bluuebunny/crossref_metadata_2025 huggingface dataset:
Lysophosphatidic acid as a potential target for treatment and molecular diagnosis of epithelial ovarian cancers
Authors: Tanyi János , Rigó Jr. János
Published: May 2009

Az ováriumtumorok mortalitása a legmagasabb a nőgyógyászati tumorok között. Ez egyrészt a késői diagnózisnak, másrészt a hatásos terápia hiányának következménye. Az ováriumtumorok karcinogenezise és metasztázisképzése egy komplikált genetikai, molekuláris és biokémiai folyamatsor eredménye. A lizofoszfátsav (LPA) termelésének, receptorstátusának és szignáltranszdukciós útvonalának abnormalitása gyakran megtalálható az ováriumtumorokban, ami azt sejteti, hogy az LPA nagyon fontos szerepet játszik ennek a betegségnek a kialakulásában és patofiziológiájában. Így jogosan feltételezhetjük, hogy az LPA-szignálkaszkád számos célpontot szolgáltat a molekuláris kezelési módok kialakítására és jó példát mutat arra, hogyan lehet új diagnosztikus és terápiás módszereket kialakítani egyes betegségek ellen. Az LPA-t lebontó és termelő enzimcsaládoknak csak a közelmúltban történt felfedezése és a receptorspecifikus molekulák kifejlesztése új fejezetet nyithat e potenciálisan halálos betegség kezelésében. Ebben az összefoglaló tanulmányban ismertetjük, hogy a tumorsejtekben lévő LPA-t lebontó enzimek aktivitása csökkent, és ez hozzájárul a tumor progressziójához. Ugyanezen enzimek mesterségesen létrehozott, fokozott aktivitása csökkenti a tumorsejtek növekedését és elősegíti a fiziológiás viszonyok helyreállását. Bemutatjuk azokat az irodalmi adatokat, amelyek egyértelműen bizonyítják, hogy a lipidfoszfát-foszfatáz enzimek hatásukat a sejten kívüli LPA lebontásával érik el. Minthogy ez a lebontás extracellulárisan történik, ez megmagyarázza a „bystander-effect” előfordulását, amit szintén ismertetünk. Az LPA-lebontás és -termelés enzimjei, illetve az LPA-t kötő receptorok kitűnő célpontok új molekuláris terápia kidolgozására. A különböző LPA-izoformák és más lizofoszfolipidek szintváltozásainak korai detektálása segíthet a tumor korai diagnosztizálásában, illetve később a kezelés hatékonyságának követésében. A közelmúlt jelentős LPA-szignálkaszkáddal kapcsolatos kutatási eredményei azt sejtetik, hogy azok jelentős szerepet fognak játszani ennek a még mindig halálos betegségnek a kezelésében, de további kutatások szükségesek a részletek pontos megértéséhez.
MTA family of coregulators in nuclear receptor biology and pathology
Authors: Manavathi Bramanandam , Singh Kamini , Kumar Rakesh
Published: June 2009

Nuclear receptors (NRs) rely on coregulators (coactivators and corepressors) to modulate the transcription of target genes. By interacting with nucleosome remodeling complexes, NR coactivators potentiate transcription, whereas corepressors inhibit transcription of the target genes. Metastasis-associated proteins (MTA) represent an emerging family of novel NR coregulators. In general, MTA family members form independent nucleosome remodeling and deacetylation (NuRD) complexes and repress the transcription of different genes by recruiting histone deacetylases onto their target genes. However, MTA1 also acts as a coactivator in a promoter-context dependent manner. Recent findings that repression of estrogen receptor transactivation functions by MTA1, MTA1s, and MTA2 and regulation of MTA3 by estrogen signaling have indicated the significance of these proteins in NR signaling. Here, we highlight the action of MTA proteins on NR signaling and their roles in pathophysiological conditions.
A Global View of Transcriptional Regulation by Nuclear Receptors: Gene Expression, Factor Localization, and DNA Sequence Analysis
Authors: Kininis Miltiadis , Kraus W. Lee
Published: June 2009

Recent genomic analyses of transcription factor binding, histone modification, and gene expression have provided a global view of transcriptional regulation by nuclear receptors (NRs) that complements an existing large body of literature on gene-specific studies. The picture emerging from these genomic studies indicates that NRs bind at promoter-proximal and promoter-distal enhancers in conjunction with other transcription factors (e.g., activator protein-1, Sp1 and FOXA1). This binding promotes the recruitment of coregulators that mediate the posttranslational modification of histones at promoters and enhancers. Ultimately, signaling through liganded NRs stimulates changes in the occupancy of RNA polymerase II (Pol II) or the activation of preloaded Pol II at target promoters. Chromosomal looping and/or Pol II tracking may underlie promoter-enhancer communication. Interestingly, the direct target genes of NR signaling represent a limited subset of all the genes regulated by NR ligands, with the rest being regulated through secondary effects. As suggested by previous gene-specific analyses, NR-mediated outcomes are highly cell type- and promoter-specific, highlighting the complexity of transcriptional regulation by NRs and the value of genomic analyses for identifying commonly shared patterns. Overall, NRs share common themes in their patterns of localization and transcriptional regulation across mammalian genomes. In this review, we provide an overview of recent advances in the understanding of NR-mediated transcription garnered from genomic analyses of gene expression, factor localization, and target DNA sequences.
Prognostic Factors in Patients with Ovarian Serous Low Malignant Potential (Borderline) Tumors with Peritoneal Implants
Authors: Kane Aminata , Uzan Catherine , Rey Annie , Gouy Sebastien , Camatte Sophie , Pautier Patricia , Lhommé Catherine , Haie-Meder Christrine , Duvillard Pierre , Morice Philippe
Published: June 2009

Background.

