bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Simulation on CO2 Leakage through Fractures along Wells Using Discrete Fracture Modeling
Authors: Huo Da , Gong Bin 
Published: February 2011

Abstract
The first and foremost task for carbon storage is to find proper locations to permanently store CO2 which are injected into deep saline aquifers. However, fractures in the reservoir as well as channels along the wells form preferential pathways for CO2 transport to make it easily escapes from the reservoir. Various scientific studies, pilot CCS programs and commercial CCS projects have shown that leakage problems will be detrimental to the environment and safety to human race.
Modeling CO2 flow in fractures along the well remains a challenge. In this work, several CO2 pathways are characterized, including fractures in cement, casing and the rock. Discrete Fracture Modeling (DFM), which represents fractures individually and explicitly, is applied to simulate CO2 movement in a saline aquifer. This requires unstructured gridding of the saline formation using Delaunay triangulation and transmissibility evaluation between each pair of adjacent cells. Simulations have been done using General Purpose Reservoir Simulator with a non-neighbor connection list.
Several examples including flows through wellbore failures, sloped layers as well as Hydraulic fractures are presented. Through the simulation results, it is found that near well fractures act as extremely preferential flow paths for CO2 transport. Fracturing would help CO2 retained in the target aquifer.
The main application of the framework presented in this paper is to help those involved in evaluation and planning of possible CO2 storage location selection to identify and quantify possible leakage risks through drilling and completion induced fractures.
The Effect of Rheological Properties of Alkali-Surfactant-Polymer System on Residual Oil Recovery Rate After Water Flooding
Authors: Ma Wen-guo , Xia Hui-fen , Yu Hong-yu 
Published: February 2011

Abstract
Through rheological experiments and indoor core experiments, the rheological properties and oil displacement efficiency of Alkali-Surfactant-Polymer (ASP) system containing amphoteric surfactants is studied at ultralow interface tension (0.001mN/m). The effects of changing the concentration of polymer (0.5, 1.0 and 2.0g/L), alkali types (Sodium carbonate and sodium hydroxide) and concentration of Sodium carbonate (0.3-1.5%) on the rheological properties and oil displacement recovery is studied. The viscosity of ASP system increases with mass concentration of polymer increased, and the viscosity of ASP system decreased with mass concentration of Sodium carbonate increased. The viscosity of the system containing 0.6% Sodium hydroxide is higher than the system containing the same concentration of Sodium carbonate. Indoor man-made core displacement experiment results showed: With the mass concentration of polymer changing from 0.5g/L, 1.0g/L and 2.0g/L, the improving value of recovery rate is 25.26%, 21.05% and 22.1% respectively. After water flooding, with the changing of mass concentration of Sodium carbonate on ASP from 0.3%, 0.6%, 1.0% and 1.5%, the recovery rate of ASP systems is 25.26%, 21.42%, 23.81% and 35.35% respectively, the increment of recovery rate is all more than 20.0%, the Total recovery rate is 85.26%, 79.75%, 83.33% and 93.93% respectively. This research results in this paper has important guiding significance on production design.
Integrated Formation Evaluation in an Anisotropic Reservoir Offshore Deep Water Indonesia Using a Combination of Image Logs, WFTs and Mini DSTs for Pay and Hydrocarbon Definition
Authors: Capone Graziano , Malossi Alfio , Mele Maurizio , Damronsak Chantipna , Valdisturlo Antonio , Beretta Enzo , Clementi Alice , Al Shamma Basil 
Published: February 2011

Abstract
Reservoir characterization of laminated turbiditic sequences is often problematic due to the highly anisotropic setting, which affects the formation evaluation from conventional LWD, wireline logs and mudlog data. The reservoir, fluid content and pay petrophysical parameters are usually underestimated. Time and cost constraints can prohibit the utilization of new generation high resolution tools and to perform conventional DSTs.
An oil and gas bearing well in deep water Indonesia was accurately evaluated with a relatively low time and cost investment in formation evaluation and data acquisition. Pay, porosity and water saturation were calculated by integrating high resolution image logs with standard wireline logs. An ample dataset of reliable formation pressures and fluid samples were obtained in a thin bed environment from Wireline Formation Testing (WFT) utilizing standard and large size probes.
Mini DSTs were carried out to characterize reservoir and fluid properties. Thin beds were recognized using an imaging log in oil base mud and through a Thin Layer Analysis (TLA) approach the net sand calculation was enhanced. The TLA result was cross-checked with an electrofacies profile obtained using standard well logs (density, neutron and gamma ray) and calibrated with the sedimentological core description from other wells. In the final net sand computation beds not corresponding with actual reservoir facies were not considered so that only the effective reservoir was included.
The result of this integrated approach resulted in an increase in the net pay evaluation in comparison with the conventional formation evaluation, and confirmed the high potential of nonconventional pay in a deep water environment. An exhaustive reservoir and fluid characterization was also achieved without coring and conventional DSTs.
Superheated Steam Huff and Puff to Revivify a Marginal Pre-salt Heavy Oil Reservoir
Authors: Xianghong Wu , Benjing Dong , Anzhu Xu , Zifei Fan , Ruifeng Wang 
Published: February 2011

