bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Corrosion Assessment with an EM Casing Inspection Tool
Authors: Brill Thilo Michael , Le Calvez Jean-Luc , Demichel Cindy , Nichols Edward , Bermudez Fernando Zapata 
Published: May 2011

Abstract
A recently introduced electromagnetic (EM) casing-corrosion evaluation tool provides total metal thickness, tubular internal diameter, and defect imaging inside single and multiple casings. Quantitative assessment of ongoing corrosion enables timely mitigation strategies to prevent leaks, environmental damage, or catastrophic failures. This slim tool allows measurements through production tubing, eliminating the risk and saving the cost of tubing removal. It provides a high-resolution casing assessment.
EM assessment uses magnetic fields from induced eddy currents to determine the casing thickness and the inner casing diameter. Receiver coils mounted along the tool axis receive these EM fields to give average metal loss; small pad sensors on 18 arms around the tool perimeter provide an image of local metal loss. The measurement resolution is determined by propagating laboratory-measured noise to uncertainty in the computed casing thickness. These calculations are verified with numerical simulation and field validation.
Advanced signal processing converts the raw data to high-quality logs. Deghosting removes the double responses seen as a defect first passes by the receiver coils and later by the transmitter.
Several field examples show the quantitative, high-resolution assessment of pipe condition. Log examples show detection of casing joints, multiple casings strings, and the presence of corrosion damage in the low- and high-frequency images.
Rheological Transition during Foam Flow in Porous Media
Authors: Simjoo M. , Nguyen Q. P. , Zitha P. L. 
Published: May 2011

Abstract
The flow of nitrogen foam in Bentheimer sandstone cores previously saturated with a surfactant solution has been investigated experimentally. The displacement process was visualized with the aid of a CT scanner. The CT data were analyzed to obtain water saturation profiles at different times. The pressure drops measured over core segments were recorded to determine the foam mobility. It was found that foam undergoes a transition from a weak to a strong state at critical gas saturation of Sgc = 0.75±0.02. This effect could be interpreted successfully in terms of the surge of the yield stress of the foam at this value. It is suggested that a confined jamming is most likely responsible for the mobility transition.
Effect of Temperature, Oil Asphaltene Content, and Water Salinity on Wettability Alteration
Authors: Al-Aulaqi Talal , Grattoni Carlos , Fisher Quentin , Musina Zenfira , Al-Hinai Suleiman 
Published: May 2011

Abstract
It is well known that thermal enhanced oil recovery (EOR) improves recovery by lowering the oil viscosity and so is usually performed in heavy oil reservoirs. Wettability alteration may also occur during thermal EOR in which case it may also affect production rates in light oil reservoirs.
The interaction between crude oil-brine on different rock surfaces as a function of temperature is not well defined. For example, for silicate surfaces some authors reported a complete reversal of wettability, from a predominantly water-wet system at lower temperature to a predominantly oil-wet system at higher temperature, while others found that the degree of water wetness increased with temperature.
In this study, the microscopic behavior, by direct observation, of oil and brine on silicate surfaces at different temperatures up to 60°C was studied. Wetting preference of silica as a function of brine salinity, oil type and temperature has been studied during long time interaction (aging) tests. Four light crude oils of different asphaltene contents and brines of different composition have been used in this work.
The study shows that as the temperature increases, the silicate wettability becomes more oil-wet as the asphaltene content of the crude oil decreases. When asphaltene is removed from a crude oil, the degree of oil-wetness is reduced. Regarding the brine effect, in acidic-lower salinity (NaCl brine) where oil adhesion occurs readily, hysteresis between advancing- receding contact angles is larger than for a neutral pH with high salinity brine. The consequence of these observations in flat surfaces is validated by flowing oil and water through glass micromodels, which provide wettability alteration evidence for lower salinity brine and as temperatures increases.
Inaccessible Drilling Targets and Casing Exits Made Possible by the Alleviation of Excessive Torque and Drag
Authors: McCormick John , Hogg Cliff 
Published: May 2011

