bluuebunny/crossref_metadata_2025_split huggingface dataset:
Achieving Low Interfacial Tension with Industrial Available Surfactants
Authors: Guy Biesmans , Salazar Luis , Miller Angie 
Published: April 2012

Abstract
Growing interest in Enhanced Oil Recovery (EOR) has generated renewed interest in surfactants for Chemical EOR (CEOR). While new developments typically build on past experiences of surfactant injections, academic and research institutes continue to propose new high-performance surfactant structures. Although these new molecules can easily be provided in sufficient quantities for laboratory tests and limited field trials, scale up to large commercial application could prove challenging. Moving to production on a large commercial scale will require the availability of raw materials and suitable production assets. In addition, regulatory compliance issues must be addressed, as must future supply chain efficiency.
This paper describes the development process for surfactants capable of attaining low interfacial tensions. It specifically addresses the impact of raw material availability and quality, production assets and regulatory compliance on a global basis.
Surfactant performance envelope data is presented as the first step to enable selection of potential candidate structures for given field conditions. The influence of the selected production assets for scale up to commercial quantities on the molecular composition of the final product is also illustrated. As will be seen, changes in the raw material feed and feed processes determine the poly dispersion of the resulting product. The impact of variations in chemical structure and total product composition manifest themselves in the product performance envelope. We show how small changes in composition not only impact performance, but also affect regulatory compliance and the corresponding supply chain processes.
A holistic approach to surfactant development, which considers the full process from product concept to commercial large-scale production, is essential to make CEOR successful. The development process must consider the sustainability of the proposed structures and processes required to make them. Here we will demonstrate why design for future growth in demand must be built in from day one of the product concept.
A Holistic Risk Analysis Approach for Reservoir Modeling
Authors: Huerta V. A. , Lanchimba A. 
Published: April 2012

Abstract
During recent years, some wildcat wells located in remotes areas of the Peruvian Amazonian rainforest tested commercial volumes of oil and gas. Beyond this preliminary success, reservoir uncertainties due to seismic interpretations, and limited cores and log data impose complexity in reservoir characterization; major sources of uncertainties can be broadly group into three main categories: structural, rock & fluid properties and reservoir performance.
Applications of numerical simulation have been extended to conceptualize reservoir characterization in early development phases; coupled with statistical experimental design, montecarlo simulation and scenario analysis, numerical simulation become the most powerful tool to fulfill a complete sensitivity analysis with significantly fewer simulation runs towards sizing downhole and surface facilities, as well as, optimizing field development.
The proposed holistic approach was applied to a new lean gas condensate field in the Peruvian rainforest so as to sensitize production plateau, evaluate rock & fluid properties, field size and recovery factors, predict liquid yield performance, analyze water influx and optimize field development. Pareto plots and response model surfaces showed that porosity, permeability, position of gas water contacts and faults transmissibility are the main factors affecting field size, as well as, gas and liquid recovery. In addition, cumulative plots showed distribution of gas & condensate recoverable resources. Finally, a matrix of scenarios showed that blowdown strategy is the best development alternative for this lean gas condensate field.
Effect of Pressure and Air Flow Rate on In-Situ Combustion Experiments of Heavy Oil
Authors: Cazarez-Candia O. , Cruz-Hernández J. 
Published: April 2012

