bluuebunny/crossref_metadata_2025 huggingface dataset:
PRESCHOOLERS' COMPLIANCE WITH SIMPLE INSTRUCTIONS: A DESCRIPTIVE AND EXPERIMENTAL EVALUATION
Authors: Stephenson Kasey M. , Hanley Gregory P.
Published: December 2010

Compliance is often used to describe a situation in which a child completes instructions from adults, and low levels of compliance are a common teacher concern. We conducted a descriptive assessment that showed that compliance was relatively stable for individual children, variable across children, and positively correlated with age. The impact of six antecedent variables (proximity, position, physical contact, eye contact, vocal attention, and play interruption) on compliance was assessed for 4 children. Next, the effects of three‐step prompting were assessed alone, in combination with the antecedent variables, and at different integrity levels for 2 children. Results of the experimental analyses showed that compliance gradually increased with the addition of each antecedent variable for 2 of the 4 children. Three‐step prompting in combination with the six antecedent variables increased compliance for the remaining 2 children, and high compliance levels were maintained until treatment integrity was decreased to 20% of full strength. The utility of this naturalistic compliance assessment is discussed, as are the relevant experiences that give rise to acceptable levels of compliance in preschool classrooms.
TEMPORAL PATTERNS OF BEHAVIOR FROM THE SCHEDULING OF PSYCHOLOGY QUIZZES
Authors: Jarmolowicz David P. , Hayashi Yusuke , Pipkin Claire St. Peter
Published: December 2010

Temporal patterns of behavior have been observed in real‐life performances such as bill passing in the U.S. Congress, in‐class studying, and quiz taking. However, the practical utility of understanding these patterns has not been evaluated. The current study demonstrated the presence of temporal patterns of quiz taking in a university‐level introductory psychology course and used these patterns to manage the traffic of quiz takers in a computerized testing lab. Results are discussed in terms of the applications of tracking temporal response patterns.
EVALUATION OF COMBINED‐ANTECEDENT VARIABLES ON FUNCTIONAL ANALYSIS RESULTS AND TREATMENT OF PROBLEM BEHAVIOR IN A SCHOOL SETTING
Authors: Dolezal Danielle N. , Kurtz Patricia F.
Published: December 2010

Call, Wacker, Ringdahl, and Boelter (2005) conducted an analysis in which a single‐antecedent condition was compared to a multiple‐antecedent condition. The present study extended Call et al. by conducting a structured descriptive assessment (SDA) to identify the antecedent variables most associated with problem behavior in a student with traumatic brain injury and intellectual disabilities. Results indicated that the SDA was effective in identifying relevant antecedent variables that led to the development of an effective intervention in the classroom.
A REVIEW OF RECENT STUDIES ON DIFFERENTIAL REINFORCEMENT DURING SKILL ACQUISITION IN EARLY INTERVENTION
Authors: Vladescu Jason C. , Kodak Tiffany
Published: December 2010

Although the use of differential reinforcement has been recommended in previous investigations and in early intervention curriculum manuals, few studies have evaluated the best method for providing differential reinforcement to maximize independent responding. This paper reviews previous research on the effectiveness of differential reinforcement as treatment and describes important areas of future research.
NEUROBEHAVIORAL EVIDENCE FOR THE “NEAR‐MISS” EFFECT IN PATHOLOGICAL GAMBLERS
Authors: Habib Reza , Dixon Mark R.
Published: December 2010

The purpose of this translational study was twofold: (1) to contrast behavioral and brain activity between pathological and nonpathological gamblers, and (2) to examine differences as a function of the outcome of the spin of a slot machine, focusing predominately on the “Near‐Miss”—when two reels stop on the same symbol, and that symbol is just above or below the payoff line on the third reel. Twenty‐two participants (11 nonpathological; 11 pathological) completed the study by rating the closeness of various outcomes of slot machine displays (wins, losses, and near‐misses) to a win. No behavioral differences were observed between groups of participants, however, differences in brain activity were found in the left midbrain, near the substantia nigra and ventral tegmental area (SN / VTA). Near‐miss outcomes uniquely activated brain regions associated with wins for the pathological gamblers and regions associated with losses for the nonpathological gamblers. Thus, near‐miss outcomes on slot machines may contain both functional and neurological properties of wins for pathological gamblers. Such a translational approach to the study of gambling behavior may be considered an example that gives life to B. F. Skinner's conceptualization of the physiologist of the future.
SEMANTIC FALSE MEMORIES IN THE FORM OF DERIVED RELATIONAL INTRUSIONS FOLLOWING TRAINING
Authors: Guinther Paul M. , Dougher Michael J.
Published: December 2010

