bluuebunny/crossref_metadata_2025 huggingface dataset:
Lessons Learned From Well to Field Level in Developing Heavy-Oil Reservoirs Using Thermal Recovery: Case Studies
Authors: Mehranfar Reza
Published: September 2014

The objective of this paper is to show and demonstrate how technology and especially software application in the field of heavy oil can change our view regarding the method of development and economical feasibility of the pilots. Different real challenges regarding heavy oil exploitation and production have been addressed and the solution has been provided with best in class technology and software in the market at the time of these studies.

The first case is about injected steam conformance in a horizontal well and in a loose fluvial sand reservoir. The lack of conformance has been modeled and after that simulated using proper reservoir modeling and simulation applications. The second case which has been studied is evaluating and feasibility study of implementing of in situ combustion in thin sands which previous attempts of developing them with cyclic steam stimulation was not successful because of high energy loss to the over and under Burdon layers. The third case is to show how efficient production scenarios can be sensitized and selected with application of a reservoir simulator to surface coupler platform technology in a continuous steam injection project. The idea of applying this technology is to bring different domain knowledge and understanding in a common platform in order to optimize energy value.

In this study a wide variety of cases like different reservoir rocks and fluids will be reviewed and due to large amount of materials available the focus will be to a basic explanation of the situation, method of implementation of the technology or solution and ultimately final results that were concluded at the time of study. The idea is to show how different method of development can be considered for field development of heavy oil reservoirs and also how simulation and pilot studies can save a considerable amount of money in these projects.
Applied Technologies for Successful Cementing in Steam Injection Wells in Southern Mexico
Authors: Ramirez-Vazquez F.. , Hernandez-Enriquez R.. , Briseño H.. , Moreno-Colin S. E.
Published: September 2014

Steam injection wells are currently being exploited in the southern region of Mexico. These types of wells can present difficult challenges with respect to cementing operations. For example, the cement composition must be designed properly to withstand the extremely high downhole temperature induced by injected steam. Additionally, lost circulation should be minimized or prevented while cementing. It is also very important to help ensure effective mud removal and help prevent trapping fluids in the annulus, which might cause annular fluid expansion and casing collapse attributed to temperature changes during steam injection operations.

To overcome these challenges, combinations of optimized job procedures and technologies have been applied to wells under such significant conditions, demonstrating improved results. Temperatures the cement slurry encounters during and after placement are estimated using a simulator, which considers the heat transfer phenomena. Using a new generation of resin-based, nonmetallic centralizers attached to the casing has helped improve centralization. High performance thermal cements are the most suitable choices for cementing under these conditions. Displacement of mud has been enhanced using a state-of-the-art 3D simulator to help optimize rheological and density hierarchy.

Applications of these technologies have been successful, helping provide zonal isolation at production zones and helping minimize remedial work attributed to lost circulation. When evaluating cement bond logs (CBLs), the trouble zones present in the reservoir should be considered. These technologies can be applied using appropriate modifications for different global regions where similar challenges are encountered; additionally, they potentially provide cost-beneficial outcomes.
Issue Paper: Aquifer Integrity Under the Influence of Thermal Extraction of Bitumen and Heavy Oil
Authors: Rivera L. E.
Published: September 2014

The impact of underground effects triggered by thermal recovery of bitumen and heavy oils on aquifer integrity has yet to be addressed. Aquifer integrity can be defined as the physical and hydrodynamic setting for which safe groundwater storage and sustainable delivery of water quantity and quality is preserved. Like cap-rock, aquifer integrity under the influence of thermal extraction is expected to deteriorate due to Underground Thermal Effects (UTE), caused by geomechanical modification of the stress path at the reservoir level. Most popular thermal recovery methods causing UTE are Steam Assisted Gravity Drainage (SAGD), Cyclic Steam Stimulation (CSS) and Steam Flooding (SF). UTE associated with other forms of thermal recovery approaches such as in-situ combustion (ISC) have been less studied and might differ in nature and magnitude from the steam-based ones. Despite the fact, similar UTE are expected. This issue paper addresses the role of UTE on aquifer integrity under the influence of thermal extraction as identified for cap-rock integrity in the bitumen and heavy oil industry. Main UTE are heave, fracturing, lessen of well integrity and heat plume development, which develop or enhance underground process that ultimately impact aquitards and aquifer integrity. Such processes are gas migration, cross formational flow, interwellbore communication and element mobilization. Although impacts of UTE on caprock and reservoir integrity are well known to the bitumen and heavy oil industry, the same on aquifer and aquitard are less understood.
Assessment of Cold-Heavy-Oil Production With Sand CHOPS in Llanos Basin, Colombia
Authors: Andarcia L.. , Bermudez J.. , Suarez A..
Published: September 2014

Heavy Oil production has been subject of extended research and technological developments during the past 3 decades. These difficult resources have been economically produced by different methods thanks to new technologies and the adoption of best practices to achieve successful projects. However, other production methods have risen directly in the field by trial and error. This is the case of the cold heavy oil production with sands “CHOPS” which is an extended production practice mainly in Lloydminster, Canada. This method have make possible to produce thin sands at economical rates using big hole perforations in vertical wells without sand control. By letting the sand be produced in conjunction with the oil, the so called “wormholes” can be created within the reservoir. These wormholes are structures of about 1 inch diameter that can reach several meters of length beyond the producing well. These high conductive channels help supporting a sustained oil rate for several years using PCP pumps.

