bluuebunny/crossref_metadata_2025_split huggingface dataset:
Next-Generation Modeling of a Middle Eastern Multireservoir Complex
Authors: Al-Matar Bader S. , Pathak Ashok , Mandal Dipak , Killough John , Fleming Graham , Engle Colin , Brock Nigel , Varma Sanjeev 
Published: December 2007

Abstract
An elusive goal of reservoir simulation has been the ability to accurately model multiple reservoirs producing through a common surface facility. In the past, loosely coupled techniques have often been used which did not fully converge the overall solution of the simulation. This led to instabilities at worst or to inaccuracies in the solution at best because it did not properly account for the complete interaction of the reservoir. In the following paper, we discuss the application of a fully implicit, tightly coupled surface-subsurface simulation with a next-generation reservoir simulation of the north Kuwait Raudhatain multireservoir complex with common surface facilities using actual field data. In addition to surface-subsurface simulation, the reservoir simulator provides a parallel unstructured grid capability and significant computational efficiency from a improved model formulation. For the simulations of this study, four stacked reservoir horizons form the subsurface portion of the model. The surface facilities consist of the production gathering centers, and gas lift and water injection capabilities. A unique feature of the model included the capability to automatically switch the flow lines for the more than 500 wells among six different separator trains at a gathering center, depending on the wellhead pressures and producing water cuts. The resultant 600,000 cell multireservoir model was first validated by comparing fifty years of historical performance for the individual reservoirs from the original simulation models with the next-generation model. In general, the matches between the original simulations and those generated with the next generation simulator were extremely close for each of the four reservoirs. With the validation completed, a simulation surface network was constructed that attempted to capture all of the salient features of the current and future surface facilities for the field by including, for example, actual flowline lengths in the model. In particular, future facilities expansions were included with gas lift, water injection, and the multiple header switching of wells at the gathering center. The complete model, including all four reservoirs and the surface facilities, was run for a prediction period of over sixty years. The resulting predictions provided, for the first time, solutions that show the interaction of the reservoirs with the surface facilities, including reallocation of production and injection based on facilities constraints. The multireservoir model forms the basis of a field planning and optimization tool whose forecasts can be used with greater confidence because of the inclusion of the comprehensive physics of the field production. A comparison of the simulation output with a spreadsheet field planning model shows interesting results which should form the basis of future work.
Biosurfactants Produced From Agriculture Process Waste Streams To Improve Oil Recovery in Fractured Carbonate Reservoirs
Authors: Johnson S. J. , Salehi M. , Eisert K. E. , Liang J. -T. , Bala G. , Fox S. L. 
Published: December 2007

Abstract
We examined the ability of surfactin, an anionic lipopeptide surfactant produced by Bacillus subtilis, to mediate wettability changes that positively affect oil recovery in fractured carbonate rock. On both a weight for weight and a molar basis, surfactin has a greater ability to alter a carbonate rock to a more water-wet state than does sodium laureth sulfate (SLS). Surfactin, was produced by growing Bacillus subtilis on high-starch medium to represent agricultural effluent, and a suitable benchmark chemical surfactant was selected for comparative study. Cores and crushed samples of Lansing-Kansas City (LKC) carbonate reservoir material were cleaned and characterized. Crushed rock was aged in crude oil to ensure that it was strongly oil-wet and rapid wettability tests were performed to assess the wettability change mediated by low concentrations of surfactin and SLS. Static adsorption of surfactants on LKC rock was assessed and dynamic adsorption in intact cores was measured. Surfactin exhibits higher specific adsorption onto crushed LKC.
A Rapid and Robust Method To Replace Rachford-Rice in Flash Calculations
Authors: Li Yinghui , Johns Russell T. 
Published: December 2007

Abstract
Rachford-Rice iterations are widely used in equation-of-state (EOS) flash calculations to determine phase equilibrium compositions from constant equilibrium ratios (K-values). The method, however, can be slow to converge and in some cases may not converge at all.
This paper presents a simpler and more robust method to replace Rachford-Rice and similar methods in flash calculations. The new objective function has two fewer asymptotes compared to Rachford-Rice and is based on one of the equilibrium phase mole fractions, typically the lightest component.
Results with the new objective function demonstrate that rapid convergence using Newton-Raphson iterations (NR) is assured because the correct solution is determined within a small range (window). In that window, no poles exist no matter the overall composition and the objective function is often linear. Improved linearity of the objective function contributes to increased convergence speed even near critical points. The method can be easily incorporated into any compositional simulator without significant modifications.
Effect of Temperature on Degradation of Polymer Drag Reduction and Heat Transfer in Non-Newtonian Fluid
Authors: Hamouda A. A. , Moshood Omotayo. T. 
Published: December 2007