Abstract
In this work in-situ combustion experiments were carried out using a combustion tube of 1 m. in length and 0.0381 m. internal diameter. Experimental tests were performed with heavy oil (18.1 API and 0.6614 Pa-s) from a Mexican field. The aim of this study was to survey the effect of pressure and air flow rate on temperature, oil recovery, front velocity, oxygen utilization and produced gases.
The experimental conditions were: 1) oil and gas saturations, 38% and 28% respectively, 2) porosity, 41%, 3) initial temperature, 373 K., 5) air flow rate, 5.83×10−5 m3/s and 7.5x×0−5 m3/s, and 6) pressure, 2068.4, 3447.4, 4826.3, 6894.7 and 10342.2 kPa. The results indicate that the in-situ combustion method is technically applicable to the rock-fluid system tested. Average combustion front temperatures were recorded in the range of 713 to 815 K, and the oil recovery factors were greater than 84%. The combustion front velocities were from 4.64 to 8.05 m/s.
It was found that, as the pressure increases (5.83×10−5 m3/s): 1) the average combustion front temperature and the combustion front velocity increase when pressure is smaller than 6894.7 kPa, 2) the oil recovery, and 3) the oxygen utilization diminishes. However the average combustion front temperature and the combustion front velocity decrease when pressure is larger than 6894.7 kPa. On the other hand, all such parameters increase as the air flow rate increases from 5.83×10−5 to 7.5×10−5 m3/s.
The basic combustion parameters (fuel consumption, air requirement, air/fuel ratio, atomic H/C ratio, oxygen utilization) obtained from the experiments may be used to design a pilot project planned for the field.
3D Analytical Modeling of Hydraulic Fracturing Stimulated Reservoir Volume
Authors: Yu Guang , Aguilera Roberto 
Published: April 2012

Abstract
An easy to use analytical 3D model is developed to simulate the growth of stimulated reservoir volume (SRV) with time once a hydraulic fracturing job is started in an anisotropic poroelastic medium. In the proposed method, diffusivity coefficients in three dimensions are determined first by calibrating the model with an actual 3D microseismic-event cloud. Then the geometry of SRV is predicted under different stimulation conditions. The method permits studying the geometry of hydraulic-fracturing SRVs in both vertical and horizontal wells. The analytical model is corroborated with the use of a numerical simulator.
The proposed method is important because in unconventional low-permeability reservoirs, such as shale and tight gas reservoirs, productivity depends primarily on permeability of the SRV and the reservoir area contacted by the SRV. Microseismic monitoring has been shown to be a useful technology to study the characteristics of hydraulic fractures. As such, the optimum is to constrain the analytical 3D model developed in this study with the use of microseismic data. It is concluded that this easy to use, yet accurate analytical model, is a viable tool for analyzing the orientation and geometry of hydraulic-fracturing SRV and for predicting other SRVs in the same reservoir. Examples of applications which can be reproduced easily in a spread sheet are presented in detail.
The Effect of Aquifer Condition on Methane Recovery for CO2 Injection in Coalbed
Authors: Kim K. H. , Lee M. K. , Sung W. M. 
Published: April 2012

Abstract
The purpose of this paper is to investigate the influence of various aquifer conditions on the CO2 displacement efficiency and methane recovery in the coal seam. The movement of CO2 in cleat is sensitively dependent upon aquifer condition as well as sorption characteristics of coal, since the pressure of coalseam is determined based on the position of aquifer. In this study, methane recovery for CO2 injection process was analyzed regarding the contacting position and strength of the aquifer. We ascertained that both methane recovery and CO2 sequestration are inefficient when the hydraulic connection between overlying aquifer and coal seam is strong. This is because buoyancy effect causes gas leakage to the overlying aquifer although CO2 displacing methane has a greater affinity compring to methane. Although the vertical permeability of underlying aquifer is great, the effect of methane recovery and CO2 sequestration are efficiently successful during CO2-ECBM process because the leakage of both the amount of injected CO2 and desorbed methane is negligible. Although the injected CO2 is effetively sequestrated in the edge aquifer case, ECBM recovery shows irregular efficiency in part due to the asymmetrical flow of the injected CO2. It is considered that the design of proper strategies regarding CO2 movement means a lot to the aspect of methane recovery and CO2 sequestration to maximize economic profit.
Initial Characterization of an Extra Heavy Oil Carbonate Exploratory Field
Authors: Aguilar E. G. , Gonzalez L. M. , Ruiz V. G. 
Published: April 2012

