bluuebunny/crossref_metadata_2025 huggingface dataset:
Effectiveness of Hormonal and Surgical Therapies for Cryptorchidism: A Systematic Review
Authors: Penson David , Krishnaswami Shanthi , Jules Astride , McPheeters Melissa L.
Published: May 2013

BACKGROUND AND OBJECTIVE:

Controversy remains concerning the optimal treatment approach for cryptorchidism. The objective of this study was to assess effectiveness of hormone therapy or surgery for cryptorchidism.

METHODS:

We searched Medline and other databases from 1980 to February 2012. Two reviewers independently assessed studies against predetermined criteria. Two reviewers independently extracted data and assigned overall quality and strength of evidence ratings using predetermined criteria.

RESULTS:

Fourteen studies addressed effectiveness of hormonal treatments, and 26 studies addressed surgical intervention outcomes. Hormonal treatment is associated with testicular descent in some children, but rates generally do not exceed those seen with placebo by >10%. Surgical treatment is associated with success rates of testicular descent ranging from 33% to 100%, depending on surgery. Weighted success averages were 78.7% for 1-stage Fowler-Stephens (FS), 86% for 2-stage FS, and 96.4% for primary orchiopexy. Descent rates were similar among studies comparing laparoscopic and open surgeries. Reported harms of hormonal treatments were mild and transient. Adverse effects specifically associated with surgical repair were rare.

CONCLUSIONS:

The body of the reviewed literature comprises primarily fair- and poor-quality studies, limiting our ability to draw definitive conclusions. Hormonal treatment is marginally effective relative to placebo but is successful in some children and with minimal harms, suggesting that it may be an appropriate trial of care for some patients. Surgical options are effective, with high rates of testicular descent (moderate strength of evidence for FS procedures, high for primary orchiopexy). Comparable outcomes occur with laparoscopic and open approaches.
Magnetic Resonance Imaging for Locating Nonpalpable Undescended Testicles: A Meta-analysis
Authors: Krishnaswami Shanthi , Fonnesbeck Christopher , Penson David , McPheeters Melissa L.
Published: May 2013

BACKGROUND AND OBJECTIVE:

Preoperative imaging techniques may guide management of nonpalpable, cryptorchid testicles. We evaluated conventional MRI for identifying and locating nonpalpable testicles in prepubescent boys via meta-analysis.

METHODS:

Databases including Medline were searched from 1980 to February 2012. Eligible studies included ≥10 boys with cryptorchidism/suspected cryptorchidism and reported data on testicular presence/absence and position (abdominal, inguinal, or scrotal) as determined by imaging and surgery. Two investigators independently reviewed studies against inclusion criteria. We captured the number of testicles that were correctly and incorrectly identified and located, relative to surgically verified status, and estimated sensitivity and specificity by using a random-effects model.

RESULTS:

Eight unique prospective case series included 171 boys with 193 nonpalpable testicles (22 with bilateral testicles). Surgery identified 158 testicles (81.9%) present and 35 absent. MRI correctly identified testicles with an estimated median sensitivity of 0.62 (95% Bayesian credible interval [BCI]: 0.47–0.77) and a specificity of 1.0 (95% BCI: 0.99–1.0). MRI located intraabdominal testicles with a sensitivity of 0.55 (95% BCI: 0.09–1.0) and inguino-scrotal testicles with a sensitivity of 0.86 (95% BCI: 0.67–1.0). We were not able to obtain estimates for MRI sensitivity or specificity for locating atrophied testicles. The estimated specificity for location-specific testicles reached almost 100%.

CONCLUSIONS:

Conventional MRI has low sensitivity for estimating the population sensitivity for identifying the presence of nonpalpable cryptorchid testicles. When testicles are identified, MRI is poor at locating both atrophied and intraabdominal testicles but performs modestly well in locating those in the inguino-scrotal regions.
Relaxation and relief in stressed solids in terms of superellipse equation: concrete
Authors: Blechman Isaak
Published: May 2013

There is a large group of monotonic exo-processes, such as relaxation, shrinkage and maturity, which is realised over finite time and whose first derivative is infinite at the beginning of the process and zero at the end. The differential equation of exo-processes is given in this paper. Its analytical solution represents the left-hand upper quadrant of a superellipse and contains the time-operator, which links the exo-process with time. It is shown that relaxation can be successfully described by an exo-equation without recourse to viscosity, plasticity, rheological models or regression equations. The analytical expression for the operator of relaxation comprises three material parameters – the duration of total relaxation, the actual potential of relaxation and the exponent of the superellipse. The half-realisation factor, which reflects the rate of relaxation, is defined. The operator of relaxation is independent of the stressing, being a transparent function of time. It correctly represents the stress drop even for a fraction of a second, a fact of the highest importance in the context of fatigue. The superellipse equation describes relaxation in a wide range of solids besides concrete, giving clear evidence that it is a distinct process with its own physics and rules. The operator of instant relaxation, called relief (usually taken as a decrease in the apparent elastic modulus) is obtained from the equation of relaxation, where the time under load is represented by the reciprocal of the rate of loading. The operator of relief is independent of the stresses and is constant for a fixed loading rate. For structural concrete under a normative rate of loading, relief can account for 18% of the decline in the static versus dynamic modulus of elasticity.
Behaviour and design of members with monosymmetric cross-section
Authors: Taras Andreas , Gonzalez Puig Manuel , Unterweger Harald
Published: May 2013