Abstract
Drag reduction is a well known phenomenon. Possible mechanism deduced from heat transfer has been suggested earlier for non isothermal Newtonian fluid treated with polymer drag reducer. Several works have shown the susceptibility of the long chain polymer to shear degradation, hence reduction in its performance. Most of the works were performed in isothermal conditions. Moreover, it mostly covers water soluble polymers. There is an increasing need to address the shear degradation phenomenon for oil soluble polymer, where its performance is related to increase transportation capacity of pipeline as well as energy savings.
In this work the degradation of oil drag reducing polymer in a non-isothermal environment in which rheological change of oil (the carrier fluid in this work) occurs as the fluid is transformed from Newtonian to non-Newtonian is addressed. In another words, the paper addresses the temperature effect on the degradation of the oil soluble drag reducer polymer in a wide range of temperatures. The non-Newtonian fluid behaviour here is defined as the temperature below which paraffin deposits in presence of drag reducer polymer. The validity of equations for estimating Colburn factor is also addressed.
An Ensemble Level Upscaling Approach for Efficient Estimation of Fine-Scale Production Statistics Using Coarse-Scale Simulations
Authors: Chen Yuguang , Durlofsky Louis J. 
Published: December 2007

Abstract
Upscaling is often needed in reservoir simulation to coarsen highly detailed geological descriptions. Most existing upscaling procedures aim to reproduce fine-scale results for a particular geological model (realization). In this work we develop and test a new approach, ensemble level upscaling, for efficiently generating upscaled two-phase flow parameters (e.g., upscaled relative permeabilities) for multiple geological realizations. For this purpose, flow-based upscaling calculations are combined with a statistical estimation procedure (cluster analysis). This approach allows us to numerically compute the upscaled two-phase flow functions for only a small portion of the coarse blocks. For the majority of blocks, these functions are estimated statistically based on single-phase velocity information (attributes), determined when the upscaled single-phase parameters are calculated. The procedure is designed to maintain close correspondence between the cumulative distribution functions for the numerically computed and statistically estimated two-phase flow functions. We apply the method to two-dimensional synthetic models of multiple realizations for uncertainty quantification. Models with different geological heterogeneity and fluid mobility ratios are considered. It is shown that the method consistently corrects the biases evident in primitive coarse-scale predictions and can capture the ensemble statistics (e.g., P50, P10, P90) of the fine-scale results almost as accurately as the full flow-based upscaling procedures, but with much less computational effort. The overall approach is flexible and can be used with any combination of upscaling procedures.
Flexible Treatment Program for Controlling H2S in FPSO Produced-Water Tanks
Authors: Burger E. D. , Andrade C. A. , Rebelo M. , Ribeiro R. 
Published: December 2007

Abstract
Tanks used to store produced water on Floating, Production, Storage and Offloading units (FPSOs) are extremely susceptible for generation of high hydrogen sulfide (H2S) levels due to the activity of sulfate-reducing bacteria (SRB). The FPSOs operated by Petrobras in the Campos Basin, offshore Brazil, all contain slop water tanks, while some also have upstream oil-water separation tankage. Slop water, comprised of produced water, ballast water from oil cargo ships and deck water, contains SRB and their nutrients required for generating H2S. Additionally, solids accumulations at the tank bottoms provide an excellent environment for microbial growth.
A 2002 field trial on an FPSO confirmed the viability of combined batch treatments of anthraquinone and of a THPS blend to control H2S biogeneration better than previous treatment programs. Anthraquinone, a non-toxic SRB inhibitor, and THPS, an oilfield biocide, act synergistically to effectively control the H2S biogeneration in this environment. The combined chemical treatment strategy has now been implemented successfully on six Petrobras FPSOs. Flexibility has been important in developing the treatment programs since operating parameters are different for each FPSO and change due to increased water production rates. Options include the ability to inject the chemicals continuously or batchwise at different locations and to alter the volumes and ratios of chemicals for optimizing control over H2S and corrosion.
This paper describes the individual FPSO water flow and storage systems and discusses the customized chemical treatment programs. Included are field H2S data showing the progression of the programs as they are being continually adjusted to optimize H2S generation and cost effectiveness. Also included are results of laboratory microbial studies showing the synergy of anthraquinone and THPS and of corrosion studies which have impacted the direction of usage of these chemicals.
With over 100 FPSOs operating worldwide, the described treatment program can significantly affect the safety and environmental aspects of processing water containing SRB.
Experimental Investigation of Emulsions Stability in GOSPs—Part I: Analyses of Separated Phases
Authors: Al-Ghamdi A. M. , Noïk C. , Dalmazzone C. , Kokal S. 
Published: December 2007

