bluuebunny/crossref_metadata_2025 huggingface dataset:
Anguille Marine, a Deep-Sea Fan Reservoir Offshore Gabon: from Stochastic Modelling Toward History Matching.
Authors: Giudicelli C. B. , Alabert F. G. , Massonnat G. J. , Corre Bernard
Published: December 2007

The Anguille Marine field, located offshore Gabon, lies in a complex heterogeneous turbiditic formation. A geological/geostatistical approach was applied to create 3D images of the reservoir. The flow simulation of the 25 years of production history was performed after a severe upscaling from more than two millions gridblocks to 11,000 ones. The difficulties in matching the observed behaviour of the field raised several questions regarding the upscaling process, the geological model and the relationship between the two. The use of partial models helped greatly in tracking the origin of the discrepancies. The choice of the aggregation rate proved to be too important in this case of heterogeneity. It should be optimized when dealing with strongly heterogeneous stochastic models.
Waterflood-Induced Fracturing: Water Injection Above Parting Pressure at Valhall
Authors: Eltvik Petter , Skoglunn Tom , Settari Antonin
Published: December 2007

During a three year waterflood pilot program at the Valhall field, injection at a pressure higher than the Formation Parting Pressure (FFP) was employed to improve inject¡vity. Due to concerns about premature water breakthrough and reduced sweep efficiency, an engineering study was performed simulating the dynamic growth of the induced fracture. The work provided a better understanding of the dominant physical processes occurring during the Valhall waterflood pilot and gave a tool for predicting future performance.

Specialized hydraulic fracturing software, capable of modelling dynamic fracture propagation, was used. The fracturing model included the effects of 2-dimensional leak-off, fluid mobility, waterflooded region compressibility, rock and fluid thermal effects and poroelastic back stress effects. The capability of interfacing the predicted dynamic fracture to a thermal reservoir simulator was also demonstrated as a practical means of modelling water injection above FPP in single and dual reservoir descriptions.

The work concluded that minimal water breakthrough effects would occur until induced fracture lengths exeeded 20 to 40 percent (depending on reservoir media) of the interwell distance. However, with a voidage ratio of unity, the induced fracture length at Valhall will not stabilize with time due to fluid mobility effects. It was also found that the poroelastic back stress dominates over the thermal back stress in a chalk reservoir like the Valhall field.

In September 1991, water breakthrough in an offset producing well occured and the initial study has since been expanded to include matching of observed watercut performance, pulse testing and recent step rate tests. The results highlight the importance of the dynamic induced fracture as well as other factors such as pressure dependent permeability and a dual porosity reservoir description.
Fine Grid Simulation of Two-Phase Flow in Fractured Porous Media
Authors: Guzman R. E. , Aziz Khalid
Published: December 2007

Numerical reservoir simulation commonly divides naturally fractured reservoirs into matrix and fracture systems. The high permeability fractures are usually entirely responsible for flow between blocks and flow to the wells. The flow in these fractures is modeled using Darcy’s law and its extension to multiphase flow by means of relative permeabilities. The influence and measurement of fracture relative permeability for two-phase flow in fractured porous media have not been studied extensively. Transfer of fluids between the matrix and fractures is known to be one of the most important mechanisms of fluid movement in these reservoirs. Therefore, matrix/fracture fluid transfer, matrix and fracture two-phase flow, and interactions among them must be better understood for accurate simulation of oil recovery from naturally fractured reservoirs.

Experimental and numerical work on two-phase flow in fractured porous media has been initiated. The process considered is oil displacement by water in fractured porous media. Fine grid simulations of two-phase flow through a fractured core were performed in order to design the experiments and to study the effects of several key variables. These variables included fracture relative permeability, matrix/fracture capillary pressure, and matrix wettability. This paper presents the results obtained from the sensitivity analysis using fine grid simulations.

The numerical computations show that fracture relative permeabilities and wettability become important only at low capillary numbers. A dimensionless capillary number at which the fracture relative permeabilities become an important factor was estimated to be 20. The concept of a limiting capillary number may be extended to determine when fracture relative permeabilities are of influence in field scale simulations of naturally fractured reservoirs. Fracture capillary pressure was observed to have a negative effect on water imbibition, reducing the efficiency of the oil recovery. At high capillary numbers, i.e. when capillary forces are more important, water moves faster inside the matrix than in the fracture which results in high oil recovery. At lower capillary numbers, i.e. when viscous forces are more important, water channels rapidly through the fracture with a low recovery efficiency. Comparison of simulations of similar fractured and unfractured systems shows that at high capillary numbers the recovery is higher for the fractured core. At low capillary numbers the unfractured core exhibits higher recovery.
The Use of Geochemical Fingerprinting to Identify Migrated Gas at the Epps Underground Gas Storage Field
Authors: Coleman D. D.
Published: December 2007

The Epps Gas Storage Facility, operated by Trunkline Gas Company, is a converted gas field located in northeastern Louisiana. Gas was produced from what was originally defined as two different fields, Epps and South Epps, between 1928 and 1973. After depletion, the fields were converted to storage by Trunkline Gas Company and injection commenced in 1979. Between 1984 and 1987,11 production wells were drilled just to the west of the lease boundary. All of the wells were within 1/2 mile of the lease boundary, and some were only hundreds of feet away. By 1989 over 2 BCF of gas had been produced from these wells.