The objective of this study was to determine prognostic factors in a large series of patients with stage II or III serous low malignant potential ovarian tumor (LMPOT) and peritoneal implants.

Methods.

Patients with a serous LMPOT and peritoneal implants treated at or referred to our institution were retrospectively reviewed. The slides of ovarian tumors and peritoneal implants were reviewed by the same pathologist.

Results.

From 1969 to 2006, 168 patients were reviewed, 21 of whom had invasive implants. Tumors exhibited a micropapillary pattern in 56 patients. Adjuvant treatment had been administered to 61 patients. The median duration of follow-up was 57 months (range, 1–437). Forty-four patients had relapsed and 10 patients had died. The 5-year overall survival rate was 98%. Among patients with noninvasive and invasive implants, 8% and 10%, respectively, had relapsed at 5 years in the form of invasive disease (p = .08). In a multivariate analysis, the use of conservative treatment was the only prognostic factor.

Interpretation.

The prognosis of serous LMPOT with peritoneal implants remains good. The strongest prognostic factor in patients with an advanced-stage borderline tumor is the use of conservative surgery. In this series, a micropapillary pattern and implant subtype (invasive versus noninvasive) were not prognostic factors.
Systemic Immune Responses in Pregnancy and Periodontitis: Relationship to Pregnancy Outcomes in the Obstetrics and Periodontal Therapy (OPT) Study
Authors: Ebersole Jeffrey L. , Novak M. John , Michalowicz Bryan S. , Hodges James S. , Steffen Michelle J. , Ferguson James E. , DiAngelis Anthony , Buchanan William , Mitchell Dennis A. , Papapanou Panos N.
Published: June 2009

Background: Our previous studies reported on the obstetric, periodontal, and microbiologic outcomes of women participating in the Obstetrics and Periodontal Therapy (OPT) Study. This article describes the systemic antibody responses to selected periodontal bacteria in the same patients.

Methods: Serum samples, obtained from pregnant women at baseline (13 to 16 weeks; 6 days of gestation) and 29 to 32 weeks, were analyzed by enzyme‐linked immunosorbent assay for serum immunoglobulin G (IgG) antibody to Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia (previously T. forsythensis), and Treponema denticola.

Results: At baseline, women who delivered live preterm infants had significantly lower total serum levels of IgG antibody to the panel of periodontal pathogens (P = 0.0018), to P. gingivalis (P = 0.0013), and to F. nucleatum (P = 0.0200) than women who delivered at term. These differences were not significant at 29 to 32 weeks. Changes in IgG levels between baseline and 29 to 32 weeks were not associated with preterm birth when adjusted for treatment group, clinical center, race, or age. In addition, delivery of low birth weight infants was not associated with levels of antibody at baseline or with antibody changes during pregnancy.

Conclusions: Live preterm birth is associated with decreased levels of IgG antibody to periodontal pathogens in women with periodontitis when assessed during the second trimester. Changes in IgG antibody during pregnancy are not associated with birth outcomes.
Periodontal Treatment Needs and Prevalence of Localized Aggressive Periodontitis in a Young Turkish Population
Authors: Ereş Gülden , Sarıbay Aysel , Akkaya Murat
Published: June 2009

Background: The purpose of this study was to investigate the prevalence of localized aggressive periodontitis (LAgP) among students aged 13 to 19 years at public schools in Ankara.

Methods: A total of 3,056 students (1,563 females and 1,493 males) participated in the study. All students were examined at their schools and their mouths coded according to the recommendations of the Community Periodontal Index of Treatment Needs (CPITN) using a mirror, a World Health Organization 621 ball‐tip probe, and daylight for illumination. Among the students examined, 170 had two or more sextants or teeth with code 3 or one sextant with code 4 and were scheduled for radiographs and a full clinical examination. The additional criteria for the diagnosis of LAgP were good general health, radiographically determined bone loss around the first molars bilaterally, and the bone loss must be unproportionally extensive with respect to the low levels of plaque and calculus, contrary to what is usually observed in chronic periodontitis.

Results: Among the 3,056 students screened, 170 were scheduled for further examination, and 18 (10 females and eight males) were diagnosed with LAgP. Of 18,336 sextants examined, 6,575 required scaling, and 63 required scaling and further complex treatment.

