bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Geologic Parameters on CO2 Storage in Deep Saline Aquifers
Authors: Mo S. , Zweigel P. , Lindeberg E. , Akervoll I. 
Published: December 2007

Abstract
The results of modeling injection into and long-term storage of CO2 in a deep saline aquifer with a commercial black-oil reservoir simulator are presented. Realistic CO2/water pVT properties covering all pressure, temperature and compositional conditions accounted for during the simulations have been used. The pressure and temperature in the aquifer is above the CO2 critical pressure and temperature giving rise to the existence of a two-phase fluid system of CO2 as a fluid and an aqueous phase containing dissolved CO . The impact of CO2 injection rate, reservoir layering, capillary pressure and residual CO2 saturation for water re-entering CO2 filled volumes (hysteresis in fluid saturations) on CO2 distribution and storage in the deposit have been studied. The re-distribution of water occurs after stop of CO2 injection due to gravity segregation of denser CO2 saturated water and CO2-free water.
For upscaling studies a small section of the reservoir model (typically a reservoir grid block) was finely gridded and studied separately for various reservoir parameters and injection rates. The fine model showed that the sweep efficiency of CO2 displacing saline water and both position and quantity of CO2 in each grid block of the reservoir model are sensitive to the CO2 injection rate and the effective vertical permeability. By increasing the viscous to gravity force ratio, the sweep efficiency increases resulting in more CO2 trapped as residual gas. More CO2 is also trapped in the case of increasing CO2-water capillary pressure. Estimating the amount of trapped CO2 from the average CO2 saturation is possible when the sweep efficiency is good (evenly distributed CO2) but may give bad estimates when CO2 only enters part of each large grid block. This shows that to get reliable estimates of the amount of trapped CO2 the distribution of CO2 in each grid block is important and the traditional upscaling methods have to be extended to incorporate the effect of CO2 distribution on trapped gas. Especially the effect of fine-scale layering must be upscaled properly.
Transient Flow in Naturally Fractured Reservoirs and its Application to Devonian Gas Shales
Authors: Kucuk Fikri , Sawyer Walter K. 
Published: December 2007

ABSTRACT
For many years gas has been produced naturally from Devonian shales throughout the Appalachian Basin at rates which made them commercially feasible. In 1975, because of the deteriorating gas supply situation in the United States and increasing demand for energy, the U.S. Department of Energy (DOE) established the Eastern Gas Shales Project (EGSP) as part of the Unconventional Gas Recovery (UGR) program to study and characterize and to develop economically feasible technology for further exploitation of Devonian shale gas reservoirs.
Devonian shale gas reservoirs typically are characterized by a low storage, high flow-capacity natural fracture system fed by a high storage, low flow-capacity rock matrix. In this study analytical solutions are developed to analyze the basic fractured reservoir parameters that control well productivity. These parameters include fracture system porosity and permeability, matrix porosity and permeability, and matrix size.
It is shown that the conventional well test method does not usually work for fractured Devonian shale gas reservoirs. For most cases, the semilog plot of the drawdown and buildup data does not show two parallel straight lines with a vertical separation.
Numerical solutions are also used to include the Klinkenberg effect and desorption in the shale matrix.
Integrated Reservoir Characterization for the Redevelopment of a Highly Complex Field
Authors: Badessich M. F. , Gait M. , Carbone C. , Dzelalija F. , Giampaoli P. 
Published: December 2007