Columns, beams and beam–columns with monosymmetric cross-sections are very frequently employed in steel structures. In this paper, the realistic, elasto-plastic buckling strength of such members is studied by means of non-linear numerical analyses and compared with the design rules found in Eurocode 3, the British Standard BS5950 and a new design proposal implemented in the Austrian national annex to Eurocode 3. The conservatism of the code regulations is highlighted, along with the codes' inability to capture the characteristic buckling behaviour of monosymmetric sections. For the basic load cases of pure axial compression, N, and pure bending moment, My, the source of the inaccuracy is shown to lie in the use of the buckling curves for flexural buckling as the basis of design. For beam–columns (load case N + My), it is shown that the sign of the bending moment (which can cause compression in either the smaller or the larger flange), in combination with an axial compression force, can cause remarkable differences when compared to the behaviour of double-symmetric sections.
Implementation of Bottom-Drive Progressive-Cavity Pumps Technology in La Cira-Infantas Oil Field as a Reliable Artificial Lift Method
Authors: Bohorquez M.. , Rubiano E.. , Labrador L.. , Suarez M. C.
Published: May 2013

Most common failures in the conventional artificial lift systems (Progressive cavity pumps and Sucker rod systems) currently used in La Cira - Infantas field are due to rod string and tubing failures; mainly root causes identified are friction rod string-tubing and combined friction-corrosion which causes both rod and tubing failures. The aim of the bottom drive progressive cavity pumping systems also called Electrical Submersible Progressive Cavity Pumps (ESPCP) project in La Cira Infantas Field is to improve artificial lift systems run life by reduction of premature failures occurred in the rod and/or tubing string.

ESPCP technology is a combination of Progressive Cavity Pump (PCP) and Electrical Submersible Pump (ESP) as an innovating artificial lifting method integrates the advantages of both systems, with compact surface equipment at the same time. PCP pump is an excellent choice for heavy oil and sandy fluids; however, rod pumps and rod driven PCP’s has also a limitation in highly deviated wells, pump speed and pump depth. By eliminating the need to drive the pump from surface by using a rod string represents a significant increase of equipment run life, reducing operating costs by intervention.

Field test was performed as initial phase by installation of three systems, successfully running at this point. Phase two was the implementation of 17 systems in different flow ranges. This paper will discuss the technical and economical advantages, highlights, specifications and history cases. Finally, phase three is the implementation of ESPCP in the field as preferred system to produce the called intermediate flow rate wells.
Automated Surface Gas Handling Through Expert Systems for Optimization of Artificial Lift Systems
Authors: Ramírez Miguel , Brunings Carlos
Published: May 2013

In reservoirs with a gas drive production mechanism, as the down hole pressure drops below the bubble point, gas breaks out of solution, and depending on the gas to oil ratio (GOR), the performance of oil wells with different artificial lift pumping systems installed are directly affected by the presence of free gas in the fluid. As a result, pump volumetric efficiency decreases reducing production, affecting the life cycle of the pump, and increasing costs due to the need of rig intervention for installing gas separators, or different assemblies for gas handling devices such as charge, tapered or two stage pumps in order to improve this volumetric efficiency.

Two newer systems for handling gas at the surface have been applied in high GOR wells in the heavy and extra heavy oil wells of Eastern Venezuela. The first system consists of implementing a closed loop device for controlling the pressure of the annular of a well to an optimal pressure value. The control algorithm based on techniques from expert systems has been applied successfully in several wells. Basically, when the pressure of casing is being controlled by an automated pressure control valve set at an optimum value, it causes a variation of the dynamic fluids reducing the amount of free gas in the annular space and pump.

The second system consists of a PCP (progressive cavity pump) device that measures fluid load through a load cell installed at the drive head of the surface equipment and detect variation in dynamic fluid, torque and motor load and surface pressure of the flow line are also recorded, and adjust the velocity of the pump with the variable frequency drive controlled by an expert system, which runs in a programmable logic controller developed for optimizing PCP. All these two systems have improved production and run life in more than 20% in different wells in which have been evaluated.
Buckling Prevention Using the Tensioning Device
Authors: Langbauer Clemens , Chevelcha Elena , Hofstäetter Herbert
Published: May 2013

A large fraction of artificially produced oil from mature, almost depleted reservoirs is lifted with sucker rod pumps. To increase the oil recovery factor under profitable conditions the objective is to reduce the operational costs, consequently decreasing the required number of maintenances and interventions. An essential cause of failures within rod pumps is buckling of the sucker rod string which occurs if the compressive load in individual rods exceeds a critical value. It causes a reduction of the volumetric efficiency and an increase of erosion and corrosion. The meantime between failures (MTBF) is relatively low and expensive changes of the rod string are required.