Geochemical fingerprinting has been used to demonstrate that a majority of the gas produced in the western area was not native gas, but was, in fact, storage gas which had migrated into the area. Plotting various chemical and isotopic parameters showed that the composition of the gas in some of the western wells had changed with time from that of native gas to that of storage gas. As a result of the geochemical, geological, and engineering studies that were carried out to verify gas migration, in 1990 the boundaries of the storage area were redefined by the Louisiana Office of Conservation to include these producing wells and thus protect the integrity of the storage project.
Simulation of a Successful Polymer Flood in the Chateaurenard Field
Authors: Takaqi Sunao , Pope G. A. , Sepehrnoori Kamy , Putz A. G. , BenDakhlia Hichem
Published: December 2007

Early results of a successful polymer project started in 1985 in the Courtenay sand of the Chateaurenard field located south of Paris, France, were presented at the fall 1988 SPE meeting. We update these data and show that subsequent performance has confirmed the highly favorable oil recovery behavior of this project. The objective of this paper is to report the results of a detailed compositional simulation study conducted to understand this favorable result. Both alternative reservoir and process characteristics were investigated in these three-dimensional simulations. In particular, both a classical layered reservoir description and a geostatistical reservoir description were investigated. The latter represents a new approach to the interpretation of polymer flooding and played an important role in our study since the attenuation of reservoir heterogeneities is known to be an important attribute of polymer flooding. We also evaluated the importance of permeability reduction and adsorption of the polymer on process performance. After obtaining a good match of the production of oil, water and polymer, we then investigated the importance of design factors on the oil recovery performance. The actual polymer flood consisted of injecting a large polymer slug followed by five smaller slugs of decreasing polymer concentration to decrease the viscosity contrast with chase water, a classical polymer flooding design method called polymer grading. We found that this grading really made very little difference in the simulated oil recovery indicating that fingering was of little importance under these conditions. This was because the oil recovery was dominated by other factors such as polymer adsorption, fractional flow, and heterogeneity. Remarkably, this appears to be the first time that a study of this type with an accurate compositional simulator has been reported for polymer flooding. The combination of better reservoir characterization methodology and accurate process simulation of polymer flooding should aid in the successful exploitation of this technology in the future. This project clearly shows the high potential of polymer flooding under the appropriate reservoir conditions and with good design and implementation methods.
Mobility of Hydrocarbon Liquids in Gas Condensate Reservoirs: Interpretation of Depletion Laboratory Experiments
Authors: Morel D. C. , Lomer J-F. , Morineau Y. M. , Putz A. G.
Published: December 2007

When a rich gas field is put into production, one has to decide on a production mechanism which may involve either depletion, or partial or full pressure maintenance through gas or water injection. In order to reach a decision, it is essential to know not only the thermodynamics of the condensates but also the laws of their migration through the porous medium. This is achieved by a thermodynamic study, measurements of interfacial tensions between separate phases and by running a depletion experiment in bottom hole conditions. The interpretation of the set of measurements provides the necessary tools to run field scale simulations.

We present the study of the fluid behaviour of one of our newly discovered fields, the results of which were integrated in a full field study to define the scenarios of possible field production schemes.

The thermodynamic behaviour of the rich gas was represented by a Peng-Robinson equation of state involving seven pseudo components. The computed interfacial tensions between phases in equilibrium at different pressures ranged between .05 dyne/cm and 3 dyne/cm, they were very close to actual laboratory measurements. A depletion experiment was performed on a reconstituted 2 meters long core in bottom hole conditions (141°C, 400 bars initial pressure), the pressure was decreased very slowly, at less than 1 bar/day, and several stops were imposed to observe pure gravity drainage. Only a small fraction of the condensates was produced but the liquid breakthrough was observed very early during the depletion. The experiment was history matched with a compositional model, relative permeabilities for gravity drainage were deduced. It was necessary to introduce a dependence of the relative permeabilities on interfacial tensions below a threshold value of .15 dyne/cm.
Design and Performance of a Horizontal Well Waterflood Project in New Hope Shallow Unit, Franklin County, Texas
Authors: Huang W-S. , Kaetzer T. R. , Bowlin K. R.
Published: December 2007

In 1991, a pair of horizontal wells were drilled in the Pittsburg "C" sandstone reservoir of the New Hope Shallow Unit (NHSU) in East Texas. The first well was a 1500-ft horizontal oil well and the second was a 1500-ft water injection well.