Abstract
The Kenkiyak pre-salt oil field is a heavy oil reservoir with the average porosity of 36.6%, the average permeability around 1875x10−3μm2, the buried depth between 290∼380 m, the dead oil viscosity within 144∼691mPa.s @20°C, the reservoir temperatures between 18.8∼20°C. From 1967 to 2002, the reservoir was developed by depletion. As a result, the average reservoir pressure has dropped from 5.9Mpa to 1.8 MPa. The serious heterogeneous characteristics and rapid water invasion made the water-cut of wells as high as 76%. Furthermore, the average well production rate declined from the original 8 m3/d to the later 1∼2m3/d., and was staying at this level for a long time. The field was hovering at the economical margin in 2002. In 2003, the operator launched a series of studies and pilot tests to improve the production performance and economic benefits. But there is no proven current recovery technique that can be economically applicable to such viscous oil reservoirs. However, there are huge amount of hydrocarbon accumulation in such reservoirs that can only be exploited with new concepts. Superheated steam huff and puff as a superior technology for the recovery of high water-cut heavy oil reservoirs has been pilot tested in Pre-salt oil reservoir and has found satisfactory development results. This work introduces this new recovery technique of superheated steam huff and puff to effectively develop serious water-invaded heavy-oil reservoirs, and reviews the main practices we have performed, including simulation studies, pilot tests, challenges encountered and solutions, and current effects. Valuable knowledge and experiences have been obtained in terms of superheated steam huff and puff in such reservoirs after many years depletion development, providing reliable operational experience and technical support for Kenkiyak pre-salt reservoir and similar oilfields.
The Italian Contribution to the European Initiative for the Capture, Transport, and Storage of CO2
Authors: Cau G. , Girardi G. , Macini P. , Mesini E. , Persoglia S. 
Published: February 2011

Abstract
The need to update energy policies worldwide in order to deal with climate change effectively is unanimously considered a priority by the scientific and political communities as well as by the general public. It is also unanimously believed that what is needed is an approach integrating energy usage and production. Such an approach requires that Countries speed up the transition towards an economy not any longer based on fossil fuels, but instead on increased demand/supply efficiency and on renewable sources, while aiming at clean technologies and reducing emissions wherever fossil fuels are used. Italian universities and research centres have started specific studies and programmes regarding CO2 Carbon Capture and Storage (CCS). Such initiatives have been financed thanks to European and National funding. The latter has financed a vast programme based on a strong synergy between national stakeholders, also via the participation to international initiatives like the Carbon Sequestration Leadership Forum (CSLF) and the European Technological Platform for Zero Emission Fossil Fuel Power Plants (ZEP). The main strength of the Italian system lies in the strong will of the Italian Government to adopt a new energy policy. The second strength is the starring of the main Italian industrial subjects, above all ENEL and ENI, which have started important demonstrative projects (not to mention Techint, Carbosulcis, and others). Another important issue is the large quantity of geophysical data available for many parts of the Italian territory that are strategic for assessing the CO2 storage capacity. Finally, Italy is of great interest for the scientific community because of the presence (onshore and offshore) of numerous natural sites of CO2 leaks, thus offering unique opportunities of evaluating its impacts on the natural environment, and of tuning up the monitoring techniques of CO2 leaks.
Case History: First of its Kind: Installation of the Multizone Single Trip MST Technology in Deep Water, India
Authors: Joseph Kevin Peter 
Published: February 2011

Abstract
The paper summarizes the two installations of Multi-Zone Single Trip (MST) technology in deepwater Bay of Bengal, India. The unique challenges of deepwater operations, the technical hurdles, high-stakes economics and the untapped potential rewards have further stimulated the innovativeness of the oil industry stakeholders. In this case, a major private operator in India, a country with growing national energy demands, chose to introduce Multi-Zone Single Trip completion technology in the development of its deepwater gas fields. Historically where sand control is required, cased-hole frac packs have been the preferred completion method, due to its greater completion reliability, relative operational simplicity, higher production rates and greater functionality for multiple zones. However, conventional stacked cased-hole frac-packs require multiple trips, making it both time-intensive and extremely costly in deepwater operations. Multi-Zone Single Trip technology has proven its potential to significantly improve economics by drastically reducing completion time and cost. Despite the significant challenges encountered in these first installations, both wells were successfully delivered with all ten zones treated, five zones per well, with complete sand control and zonal isolation. The paper discusses the challenges encountered, the success factors and recommendations for future projects.
Experimental Investigation on the Viscous Effect on Two-Phase Flow Patterns and Hydraulic Performance of Electrical Submersible Pumps
Authors: Trevisan F. E. , Prado M. G. 
Published: February 2011

