bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Upscaling Fracture Corridors- Uncertainties
Authors: Ozkaya S. I. , Bolle L. 
Published: December 2007

Abstract
This short paper presents an overview of some critical issues related to fracture modelling and upscaling, using as an example, borehole image data from a carbonate field in the Middle East.
Relationship between fracture density and mechanical layer characteristics is common knowledge. A fundamental question is whether fracture-prone units have a larger number of fracture corridors and mega-fractures. Fracture corridor spacing may be large controlled by the fault size and is independent of mechanical layers. Alternatively, the spacing of fracture corridors and mega-fractures may be controlled largely by mechanical layer characteristics to a large extent. In this Field, the fracture prone units seem to have higher number of fracture corridors and mega-fractures than less fracture- prone units.
One important step in fractured reservoir characterization is estimating the percentage of fracture fairways (fault zones) detectible from seismic data. Without such an estimate, fracture models can only yield a global history match and can not be used for well-planning. The importance of mapping fracture fairways is high when the fracture corridors are much clustered in fracture fairways and fault zones. For a low degree of clustering, it may not be so important to locate all fracture fairways, since fracture corridors will be widely spread with a low degree of connectivity. Fracture analysis showed that seismic fault maps show only half of fracture fairways and small faults that are present in this field. The remaining half of the faults must be generated stochastically and used in stochastic fracture corridor discrete and upscale models along with actual seismic faults. Introduction of stochastic faults poses a serious challenge to reservoir simulation because classical history match procedures can no longer be used to evaluate a fracture model.
An Accurate Set of Correlations for Calculating Critical Properties and Acentric Factors for Single Carbon Number Groups
Authors: Al-Meshari Ali A. , McCain William D. 
Published: December 2007

Abstract
In order to describe the phase behavior of a reservoir fluid and calculate its volumetric properties, an EOS requires the values of critical pressure, critical temperature, and acentric factor for each component. There are several correlations in the literature for calculating critical properties and acentric factor for each single carbon number group, SCN.
For heavy ends, accurate properties can be predicted with accurate representation of the critical properties and acentric factor. Direct measurement of the critical properties for heavy ends is not practical. So, characterization of the heavy ends is required.
In tuning EOS after splitting the plus fraction and assigning critical properties and acentric factor for each SCN group, the saturation pressure for the reservoir fluid will be matched at reservoir temperature using the extended composition. Since the experimental measurement for the molecular weight of the plus fraction has some uncertainty, it is reasonable to use the molecular weight of the plus fraction as the tuning variable for matching saturation pressure with the extended composition.
The critical properties and acentric factor for each SCN group extended from the plus fraction were calculated using six different sets of correlations, as discussed above. The main objective of testing these different sets of correlations is to find the set of correlations that will lead to the least adjustment for the molecular weight of the plus fraction when the measured saturation pressure is matched using the extended composition. Results show that using Cavett correlation for calculating critical properties and Riazi and Al- Sahhaf correlation for calculating the acentric factor will lead to the least adjustment in the molecular weight of the plus fraction when saturation pressure is matched with the extended composition.
Simulation of Underground Natural Gas Storage in Sarajeh Gas Field, Iran
Authors: Khamehchi E. , Rashidi F. 
Published: December 2007