The formation of wormholes has already been technically proved during cold production tests carried out in a thin heavy oil bearing sand located in Llanos basin, Colombia. During this test, there was observed communication with another well 25 meters apart from the tested well. Light weight ceramic proppant used to gravel packed the nearby well has migrated to the producing well after sand production. The migration throughout the porous medium of man-made ceramic whit a diameter higher than 1000 microns evidences the creation of high-conductive channels or wormholes. Since then, the potential for CHOPS in this reservoir has been analyzed. The production potential under cold production with sand is studied by analogs and numerical simulation. Factors affecting the operational model needed to achieve a successful project are analyzed.
Evaluation of CO2-EOR Gas Injection in a Heavy-Oil Naturally Fractured Reservoir
Authors: Fuenleal Martinez Jose Nicolas , Abbaszadeh Maghsood , Parra Olguin Roberto , Perez-Martinez Ernesto , Rojas Figueroa Antonio
Published: September 2014

This paper investigates the use of CO2 as an EOR solvent for a heavy oil and high permeability naturally fractured reservoir complex in Mexico. The complex is under partial pressure maintenance by Nitrogen injection. First geological features and production performance are analyzed to discern peculiar pressure trends caused by natural depletion and N2 injection in order to establish the nature of prevailing fluid communication and identify a confined site for CO2 injection testing. An East Block in the North fields due to its unique dynamic faulting characteristics is found nearly compartmentalized to serve as a suitable site for CO2-EOR injection studies. Second, a finely-gridded dual permeability compositional simulation sector model with local grid refinement and boundary flux scheme is constructed and a calibrated 8-component EOS along with full tensor molecular diffusion is implemented to model CO2-EOR process mechanisms. CO2 and N2 injections into the gas cap at varying rates and huff-n-puff injection in the oil column are simulated. The impact of injection rate is illustrated, where injection of CO2 at low rates promotes diffusion and is shown to drain more of the matrix oil. The huff-n-puff simulation cases also indicate increased oil recovery and reduced matrix oil saturation by CO2 injection as compared with N2 injection due to a combination of oil swelling, reduced oil viscosity and partial miscibility with CO2. The paper concludes that the efficiency of CO2 injections is more pronounced at higher reservoir pressures and with no or less volumes of prior injected N2.
Methodology for Determination of Critical Water Saturation According to Pore-Throat-Size Analysis Using Capillary Pressure Made in Core Samples
Authors: Villarroel Atahualpa
Published: September 2014

The operating plan generation of a reservoir is based on an effective dynamic characterization for recovery of reserves. To achieve this goal we must prepare, the model describes the interaction between the rock and the fluids present in the reservoir, as well as contributing to the achievement of the original reserves in place, facilitates the reproduction of the behavior of a reservoir to be undergone some enhanced recovery process. For this reason it was necessary to develop a methodology for determination of critical water saturation according to the size of Throat Poral by capillary pressure analysis performed on core samples of the fields belonging to developed areas of the Orinoco Oil Belt.

In this study we propose a methodology that combined with the little information that may exist in a specific area leads to a better use of that information as a representative model of the entire stratigraphic column.

These results can then be used as input for reservoir simulation models belonging to these fields, allowing the representation of heterogeneity present in the same anisotropy obtaining a representative distribution of the fluids and with this a more accurate estimation of reserves hydrocarbons and their movement within the reservoir, and generating operating plans with excellent results in the estimated potential wells.

In this case the method used yielded a correlation of critical water saturation as a function of pore throat radius, with an adjustment of 90% with respect to laboratory measurements.
Assisted Extra Heavy Oil Sampling by Electromagnetic Heating
Authors: Bermúdez J.. , Acosta W.. , Andarcia L.. , Suarez A.. , Vaca P.. , Pasalic D.. , Okoniewski M..
Published: September 2014

Sampling extra heavy oil becomes a challenging operation when viscosities overcome 3000 cp at reservoir temperature. The acquisition of quality samples that allow obtaining accurate viscosity measurements and initial solution gas, among other fluid characterization measurements, is crucial, since they are key parameters to identify and select reservoir strategies. Samples that are commonly gathered from such reservoirs come from mud tanks during drilling, which bring uncertainty due to chemical contamination, and from preserved cores, which usually cannot provide sufficient volume for the required analysis.