Abstract
This paper is a case study of the redevelopment of a highly complex and heterogeneous reservoir located in the folded belt of Neuquén basin, Argentina. The objective is to describe the integrated reservoir study that was performed; as a consequence, an aggressive drilling campaign was implemented which derived in a boost in production with no substantial interference among wells.
The field was in a mature stage as it came into production in 1984 by primary recovery and oil rate was declining steadily.
Cerro Fortunoso field represents a challenge for optimising the depletion strategy because of its non conventional qualities such as the presence of an under-saturated oil in coexistence with an extensive CO2 gas cap, the heavy oil located in a highly heterogeneous fluvial reservoir with poor petrophysical conditions and flanks dipping more than 60 degrees. Besides good data acquisition for seismic is hindered by surface volcanic rocks and complex geology.
Field operation is intricate because it is placed in a natural reserve; as a result, drilling and production activities are more expensive in order to comply with environmental regulations.
As the reserve to production ratio was exceptionally high compared to other fields in the area, it was suggested that production could be increased but the challenge was how to accomplish this objective in a supposedly fully developed reservoir where the low productivity of the wells had a profound impact on economics.
The multidisciplinary team concluded that both the geological and engineering features contributed to a low recovery factor which could be improved by infill drilling. New technology was used to drill 9 vertical and 16 deviated wells in only two years. The results were so spectacular that it not only arrested decline but also established a new peak of production.
The conclusions show that many fields that are thought to be fully developed, still have a lot of new oil to be produced. Reservoir management plays a major role by improving final recovery and project economics.
An Analytical Study of Transient Flow in Systems with Radial Discontinuities
Authors: Satman Abdurrahman , Mauricio Eggenschwiler , Tang Ray W-K , Ramey H. J. 
Published: December 2007

ABSTRACT
A recent study of pressure falloff for steam injection and air injection in thermal recovery yielded surprising results. It was possible to measure the volume of the gas-filled displaced region with accuracy, and the method did not depend upon regular geometry for the displaced region. This meant it was possible to detect fuel concentration in forward combustion or perhaps vertical heat loss in continuous steam injection by using a pressure transient test. There also appeared to be other potential applications for enhanced oil recovery. An initial paper on this subject was presented at the California Regional Meeting in April 1980.10 This paper is an extension of that study.
The new solution described in this paper is an analytical solution for a circular well with a skin effect and wellbore storage. The well is in a composite system with a circular inner region whose conductivity and diffusivity are different from those in the outer region. There may be either a constant pressure, closed, or infinitely-distant outer boundary. The solution method is Laplace transformation followed by both numerical and analytical inversion. Most graphs and results were obtained by numerical inversion.
Solutions were compared with previously published Bixel and van Poollen results.6 They presented the figures of pD versus tD for different values of the diffusivity ratio and mobility ratio. However, apparently only one value of the radial discontinuity was used in developing the results. In the present study, the dimensionless figures of pD versus tD for various values of radial discontinuity and also for a well with a skin factor and wellbore storage were developed.
Early results of the present work indicated that the system with the radial discontinuity behaved like a closed system prior to the beginning of the semilog straight line of the second region. This paper discusses the evaluation of the dimensionless form of the solution in terms of parameters such as mobility and diffusivity ratios and the magnitude of the radial discountinutiy.
Development of Systematic Hydraulic Fracturing Technology for a Naturally Fractured Reservoir
Authors: Zhao Z. , Liu D. , Liu W. , Chai L. , Zhou H. 
Published: December 2007

Abstract
Reservoir N is a typical low-permeability buried-hill fractured reservoir with oil-bearing area of 3.6Km2, OOIP of 973 × 104t and buried depth of -1700 ~ -2500m.Its oil bearing interval is longer, between 125 ~ 410m.Its average porosity is 5.1% and average permeability is 23.6× 10−3µm2. Due to the insufficient natural energy, its pressure coefficient is 0.98. As the economic yield can't be achieved by conventional technologies, the reservoir must be fractured integrally. Following technologies have been applied in the field. Based on early and proper water injection, supplementing formation energy and maintaining formation pressure, fracturing and waterflooding are combined reasonably to improve waterflooding sweep efficiency and avoid watering out and water channeling at the same time; the concept of optimizing fracturing design for high sand content, large discharge capacity, medium and low proppant concentration and medium and long fractures is established so that artificial fractures can be communicated with natural fractures and a complete interconnected system can be formed by pores, artificial and natural fractures in the reservoir; with the method of perforating short intervals, avoiding perforating long intervals and staged fracturing, the whole oil-bearing interval is divided into 2 to 4 fracturing units which are fractured from bottom to up till all the interval are fractured; silt is used as the fracturing fluid loss additive to reduce excessive fracturing fluid loss and used for propping fractures and connecting major fractures and natural microfractures. Reservoir N has been fractured for 96 times by this method with cumulative oil production of 98.3 × 104t. Field applications indicate that the method of integral fracturing development is also suitable for the low-permeability fractured sandstone reservoirs which are similar to Reservoir N and good development effects have been got.
A TFL Caliper for use in Subsea Flowlines and Wells
Authors: Pierce Aaron E. , Rickey W. P. , Dieckman H. E. 
Published: December 2007

