bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overview of Gelled Polymer Projects Conducted in Central Kansas
Authors: Jack L. M. , Schoeling L. G. , Green D. W. 
Published: December 2007

Abstract
Crosslinked polymer treatments are being implemented on both the injection and production - side in central Kansas to increase oil production and reduce water-oil ratios. In the past few years, Murfin Drilling Company has utilized these gel treatments and have had both successes and failures. This paper presents the results of two injection-side projects in the Lansing-Kansas City formation and four producing-side treatments in the Arbuckle formation from an independent oil operator's point of view.
The Lansing-Kansas City formation is a sequence of limestone reservoirs separated by shales. When these reservoirs are simultaneously waterflooded, usually the highest permeability zone takes the majority of the brine, causing poor sweep efficiency in the waterflood. Injection of gelled polymers can plug these high permeability zones thus increasing the waterflood sweep efficiency. Results from two projects in Decatur and Graham Counties will be discussed.
The Arbuckle formation is typically a dolimitic limestone reservoir underlain by bottom water. Water coning usually occurs due to gradients in flow potential established around the wellbore by oil production. If vertical permeability exists, this difference in flow potential causes mobile water to flow into the wellbore. Gelled polymer treatments can reduce the permeability to this mobile water, thus reducing the producing water-oil ratio. Typically, a sharp decrease in WOR is noted immediately following a treatment. This decrease is followed by an increasing WOR as the oil production gradually resumes its normal decline. Four treatments conducted in Ellis, Graham, and Rooks Counties will be discussed.
A Further Stability Analysis for the ADI Procedure as Applied to Singular Matrices
Authors: Taylor Howard L. 
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Abstract
Solving =, by numerical techniques requires application of ADI procedures to singular matrices which leads to numerical instability for small values of the ADI parameter w.
A study of this problem demonstrates that restriction of IRml/w (where Rm is the largest residual) will control these instabilities. Applications to compressible and incompressible Darcy flow are discussed.

Introduction
The equations of reservoir flow commonly have the following form V (KVP) Q where in two dimensions,
..........................................(1)
The ADI (or Peaceman-Rachford) procedure is one of the methods frequently used to solve the associated difference equations. In our mathematical discussion we will write these difference equations approximating the above differential equation In matrix notation as Au = q where u is a vector representing pressure or potential at node points, q is a vector of production rates and points, q is a vector of production rates and A is the matrix of coefficients which depend on the permeabilities or mobilities.
In using this procedure numerical instabilities often occur for small values of the parameter w,, particularly for incompressible parameter w,, particularly for incompressible flow with no-flow boundaries. These instabilities have been observed often and techniques to avoid them have been suggested. In this paper we will consider the mathematical and computational origin of these instabilities. This study will allow us to suggest improved methods of handling such problems and will give us a better understanding of the roll of the parameter w in the iteration process. process.

MATRIX DESCRIPTION OF THE ADI PROCEDURE
Consider three symmetric semi-definite n × n matrices A, H, and V such that
..........................................(2)
Let D be a symmetric, positive definite normalizing matrix, q a given vector, Uo an arbitrary initial vector, and w-a number for any positive integer k. Then the ADI procedure can be defined by procedure can be defined by ..........................................(3)
and
..........................................(4)
Here the vectors will approximate a solution to the equation
..........................................(5)
Combination of Numerical and Analytical Techniques To Improve Waterflood Model Efficiency
Authors: Roper William A. , Merchant Jack E. , Duvall Carolyn A. 
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Abstract
Description of flow near wells is difficult when modeling steady-state flow in an oil reservoir. A technique is presented which avoids this difficulty by describing pressure and velocity in part numerically and in part analytically.

Introduction
Numerous mathematical models have been developed to predict water-flood recovery. Often a steady-state or semisteady-state model will yield adequate predictions. The method described predictions. The method described herein is the basis of an improved steady-state reservoir model.
A frequent numerical approach is to represent the reservoir by a grid network and to determine the steady-state pressure distribution by relaxation. pressure distribution by relaxation. The principle weakness of this method is that a rectangular grid is poorly suited to represent the pressure distribution around wells. Flow near wells is radially symmetrical and rapidly changing. Flow in a grid network is assumed to occur only along grid lines. Figure 1 depicts the difficulty of representing flow near a source by a grid network. For this reason most numerical models require a large number of grid points to adequately describe flow.
The method presented here utilizes pressure distribution and flow pressure distribution and flow velocities which are in part analytical. In essence, the point sources and sink are subtracted from the original flow problem, leaving a modified flow problem, leaving a modified flow problem with distributed sources and sinks. problem with distributed sources and sinks. The modified flow problem can then be solved numerically with less difficulty than the original flow problem.