Abstract
Extended reach and highly deviated wellbores are becoming more and more commonplace in the oil and gas industry, bringing with them a host of challenges related to many aspects of the well construction process. Multilateral wells are an excellent example of this situation due to the doglegs formed when milling and drilling side tracks, the deviation of the hole, and the necessity of getting equipment to bottom and setting weight down to set and operate that equipment, especially during casing exits. Advanced technology has been developed to drill multilateral wells, but even this equipment can run up against its limitations in extremely challenging wells as operators continue to push the technology envelope. It is in these scenarios that combining technologies can provide the solution to safely and successfully manage downhole operations like casing exits and the drilling and completion of multilateral and extended reach wells.
Such technology combinations can have a significant effect, not only on the ability to achieve far reaching targets, but also on the well construction time required and therefore the overall operational costs. In this paper the authors will focus on the combination of technologies to create multilateral wells in Extended Reach Well (ERW) scenarios where excessive torque and drag effects can adversely impact: Torque and weight while milling – associated with sidetracks through cased hole.Getting tools to target depth.Getting the loads at depth that are required to activate, set or release equipment downhole.
They will review a hollow whipstock multilateral system and sub-based torque and drag reduction tools and present case studies of wells drilled successfully with these technologies, including the creation of the worlds’ deepest known horizontal casing exit.
Modeling and Simulation of Structural Deformation of Isothermal Subsurface Flow and Carbon Dioxide Injection
Authors: El-Amin M. F. , Negara A. , Salama A. , Sun S. 
Published: May 2011

Abstract
Injection of CO2 in hydrocarbon reservoir has double benefit. On the one hand, it is a profitable method due to issues related to global warming, and on the other hand it is an effective mechanism to enhance hydrocarbon recovery. Such injection associates complex processes involving, e.g., solute transport of dissolved materials, in addition to local changes in density of the phases. Also, increasing carbon dioxide injection may cause a structural deformation of the medium, so it is important to include such effect into the model. The structural deformation modelling in carbon sequestration is important to evaluate the medium stability to avoid CO2 leakage to the atmosphere. On the other hand, geologic formation of the medium is usually heterogeneous and consists of several layers of different permeability. In this work we conduct numerical simulation of two-phase flow in a heterogeneous porous medium domain with dissolved solute transport as well as structural deformation effects. The solute transport of the dissolved component is described by concentration equation. The structural deformation for geomechanics is derived from a general local differential balance equation with neglecting the local mass balance of solid phase and the inertial force term. The flux continuity condition is used at interfaces between different permeability layers of the heterogeneous medium. We analyze the vertical migration of a CO2 plume injected into a 2D layered reservoir. Analysis of distribution of flow field components such as saturation, pressures, velocities, and CO2 concentration are presented.
Elastic Properties of Emulsified Acids: Effect of Emulsifier Concentration and Temperature
Authors: Sayed M. A. , Nasr-El-Din H. A. 
Published: May 2011

Abstract
For many years, hydrochloric acid was the main fluid used in carbonate reservoirs well stimulation. Hydrochloric acid has many advantages including high dissolving power and water soluble products, but it also has some disadvantages such as high reaction rate and high corrosivity. There are other acid systems that can be used to minimize these effects; one of the most important systems is the emulsified acid. The emulsified acid offers the advantage of minimum additives and minimum corrosion possibilities. Researchers correlated the droplet size of the dispersed phase (acid) and emulsifier concentration to the viscosity, stability, and reaction kinetics of emulsified acids.
The effect of emulsifier concentration, acid volume fraction and temperature on elastic properties of emulsified acid was not studied before. The main objective of this work is to study the effect of these parameters on the elastic properties of the emulsified acid. In order to perform that, a HPHT oscillatory rheometer was used.
The general behavior of emulsified acid is that the viscous modulus (G″) is always higher than the elastic modulus (G′). As the emulsifier concentration increases, viscosity increases and the viscous behavior dominates for these fluids. As the acid volume fraction increases, the viscous modulus (G″) increases. At low emulsifier concentration (2 vol%), the elastic modulus (G′) and viscous modulus (G″) increase with increasing the temperature up to 170 °F and then decrease. At higher emulsifier concentration, the elastic modulus (G′) almost does not change with temperature and the viscous modulus (G″) always decreases with increasing temperature. These results will help production engineer to better design acid treatments that depend on emulsified acids.
Valhall – Pushing the Limits for Openhole Zonal Isolation — Qualification and Field Trial of 10,000-psi Oil-Swelling Packers
Authors: Koløy Tom Rune , Andersen Kristian , Nijhof Jeroen 
Published: May 2011

