bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the Continuous Annular Monitoring Concept To Prevent Groundwater Contamination by Class II Injection Wells
Authors: Janson L. G. , Wilson E. M. 
Published: December 2007

ABSTRACT
This paper will present a continuous annular monitoring concept that allows Class II injection wells that have insignificant leaks in the casing to demonstrate mechanical integrity. Inherent in this concept is the premise that an insignificant leak in the casing is any leak that will not endanger a USDW and that this test will therefore meet the regulatory requirements under 40 CFR 146.8 (a) and (b). A case history will be presented to demonstrate the viability of this concept as an alternative mechanical integrity test. This concept has been approved as an alternate mechanical integrity test by the Regional Administrator of USEPA Region 6 for use in the Osage Mineral Reserve under 40 CFR 147.2912 (a)(1)(V).
Predicting Oxygen Depletion in Reservoir Environments
Authors: Welch V. S. , Dann M. W. , Mehta B. 
Published: December 2007

ABSTRACT
Iron pyrite (FeS2; ferric sulfide; "Fool’s Gold") is one of the most common of all naturally occurring minerals in sedimentary rock. Any reservoir process involving oxygen (air) might be affected by the aqueous oxidation of pyrite in the reservoir. During this reaction, one mole of pyrite can consume 3.75 moles of oxygen, or the equivalent of all the oxygen present in 6,469 SCF (183 m3) of air. Reservoir pH may be reduced significantly by the major reaction product, sulfuric acid. The precipitation of ferrous hydroxide may cause permeability reduction.
This paper discusses the case history of a pilot air storage test, the results of laboratory studies which identified pyrite as the prime suspect for the oxygen loss during the test, the reaction stoichiometry for the reservoir environment studied, laboratory equipment and procedures used to test synthetic sand-pyrite mixtures and core plugs for oxygen consumption, and the empirical relationship which was derived to predict oxygen consumption.
Reservoir Description and Steamflood Development in the Lost Hills Field
Authors: Chiou R. C. S. , Kirst T. L. , Kiven C. W. 
Published: December 2007

Abstract
A steamflood was developed in the Lost Hills field, located in the southwest portion of the San Joaquin Basin in California. The heavy oil reservoirs consist of shallow-marine Upper Etchegoin sands overlain by the fluvio-lacustrine Tulare formation. Steamflood development was complicated by the presence of desaturated zones in both the Tulare and Upper Etchegoin sands. Core analyses, density-neutron logs, and temperature profiles aided in the identification of three genetically different types of desaturation: 1) gravity drainage response to anticlinal growth and/or regional uplift, 2) possible paleo-oil seeps related to an unconformity, and 3) production depletion due to nearby thermal operations. Reservoir mapping indicates that the the first type of desaturation was widespread in the Upper Tulare sand. This type of desaturation not only significantly reduced the oil-in-place, but could also become a major thermal thief zone. Steamflood patterns and well completions were designed to minimize the effect of desaturation and maximize the project efficiency. The design and development of the steamflood may be applied to other partially desaturated, multiple sand reservoirs.
Evaluation of Geostatistical Techniques for Reservoir Characterization
Authors: Chopra A. K. , Severson C. D. , Carhart S. R. 
Published: December 2007

Abstract
One of the most important problems in reservoir management and EOR applications is to describe interwell heterogeneity for optimum well spacing and process design. The conventional approaches to build reservoir descriptions use interpolation schemes based on the geometric distance of the samples. In geostatistics, on the other hand, the interpolated values depend on geometric orientation and correlation. Geostatistics has been used in the mining industry for the past forty years and in hydrogeology for the past twenty years. However, its application has been limited in reservoir engineering because of skepticism due to a lack of needed data and the absence of comparisons with the conventional techniques.
Conventional and geostatistical reservoir characterization techniques are compared in this paper. Field data from about 50 wells are used in this evaluation. Interwell properties are computed using conventional and geostatistical techniques, cross-validated, and compared. Histograms show there are no geographically distinct populations requiring separate modeling. Experimental variograms identify the scales of variability of the reservoir properties and the existence of preferential directions of maximum and minimum variability. Variogram models are fitted to the experimental correlations.
The results of this work indicate that the success of any technique is a function of the geological environment, selection of proper reservoir parameters for that environment, an adequate number of samples, an appropriate sample spacing, and most importantly, the correct application of the technique. Geostatistical techniques have more potential to incorporate the underlying correlation present in the data in the final analysis.
General Coning Correlations Based on Mechanistic Studies
Authors: Lee S. H. , Tung W. B. 
Published: December 2007