The NHSU Pittsburg formation is a relatively tight sandstone reservoir undergoing a waterflood project expansion. It has a 45-year production history and is located at a depth of about 8000 feet. A single well model was used to predict horizontal well production potential and compare a horizontal development to a conventional vertical well development. After the initial evaluation appeared favorable, a fieldwide simulation study, including a 45-year history match and a horizontal well production forecast with and without a horizontal injection well, was made to further assess the project. Different scenarios were examined to determine the optimum development program. The wells were drilled in the last quarter of 1991. Actual production results appear to be tracking the forecast rates.

This paper summarizes the reservoir engineering studies performed as well as the planning, drilling and completion of these wells. Production histories as well as problems and their solutions to date are also documented. The application of horizontal wells in sandstone reservoirs demonstrates that new life can be brought to mature oil fields.
An Effective Matrix Stimulation Technique for Horizontal Wells
Authors: Tambini Mauro
Published: December 2007

This paper presents and discusses guidelines for matrix stimulation design, real-time control and post treatment evaluation on the basis of field results obtained from eight (8) horizontal and four (4) drain hole wells. A stimulation technique originally developed for vertical wells1, has been successfully modified and applied to horizontal wells. An optimized treatment procedure consists of placing the acid mixture downhole through coiled tubing and bullheading "ad hoc" volume of treating fluid at maximum bottom-hole pressure differential and rate. Equations to link measurable injection parameters (pressure and rate) with evolving skin effect are presented. In order to evaluate the effectiveness of the stimulation treatment, several Production Logs were run downhole using a coiled-tubing-conveyed wireline system. These revealed a remarkable distinct relationship between the producing horizontal length and the injection rate. A stimulation rate as high as 52 bbl/min (pumped in matrix, without fracturing, conditions) allowed almost total (95%) horizontal length contribution to the overall production. Without the use of diverting the technique was applied effectively to long horizontal production intervals (proven up to 1500 ft max).

The most effective results from this stimulation technique are obtained when dealing with reasonably homogeneous primary permeability reservoirs. For macrofractured formations (which are generally excellent candidates for horizontal wells) mechanical isolation plus the present technique is a more successful stimulation method to adequately cover the entire production interval.

Case histories are also described. A case of a stimulation repeated in the same well using different procedures is reported, as well as features of Production Logging Tools used in the field.
A Knowledge-Based Approach to Problem Identification in Producing Wells
Authors: Cosenza Giacomo , Tambini Mauro , Paccaloni Giovanni
Published: December 2007

This paper presents a knowledge-based system (KBS) for the identification of problems in producing wells. The KBS is based on a general Well Problems Analysis (WPA) methodology that entails three main activities: verification of a problem's existence, identification of a preliminary set of possible problems, refinement of the most plausible problem(s). The relevant experts’ knowledge has been formalized by means of a classification approach based on the organization of all problems in a hierarchy of classes and, by associating the corresponding symptomatology with them. The system, validated at the company headquarters, is currently in use in the operating districts.

The system is a part of a more comprehensive project, called PROGRESS (PRoduction Optimization inteGRated Expert SystemS), aimed at providing a decision support system for well production optimization.
A Stochastic Fault Modeling Procedure Applied to a North Sea Reservoir
Authors: Selvig Arild , Fristad Torbjørn , Silseth J. K. , Madsen Rune
Published: December 2007

In reservoirs with limited or poor seismic resolution, faults with throws below the seismic resolution can often act as flow-restricting barriers. Hence, the uncertainty related to the small-scale fault pattern may have significant impact on the precision of the production profile predictions and recovery estimates.

This paper discusses the impact of undetectable, small faults on the field production performance. A consistent methodology for incorporating the combined effect of uncertainty in the geometric fault pattern and uncertainty in the fault transmissibilities is presented. The subseismic faults are assigned to the numerical grid through a stochastic approach where fault densities, fault dimensions, and fault throw distributions are specified. In addition to the juxtaposition of the model layers at the various fault locations, alteration of flow potential across the faults (caused by for example mechanical or chemical sealing), is introduced as stochastic fault transmissibility multipliers.

An example, based on data from a highly overpressured North Sea reservoir which has been evaluated for a possible field development, is presented to illustrate the usefulness and flexibility of the proposed stochastic fault modeling procedure.
Extensional vs. Shear Fractures: Implications for Reservoir Characterisation
Authors: Loosveld R. J. H. , Franssen R. C. M. W.
Published: December 2007

Fractured reservoirs are typically strongly anisotropic and heterogeneous, irrespective of whether the fractures are extensional or shearing-induced. Fracture network data are notoriously hard to obtain. Here, we present new results on fracture-network characteristics from outcrop and experimental studies.

