bluuebunny/crossref_metadata_2025_split huggingface dataset:
"Volumetric" Reservoir Waters Out: Enhanced Aquifer Characterization Using PTA Derived Boundary Tracking
Authors: Khan Z. , Roopa I. , Baksh K. , Partap R , Mohammed S 
Published: June 2012

Abstract
The Mahogany field was discovered in 1968 and appraisal was completed in 1996. The field is located 50 miles offshore eastern Trinidad (Fig. 1) with the platforms situated in water depths of 230 feet and contains more than 30 stacked sands (17 of which are gas bearing) with a development footprint area of c. 10000 acres. Initially the field’s resources were booked assuming volumetric depletion was the dominant drive mechanism (Nandalal and Gunter 2003), however the updated understanding showed that water drive was the prevailing mechanism with near volumetric depletion being exhibited by only two reservoirs within the field, the TQ51 FB4 and TQ51 FB5.
There were two development wells in the TQ51 FB4, MA04 and MB13. MA04 became liquid loaded and stopped producing in March 2004 after fourteen months of concurrent production with MB13. MA04 showed volumetric behaviour until late life. Due to the volumetric response exhibited by the reservoir, the MB13 well was assigned low pressure access resources and was also used as a swing well to compensate for gas market demand fluctuations.
Conventional material balance techniques (P/Z, Havlena Odeh, van Everdingen Hurst aquifer match) led to the belief that the drive mechanism was volumetric to very weak aquifer support. Pressure Transient Analysis (PTA) and pore volume material balance estimates showed the presence of an edge drive aquifer. This was corroborated by geological studies which showed that although the two reservoirs had the same initial gas water contact (GWC), with production they became two separate compartments exhibiting different properties, the aquifer acting via an edge drive mechanism.
Artificial-Lift Operation Technologies of Low-Pressure Flooded Gas and Gas-Condensate Wells
Authors: Drozdov A. N. , Bulatov G. G. , Lapoukhov A. N. , Mamedov E. A. , Malyavko E. A. , Alekseev Y. L. 
Published: June 2012

Abstract
One of the main reasons, leading to the production decline of gas and gas-condensate wells is the accumulation of liquid fluid on the bottom of the well and formation of liquid blockage. Under certain conditions, bottom hole pressure drops, flow rate declines and gas velocity reduction becomes insufficient for the liquid lifting. Periodic gas purging of low-pressure wells practiced in Russia for water extraction, leads to the unproductive losses of hydrocarbons and forbids achieving stable operation. It leads to the retirement of wells out of the producing well stock, formation of dead zones with entrapped gas and, as the final result, to the waterflood hydrocarbon recovery drawdown. This problem can be solved by putting low-pressure flooded wells on pump, as international experience being indicative of its benefits.
Various engineering solutions based on the field tests of the techniques, mentioned above, were examined. The most suitable and viable technologies, for one of the Russian fields to be at the latest stage of reservoir development, were electric submersible centrifugal pumps (ESP) and electric progressive cavity pumps (ESPCP): with the removing of water to the surface and the subsequent injection of water into injection wells, and also with the injection of water into the underlying aquifer in the existing producing well.
We developed a rational method of hydraulic calculation and selection ESP and ESPCP for different operating conditions. Preliminary bench experiments of ESP’s, centrifugal gas separators and separator of mechanical impurities were carried out. The equipment has proven its efficiency.
The proposed solution will ensure the efficient functioning of the system of artificial-lift gas and gas-condensate well operation without using the unique expensive equipment. Also in a short period of time it could allow adapting the quantity produced submersible pumps for the conditions of gas industry.
Memory-Based Depth Control Technique -- Practical Application for Precise Deployment of Explosives on Slickline, Coiled Tubing And Drillpipe
Authors: Friedli J. , Charles N. 
Published: June 2012