ABSTRACT
The coning of water can impact well productivity and increase water treatment requirements. Coning correlations are often used to model water-breakthrough time and water cut due to coning. Most existing coning correlations are based on a steady state approximation so that the prediction of water-breakthrough time and initial water cut development are generally unreliable. By first determining the key reservoir, production, and well completion parameters through a theoretical analysis, improved correlations were developed. They have been extensively compared with numerical simulation results to validate their general applicability. The correlations simplify the procedure in the study of the effects of production rate, vertical and horizontal permeabilities, well completion location, physical properties of fluids, relative permeabilities, aquifer thickness, completion interval size, and drainage radius on coning dynamics.
The new correlations can be used in a stand-alone program or in reservoir simulation. In field-scale reservoir simulation, correlations are often employed to model sub-scale flow behavior near a well. Hence, technical issues in implementing correlations into a finite difference simulator are also discussed. In addition, the new correlations are extended to multi-layered, nonhomogeneous reservoir models.
A New Adaptive Orthogonal Grid Generation Procedure for Reservoir Simulation
Authors: Sharpe H. N. , Anderson D. A. 
Published: December 2007

ABSTRACT
The generation of boundary conforming, orthogonal, smooth curvilinear grid systems for regions containing internal boundaries, which can also cluster dynamically to physical solution gradients, is of major importance to reservoir simulation. This paper develops a practical methodology for achieving these objectives for two-dimensional problems. The procedure is based on elliptic mapping methods and equidistribution schemes. The extension to 3–D is simple for thin reservoirs.
Implementation of a Reservoir Management Program
Authors: Thakur G. C. 
Published: December 2007

ABSTRACT
Reservoir management can be defined as the judicious use of various means available to maximize benefits or economic recovery from a reservoir. Although there are numerous reasons why reservoir management programs sometimes do not succeed, perhaps the most important reason is the lack of team effort in developing and implementing such programs. A step-by-step procedure to improve success in this effort is outlined.
Two distinct approaches have been utilized: one is a comprehensive approach for large reservoirs and the other is a problem solving approach for small (and/or less profitable) reservoirs. Although the approaches are philosophically quite different, each has produced useful results. It is not necessary for all reservoirs to have the most comprehensive management program; rather, it should be dictated based upon need, keeping the cost-benefit analysis in mind.
Geostatistics for Reservoir Characterization
Authors: Journel A. G. 
Published: December 2007

Abstract
Geostatistics and, more specifically, stochastic modeling of reservoir heterogeneities are being increasingly considered by reservoir analysts and engineers for their potential in generating more accurate reservoir models together with usable measures of spatial uncertainty. Geostatistics provides a probabilistic framework and a toolbox for data analysis with early integration of information. The uncertainty about the spatial distribution of critical reservoir parameters is modeled and transferred all the way to a risk-conscious reservoir management. The stochastic imaging (modeling) algorithms allow the generation of multiple, equiprobable, unsmoothed reservoir models yet all honoring the data available.
Remobilization of Natural Gas Trapped by Encroaching Water
Authors: Ancell K. L. , Trousil P. M. 
Published: December 2007