Conclusion: The prevalence of LAgP was 0.6%, with a female/male ratio of 1.25:1.
The Efficacy of Acetaminophen–Caffeine Compared to Ibuprofen in the Control of Postoperative Pain After Periodontal Surgery: A Crossover Pilot Study
Authors: Rashwan Weam A.M.
Published: June 2009

Background: Previous studies showed that non‐steroidal anti‐inflammatory drugs (NSAIDs) have significant benefits in the control of pain after periodontal surgery. Acetaminophen (centrally acting NSAID) is believed to provide less analgesic efficacy than ibuprofen (centrally and peripherally acting NSAID). This study compared an alternative combination of acetaminophen, 500 mg, with caffeine, 30 mg, to ibuprofen, 400 mg, in pain management after periodontal surgeries.

Methods: A prospective, randomized, double‐masked crossover clinical trial was conducted on 15 patients. Open flap debridement was performed on two quadrants with a 3‐week interval in between. Each quadrant was randomly assigned to acetaminophen, 500 mg, with caffeine, 30 mg, or ibuprofen, 400 mg, immediately after surgery and 8 hours after the first dose. Postoperative pain was assessed during the first 8 hours and on the following day using the 101‐point numeric rate scale (NRS‐101) and the four‐point verbal rating scale (VRS‐4).

Results: Using the NRS‐101, the acetaminophen‐caffeine group showed statistically significantly lower mean pain scores than the ibuprofen group at 1 and 2 hours (P = 0.002), whereas at 6, 7, and 8 hours, the ibuprofen group showed statistically significantly lower mean pain scores (P <0.001). Using the VRS‐4, there was no statistically significant difference between the two groups at all periods (P >0.05).

Conclusion: Acetaminophen, 500 mg, with caffeine, 30 mg, can be used efficiently in controlling postoperative pain after open flap debridement, especially in patients with gastric ulcers or bleeding tendency because acetaminophen is less hazardous than ibuprofen.
In Vitro Evaluation of the Effects of Low‐Intensity Nd:YAG Laser Irradiation on the Inflammatory Reaction Elicited by Bacterial Lipopolysaccharide Adherent to Titanium Dental Implants
Authors: Giannelli Marco , Bani Daniele , Tani Alessia , Pini Alessandro , Margheri Martina , Zecchi‐Orlandini Sandra , Tonelli Paolo , Formigli Lucia
Published: June 2009

Background:The bacterial endotoxin lipopolysaccharide (LPS) represents a prime pathogenic factor of peri‐implantitis because of its ability to adhere tenaciously to dental titanium implants. Despite this, the current therapeutic approach to this disease remains based mainly on bacterial decontamination, paying little attention to the neutralization of bioactive bacterial products. The purpose of the present study was to evaluate whether irradiation with low‐energy neodymium‐doped:yttrium, aluminum, and garnet (Nd:YAG) laser, in addition to the effects on bacterial implant decontamination, was capable of attenuating the LPS‐induced inflammatory response.

Methods:RAW 264.7 macrophages or human umbilical vein endothelial cells were cultured on titanium disks coated withPorphyromonas gingivalisLPS, subjected or not to irradiation with the Nd:YAG laser, and examined for the production of inflammatory cytokines and the expression of morphologic and molecular markers of cell activation.

Results:Laser irradiation of LPS‐coated titanium disks significantly reduced LPS‐induced nitric oxide production and cell activation by the macrophages and strongly attenuated intercellular adhesion molecule‐1 and vascular cell adhesion molecule expression, as well as interleukin‐8 production by the endothelial cells.

Conclusion:By blunting the LPS‐induced inflammatory response, Nd:YAG laser irradiation may be viewed as a promising tool for the therapeutic management of peri‐implantitis.
A Fractal Model of Production by Spontaneous Water Imbibition
Authors: Zhao Haiyang , Li Kewen
Published: May 2009

A mathematical model was proposed to predict production in rock by spontaneous imbibition. Heterogeneity of rock represented by fractal dimension was considered. This fractal model predicts a power law relationship between spontaneous imbibition rate and time. Experimental data of recovery in gas-water-rock and oil-water-rock systems were used to test the fractal model. Spontaneous water imbibition experiments were conducted in different type of rocks (Berea sandstone, chalk, and The Geysers gray wacke) with permeability ranging from 0.5 to over 1000 md. The results demonstrated that the fractal production model could match the experimental data satisfactorily in the cases studied. The fractal dimension data inferred from the model match were approximately equal to the values of fractal dimension obtained using a different technique (mercury-intrusion capillary pressure) in Berea sandstone.
Complex Well Modeling Workflow Enabling Full Field Optimization and Forward Decisions
Authors: Al-Qahtani Ghazi D. , Elrafie Emad A. , Abbas Raja T. , Ikuku Clara E. , Hogg Martin F. , Rincon Alexander
Published: May 2009

The application of Complex Wells (CW) as a component of an optimized field development strategy at single well, sector model and or small scale multi-well level is generally well understood. In contrast, the application, modeling and optimization of a full field strategy inclusive of CW remains a daunting industry challenge.