Contemporary behavior analytic research is making headway in characterizing memory phenomena that typically have been characterized by cognitive models, and the current study extends this development by producing “false memories” in the form of functional equivalence responding. A match‐to‐sample training procedure was administered in order to encourage participants to treat groups of unrelated English words as being interchangeable. Following training, participants were presented with a list of words from within one of the groups for a free recall test and a recognition test. Results showed that participants were more likely to falsely recall and recognize words that had been assigned to the same group as the list words during prior training, relative to words not assigned to the same group and relative to words that co‐occurred with list words. These results indicate that semantic relatedness can be experimentally manipulated in order to produce specific false memories.
DIFFERENTIAL REINFORCEMENT OF ALTERNATIVE BEHAVIOR INCREASES RESISTANCE TO EXTINCTION: CLINICAL DEMONSTRATION, ANIMAL MODELING, AND CLINICAL TEST OF ONE SOLUTION
Authors: Mace F. Charles , McComas Jennifer J. , Mauro Benjamin C. , Progar Patrick R. , Taylor Bridget , Ervin Ruth , Zangrillo Amanda N.
Published: December 2010

Basic research with pigeons on behavioral momentum suggests that differential reinforcement of alternative behavior (DRA) can increase the resistance of target behavior to change. This finding suggests that clinical applications of DRA may inadvertently increase the persistence of target behavior even as it decreases its frequency. We conducted three coordinated experiments to test whether DRA has persistence‐strengthening effects on clinically significant target behavior and then tested the effectiveness of a possible solution to this problem in both a nonhuman and clinical study. Experiment 1 compared resistance to extinction following baseline rates of reinforcement versus higher DRA rates of reinforcement in a clinical study. Resistance to extinction was substantially greater following DRA. Experiment 2 tested a rat model of a possible solution to this problem. Training an alternative response in a context without reinforcement of the target response circumvented the persistence‐strengthening effects of DRA. Experiment 3 translated the rat model into a novel clinical application of DRA. Training an alternative response with DRA in a separate context resulted in lower resistance to extinction than employing DRA in the context correlated with reinforcement of target behavior. The value of coordinated bidirectional translational research is discussed.
EVALUATION OF RESISTANCE TO CHANGE UNDER DIFFERENT DISRUPTER CONDITIONS IN CHILDREN WITH AUTISM AND SEVERE INTELLECTUAL DISABILITY
Authors: Lionello‐DeNolf Karen M. , Dube William V. , McIlvane William J.
Published: December 2010

Translational research inspired by behavioral momentum theory in the area of developmental disabilities has shown effects in individuals over a range of functioning levels. In the current study, behavioral momentum was assessed in 6 children diagnosed with autism and severe intellectual disability. In a repeated measures design, participants were exposed to relatively rich versus lean reinforcement contingencies in a multiple schedule with food reinforcers. This was followed by exposure to each of four disrupting conditions: prefeeding, presentation of a concurrent alternative stimulus, presentation of a movie, and the presence of a researcher dispensing response‐independent reinforcers on a variable‐time schedule. Consistently greater resistance to disruption in the component with the richer schedule occurred with the alternative stimulus disrupter but not with the other disrupters. These results suggest parameters that may be more (or less) effective if behavioral momentum inspired techniques are to be exploited in therapeutic environments.
A Novel Method to Identify Pore Fluid in Low Porosity/Low Permeability Gas Zones
Authors: Liu Xiao-peng , Hu Xiao-xin
Published: December 2010

Considering that it is difficult for well log analysts and geologists in identifying pore fluid in low porosity and low permeability reservoirs because of the variation of formation water salinity, a novel chart is proposed by using Archie equation to gain the lower limit of resistivity. This chart has considered the affection of formation water salinity and temperature to the resistivity, from this chart, it can be seen that for different formation porosity, different formation water salinity or temperature, the lower limit of resistivity for gas sand is different, the formation porosity is more bigger, formation water salinity is more higher and the reservoir temperature is more higher, the correspondent lower limit of resistivity for hydrocarbon reservoir is more little, vice versa. With this chart, it will be much easier in interpreting the appearance of high resistivity water layers or low resistivity hydrocarbon reservoir. It will also be usable in the interpretation of the formation that they are reconstructed and connected with the surface water thus lead to large diversity in formation water salinity between adjacent wells.
Uncertainty Analysis Considering the Production History: Evaluation of a Real Field
Authors: Lisboa E. , Duarte R.
Published: December 2010

The use of uncertainty analysis as a tool in reservoir studies is becoming more and more common inside Petrobras and all around the world. However, in fields with production history, traditional uncertainty analysis, combining possible values of uncertainty variables, can lead to models that poorly represent the reservoir and to results that do not respect the available dynamic data. During uncertainty analysis process, history matching evaluation can considerably reduce the existing uncertainties.

The methodology used in this work is based on experimental design and response surfaces. Besides the cumulative production response surface, another one is generated to represent the quality of the history matching. Only cases with a good history matching are selected as input to the Montecarlo simulation. With this technique, it is possible to evaluate the initially defined probability distributions and, if necessary, to redefine shape or limits for the probability density curve.