Abstract
Reservoir discoveries are getting more difficult and complex. Currently in the Gulf of Mexico new Oil Fileds are being characterized. The presence of secondary porosity into dissolution cavities with extra heavy oil become in a complex challenge to characterize those exploratory reservoirs. Only 18 wells have been drilled in a total area of 1100 km2, with water depth between 100 and 680 meters. The API gravity varies between 6 and 13 °API, which represent an adverse water-oil mobility ratio with a water-oil contact into fractures with high permeabilities. The main objective of this job is to show an advanced technique of Geosciences and Reservoir applied to an Extra Heavy Oil Carbonate Exploratory Field, to estimate the Original Oil in Place (OOIP) with probabilistic methods and define associated reserves to the field development.
The methodology applied starts with geophysics interpretation; Geo-statistics methods in the velocity model were used for depth conversion and a geo- mechanical model also was built for the development well design. The 3D Model includes: wells data, as well test, cores, electrical logs, horizons and faults in time and depth, geological tops, petrophysics, contacts and velocity model. Due to the high uncertainty, the 3D model integration was a challenge. The final result was a base case with a lithology and petrophysics properties distribution such as porosity, water saturation and net pay, used to calculate the OOIP.
Different workflows were used for the final result. Velocity variations were analyzed for the impact of each associated variable to the OOIP and understand area and thickness variability. Bayers Theorem was used for porosity, water saturation and net pay. Analogous wells by lithology were built, making more consistent the results and represent the reservoir in a best way possible into a numerical simulation model. Static and dynamic elements were integrated for reservoir and fluid behavior, including sensitivity analysis. The final result has uncertainty analysis, building of proxies and makes probabilistic forecasts to establish mitigation plans and define the more optimistic field development.
Geomechanics Applied to Perforating Design: One Solution to Reduce the Sand Production Risk
Authors: Quintero Y. , Jaimes M. , Martin D. , Rivera G. 
Published: April 2012

Abstract
One of the main causes of sand production is the rock faulting, situation that is given by the stress condition, pressure and mechanical properties that is applied. We use geomechanical criteria for the design of gunfire (density, diameter, penetration, phase and drop pressure for cleaning, etc.). It is possible to generate stable conditions that reduce the risk of the rock failure.
Therefore, identified some geomechanical criteria to determine areas of highest stress contrasts, which can accelerate the rock failure, areas with increases in stresses for proximity effect between canyons, among others, must be taken into account in the perforating operations in areas susceptible to sand production, in order to reduce the risk of the rock failure and start early sand production. With the aid of geomechanical models and these criteria it is possible elaborate a methodology for optimal perforating design.
Milestone in Production Using Proactive Azimuthal Deep-Resistivity Sensor Combined with Advanced Geosteering Techniques: Tarapoa Block, Ecuador
Authors: Guevara A. , Sandoval J. , Guerrero M. , Manrique C. A. 
Published: April 2012