Abstract
A pumpdown caliper1 has been designed, built and successfully field tested and is now commercially available for worldwide use. The tool is self contained and utilizes the features of the standard wireline version of the Kinley caliper.2 It is designed for use in 3 and 4-inch inside diameter (I.D.) tubing and will measure discrepancies in the pipe as small as 0.03-inch. The tool can be used for surveying subsea wells equipped for through flowline (TFL) and for horizontal flowlines on land. Both types of applications have been successfully tested under field conditions.
Evaluating the Magnitude of Time-Lapse Effects Through 4D Core Tests: Lessons From a North Sea Reservoir
Authors: Golfetto F. , Meazza O. , Sturniolo A. 
Published: December 2007

Abstract
Quantifying the expected acoustic changes induced by production is crucial for the success of any 4D reservoir monitoring project.
To this end, 4D core measurements performed by simulating in Laboratory the varying conditions occurred during the life of a field provide the magnitude of these changes. Experience made for a North Sea reservoir shows the significance and validity of such measurements.
"Systems Analysis" Use for the Design and Evaluation of High-Rate Gas Wells
Authors: Crouch E. C. , Pack K. J. 
Published: December 2007

ABSTRACT
The use of "Systems Analysis" curves has proved to be a valuable tool when designing high rate gas completions and evaluating well performance. This paper presents the practical application of "Systems Analysis" when used in gravel pack completion design and shows several case histories of actual performance of high rate gas wells in the Gulf of Mexico.
The Relationship between Clean Fluids & Effective Completions
Authors: Rike James L. 
Published: December 2007

ABSTRACT
The preponderance of evidence shows chat completion effectiveness, and especially well productivity, is directly related to the use of clean completion and workover fluids.
Even small amounts of solids (500 ppm) in completion and workover fluids can be enough co bridge in perforation tunnels, in channels behind pipe, and in gravel packs and in propped fractures. This plugging is responsible for many wells producing at 10-85% of full potential; for multiple squeeze attempts so often necessary to successfully seal cement channels; and for sticking pipe during concentric tubing operations.
It is a widely held myth among industry operations personnel that plugging material is easily removed with reactive materials such as HF acid in the case of clay solids or HCl acid in the case of carbonate solids.
Tests and field experience indicate that significant increases in flow conductivity are obtained not only with clean fluids instead of muds and dirty fluids, but also when larger pressure differentials into the wellbore exist while perforating.
Improved Coarse Grid Generation Using Vorticity
Authors: Mahani H. , Muggeridge A. H. 
Published: December 2007

Abstract
This paper describes the use of vorticity to optimize the generation of coarse simulation grids from finely gridded geological models, thereby reducing (or removing) the need for two phase upscaling. Vorticity has been used in the simulation of flow in porous media since de Josselin de Jong1 first discussed it in 1960. However this is the first time, to our knowledge, that it has been used in the area of upscaling.
Vorticity maps are generated from simulations of single-phase flow in the finely gridded geological model of interest. A coarse simulation grid is then derived which is more refined in areas of high vorticity and coarser in areas of low vorticity. The method is demonstrated for simple, layered and lens heterogeneities as well as Model 1 from the SPE Comparative Study in Upscaling2. Good matches between fine and coarse grid simulations of waterflooding are obtained, compared with using a conventionally generated coarse grid model.
Significant Production Enhancement in Uzen Field, Kazakhstan through Surface and Subsurface Optimization
Authors: Sparke S. J. , Kislyakov P. Y. , Amirtayev M. A. 
Published: December 2007