The methodology was applied in a real study in Petrobras. There are uncertainties related to faults, absolute permeability and also related to the existing fluid properties. Although there are other wells in the same block, the studied area is located in a sea-bottom slope region, where water depth varies considerably within the block, possibly influencing the oil quality.

Since there are two wells operating in the studied region, one producer and one injector, the developed analysis took the existing dynamic data into account, reducing model uncertainties.
Prediction of Bubblepoint Pressure and Bubblepoint Oil Formation Volume Factor in the Absence of PVT Analysis
Authors: Elmabrouk S. , Zekri A. , Shirif E.
Published: December 2010

Up till now, there has not been one specific correlation published to directly estimate the bubblepoint pressure in the absence of PVT analysis and, at the moment, there is just one published correlation available to estimate the bubblepoint oil FVF directly in the absence of PVT analysis. The majority of the published bubblepoint pressure and bubblepoint oil FVF correlations cannot be applied directly. This is because the correlations require the knowledge of bubblepoint solution GOR and gas specific gravity as part of the input variables, both of which are rarely measured field parameters. Solution GOR and gas specific gravity can be obtained either experimentally or estimated from correlations. In this study, multiple regression analysis technique is applied in order to develop two novel correlations with which to estimate the bubblepoint pressure and the bubblepoint oil FVF. These new correlations can be applied in a straightforward manner by using direct field data. Additional correlations or experimental analyses are unnecessary. Separator GOR, separator pressure, stock-tank oil gravity and reservoir temperature are the only key parameters required to predict bubblepoint pressure and bubblepoint oil FVF using the proposed correlations.
Performance Model Analysis for Candidate Recognition
Authors: Tan J. S. , Castillo Y. Del , Reese R. D. , Pinzon C.
Published: December 2010

The main objective of the project was to increase operation efficiency through monitoring production and injection performance in 18 Permian Basin fields (waterflood and natural depletion). A performance model (PM) technique has been developed to efficiently analyze massive amounts of production and injection data from thousands of wells. Using the PM technique, under- performing wells and patterns were rapidly identified and ranked for workover opportunities. Additionally, non-responsive injection areas (composed of several patterns) were also identified to enhance injection efficiency. The PM technique was implemented in 18 fields in the Permian Basin. The largest field having more than 1300 wells was evaluated.

The PM technique described here is based on a modified heterogeneity index (MHI) concept. This improvement was necessary since calculations using traditional heterogeneity index (HI) skewed the results and incorrectly quantified the performance comparison. The MHI has successfully corrected and overcome traditional HI weakness.

The PM is an improved candidate recognition technique that uses binary codes and personality concepts to effectively monitor wells and injection patterns. The personality characterization process creates and uses several interpretation scenarios to identify problematic wells, patterns or both.

PM methodology and personality concepts are discussed in detail and field implementation results are presented.
Integrated Monitoring of Radon and NORM Scale for HSE: Case Study of Well Surveillance
Authors: Nengkoda A. , Hajri M. , Kindy A. , Bulushi A. , Yazeedi Z. , Velagapudi R. Kiran
Published: December 2010

Processes of oil production, gathering, transportation are some times accompanied by scaling of radioactive materials (NORM). As an integrated approach to identify the Radon and NORM scale as flow assurance issue, a campaign of Radon monitoring, Barium and Strontium ion analysis from produced water potential lead to NORM scale have been conducted starting from well testing and in both onplot-offplot of the oil gathering station. Chemical composition of NORM scales strongly depend on chemical composition of produced waters. Presence of considerable amount of radioactive materials on technological equipment during production and treatment of oil, and gas may lead to personnel irradiation exceeding allowable levels and creates potential hazard to environmental pollution. The role of radon and its decay products in pollution of environment and internal personnel irradiation was not practically studied. Liberation of radon with decay products from scales and their entry into atmosphere may lead to radioactive pollution of environment, which increases the risk of internal personnel irradiation. This technical paper explained how to monitor effectively potential NORM and the intensity of radon accumulation in X field Petroleum Development Oman. During well testing or intervention, the equipment of wells radiobarite precipitates on impellers of electric centrifugal pumps, tubing inside surface in the form of white films with yellowish tint. Thickness of scales on tubing surface achieves 3 mm. In long-run operation radiobarite in electric centrifugal pump is able to clogging up. As a result of this well surveillance, Radon, Barium and Strontium analysis from produced water are really helpful in predicting NORM potential.
A New Approach for Gas Separation in Pumped Directional Wells
Authors: Ortiz Vidal L. E. , Rodriguez O. M.
Published: December 2010