ABSTRACT
Water drive gas reservoirs are frequently abandoned at high pressures which results in low recovery of the initial gas in place. The gas remaining in these reservoirs is trapped as residual gas saturation. The techniques to remobilize a portion of this gas that has been trapped by encroaching water are presented along with a method to evaluate the incremental reserve potential of such reservoirs. The remobilization of the trapped gas requires the production of large volumes of water to lower the reservoir pressure which in turn allows the gas to expand and flow.
A new use of the p/z vs cumulative production chart is presented which gives the engineer a quick method to evaluate the feasibility of recovering a portion of the gas that has been trapped by water influx.
A field example is presented which illustrates the concepts and techniques. Presented is field data that demonstrates the remobilization of gas that had been trapped by encroaching water. Significant increases in recovery have been experienced at the demonstration field, and ultimate recovery is estimated to be about 8% of initial gas in place greater than was recovered using conventional practices. Also given are actual operating costs and revenue calculations that show the process to be economic at 1990 market prices.
Using Depletion Ratios To Select and Evaluate Drilling Locations in Naturally Fractured Gas Reservoirs
Authors: Hower T. L. 
Published: December 2007

Abstract
A reservoir characterization technique is presented which can significantly lower the risk involved in developing naturally fractured gas reservoirs. It is shown that depletion ratios can be used to delineate the limits of a field, highlight the prolific trends often associated with naturally fractured reservoirs, and provide a simple, yet accurate, means of assigning reserves to undrilled locations.
A field case history is described and the results of a successful twenty well drilling program are presented. Pre-drill reserve estimates for the entire program were within seven percent of the actual post-drill reserve estimates from production decline analysis.
A Comparison of Mass Rate and Steam Quality Reductions To Optimize Steamflood Performance
Authors: Messner G. L. 
Published: December 2007

Abstract
Most mature steamflood projects have the heat injection rates reduced to minimize fuel costs and extend the economic life of the project. However, there is little industry consensus on whether the heat cuts should take the form of 1) mass rate reductions while maintaining the same high steam quality, or 2) steam quality decreases while keeping the same mass rate. Using a commercial three-phase, three-dimensional simulator, oil recovery schedules were generated for several steam mass rate and quality reduction cases under a variety of reservoir and operating conditions. The results indicated that for equivalent heat injection rates, decreasing the steam injection mass rate at a constant high quality will yield more economic oil than reducing the steam quality at a constant mass rate. A sensitivity analysis confirmed this conclusion and demonstrated the importance of the gravity drainage/steam zone expansion mechanism in a low-pressure, heavy oil steamflood with gravity segregation. Furthermore, the impact of discontinuous silts and non-uniform initial temperatures within the steamflood zone was studied, again indicating that a decreasing mass rate injection strategy is a superior operating practice.
Optimal Reduction of the Analytical Data Necessary for the Thermodynamic Characterization of Natural Gases
Authors: Ruffier-Meray V. , Barreau A. , Behar E. 
Published: December 2007

Abstract
Analytical procedures presently available lead to a large amount of compositional data when applied to reservoir fluids. Even though it can be considered to use all these informations as input for thermodynamic models when research is carried on how to improve their predictions, this use is no more possible in big reservoir simulators because the computation cost would become prohibitive, as these call thermodynamic subroutines a great number of times. It is thus necessary to reduce analytical data in order to get an optimal ratio (accuracy/computing time) while calculating the thermodynamic properties of natural gases.
In the work described here, we have compared different lumping procedures as well as thermodynamic characterization methods of the obtained fractions, and propose a way to quantify the loss of accuracy resulting from the reduction of the analytical data.
In order to avoid any bias due to modelling (analytically and thermodynamically) real natural gases, the comparison has been performed with synthetic fluids. After having selected the best lumping method amongst those tested, the whole procedure has been applied and checked in the case of a condensate gas produced from a North Sea reservoir.
The Gavilan Field: Inverse Rate Sensitivity in Dual-Porosity Reservoirs
Authors: Hueni G. B. , Jones R. E. , Fitzgerald K. M. , Kohlhaas C. A. 
Published: December 2007

