimal input, is relatively model independent (as far as fracture propagation is concerned) and can be used in real time. This is not history matching, but rather an analysis or screening tool.
The key element of frac & pack treatments is the tip screen-out, a period of injection during which the fracture is inflated and the fracture extent remains relatively constant. The fracture may often extend in subsequent periods of regular fixed-area width growth with possible "jumps" and/or other irregular areal extension periods between them. The slope of the increasing pressure curve during a "regular" period may be interpreted to obtain the "packing radius" of the fracture, characteristic for the given period. The progression of packing radiuses can be combined with information on the proppant injection history to give final proppant distribution.
Controlling Organic Deposits and Sludge in a Severe Hostile Environment
Authors: Ftgueroa-Ortiz V. , Cazares-Robles F. , Fragachan F. E. 
Published: July 2008

Abstract
Formation damage, tubing plugging and plugged production equipment caused by the deposition of organic deposits and sludge are inherent in many workover and stimulation operations around the world.
This paper describes the methodology followed to improve production through adequate stimulation treatments and control of the organic and sludge deposition existing in the south-east of Mexico. In fact, this is a recurring problem that has existed for xnanv years severely affecting oil production.
Evaluation of the results and conclusions derived at different stages of the analysis are discussed. The benefits of emulsifying the acid with an aromatic (external phase), are also presented including the key factor of the iron reducing agent in a ferric iron environment in addition to the required iron sequestering agent.
Results of stimulations performed in the area are discussed including well performance months after treatments.
A Novel Reducing Agent for Combatting Iron-Induced Crude Oil Sludging: Development and Case Histories
Authors: Vinson Edward F. 
Published: July 2008

Abstract
This paper presents the results of a study of sludge formation from the reaction of "real-world" hydrochloric acid with several crude oils. Dissolved ferric iron has previously been shown to be a major factor in the genesis of sludges in acidizing treatments. This work compares the sludge abatement capabilities of a novel iron reducing agent with those of several iron control agents in common use in the oilfield. Simple tests based on established API procedures are used. Results of field treatments using the new reducing agent are included.
Postfracture Formation Evaluation in the Valhalla Field, Alberta
Authors: Ning X. , Collins J. L. , Marcinew R. P. , Dumont G. L. , Hogg J. R. 
Published: July 2008

Abstract
A number of highly permeable oil wells in the Valhalla field require re-fracturing treatments to optimize production. However, occasionally re-fracturing treatments are unsuccessful because the wells appear damaged after the treatments.
Presented are the results of an extensive study of the probable damage mechanism, and remediation of a well in the Valhalla field. A carefully designed and conducted pressure buildup test yielded better estimates of near wellbore and formation properties than the conventional test. A numerical reservoir simulator is used in the case study to history match the measured pressure buildup data and predict production. The cause and extent of the damage were determined, thus allowing modifications to be made to future re-fracturing programs. The well was then stimulated successfully with a second re-fracturing treatment.
The methodology presented in this study is designed to aid petroleum engineers to understand the importance of applying well-designed and interpreted pressure transient tests, to assess critical formation behavior.
Effect of Cleanup Acids on Compressive Strength of Proppants Used In Gravel Packing
Authors: Welch J. C. , Hossaini Mohammad 
Published: July 2008

Abstract
While originally developed for fracturing, manmade ceramic proppants are sometimes used for gravel packing wells. This is primarily due to their improved performance. However, the high solubility of ceramic proppants present in cleanup acids is a cause for concern when these proppants are used in gravel packing. This paper presents the results of a study investigating the effect of cleanup acids on the solubility and compressive strength of commercial gravel and ceramic proppants used in gravel packing.
A laboratory setup was designed to simulate material in a perforation tunnel. It included a Hassler core holder and lead sleeve mounts. Pre-flush, acid stages, and post-flush were pumped through the confined gravel and exposure time simulated field pumping times. Following acid exposure, the samples were checked for weight loss, submitted for SEM analysis, and tested for crush resistance. Fines and oversize particle generation were compared to untreated samples using standards set forth in API-RP 581.
It is possible that a perforation will plug during the acid stage. Since a plugged perforation would prevent a sweep by the postflush, gravel in the perforation would be exposed to live acid indefinitely. To gain insight into the effect of prolonged acid exposure, a sample of ceramic proppant and 12:3 mud acid + corrosion inhibitor was placed into a mud aging cell and heated for five days. Afterwards, the sample was checked for weight loss, submitted for SEM analysis, and tested for crush resistance.
Results of this study found that the effect of weight loss does not impact crush resistance when tested in accordance with the API-RP 58 gravel packing quality control procedure.
Effects of Completion Scenarios and Formation Damage on Two-Phase Inflow Performance of A Horizontal Well
Authors: Permadi Pudji 
Published: July 2008

AbstractCompletion scenarios and knowledge of formation damage distribution are key factors that determine the success of horizontal well applications. In a bottom water drive reservoir the completion scenario should be selective because a significant portion of the horizontal well section would not be productive at late production period. A simple correlation to estimate pseudoskin factors due to partial completion for a horizontal well is provided. When water or gas coning is not expected, distributed perforation intervals in a damaged formation yield the highest productivity.