This paper presents a new approach associated with the gas separation in inclined gas-liquid flow. This type of flow is found when gravitational gas separators are applied in association with the submergible centrifugal pump (SCP) technique for oil production in directional wells. Free gas in the suction of the SCP is one of the most important limitations in the design of the pumping system. The purpose of this study is the phenomenological modelling of total gas separation in a gravitational gas separator formed by an inclined annular channel whose geometry is known as inverted-shroud separator. Inclination angle, inlet and outlet gas mass flow rates, position of the dynamic level of liquid in the annular channel, casing pressure, and liquid flow rate are related to the separation efficiency. Bubble size is a key factor for the design of gravitational gas separators. Thus, a correlation for the two-phase turbulent kinetic energy dissipation, which has a significant effect on the bubble size, is proposed. New data were collected in an inclinable test section, at 15 and 45 degrees from the horizontal, with inside and outside diameters of 20 and 65 mm, respectively. The total length of the test section was 10.5 m. Air and water at near atmospheric pressure constituted the gas and liquid phases. The liquid flow rate was in the 9–26 l/min range and the average inlet gas mass flow rate was 1.18 kg/hr. The proposed model was qualitatively compared with data from the literature and quantitatively adjusted against the new experimental data, with good agreement. This new approach will assist in the optimization and sizing of the pumping system for oil production in directional wells.
Rapid Optimization of Development Scenarios for Multiple Exploration Prospects Using an Integrated Asset Model
Authors: Smyth John , Rusin Piotr , Garcia Jhairo , Cullick Stan
Published: December 2010

This paper introduces a decision optimization procedure that can evaluate and rank hundreds of prospect development scenarios quickly. Sophisticated optimization techniques that include uncertainty analysis are combined with fully coupled reservoir simulation models and a surface production network.

In an example, 12 prospects are evaluated together. Each prospect is multi-zone with varying physical parameters, where each prospect has an equal probability of success. This procedure represents a holistic approach that incorporates technical drilling constraints, full-cycle development costs, and economic evaluation. The methodology yields production profiles for a maximum of seven successes out of the 12 prospects. Production plateaus range from 5 to 20 years at rates ranging from 50,000 to 150,000 BOPD. More than 3,000 simulations, representing 60 development scenarios each covered by 64 uncertainty samples were executed for the integrated asset model. This method yields full-development cycle results and enables decision makers to screen potential projects quickly. This approach considers all possible scenarios under conditions of uncertainty to provide associated risks. The procedure can quickly be scaled from quite coarse subsurface models, e.g., "tanks", to higher-resolution models as new information is acquired.

We present a rigorous method for the rapid evaluation of a portfolio of exploration prospects to benefit operators who perform early pre-screening of projects in their current portfolios or who are considering new business opportunities that require rapid and accurate evaluation. Strategic tendencies are quickly identified and enable integrated asset teams to focus on critical aspects of potential project performance.
Drilling Optimization Using 3D Geomechanical Modeling in the Llanos Orientales Basin, Colombia
Authors: Araujo Ewerton , Alcalde Rene , Mateus Darwin , Fernandez-Ibañez Fermín , Sheridan Judith , Ward Chris , Brudy Martin , Alvarellos Jose , Ordonez Luz Yamile , Cardona Felipe
Published: December 2010

Drilling in tectonic active areas always faces NPT related to wellbore instability problems, which are very difficult to predict without a clear understanding of the local and regional stresses magnitude and orientation and their impact on any wellbore trajectory. Ecopetrol S.A. has experienced those problems in the Apiay-Suria areas in the Llanos Orientales basin over the last 20 years. In order to optimize the drilling process by eliminating the NPT related to wellbore instability, a 3D geomechanical model was built integrating the geological structural model with all relevant well information such as wireline logging data and drilling reports.

Data from more than 40 wells was used to build several 1D individual geomechanical models. To avoid missing local tectonic effects on the stress field, offset wells close to and away from the main faults crossing the fields were selected. To constrain the orientation and magnitude of the in situ stresses, image data was extensively analyzed to pick wellbore failure (breakouts and induced fractures) while drilling. Wireline logging was used as insightful information to calculate overburden, rock strength and to understand the pore pressure generation mechanism.

The 3D model was built using formation tops, faults geometry, reservoir pressure and hydraulic fracturing data. By applying geostatistical techniques on the individual wells’ 1D models, a 3D volume of stresses and rock properties was obtained. The comparison of the 3D results with real data measured in a recent well drilled at the edge of the 3D cube showed amazing one-to-one similarity in all the formations from the reservoir to surface. The new drilling campaign has started using the 3D model for wellbore stability analysis and the results are showing that the associated geomechanical risks to drill the wells in the area have been properly addressed, and a much better drilling experience has been obtained, taking out the guesswork from the process.
Effect of Mobile Water-Saturation on Thermal Efficiency of Steam-Assisted Gravity-Drainage Process
Authors: Javad S. , Oskouei P. , Maini B. , Moore R. G. , Mehta S. A.
Published: December 2010

The commercial viability of SAGD process is negatively affected by several undesirable reservoir features like pronounced heterogeneity, low vertical permeability, thick and areally extensive shale barriers and steam thief zones. The efficiency of SAGD projects is also affected by the presence of mobile water saturation in the target zone. Although the presence of small mobile water saturation is not considered harmful, reservoirs with high mobile water saturation may be poorly suited for the SAGD process. Nonetheless, SAGD remains the only practical technology for in situ extraction of oil from oil-sand reservoirs, even when mobile water is present. This raises the question of how much mobile water is a show stopper.