A new sampling technique presented in this paper, involves an operation assisted by electromagnetic heating. This technology has been studied since the 70s, with some field trials in the 90s, and is currently subject of renewed interest due to better design and prediction methods. It consists of applying radiofrequency heating through use of an antenna positioned in front of the zone of interest. The target zone heats up due to the water molecules oscillation induced by the electromagnetic waves. The increment of reservoir temperature reduces the extra heavy oil (EHO) viscosity and allows such viscous fluid to flow. After heating a substantial fluid volume, the downhole sampling operation with a wireline tool can be started. Heated volume and temperature increment become key parameters to have a successful operation.

The heating process is simulated using a coupled reservoir and electromagnetic (EM) simulator. The thermal and electromagnetic models are created for a reservoir with standard conditions found in Colombian Llanos basin, which is the type of reservoir where this heating technology will be applied. Multiple simulations of the heating process using different radio frecuencies (RF) power levels, frequencies and antenna lengths were performed to identify the optimum combination which would allow fastest heating process.
Well Testing Characterization of Heavy-Oil Naturally Fractured Vuggy Reservoirs
Authors: Camacho-V. Rodolfo , Gómez Susana , Vásquez-C. Mario , Fuenleal-M. Norma , Castillo-R. Tomás , Ramos Gustavo , Minutti M. Carlos , Mesejo Alejandro , Fuentes-C. Gorgonio
Published: September 2014

This paper presents the advances on the characterization of Naturally Fractured Vuggy Reservoirs (NFVR) located in the South East Gulf of Mexico. Halos, fractures and vugs were characterized through well tests using the triple porosity–double permeability (3φ-2k) model. Through the analysis of well and imagelogs was determined the predominance of high vuggyporosity producing intervals, so that the pressure data were analyzed using a triple porosity-double permeability (3φ -2k) approach, with total and partial penetration. These NFVRs have vuggy and fracture porosity, with triple porosity, matrix, fractures, and vugs, or matrix, vugs with their halos. In both cases, the 3φ-2k model is appropriate to characterize these fields. These models, recently presented involve the determination of 9 and 13 parameters, for total and partial penetration, respectively, which implies challenges in terms of the uniqueness of the results. In this way, it is suggested to consider information from other sources like cores, well logs, and image logs, in order to select characteristic values for some of the parameters of the model of interpretation, specifically the storage ratios for vugs and fractures, ωv and ωf, and in this way to eliminate the non-uniqueness problem. Thus, the integration of static and dynamic information is a key element for a complete description of NFVR.

The 3φ-2k model allows better data fits than the classical dual-porosity model, obtaining more information related to the interactions of the three different media. The sum of vuggy and fracture porosity obtained from 3φ-2k model is not equal to the secondary porosity obtained from the dual-porosity model.

If partial penetration effects are present, it is recommended to perform the analysis taking into account these effects because information on the vertical communication of vugs and fractures can be obtained with the 3φ-2k model. It is confirmed through the analysis of well-tests with partial penetration that the vertical communication of vugs can be more important than the horizontal communication. It is crucial to obtain fracture and vug connectivity in both horizontal and vertical direction, mainly because these reservoirs are sharing a common aquifer.

The objective of this work is to demonstrate the application of a 3φ-2k model to determine several parameters related to reserves and productivity of NFVR. Vertical connectivity of both vugs and fractures are important parameters when an aquifer is underlying heavy oil NFVR, because these areas could establish preferential routes for the advancement of water.
Transient Shape Factors for Thermal Flow Simulation in Naturally Fractured Reservoirs: A Concept
Authors: Taabbodi L.. , Chen Z.. , Geiger S..
Published: September 2014

A significant number of naturally fractured reservoirs (NFRs) discovered in the world contain heavy and extra heavy oil. These reservoirs are important resources; however, the nature of naturally fractured reservoirs, especially those containing heavy and extra heavy oil, presents many unique and complex challenges for reservoir modeling and simulation. There have been a number of attempts over the last 50 years to develop methods to improve our understanding as to how the fracture systems impact oil recovery. For many decades, the dual-porosity approach has been the most popular and effective technique in modeling of NFRs. This approach separates the fracture and matrix systems into two different continua, each with its own set of properties. Fluid exchange between matrix and fractures is modeled through a Transfer Function (TF), while a shape factor describes the fracture-matrix surface area. However, the fracture-matrix fluid interaction is not yet fully understood for thermal processes, which represents a significant unknown in thermal reservoir simulation of NFRs containing (ultra) heavy oil.