DEVELOPMENT
The mathematical analog to steady state flow in a reservoir is based on Darcy's Law and the conservation equation. If the three-dimensional physical system is reduced to a two-physical system is reduced to a two-dimensional model, and if other simplifying assumptions are made, flow in a reservoir can be related to the solution of the following equations.
A Study of the Effects of Bit Gauge Length and Stabilizer Placement on the Build and Drop Tendencies of PDC Bits
Authors: O’Bryan P. L. , Huston C. W. 
Published: December 2007

Abstract
This paper presents field data that indicates the gauge on Polycrystalline Diamond Compact (PDC) bits may act as a near bit stabilizer. When used with a pendulum bottomhole assembly (BHA) having stabilizers placed at 60 and 90 feet above the bit, the BHA can have the tendencies of a building assembly.
Field observations were verified by computer simulation using a two-dimensional static BHA model providing a predictive method for BHA analysis when using PDC bits. The results of a sensitivity analysis using the computer model are presented and will provide guidelines for stabilizer placement when using PDC bits in straight hole drilling applications. Included in the analysis will be the effects of PDC bit gauge length, wellbore inclination, drill collar stiffness, and hole diameter on the build and drop tendencies of pendulum BHA's when used with PDC bits as a function of weight on bit (WOB).
Experimental and Modeling Studies of Asphaltene Equilibria for a Reservoir Under CO2 Injection
Authors: Novosad Z. , Costain T. G. 
Published: December 2007

ABSTRACT
An experimental and numerical modeling program was undertaken to evaluate stability of asphaltenes in a 29°API gravity reservoir undergoing tertiary CO2 injection. The study aimed to develop a better understanding of asphaltic solids formation and possible ways of controlling it.
Asphaltene phase behaviour and the extent of asphaltene precipitation in live oil were investigated for a range of pressures and temperatures, in presence of CO2 and normal alkanes as precipitants. The nature of the solids formed was also studied using a variety of techniques. A molecular thermodynamic model with asphaltene-asphaltene and asphaltene-resin association was used to correlate the asphaltene precipitation data. The model not only matched the trends in asphaltene behaviour, but did so to a degree quantitatively.
The thermodynamic model calculations provided valuable insight into the behaviour of this complex system Destabilization of asphaltenes by CO2, the degree of which varied with system pressure and temperature, can be shown to be related to specific changes in the properties of the liquid (oil) phase, brought about by changes in system composition, pressure, and temperature. In agreement with observations in a recently completed CO2 flood pilot project, the model indicated asphaltene destabilization along the entire wellbore under the conditions prevailing in the pilot producing wells. The tuned asphaltene model allowed examination of asphaltene stability under a variety of wellbore conditions and gave indication of operating scenarios that should be avoided in a field project to minimize the solids formation.
The predictive capabilities of the model are critically evaluated in view of scarcity of reliable data on asphaltene properties and in-situ structure.
Reservoir Characterization by Seismic Classification Maps
Authors: Sonneland L. , Barkved O. , Hagenes O. 
Published: December 2007

Abstract
In a recent paper we introduced the seismic classifier concept. We have demonstrated how classifiers can help us to identify particular facets of the subsurface "architecture" and how they combine the structural interpretation and the 3D seismic data in a very compact way. Through classifiers like reflection intensity, acoustic impedance contrast and reflection hetereogenity indicator the interpreter can in a quantitative sense discriminate between properties relevant for his particular problem.
We will extend our classifier-family further and point out how the "resolution" in our data-set effect the construction of these new classifier maps. Interpretations based on classifier-maps require new functionality in the application software. Based on examples from case studies we will identify these requirements and apply them. Of particular relevance is when the projections of the geological model onto the classifier map can be revealed. Then these maps can indicate the paleogeographical scene.
Finally we will present some results from our efforts in compressing even more information into the classifier display. Among these are some 3D graphics displays where the classifier variations are distributed along a topographical surface. The objective here is to improve the interpreter's ability to comprehend the vast information volume he is dealing with, through meaningful graphics.
Naturally Occurring Radioactive Material Logging
Authors: Carroll J. F. , Scott H. D. , Gunn R. A. , O'Brien M. S. 
Published: December 2007