To investigate the effect of mobile water saturation on SAGD performance, high pressure physical model experiments were carried out. Different levels of mobile water saturations were established in the model by modifying the packing and saturating techniques. SAGD experiments were conducted by injecting superheated steam at controlled rates and producing the oil from the production well at constant pressure. The injection rate was selected to keep the pressure difference between the injector and producer at a low level.

The oil production behavior was analyzed to evaluate the effect of water saturation on the thermal efficiency of the process. Based on the results of low (immobile) and high (mobile) water saturation experiments it was observed that oil recovery factor droped by 7% and Cumulative Steam Oil Ratio increased by 50 percent when initial water saturation was increased from 14.7% to 32%.
Carbon Footprint and Principle of Additionality in CO2-EOR Projects: The Weyburn Case
Authors: Condor J. , Suebsiri J. , Wilson M. , Asghari K.
Published: December 2010

This paper addresses the process of using CO2 for enhanced oil recovery technique (CO2-EOR) as driver to produce more oil from depleted oil reservoirs, while leading to effective CO2 abatement. Here, a simplified summary of this complex system through a lifecycle emission analysis is presented. This analysis is based on two concepts: (i) the Carbon Footprint of CO2-EOR, and (ii) the Principle of Additionality in CO2-EOR. The data used for this analysis comes from the Weyburn project in Saskatchewan, Canada.

The international community has been discussing for some time if CO2-EOR projects should be considered for carbon credits. There are still questions of "additionality" that should be addressed before the net climate impact of storing CO2 in an EOR project is verified. Since CO2-EOR has gained considerable interest within the oil and gas industry due to its potential for increased oil production, it is important to use a real case data to probe if CO2-EOR is a viable CO2 abatement technology or if on the contrary, it may result in increased emissions.

This study concludes that any emissions trading benefits from CO2 storing as part of a CO2-EOR project should be discounted according to a detailed analysis of the full cycle carbon balance using the principle of additionality. A key exception to this should be when a commercially viable CO2-EOR project results in the development of pipeline infrastructure which would also enable long term geological sequestration without EOR. In this way, CO2-EOR projects could play an important catalyst role in accelerating the deployment of CCS infrastructure. Finally a sensitivity analysis has indicated that the provision of petroleum tax breaks for CO2-EOR projects on the grounds of their emissions reduction potential is not the best use of public funds.

This study provides guidance to whether or not CO2-EOR projects should be eligible for carbon credits as part of deployment of CCS processes. Also this study contributes by defining an appropriate framework for developing guidelines, standards, and/or best practice manuals for the permanent geological sequestration of carbon dioxide.
Gas Condensate Field Development Plan by Means of Numerical Compositional Simulation
Authors: Huerta V. A. , Lanchimba A. , Villagra L. , Chacon R. , Peru Repsol , Savoy E. , Colonomos P.
Published: December 2010

During the latest years, some gas condensate fields have been discovered in the Peruvian Amazonian rainforest. One of these fields is an anticline structure controlled by a reverse fault norwest – southeast; a wildcat well, drilled at the top, tested gas and condensate from NIA, NOI and ENE reservoirs; commercial decision on developing this gas condensate field will strongly depend on estimating its hydrocarbon potential.

Structural, rock-type, fluid-type and reservoir performance uncertainties are closely linked to 2D seismic grid and restricted information implicit to this exploratory well. A conceptual compositional simulation model was built for this gas-condensate field during its early stage to integrate seismic interpretation, petrophysical analysis, fluid behavior, and eventually, to come up with a reasonable estimation of resources, predict production performance and visualize development options.

Structural uncertainties were addressed by testing some geology maps, which were prepared with different velocity models for time to depth conversion. In addition, rock properties were sensitized with multiple deterministic and probabilistic executions taking into account ranges and cut offs of analogous fields. The fluid was characterized by means of two equations of state Peng-Robinson of three parameters and clustered into 13 pseudocomponents (for NIA and ENE-NOI reservoirs); despite sampling was not strictly representative, a calibration process was successfully done with experimental observations of PVT tests to account for gas, condensate, as well as, condensable gases production. And, DST results were matched to a VLP wellmodel.