Abstract
This paper describes the optimisation through production engineering of the rehabilitation of Block 3A in the Uzen Field, Kazakhstan.
The Uzen field is located onshore adjacent to the Caspian Sea and was discovered in 1961 with initially estimated oil in place of 8,400 million barrels (MMBBLS). By the 1970s, the Uzen Field was contributing 320,000 barrels oil per day (bopd) to the Soviet system and was considered to be one of the largest producing assets in the USSR. However, due to both political and economic instability and underinvestment in the 1990s, production levels declined to 52,000 bopd. To restore the oilfield to its former levels of production would require an intensive field wide work programme costing a significant amount of money.
In 1995, the Kazakhstan Government applied for a World Bank loan to fund a pilot rehabilitation project on one area of the field, a premier production unit. This loan utilised a multidisciplinary service team that was equivalent to a small oil company. The programme of work, initiated during the second quarter of 2000, was focused on workovers and surface facilities, production optimisation procedures, the application of new technologies and targeting engineering solutions.
At the conclusion of the consulting contract after 3.5 years of work in November 2003, production from Block 3A had been increased from 8,000 bopd to 16,000 bopd. In conjunction with the rehabilitation project, an extensive training programme was undertaken for all staff in the host field management and field organisation, the knowledge base of which was successfully transferred to the rest of the field.
It has also been demonstrated that these achievements reconciled logistical, cultural and management-style differences through the use of fit for purpose technology and the introduction of effective decision making procedures in conjunction with change management and intensive on-the-job training.
Practical Approach to Volume Requirements for Air and Gas Drilling
Authors: Ikoku Chi U. , Azar J. J. , Williams C. Ray 
Published: December 2007

ABSTRACT
Air, mist, foam, and other variations of aerated fluid drilling are utilized in various areas because of the improved penetration rate when compared to conventional mud drilling. Other proven advantages include immediate and continuous evaluation of cuttings for hydrocarbon shows, low cost, longer bit life, better control in cavernous and lost circulation areas, and minimum damage to liquid sensitive pay zones. The high compressibility of aerated drilling fluids and multiphase flow phenomena encountered when using these fluids have given rise to sophisticated engineering approach to achieve proper downhole cleaning and material transport.
There have been several attempts to calculate the minimum volumetric requirements for air and gas drilling. The results of these studies are valid over limited ranges of drilling rates at best. The reason is that there are so many variables involved in an air or mist drilling situation that one general correlation has not been developed to explain what is happening downhole and predict appropriate air or gas injection rates in the field. The method described in this paper will permit the driller and drilling engineer to determine optimum fluid injection rates in the field. It eliminates the need for complicated flow calculations used to predict volumetric air requirements.
Integrated Workflow for Quantitative Use of Time-Lapse Seismic Data in History Matching: A North Sea Field Case
Authors: Haverl M. C. , Aga M. , Reiso E. 
Published: December 2007