This paper describes a highly successful four-step workflow to manage, assess and model the qualification of a CW optimization strategy at a full field model scale. The paper utilizes a field case to illuminate a CW field wide optimization – extended production plateau, increased production rates and CW completion strategies – approach as compared to single, sector and or multi-well level CW model derived field development decisions. In this paper, complex wells include; Multi-laterals (ML) and Maximum Reservoir Contact wells (MRC) inclusive of down-hole Internal Control Devices (ICD), Equalizers (ICD or equalizers) and or Internal Control Valves (ICV).

The workflow starts with reservoir understanding and identifying the need for CW. A sector model is then extracted from the full field model to conduct detailed well level analysis. This is followed by defining well sensitivity cases, that may include a range of field development decision scenarios and a resultant optimization strategy that recommends a combined conventional and CW field optimization approach. From sensitivity cases, the best fit well(s) case scenario is identified. Thereafter, the optimized well(s) strategy is applied to the full field model and evaluated under uncertainty. Detailed analysis is conducted on both the sector and full field models including well location, orientation, placement, length, and target zones for various CW configurations.

The resultant development strategy is an optimized full field CW development decision approach including for example; improved sweep efficiency, delayed water breakthrough, improved oil recovery, reduced water handling expense, reduced produced water, extended oil plateau duration and reduced environmental impact.
Waterflood Recovery Optimization Using Intelligent Wells and Decision Analysis
Authors: Saputelli L. , Ramirez K. , Chegin J. , Cullick S.
Published: May 2009

The many critical decisions in a waterflood recovery process range from well number, architecture, and completion configuration to scheduling and facilities capacity planning. Project success is also affected by subsurface uncertainties, such as reservoir heterogeneity and compartmentalization, as well as surface events including equipment uptime and availability. Managing the complexities of a waterflood recovery is traditionally a sequential and intermittent process in terms of data acquisition, modeling, and workflows. However, traditional project planning, execution, and monitoring may help an operator reach production targets and budgets, but these activities do not necessarily align technical and business goals to create a comprehensive development plan that increases the probability of optimal business success.

This paper describes a process to maximize long-term economic return by optimizing key decisions, such as well number, placement, and use of intelligent wells and operating schedules, as well as evaluating surface capacity parameters, such as export pipeline diameter and pump inlet pressure. An integrated asset model (IAM) simultaneously simulates the reservoir flow, wells, and facilities, and calculates the economics associated with each potential decision scenario. An automated optimization workflow is presented as an efficient procedure to handle a large number of decisions. A well-known industry waterflood case study is discussed in the paper. A development plan that includes processes for maximizing oil recovery and economic return by implementing intelligent-well operational procedures is presented.

The results from this work for the case examples presented show that the number and location of the wells are more significant factors in the success of the field development plan than the selection of export pipeline diameter or pump inlet pressure. The optimum selection of well number, location, and producer to injector ratio could lead to an increase of 136%, when compared to the optimized primary recovery case. In the secondary recovery example, a proactive operating scheduling of intelligent well valves improved the waterflood project value by 130% with respect to the case with no intelligent completion; this was achieved by the efficient reduction in produced (~9%) and injected (~8%) water, and the increase of produced oil (~3%).

Applications of this workflow and integration by professionals from multiple surface and subsurface disciplines provide a means of minimizing the risk of investment and setting optimal surface parameters that maximize production while reducing capital and operating costs. In this way, the return on investment of the project is optimized. The decision framework presented may be applied in any type of hydrocarbon field, from early to mature development, and may be extended to other important decision variables, including the selection of the reservoir recovery process and market strategy.
First Deepwater Well Successfully Drilled in Colombia with a High-Performance Water-Based Fluid
Authors: Marin J. , Shah F. , Serrano M. , Jaramillo A. , Marin C. , Arevalo W. , Priandi G.
Published: May 2009

Deepwater drilling presents significant issues and uncertainties, especially when there is no prior drilling experience in country or only limited offset information is available. Uncertainties about the drilling conditions create additional risk to operators and can cause project budget increases. Therefore, innovative technologies are often implemented to help ensure that the well is drilled efficiently and safely, operators obtain well data and important geological data that can help identify potential reservoirs and wells in the area. Petrobras Colombia undertook the challenge of drilling the first deepwater well in Tayrona BLock located in the Colombian Caribbean, in approximately 1,840 ft water depth. Drilling fluid selection was a key decision to the success of the project due to the nature of the exploratory project, formation uncertainty, environmental footprint, wellbore stability and protecting any potential reservoirs.

A high-performance water-based fluid (HPWBF) was selected to drill the well based on the following criteria; The ability to discharge to the sea without environmental impactEffective inhibition capability to drill reactive clay formationsNon-dispersed, low-solids formulation to improve rate of penetration (ROP)Shear-thinning behavior for excellent hole cleaningHigh and low temperature as well as high-pressure stabilityLubricity, wellbore stability and low equivalent circulating density (ECD) values.

The HPWBF provided excellent performance as demonstrated by trouble-free trips, casing, cementing and wireline logging operations. Rheological properties remained stable during changes in temperature and pressure, confirming reliable fluid stability and reducing costs associated with non productive time (NPT).