A holistic analysis was carried out by integrating compositional simulation to sensitize production performance, and montecarlo simulation to evaluate for field size uncertainty when estimating gas and liquid resources. As a result, a matrix was designed to visualize and evaluate the most feasible development alternatives: depletion, depletion supported by a medium-size aquifer, partial and full cycling. 3D-Seismic and further appraisal wells will be useful towards reducing uncertainty of simulation model output and improving development decision-making process.
Innovative Methodology to Revitalize a Heavy-Oil Mature Field by Identifying Opportunities to Apply New Cycles of Steam Injection
Authors: Uribe J. P. , Pinilla J. F. , Cabrera D.
Published: December 2010

Tia Juana is a giant heavy oil field located along the Eastern shore of the Maracaibo Basin in Venezuela. This mature field has been producing oil of 12.6 API° from eight unconsolidated reservoirs from Miocene sandstone formations at 1200ft depth since 1928. The OOIP is 11.48MMMBBls with 3.18MMBBls of official recoverable reserves and cumulative production of 1.93MMBBls. This mature field has a long and rich history on which different recovery technologies have been proved such as: Cycle Steam Injection, Steam Drive, In Situ Combustion and SAGD: However, Cycle Steam Injection is by far, the most cost- efficient method to produce such heavy oil reservoirs.

High operating expenses affected by relative low production rates are usually exhibited by mature fields, heavy oil projects are additionally affected by the decreased price associated to oil quality. Under these conditions, an innovative methodology for economic value-adding opportunities to fields such as Tia Juana, is imperative in order to assure economic equilibrium for the project.

This paper presents an innovative methodology to boost the productivity scenario of mature heavy oil projects by the identification of opportunities to recover reserves, development of additional steam cycles in existing and new wells. The presented methodology is capable of quickly identifying wells with potential to be steam stimulated, quantity of possible cycles possible and predicted cumulative oil per cycle. This analysis was performed based on 2700 wells on which more than 9000 cycles and 43MM Tons of steam were injected.

The methodology includes six basics steps: production history review, conventional decline analysis, volumetric reserves estimation, determination of the well drainage radius and wells interference analysis, EUR calculations and the establishment of a correlation to predict the well behavior related to the Cycle Steam Injection. All these steps were integrated by an automated tool designed to manage the huge quantity of information in short time, honoring the cost and the efficiency issues. The application of this methodology allowed identifying the recovery of 108MMBBls by performing 2409 Steam Cycles in 563 existing wells (Fig. 7), and 113MMBBls by executing 3116 cycles on 576 new wells and finally allowed to adequately rank the opportunities based on the potential of reserves identified.
A New Approach to Hydraulic Fracturing With Relative Permeability Modifiers
Authors: Armirola F. , Machacon M. , Romero R. , Perez G. , Lastre M. , Ortega A. , Milne A.
Published: December 2010

In Colombia, relative permeability modifiers (RPMs) are often included in fracturing fluids to limit water production in wet producers. However, the results of their application are mixed. Since many reservoirs have an oil/water contact, or are close to an oil/water contact with poorly defined barriers, the fracture propagates into the water with minimal leakoff of the RPM into the fracture faces. In theory, the RPM polymer present in the interstitial water of the fracturing fluid leaks off into the fracture faces, as the hydraulic fracture propagates. For this to occur requires an inefficient fluid with high fluid loss. However, the properties of RPM fracturing fluids are similar to those of conventional fracturing fluids, highly viscous with leakoff control to ensure adequate fracture geometry and proppant placement. These properties favour vertical height growth of the hydraulic fracture and limit RPM leakoff into the fracture faces.

These limitations led to the development of a new fluid and placement techniques, with the objective of increasing the success rate of hydraulic fracturing in wet producers. A linear fluid comprised of polyacrylamide and polysaccharide polymers with a viscosity enhancer. The viscosity of which can be adjusted between 100 and 200 cp at 100 sec-1 over a wide range of temperatures. The relatively low viscosity of the fluid aids in limiting the net pressure and the risk of fracture height growth, in formations with low stress profiles. The addition of fibers provides a mechanical means to suspend and transport proppant, when deemed necessary. Hence, high fluid viscosity is no longer required for efficient proppant transport. By adjusting the ratio and concentration of the polymers, it is possible to independently adjust the viscosity and leakoff control of the fluid as a function of the formation permeability and stress profile. Doing so ensures that the desired fracture geometry is achieved while ensuring adequate leakoff to treat the fracture faces.

A fracturing campaign using this newly developed fluid in a mature field in Colombia resulted in an incremental oil production of 12%, while decreasing the water cut by 13%. This demonstrated that reservoirs that were not previously considered candidates for hydraulic fracturing can now be treated without increasing the water/oil ratio (WOR).