Abstract
One of the main concerns in Tehran during winter is the pressure drop in gas transfer lines which leads to shortage in gas supply to the northern part of the city located in higher altitude. To deal with this problem, National Iranian Gas Company (NIGC) decided to store gas in nearby natural reservoirs during hot season and produce it during cold season. Sarajeh gas condensate reservoir, located 145 Km far from Tehran, was considered for underground gas storage (UGS) to deal with gas demand in Tehran.
First, the significance of UGS, different types of reservoirs considered for UGS and its history are presented; next, coarse grid model of the reservoir is built; simulation and history matching of Sarajeh gas field are introduced and briefly discussed and finally conclusions and recommendation for future work is presented.
Based on available information and those generated by the model, this field could be a candidate for UGS plan. The results showed that two horizontal and one vertical gas production wells need to be drilled to achieve pressure drop in the reservoir and deliver 150 MMSCF of gas per day including production from existing three gas producers. Reservoir performance after history matching using depletion scenarios is predicted and depletion last for 4.5 years. Ultimate recovery factor is 65% for gas and 40% for gas condensate. Following reservoir depletion to approximately 2400 Psi, gas injection cycles in 6 months during hot season with the injection rate of 160 MMSCF per day and gas production cycles in 5 months in cold season with the rate of 175 MMS per day can start. Total gas volume stored in each cycles is approximately 1 × 1012m3.
Increasing Oil Recovery of Channel Sandstone Reservoirs with Extra High Water Cut by Using Horizontal Wells
Authors: Bo Liu , Xin Liu 
Published: December 2007

Abstract
Salaxing oilfield of Daqing has been developed for more than 40 years and has entered the high water cut late development stage. The reservoirs are large lacustrine luvial delta facies with multi-layers, heterogeneity is serious, watered-out degree of the reservoirs are extremely uneven, remaining oil distribution is complicated too, but its potential to produce oil is still high, and is mainly concentrated in the thick reservoirs of sandstone sediment origin. To produce the remaining oil in the thick reservoirs, the currently used ways are selective perforation, deep profile modification, selective position fracturing etc., and the currently used methods are infill drilling, polymer flooding etc. However, the use of these ways and methods in vertical wells can't completely produce the remaining oil inside the thick reservoirs. This paper provides an example of a successful horizontal well with a horizontal section of 650 m and production rate of nearly 100 t/d, which is drilled in channel sandstone of 7 m (of which the lower part has been watered-out to a medium ~ high degree) with the remaining oil bearing thickness of only 3 m. The key technologies are lateral accretion interlayer prediction technology by detailed reservoir description, accurate remaining oil description to avoid the watered-out section of the horizontal well, and optimally perforation technology for horizontal well. This indicates that drilling horizontal wells in Salaxing oilfield of Daqing can increase the oil recovery of channel sandstones reservoirs with extra high water cut.
Enhanced Petrophysics: Integration of Core and Log Data for Improved Reservoir Saturation Monitoring
Authors: Ma S. Mark , Al-Hajari A. A. , Kersey D. G. , Funk Jim J. , Holmes K. , Potter G. 
Published: December 2007

Abstract
Oil migrating into a water saturated reservoir is a drainage process while waterflooding an oil reservoir is a water imbibition process. Many factors affect drainage and imbibition rock properties including pore structure, rock surface properties (lithology) and their interactions with pore fluids (wettability), and fluids displacement processes. Difference in drainage and imbibition is significant and this difference should be considered, but is often neglected, in reservoir saturation monitoring (RSM).
In this study, fundamentals of rock properties and their interactions with oil and water were reviewed. In a specially designed laboratory special core analysis program, both drainage and imbibition rock properties were measured in the laboratory, at reservoir conditions, using reservoir rock samples, crude oil, and synthetic brine. Wettability was restored by aging the rock samples in crude oil at temperature. Pore structure was characterized by integrating capillary pressure and petrographic studies. Rock lithology was determined by X-ray diffraction measurements and thin section examinations. All laboratory measurements were integrated to better understand drainage and imbibition rock properties.
In applying the laboratory determined rock petrophysics to field RSM, time-lapse resistivity logs were used to identify the current dynamic water-oil contact (DWOC). Above this DWOC, drainage rock properties were used for log processing while below this contact imbibition rock properties were used. Field examples are shown to demonstrate the applications of drainage and imbibition petrophysics in evaluating waterflood sweep and identifying intervals for potential side-tracks.
Efficiency of Vertical Gravity Separators in Gas Liquid Applications
Authors: Noui-Mehidi M. N. , Albarran M. Rivero , Wu J. 
Published: December 2007