Abstract
Using a visualization prototype built from original Electrical Submersible Pumps (ESP) components and with minimal geometrical modifications, a pioneer experimental procedure was developed and conducted to address the viscous effect on liquid-gas two-phase flow through these types of pumps.
Based on dimensionless groups that govern centrifugal pump single-phase performance, two-phase experiments were conducted at different shaft speeds (15, 25, 30 Hz), non-slip void fractions (up to 5%) and viscosity values (46 to 161 cP), while liquid rates were kept constant at 60% of the maximum rate at the defined shaft speed. High speed video footage was taken from the entire impeller flow channel and stage incremental pressure was measured.
The authors identified four liquid-air flow patterns inside the impeller channels: Agglomerated Bubbles, Gas Pocket, Segregated Gas and Intermittent Gas. By comparing the images with the differential pressure data, it was concluded that the Agglomerated Bubble pattern is responsible for the initial head degradation and that the surging event coincides with the Gas Pocket structure, indicating that this is an interface instability problem. Another conclusion made was that the increase in viscosity caused surging to occur at lower void fractions which could be compensated by increasing rotational speed.
The significance of this work is given by the fact that several authors have investigated centrifugal pump performance under two-phase flow; however, previous experiments have been conducted only with water as the liquid, thus neglecting the viscous effect on the two-phase flow mixture. In most of the petroleum industry's applications ESPs operate with oil and natural gas. Thus presenting a knowledge gap between scientific research and field applications, this starts to be addressed in this work.
Evidence of Strong Fracture Height Containment Based on Complex Shear Failure and Formation Anisotropy
Authors: Barree R. D. , Conway M. W. , Gilbert J. V. , Woodroof R. A. 
Published: February 2011

Abstract
For years, uncontrolled fracture heights have been modeled for layered reservoirs using Mode-I tensile failure driven threedimensional (3D) and pseudo-three-dimensional (P3D) fracture geometry models. In these models stress contrast between layers has been assumed to provide the dominant height containment mechanism. Meanwhile, many of the completion diagnostic tools were revealing more contained fracture heights and were thus being discounted. As more diagnostic tools have been employed, it has become apparent that the frac models may have been incorrectly over-predicting fracture heights in many cases. Mine-backs and post-frac coring revealed more contained fracture heights, as did radioactive tracer logs, treating pressure profiles, fall-off data, production modeling, and the absence of perforated interval communication.
This paper will present some of the diagnostic data that support more contained fracture height development. These will include case histories from tight gas sands and shales in which restricted fracture height observations are supported by diagnostic observations. It will also go one-step further, by proposing mechanisms which contribute to fracture height containment. These include poroelasticity, abnormally high "trapped" pore pressure, and complex shear in layered or anisotropic media. It will present some modeling methodologies that place more emphasis on poroelasticity and Mode-II shear failure than current conventional fracture models. The need for investigation, and adoption, of these methodologies will be corroborated by diagnostic data.
Designing and Testing Cement System for SAGD Application
Authors: Patil Rahul , Garnier Andre , Galdiolo Gregory , Patil Sandip , Ravi Kris , Ferreira Luis 
Published: February 2011

Abstract
In recent years, the focus of the oil and gas industry has shifted toward the production of oil from deep and harsh environments. This has been possible because of advanced technologies coming available to the industry. However, challenges still remain in designing materials to withstand certain harsh environment. To satisfy the ever-increasing demand for oil and gas, the industry is tapping heavy oil, which poses unique challenges.
Steam-assisted gravity drainage (SAGD) technique has made it possible to reduce the viscosity of heavy oil and render it mobile. In this technique, steam is injected through an injector well and down to the reservoir where temperature can be raised to 260°C (500°F). This reduces the viscosity of heavy oil but imposes severe thermal stresses on the cement sheath and casing.
Such stresses could hamper zonal isolation and result in the release of steam to the surface. Designing a cement slurry for such applications is challenging of various aspects, such as mixability, pumpability, placement in the annulus, sheath resiliency, permeability, and compressive and tensile strength, that should be optimized to meet the technical, economical, and operational requirements.
This paper details the designing of cement systems for SAGD application and its rigorous testing by simulating downhole conditions. A fit-for-purpose slurry was designed that is chemically stable at the downhole temperatures and able to withstand the thermal stresses.
The optimized slurry was subjected to thermal cyclic loading in an experimental setup designed to simulate downhole conditions, and the performance was evaluated. The cement sheath was intact after being subjected to several thermal loadings. No cracking or de-bonding was observed.
In this paper, the experimental setup, slurry design, testing procedure, and the results are discussed in detail. The discussions presented in the paper should help the industry in constructing and operating SAGD wells safely and economically.
Optimizing Petrophysics Practices through Intelligent Tools Integration
Authors: Al-Harbi Wael , Zahdan Ghassan , Labban Marwan , Rihabe Salim , Husain Kamran , Al-Mushirfi Osama 
Published: February 2011