This paper presents an approach to prevent buckling by tensioning the rod string during the whole pumping cycle with the tensioning device, which is integrated in the rod string below the pump plunger. In addition, an optimization of the tapered rod string is performed to reduce the mass of the reciprocating rod string. The system analysis is performed by a simulation of the downhole installation, which is verified by numerous dynamometer measurements, from the surface and downhole, of different operating oil wells. The result of the simulation is the distribution of the tension in the sucker rod string from the polished rod to the pump plunger. With this knowledge, a rod string with optimum usage of material strength and crosssections is designed.

The tensioning device was already tested in a sucker rod pumped oil well in Austria. The result was a saving of electrical energy costs for the driving unit, and reduced number of workover operations. The tensioning device is simple but efficient and can be used within each sucker rod pump application. It prevents the system from buckling with a minimum amount of investment.
Gas Lift Smart Flow Integrates Quality and Control Data for Diagnostic and Optimization in Real Time
Authors: Al-Jasmi A.. , Goel H. K. , Querales M.. , Lopez C.. , Carvajal G. A. , Moricca G.. , Vellani R.. , Villamizar M.. , Rodriguez J. A. , Velasquez G.. , Yong Z..
Published: May 2013

Intelligent digital oilfield (iDOF) operations include the transfer, monitoring, visualization, analysis, and interpretation of realtime data. Enabling this process requires a significant investment in surface, subsurface, and well instrumentation and a sophisticated infrastructure for data transmission and visualization. This upgraded system can then transfer massive quantities of data. Automated intelligent workflows, referred to here as "smart flows", convert this raw data into real information at the right time.

To increase efficiency and decrease downtime in operations, oil companies have invested heavily in digital oilfield infrastructure. An important part of the puzzle is transferring data from the wellsite to the office in real time and using that data to optimize production systems. The challenge is to extract real-time information from raw data at the right time to affect the management of the fields, which is the primary goal.

North Kuwait’s Sabriyah field is operated using an intelligent digital oilfield operation by a major Middle Eastern oil company. Part of the intelligent digital oilfield project is a smart flow dedicated to monitoring, diagnostics, and optimization of gas lift (GL) wells. Leading-edge technologies—such as subsurface equipment and sensors, advanced diagnostics based on artificial intelligent agents, analysis of sensors signals, and automatically identifying GL optimum operating-conditions—are used to accomplish this goal.

Using a steady-state nodal-analysis model combined with an artificial intelligent technique, the smart flow is designed to provide rapid diagnostics and optimization in real time, generating actions, such as decreasing and increasing the gas lift injection rate and choke setting. The ultimate benefit is timely detection of those signals that foretell unexpected well downtime or equipment failure. The paper describes the main functionalities of the GL smart flow as a powerful optimization tool capable of providing an interactive monitoring system to assist the company in managing its GL-operated wells.
Optimizing an Artificially Lifted Reservoir using ESPs and Real Time Information
Authors: Paez Gerardo
Published: May 2013

Real time data is not a new concept to ESP lifted wells. Many systems are available to gather and transmit data, coupled with services and software to help analyses data. However, the potential value of real time surveillance systems is often not fully realized. This paper discusses case studies of how information from intelligent real time processes was used to optimize production, increase run life and manage ultimate production from the reservoir.

Each well was equipped with a panel running a real time nodal analysis well model which enabled the draw down on the reservoir to be controlled using the ESP. Target draw down or flow rate values where supplied to each processor which calculated the optimum mode of operation for the ESP. Techniques included virtual real time well testing, balancing of draw down on the reservoir in real time using the lift system as a control, and the importance of protecting the lifting equipment during the automation process.

Oil production gains ranging from 6 to 50% were achieved using the system, some of which occurring on wells thought to be previously optimized. ESP uptime was improved through real time monitoring of well status, and pump operation in difficult wells improved through use of the advanced ESP diagnostics information.

The novel architecture of the system showed that parallel processing power enabled each well to automatically adapt to changes in reservoir or flow line performances in real time as the target draw down values where achieved. Fine tuning of the lift system frequency (pump speed) and wellhead pressures allowed each well to be optimized in line with the reservoir engineers recommended bottom hole flowing pressure requests. The individual production and draw down targets could be adjusted up or down at the reservoir engineers request and the system automatically recalculate the optimum operating condition for the lift system.

The real time system showed how draw down targets could be adjusted to enhance overall production in addition to achieving the targets through real time automation of each ESPs operation
Wireless Simultaneous Acquisition and Analysis of Dynamometer and Fluid Level Data for Real-Time Monitoring of Well Performance
Authors: McCoy J.N.. N. , Becker Dieter , Fernandez Gustavo , Podio A. L.
Published: May 2013

Real time analysis and visualization of the performance of a rod pumped well are achieved using multiple small and compact wireless sensors that simultaneously transmit acquired data to a digital laptop manager that integrates the measurements, displays performance graphs and provides advanced tools for analysis and troubleshooting of the pumping system.