In contrast to current views that fault and fracture patterns are of a fractal nature, these results demonstrate that extensional fractures (joints) are non-fractal. Shear fractures and faults, on the other hand, were found to agree with fractal concepts on a wide range of scales. They form scale-invariant patterns. Both fracture networks consisting of shear fractures and those consisting of joints have a high degree of fracture connectivity.

Extensional fractures tend to link with fractures of the same family and to abut against pre-existing joints. Blunting of joint tips at intersections also improves the connectivity of the fracture network. Monte Carlo simulation techniques have been used to determine the effective permeability of networks of extensional fractures. An outcrop-derived model yielded a markedly anisotropic bed-parallel permeability.

Localised shear failure in porous sandstones occurs by particulate flow or, more frequently, by cataclasis. Particulate flow leads to significant permeability increase whereas cataclasis may result in permeability increase or decrease, the latter being more common. Shear fractures are characterised by zones of anastomosing cataclastic deformation bands with enclosed lenses of undeformed matrix material. Thus, there will be no tortuous flow paths through these lenses around the tips of isolated deformation bands across the shear zone. Reservoir compartmentalisation may result from deformation bands which will have, at best, very subtle seismic expression.
On the Transport Properties of a Rod-Type Polymer in Sand Packs
Authors: van Domselaar H. R. , Fortmüller Claudia
Published: December 2007

Determination of rheological parameters of rod-type bio-polymer (Xanthan) solutions as a single (mobile) phase in sand packs is discussed. In one series residual oil is present.

Apparent viscosities approximated from sand pack experiments could be described by a Carreau type of equation. Since no real in situ polymer solution viscosities and permeabilities to these solutions can be determined up to now a practical way out of this problem is the determination of mobilities to the polymer solution with the help of the Darcy equation. These polymer mobilities can be described with a modified Carreau type of equation.

RF, RRF values and polymer mobilities are discussed in the context of apparent polymer viscosities.

Up-front and residual polymer retention have been estimated for conditions of 100 % accessible porevolume.
Pilot Testing of Membrane Technology to Selectively Remove Sulfate Ion from Seawater in the Wilmington Field
Authors: Scott J. A.
Published: December 2007

Secondary recovery processes using highsulfate ion water sources can lead to reservoir souring. The waterflood operations for the Long Beach Unit of the East Wilmington Field are located in a highly urban and environmentally sensitive location in the Long Beach Harbor, California. One of the Unit's goals is to prevent reservoir souring. In addition, the formation water contains significant amounts of barium ion. Injection of highsulfate water sources results in barium sulfate precipitation and scaling of downhole pumps.

Pilot testing was conducted on membrane technology designed to selectively remove sulfate ion from open-ocean sea water. The pilot operation was installed on Island White of the Long Beach Unit. The process was evaluated to assess technical feasibility, characterize product water for reservoir compatibility, and compile operating data. Laboratory coreflooding experiments were conducted with the product water to evaluate reservoir compatibility because many of the producing zones are damage-prone.
The Impairment of Scale Inhibitor Function by Commonly Used Organic Anions
Authors: Barthorpe R. T.
Published: December 2007

Trace amounts of metal chelant additives, commonly used in stimulation and fracture fluids, have been shown to have a debilitating effect upon the performance of widely used barium sulfate scale inhibitors. EDTA and citric and gluconic acids render examples of some commonly used scale inhibitors (phosphonates, polycarboxylates and phosphate esters) completely ineffective at concentrations as low as 0.1 mg/L. Such low concentrations may be expected to return from formation stimulation treatments for many months and would appear to jeopardize any scale inhibitor program in place. The testing was based upon a simulated North Sea scaling system at pH 4.0 and 6.0. Scale inhibitor concentrations studied were 50 and 100 mg/L The large negative effect of the organic chelants was observed at pH 4.0 and 6.0. The only scale inhibitors studied which remained ambivalent to these interferences were large polymeric vinylsulfonates.
Removal of Mineral Scale from Reservoir Core by Scale Dissolver
Authors: Rhudy J. S.
Published: December 2007

The effectiveness of commercially available scale dissolvers for removing mineral scales from reservoir cores was studied in the laboratory. Fluids and preserved cores from a major North Sea reservoir were used. Equipment and procedures were developed to reproducibly deposit scale in reservoir cores. Then, the effectiveness of aminopolycarboxylic acid for removing scale from the cores was investigated. Deposition and dissolution of mineral scales were monitored by measurement of oil/water mobility in the core, effluent scale cation concentrations and scanning electron microscope observation. Mineral scales studied included calcite, barite and mixed scales.
The Modelling of Adsorption and Precipitation Scale Inhibitor Squeeze Treatments in North Sea Fields
Authors: Yuan Ming Dong , Sorbie K. S. , Todd A. C. , Atkinson L. M. , Riley Helen , Gurden Stuart
Published: December 2007

This paper presents an analyste and design study of field scale inhibitor squeeze treatments. Simulators of varying levels of complexity have been used to model squeeze data from several wells in North Sea fields. The modelling has been carried out both for simple single sandbody squeezes and for inhibitor treatments in heterogeneous systems where there is free crossflow between strata. The appropriately matched results are then used in the design of improved inhibitor squeeze strategies for the fields studied.