In this paper an extensive literature survey was initiated to establish a detailed understanding as to how shape factors are utilized for modeling non-isothermal, fracture-matrix fluid exchange in fractured reservoirs. The most appropriate way is to treat the shape factor as a time-dependent quantity to capture the pertinent features of non-isothermal fluid flow in fractured reservoirs. A series of numerical simulations have been conducted using the simulator STARS from Computer Modeling Group Ltd. in order to analyze the performance of existing transfer functions and shape factor formulations for dual-porosity, multiphase flow systems in thermal reservoir simulation. Based on this analysis, we introduce the concept of a new, transient shape factor for non-isothermal, dual-porosity models and compare our new concept with the existing shape factor models. The results from this study clearly confirm that a transient shape factor is required for an appropriate modeling of a thermal recovery process in NFRs when using dual-porosity formulations.
Design and Construction of an Electrostatic Generator in an Experimental Test Bench, to Inhibit the Precipitation of Paraffinic Waxes
Authors: Jiménez C. C. , Campo B.. , Arias M.. , Vargas H.. , Ariza E..
Published: September 2014

The present article describes the design and construction of a device able of establishing an electrostatic field parallel to a flux of a liquid into a pipe. The generator device bases its operation on a flat parallel plate configuration under a voltage. The model E=V/d used to describe the electrostatic behavior is validated in two different ways: the first one is a lab experience and the second one through a simulation run. In the lab experience are gotten (in an indirect way) the electrostatic field magnitude and the liquid's electrical permittivity. Through the simulation run and the experimental permittivity value, is estimated, besides the intensity, the geometrical disposition of the generated field. It's validated an operation rank for the electrostatic field intensity between 0 and 1 [kV/mm]. The recommended rank for distance between the plates is from 5 to 14 [mm]. For an oil pump with a caudal between 5 and 55 [l/min], the time exposure is between 10,71 and 329,1[ms].
Heavy-Oil Waterflooding: Back to the Future
Authors: Alvarez J. M. , Sawatzky R. P. , Moreno R..
Published: September 2014

Waterflooding of conventional oil fields has been going on since the dawn of oil and gas production. In the 1940s and '50s, researchers in the oil community undertook a successful effort to understand the mechanisms underlying waterflooding, in order to improve its application. One of their findings was that as the mobility ratio increases the breakthrough time decreases exponentially. Furthermore, at high mobility ratios (> 500), the recovery factor does not increase much after breakthrough even after further water injection. Despite this conventional wisdom about waterflooding, it is gaining popularity around the world as a potential technology for recovering heavy oil. For example, in western Canada heavy oil reservoirs with a dead oil viscosity of up to 2,000 mPa.s have been targeted for waterfloods. Some surprising results, which appear to be at odds with conventional theory, include: extended periods of oil production at very high water cuts; and, much higher recovery factors than could be predicted from conventional theory. Mechanisms that have been proposed include: pressure support; unstable displacement and creation of water channels; water imbibition from those channels; viscous drag; emulsification; solution gas drive; apparent swelling of the oil; increasing gas saturations in the water channel causing a reduction in the water relative permeability; and, fracturing. Unfortunately, the speculation about the potential mechanisms involved in heavy oil waterflooding has not yet coalesced into a more tangible understanding of the role of each mechanism and the interplay between them. The relative importance of the mechanisms involved in heavy oil waterflooding, and the capability to enhance them at different stages in the operational life cycle of the waterflooding process, may provide a key to improving the recovery factors in heavy oil reservoirs that are being exploited by waterflooding. This paper will discuss the effort required to examine the mechanisms involved in heavy oil waterflooding, from an experimental perspective. It will address the different laboratory scales that can be employed to investigate these mechanisms, from the pore scale via micro-models to the semi-field scale using large experimental cells. Pathways incorporating these mechanisms in numerical models will be also discussed.
Novel Spotting Fluid to Handle Problems Associated With Differential Stuck Pipe in Heavy-Crude-Oil Reservoirs
Authors: Toro Carlos , Mesa Sebastian , Vergel Alfonso , Villalobos Mario , Orozco Diego , Charry German
Published: September 2014

Stuck pipe caused by differential sticking in horizontal wells is a problem that can result in the loss of tools in the hole, non-productive time (NPT), side tracks and even total loss of the well, with the consequence of significant cost increase for wellbore construction.

A differential pressure that pushes a drill string into the filter cake of a permeable formation causes differential sticking. It is typically remediated by pumping spotting fluids that are designed to break down the filter cake and reduce the bond between the filter cake and the pipe.

When drilling heavy crude oil reservoirs, conventional spotting fluids often fail to free the stuck pipe, because the filter cake is covered with heavy crude oil, which prevents the spotting pills from achieving good diffusion through the filter cake.

Additionally, these conventional spotting pills contain solids that cannot be easily removed from the production section when the well begins production.

Eventually, the solids would damage to the formations of interest. For this reason, a viable alternative was evaluated that could effectivety remove differential stuck pipe, and minimize potential formation damage.

To achieve this objective, a spotting fluid was formulated with a surfactant package that produces very low interfacial tension, enables high oil-cleaning capacity and easily removes heavy crude oil. This formulation is a solid-free fluid, formulated without acid. The mechanism to eliminate the bond between the pipe and filter cake is a diffusion process and solubilization of the heavy crude oil into the microemulsion, leaving the filter cake very porous, achieving quick release of the stuck pipe string. The fluid is mixed at the rig, using conventional equipment, and pumped downhole using standars rig pumps.