Abstract
BP-Norge AS operates the Valhall Field in Norway and relies on multi-zone water injection for reservoir management and control of unwanted water production for Valhall wells. A produced water shutoff method in this field is necessary, and equipment must be capable of maintaining integrity at differential pressures of 10,000 psi during prop-fracture stimulation of the individual zones in the oil-producing wells. The operator wanted to find a new completions solution that would enable long horizontal reservoir sections to be completed and stimulated with the capability to shut-off unwanted water at a later time during well life.
Swellable elastomer packers (SEPs) were suggested to the operator as a possible method for zonal isolation. Unfortunately, three attempts to qualify the currently available SEPs to the 10,000-psi differential pressure (DP) for Valhall were all unsuccessful; therefore, the decision was made to try a new design that used an innovative mechanical end-ring system. This configuration uses a solids-laden oil-based mud (OBM) to expand the element installed on the outer surface of the basepipe that forms part of the reservoir liner. This eliminated the need to spot dedicated swelling fluid.
The changed configuration represented a significant step change in the design methodology of SEPs. The new design not only enabled the reduction of element length and packer OD, but it also could withstand the high DP ratings as well as increased the DP ratings of long SEPs. The new configuration required qualification testing, and this paper presents the case history of the operator's full-scale qualification testing up to 10,000 psi across two 5-meter packers as well as the improvements the new SEPs could offer over previously used equipment and methods.
The paper will also discuss the design, other potential applications, and the advantages of the new SEP design. A case history of the first installations of the new SEP worldwide will be presented as well.
Effects of Rapid Gas Decompression on Swellable Rubber and Common Oilfield Rubber Compounds.
Authors: Young Dustin , Sevre Alf K. , Smith Peter E. , al-Madlouh Mohammed , Awang M. Zaki 
Published: May 2011

Abstract
Rubber or elastomeric seals are flexible polymers used in a variety of applications in many industries and have become more widely used in oilfield equipment as polymer technology has advanced. The seals are used in many oilfield applications and can be damaged during a rapid decrease of pressure after being exposed to environments containing gas. This phenomenon is known as explosive decompression (ED) or rapid gas decompression (RGD).
RGD damage can be manifested as splits, cracks, or bubbles in the seals, depending on the rubber type, length of exposure to the gas, and the rate of pressure decrease. Damage caused to a seal by RGD can range in severity from a slight weakening of the physical properties of the rubber to a catastrophic failure of the integrity of the seal. Both surface operations and downhole conditions are capable of causing RGD, which, can result in failure of the equipment using the seals.
This paper discusses tests performed on various elastomeric samples, including swellable rubber, to determine the effects that RGD will have on the seals under varying conditions. The tests exposed each sample to a range of pressure drops and gas exposure times. The samples were analyzed after each test for physical changes and signs of RGD damage. The purpose of mapping the effects of RGD on multiple samples and the various conditions to which the seals were subjected was to develop a better understanding of the conditions leading to RGD damage and to identify operations at risk for causing RGD damage to elastomeric seals. The testing and results are further discussed in this paper.
Coreflood Study of Low Salinity Water Injection in Sandstone Reservoirs
Authors: Nasralla Ramez A. , Nasr-El-Din Hisham A. 
Published: May 2011

Abstract
Water chemistry has a significant effect on oil recovery. It was found that low salinity water has a good potential for improving oil recovery in sandstone reservoirs. However, the mechanisms by which low salinity water injection works are still uncertain. This means the optimum conditions for improving oil recovery are unknown. In this paper, coreflood experiments were conducted to understand how cation type in injected water may affect oil recovery. In addition, testing multiple salinities helped to identify the optimum salinity.
Several waterflood experiments at high pressure-high temperature (HPHT) were conducted on Berea sandstone cores, 6 in. length. Single cation water solutions were prepared to be injected in cores at different concentrations of NaCl, CaCl2, and MgCl2. Effect of oil composition and characteristics on improvement of oil recovery by waterflooding was investigated by using two different types of crude oils. In addition, core effluent fluid was collected and analyzed using ICP-OES and Spectrophotometer to study interactions between rock and injected fluid.
This work contributes to the understandings of impact of cation exchange on oil recovery by low salinity water flooding. Experiments showed that exchanging certain cations is the primary reason of higher oil recovery. Absence of Ca2+ in injected water allowed water to leach Ca2+ from the rock surface which, caused surface instability and allowed higher oil volume to be released from the rock surface and be recovered. Results demonstrate that the existing cations in the injected water solution have more dominant effect on oil recovery than the concentration of salts in water. In addition, oil composition has a significant effect on the efficiency of waterflooding, and hence oil recovery. These findings help in introducing the optimum water salinity.
First Successful Multilateral Well Logging in Saudi Aramco: Innovative Approach toward Logging an Open Hole Multilateral Oil Producer
Authors: Al-Momin Ali , Zeybek Murat , Azrak Abdul Wahab , Burov Anton 
Published: May 2011