ABSTRACT
The phenomenon of scaling in both downhole and surface production equipment is well knownwhere water-drive reservoirs are in production. Sulfate scales, consisting mainly of barium,strontium, and calcium, occur on surface and downhole equipment. Traces of radium may be present in such scales, making them radioactive. Removal and cleaning of such scaled equipment for later use can present a potential health hazard. Alternatively, the equipment may have to be removed, stored, and disposed of according to established procedures for low-level radioactive waste.
Measurement of radiation levels at the wellsite requires the use of rugged gamma ray survey meters by specially trained personnel. Measurement of low levels of radiation on individual tubing sections can be difficult in the presence of natural background radiation. However,gamma ray well logging tools are very sensitive instruments and can make radiation measurements inside scaled tubing in the well with less sensitivity to background signal.
To evaluate scale radioactivity before removing the tubing from the well, a reconnaissance logging technique has been developed that uses a gamma ray logging tool calibrated specifically for radium. This new technique allows better decisions to be made prior to removing the tubing.
In this paper, procedures used to calibrate the logging tool are described, together withmeasurements made to correct for the effect of tubing wall thickness. Field examples are presented where this technique has been successfully applied.
Reasons for Differences in Recovery Efficiency
Authors: Arps J.J. 
Published: December 2007

Introduction
The recovery efficiency or the percentage of stock-tank oil in place in the reservoir recoverable by natural expulsion mechanisms is known to vary over a wide range. Under the most favorable conditions recovery efficiencies as high as 85 percent to 90 percent of the oil in place have been repower At the other end of the scale recoveries as low as 10 percent of the oil in place have been experienced. The principal reason for such differences is in the displacement mechanism itself specifically whether the oil is displaced by invading water (water drive), by the expanding gas coming out of solution (solution gas drive) or by an expanding gas cap, or by gravity segregation.
This paper is a continuation of the study, made by the API subcommittee on recovery efficiency, which culminated in Nov., 1967, with the publication of API Bulletin D14, "A Statistical Analysis of Recovery Efficiency". For this study the sub-committee used case histories on some 312 producing oil reservoirs from which certain empirical relationships were derived by regression analysis. For the water-drive cases the following regression., equation for the recovery efficiency was found:
..........................................(1)
The basic data used for this equation came almost exclusively from sand and sandstone reservoirs. A comparison of the observed and computed values of the recovery factor for 70 water drive reservoirs is reproduced here as Fig. 1.
For the reservoirs under a solution-gas-drive mechanism the subcommittee established for the recovery efficiency below the bubble point the following regression equation:
..........................................(2)
The basic data used for this equation came from a variety of rock types, including carbonate rocks. A comparison of observed and computed values of the recovery factors from the 80 solution-gas-drive reservoirs below bubble point used in this study is shown as Fig. 2. For the units and nomenclature, reference may be made to the list of symbols at the end of this paper.
The cumulative distribution of the recovery efficiencies for four drive mechanisms as determined by this same subcommittee study is shown here as on the log-normal graph of Fig. 3. It may be noted that the recovery efficiencies both for water drive and for solution-gas drive below the bubble point follow a typical log-normal distribution as indicated by their straight-line trends on these charts.
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New Techniques and Quality Control Find Success in Enhancing Productivity and Minimizing Proppant Flowback
Authors: Ely J. W. , Arnold W. T. , Holditch S. A. 
Published: December 2007

ABSTRACT
Hydraulic fracturing has yielded successful stimulation results in hydrocarbon producing reservoirs for over 40 years. In certain reservoirs, however, hydraulic fracturing does not always achieve the desired results. In some cases, due to excess production of proppant or excess water production, the fracture treatment can cause operating problems. A paper published by Robinson et al.1 discussed the merits of flowing back a well on a small choke to minimize the closure stress on the proppant. In that paper, a recommendation was made to monitor the tubing pressures after the fracture treatment, and if closure times appear to be excessive, then one should initiate a low rate flowback of the fracture fluid to assist fracture closure.
Approximately 4 years ago, the initial treatment designed to use the "forced closure" technique was conducted on a Canyon Sand well in west Texas. The fracture treatment was successful, but the most surprising aspect of the procedure was that significantly less proppant was produced after the treatment when compared to other wells in the area. In the last few years, the forced closure technique has been used on several hundred wells in many different geologic horizons.
The forced closure technique, alone, may not be the reason for success. However, the use of forced closure combined with the use of aggressive proppant scheduling and the application of "intense quality control" can lead to dramatic improvements in stimulation success. Intense quality control involves field testing of fracturing fluids at reservoir temperature prior to pumping operations.2 In this paper, field results have been included to illustrate how the forced closure technique, coupled with high proppant concentrations and intense quality control, can significantly increase the productivity of low permeability oil and gas wells.
Three-Dimensional Well Model Pre-Processors for Reservoir Simulation With Horizontal and Curved Inclined Wells
Authors: Morita N. , Singh S. P. , Chen H. S. , Whitfill D. L. 
Published: December 2007