This paper discusses the use and operational procedures for application of this novel spotting fluid for cases of differential sticking occurring while drilling heavy crude oil reservoirs. Currently, the new spotting fluid has been applied in eight wells, with successful release of differential sticking in the reservoir zones during drilling of horizontal sections.
A Successful Gravel-Packing Technique in Vertical and Deviated Wells with Enlarged Open Hole in Cased Completions: A Case Study, Rubiales and Quifa Fields
Authors: Florez A.. , Osorio M..
Published: September 2014

Rubiales and Quifa fields are the major oilfield in Colombia; two heavy oil reservoirs (API in the range 11.3° to 14.4°) with unconsolidated sandstone formation with high permeability, however, there is low productivity in vertical and deviated wells, caused by formation damage from drilling fluids, and cased gravel packing completion.

These two formation damages have been mitigated by applying a successful gravel packing technique in both vertical and deviated wells. On June 30, 2014, the oil production rate was 186 thousand BOPD, of which 14.5 thousand BOPD (7%) came from 162 vertical and deviated wells with the successful gravel packing technique.

The successful gravel packing technique consists on first running a standard cemented 7 inches casing and then cutting the casing in the production zone and enlarge the open hole section from 8.5 inches to 13 or 16 inches diameter to remove cement bond overpassing the washout. Finally, the enlarged open hole section is gravel packed with mesh 20-40.

The completion technology purpose is to increase the well productivity, isolating high water saturation intervals on both top and bottom of the oil zone, reducing the skin damage.

Before 2007, 30 wells were completed with conventional cased hole gravel packing. Most of these wells were damaged having to be frequently stimulated with organic treatment; 14 of these wells have been re-completed using gravel packing technique. The results show an increase in the productivity index from 2 to 5 times, compared to conventional completion and showing a maximum increase in total fluid rate from 600 BFPD to 3000 BFPD.

Finally, some examples are presented comparing gravel packing using this technique and the cased hole completion method. Operation procedures, advantages, limitations, and production results are presented in individual well performance comparisons. The successful application of this technology has contributed to increase oil production in Rubiales and Quifa fields development and it has also been extended to others analogues fields.
Analytical Prediction Model of Sand Production Integrating Geomechanics for Open Hole and Cased – Perforated Wells
Authors: Araujo E. F , Alzate-Espinosa G. A , Arbeláez-Londoño A.. , Peña Clavijo S.. , Cardona Ramirez A.. , Naranjo Agudelo A..
Published: September 2014

Sand production treatment, control and mitigation generate high costs for the petroleum industry. Therefore, this is considered a critical problem and requires a continuous monitoring and special management. A sand production study is fundamental in field development and will help to eliminate or mitigate the related problems. This way, an analytical geomechanical sand production model is proposed to design the best field sand free production plan and to select the type of sand control measures and sand management techniques. The model needs as input data, the reservoir characteristicsn and a mechanical earth model derived from well logs that includes the stress state regime. It also requires the well direction, azimuth and completion information in order to evaluate the well characteristics. In this model an onset sand production condition is calculated looking for the borehole pressure that makes the maximum effective tangential compressive stress equal or higher than the rock strength (failure criteria), which is usually known as critical borehole pressure (CBHP). The results are presented on two kinds of graphs: the CBHP versus depth graph that allows determining the sand production free interval and the CBHP versus reservoir pressure graph that helps to design different well production plans for optimizing the recovered volume avoiding sand production. Results must be calibrated and verified with data field to simulate the real reservoir behavior. Briefly, for a specific well path it is possible to propose the operating CBHP as a function of the reservoir depletion and well completion (open or cased hole), also for a new well, it is possible to design the best well direction and the completion type, in addition to the operating CBHP to minimize sand production.
Assessment of Thermal Recovery: Steam Assisted Gravity Drainage (SAGD) to Improve Recovery Efficiency in the Heavy-Oil Fields of the Peruvian Jungle
Authors: Chun Nestor Antonio
Published: September 2014

The decline of medium and light oil production of most of the fields in Peru in the last years, the increase of the domestic demand, the rising of oil prices and the recent discoveries of large heavy oil resources in the Marañon Basin, makes the suitable scenario to economically develop such heavy oil reservoirs. The technical recoverable volumes estimated for heavy oil fields in Peru (with API degree of 12 or even less) represent a significant energy resource for the country. Reasons for applying SAGD process to improve recovery factor in these fields.

Cold production technologies in heavy oil fields with API degree of 12 or even less, yielded low recovery factors (no more than 15%). The fluid property that most affects the productivity and recovery of heavy crude oil is viscosity; therefore, it is expected that thermal process like SAGD would increase the recovery efficiency of heavy oil fields by adding heat.