Abstract
This paper shows the implementation of a workflow for quantitative use of time-lapse seismic data in computer-ssisted history matching of simulation models.
The use of time-lapse seismic data alone or combined with production data gives additional valuable information about the reservoir and its behaviour. Several field examples of successful qualitative use of time-lapse seismic data exist. However a quantitative integration in the history-matching loop, considering all different types of scale along with measurement uncertainties, still represents a challenging task.
We present the workflow applied in a real North Sea field case, where production data and inverted seismic data from two surveys are utilized. An implemented petro-elastic model converts from reservoir to seismic parameters. Commercial optimization software is used to minimize the difference between observed and simulated data and to update the reservoir model parameters.
The main focus is to identify, understand and quantify the uncertainties in the data and the model at each step of the workflow. A key to success is tight communication and teamwork between geophysicists and reservoir engineers.
Results show that including information from time-lapse seismic data in the history matching process gives us a better understanding and description of the reservoir performance and an optimized static and dynamic reservoir model.
Identifying Wellbore Damage Components through Discrete Fracture Network (DFN) Models
Authors: Araujo H. , Lacentre P. , Zapata T. , Del Monte A. , Dzelalija F. , Gilman J. , Meng H.-Z. , Kazemi H. , Ozkan E. 
Published: December 2007

AbstractThe wellbore damage components, in a naturally fractured reservoir, were studied by means of a combined interpretation using conventional analysis, and a dual-porosity numerical simulation of a Discrete Fracture Network (DFN) model. The common cause for this additional pressure drop in naturally fractured reservoirs is the skin damage and turbulence effect. The dynamic behavior of the discrete fractures model was first studied by simulating, with the numerical model, the pressure response of the production history measured during a multi-rate test data. Multiple simulation runs provided pressure outputs, comparing them with the observed pressures, until achieving an acceptable match. A detailed calibration of the fracture model properties were done by analyzing the pressure change and derivative of the numerical simulation pressure output results. During the calibration of the fractures properties it was found that extra pressure drop near the wellbore was required. To reproduce such extra pressure drop, the near wellbore cells of the numerical model were calibrated under several conditions. This paper shows how a fine-grid simulation, DFN based model and the conventional well test interpretation methods were combined to evaluate the damage components affecting the fractures intersecting the wellbore.
Planning EOR Projects in Offshore Oil Fields
Authors: Bondor P. L. , Hite J. R. , Avasthi S. M. 
Published: December 2007

Abstract
Enhanced Oil Recovery (EOR) technologies can significantly increase recovery from oil reservoirs.Some of these EOR technologies are currently producing substantial incremental oil, primarily in onshore applications; others have not yet made a commercial impact. The application of these methods is more complex in the offshore environment, as space and weight restrictions, as well as the need for high reliability and the challenging economics of such projects, impose constraints not present in onshore applications.All EOR processes are reservoir- and reservoir fluid-specific; thus it is necessary to identify the appropriate EOR technology for use in a reservoir, design the project to achieve the required economic incremental recovery within the constraints imposed by the offshore environment, and manage the project to meet or exceed expectations.
This paper will focus on the impact of the offshore environment on the planning, design and management of an EOR project.
Spectral Gamma-Ray (KUT) Borehole Logging
Authors: Young John H. 
Published: December 2007

ABSTRACT
Natural gamma-ray borehole logging is a recognized technique for evaluating uranium deposits and providing lithographic data. Spectral gamma-ray (KUT) borehole logging is a refinement of the technique which categorizes gamma-rays, according to their energies, as coming from Potassium (K), uranium (U), and thorium (T). This spectral information enhances the usefulness of the natural gamma-ray log by providing additional information on the composition of the formation producing the gamma-rays.
KUT logging is particularly applicable to evaluation of low-grade uranium deposits, and to cases where thorium anomalies are suspected. The ability to identify potassium and thorium can also aid in the classification of many rock strata.
Calibration of a spectral gamma-ray probe for proper sensitivity to gamma-ray energy is of particular concern in KUT logging. A means of continuously controlling the sensitivity of a KUT probe, using a computer and a manganese-54 reference source, is described.
Evaluation of elemental concentrations of potassium, equivalent uranium, and equivalent thorium, involves applying a stripping matrix of nine factors to the raw count rate data from the probe. Both the raw count rate data and the concentration data can be plotted versus depth. This evaluation procedure and the calibration method which yields the stripping matrix are described. Accuracy of the data produced, and the effect of logging rate on accuracy, are also discussed.