Abstract
With the advent of intelligent memory based controllers for initiation of pyrotechnic passenger loads, there has been an expansion of the range of services available to operators via non-traditional conveyance. The primary concerns for non-real time initiation of pyrotechnics are safety and depth control. Modern memory based trigger devices include multiple fail safe routines within the fire command sequence and these are well documented in technical and commercial literature. This paper deals with the concepts and challenges of achieving reliable depth control.
The technique employed here applies to all non-conductive deployment systems, (slickline, conventional coiled tubing, and jointed pipe) and does not require specialized surface equipment other than standard depth encoders and memory correlation logging tools (typically Gamma Ray and or CCL). The technique relies on understanding the limitations and observing a few simple conventions. A reasonable analogy of the technique would be aviation under IFR (Instrument Flight Rules) versus VFR (Visual Flight Rules). Both methods are valid when the accepted methodology is respected.
This is an important development in the industry because it affords flexibility to operators where there are fiscal or logistical barriers to conventional, real time correlation. Some benefits:Reduce critical path rig operations by multi-tasking standard completion stepsMinimize rig up / rig down time by concentrating more tasks into a single deployment mediumPermit access to previously unrecoverable shut in reserves. Many platforms will accept no more than a small slickline unit. Wells that previously would require prohibitively expensive rig intervention can be re-completed using slickline.Taking advantage of these options, offshore facility designers can realize significant savings in fabrication.
The paper demonstrates that, when proper conventions are observed, the technique reliably deploys payloads with precision compatible to the full range of pyrotechnic completion and intervention services in the modern energy services market.
Re-Innovating Old Technology Improves Efficiency of Proven Coiled-Tubing Stimulation
Authors: Lindsay S. , Ables C. , Holden D. 
Published: June 2012

Abstract
Worldwide demand for energy has forced the energy services industry to increase process efficiency and create innovative new methods of fracture stimulation optimization. Pinpoint fracturing methods represent a divergence from conventional fracture stimulation methods, which provide minimal optimization to reservoir volume. Pinpoint fracturing methods allow multiple interval completions to be performed efficiently, helping ensure that all intervals receive the optimum fracture intensity.
To increase process efficiency, coiled tubing (CT) is used to hydra-jet perforate intervals for individual fracturing treatments at predetermined depths. The process uses a unique bottomhole assembly (BHA), which was recently redesigned to increase the efficiency of the hydra-jetting tool and isolate the fracture stimulation from previous intervals. This pinpoint fracturing method does not require removing the CT from the well between treatments. Risks of non-productive time (NPT) are mitigated because contingencies for early screenout avoidance can be initiated immediately during the fracture stimulation with minimal impact on overall completion costs. Treating intervals individually substantially helps reduce the amount of hydraulic horsepower required onsite, further reducing completion costs and the risk of NPT caused by down horsepower.
Re-innovating fracture stimulation technology is often a challenge. The new technology must add value and efficiency to the process, while remaining reliable and commercially viable. In this case, these requirements were met by reducing the complexity of the BHA while increasing hydra-jetting efficiency. The elimination of moving parts increased the process reliability and simplified operational procedures.
This paper examines the re-innovation of this older technology.
Unraveling the Performance Characteristics of the Most Mature Shallow Gas Reservoir in the Trinidad Acreage in the Columbus Basin
Authors: Roopa I. , Benjamin K. 
Published: June 2012

Abstract
The BP Trinidad gas fields are located in the Columbus basin, 35-40 miles off the southeast coast of Trinidad in water depths of between 200 to 300 feet. The fields are comprised of highly faulted stacked sandstone reservoir units of varying ages between Quaternary to Pleistocene. Most reservoir units contain original gas in place of less than 0.5 tcf and are usually produced by one or two wells. The shallow gas reservoirs (&lt; 4500 ft TVDSS) constitute a significant percentage of the non-producing BP Trinidad gas portfolio. Reservoir data, such as rock compressibility, and performance data such as recovery factors are lacking in both the local and global database for analogous reservoirs at these depths.
Initially these shallow gas reservoirs were considered as drilling hazards for deeper reservoirs therefore well paths and platform locations avoided them as recovery from them were initially expected to be very poor. The shallowest producing reservoir unit to date is from the TP95 reservoir in the Greater Cassia Field Complex and it has one producer. This reservoir depth is 4200ft TVDSS and it has been on production since 2003, exceeding expectations with its recovery. This paper investigates the key uncertainties associated with this reservoir including depth conversion (since it is overlain by other shallow gas reservoirs), rock compressibility and aquifer support. It also shows the well and reservoir performance data, key surveillance data collected as well as types of analysis and modeling performed to help understand and predict the reservoir performance given the aforementioned subsurface uncertainties.
Effect of Gas Cap and Aquifer Strength on Optimal Well Location for Thin-Oil Rim Reservoirs
Authors: Iyare U. C. , Marcelle-De Silva J. 
Published: June 2012