An screening criteria matrix was prepared based on worldwide analogous projects, which includes the fluid and rock properties to apply in Heavy Oil Fields of the Peruvian Jungle; then, a conceptual local-grid refined simulation model was built to evaluate production performance and estimate a recovery factor for the zone. The SAGD process was compared in performance to conventional cold production methods of the region (deviated and horizontal wells with ESP pumps).

As a result, a matrix with recovery factors of SAGD process is provided; which with an average recovery factor of 25% looks very promising for a feasibility study.

With the success of SAGD process in analogous heavy oil fields around the world, this study aims to bridge the gap that Peru has in Thermal Recovery and EOR processes, with Screening matrix and Reservoir Simulation of SAGD process to apply a pilot program, increasing the national production.
Unlocking the Potential of a Mature Heavy Oil Field Using Innovative Well Placement Technology: A Case Study from Offshore China
Authors: Nie Chaomin , Jia Yong , Hu Yong , Bie Xuwei , Yang Liuhe , Zhai Gang , Su Jinchang , Wang Fei , Kok Jeffrey , Xu Chonghui , Gao Zhujun , Li Shuzhong , Wu Kai , Yu Xiaoning , Xu Tianyun
Published: September 2014

The Qing Huang Dao oilfield, located in the Bohai Bay has been in production for more than 10 years. To achieve production targets, many directional wells and horizontal wells were initially drilled with conventional tools and measurements. However, at the end of 2012, as the oilfield matures, the field's average water cut had reached a high of 86.4%.

Following a multidisciplinary study on bypassed oil distribution in this field, a new horizontal well drilling program was launched in 2012. The study team highlighted challenges in identifying the oil water contact (OWC) while placing the trajectory within a very small target window close to the roof that the program needs to be overcome. Off a detailed technology review, advance azimuthal LWD, with the ability to map the distance to the multiple boundaries such as the OWC, the top and bottom of the reservoir structure in the remaining oil column, was selected as the fit-for-purpose application and to enhanced reservoir understanding. In combination, rotary steerable drilling system (RSS) was selected to improve drilling efficiency and deliver smooth trajectory control.

This new approach using innovative azimuthal LWD technology implementation proved value in its utility by achieving the ultimate objective of drilling productive horizontal wells in QHD oilfield. The application reduced drilling cost, avoided unnecessary trajectory adjustments and kept the lateral trajectory within a very small target window of 1m to 1.5m close to the reservoir cap. Production from these horizontal wells surpassed production by 31% with only 4% water cut. The integrated solution of innovative LWD, well placement and RSS optimized this mature oilfiled development. The authors believe this approach and techniques could effectively address other similar mature oilfields development.
Differential Cased-Hole Shear Anisotropy DCHSA Methodology as a Calibration and Evaluation Tool of Hydraulic Fracture Height in Colombian Fields
Authors: Santamaria Jose Camilo , Velez Edgar , Bahamon Jorge
Published: September 2014

Due to specific reservoir features such as high skin levels and poor petrophysical properties, a common activity applied in order to reduce skin levels, and increase well productivity index, is hydraulic fracturing operation; this formation stimulation activity, use generation of preferential channels of high conductivity, in order to improve these reservoir features.

Mechanical properties play a relevant role, during a successful fracturing job, planning and execution. Geomechanical parameters are valuable information, in order to select the most convenient intervals, to perform the fracturing job, and estimate the theoretical fracturing height results. Additional tools are essential in order to evaluate hydraulic fracture effectiveness; these tools will provide important information, related to fracture height, containment and complexity.

This paper presents the application of differential cased hole shear anisotropy (DCHSA) methodology, in Chichimene and Castilla Colombian fields, where hydraulic fracture height was determined, based on acoustic logs information. By determining hydraulic fracture height, mechanical barriers can be identified, in some cases these barriers can be acting containing the fracture growth, and planning of following fracture jobs, can be optimized along field. Using differential cased hole shear anisotropy (DCHSA) methodology, a better understanding of post stimulation production results can be obtained, this information helps to reach better calibration of existing geomechanical model, and fracture design can be optimized, in order to improve fracturing planning, for better well production and field development optimization.
Investigation of Orifice Type Flow-Control Device Properties on the SAGD Process Using Coupled Wellbore Reservoir Modeling
Authors: Noroozi Mehdi , Melo Marco , Singbeil R.P.(Pete). P.(Pete) , Neil Blair
Published: September 2014