Although the inhibition provided by the fluid system was excellent, the wellbore exhibited some mechanical instability related to stress distribution. No bit balling problems were observed and ROP was acceptable most of the time. Wiper trips required less time than expected and did not present any issues. In conclusion, the HPWBF demonstrated excellent performance in all aspects and contributed to the overall project success in obtaining important formation data, minimizing NPT and reducing costs related to fluid and cuttings disposal.
New Correlations for Critical and Subcritical Two-Phase Flow through Surface Chokes in High-Rate Oil Wells
Authors: Al-Attar Hazim H.
Published: May 2009

The critical and subcritical multiphase flow through wellhead restrictions of a prolific oil field in the Middle East is investigated and two sets of new correlations are presented. The first set of correlations is developed by using "40" field tests representing critical flow conditions. The second set of correlations is based on "139" field tests representing subcritical flow conditions of gas-liquid mixtures through wellhead chokes.

For the critical multiphase flow condition, the predicted oil flow rates by the new set of correlations are in excellent agreement with the measured ones. The absolute average percent difference (AAPD) is between "1.88" and "4.37", and the corresponding standard of deviation (SD) is between "2.52" and "6.52". These results are found to be statistically superior to those predicted by other published correlations considered in this work. During the subcritical gas-liquid flow conditions through surface chokes, the accuracy of oil flow rates predicted by the new set of correlations seems to be sensitive to the type and size of the choke being used. For Cameron LD type and 144/64th -inch choke, the oil flow rates predicted by the proposed correlation are superior to those predicted by other methods available in the literature, with AAPD of "8.5". However, for smaller choke sizes of 96/64th and 64/64th -inch, the oil flow rates predicted by the new correlations and other methods are found to be close to each other. For Cameron F type and 144/64th -inch choke size, the oil flow rates predicted by the new correlation are closely matched by those predicted by other published methods, with AAPD of "13.7". For smaller choke sizes of 80/64th and 64/64th -inch few field tests are available and the predications of all methods, including the proposed ones, show similar statistical results. The above findings for Cameron F choke also seem to apply to Beaned wellhead assemblies for this particular oil field.
Feasibility Study of Dual "Backup" Electrical Submersible Pump Based on Risk Analysis
Authors: Pérez Aileen , Caicedo Sergio
Published: May 2009

Electric Submersible Pumping is one of the predominant lift methods used in Barua-Motatán field of Tomoporo district, Venezuela. Each year the increasing number of ESP failures has become in a crucial issue for the Venezuelan oil company (Petróleos de Venezuela – PDVSA) due to the adversely effecting on lifting costs, rig utility and production. A dual ESP (dESP) completion in which the second pump is used as a backup is proposed in this study as an alternative for optimizing production, increasing ESP run life, reducing unscheduled deferments and minimizing ESP related well services and associated costs.

A critical techno – economics analysis of different proposal from local ESP vendors showed that the suitable option due to space restrictions (casing 7-5/8 in.) is a pod type completion in which primary and backup ESPs are in serial. A risk assessment confirmed the feasibility of the application of dESP in Tomoporo district. The Net Present Value (NPV) of using the new scheme completion proposed is always greater that the conventional single ESP scheme. The high initial capital expenditure incurred from the use of the technology is offset by the significant increase in the profit margin related to the decrease in operational cost and steady production. The most important and unexpected achievement was that probabilities of having negative NPV are reduced considerably with dESP as could be confirmed by risk analysis. Finally, dESP application simplifies drilling scheduling which enhances the planning of well interventions.
Viscosity Effect in Cyclone Separators
Authors: Brito A. , Trujillo J.
Published: May 2009

The gas liquid cyclone separator is a device that works as a result of the centrifugal force acting on the denser phase of a two-phase flow. This causes the liquid phase which is denser than the gas, to move outward to the cyclone wall. The separated gas comes out by the top, the crude/water blend comes out by the bottom as a two phase stream. The separation time is almost instantaneous and due to its simple design, no moving parts and low cost, the cyclone separators have become an attractive solution for the new oil an gas field developments.

The liquid viscosity has a predominant influence in the performance of this kind of separators. As the liquid viscosity increases the shear stresses increase too producing a higher dissipation of the vortex intensity and as a consequence the separation efficiency is diminished. Therefore, the cyclone operational envelope for heavy oils is reduced as compared to light oils.

This paper presents the status of the gas-liquid cyclones separation studies related to their performance when used with high viscosity liquids. Experimental and computational studies from different sources, including PDVSA Intevep, are presented for different types of cyclones, with liquid viscosity between 1 and 1500 cP.
Jusepin Main Station Separation Facilities Upgrade by Means of Integrated Multiphase Solutions
Authors: Trujillo J. , Brito A.
Published: May 2009

The Jusepin main station is a facility designed to process 460.000 B/D of oil and 500 MMSCFD of natural gas produced from El Furrial field, located in the northeastern Venezuela. It consists of eight modules and started operations in late 80's handling a relatively low GOR. A gas injection program was implemented in late 90's as secondary recovery method. As a result the GOR increased 3 times generating bottlenecks in the modules I, II and III. The modules II and III share the inlet and outlet manifolds and therefore, operate as one. An upgrade of the mid pressure separation trains and gas scrubbers of modules I, II and III was required as these surface handling facilities have proven to be the primary constrain limiting the operator's production increasing plan.