Abstract
Many hydrocarbon reservoirs have an oil bearing zone, sandwiched between gas and water bearing zones. For these reservoirs, considerable studies are conducted to optimize the location of wells in the oil rim so as to maximize oil recovery. Few studies however have investigated the conditions under which wells could be located in either the gas cap or the water leg so as to also maximize oil recovery.
This study investigates the effect of gas cap and aquifer sizes on oil recovery from a reservoir with a thin oil rim using a single well numerical reservoir simulator model. Sensitivity studies were conducted by varying gas cap size, aquifer size and well location, and analyzing their effect on oil recovery.
The results indicated that for a reservoir with a large gas cap, it may be more favorable to place the horizontal well below the water-oil contact; for a reservoir with a small gas cap and large aquifer, it may be advantageous to place the horizontal well above the gas-oil contact.
This study is significant since thin oil rims are especially prominent in the prolific gas province offshore the east coast of Trinidad, and maximizing oil recovery, the more valuable resource, has positive financial implications.
New Metrics for Assessing Diagnostic Potential of Candidate Biomarkers
Authors: Pickering John W. , Endre Zoltan H. 
Published: June 2012

Summary
New tests should improve the diagnostic performance of available tests. The area under the receiver operator characteristic curve has been the “metric of choice” to quantify new biomarker performance. Two new metrics, the integrated discrimination improvement (IDI) and net reclassification improvement (NRI), have been rapidly adopted to quantify the added value of a biomarker to an existing test. These metrics require the development of risk prediction models that calculate the probability of an event for each individual. This study demonstrates the application of these metrics in 528 critically ill patients with risk models of AKI, sepsis, and 30-day mortality to which the biomarker urinary cystatin C was added. Analogous to the receiver operator characteristic curve, we present a new risk assessment plot for visualizing these metrics. The results showed that the NRI was sensitive to the choice of risk threshold. The risk assessment plot identified that the addition of urinary cystatin C to the model decreased the calculated risk for some who did not have sepsis but increased it for others. The category-free NRI for each outcome indicated that most of those without the event had reduced calculated risk. This was driven by very small changes in calculated risk in the AKI and death models. The IDI reflected those small changes. Of the new metrics, the IDI, reported separately for those with and without the events, best represents the value of a new test. The risk assessment plot identified differences in the models not apparent in any of the metrics.
Is the BESTest at Its Best? A Suggested Brief Version Based on Interrater Reliability, Validity, Internal Consistency, and Theoretical Construct
Authors: Padgett Parminder K. , Jacobs Jesse V. , Kasser Susan L. 
Published: June 2012