The use of this fluid, along with a new treatment design methodology, makes it possible to hydraulically fracture reservoirs with, or close to, an oil/water contact. This effectively extends the life of mature fields that are approaching their economic limits.
Surge and Swab Pressure Predictions for Yield-Power-Law Drilling Fluids
Authors: Crespo Freddy , Ahmed Ramadan , Saasen Arild
Published: December 2010

Surge and swab pressures have been known to cause formation fracture, lost circulation and well control problems. Accurate prediction of these pressures is of crucial importance in terms of estimating the maximum tripping speeds to keep the wellbore pressure within specified limits of the pore and fracture pressures. It also plays a major role in running casings, particularly with narrow annular clearances. Existing surge/swab models are based on Bingham Plastic (BP) and Power law (PL) fluid rheology models. However, in most cases, these models cannot adequately describe the flow behavior of drilling fluids.

This paper presents a new analytical solution, which is casted into a simplified model (dimensionless correlation) to predict pressure surge in a more convenient way. The steady state laminar flow equation is solved for narrow slot geometry to approximate the flow in concentric annulus with inner pipe axial movement considering yield-power-law (YPL) fluid. The YPL rheology model is usually preferred because it provides a better description of the flow behavior of most of drilling fluids. The analytical solution yields accurate predictions, though not in convenient forms. Thus, a numerical scheme has been developed to obtain the solutions. After conducting an extensive parametric study, dimensional analysis techniques were applied primarily to develop a simplified model that does not require a cumbersome numerical procedure. The new model is expressed in terms of dimensionless parameters.

The performance of the new model has been rigorously tested. Comparisons of the model predictions with previously published results have shown a satisfactory agreement. In most cases, the model makes better predictions in terms of closeness to relevant field measurements. That is due to the application of a more realistic rheology model. The presented model is very useful for slim hole, deepwater and extended reach drilling applications.
Drilling Process Creates Data Issues Requiring Innovative Data-Gathering and Interpretation Techniques
Authors: Pope Robert W. , Smith Charles H. , Mirzadeh Tahereh , Ramakrishna Sandeep
Published: December 2010

Directional-drilling processes that involve downhole motors, diamond bits, and bent subs have substantially changed the dynamics and economics of drilling to smaller, and more specific, geologic targets. This process produces some drilling-induced artifacts that include grooves and bit chatter in the wellbore wall. These created environments radically affect the measurements of density/neutron logs. In some cases, the alteration is so great that it affects resistivity logs, which makes the needed log properties impossible to determine with any accuracy.

The porosity measured by the density log appears to cycle high and low as the density pad loses and regains contact with the formation. The neutron porosity is also affected in many cases, exhibiting an identical cyclical character. The porosity measured by either traditional log cannot deliver a correct porosity, which leads to a cross-plot porosity estimate that is not accurate or useful. Another method must be used that does not depend on a smooth wellbore wall.

Dipmeter analysis is also affected because drilling-induced artifacts can be misinterpreted as geologic events. In many cases, the drilling process creates grooves that spiral down the wellbore. These grooves provide very distinct electrical contrasts, and the analyst may interpret them as actual geologic features. The use of an oil-based mud system provides an additional complicating factor that contributes to challenging dipmeter interpretations. Oil-based dipmeter interpretation was not consistent with expected results.

The solution to these difficult interpretation challenges requires the use of a different set of logs that provide answers independent of borehole quality. In this paper, we show how centralized, mandrel-deployed nuclear magnetic resonance (NMR) logs, unaffected by borehole irregularities, were used to define effective porosity. We also show how oil-based imagers were used to differentiate between drilling-induced grooves and beds or formation boundaries.
Gas Diffusivity Measurement in Reservoir Fluid at Elevated Pressures Systems for Transient Shut-in Modeling
Authors: Zainal Suzalina , Yee Hon Vai , Saaid Ismail M.
Published: December 2010

Gas-liquid diffusivity is investigated for many different oil recovery applications. Most interest is in the gas-oil diffusivity for enhanced oil recovery applications such as miscible gas flooding, immiscible carbon dioxide WAG (Water-Alternating-Gas) flooding and non-thermal heavy oil recovery by solvent injection. Other study includes the analysis of gas-water diffusivity to understand the methane hydrates formation. In designing an enhanced oil recovery process, for instance, further information on the rates and amount of mass transfer by diffusion is required. The focus is to have better insight of the mass transfer mechanisms, particularly at the reservoir level.

A more downstream application of gas-liquid diffusivity measurement is its application in transient modeling. The interest is at the production tubing, primarily in describing the phase redistribution process in a shut-in well. Gas-liquid diffusivity has been suggested to account for the molecular interactions and distribution between the gas and oil phase in a producing well during transient flow. Mass transfer being the transport phenomena, causes the molecules in the fluids to rearrange to attain an equilibrium system. This process of rearrangement is transient and driven primarily by the concentration gradient in the gas and oil system. The diffusion coefficient parameter which is a function of mass transfer introduces a time factor to the overall phase segregation process. Higher diffusion rate is anticipated to contribute to faster phase redistribution and contrary if vice versa. In transient modeling for shut-in condition, this information is useful to enable accurate simulation of fluid redistribution period prior reaching equilibrium.