This paper will describe the facilities constrains and discuss the proposed debottlenecking steps based on integrating several multiphase simple solutions to address most problems. These problems include: constrained gas handling capacity, uneven phase splitting in the modules II and III common inlet manifold and presence of hydrodynamic slugs in the inlet lines. The Cylindrical Cyclone Gas Liquid (CCGL) separation technology was chosen to increase the modules separation capacity due to its compactness, fabrication simplicity and proven high efficiency. Two identical CCGL arrangements were proposed, one for module I and the other for modules II and III. Two solutions were selected to promote the even flow distribution: a new symmetrical common inlet manifold for the modules II and III and flow splitters in every T-junction of the new inlet manifolds. Finally, the dimensions of the inlet lines were designed based on the classical Kelvin Helmholtz theory to promote the transition from slug flow to stratified flow.

The combination of these simple multiphase solutions will enable to double the current separation capacity of the modules and reduce the liquid carry over to the compressor plants maintaining the operational interruptions and downtime caused by modifications and tie-ins at a minimum.
Enabling Technology: An Overview of Offshore Innovations in the Oil Industry
Authors: Amado L. C. N.
Published: May 2009

Big accumulations found in the past are not likely to occur again. On the contrary several small size reservoirs may still be there, unless a new play be discovered. With global demand for oil decreasing, small accumulations may deliver the goods but and easy oil has become scarcer and we need to start looking at more difficult reservoirs from which to produce hydrocarbons. The actual production decline in existing fields may pose a challenge in the future together with geopolitics and technology. depletion rates and Geopolitics are complex variables to predict. Technology on the other hand can still be designed fit for purposes. This paper is about the road map to technology, including innovations and emerging ones, that will be needed by the oil industry to succeed in unlocking new plays. It is about enabling technology, i.e, to make technology able to do something for us now.
The Transient Well Test Analysis of Fractured-Vuggy Triple-Porosity Reservoir With the Quadratic Pressure Gradient Term
Authors: Nie Renshi , Jia Yonglu , Yu Jia , Liu Bin , Liu Yongliang
Published: May 2009

This paper aims at triple porosity reservoir with fracture and vugs, according to basic percolation principle the nonlinear well testing model with quadratic pressure gradient is established, considering wellbore storage and skin, for both the unsteady interporosity flow of the matrix to fracture and the unsteady interporosity flow of vugs to fracture. By use of variable substitution, linearizing the flow equation, the model is solved, and the Laplace space analytic solution is obtained, and then the real space solution is procured by use of Stehfest numerical inversion. So the pressure and the pressure derivative log-log new type curves are drawn up. Sensitivities of the type curves affected by different parameters are analyzed, including the influence of the quadratic pressure gradient coefficient β, fluid capacitance coefficient and interporosity flow factor, which are the main parameters that can reflect the traits of fractured-vuggy triple porosity reservoir. The impact of (lower case beta) under certain conditions is extremely intense, and the dimensionless pressure error may be up to 20% and dimensionless pressure derivative error may be up to 30%. Especially for low permeability reservoirs and heavy oil reservoirs, there is a bigger β; therefore the deviation of type curves between the linear model and nonlinear model is much obvious.

In the end, the example match explanation of a Carbonate well in Tarim oilfield is made, which shows that there are some differences in the explanation results between linear and nonlinear model, and the error of explanation results is very close to theoretical error, so the quadratic pressure gradient should not be neglected, and that the nonlinear percolation law is the actual flow law of oil in porous medium, and that the parameter values of nonlinear model explanation are more precise than those of linear model explanation, so the research on the nonlinear flow model and its application with quadratic pressure gradient should be undoubtedly strengthened and stressed. The results available in this paper can be further used in the study of the flow rule and the well test analysis of fractured-vuggy carbonate reservoir.
Assessment of the Potential and Economic Performance for ECBM Recovery and CO2 Sequestration
Authors: Gonzalez R. , Schepers K. , Riestenberg D. , Koperna G. , Oudinot A.
Published: May 2009

An Enhanced Coalbed Methane (ECBM) reservoir simulation study was performed to investigate what levels of initial permeability would be required to successfully implement a CO2 injection project for different levels of coal rank, and whether advanced development strategies could extend the window of applicability to lower permeability coal reservoir environments. To perform the study, a matrix of simulation scenarios that consisted of three coal ranks (low, medium and high), three permeability values (1, 10 and 100 mD), three types of injection wells (vertical damaged, vertical stimulated, and multi-branch horizontal), and two types of production wells (vertical and pinnate) were established.