The main results from this study relate to the field design criteria which should be applied to both adsorption/desorption and "precipitation" scale inhibitor squeeze treatments. Using quite simple models to simulate the field results, a wide range of sensitivities in adsorption/desorption squeeze treatments has been investigated (e.g. injection concentration, overflush size, shut-in time etc). A more complex model was used to simulate an adsorption squeeze carried out in a multi-layer, near-well formation. Results show the significant effect of reservoir heterogeneity on inhibitor returns and, for such cases, that the placement strategy for inhibitor slug injection should be taken into consideration. A field "precipitation" squeeze has also been modelled which highlights the effect of local formation temperature. The results demonstrate the importance of selecting appropriate preflush and overflush volumes for creating the correct thermal conditions for in-situ inhibitor "precipitation".

A number of generally applicable conclusions arise from our study and some example economic results are presented. In particular, for precipitation type processes, some field application guidelines are given for the first time in the literature.
A New and Reliable Model for Predicting Oilfield Scale Formation
Authors: Yeboah Y. D. , Somuah S. K. , Saeed M. R.
Published: December 2007

A new and reliable Oilfield Scale Prediction Model (OSPMod) has been developed and is presented. Unlike the available models which predict only scaling potential using thermodynamics and limited solubility data, OSPMod predicts the potential and deposition profile based on extensive thermodynamic and kinetic data. The model uses experimental solubility data in NaCl, MgCl2, CaCl2, and their mixtures, and in natural oilfield brines to determine the saturation index. Critical saturation indices beyond which scaling occurs have been established for the common oilfield scales (BaSO4, SrSO4, CaSO4 nH2O, and CaCO3). The model uses the flow characteristics and experimental kinetic data to predict the scale deposition profile from the bottomhole to the surface, once the critical saturation index is exceeded. The model has been developed as a menu-driven, user-friendly software. It is applicable to all the common oilfield scales and provides several input, computation and output options. Graphic presentation of results is a useful feature of OSPMod. The accuracy, reliability, and key features of the model are illustrated in the text with oilfield and test well cases.
Studies of the Effects of Xanthan on the Phase Behavior of Single-Component Surfactant/Reservoir Oil/Brine Systems Using PVT Measurements
Authors: Veggeland Kirsti , Hodne Helge , Avstad Tor
Published: December 2007

Co-injection of a low concentration surfactant and polymer solution, termed Low Tension Polymer Flood (LTPF), has been suggested to improve the efficiency of chemical flooding. The multiphase behavior of a live crude oil from the North Sea containing a single-component anionic surfactant, n-C12-o-xylene sulfonate and NaCl brine, has been studied at different temperatures and pressures with and without the presence of biopolymer. Both systems showed the usual types of phase behavior, i. e., a lower microemulsion, a middle phase microemulsion, and an upper microemulsion termed II(-), III and II(+) respectively. No optimal pressure or temperature was observed by conducting pressure and temperature scans. The solubilization parameter of water is always higher than the solubilization parameter of the oil, S(w)>S(o).

The effect of temperature on the phase behavior is complicated. Equilibrium between two microemulsion phases at temperatures close to the critical temperature for phase transitions, is suggested. The system moved into the II(+) state without reaching optimal conditions for oil recovery as the temperature is increased. The phase behavior is discussed in terms of the oil composition.

The addition of xanthan resulted in an increasing ratio S(w)/S(o) and the system is moved toward the II(-) state. The pressure for the phase transition III/II(-) is lowered, while the pressure for the phase transition II(+)/III is nearly unaffected.
Effect of Surfactants on Hydrate Formation Kinetics
Authors: Kalogerakis Nicolas , Jamaluddin A. K. M. , Dholabhai P. D. , Bishnoi P. R.
Published: December 2007

In this paper we investigate experimentally the effect of surfactants on the formation kinetics of methane hydrate. The compounds tested include: anionic, cationic and nonionic surfactants. Experimental results indicate that surfactants (at concentrations levels near their CMC) do not influence the thermodynamics, however, they have a strong influence on the kinetics of gas dissolution in the water phase as well as on the overall rate of hydrate formation. In addition, the formed hydrate particles in the presence of the various surfactants exhibit diverse agglomeration characteristics. This work is part of an overall effort to develop the technology required for the safe operation of offshore oil and gas transportation pipelines without inhibitors.
Improved Gas Chromatographic Analysis of Reservoir Gas and Condensate Samples
Authors: Kriel W. A. , Spence A. P. , Kolodziej E. J. , Hoolahan S. P.
Published: December 2007