Abstract
This paper presents the first part of an experimental study performed jointly by IFP and Saudi Aramco to characterize the stability of emulsion samples collected from different Saudi Aramco Gas/Oil Separation Plants (GOSP). Earlier studies1-2 have shown the importance of emulsion characteristics on the performance and optimization of oil-water separation at Saudi Aramco GOSPs. A strict and rigorous methodology was applied to understand the characteristics, behaviour and composition of these systems. Samples were first separated by simple gravity sedimentation in order to identify the amount of separated water, oil and residual emulsion. Each separated phase was then analyzed separately. This included the chemical composition and bulk properties of crude oil and the salinity of the separated water phase. Residual emulsions were characterized using several techniques including Karl Fisher analysis for water content, as well as optical microscopy, DSC (Differential Scanning Calorimetry) and cryo-SEM to assess the size and polydispersity of the dispersed droplets. The objective of the study is to highlight the main physico-chemical parameters responsible for the varying tightness of these emulsions, and provide insights to optimize their treatment costs and resolve emulsion issues in the GOSPs. The second part of this study still under progress will investigate the stability of residual emulsions in terms of chemical demulsification and interfacial properties.
A Program for Acid Formulation in Stimulation Jobs—Merging Oilfield Chemistry and IT Towards Development of "Smart" Fields
Authors: Gupta Adit 
Published: December 2007

Abstract
Acid formulation design for well stimulation requires careful experimentation for quantitative and qualitative identification of different elements present in spent acid and also mineralogical analysis of core samples. In depth lithological studies, experienced personnel and long discussion sessions are a prerequisite for finalization of acid formulation for wells, which proves to be a time consuming process. Development of an intelligent program proves to be an effective and time saving process for acid formulation of wells. Just the input of experimental results would give the necessary acid formulation design for the well. The program has an in-built database and decision making intelligence, which is based on the basics of reservoir stimulation (Basics like McLeod's table). The software can also deal with some exceptional wells. With the application of the software, the acid formulation design is achieved in minutes rather than in hours. Thus, the software proves to be an effective tool for the Oil industry where effective time and money management are the key ingredients for success.
Factors Determining the Reverse Osmosis Performance of Zeolite Membranes on Produced Water Purification
Authors: Liu Ning , Lu Jun , Li Liangxiong , Lee Robert 
Published: December 2007

Abstract
Purification of produced water by zeolite membranes is a novel technology reported recently for reclamation of produced water for beneficial use. Because of the extremely stable chemical, mechanical, and thermal properties, zeolite membranes show great advantages in difficult situations such as operations in a strong solvent environment, or those requiring high temperatures and high pressures. In this paper, we reported reverse osmosis (RO) permeation of solutions containing dissolved salts on a zeolite membrane. The influencing factors, including operating pressure, temperature, and ion concentration, on the RO performance of zeolite membranes are investigated. Potential application of the zeolite membrane technology in large-scale produced water purification is also discussed.
Nitrate-Based Souring Mitigation of Produced Water—Side Effects and Challenges from the Draugen Produced-Water ReInjection Pilot
Authors: Vik E. A. , Janbu A. O. , Garshol F. , Henninge L. B. , Engebretsen S. , Kuijvenhoven C. , Oilphant D. , Hendriks W. P. 
Published: December 2007

Abstract
Currently, the application of nitrate/nitrite is considered one of the most promising souring mitigation solutions during Produced Water Re-Injection (PWRI). Norske Shell tested nitrate based souring mitigation as part of a PWRI feasibility study in the Draugen field. Prior to the pilot, the application of both nitrite and nitrate had been tested on Draugen using a Souring Mitigation Cabinet (SMC) specially developed to mimic the microbial activity in the near well reservoir. From this pre-study, the dosage of nitrate was selected based upon bio-available carbon and the required stoichiometric concentration of nitrate.
During the PWRI pilot, corrosion rates were measured continuously Downstream (D/S) the Water Injection (WI) pumps in the High Pressure (HP) system, and after three months testing, significant increases in corrosion rates were seen. These were thought to be related with the addition of nitrate to the Produced Water (PW). To investigate this more closely, the SMC was modified by including a dedicated Low Pressure (LP) Corrosion Sidestream Monitoring (CSM) system. The results obtained in the CSM system verified the results obtained in the HP corrosion monitoring system in place on Draugen.
The results of the Draugen PWRI pilot also showed that the addition of nitrate to the PW was efficient to control near-well reservoir souring. However, as mentioned above the corrosion rates increased logarithmically when nitrate was used. At the same time, a few ppm nitrite was seen in the nitrate treated PW water. The addition of biocide resulted in an instantaneous decrease in nitrite and corrosion rates to background levels. The result clearly indicates that bacterial activity, resulting from the addition of nitrate, was the causative agent of the increased corrosion seen in the Draugen PW treated for re-injection. It was concluded that the increase in corrosion rates most likely was Microbiologically Influenced Corrosion (MIC). Details of the PWRI pilot and the observed effects when applying nitrate are discussed in this paper.
Because of the negative side-effects observed when applying nitrate to PW, Norske Shell re-evaluated the requirement to mitigate souring with nitrate. The testing during the PWRI pilot showed a low tendency to develop SRB activity, probably because of the low VFA concentration in the PW. Consequently it was decided to terminate the application of nitrate to PW on Draugen and control bacterial activity in the surface facilites with biocide.
As nitrate is still promising to be applied in PW in other field applications, dedicated research has been initiated to learn more about the mechanisms leading to the increased corrosion rates seen when applying nitrate in PW.
Using the EnKF for Assisted History Matching of a North Sea Reservoir Model
Authors: Evensen G. , Hove J. , Meisingset H. C. , Reiso E. , Seim K. S. , Espelid Ø. 
Published: December 2007