Results, initially analyzed from a production perspective, lead to unexpected conclusions stimulating the controversy and the initiative for future research. For instance, due to the high CO2/CH4 replacement ratio for low rank coals, and the associated coal swelling and permeability reduction, the study indicated that primary recovery production is essentially identical to those reservoir productions under the proposed injection schemes (and any considered permeability level). Certainly, pinnate producers showed better performances than vertical ones. For medium rank coals, successful sweep can be achieved with vertical wells in a high coal permeability environment, but advanced pattern strategies would be required if the permeability is in the other orders. In high rank coals, coal swelling with CO2 injection is minimized, so successful sweep can be achieved in the high and medium coal permeability environments with vertical wells, but advanced pattern strategies would be required in a 1 mD coal permeability environment.

Corresponding economic analyses accompanying the production implied additional perspectives to be considered for decision management. Promising scenarios from the production point of view are not necessarily profitable under relatively standard conditions. Due to the serious limitations in the existing need knowledge base, these findings can be used as initial screening criteria for identifying reservoir environments and development strategies amenable to CO2-ECBM/sequestration projects.
Optimization and Process Control of a Reverse Osmosis Treatment for Oilfield Brines
Authors: Barrufet M. A. , Mareth B. C.
Published: May 2009

Fresh-water resources in many of the world's oil producing region are scarce, while produced water from oil wells is plentiful, though high salinity and other contaminants make it unfit for most applications. Disposing of this water is a great expense to oil producers. This paper advances a technology developed to treat produced water by reverse osmosis and oil adsorption to render it suitable for agricultural or industrial use, while simultaneously reducing disposal costs. Pilot testing of the process thus far has demonstrated the technology's capability to produce good-quality water, but process optimization and control yet to be fully addressed are focuses of this work.

We developed a computer model of the process using a dynamic simulator, Aspen Dynamics, to determine the energy consumption of various process design alternatives, and to test control strategies. We proposed process control schemes using basic feedback control methods with PI controllers. By preserving the mechanical energy of the concentrate stream of the reverse osmosis membrane, we found that process energy requirements can be reduced several-fold from that of the previously developed configuration.
Evaluation of Renewable Energy as Source of Power for Desalination of Oilfield Brines
Authors: Barrufet M. A. , Mareth B. C.
Published: May 2009

A hybrid system of wind, solar, and diesel generators could provide an efficient alternative for powering water desalination projects in remote oilfield locations in Texas. Disposal of produced water from oil and gas wells is a costly procedure for production companies, but water-to-oil production ratios exceed 10:1 (by volume) at many wellsites. Much of the petroleum produced in the United States and elsewhere is found in arid regions that could benefit greatly if the produced water could be purified sufficiently for agricultural, industrial, or potable use. Our previous research identified and validated treatment options capable of recovering a high proportion of fresh water from oilfield brine. In this paper we further the earlier research by examining the possibility of using renewable energy to power the units in "off the power grid" situations. A macro-driven spreadsheet was created to allow for quick and easy cost comparisons of renewable energy sources for a variety of scenarios. Using this tool, wind and solar costs were compared for cities in regions throughout Texas. The renewable energy resource showing the greatest potential was wind power, with the analysis showing that in windy regions such as the Texas Panhandle, wind-generated power costs are lower than those generated with diesel fuel.
Acid Stimulation of Geothermal Wells in Central America
Authors: Gomez Julio , Forero Leandro , Barrios Luz , Porras Enrique
Published: May 2009

Unconventional energy sources have become one of the keys to keep the world energy supply along with a sustainable development. In Central America, geothermal power is one of the most important energy sources, given the limited fossil fuel reserves in the area. The region imports 75% of its energy requirements, and geothermal-generated electricity in many countries represents 10 – 25% of the national supply. In fact, Central America is one of the world's richest regions in geothermal resources, according the world energy council.

Despite that the region has an estimated potential for geothermal electricity generation of 4,000 MW, the actual installed capacity is only 508 MW (CIA world fact book). Most of the geothermal projects in Central America produce below their potential due to two main factors: depletion and low productivity (or injectivity) due to scaling in tubulars and formation damage. The damage is typically due to several causes, including drilling mud damage, production fines migration, silica plugging and scales in the reservoir.

This paper describes the results of a five-year well stimulation campaign in El Salvador and Nicaragua, in several geothermal fields, run by different operators. More than 20 stimulation treatments were performed using different acid systems in volcanic and metamorphic rocks. The laboratory observations, their analyses and corroboration with the field data show that the combination of a properly designed treatment and special acid blends has lead to significant improvements in the stimulation of such reservoirs. Comparison of results in different reservoirs with varying stimulation treatments is also included as reference.
Valuation of a Real Options Portfolio
Authors: Oscar Bravo Mendoza , Alfredo Mogollón Monroy Luis , Dario Parra Vega José
Published: May 2009

This study aims to define a methodology supported in the concept of Real Options that will allow measuring the impact of variations in the execution of projects, on the value of the investment portfolio of the Production Vice-presidency of Ecopetrol S.A. (PRV). The proposed methodology involves the classification of the potential value of the Real Options and the valuation of the same using the Binomial method, the Montecarlo simulation, and the calculation of explicit volatility; while proposing the 3D graphic representation of the so called portfolio of Real Options.