Abstract
A recent challenge of drilling a horizontal well in a Ml Sandstone reservoir presented high seismic uncertainty and limited lateral extent; this well is located in the Napo formation of the Oriente basin in Ecuador. The geology in this basin is complicated; most of the reservoirs are formed from a small, stacked-channel sandstone sequence. As a result, well-to-well reservoirs are difficult to correlate because of their limited lateral extent. Horizontal wells placed in this kind of environment generally require adjustments in the planned directional well trajectory and modification of the navigation TVD when required.
The primary goal of this project was to maintain the well in the sweet spot of the reservoir to improve productivity. As a final delivery, the structural map of the top of the M1 Sandstone enabled the customer to adjust the seismic information in the zone of influence of the well. A major drilling company assumed the challenge by using a rotary steerable system, proactive logging-while-drilling azimuthal resistivity sensors, and 3D geosteering techniques to place the well in the sweet spot of the reservoir and to ensure the permanence in the sandstone reservoir.
The azimuthal deep resistivity sensor can provide a broad quantity of curves with various depths of investigation (DOIs). Having this information as an entry, the geoscientists applied the three logical geosteering phases of model, measure, and optimize. At the modeling stage, the geosteering team selects the appropriate proactive set of variables to transmit in real time, including compensated resistivities at various ranges of investigation, images, and geosignals according to the geology in the area, reservoir thickness, and existing resistivity contrast. The measuring stage begins by obtaining the selected variables in real time with average resistivities that enable the calculations of the distance-to-bed boundary (DTB) using a forward-modeling technique, while real-time images are compared against modeled information for stratigraphycal positioning. During landing, the drilling and geology departments agreed that the reservoir top was 35 ft (10.7 m) shallower than expected. At this point, the directional drilling plan needed to be changed, beginning the optimization stage even before the horizontal section began.
The appropriate combination of reactive and proactive logging-while-drilling sensors enabled the well to be placed parallel to the top of the reservoir, maintaining an optimal distance of 1 to 3 ft, with 100% reservoir exposure in the pay zone and no exits.
The main objectives of geosteering were achieved. The well produced 6,800 BOPD after an initial estimate of 800 BOPD. The top of the reservoir was mapped, thereby improving knowledge of this zone for future study.
Pore Scale Modeling of Gravity Drainage Dominated Flow under Isothermal and Non-Isothermal Conditions
Authors: Argüelles F. J. , Babadagli T. 
Published: April 2012

Abstract
Immiscible or miscible gas injection and steam assisted gravity drainage are well known examples of gravity dominated recovery processes under isothermal and non-isothermal conditions, respectively. It is commonly observed in these processes that field scale applications yield less recovery than estimated. In order to clarify the reasons associated with the amount of the remaining oil in these processes, especially for the non-isothermal ones such as steam assisted gravity drainage (SAGD), pore scale experimental analysis of the mechanics is needed. In this paper, as complementary to our previous work (Argüelles and Babadagli, 2011) that used horizontally positioned circular capillaries, we studied the gravity drainage dominated flow of heavy-oil at pore scale using vertically positioned square and circular capillary tubes. Heavy crude oil samples were used and an elementary volume in the swept zone of SAGD was simulated using a single capillary tube. Detailed experiments were carried out to analyze: (1) the effects of oil viscosity on non-isothermal gravity drainage (including free fall), (2) behavior of co-current gravity driven displacement, (3) interplay among capillary, gravity and viscous (injection rates) forces and wettability, and (4) residual oil saturation and phase distribution in the capillaries. Also, we compared the residual oil saturation development results obtained for square capillaries with those for the circular ones having a diameter approximately equal to the side of the square capillary tube.
Novel Barium Sulfate Scale Inhibitor for Use in High Iron Environments
Authors: Dickinson W. , Sanders L. 
Published: April 2012

Abstract
Iron is known to affect the performance of polymeric and phosphonic acid based inhibitors used to control barium sulfate scale during oil and gas production. To evaluate these effects, the performances of both types of inhibitors have been determined in the presence of iron in simulated oilfield brine. Iron adversely affected the performance of the polymer but enhanced the performance of the phosphonate inhibitor. Evaluation of blends of the two inhibitors showed improved performance compared to either type of inhibitor used separately. An optimum ratio of polymer to phosphonate was determined which achieved greater than 90% inhibition of barium sulfate formation over the range 0 – 120 ppm iron.
The Way Forward for Deepwater and Ultra Deepwater Drilling in Trinidad and Tobago
Authors: Rajnauth J 
Published: April 2012