This paper presents the gas-liquid diffusivity measurement and analysis involving Malay Basin's hydrocarbon fluid samples and its applications to the transient shut-in modeling. It also highlights on the reliability of a published method designed for a heavy oil system when applied to Malaysian light to medium crude oil systems.
Practical Modelling of Asphaltene Related Damage in Volatile Oil Reservoirs
Authors: Restrepo A. , Ruiz M. , Rendón N. , Lopera S.
Published: December 2010

Asphaltene deposition related damage is a well known phenomenon during production of highly under saturated volatile oil systems. It's modelling and control has been broadly documented although this last practice has been restricted to the near wellbore region where its impact seems to be maximum and where treatments can be effectively deployed.

The following paper presents a modelling approach for the estimation of the asphaltene deposition profile in highly under saturated volatile oil systems. This profile would allow predicting effective permeability loss as a function of pressure provided a set of asphaltene content measurements taken at wellhead through time. A simple asphaltene solubility model coupled with laboratory measurements are combined to propose a precipitation-deposition model that estimates expected k losses when thermo dynamical changes such as methane injection or pressure depletion are present. The output from the model which is a k function of pressure was incorporated into a single well model to match well's actual response after near wellbore dissolution treatments and after injection gas appearance in the drainage area. Laboratory tests consisted of core flooding experiments that allowed obtaining basic relationships between mass of asphaltene deposited and damaged Ko.

The present model was developed as a tool for benefit estimation if an asphaltene dissolution technique is applied at reservoir scale. The present approach is proposed as a simple and practical way of estimating asphaltene related damage in compositional volatile oil reservoirs.
Improvements in Routine Core Analysis on Whole Core
Authors: Perez C E. R. , Zapata A J. F. , Gonzalez M. , Herrera M. N.
Published: December 2010

A naturally fractured reservoir is composed by a system of fractures created by breakdown of the layers, caused by tectonic movements. Although all reservoirs have some fractured grade, only are considered naturally fractured, those where the system of fractures presents any effect upon flow of fluids.

Whole core analysis is critical for characterizing directional permeability in heterogeneous, fractured reservoirs. Whole core measurements are essential for heterogeneous reservoirs because small- scale heterogeneity may not be appropriately represented in plug measurements. For characterization of multiphase flow properties in heterogeneous rock, routine and special core analysis in whole core is also required.

In this paper, we provide an overview of routine and special core-analysis measurements on whole cores. Improved experimental equipments for measurement of routine core analysis on whole core (fluid saturation, clean, directional permeability, and porosity) under a maximum confining stress of 10,000 psi, were made in the ECOPETROL-ICP's routine and special core laboratories. The advantage of these equipments is that allows evaluating directional permeability (x, and, z) considering variations in permeability caused by fractures and other heterogeneities. Finally we discussed results from routine core analysis on whole cores for Colombian heterogeneous sandstone. Also in this paper the effect of scale (sample size) on the measured properties are also shown.
Planning and Interpretation of Offshore-Field Tracer Tests Using Accurate and Refined Tracer Simulations
Authors: Huseby Olaf , Sagen Jan , Wangen Magnus , Viig Sissel Opsahl
Published: December 2010

Tracers are chemical compounds or radioactive isotopes used to label injection water and gas in petroleum reservoirs. In inter-well tracer tests (IWTTs), well connections and fluid patterns can be established when the tracer appears in production wells. Tracer simulation is an invaluable tool to ease the planning or interpreting results of IWTT. In this paper we introduce a novel tracer simulation methodology which is based on a decoupling from the underlying reservoir simulation. The method- ology ensures accurate and very fast tracer simulation; with CPU times in the order of a few percent of ordinary reservoir simulation. The method is based on solving the tracer equations on a grid separated from the underlying reservoir simula- tion. The separate tracer grid can be refined, with significant improvements in the accuracy of the tracer solution, without affecting the speed of the reservoir simulation. Accurate refinement as well as localized tracer grid refinement is introduced and investigated. Local refinement is compared to global refinement, and we demonstrate that local refinement can be a valid strategy in many cases. We demonstrate the methodology on a real reservoir case, and show that predicted breakthrough times are significantly affected by the accuracy of the solution. The method improves accuracy by overcoming numerical diffusion through separate tracer-grid refinement. In our specific real case, the breakthrough time was underestimated by about one year in the solution obtained using standard methods. This was corrected using the new methodology. The large difference in simulated breakthrough time between the improved and corrected solution has important consequences for the planning and interpretation of IWTT.