In order to optimize production of a SAGD process many strategies have been adopted. These strategies may include; a Dual-Tubing completion which contains short and long tubing strings to inject steam in to the reservoir, Proportional-Integral-Derivative (PID) to control steam injection, flow control devices (FCDs), and others. In all these methods; operators try to maximize ultimate recovery by increasing thermal communication between well pairs, enhancing steam conformance, and improving oil displacement efficiency. Currently flow control devices (FCDs) are widely used in thermal operations. This tool can be installed on both production and injection wells in a SAGD well pair. The FCD tool in an injection well is also known as a steam splitter, which gives the operator the opportunity to target sections of the wellbore to receive steam. In a production well, FCDs are used to develop a uniform inflow along the horizontal section of the wellbore. This helps in managing the interface between the injection and production wells to maximize the productivity. The effects of orifice type FCD properties on a SAGD process have not yet been investigated. These properties include port (orifice) size and port quantities. Locations of FCDs in both injector and producer are another important parameter that needs to be addressed and optimized in a SAGD operation. This paper investigates the impact of each of these FCDs properties along with the location of FCDs on a SAGD process through coupled wellbore-reservoir modeling. In addition; a detailed study is carried out to present a workflow for the FCD optimization that can help engineers to design FCDs in both injector and producer in a SAGD well pair.
Treatment of Water in Heavy Crude Oil Emulsions with Innovative Microemulsion Fluids
Authors: Pietrangeli Gianna , Quintero Lirio , Jones Thomas , Darugar Q..
Published: September 2014

In-situ formation of water-in-oil emulsions in crude oil is one of the severe problems encountered during the production phase of oil wells. These in-situ emulsions produce crude oil viscosities that are much higher than the viscosities of native crude oil. It is well known that these problems are frequently found in heavy and extra-heavy crude oils, because these oils have significant amounts of carboxylates and naphthenates, which are polar molecules that are excellent stabilizers of water-in-crude oil emulsions.

These in-situ emulsions form in the reservoir and in the near-wellbore regions. However, when the crude oil is produced to surface, they may also develop at various downstream locations such as at wellheads, pipelines, separation plants, and even at the refinery before processing. The major factors that determine the formation of in-situ emulsions are the crude oil/produced water ratio, properties and composition of the crude oil and connate water, and some reservoir properties such as temperature. Demulsifiers are traditionally used to prevent the formation of in-situ emulsions. These treatments are generally effective. In situations where the demulsifier chemistry cannot change the curvature of the oil/water interface, the emulsification problem persists, with inherent consequences such as loss of production, high-pressure drops in flow lines and increased operational costs.

A solution to treat these troublesome emulsions is to use microemulsion fluids technology. Microemulsion fluids typically have very low oil/water interfacial tension and can alter the interfacial curvature of the emulsion, producing coalescence and increasing water droplet size until the emulsion separates into water and crude oil.

This paper discusses the evaluation of microemulsion fluids as a treatment for emulsified heavy crude oil samples from oil fields. The evaluation includes crude oil characterization, interfacial tension, microscopy evaluation, fluids compatibility tests and treatment of the emulsion in an HPHT filtration cell.
Radiographic assessment of lower third molar eruption in different anteroposterior skeletal patterns and age-related groups
Authors: Jakovljevic Aleksandar , Lazic Emira , Soldatovic Ivan , Nedeljkovic Nenad , Andric Miroslav
Published: September 2014

Objective: 

To analyze radiographic predictors for lower third molar eruption among subjects with different anteroposterior skeletal relations and of different age groups.

Materials and Methods: 

In total, 300 lower third molars were recorded on diagnostic digital orthopantomograms (DPTs) and lateral cephalograms (LCs). The radiographs were grouped according to sagittal intermaxillary angle (ANB), subject age, and level of lower third molar eruption. The DPT was used to analyze retromolar space, mesiodistal crown width, space/width ratio, third and second molar angulation (α, γ), third molar inclination (β), and gonion angle. The LC was used to determine ANB, angles of maxillar and mandibular prognathism (SNA, SNB), mandibular plane angle (SN/MP), and mandibular lengths. A logistic regression model was created using the statistically significant predictors.

Results: 

The logistic regression analysis revealed a statistically significant impact of β angle and distance between gonion and gnathion (Go-Gn) on the level of lower third molar eruption (P < .001 and P < .015, respectively). The retromolar space was significantly increased in the adult subgroup for all skeletal classes. The lower third molar impaction rate was significantly higher in the adult subgroup with the Class II (62.3%) compared with Class III subjects (31.7%; P < .013).

Conclusion: 

The most favorable values of linear and angular predictors of mandibular third molar eruption were measured in Class III subjects. For valid estimation of mandibular third molar eruption, certain linear and angular measures (β angle, Go-Gn), as well as the size of the retromolar space, need to be considered.
Chinese Version of the Responses to Positive Affect Questionnaire: Testing the Factor Structure, Reliability, and Validity in a College Student Sample
Authors: Yang Hongfei , Guo Wenjing
Published: September 2014

This study tested the psychometrics of the Chinese version of the Responses to Positive Affect Questionnaire among 915 Chinese college students with an average age of 20.3 yr. ( SD = 1.6). The original three-factor model with the factors dampening, emotion-focused positive rumination, and self-focused rumination was supported using exploratory and confirmatory factor analyses. All subscales showed good internal reliability, as well as evidence for convergent and incremental validity with measures of ego-resiliency, life satisfaction, and mental health symptoms. Finally, a series of hierarchical regression analyses indicated that the three subscales, especially dampening, accounted for additional unique variance in psychological adjustment above and beyond resilience. These findings generally suggested that the Chinese Responses to Positive Affect Questionnaire possesses acceptable psychometric properties. Implications for counseling, limitations, and suggestions for future study were presented.
Fuzzy ranking based non-dominated sorting genetic algorithm-II for network overload alleviation
Authors: Pandiarajan K. , Babulal C.K.
Published: September 2014