A methodology is provided for analyzing high temperature and high pressure reservoir fluid samples directly on a gas Chromatograph. Coupled with a procedure for concentrating the heavy end fraction of lean gases, the methodology is extended to samples containing as little as 1 wt % C6+. Analysis of example fluids demonstrates relative precision and accuracy of 97% for most components when present in significant concentrations. For lean gases, errors of ±10% are demonstrated for heavy end components of samples with 2–8 wt % C6+. The methodology has been successfully applied in estimation of condensate reserves and gas cycling studies.
Establish Chemical Treatment and Management System for Oil Production and Water Injection Facilities in the North Sea
Authors: Georgie W. J. , Bryne K. H.
Published: December 2007

With potential increase in water injection requirement, increase in oil production rate and the unavoidable increase in water production, an improvement in the chemical treatment programmes was deemed to be necessary in the mid eighties. As a result, an assessment of the chemical treatment programmes philosophy was carried out in the Statfjord field. The assessment programme philosophy covered different aspects of all chemicals used for the water injection systems, process systems as well as utility process related facilities, such as, ballast water systems, heating and cooling systems and fire water systems on the three Statfjord platforms. The assessment programme was intended to improve the methods used for selecting chemicals for the different systems and improve the application and the daily follow up of the chemicals offshore. Consequently, a better control on the consumption of the chemicals in the field can be achieved, as well as reduce the environmental impact and risk of the use and discharge of production chemicals in the North Sea.

The objectives were achieved by adapting a systematic approach in the selection and application of chemicals. The issues covered in these objectives included: Clearer definition of individual problems in the systemsSelect suitable simplified methods for testing new chemicals, either onshore or offshoreSystem parameters optimisation included in the testing programme for chemicalsChemicals characteristics and partitioning in the individual systemsThe toxicity of chemicals and biodegradabilityThe handling aspects of chemicals by offshore personnelImprovements and upgrading of the chemical injection facilitiesEstablish operation procedures in order to implement and follow up the required treatmentsImprove the chemical injection facilities on the platforms

In addition, a training programme was introduced for operation personnel, in order to improve the level of knowledge as well as understanding of chemical treatment requirements, and the importance of these programmes in maintaining stable operation and in reducing fluid handling related problems.

Having completed the assessment and the implementation of the new chemical treatment programme philosophy by the late eighties, a new chemical treatment and management system was established on Statfjord platforms. The outcome of such an approach was, more effective treatment, as well as reduced cost and quantity of chemicals used per volume of oil produced, treated produced water and treated injected water.

With the increased environmental awareness, the new procedures gave a better and an instantaneous view on the level of used and discharged chemicals. Such data are required for regular reporting to the environmental authorities.

The experience gained over the past few years has been also used in improving the design of the required chemical injection facilities on newly developed platforms, as well as chemical treatment programmes on newly developed fields.
Rheological Characteristics of Reticulated Bacterial Cellulose as a Performance Additive to Fracturing and Drilling Fluids
Authors: Westland J. A. , Lenk D. A. , Penny G. S.
Published: December 2007

Working since 1983 Weyerhaeuser through biotechnology research has developed a new form of cellulose with an intertwined reticulated structure. This cellulose, produced from bacteria, has unique properties and functionalities unlike other conventional celluloses. When added to aqueous systems, the Reticulated Bacterial Cellulose (RBC) dramatically improves fluid rheology and particle suspension over a wide range of conditions. Extensive laboratory and pilot equipment testing has been done using RBC as an additive to a variety of fracture fluids and to a limited extent, drilling fluids. The test results show advantages in fluid performance and significant economic benefits by the addition of RBC.
Delayed Crosslink Fracturing Fluid Rheology Influenced by Thermal and Shear History
Authors: Lord D. L. , Yaritz J. G.
Published: December 2007

Using a Model 50 Fann viscometer, the viscous behavior of a delayed-crosslink fracturing fluid was evaluated after the fluid was subjected to various combinations of thermal and shear history. Fluid thermal and shear histories were created by pumping a mixture of polymer solution and crosslinking additive through tubing coils situated in a series of thermally-controlled baths. Specifications of the preconditioning device are provided in the paper. By varying bath temperatures and flow rates through the preconditioning coils, it was possible to create a wide variety of fluid thermal and shear histories. An organo-metallic crosslinking agent was continuously mixed into the polymer solution as it was being injected into the preconditioning device. At the point where the chemically reacting mixture exited the preshear device, it was routed, without stopping, into a rotating viscometer cup by means of a quick-connect. In this manner, the fluid sample captured within the viscometer cup experienced a continuous shearing action similar to that experienced in the field environment. Sample rheology was then monitored over a 2-hour period at elevated temperature using a R1 B5 X measurement configuration. The merits of using the R1 B5 X rather than the wide gap R1 B2X measurement configuration are discussed. Rheology results from nine uniquely different thermal-shear history combinations were compared to determine the relative influence of each parameter on the final fluid viscosity.
The Investigation of the Corrosion Inhibition Mechanism Utilizing AB Initio Quantum Mechanical Calculations
Authors: Simpson C. Q. , Gdanski R. D.
Published: December 2007

