bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical and Experimental Investigation of the Motion of Multiphase Fluids Containing Paramagnetic Nanoparticles in Porous Media
Authors: Ryoo Seungyup , Rahmani Amir R. , Yoon Ki Youl , Prodanovic Maša , Kotsmar Csaba , Milner Thomas E. , Johnston Keith P. , Bryant Steven L. , Huh Chun 
Published: February 2011

Abstract
Paramagnetic nanoparticles are potentially useful for formation evaluation and reservoir monitoring, as they can be induced to move by an imposed magnetic field. Nanoparticles can be designed to have long-term dispersion stability in brine with minimal retention in reservoir rock and with preferential adsorption at oil-water interface. When exposed to magnetic field, they generate sufficient interfacial movements for external detection.
When paramagnetic nanoparticles are either adsorbed at oil-water interface or dispersed in one of two fluid phases co-existing in reservoir rock pores, and exposed to external magnetic field, the resultant particle movements displace the interface. Interfacial tension acts as a restoring force, leading to interfacial fluctuation and a pressure (sound) wave. Our previous work (Prodanović et al, 2010) provided theoretical explanations for the motion of the interface between a suspension of paramagnetic nanorods and a non-magnetized fluid in a cylindrical dish, as measured by phase-sensitive optical coherence tomography (PS-OCT). Here we report on additional experiments carried out with a range of in-house synthesized and surface-modified iron-oxide nanoparticles. The numerical method was improved to be volume conserving for more quantitative matching.
The measurements of interfacial motion by PS-OCT confirm theoretical predictions of the frequency doubling and the importance of material properties, such as magnetic susceptibility, for the interface displacement thus offering insights into behavior in real porous media. With the combined experimental and modeling work, strategies for improved nanoparticle design are developed so that the interfacial, thereby acoustic, response can be magnified.
This laboratory and modeling study is an important step to develop a magnetic field-based method for an accurate, non-invasive determination of multiphase fluids distribution in reservoir rock.
Observations of Thermal and Pressure Transients in Carbon Dioxide Wells
Authors: Paterson Lincoln , Ennis-King Jonathan , Sharma Sandeep 
Published: February 2011

Abstract
Carbon dioxide wells are different to oil, gas and water wells because large density changes due to transient thermal effects can decouple surface pressure from downhole pressure. This means, for instance, that wellhead pressure can decline while reservoir pressure is building after shut-in of a production reservoir. Similarly the opposite can occur. This presents challenges for the interpretation of surface measurements.
An ability to forecast wellhead pressure is desirable for the optimum design of surface facilities for both carbon dioxide production and injection. The interpretation of surface measurements is also useful for monitoring carbon dioxide reservoirs as flow rates are more easily measured at the surface, and surface gauges are more easily replaced if a gauge fails.
Here we report on detailed pressure and temperature observations involving a mixture of 77 mole % carbon dioxide, 20 mole % methane and 3 mole % other gas components. The measurements are from two wells, one production and one injection, involving both surface and downhole gauges. These two wells when connected can act as a strong siphon due to thermal effects. Thermal transients are observed to last up to two months before the surface response matches the downhole response. The use of two downhole gauges in the injection well allows measurement noise to be separated from real pressure events. This in turn allows the performance of the downhole gauges to be evaluated.
The results are useful for input into the engineering design of future carbon dioxide facilities and the use of surface pressure for interpreting reservoir behavior.
4D Seismic History Matching of a Real Field Case with EnKF: Use of Local Analysis for Model Updating
Authors: Fahimuddin Abul , Aanonsen Sigurd Ivar , Skjervheim Jan-Arild 
Published: February 2011

Abstract
Quantitative incorporation of 4D seismic data into reservoir history matching is an attractive proposition. The use of ensemble Kalman filter (EnKF) in this regard improves overall quality of seismic data matching and estimating reservoir parameters. We performed 4D seismic history matching of a sector model based on a North sea reservoir using real inverted 4D impedance data. Special challenges are involved when we assimilate large amount of in EnKF, and hence, a methodology based on a combination of global and local analysis scheme is used. In history matching process, we have focused on matching the acoustic impedance ratio between two time steps of several years of production. A petro-elastic modeling based on rock physics recipe of North sea reservoir is used. Uncertain reservoir parameters considered are porosity and permeability. Updated dynamic variables (pressure and water saturation) are conditioned to both production and seismic data. The large number of measurements introduced by the integration of 4D seismic data is handled by an efficient EnKF scheme with the possibility to perform localization. Global and local analysis schemes assimilate production data and seismic data respectively. In our implementation of local analysis, we used three significant regions based on flow conditions and seismic data within a given local analysis region is influenced by only variables in the same region. The posterior ensemble of models showed good match to both production data and seismic data. In most of the cases of reservoir characterization, the combined use of 4D seismic with production data improved history matching for the wells and also improved posterior impedance ratio data matching. In addition, 4D seismic data provided more information related to permeability update in the aquifer and in-fill areas. The results indicate that the proposed local analysis-based model updating scheme reduced the amount of spurious correlations and tendencies to ensemble collapse seen with global analysis.
Continuous Pig Lift: A New Artificial Lift System and Its Field Pilot Test
Authors: Zhong Haiquan , Li Yingchuan , Yu Xin , Wang Zhibin 
Published: February 2011