Abstract
Future deepwater drilling in Trinidad and Tobago will definitely present enormous challenges. During the period 1999 to 2003, eight deepwater wells were drilled in deepwater acreage. None of these wells found hydrocarbon in economic quantities although abundant reserves have been found in the shelf area (&lt; 1000 meters water depth).
The data from these wells would be useful for further deepwater and ultra deepwater drilling in Trinidad. To date, no wells have been drilled in our ultra deepwater acreage but seismic acquisition and processing has been undertaken. Thus lessons learned from the first deepwater campaign will definitely propel the way forward for further exploration works in deeper waters. We have to adapt our operations to accommodate the problems associated with our first phase of deepwater drilling in our area. This paper will look at the approaches we should adapt in the next phase of deepwater drilling. Some of these issues include rig selection, well location, well design and planning, environmental studies (wind, wave, climate etc.) and shallow hazard assessment. The key learnings from previous deepwater drilling events are useful in future operation in Trinidad and Tobago.
Borehole Geometry Estimation through Real Time Measurement of Cavings Flow while Drilling
Authors: Carvajal J. M. , Salcedo A. Lache , Mateus D. C. , Caceres E. 
Published: April 2012

Abstract
Measuring cuttings and cavings flow while drilling allows to account the amount of cuttings which are drive out from the annular section of the hole, quantify the volume of collapse in the wellbore and estimate the final well geometry at real time conditions, these information can be used to develop strategies that may help to control wellbore stability while drilling.
The design, construction and a field testing of a prototype that can automatically record data while drilling from cavings and cuttings flow to be analyzed in real time is presented in this paper, the prototype is used to identify situations in which cuttings and cavings flows are high enough to cause instability of the drilled well in real time. The system was developed to estimate the actual diameter of the well based on information gathered by it, this can be used to establish a comparison between the ideal diameter and the calculated which will allow identifying zones in which the wellbore failure may occur and figured the approximate size of collapse.
This prototype has been used in several wells in Colombia, located at different basins of the country, a study case of a well sited at Middle Magdalena River Valley Basin is presented in this article, the results obtained from the use of this tool are satisfactory and can accelerate the process of decision making and evaluation of the borehole stability while drilling since the responses are given in real time.
Stable Emulsion and Demulsification in Chemical EOR Flooding: Challenges and Best Practices
Authors: Nguyen Duy , Sadeghi Nicholas 
Published: April 2012

Abstract
In this paper, factors such as key issues (e.g. emulsions), challenges (e.g. water treatment), and best practices (e.g. combination of equipment design and demulsifier to treat emulsions) associated with chemical enhanced oil recovery (CEOR) are presented. During the application of chemical EOR floods, breakthrough of the injection chemicals such as surfactant and polymer or polymer alone periodically occurs resulting in stable emulsions. This paper was compiled from the literature to report the effects of alkali, polymers, surfactants, asphaltenes, resins, and shear rates on emulsion stability. When treated with polymer alone, the produced fluid was not very stable and resolved into two phases: oil and water. However, the water exhibited a high oily content and was difficult to treat due to the adsorption of polymer onto the surface of the oil droplets. Zeta potential measurements indicated that oil droplets were not only stabilized by steric stabilization of the polymer but also by electrostatic stabilization. The effect of polymer on emulsion stability in SP (surfactant and polymer) or ASP (alkali, surfactant, and polymer) floodings is complicated. Polymer can form a "bridge" between two oil droplets and decrease the emulsion stability; however, polymer can also enhance the emulsion stability via electrostatic and steric stabilization. Asphaltenes and resins present in the crude oil form a rigid film around water droplets, contributing to high BS&W values. Surfactants and alkali decrease the interfacial tension and zeta potential, contributing to the stability of oil droplets. As concentrations of the injection chemicals in the produced fluid varied, the stability of the emulsion also changed. As a result, the selected demulsifier has to be robust. In this paper, water soluble demulsifiers and oil soluble demulsifiers were used to treat the emulsion. The demulsifier greatly lowered water content in the oil phase (BS&W&lt;0.5%) and oil concentration in the water phase (less than 50 ppm). The demulsification mechanism was also investigated in terms of elastic modulus, particle size, and interfacial tension. Application of this novel demulsifier resulted in a much more effective oil/water separations process with the production of dry oil and clean water at a pilot ASP flood that was experiencing very stable emulsions.