Abstract
The Gavilan Mancos Pool, located in the San Juan Basin of New Mexico, produces from the Niobrara siltstone interval within the Mancos Shale. This type of reservoir in this area has previously been described as a fractured shale in which the matrix has been assumed not to contribute to low porosity and low permeability. This paper discusses the dual porosity character of the formation and shows the method in which the dual porosity nature of the reservoir was identified. The identification process reflects an integration of all available information including geologic description, core analysis results, pressure buildup analysis and a review of performance history. The presence of capillary pressure effects give rise to inverse rate sensitivity behavior in which the gas-oil ratio declines at higher withdrawal rates. Maintaining maximum withdrawal rates in this reservoir increases ultimate recovery by one-half percent of oil in place, which is an increase of approximately 4 percent of recoverable oil.
Development and Operational Planning for a Fractured, Gas-Condensate Reservoir With a Thin Oil Column, Szeghalom Field, Hungary
Authors: Lumsden G. H. , Black P. J. , Troemboeczky S. , Mobarak S. A. , Falucskai L. , Carnes A. C. 
Published: December 2007

Abstract
The Szeghalom field contains gas condensate and oil in two faulted, anticlinal structures separated by a saddle. The larger structure has a gas column in excess of 200 m [656 ft] thick which is underlain by a 23-m [75-ft] oil column. The reservoir interval consists of metamorphosed and fractured Precambrian basement rocks which are intermixed and overlain in most areas of the field by basement breccias, which in turn are overlain by sedimentary Miocene sandstones, conglomerates, and carbonates.
Reservoir performance was simulated using a three-dimensional, three-phase, compositional, dual-porosity, dual-permeability reservoir simulator. After matching history, the model was used to predict performance under four different operating plans: (1) Natural depletion; (2) Cycling of produced gas; (3) Pressure maintenance by CO2 rich gas injection; and (4) Partial gas storage followed by full gas storage.
Conceptual facilities design and cash flow projections were prepared for all prediction cases. All methods of operation were shown to have profit potential, but natural depletion is the clear choice from an economic viewpoint.
Determining Downhole Flow Rates of Oil and Gas in Oil Wells Using Pressure Drop and Spinner Response Measurements
Authors: Gang X. Z. , Golan M. , Sveen J. 
Published: December 2007

ABSTRACT
This paper presents a method that improves the current practice of interpreting downhole pressure drop and spinner response measurements. Two mathematical models have been developed, one relating the flow rate of each phase to the spinner response and the other relating the rates to the measured pressure drop. Simultaneous solution of the two models with measured data determines the in-situ flow rate of gas and liquid phase with minimum interpretation assumptions. Laboratory experiment performed in a large scale flow loop using commercial logging tools validated the method and substantiated the theoretical considerations involved.
Hydraulic Optimization of PDC Bits
Authors: King I. , Bratu C. , Delbast B. , Besson A. , Chabard J. P. 
Published: December 2007

ABSTRACT
The aim of our work is to improve the understanding of flow distribution and determine the optimum set of hydraulic design parameters that favour the drilling fluid circulation, with both computations and experiments. Once a new bit design has been defined according to these criteria, field tests will be done for a final validation.
This paper deals with a modelling of the turbulent flow occurring around a PDC bit. Numerical simulations have been done to study and quantify the influence of parameters such as flow rates, nozzles sizes, locations and inclinations, on the fluid behaviour. Comparisons with theory and experiments done on the same bit, including laser velocimetry data allowed us to check the accuracy of the computer code.
All these studies have revealed complex flows with various main structures such as eddies, counter currents, low circulation zones and impact points. To improve the fluid distribution along the bit and especially along the cutting edges, we have searched the most fitted design parameters which could avoid negative hydraulic structures. In that way, we are now able to design a more efficient bit.
Walk Rate Prediction on Alwyn North Field by Means of Data Analysis and 3D Computer Model
Authors: Bannerman J. S. 
Published: December 2007