Abstract
This paper is concerned with a study of the efficiency of vertical separators intended to gas liquid applications. A compact configuration of coaxial cylinders in which a multiphase flow is vertically flowing can achieve gas liquid separation by the use of gravity in a certain range of gas-liquid flow rates. With this method the separated liquid can be collected in the lower part of the system without any gas carry under. The stability limit of such separators has been identified regarding the inlet conditions and the geometry of the system.
Experimental Study on Additives Systems Used for Proppant Flowback Control in a Hydraulic Fracturing Treatment
Authors: Alqam Mohammad H. , Abass Hazim H. , Khan Mirajuddin R. , Caliboso Edwin T. 
Published: December 2007

Abstract
The use of proppant combined with various additives, as a mean to control proppant flowback in propped hydraulic fracturing treatments, has gained a wide support in the industry. A screenless hydraulic fracturing treatment has been applied as an acceptable completion strategy to mitigate sand production and/or production increase in non-associated gas reservoirs in Saudi Arabia. Understanding the parameters that maximize the life of propped hydraulic fracturing applications is very crucial in controlling sand production and maximizing gas/oil production.
This paper discusses the roles of closure stress, temperature, curing time and carrier fluids in attaining a maximum strength of the new systems compared to other additives following a propped hydraulic fracturing treatment. Also, the conductivity of RCP by itself and in combination with other additives has also been evaluated.
The study results showed that all the independent variables play important roles in achieving an appreciable increase in compressive strength of the new system in comparison with other additives. Also, the new system out-performed the other additives as it shows no reduction in conductivity experienced by proppant/fibers system. The application of this new system in the field confirmed our laboratory findings as it showed better productivity compared with the offset well treated with other additives.
Extended Matrix Acidizing Using Polymer-Acid Solutions
Authors: Amro Mohammed M. 
Published: December 2007

Abstract
The present work investigates the effect of adding polymer as a retarding agent to acid solutions to slow and control the reaction in matrix acidizing treatment of carbonate rocks. Two different polymers, Polyacrylamide (PAA) and Polysaccharide (Xanthan) and three different acids, hydrochloric acid; acetic acid and formic acid were used through this study. Polymer-acid solutions were prepared and their viscosity was measured to identify the compatibility of the acid with the polymer. The measurement was conducted as a function of shear rate, salinity, temperature and acid concentrations. The results revealed that the presence of PAA did not change the viscosity of the acid solution significantly, while the viscosity of Xanthan-acid solutions was decreased with increasing the acid concentration. Additionally, the reaction of polymer-acid solutions with the rock material was monitored under microscope. Original rock samples obtained from Saudi reservoirs containing mainly carbonate were used in the reaction. The PAA-acid solution did not show any decrease in the reaction rate compared to that of acid solution. Thus, the PAA solution applied in this study is not recommended as a retarder.
However, Xanthan-acid solutions showed a significant decrease in the reaction time. Therefore, Xanthan was selected to perform further investigations in Rotating Disk Reactor (RDR) at different pressures. The results showed clearly that the presence of Xanthan leads to an increase in the acid spending time by decreasing the reaction rate with the rock samples. This indicates that Xanthan can be added to the acid solution as a retarder to achieve an extended matrix acidizing. Moreover, scanning electronic microscopy (SEM) was conducted on pre-treated and post treated rock samples. This provides the opportunity to perform a detailed description of the rock surface and facilitates the identification of the changes occurring due to polymer-acid treatment.
Laboratory Technique for Screening Asphaltene Inhibitors for Kuwaiti Reservoirs
Authors: Oskui G. P. , Salman M. , Gholoum E. F. , Rashed A. , Matar B. S. Al , Al-Bahar M. , Kahali K. 
Published: December 2007