To understand the fundamental principles that control the corrosion inhibition mechanism, ab initio quantum-mechanical calculations have been performed on three corrosion inhibitors and their reaction products resulting from hydrogen atom attack. The results of these calculations and electron population analysis are correlated with experimental corrosion-test data. Based on this correlated data, a reaction for the inhibition mechanism is suggested, factors controlling inhibition effectiveness are determined, and recommendations are made for improved corrosion inhibitors.
NMR Imaging of Gelation Processes Inside Rock Cores
Authors: Maddinelli Giuseppe , Carati Claudio , Brancolini Alberto , Rossi Elio , Causin Emilio
Published: December 2007

Although permeability modifications of oil reservoirs by means of in-situ gelation processes are of great interest in additional oil recovery, little information on the phenomena taking place inside the porous media during gelation is available.

A new approach based on Nuclear Magnetic Resonance Imaging (MRI), a novel non-destructive technique, has been tested. The NMR method is compared with classic laboratory tests based on rheology and pressure drop measurements. The results of several laboratory experiments carried out at different conditions, in vitro and inside porous media, are presented. NMR imaging constitutes a powerful tool to characterize the gelling process inside the porous media complementary to the classical displacement tests (i.e. pressure drop).
Effective Gelation-Delaying Additives for Cr+3/Polymer Gels
Authors: Albonico Paola , Burrafato Giovanni , Lullo Alberto Di , Lockhart T. P.
Published: December 2007

A coordination chemical approach for delaying the gelation of Cr+3/polymer compositions has been explored. By screening organic ligands for their gelation delaying power with hydrated Cr+3/polymer and Cr(OAc)3/polymer solutions several powerful retarding ligands have been identified. Use of the pre-formed Cr+3 complexes of these ligands together with additional, uncomplexed ligand in the gelant solution provides outstanding control over the gelation time over the temperature range 60°-135°C. With these compositions gelation times spanning the range from several hours to one month or more have been obtained at temperatures up to 120°C; such gelation delays should be suitable for a number of near-well and in-depth gel treatments. In virtue of the low toxicity of Cr+3 and its complexes, the potential environmental impact of the new gelation compositions is notably reduced relative to those employing Cr+6 or formaldehyde. A number of variables have been evaluated for their influence on the gelation delay, and preliminary experimental results on the propagation of Cr+3 in porous media at high temperature are reported. Our current mechanistic understanding of the gelation delay chemistry is also described.
A Synergistic Approach to the Development of the Dulang Field, Offshore Peninsular Malaysia
Authors: Egbogah E. O. , Chandramohan S. , Embong M. K.
Published: December 2007

This paper describes the evolution of a synergistic approach to the successful development of the Dulang Field, Offshore Peninsular Malaysia. The key factors that have contributed to the success of the approach include careful planning, systems-based execution, integration of multidisciplinary technical expertise and effective team approach to field development and reservoir management Team members consisting of geologists, geophysicists, drilling engineers, petrophysicists, reservoir engineers, petroleum technologists and facilities/project engineers convinced management early in the project life that a sound, integrated reservoir management plan was critical for maximizing the value of oil and gas reserves from discovery through abandonment of the Dulang field.

The staged development of this complex field with two of the planned four platforms currently onstream entails the application of reservoir management strategies for up to fifty separate depletion plans for identified reservoir units. It is an innovative approach to offshore development, involving management commitment and synergism of disciplines that has placed a premium on flexibility in approach. The development of the field has been justified by the large reserves potential. The original hydrocarbons-in-place include about 685 MMSTB of oil and 495 BSCF of gas. Optimized depletion strategy developed through geological reservoir description and reservoir studies have formed the basis for the staged development now in use in the Dulang field.

The synergistic approach being reported here has been facilitated by the availability of integrated data storage and interactive technologies within PETRONAS Carigali Sdn Bhd (Carigali). These systems have provided interactive working environment amongst team members and it shall continue to serve as the basis for further development and management of the Dulang field.
New Emphasis in Engineering Schools on Graduate Education
Authors: Staley Thomas F. , Thomas Gordon W. , Brown Kermit E.
Published: December 2007

In 1957 the first Sputnik was launched into space. A crash program was started to increase our technical know-how. In particular, the universities of our nation were called upon to produce more and more qualified engineers and produce more and more qualified engineers and scientists. A new emphasis was placed on graduate research at the M.S. and Ph.D. levels. More research funds were made available from both government and industry. Competitive bargaining for top graduate students now exists between universities and the good students themselves realize that they are at a premium.