BackgroundThe Balance Evaluation Systems Test (BESTest) and Mini-BESTest are clinical examinations of balance impairment, but the tests are lengthy and the Mini-BESTest is theoretically inconsistent with the BESTest.ObjectiveThe purpose of this study was to generate an alternative version of the BESTest that is valid, reliable, time efficient, and founded upon the same theoretical underpinnings as the original test.DesignThis was a cross-sectional study.MethodsThree raters evaluated 20 people with and without a neurological diagnosis. Test items with the highest item-section correlations defined the new Brief-BESTest. The validity of the BESTest, the Mini-BESTest, and the new Brief-BESTest to identify people with or without a neurological diagnosis was compared. Interrater reliability of the test versions was evaluated by intraclass correlation coefficients. Validity was further investigated by determining the ability of each version of the examination to identify the fall status of a second cohort of 26 people with and without multiple sclerosis.ResultsItems of hip abductor strength, functional reach, one-leg stance, lateral push-and-release, standing on foam with eyes closed, and the Timed “Up & Go” Test defined the Brief-BESTest. Intraclass correlation coefficients for all examination versions were greater than .98. The accuracy of identifying people from the first cohort with or without a neurological diagnosis was 78% for the BESTest versus 72% for the Mini-BESTest or Brief-BESTest. The sensitivity to fallers from the second cohort was 100% for the Brief-BESTest, 71% for the Mini-BESTest, and 86% for the BESTest, and all versions exhibited specificity of 95% to 100% to identify nonfallers.LimitationsFurther testing is needed to improve the generalizability of findings.ConclusionsAlthough preliminary, the Brief-BESTest demonstrated reliability comparable to that of the Mini-BESTest and potentially superior sensitivity while requiring half the items of the Mini-BESTest and representing all theoretically based sections of the original BESTest.
A thrombosing, giant, distal posterior cerebral artery aneurysm in a newborn infant
Authors: Sabanci Pulat Akın , Aras Yavuz , Aydoseli Aydın , Sencer Serra , Sencer Altay , Erguven Mine , Izgi Nail 
Published: June 2012

Intracranial aneurysms are extremely rare in infancy. No consensus has yet been developed about the exact treatment of this rare situation. The authors report the case of a 47-day-old male infant who had multiple seizures on the same day, leading to the diagnosis of an intracranial aneurysm. The case was managed conservatively with close imaging follow-up, and the patient had a good recovery. The results of neurological examination were completely normal at the 5-year follow-up visit.
These rare lesions may be suspected on the basis of clinical findings and correctly diagnosed with current neuroradiological imaging modalities. The authors believe this report contributes valuable imaging data on rare childhood aneurysms to the literature, as well as emphasizing the importance of clinical and imaging information in therapeutic decision making in children with intracranial vascular problems.
Complete remission of seizures after corpus callosotomy
Authors: Iwasaki Masaki , Uematsu Mitsugu , Sato Yuko , Nakayama Tojo , Haginoya Kazuhiro , Osawa Shin-ichiro , Itabashi Hisashi , Jin Kazutaka , Nakasato Nobukazu , Tominaga Teiji 
Published: June 2012

Object
Corpus callosotomy is usually intended to alleviate—not to achieve total control of—epileptic seizures. A few patients experience complete seizure control after callosotomy, but the associated clinical factors are unknown. The object of this study was to investigate clinical factors associated with long-term seizure remission after total corpus callosotomy in patients with infantile or early childhood onset epilepsy.

Methods
Thirteen consecutive patients with infantile or early childhood onset epilepsy underwent 1-stage total corpus callosotomy for alleviation of seizures. Their age at surgery ranged from 1 year and 5 months to 24 years (median 7 years). Eleven patients had West syndrome at the onset of disease, and the other 2 had Lennox-Gastaut syndrome. All patients suffered from spasms, axial tonic seizures, or atonic seizures. Six patients had proven etiology of epilepsy, including tuberous sclerosis, polymicrogyria, trauma, and Smith-Magenis syndrome. The association between postoperative seizure freedom and preoperative factors including age at surgery, no MRI abnormalities, proven etiology, and focal electroencephalographic epileptiform discharges was examined.

Results
Postoperative seizure freedom was achieved in 4 of 13 patients for a minimum of 12 months. All 4 patients had no MRI abnormalities and no identified etiology. None of the 8 patients with MRI abnormality, 6 patients with known etiology of epilepsy, or 4 patients aged older than 10 years at surgery achieved seizure freedom. Two of the 7 patients with focal electroencephalographic abnormalities became seizure free. Absence of MRI abnormalities was significantly associated with postoperative seizure freedom (p < 0.01).