Abstract
Pig lift was firstly proposed and successfully applied in five wells in Brazil in 1996. Pig lift exhibits many advantages over other artificial lift systems, particularly for the wells with high viscosity oil, waxy oil, high gas-liquid ratio, low pressure and/or low productivity. However, one of its biggest restrictions is that the well has to use a U-shaped double completion string if a pig lift system will be installed, as a result, it is impossible to effectively use formation gas for lifting, and a high-pressure gas resource is needed. In addition, pig lift as an intermittent production method requires well periodical opening and shutting-in, which limits well productivity and increases management difficulties.
This paper develops a new artificial lift system, continuous pig lift, by the use of a single completion string with a series of eccentric units. Retaining all the advantages of the current pig lift, the new system allows the pig to fall from the annulus between the tubing and casing down to the downhole tubing coupling. A valve device is designed to cut off both high and low pressures in the wellhead and launch the pig. With no need of extra gas resource, this system effectively uses formation gas to push the pig into production string and achieves continuous production.
The developed system was installed in one well in Sichuan Gas Field of China. The system is stable and has significantly increased production rate in comparison with conventional continuous gas lift. Through various field pilot experiments, pig size, type and launching frequency are found to be key factors dominating the performance of a continuous pig lift system and the optimum values of those factors are then determined.
HZ 25-4 ERD Challenging Drilling Project - New Strategy and New Technology Implementation Are the Keys to Improved Drilling Performance
Authors: Hong Lian Ji , Scaruffi William , Brewster T Wayne , Balka Sarfraz M. 
Published: February 2011

Abstract
CACT-OG is a joint operating company consisting of CNOOC, ENI, and Chevron as its Principal Companies. CACT- OG is the operator of Huizhou HZ 25-4 oilfield in South China Sea, which was discovered in December of 2005 as multiple oil bearing zones found in the vertical exploratory well drilled by a semisubmersible rig. HZ 25-4 field is located in block 16/19 in central area of Pearl River mouth basin, located 6 km southwest of the HZ 19-2 platform in a water depth of 102 meters. After discovery, extensive studies were conducted for the development of this field. It was decided to upgrade the existing drilling rig on the nearby HZ 19-2 field platform and drill extended reach (ERD) wells from the platform. Three of five ERD wells were drilled and completed with 6" horizontal laterals and stand alone screens for sand control.
A number of challenges appeared while drilling these wells including: ERD drilling experience level, excess torque and drag, hole instability, hole cleaning and resulting pack off, high side force and casing wear, high ECD due to shallow TVD, losses due to high ECD and fault encounter, and shock and vibration. The result of these challenges was long times to complete the wells and excess budget overruns. After the completion of the third well, it was been decided to suspend the operations and perform detailed analysis on the challenges with extensive lessons learned in order to approach the remaining two ERD wells in the Plan of Development with a different strategy.
Following the studies and drilling analysis, the revised final plan included a new engineering design, revised operations procedures and monitoring, new approach for team building and training, and implementation of newer technologies such as utilization of Aluminum Drill Pipe and Continuous Circulating Devices. The result of the new plan applied has been a dramatic improvement in performance and consistent savings in budget. It has been observed that this different drilling approach and technology has opened a new window on how to drill challenging ERD, and that is a key to improved drilling performance.
Analytical Tools Aid Understanding of History-Matching Effort in a Fractured Reservoir
Authors: Kabir C. S. , Boundy F. 
Published: February 2011