Has university research moved from its position to seek out new knowledge and to serve position to seek out new knowledge and to serve in its proper perspective as a part of the teaching process or is research now being conducted as an end in itself? Have undergraduate curricula been neglected to the extent that the graduate program itself is in jeopardy?

Some universities have chosen to place most of their emphasis on graduate research. Many professors have made a status symbol of a light professors have made a status symbol of a light teaching load to the extent that they measure their prestige by the infrequency of their contact hours with students.

The University of Tulsa offers both an M.S. and Ph.D. in Engineering. However, our feeling is that we must maintain and continue to emphasize the undergraduate programs. An Honor's Program was initiated in Petroleum Engineering Program was initiated in Petroleum Engineering in 1966. Effective September, 1969, an average of 100 students in Petroleum Engineering will be receiving Honor's scholarships. This assures a high quality undergraduate program since these young men must maintain a "B" average or better. These programs have now been initiated in the entire College of Engineering and Physical Sciences as well as an over-all University Scholarship Program.

An outstanding university must have both superior teaching and research. A strong graduate research program is necessary since this is the way in which the ideal college professor maintains his competence and enthusiasm in his area of specialization. However, we must not lose sight of the fact that our main objective is the promotion of learning and inquiry for students and faculty alike.
Samarang K5/7 Reservoir Simulation Study
Authors: Lee Boo-Soon
Published: December 2007

A 3-dimensional, 3-phase reservoir Simulation model was constructed using a black oil reservoir Simulator to understand the complex reservoir fluid dynamics, and its effects on ultimate oil recovery. The paper describes the various phases of the model study, which entails the construction of the reservoir model, matching of the historical well performance and optimising reservoir Operation strategy through prediction of future reservoir performance under various operating scenarios. The flndings of the study were used to formulate a cost-effective reservoir management strategy and further development plan to maximize hydrocarbon recovery.
Continuing Education Program - Los Angeles Basin
Authors: Fazio Patrick J. , Donnelly William L. , MacLean M.A.
Published: December 2007

The Los Angeles Basin Section Continuing Education Program was the first in the SPE and is typical of SPE efforts around the country. Initial membership interest was high, but recent classes have been only partially filled. Other SPE Sections have had partially filled. Other SPE Sections have had similar experiences. This lack of participation is the result of lack of motivation participation is the result of lack of motivation and should be of great concern to the industry. Primary responsibility for maintaining technical competence rests with the individual; however, companies share this responsibility. In the opinion of the authors, most oil companies have been permissive but not energetic in their support of the SPE Program. A number of techniques industry can use to motivate their employees toward continuing education are presented and discussed.

Introduction

Unlimited opportunity exists for the engineer in today's technically snowballing society to expand his capabilities and contributions. The degree to which he should pursue continuing education is commonly pursue continuing education is commonly debated in connection with the age-old controversy of experience versus academic achievement. Oil companies go to great expense to improve their technical staffs and even recruiting practices are influenced by where key company personnel stand in this "great debate." One thing is certain, the employee will be more valuable if he updates himself in matters which pertain to his area of endeavor.

In February, 1965, the Los Angeles Basin Section kicked off the SPE Continuing Education Program. The objective of this program has been to provide a means of raising the general level of technical competence in the petroleum industry. Thirty-one Sections now offer some form of continuing education to 85% of the SPE total membership; however, the Los Angeles Basin Section Program which is typical of others in the SPE has attracted only about 15% of its membership. Apparently, you can lead the engineer to education, but you can't make him learn.

In this paper, the authors who are members of the Los Angeles Basin Section Continuing Education Committee, discuss the reasons for the declining participation. Techniques are recommended for the motivation of the hard-core, inactive member.
Well Testing for Gas Condensate Reservoirs
Authors: Thompson L. G. , Niu Jin-Guo , Reynolds A. C.
Published: December 2007

The analysis of well-testing pressure data obtained at a well producing a gas condensate reservoir is considered. It is assumed that a liquid bank forms in the vicinity of the well. Only radial flow problems are considered; thus, our objective is to find semilog analysis procedures that can be applied to our two-phase flow problem.

The contributions and results of this research work can be summarized as follows: (i) We present theoretical results for drawdown and buildup semilog analysis equations based on the single-phase real gas pseudopressure of Al-Hussainy. (ii) A theoretical equation for the apparent skin factor observed during buildup is derived. The apparent skin factor is a linear combination of the mechanical skin factor and a pseudoskin factor due to the existence of a two-phase Zone near the wellbore. The value of the pseudoskin factor depends on the size of the liquid bank and the near-wellbore value of effective gas permeability with the two-phase Zone, (iii) It is shown that by combining results of drawdown and buildup analysis or by analyzing buildup data from a a modified isochronal test, we can separate the components of the skin factor, i.e., to determine the mechanical skin factor, the radial extent of the liquid zone and the average effective gas permeability within the liquid zone. The determination of the individual components is based on the theoretical equation for the buildup apparent skin factor.