Battery powered wireless sensors for fluid level, pressure and dynamometer data acquisition are easily deployed and quickly installed on the well. The laptop manager automatically recognizes and commissions the sensors. The user sets up and controls the acquisition of data which may include multiple sensors that synchronously monitor variables such as tubing and casing pressures, fluid level and polished rod acceleration/position and load as a function of time. Elimination of cables and connectors improves the reliability of the hardware and data while speeding up the set-up-tear-down process. The user interface presents a smart instrument rather than a complex application.

Among the many innovations provided by these well performance analysis tools stand out the real time visualization of the operation and fluid distribution in the down-hole pump, the simultaneous display of quantitative surface and pump dynamometer graphs in conjunction with fluid level and wellbore pressures. Acquired data, wellbore description and pumping system characteristics are saved as a historical data base creating a continuum of the well’s information and performance for direct comparison and detailed analysis.

The paper describes the hardware and user interface, the procedures for installation and acquisition and several examples of field data and well performance analyses for a variety of rod pumping installations.
Implementation of New Seal Design to Improve ESP Performance in Corcel Field
Authors: Sarkis N.. , Guerra W.. , Moreno L. F. , Salazar I.. , Cuellar H.. , Pirela J.. , Urdaneta B..
Published: May 2013

The main artificial lift method used in the field Corcel, located in the Llanos Basin, since its beginning in 2007, is the electric submersible pump (ESP). Until April 2011, 9 ESP units were running with an average run life of 218 days and, during those four (4) years, a total of 37 installations were performed, of which 21 were associated to ESP failures. As a result of the high number of failures and low run life presented, an interdisciplinary research group was created, including production, completion, reliability, product and applications engineers from Petrominerales and Baker Hughes, with the ultimate goal of increasing the life of the equipment, reducing intervention costs and minimizing deferred production.

Failure analysis focused on two main points: identification of the affected components and root cause of the failures. First results evidenced that the seal was the most affected component of the Electric Submersible Pump, and, more specifically, the elastomer bags and mechanical seals. Although the initial root cause of failure was not clear and was associated exclusively to a problem of compatibility between the seal elastomers and the well fluids, a further detailed analysis was performed to determine other possible failure mechanisms of this component.

This paper aims to describe and analyze the failure mechanisms, as well as to provide the solutions designed specifically to mitigate them, starting with the development of a new technology such as the SP1 seal to substantially improve the lifetime of the equipment. An illustration of one of the most important applications of fluid characterization for the sizing or selection of an ESP is presented, as well as the results in reduction of deferred production and intervention costs.
Development of a PCP Dynamic Safe Drive with Viscosity Super Brake and successful deployment in an Argentine Field
Authors: Young Esteban , Young Lucas , Sonsino Sergio , Bertomeu Fernando , Villota Daniel , Modon Alberto , Zubiri Juan , Pontelli Nicolas , Caunedo Carlos
Published: May 2013

Synopsis

The aim of this work is to present a PCP (Progressing Cavity Pumps) drive-head, which main feature is its dynamic viscous brake and its safe operation due to the lack of pulleys, belts and external mobile parts.

The drive-head was the result of 3 years of research and investigation in a joint effort between ITBA (University of applied sciences) and the service company. The final prototype after the development was installed at an operator’s well in April 2012, where it performed optimal. The results of the tests made during the prototype trial are shown in the present document.

The main conclusions after the trials are a shorter braking time with the viscous system, a safe operation and with a low maintenance level, an efficient rod string back spin control, and a quick oil production at surface at the well start up.
"Importance of Preventive and Predictive Maintenance Plan in Reducing Occurrences of Failures (MTBF-MTTR) - Rod Pumping Systems: Hydro-Pneumatic Surface Units, Experience in Mexico"
Authors: Galvan R.. , Rucabado J. J. , Rubio Arvilla C. A.
Published: May 2013

The operational capacity of the hydro pneumatic surface units for rod pumping applications is affected when a proper maintenance program is not follow, resulting consequently in premature failures of equipment components, units running out of operation with downtime and increased of corrective maintenance. This whole problem leads to low production of hydrocarbons and hence to a loss of revenue associated with deferred production.

The maintenance plan is also an effective method of allowing a lengthening of run life of the unit and its components, helps identify opportunities to focus resources and efforts, as the correct distribution of technical personal and planning work, thereby reducing the occurrence of faults.

To achieve beneficial results, it is essential to make a detailed analysis of the components that integrate the system and support it with technical recommendations of manufacturers, also, to take a judicious control and supervision of maintenance work and to have the right materials and techniques to be performed.

With the implementation of preventive and predictive maintenance plans, it has achieved operational reliability of the equipment, and although the learning curve is unsurpassed in its totality, has gained the confidence to deal with emergency situations and thus not incurring repetitive failures.