Abstract
The ensemble Kalman filter (EnKF) has been used for history matching a simulation model of a North Sea reservoir. Parameters such as initial fluid contacts, vertical transmissivity multipliers and fault transmissivity multipliers have been estimated as well as 3D fields of porosity and permeability.
It is shown that for several of the parameters a large initial uncertainty is reduced to an acceptable level by the assimilation of well-log measurements and production rates of oil, gas and water. The result is an ensemble of history matched realizations which can be used to predict the uncertainty in future production.
It is also shown that the formulation used in the EnKF reduces a nonlinear minimization problem in a huge parameter space, involving the minimization of an objective function with multiple local minima, to a statistical minimization problem in the ensemble space. Thus, by searching for the mean rather than the mode of the posterior pdf, the method avoids getting trapped in local minima and is thus promising for history matching reservoir simulation models.
Furthermore, the EnKF provides an ideal setting for operational reservoir monitoring and prediction, including proper representation and prediction of uncertainty.
On-Site Freshwater Production for Offshore Facilities
Authors: Osegovic J. P. , Hill J. W. , Tatro S. R. , Max M. D. 
Published: December 2007

Abstract
Natural supplies of fresh water are limited while the demand for fresh water is increasing worldwide. Production of fresh water at sea is often achieved through a restricted group of conventional desalination technologies including reverse osmosis and modern versions of distillation. Two methods of unconventional water production, one of which is based on the unique set of resources available at an operating production platform, may provide solutions for provision of potable water and for industrial dewatering of process water.
Effects of Flow Conditions and Surfactant Availability on Adsorption
Authors: Grigg Reid B. , Mikhalin Alexander A. 
Published: December 2007

Abstract
Anionic surfactants, good foaming agents, can be used in CO2 foam flooding to improve high-pressure, high-density CO2 reservoir sweep efficiency. In this study, kinetics and equilibrium adsorption were investigated by examining adsorption behavior in a system of solid phase sandstone or limestone and of an aqueous phase of surfactant in 2% brine. Effects on surfactant adsorption density for different solid to liquid ratios as well as surfactant concentration, rock type and state, and flow conditions are presented. Three systems were used: batch tests on crushed rock, circulation tests through core samples, and non-flow, diffusion brine-saturated core tests. The density of an anionic surfactant adsorption on rock is best described as a function of surfactant available in the system (concentration plus volume), rather than by surfactant concentration used by previous investigators. Experiments with solid rock were carried out to determine surfactant capacity of the porous media through flow and non-flow rock samples and crushed rock samples. Adsorption was similar for crushed sandstone and flow tests, while significantly higher in cubed, non-flow rock systems. For limestone the crushed rock and non-flow systems were similar while the flow system was significantly lower. The time to reach equilibrium required less than one hour (generally minutes) for the crushed rock, hours to days for the flow-through tests, and weeks to over a month for the non-flow rock systems. The rate of adsorption dependent on availability (delivery) that is generally much slower than the adsorption kinetics.
Design and Evaluation of an Elastomeric Sealant for Use in Primary Cementing
Authors: Phipps J. S. , Ladva H. K. J. , Craster B. , Caritey J. -P. , Dargaud B. 
Published: December 2007

Abstract
We describe the design and development of an elastomeric sealant for improved zonal isolation. The sealant is intended for use during primary cementing, and has been formulated so that it can be pumped as part of the cement train and placed around the shoe of a casing. In this way reliable isolation at key points in the well can be achieved without incurring excessive costs. The mechanical property specifications of the sealant have been determined using stress analysis; we show how a sufficiently deformable material remains effectively confined by the wellbore and thus cannot be subjected to tensile stresses that could cause its failure, and that it needs to be held in a state of compressive stress in order to prevent gas leakage. By applying pressure to the sealant during curing and allowing it to expand thermally afterwards, a suitable state of compression can in principle be generated. The necessary control over the rheology, density and curing time of the sealant to enable its reliable placement has been achieved. The effect of the initial stress state and the performance of the sealant compared with cement-based materials are demonstrated in a full-scale test.