Conclusions
Complete seizure remission is achieved after total corpus callosotomy in a subgroup of patients with intractable epilepsy following West syndrome or Lennox-Gastaut syndrome. One-stage total corpus callosotomy at a young age may provide a higher rate of seizure freedom, especially for patients with no MRI abnormalities and no identified etiology of epilepsy.
Multimodality localization of the sensorimotor cortex in pediatric patients undergoing epilepsy surgery
Authors: Wray Carter D. , Blakely Tim M. , Poliachik Sandra L. , Poliakov Andrew , McDaniel Sharon S. , Novotny Edward J. , Miller Kai J. , Ojemann Jeffrey G. 
Published: June 2012

Object
The gold-standard method for determining cortical functional organization in the context of neurosurgical intervention is electrical cortical stimulation (ECS), which disrupts normal cortical function to evoke movement. This technique is imprecise, however, as motor responses are not limited to the precentral gyrus. Electrical cortical stimulation also can trigger seizures, is not always tolerated, and is often unsuccessful, especially in children. Alternatively, endogenous motor and sensory signals can be mapped by somatosensory evoked potentials (SSEPs), functional MRI (fMRI), and electrocorticography of high gamma (70–150 Hz) signal power, which reflect normal cortical function. The authors evaluated whether these 4 modalities of mapping sensorimotor function in children produce concurrent results.

Methods
The authors retrospectively examined the charts of all patients who underwent epilepsy surgery at Seattle Children's Hospital between July 20, 1999, and July 1, 2011, and they included all patients in whom the primary motor or somatosensory cortex was localized via 2 or more of the following tests: ECS, SSEP, fMRI, or high gamma electrocorticography (hgECoG).

Results
Inclusion criteria were met by 50 patients, whose mean age at operation was 10.6 years. The youngest patient who underwent hgECoG mapping was 2 years and 10 months old, which is younger than any patient reported on in the literature. The authors localized the putative sensorimotor cortex most often with hgECoG, followed by SSEP and fMRI; ECS was most likely to fail to localize the sensorimotor cortex.

Conclusions
Electrical cortical stimulation, SSEP, fMRI, and hgECoG generally produced concordant localization of motor and sensory function in children. When attempting to localize the sensorimotor cortex in children, hgECoG was more likely to produce results, was faster, safer, and did not require cooperation. The hgECoG maps in pediatric patients are similar to those in adult patients published in the literature. The sensorimotor cortex can be mapped by hgECoG and fMRI in children younger than 3 years old to localize cortical function.
Elevated diffusion anisotropy in gray matter and the degree of brain compression
Authors: Osuka Satoru , Matsushita Akira , Ishikawa Eiichi , Saotome Kousaku , Yamamoto Tetsuya , Marushima Aiki , Satou Naoaki , Zaboronok Alexander , Masumoto Tomohiko , Matsumura Akira 
Published: June 2012

Object
For several decades, clinicians have predicted intraparenchymal brain pressure or brain tissue compression indirectly based on the degree of distortion of the midline structures (midline shift) and ventricle wall (ventriculomegaly) observed on conventional MRI. However, this method has several limitations. Diffusion tensor imaging (DTI) is a novel MRI technique that can provide information about the microstructural properties of compressed tissue. In this study, the authors evaluated whether DTI can precisely define the degree of tissue compression in patients with chronic subdural hematoma (CSDH).

Methods
The study sample consisted of 18 patients (mean age 71 years, 10 men and 8 women) with unilateral CSDH and 12 age-matched volunteers. Diffusion tensor imaging results were acquired before and after the surgical irrigation in the CSDH group. Subdural pressure during the operation was also measured. Fractional anisotropy (FA) values were evaluated at several locations, including the gray matter.

Results
The FA values of the gray matter, especially in the caudate nucleus and putamen, were increased in the patients with CSDH compared with the control group. The change in FA data before and after surgery (ΔFA) correlated with the degree of tissue compression evaluated by measurement of the subdural pressure. Furthermore, the increased FA values in patients with CSDH decreased after surgery.

Conclusions
These findings indicate that FA values of the gray matter, especially in the caudate nucleus and putamen, may be important markers of tissue compression. The assessment of FA values of the gray matter will result in a new, less-invasive diagnostic technique to evaluate the degree of brain compression.