Abstract
Many equiprobable solutions exist while history matching a reservoir's performance, given the ill-posed nature of the inverse problem. To mitigate some of the uncertainty issues stemming from the initial static reservoir description, this study shows how continuous learning evolves when a slate of analytical tools are used while interpreting real-time surveillance data. The combined approach involving the use of analytical tools in conjunction with numerical simulations helps understanding reservoir performance, which, in turn, allows insights into history matching. Specifically, we demonstrate the use of various analytical tools to learn about (a) time-dependent behavior of both producers and injectors with rate-transient analysis to assess an evolving waterflood, (b) reservoir heterogeneity with pressure-transient analysis, (c) degrees of time-variant injection support with the reciprocal-productivity index, (d) injector-producer connectivity with the capacitance-resistance model, and (e) real-time injection-well behavior with the modified-Hall analysis.
The benefits of collective use of analytic tools demonstrate that they should be used either simultaneously or preferably before undertaking a detailed numeric flow-simulation study, particularly where real-time data are being gathered. In particular, the lack of performance match for the entire history with a numerical model becomes transparent when the learning from analytical tools is juxtaposed. This understanding paves the way for much improved learning of reservoir plumbing.
Crosswell Electromagnetic Inversion Constrained by the Fluid-Flow Simulator
Authors: Liang Lin , Abubakar Aria , Habashy Tarek M. 
Published: February 2011

Abstract
Crosswell electromagnetic technology has been developed for reconstructing the formation resistivity distribution of the subsurface. By looking at the resistivity changes over time, one can monitor the fluid front movement and estimate saturation changes in the reservoir. Traditionally, the resistivity distribution is directly inverted from the crosswell electromagnetic data through an inversion process. However, this inversion process can be non-unique and has limited spatial resolution.
In this paper, we introduce several inversion approaches for improving the interpretation of the crosswell electromagnetic data. The inversion is constrained by a multiphase fluid flow simulator that models the fluid flow in the reservoir and constructs the spatial distribution of the water saturation and salt concentration, which are in turn transformed into the formation resistivity using a resistivity-saturation formula. In these approaches, instead of directly inverting the resistivity distribution, we invert the formation petrophysical parameters such as permeability and porosity.
Three inversion approaches were explored. The first is the model-based approach that inverts a layer-by-layer distribution of permeabilities and porosities. The second is the pixel-based approach in which we assume that the formation permeabilities are known and hence we invert only a cell-by-cell distribution of porosities. The third is a hybrid approach in which we invert a cell-by-cell distribution of porosities together with a layer-by-layer distribution of permeabilities. By using these approaches, we obtain a reconstructed resistivity distribution that is consistent with the fluid flow physics, and the spatial resolution is significantly improved. Additional outcomes of the inversion include the saturation spatial distribution, which provides an explicit indication of fluid movement within the reservoir. The results of synthetic case studies show significant improvements compared with those acquired by the traditional approach.
Joint History Matching of Production and 4D-Seismic Related Data for a North Sea Field Case
Authors: Gervais V. , Roggero F. , Feraille M. , Le Ravalec M. , Seiler A. 
Published: February 2011

Abstract
This paper shows the results of an assisted history-matching process applied to a North Sea field case operated by Statoil. The dynamic data considered, that is the data varying with fluid flow, are both production data and 4D-seismic related data.
The history-matching process entails a geology to fluid-flow simulation workflow, including the population of the geological model by facies and petrophysical properties using geostatistical algorithms, the simulation of fluid saturation and pressure changes in the reservoir and the computation of time-lapse seismic attributes. This workflow also addresses scaling issues: upscaling of petrophysical properties from the fine geological grid to the reservoir coarse grid; pressure and saturation downscaling from the reservoir grid to the geological grid where a petro-elastic model is applied to compute the seismic related attributes. A least-square objective function is defined to measure the mismatch between the measured dynamic data (production and 4D seismic-related data) and the corresponding simulated responses. Then, a gradient-based optimization algorithm is run to minimize this function, perturbing parameters identified as uncertain from a preliminary sensitivity study based upon Morris's method. To ensure the overall consistency of the workflow, the perturbations applied to the selected parameters are propagated all along the workflow.
This methodology was applied to a North Sea field case. A good production data match was obtained perturbing the spatial distribution of some facies and petrophysical properties. The implemented perturbation process was driven by the gradual deformation method: many likely distributions were combined all together leading to a more suitable distribution, which still honored the statistical properties of the model. The match of the available 4D seismic-related data was also locally improved. In addition, the use of 4D seismic data on top of production data made it possible to reduce the data misfit at some wells.
This study shows the ability of the assisted history-matching process to handle both production and 4D seismic data on a real field case.
Advanced Technologies and Practical Guidelines for Challenging Drilling Applications
Authors: Jellison Michael , Spoerker Hermann , Chandler R. Brett , Abashin Valentin 
Published: February 2011