The lack of immediate availability of retrofit, due to poor planning and late repair times of the units, have raised concerns about investing towards the systematization of a maintenance plan, avoiding with this, units running out of operation, achieving customer satisfaction and the opportunity to expand into new markets.

Recent evidence support that through the implementation of an effective maintenance program to hydro pneumatic surface units with a work age of 4 consecutive years may be competent with the current market, condition that can be measured by KPIs such as MTBF and MTTR, based in operational reliability. In the same way, knowing in detail its operation, has allowed the involvement in the development of other applications. This is a real case based in operations in Mexico.
Field Experience with the Application and Operation of Permanent Magnet Motors in the ESP Industry: Success Stories and Lessons Learned
Authors: Seczon Luis , Sagalovskiy Andrey
Published: May 2013

Since 2006, more than 2550 Borets permanent magnet motor (PMM) systems have been installed by oil companies. This paper will provide an overview of the application environment covered by these installations and contrast the performance for the ESP PMM system versus the traditional 2-pole, 3-phase ESP induction motor systems that were replaced. Results include the lessons learned, best practices developed, and benefits realized by the operator. The PMM practice will be of value to new operators as this technology is introduced to other regions of the globe as well as the expansion of this technology into the ESPCP-PMM market.
Experimental Study of a Poor Boy Downhole Gas Separator Under Continuous Gas-Liquid Flow
Authors: Ibarra Javier , Pardo Raimundo , Vega Libar , Carios Enrique
Published: May 2013

An experimental study of a "poor boy" downhole gas separator is presented. The poor boy design is simple, robust and unobtrusive, making mandatory its evaluation for further comparison with more elaborated designs. Laboratory results indicate the existence of two separation efficiency regions: a) high, nearly constant, efficiency zone for low liquid flow rates and b) efficiency is an almost linear function of the liquid flow rate, modified by both gas mass flow rate and gas density. A simple formula for separation efficiency calculation is provided to be used for the production of low viscosity oils.
Listening Sucker Rod Pumps: Stroke’s Signature
Authors: Chevelcha Elena , Langbauer Clemens J. , Hofstaetter Herbert
Published: May 2013

The general idea of the research is based on the assumption that an oil well with an installed Sucker Rod Pump (SRP) emits a characteristic sound spectrum that can be assessed. Every change to the system (wear, beginning failures, etc) should be reflected in a corresponding change of the sound spectrum, creating thus a correlation. The scope of the research is to study noise, produced by a well and to find whether there is a relationship between emitted noise and a production state of the SRP. Correlation will be researched on the basis of dynamometer readings and actual production events.

Noise represents a function of dynamic behavior of fluids, gas, downhole, and surface equipment. Sound created by this system is recorded in on-line mood with the help of a special device installed on the wellhead. The noise data then are transmitted, uploaded to a server, and available for processing. The analysis of the noise is based on Fast Fourier Transform (FFT), Power Spectral Density (PSD) estimation, together with statistical tools.

This paper presents first tests that are done with the purpose to find a stroke’s signature. By signature it is meant characteristics that describe the stroke the best. They are best reporting features: PSD distribution, Noise Flatness, Root-Mean Squared, frequencies of maximum PSD, etc.

The result of performed characterization with the help of signature concept, determines a pattern of SRP acoustically. This allows further application of acoustic diagnosis of SRP that helps identify many failures (like leaking tubing, standing and travelling valves, excessive loads, worn out rods, gas-lock, buckling, etc.) before they cause major damage or production loss.
Life Cycle Cost Analysis for the Nitrogen Over Hydraulic Pumping Unit
Authors: Hernandez Jesse , Galindo Jose Miguel , Charry Rivera Carolina del , Salas Carlos Mauricio
Published: May 2013

The "Superintendencia de Operaciones Orito Putumayo" is responsible for the exploitation of the Ecopetrol S.A. oil fields located in Putumayo and Nariño regions in southwest Colombia. The SOP is divided into five areas (Orito, Sur, Occidente, Nororiente, and Suroriente) covering over fifty fields of which sixteen fields are currently active. Economic evaluation of several mature oilfields of the SOP indicate that many operate at very close to the economic limit and in some cases the net present value are marginal and/or negative. It is for this reason that the "Superintendencia de Operaciones Putumayo" applied a Life Cycle Economic Analysis methodology whose objective was to estimate cash flow included in all phases of an investment life cycle. This includes design, construction, operation, maintenance, dismantling or conversion of this cash flow projected into the future and compared to similar investments. The evaluation considers the Net Present Value of the investment, including the installation of Nitrogen over Hydraulic pumping units in wells with variable characteristics and with high lifting cost. Lower capital acquisition cost, lower transport cost, lower installation cost and lower operation cost were confirmed. These results are being considered to optimize existing wells as well as improving economics for the drilling program in the western part of the region. Conclusions include an analysis of the impact on lifting cost of all fields.
First ESPCP Ultra High Temperature Application with Cyclic Steam Stimulation in the Kern River Field
Authors: Guerra Enrique , Webb Charlie , Lindo Octavio , Prather Josh
Published: May 2013

Artificial lift systems have encountered traditional challenges in the production of high viscosity oil-well fluids such as heavy and extra heavy crudes. These challenges included problems with sand abrasion, formation of emulsions (fluid shearing), high wellbore deviation (horizontal wells), scale deposition, and temperature and fluid rate limitations.