Abstract
Currently Kuwait Oil Company (KOC) is facing asphaltene deposition problems in the wellbore of some of the Marrat Jurassic reservoirs in West Kuwait (WK) and South East Kuwait (SEK). This has caused a reduction in production and shutting of some of the wells and a severe detrimental effect on the economics of oil recovery. This paper describes the results of the laboratory studies on the characterization and phase behavior studies of three different crude oil samples from Marrat reservoirs, and the screening of a number of commercially available inhibitors, which were proposed as a remedy and prevention of asphaltene deposition for this reservoir.
Initially the samples were characterized for their chemical and physical properties. Then the phase diagram (P-T) and Asphaltene Deposition Envelope (ADE) for bottom-hole samples were established by measuring the saturation and Asphaltene Onset Pressures (AOP) at different temperatures from reservoir to surface conditions by using the laser technique Solid Detection System (SDS). Asphaltene Flock Point (AFP) analyses were then performed by the titration technique using Stock Tank Oil (STO) samples and n- Heptane as the asphaltene precipitant. The effects of different concentrations of each inhibitor on different reservoir fluids were investigated in the laboratory, using the AFP technique. The most efficient inhibitor with the optimized concentrations for each reservoir fluid was established for economical evaluation purposes. Based on these studies, a selected inhibitor is now being used for a pilot field study.
Reducing Road Traffic Fatalities Through Driver Education: A Major Oil-Producing Company's Approach
Authors: Odunmbaku Seun , Obarewon Felix 
Published: December 2007

Abstract
Over the years, many companies in the Oil and Gas industry have taken several initiatives towards reducing the frequency of road transport accidents. Despite these efforts, accidents still occur, sometimes resulting in fatalities.
Consequently, a major oil producing company in Nigeria launched a 4-step driver training program that is hinged on eliminating major risks associated with its land transport activities. The Program identified driver education as key to reducing road traffic accidents.
Using a holistic approach, we recognized the existence of a competency gap in the driver education program in the country and focused on continuing driver education, coaching and mentoring to build the desired positive attitude in the drivers towards risk reduction in land transport activities.
Its implementation has brought a significant reduction in the frequency and severities of road traffic accident in the company within a reasonably short time. This is at a cost that is low compared to the cost of traffic fatalities.
Fracture Acidizing: History, Present State, and Future
Authors: Kalfayan Leonard J. 
Published: December 2007

Abstract
The first observation and description of hydraulic fracturing, by Grebe and Stoesser (1935), involved injecting acid to stimulate oil production from a carbonate formation. With the advent of hydraulic propped fracturing of sandstones with oil and sand in the late 1940s, fracture acidizing has been generally confined to carbonate formations; its advancement did not match that of propped fracturing. By the 1970s, propped fracturing of carbonates (in addition to sandstones) gained popularity through the greater understanding and ease of modeling fracture stimulation with non-reactive (non-acid) fluids. After the 1970s, however, advancements occurred in modeling fracture acidizing and in fracture acidizing stimulation theory. Thus, entering the 1980s and into the 1990s, fracture acidizing in carbonates increased, with development of a variety of fluid systems and multi-step procedures that are still in use today. Nevertheless, fracture acidizing continues as the less-preferred alternative to propped hydraulic fracturing in carbonates - and it has never been seriously considered as a stimulation method for sandstones.
With approximately 70% of worldwide hydrocarbon reserves in carbonate formations, and the need to simplify sandstone stimulation treatments in general, the merits of fracture acidizing and its greater possibilities - for both carbonates and sandstones - must be considered.
This paper endeavors to briefly review the historical milestones leading to fracture acidizing, and their bearing on present methods and on the imposed rules. The paper touches on the types, purposes, benefits and limitations of present technologies and methods with a focus on the propped fracturing versus fracturing acidizing decision - and with a view to future possibilities and opportunities.
Asphaltene Gravitational Gradient in a Deepwater Reservoir as Determined by Downhole Fluid Analysis
Authors: Mullins Oliver C. , Betancourt Soraya S. , Cribbs Myrt E. , Creek Jefferson L. , Dubost Francois X. , Andrews A. Ballard , Lalitha Venkataramanan 
Published: December 2007