This paper presents an effective method of network overload management in power systems. The three competing objectives 1) generation cost 2) transmission line overload and 3) real power loss are optimized to provide pareto-optimal solutions. A fuzzy ranking based non-dominated sorting genetic algorithm-II (NSGA-II) is used to solve this complex nonlinear optimization problem. The minimization of competing objectives is done by generation rescheduling. Fuzzy ranking method is employed to extract the best compromise solution out of the available non-dominated solutions depending upon its highest rank. N-1 contingency analysis is carried out to identify the most severe lines and those lines are selected for outage. The effectiveness of the proposed approach is demonstrated for different contingency cases in IEEE 30 and IEEE 118 bus systems with smooth cost functions and their results are compared with other single objective evolutionary algorithms like Particle swarm optimization (PSO) and Differential evolution (DE). Simulation results show the effectiveness of the proposed approach to generate well distributed pareto-optimal non-dominated solutions of multi-objective problem
Novel ultrasonic distance measuring system based on correlation method
Authors: Gądek K. , Jaraczewski M.
Published: September 2014

This paper presents an innovative method for measuring the time delay of ultrasonic waves. Pulse methods used in the previous studies was characterized by latency. The method of phase correlation, presented in this article is free from this disadvantages. Due to the phase encoding with the use of Walsh functions the presented method allows to obtain better precision than previous methods. The algorithm to measure delay of the reflected wave with the use of microprocessor ARM Cortex M4 linked to a PC has been worked out and tested. This method uses the signal from the ultrasonic probe to precisely determine the time delay, caused by the propagation in medium, possible. In order to verify the effectiveness of the method a part of the measuring system was implemented in LabVIEW. The presented method proved to be effective, as it is shown in presented simulation results
Flywheel energy storage control system with the system operating status control via the Internet
Authors: Baszyński Marcin , Siostrzonek Tomasz
Published: September 2014

Modern electronics systems consist of not only with the power electronics converters, but also with the friendly user interface which allow you to read the operating parameters and change them. The simplest solution of the user interface is to use alphanumeric display which displays information about the state of the converter. With a few additional buttons you can change the settings. This solution is simple, inexpensive but allows only local control (within walking distance from the system) and the number of displayed information is low. You can create extensive menu, but it causes problems with access to information. This paper presents the example of a rotating energy storage universal solution which is lack of the above mentioned disadvantages
Influence of magnetic saturation effects on the fault detection of induction motors
Authors: Drozdowski Piotr , Duda Arkadiusz
Published: September 2014

In this paper, the influence of impact damage to the induction motors on the zero-sequence voltage and its spectrum is presented. The signals detecting the damages result from a detailed analysis of the formula describing this voltage component which is induced in the stator windings due to core magnetic saturation and the discrete displacement of windings. Its course is affected by the operation of both the stator and the rotor. Other fault detection methods, are known and widely applied by analysing the spectrum of stator currents. The presented method may be a complement to other methods because of the ease of measurements of the zero voltage for star connected motors. Additionally, for converter fed motors the zero sequence voltage eliminates higher time harmonics displaced by 120 degrees. The results of the method application are presented through measurements and explained by the use of a mathematical model of the slip-ring induction motor
Comparison of Different Measurement Variables Based on Hungarian Show Jumping Results
Authors: Mezei Anita Rudiné , Posta János , Mihók Sándor
Published: September 2014

The aim of the study was to find a possible way to measure the performance of sport horses based on their show jumping results and to estimate the heritability and repeatability values of these performances. The performance was measured with transformation of ranks, taking into account the number of starters at competition and the competition level. The used transformations were logarithmic, square root and an inverse normal transformation known as Blom method. Competitions were categorized into five groups based on their level of difficulty. The level of difficulty of the competitions was used as weighting factors, so performance traits were distinguished being weighted and non-weighted. Show jumping competition results collected between 1996 and 2011 were analysed. The database contained 358342 starts of 10199 horses. Identity number, name and gender of the horse, rider, competition year, the level and location of the competition and ranks were recorded in the database. The used repeatability animal model included fixed effects for age, gender, competition place, year of competition, and random effects for rider, animal and permanent environment effect. Variance components were estimated with VCE-6 software package. The goodness-of-fit of the models was low and moderate (0.09-0.47). Fitting models for weighted traits had better goodness-of-fit value. The best goodness-of-fit values were found in the case of level weighted variables. Heritability (0.02-0.07) and repeatability values (0.09-0.25) were low for each measurement variable.