The development of ESPCP technology meant the synergy of PCP and ESP into a hybrid that takes advantage of the best qualities from both worlds. On one end, ESPCPs offer greater resistance to solids abrasion (solids production), high viscosity liquid production capability (positive displacement pump) and the low fluid shear characteristics of PCPs. On the other end, ESPCP systems may be deployed in high deviation wellbores, while still able to provide the substantial liquid rates and torque derived from ESP down-hole motors. The exploitation of unconventional resources, such as heavy oil thermal projects, has triggered the development and improvement of ESPCP technology for high temperature applications. In particular, the use of ESPCPs in heavy oil steam flood reservoirs with cyclic steam stimulation, such as in the well known Kern River field, poses a significant challenge to this artificial lift system.

This paper describes the experience and results of the first ESPCP pilot project known to the authors, where all parts of the subject unit are exposed to short, but direct cycle steam stimulation treatments.
Optimizing the Efficiency of Artificial Lifting Systems in the Production of Heavy Crude, by the Use of Electrical Heating in Surface Facilities
Authors: Jaimes M. G. , Durán J.. , Sanabria F. E. , Dorado R..
Published: May 2013

Until recent years, heavy oil was rejected as an energy resource for the inconvenience and costs associated with its production, but today, with the gradual depletion of deposits of light oil, its reserves have attracted the interest of oil companies and governments around the world. Estimated reserves of heavy oil in the world equal to three times the combined reserves of conventional oil and gas exist and are the safest source of energy in the immediate future of humanity.

One of the major drawbacks in the production of heavy oil in mature fields, is the low efficiency of artificial lifting systems, which is presented by the high frictional pressure losses that are handled by the system (subsurface equipment and recollection facilities), which occurs as a result of the high viscosity and / or direct emulsions (water in oil) of the produced fluids (viscosities above 500 cp.).

As an alternative to improve the efficiency of artificial lifting systems in the production of heavy oil in Colombia, from reducing viscosity of the produced fluids, was visualized the selection, evaluation and application in surface facilities of the technology of electrical heating., to ensure adequate conditions of extraction and recollection that will maintain optimal levels of production and release of lower-producing areas with higher API gravity.

This study presents a detailed technical and economic evaluation of the application of electric heating in surface facilities to optimize the efficiency of artificial lift systems in the production of heavy oil in fields operated by Ecopetrol in Colombia, including: nodal analysis to determine incremental production, evaluation of technical and economic benefits (net present value). This paper presents the application results in the Tisquirama field.

Finally, the main findings, conclusions, recommendations and field results obtained in this study are presented and among which are: Increased of the efficiency of the artificial lifting system in 100%.Increased of oil production in 100%.Unlock and producing of lower zones of high API gravity.
Insertion Problems in Tandem Progressing Cavity (PC) Pumps, Solving this on a Decision Tree
Authors: Carreno L. Jimenez , Rojas R. Rincon , Trujillo J. A.
Published: May 2013

Description of situation found during inserting process of rotors set inside of stators assembly in tandem or dual Progressing Cavity (PC) pump configurations. On the basis of the identified problems (i.e., people risks, downtime, extra costs, and production loss), we compiled them and generated a flow chart that can be used as a useful guide in making a decision.

The different alternatives and recommendations presented to solve the difficulties throughout the insertion process have general application; these operational experiences are specifically referred to La Hocha field in Colombia though.

We were able to optimize the execution of well planning using dual (PC) pumps because the operational time required was reduced from 6-18 hours to 1-2 hours in average. The oil production goals had fewer restrictions caused by less wells under (PC) pump completion services or corrective interventions. The personnel safety and equipments care were essential factors to improve the traditional procedures used in field; this aspect for both Oil Company (i.e., outsourcing and direct workers, and own installed equipments) and Services Company too (i.e., field technicians and engineers, rig, tools, and spare parts).

The synergy between both companies contributed to get operational excellence for this process, mainly effective communication between Company Man and (PC) pump leader in well location, and availability of all technical data. Besides time and money savings, a high QHSE impact was achieved thanks to implementation of better and safe practices and minimum operational non-conformances in oil wells where sand production is the problem and dual (PC) pumps are used as an effective solution.
Overcoming Nearly Three Decades of PCP Experience in Shallow Heavy Oil Field
Authors: Toelsie S.. , Mohan A.. , Kisoensingh S.. , Goerdajal P..
Published: May 2013

To date some 1,500 Progressive Cavity Pumps (PCP) are utilized for artificial lifting of averagely 15.6 API0 crude oil with average viscosity of 500 cp at reservoir conditions, from the Staatsolie wells to the treatment facilities. The single lobe pumps are installed at an average depth of 1000 ft, producing from unconsolidated Tertiary sand reservoirs with rates varying from 10 up to 2000 barrels BFPD.