Abstract
This paper provides a review of recent technology advancements and addresses practical considerations associated with drillpipe and drill stem components for extreme drilling applications. Ultra-high torque double-shoulder rotary connections are often employed in these applications potentially complicating proper design and material selection for cross-overs, top-drive subs, pup joints and other accessories. These new connections often employ materials with higher strength requirements than standard API connections. The paper outlines recommendations for material strength and design parameters for various drills stem accessories. The latest generation of high angle and extended reach wells are encountering significantly higher side loads between the drillpipe and casing creating unprecedented levels of casing wear. Proper hardband selection, application and maintenance are essential to successfully and safely drill these critical projects. Hardband system trends for critical applications are highlighted, and recent hardband casing wear and tool joint protection test results obtained using an advanced hardband wear machine are discussed.
Due to the dramatic increase in oil prices the industry has seen a re-emergence of deep and ultra-deep drilling projects that encounter H2S gas. The paper provides an update on the latest sulphide stress cracking resistant drillpipe grades along with initial results from a study of the effect on S-grade drillpipe samples to various H2S exposure concentrations, representing typical conditions when circulating a gas kick to surface. Sour service drillpipe, built with SSC resistant upset tubes and tool joints, has been available for some time. The friction welds joining the upset tubes and tool joints were not resistant to SSC. This paper presents the successful development and qualification of SSC resistant friction welds for critical sour applications. The surge in critical drilling has led to an increasing trend of drill stem friction heating failures. The paper includes characteristic features of these failures along with case histories and prevention methods.
Automated Field Development Planning in the Presence of Subsurface Uncertainty and Operational Risk Tolerance
Authors: Tilke P. G. , Banerjee R.. , Halabe V. B. , Balci B.. , Thambynayagam M.. , Spath J.. 
Published: February 2011

Abstract
This paper presents an automated workflow to accelerate the well placement planning process in the presence of subsurface uncertainty and operational risk. The system allows the user to screen and rank development options in minutes.
This automated field development planning system is an optimization application, integrated with a larger seismic-to-simulation workflow. A key piece of technology in this system is a high-speed semi-analytical reservoir simulator, which enables an optimal strategy to be computed very rapidly. The system also embeds key technologies for optimization in the presence of uncertainty and risk which leverages an advanced uncertainty framework.
The workflow starts with a reservoir model, along with existing wells and other operational constraints. Oil or gas production is computed using the high-speed reservoir simulator. Proposed well trajectories honor operational constraints, such as facility processing, water injection capacity, borehole dogleg severity, anti-collision with existing wells, and hazard avoidance on the surface and in the reservoir. The optimal strategy proposes well surface locations, trajectories, and completion locations and is calculated by optimizing the value e.g., net present value (NPV) or production.
This new methodology has many applications in the field development planning context. We are able to rapidly screen multiple field development planning scenarios and produce an optimal new/infill drilling strategy with primary production or waterflooding consisting of both newly proposed and existing wells. The final result includes performance predictions based on an optimized field development plan (FDP), risk, and subsurface uncertainties. The most promising scenarios can if necessary be used subsequently for detailed numerical simulation in order to validate results.
The value of this automated field development planning workflow, along with support for pattern, pad, and platform based strategies, is proved by its use on a variety of onshore/offshore mature and green oil and gas fields with wells in primary production and waterflooding environments.
Multiple-Opening Diverter Tool Reduces Formation Surge Pressure and Increases Running Speeds for Casing and Liners
Authors: Scott Thad , LoGiudice Michael , Gaspard Greg , Vidal Daniel 
Published: February 2011

Abstract
When running casing in deepwater/subsea applications or in liner deployments, excessive surge pressure in the wellbore can occur when drilling fluid in auto-filled casing is forced through the drillpipe landing string to surface. The resulting friction losses can increase the equivalent mud weight (EMW) sufficiently to exceed the fracture gradient of the formation and often results in fluid losses that could lead to well-control issues. Surge reduction tools mitigate this problem by introducing ports in the drillpipe above the casing or liner running tools. The auto-filled fluid can then be diverted through the ports into the annulus, allowing the casing or liner to be run much faster without the risk of surging the formation excessively. Until recently surge tools have been run in the open position, allowing the tool to divert fluid at all times; however this prevents circulation in the event that the casing or liner needs to be washed down upon encountering an obstruction downhole. Furthermore, should a well-control situation occur, the tool must be closed permanently by intervention from surface and can no longer divert fluid once wellbore control is achieved.
To address this shortcoming, a multiple-opening diverter tool has been developed that is initially run into the wellbore in the closed-port position, allowing the system to have complete pressure integrity. The ports are covered by an unbalanced sleeve, which, as auto filling occurs, is opened by a small differential pressure created within the tool, diverting fluid as necessary. Once auto filling stops, the sleeve returns to its original position, and the ports are automatically closed off, enabling the string to be circulated without permanently deactivating the tool. In addition, the ports remain closed should a well-control situation occur.
In this paper the authors will review the evolution of casing fill control equipment, discuss the issue of controlling losses while running a tubular, and describe the features of this new multiacting surge-control tool. They will conclude with a case study of its use and effectiveness.