ABSTRACT
This paper describes a study which was performed in order to improve the understanding of Rotary Drilling Assembly walk rates. It was based on data collected during 23 wells which were drilled from the ALWYN NORTH platform in North Sea. This platform is operated by Total Oil Marine, the British subsidiary of Total Compagnie Française des Pétroles. The ALWYN NORTH FIELD is a partnership between TOTAL (33 1/3% operator) and ELF (66 2/3%). The field location is shown in Fig 1. The study was performed within the scope of an ARTEP (Association de recherche sur les techniques d'exploitation du pétrole) research project "Maitraj".
By analyzing data from both the 17½″ and 12¼″ phases an attempt is made to explain the variation of walk rates from well to well.
A calibration of a 3 dimensional bottom hole assembly computer model (ORPHEE 3D) has been attempted and the results are presented.
Following the study the lead angle on two subsequent ALWYN NORTH wells was chosen taking into account the conclusions reached and the outcome of this is contained within the paper.
Improving Lateral and Vertical Resolution in Geotomography
Authors: Quint E. N. M. 
Published: December 2007

ABSTRACT
Well-to-well acoustics can be used to image the formation between two boreholes. In this paper we make some proposals for improving the accuracy by modification of the data acquisition and of the reconstruction. So far the resolution of the cross-well image has been limited by critically refracted signals overtaking the direct signals. We propose using three-component detection not only to separate P and S waves, but also to classify the P waves from the arriving angle. A successful classification – into direct and critically refracted rays – enables one to improve the vertical resolution of the tomographic reconstruction considerably.
Since ray-bending effects cannot be ignored, one needs a (guessed) starting model of the formation before any reconstruction can be performed. Usually a layered velocity model is chosen, which is deduced either from the travel times of horizontal rays between the two wells or from the sonic logs measured in the wells. We propose combining the sonic and horizontal ray information to come up with the optimum starting model. This model already gives a good description of the formation without any tomographic reconstruction, if the major structural variations are intersected by either one of the boreholes. The subsequent (iterative) reconstruction will average out travel-time errors and can reveal interwell structures not intersected by a borehole.
Quantitive Evaluation of Thin Bedded Reservoirs Through a "Cluster Analysis" Using High Resolution Tools
Authors: Descalzi C. , Rognoni A. , Spotti G. 
Published: December 2007

ABSTRACT
The evaluation of reservoirs in thin beds has a fundamental role in the Italian oil industry since they potentially represent one of the main gas resources. The problem is the correct evaluation, not only from the qualitative point of view, of the reservoir potential and the production horizons as well as the definition of the petrophysical characteristics as concerns volumes, mineralization and connectivity.
When evaluating very stratified lithologies (for example distal turbidites), the crux is the availability of significant log and cores, able to recognize and discretize production intervals of the order of few centimetres.
The integration of all the information available (logs, cores and well tests) and their homogenization through a "cluster analysis" algorithm, developed in order to utilize logs with a high sampling density (SHDT*), allows obtaining more realistic values concerning the petrophysical parameters.
These results lead to the re-evaluation of reserves and to an accurate estimate of the profitability of reservoirs in thin beds.
The case of an Italian reservoir composed of Pleistocenic turbidites characterized by frequent sand-shale intercalations is given as an example. The methodology was tested in this field and allowed the identification of new levels and a re-evaluation of reserves of the order of 20%.
Relating Sedimentology to Production Behaviour in Deltaic Rocks
Authors: Mijnssen F. C. J. , Weber K. J. , Floris F. J. T. , Kaasschieter E. F. 
Published: December 2007

Abstract
Averaging rock properties over grid block volumes represents a major problem in reservoir simulation studies. Often most small scale heterogeneities are ignored. To better account for common heterogeneity patterns an analogue approach is proposed using realistic models of genetic sand body types.
Because of the extensive available data, deltaic reservoirs have been selected to demonstrate this approach. A total of seven delta types is recognized containing a limited number of different genetic sand body types. These can in turn be described with only eight flow unit configurations. A study has been carried out of the fluid flow characteristics of these units with the aid of 2D simulation models. The results give a qualitative overview of the impact of various common heterogeneity patterns.
Models of this nature are thought to be very suitable for evaluating the sensitivity of simulation results to the presence of observed heterogeneities.