Abstract
Drilling of multilateral wells has increased significantly over the past few years as one of the reservoir development strategies to maximize well productivity through maximizing reservoir contact (MRC). These complex wells impose big challenges with respect to well accessibility for rigless well intervention. Means to access those wells were developed to perform conventional coiled tubing (CT) operations, such as reservoir stimulation.
One of the existing challenges is to perform production logging in these complex wells to quantify oil and water contribution of each open hole lateral and pinpoint fluids entry, mainly deep water inside these laterals.
This challenge was encountered in a multilateral oil evaluation producer, which was drilled in a carbonate oil reservoir but died shortly after being put on production due to high water production from an unknown source. This necessitates the logging of each of the well's laterals to identify the water contribution intervals to allow for the proper remedial action on this well, as well as to determine the optimal well completion for this type of reservoir, including inputting to geological modeling.
At present, there is no single production logging tool (PLT) that can be utilized to log each lateral selectively. Therefore, a combination of a multilateral tool along with a reservoir saturation tool was utilized to locate and access laterals selectively and to record a pulsed neutron log to determine the produced water velocity across each of the laterals. The pulsed neutron log was combined with three phase hold-up logs allowing the generation of production profiles of each lateral as well as the detection of water entries across these laterals.
This paper discusses the planning, execution and results evaluation of the logging job on an openhole multilateral oil producer along with all the techniques, which were employed to overcome challenges encountered along the way to acquire the best possible data on each lateral.
Multi-Physics Approach for Aging Assessment of Carbonate Rocks
Authors: Pairoys F. , Al-Zoukani A. , Nicot B. , Valori A. , Ali F. , Zhang T. , Ligneul P. , Akbar M. 
Published: May 2011

Abstract
Wettability influences the flow motion of hydrocarbons in carbonate oil reservoirs: it is measured in laboratory with specific procedures including assessment of its initial value. Conventional or special core analysis requires good cleaning of the cores. Additional measurements like relative permeability or capillary pressure for instance require restoration of the initial wettability conditions of cores by aging them. The routine methods for assessment of wettability are USBM and Amott-Harvey (A-H) tests, which involve large amount of efforts and time. In this study we replace these tedious processes by tracking the aging through repeated NMR and resistivity measurements.
Four core plugs, two dolomites and two limestones, were selected from twenty carbonate plugs collected from different outcrops. After saturating the samples with brine, the cementation factor m was calculated. NMR T2 relaxation was performed as a reference on fully brine saturated samples. Crude oil was injected into the plugs until they attained Swi. An NMR T2 was measured on them before aging. Then one limestone and one dolomite were immersed in crude oil and placed in an oven at reservoir temperature, while the two other samples were loaded in resistivity core holders under same reservoir temperature and confining pressure to age them. Resistivity was measured continuously while NMR T2 were recorded at different time intervals to observe the response of the aging core samples to independent physical investigations.
The NMR and resistivity measurements were used to identify the wettability alteration. The resistivity change showed a continuous wettability change in the plugs, which was also confirmed by the continuous change in the NMR T2 response. Both methods showed that dolomite was more prone to becoming oil-wet than limestone. It was verified by USBM and Amott-Harvey tests on same plugs. Further tests will be necessary to validate the generality of the overall workflow.
A Simple Analytical Formula to Estimate Fracture Connectivity
Authors: Ozkaya Sait. I. 
Published: May 2011

Abstract
A simple expression is derived for average fracture intersections per fracture, λ as the product of fracture density, average length and angular standard deviation for 2D and 3D cases. The calculated λ value quite accurately estimates the observed actual λ values for a variety of cases including one or two fracture sets, truncated or not-truncated fractures, and log normal or power length distribution. The validation is confined however only to 2D stochastic fracture models. The 3D equivalent formulae were not validated. The formula fails to estimate number of fracture intersections accurately when fractures are clustered. Fracture clusters could either be fault related fracture corridors or highly fractured layers. In either case, it is necessary to calculate λ for each fracture corridor or each fractured layer with different fracture density.
The relationship between λ and fracture connectivity and percolation were investigated using several stochastic fracture models. λ seems to be a reasonably good estimator of fracture connectivity, which we define as percent of fractures within the largest fracture cluster. The relationship between number of fracture intersections and percolation threshold is, however, weak because percolation threshold is dependent on the relative length of fractures with respect to the distance between two opposite ends of a fractured medium.
We tested the value of λ from borehole image data as a measure of fracture connectivity by comparing it with open hole log and production flow profile in an actual well. λ was calculated for highly fractured low porosity layers and found to be far below the values expected for fracture connectivity. Production log flow profile and open hole logs confirmed the result. There is no flow from the fractured low porosity layers, but all the flow is from a high matrix porosity / permeability layer with sparse or no fracturing. Open hole logs also show injection water encroachment only within the permeable matrix layer.