The resulting methodology was validated using a real case of variation in two projects of the PRV portfolio in the year 2006 and it was possible to determine the way such change impacted the value of the same. This study aims to generate an important advance in management's way of thinking at Ecopetrol S.A., and the petroleum industry at large, basically in the recognition of the value that the sagacity of management decisions, regarding investment projects, has over the portfolio of the company.
Three Levels of Zonal-Isolation Assurance Deployed To Maximize Life of Well Cement-Sheath Reliability and Value: Case Histories From Latin America
Authors: Ramos X. , Martinez C. , Hunter W. , Ravi K.
Published: May 2009

The main purpose of the primary cement job is to provide zonal isolation for the life of the well. To achieve good initial annular isolation and allow the formation to be produced reliably, it is necessary to effectively displace all the drilling fluid from the well.

This can be achieved by using a combination of recognized industry best practices, such as centralization, drilling-fluid conditioning, application of spacers and flushes, maximizing displacement rates, and movement of the casing. Conventionally, success can be measured using a variety of cement-bond logs. Such logs are generally run after cement- slurry placement and before well operation; therefore, they only provide an initial assessment of the annular isolation achieved.

Work has shown that an initially competent cement sheath assessed using a cement-bond log can be damaged under the stresses exerted on it during the life of the well. These stresses can range from planned changes in wellbore-fluid density during the completion phase of a well to unpredictable well events. Therefore, to fulfill the main purpose of a primary cement job, a life-of-well approach to cement-sheath design is recommended.

This paper describes the successful use of three levels of zonal-isolation technology used to improve reliability and productivity for a number of wells in Ecuador. The first level of zonal-isolation technology used was finite-element-analysis (FEA)-based modeling to determine if the cement sheath would withstand the predicted operational loadings on the well. For the second level of zonal-isolation technology, an engineered-cement system with suitable sealing properties for the well was designed, developed, and deployed. For the third level, swell-packer technology was used to address the potential challenge of incomplete mud displacement.

A comparative analysis of conventional cement versus deployment of the three levels of life-of-well zonal-isolation technology is provided.
Lessons Learned From Relative Permeability Modifications in Colombia, South America
Authors: Gonzalez Pinto S. , Gutierrez M.
Published: May 2009

Description

This paper discusses well-interventions in Colombia that use a new generation of polymeric selective-water-reduction (SWR) product for selected candidates, treatment definition, differences of composition, radius of penetration, stages according to formation petro-physical properties, and well-productivity response in the short and long term. The evolution and improvements in technology over the past five years and its application in Colombia will also be discussed.

Previous papers have presented databases with information from interventions around the world, including case histories from Colombia (Dalrymple et al. 2007). This paper will focus on more detailed information for selection, treatment, and operational procedures in Colombian fields.

Application

There are hydrocarbon-producing formations in Colombia that have productivity limitations because of their high relative-permeability to water. This condition has generated increased tendencies to water-coning, historical and gradual water cut increases, and promoted a negative impact during the productive well life. This technological application includes new perforated wells (which are characterized for a potential rapid water-coning based on the geographical area or the formation) or producing wells in mature fields where the intervention still presents economical benefits. Information will be presented from wells with zones covering mid-to-high permeability, clean sandstones, and argillaceous sandstones at temperatures ranging from 125 to 250°F.

Results, Observations, and Conclusions

There are records of successful treatments, allowing for a reduction in the water to oil ratio, with increased productivity which has been maintained for more than three years. It has been possible to identify benefits from the technology, its evolution, and improvements during recent years. However, candidate-selection criteria have been continuously adjusted, which has generated more successful cases.

Significance of Subject Matter

Selective water reduction (SWR) is a viable technology with an extensive history of applications worldwide, and its usage has increased during the last five years in the productive basins of Colombia. A strong, continuous improvement effort has been in place for better reservoir characterization, understanding of water-production mechanisms, laboratory protocols, candidate selection, treatment design (volume estimation, placement techniques), and treatment follow-up.
Long-Term Post-Frac Performance Analysis Based on Flowback Analysis Using Chemical Frac-Tracers
Authors: Munoz A. V. , Asadi M. , Woodroof R. A. , Morales R.
Published: May 2009

Chemical frac tracing is used to evaluate flowback and cleanup efficiencies for eight different wells in a field located Central America. The technique utilizes a family of unique, environmentally-friendly, fracturing fluid compatible chemical tracers to quantify segment-by-segment recovery for individual fracturing treatments and stage-by-stage recovery for multi-stage fracturing treatments. Each well was traced with a number of different tracers during hydraulic fracturing. Upon flowback, samples were collected and analyzed for tracer concentrations. With the use of the mass balance method, total flowback and flowback efficiency for each stage were calculated. Production for each well was closely monitored for three years. This paper presents in-depth details relating short-term total flowback and fluid stage-by-stage flowback efficiencies to the long-term post-frac performance.