The shift from pumping jacks to PCP's was made in the mid 80's due to the flexibility and improved efficiency in drivehead configuration as well as volumetric efficiency of the PCP system contributing to significant reduction in lifting cost per barrel fluid. The PCP has established its robustness being in operations for almost 30 years under varying well conditions such as increasing water-cuts and fluid production rates, decreasing reservoir pressures, fluctuating GOR's and in vertical as well as in approximately 500 deviated wells.

Pump stator material, by default nitrile based, has been fabricated to suit the low aromatics content in the crude. Typical stator failures encountered include cracks and blistering combined sometimes by pitting and abrasion. The Mean Time Between Failure (MTBF) ranges from 2 months to almost 25 years.

In 2008, the Nodal Analysis concept was introduced to compare IPR and VLP for optimization purposes. VLP curves were created by modeling the PCP as two tubes, for which the inner tube would represent the annular flow between the pump helical rotor and stator and outer tube for the rod-tubing flow. An advancement that allowed the user to select the appropriate pump based on required pump differential pressure. CFER well modeling for pump seating, hydraulic torque, rod-tubing contact, rod string as well as rod–tubing loads were analyzed and optimized for given wellbore trajectory and doglegs.

The paper presents the versatility of the PCP application in different downhole environments, the performance and challenges to mitigate the common failures. Results of field cases and software simulations will be presented for best practice recommendations for progressive cavity pump applications in shallow heavy oil reservoirs.
Implementation of an Integrated Artificial Lift Solution To Test Wells in Colombia
Authors: Leon-Quintero Diego Fernando , Robayo Roberto , Pachon Luis Edison
Published: May 2013

A developing technology involving the use of electric submersible pump systems (ESP), tubing conveyed perforating (TCP) and Drill stem testing (DST) tools in an all-in-one string design was implemented for the very first time in Colombia to accurately test the potential of non-naturally flowing wells.

With the implementation of this well test procedure, the perforation and production steps can be followed immediately during the same run, helping to decrease the operating time by reducing the running jobs required and, achieving a significant enhancement on the data gathering process by avoiding to kill the well after perforation and breaking the test into separate runs for testing string and the artificial lift method; situation which likely will damage the formation.

The use of a pod to fully encapsulate the ESP and hold the DST-TCP equipment is the key element that enabled the integration of the three technologies into a single run, allowing the study of the inflow performance relationship (IPR) by using the pump to create the optimum environment for perforating, increase the energy of the fluids to transfer them to surface and, obtain controllable production rates required when the formation pressure is not capable enough to do so in the typically called non-naturally flowing wells.

The successful integrated job performed during the first semester of 2012 has led to a growing interest in this technology and its use is expected to increase in the near future.
Backspin Analysis in Progressive Cavity Pumping Systems and its Impact on Safety
Authors: Magnoni P. J. , Pich P. J.
Published: May 2013

This paper describes the physical principles behind the backspin generated by stopping progressing cavity pumping systems (PCP). After describing each and every one of them, action items are recommended to help operators to mitigate risks and potential safety hazards, based on the field experience and applying modeling and simulations. The main goal is to create awareness over their characteristics and implicit risks and contribute with operators to manage PCP systems in a reliable and secure manner.

There is a wide range of surface equipment with different technologies to control backspin working in a variety of application conditions and this is why it is necessary to identify the criticality of each system and technology in terms of backspin and potential energy which must be released. It is also necessary to understand the right relationship between all variables involved and their hazard potential in case the backspin control system failed during the release of this energy.

It is highly recommended to take action and put barriers to minimize risks, such as the ones mentioned below: ■Preparation of hazard maps in terms of velocity of backspin■Proper backspin control technology selection for each application■Implementation of preventive maintenance programs■Non-destructive inspections to critical components.

In conclusion, throughout its content this paper expects to contribute to a safer operation, with the objective of protecting the physical integrity of individuals and operational reliability.
Influence of vineyard peach selections on vigour and initial yield in peach and nectarine
Authors: Zec Gordan , Fotiric-Aksic Milica , Colic Slavica , Vulic Todor , Nikolic Dragan , Oparnica Cedo , Jankovic Zoran
Published: May 2013