Abstract
The fluids in large reservoirs can be in equilibrium - especially if conditions conducive to convective mixing prevail. A large vertical column of reservoir hydrocarbons offers a unique laboratory to investigate potential gravitational grading. Asphaltenes are known to exist in crude oils as a colloidal suspension, but which had not been well characterized in the laboratory until recently. In this paper, we review a gravitational gradient of asphaltenes in a reservoir and a simple theory is shown to apply. The corresponding downhole and laboratory analyses are consistent; asphaltenes exist in these crude oils in nanoaggregates. The corresponding asphaltene gradients provide a stringent and new method to test reservoir connectivity (as opposed to compartmentalization), which is key to the efficient economic development for many deepwater projects.
Productivity Increase Using the Combination of Formation Isolation Valve and Dynamic Underbalanced Perforation
Authors: Tiribelli Achille , Luca Minneci Giovanni , Daoud Ahmed , Ghodbane Fathi , Dahroug Ahmed 
Published: December 2007

Abstract
The transition from completion to production often requires the well to be killed immediately after perforation is completed, thus exposing the formation to potentially damaging kill fluid. To obtain a perforation tunnel with maximum productivity, this transition requires an optimal cleanup and the removal of the perforation damages.
A new underbalanced oriented perforating technique has been successfully implemented in Algeria. It combines the use of a formation isolation valve (FIV) to keep damaging completion fluid off the formation immediately after perforation and a perforating technique that utilizes the dynamic underbalanced method, which cleans perforations with more efficiency than conventional static underbalanced perforating method. In addition, a passive gun-orienting system was used to optimize the perforating process and enhance the well's performance.
The new technique was applied in 2003 to horizontal Well-1, which was drilled by in the Tadrart sandstone formation of the Berkine basin. After successful results in this well, the operator adopted its use in 2005 for two additional wells, Well-2 and Well-3.
The paper describes the application of the new technique to three horizontal wells of the Berkine basin and the evaluation of the related productivity increase vs. the conventional perforating method.
Wax Control by Biocatalytic Degradation in High-Paraffinic Crude Oils
Authors: Kotlar Hans Kristian , Wentzel Alexander , Throne-Holst Mimmi , Zotchev Sergey , Ellingsen Trond 
Published: December 2007

Abstract
Paraffins, mainly composed of long chain alkanes (LCA), pose a problem in the recovery of oil from fields producing paraffinic oil. This is due to the build up of paraffin deposits. Solidification and aggregation of LCA can cause serious problems in oil recovery due to the clogging of oil production pipes, deposits in the process equipments and sealing off pores in the reservoirs. Partial degradation, i.e. reduction in chain length of LCA present in such oils is likely to greatly increase its quality as well as enhance the recovery.
The approach presented in this paper is the development of biocatalytic processes involving bacteria capable of degrading LCA in situ. The project has focused on the identification of bacterial strains capable of LCA degradation and the search for and characterization of enzymes therein. One strain, identified as Acinetobacter sp. 6A2, was isolated by screening for strains capable of utilizing a paraffin with a melting point of 52-54°C. The strain was shown to be able to degrade alkanes with a chain length ranging from C10 to C40. Three enzyme systems have been identified showing overlapping alkane substrate specificities in this strain, two AlkM–type alkane hydroxylase homologues, AlkMa and AlkMb, and one system encoded by a gene given the name almA. AlkMa and AlkMb are involved in the degradation of C10 to C20 alkanes. AlmA, however, is involved in the degradation of LCA with a chain length of C30 to C40. This is confirmed in growth experiments of mutant strains. The AlmA enzyme is of particular interest as it is involved in the degradation of the more heavy wax components.
Efficiency and specificity of the enzyme systems are currently under investigation.