Abstract
This paper describes several solutions that are developed to automate several workflow processes for petrophysicists at Saudi Aramco. The objective is to further improve the formation evaluation decision-making process by introducing more efficiency in field development practices and automate certain procedures to comply with Saudi Aramco standards. The solutions provided consist of a combination of smart tools and automated workflows designed to further optimize the formation evaluation business processes.
The Near Real Time Petrophysics (NRTP) system enables formation evaluators to simultaneously monitor multiple rigs efficiently by automating the Quicklook workflow. The system seamlessly integrates with well logs and well survey data streams coming from the field with programmable controls that significantly improve the analysts’ ability to prioritize and process well logs on a daily basis.
Workflow Automated Service for Well Logs (WASL) is a collaboration system that optimizes and streamlines reservoir description well log services. WASL enables collaboration among reservoir description data managers, petrophysicists and supervisors. The WASL Dashboard is a complement application to the WASL application suite which monitors and provides key performance index measures on various levels utilizing interactive data visualization tools. The tool also aids Reservoir Description Division (RDD) supervisors by providing engineer productivity statistics, which is currently being used as a measure for granting an appropriate year-end evaluation with respect to well log analysis completion.
The reservoir operation summary environment (ROSE) provides operation engineers with the ability to retrieve all related well log summary activities from the drilling database and allows for the addition of logging plans into corporate repository for daily executive management reporting.
Coil Shooting on Tulip Discovery: Seismic Processing Challenges, Opportunities and Results
Authors: Buia M. , Vercesi R. , Tham M. 
Published: February 2011

Abstract
The Tulip structure is located offshore Kalimantan (Indonesia) in the Bukat PSC. The area is very challenging from the geophysical point of view due the presence of several unfavourable geological factors, especially in the near surface.In order to address these challenges and improve the reservoir image for the appraisal campaign, eni recorded a circular (Coil) seismic survey in August-September 2008. The processing of the survey is now finished. The circular geometry introduces several differences and new challenges in the survey design, acquisition and processing workflow, compared with traditional marine acquisition. When processing a circular survey, the first challenge is the presence of the noise generated by the cables in continuous turning. The second aspect is the presence of statics related to differences in water velocity during the survey. The third difference with conventional processing is related to the midpoint smearing inside the circles, that makes the application of conventional sail line based processing workflows very difficult. The major challenge related to the Coil geometry is an irregular and high fold that requires proper treatment in order to avoid amplitude inconsistencies and migration artifacts. On the up side, Coil geometry allows the full 3D demultiple tools to work at their best and the same is valid for velocity model building and migration algorithms, due to the large azimuthal content. The positive results achieved to date on the pre-stack depth imaging of Tulip, demonstrate that suitable solutions are available even using conventional algorithms and procedures. New processing / imaging strategies need to be put in place in the future in order to minimize the disadvantages and properly exploit the big advantages of Coil acquisition on Tulip.
A Better Way to Forecast Production from Unconventional Gas Wells
Authors: Valkó Peter P. , Lee W. John 
Published: February 2011

Abstract
This work combines two ideas—the stretched exponential decline curve model and the novel paradigm of data-intensive discovery—to provide a controlled production forecast for any individual tight gas/shale gas well on the basis of data gathered through parameter processing for a large group of wells.. Group production for a large number of wells follows stretched exponential decline behavior of production rates, which we model using the corresponding decline curve model. Compared to the Arps model, the new approach offers numerous advantages; the two most significant ones are the bounded nature of estimated ultimate recovery (EUR) without limits on time or rate, and the straight-line behavior of a recovery potential expression that we introduce. This approach moves production forecasts in tight and unconventional gas fields from individual and subjective curve matching to a new methodology we call "group-data controlled forecast." In terms of the novel stretched exponential decline curve model, the combined process offers statistically more consistent reserve estimates and also provides a potential well monitoring tool.