Seedlings (progenies) of eight selected vineyard peach genotypes obtained by
self and open pollination were examined in this study during three
consecutive years. Two progenies from unselected vineyard peach genotypes
with different geographic origin were used as a standard. Peach cv. Autumn
Glo and nectarine cv. Stark Red Gold were grafted on F1 generation of eight
vineyard peach selections and two standard progenies. Analysis of variance
indicated statistically significant differences in vigour and fruit
productivity between fruit trees grafted on different progenies of vineyard
peach selections. A high correlation was found between rootstock vigour and
fruit production of grafted cultivars. In addition, the principal component
analysis made it possible to establish similar groups of rootstocks,
depending on its influence to vigour, productivity and indexes of efficiency
of grafted peach and nectarine cultivar. The most promising rootstocks for
those two cultivars were PSK and 7S because grafted AG and SRG have high
fruit weight, initial yields and very satisfactory rootstock, scion and
canopy efficiency.
Osmotic stress tolerance, PGP traits and RAPD analysis of Bradyrhizobium japonicum strains
Authors: Marinkovic Jelena , Djordjevic Vuk , Balesevic-Tubic Svetlana , Bjelic Dragana , Vucelic-Radovic Biljana , Josic Dragana
Published: May 2013

The osmotic stress tolerance of B. japonicum strains assessed according to
their persistence in PEG solution. The lowest tolerance to osmotic stress was
observed in strain 511 (43.3%), and the highest tolerance was observed for
strain D216 (3.3% growth reduction in presence of PEG). PGP traits of B.
japonicum strains were tested. None of five B. japonicum strains produced
siderophore, strains 511 and 518 had the urease ability, and only B.
japonicum 518 strain showed the ability to solubilize insoluble tricalcium
phosphate. RAPD analysis, using AP10, BC318, AF14 and SPH1 primers, indicated
genetic differences between Bradyrhizobium strains. The first group (strains
3, 6 and 518) showed more than 80% similarity. Strains 511 and D216 formed
separate clusters. Difference between strains D216 and the other strains were
more than 60%, with maximum value of 72% in comparison with strain 511.
Plant-growth promoting (PGP) traits, osmotic stress tolerance and RAPD
analysis highlighted strain D216 as useful for further investigation of B.
japonicum impact on drought reduction in symbiosis with soybean.
Cytogenetic biomonitoring in a Serbian population occupationally exposed to a complex mixture of pesticides
Authors: Jovicic Dubravka , Pajic Jelena , Rakic Boban , Radivojevic Ljiljana , Pajic Milos , Janjic Vaskrsije , Milovanovic Aleksandar
Published: May 2013

The aim of this study was the analysis of chromosomal aberrations (CA) and
premature centromeric division (PCD) in people exposed to pesticides at work.
The research included 26 subjects occupationally exposed to pesticides, of
average age 39.89 + 8.66, and 32 control subjects of average age 40.57 +
6.57. Mann-Whitney U tests showed statistically significant differences
between the groups for mean values of all the examined variables. In
addition, Spearman?s (non-parametric) correlation test detected a positive
linear correlation between CA and PCD. The presence of mostly chromatid and
isochromatid breaks in the examinees indicates continuous exposure to
pesticides. The absence of complex chromosomal rearrangements points to
adequate protection of the subjects at their work places.
Dependence of the productivity of maize and soybean intercropping systems on hybrid type and plant arrangement pattern
Authors: Dolijanovic Zeljko , Oljaca Snezana , Kovacevic Dusan , Simic Milena , Momirovic Nebojsa , Jovanovic Zivota
Published: May 2013

Intercropping systems could improve utilization of the most important
resources (soil, water and nutrients), provide a better control of weeds,
pests and diseases, and finally higher productivity, especially under
rain-fed growing conditions. This study aimed to determine the effects of
three maize (Zea mays L.) prolific hybrids (FAO 500, 600 and 700) and the
spatial intercrop patterns on the above-ground biomass and grain yields of
maize and soybean (Glycine max L. Merrill), on chernozem soil type at Zemun
Polje, Belgrade, in 2003, 2004 and 2005. The experimental design was a
complete randomized block with four replications and three treatments: 3 rows
of maize and 3 rows of soybean in strips for each maize hybrid (three
variants, 3 rows of maize and 3 rows of soybean in alternate rows for each
hybrid (another three variants) and monocrops of both maize and soybeans. To
optimize the ecological and economic benefits of maize/soybean intercrop in
terms of yield, variety selection and compatibility of the component crops
should be made using established agronomic management practices involving the
two crops. Suitable maize varieties for maize/soybean intercrop systems are
varieties that have less dense canopy. These varieties would therefore have
lesser shading effect to the understory beans. However, establishment of an
appropriate spatial arrangement of the component crops would be essential to
alleviate negative effects especially on the less competitive crop. The
intercropping system in alternate rows showed significantly higher
above-ground biomass and grain yields in comparation with both the strip
intercropping system and maize monocrops in 2004. Soybean gave significantly
lower above-ground biomass and grain yield in intercrops than in monocrops.
Maize prolific hybrid growing in intercropping with soybean as legume crop,
increased productivity of cropping system, especially in favourable
agroecological conditions. Maize and soybean yields reduction could have also
been due to interspecific competition for resources such as nutrients and
water. Moreover, performance of the currently grown varieties in the
semi-arid regions depends on the amount of rainfall received during the
growing season.