ABSTRACT
This paper presents 3-D pre-processors to calculate proper well inflow relations for modeling horizontal or curved inclined wells in a finite difference reservoir simulator.
The technique frequently used in the oil industry is Peaceman’s analytical well model although several assumptions are violated in the case of a horizontal well. An error analysis was conducted for the well model proposed by Peaceman. Based upon this analysis, new methods are proposed to improve the accuracy of modeling horizontal and curved inclined wells.
The Concept of Critical Rate in Gas Coning and Its Use in Production Forecasting
Authors: Konieczek J. 
Published: December 2007

Abstract
Published critical rate formulae for steady state oil production from beneath a gascap pose difficulties when used to forecast well performance in practical situations. In this paper the dynamic deformation of the gas/oil contact is described based on the Dupuit-Forchheimer potential. By semi-analytical methods the production performance is derived for a horizontal oil well in a 2 phase system, chosen because of its simple geometry and because such wells are of recent interest.
The solutions distinguish two transient periods, before and after gas breakthrough. These demonstrate that the oil potential is initially constrained only by the vertical lift capacity, but declines after gas breakthrough in proportion to the inverse of the cumulative production. Typical for a horizontal well, some 20-30% of movable oil is produced under transient conditions. The decline changes again during the semi-steady-state period when the drainage area limits begin to have an effect.
The results are presented by dimensionless decline type-curves for various well spacings and well elevations.
Market Potential Of Deep Delaware Basin Gas Reserves
Authors: Bulla C.J. 
Published: December 2007

Abstract
The natural gas industry has had a unique and exciting growth record since the inception of the high pressure long distance pipelines in the early 1930's.
From a very limited requirement for natural gas in 1930 the total United States market has grown steadily, until in 1966 we produced and consumed slightly less than eighteen trillion cubic feet of gas. But is this the end? Is it true, as some have speculated, that the majority of the future energy requirements in this country will be satisfied not by natural gas but by nuclear energy, electricity, solar energy or other presently unknown sources of potential energy?
The Future Requirements Committee, a group made up of transmission and distribution company executives, believes otherwise. They have predicted that by 1975 the energy market in the United States will require 25.5 trillion cubic feet of natural gas per year, and by 1990 this requirement will increase to 36.0 trillion cubic feet per year. In cumulative figures this means that from the end of 1967 through 1990 the natural gas industry must discover and produce over 625 trillion cubic feet of natural gas if it is to serve this total requirement.
With the very large marketing area of the inter and intra-state transmission pipelines presently taking gas from the Permian Basin and the interest of other major pipelines in Permian Basin gas reserves it might appear that the market potential of deep Delaware Basin reserves is rather academic. Perhaps the real question should be, can the Deep Delaware Basin supply all of the gas reserves which will be demanded of it?
Know-How of Superdeep Drilling in the GDR
Authors: Kraus W. , Geisler H. J. , Heyne B. , Mohrmann R. 
Published: December 2007

Abstract
The paper describes conditions, features experience and practical knowledge of deep-hole drilling in the German Democratic Republic taking as an example borehole Schwerin-1.
The characteristics of Zechstein formation have a determining influence on planning and executing drilling operations. They affect to a high degree the well location, the casing, mud and cementing program, as well as complications encountered during drilling.
Thanks to the drilling of superdeep and a lot of deep holes GDR experts have ready-to-use know-how in all fields of deep-hole drilling.
Relief Well Breakthrough at Problem Well 2/4-14 In the North Sea
Authors: Aadnoy B. S. , Bakoy P. 
Published: December 2007

Abstract
After being out of control for a year, an underground blowout in well 2/4-14 in the North sea was successfully killed through a relief well. This paper covers mainly the breakthrough phase. A theory for relief well breakthrough is also presented along with the field case.
Effective Well Test Interpretation and Early Reservoir Simulation Help To Optimize Rotliegend Gas Reservoir Development
Authors: Andreae H. H. , Schalow G. 
Published: December 2007

Abstract
The sandstones of the Rotliegend formation are found throughout northwestern Germany as thick Permian deposits underlying permian evaporites. They are a large potential for Germany's present and future gas production. The reservoirs are located at depths of 4,500 to 5,000 m. Average reservoir thickness is between 10 and 150 m. Average porosities range between 10 and 18% and permeabilities between a few microdarcies and 1000 millidarcies.
The paper deals with reservoir evaluation in the Westerholz field, where three wells have produced gas from the Wustrow sandstone of the Rotliegendes for three years. It discusses the combined use of pressure transient interpretation, RFT pressure profiles, and production/interference test analysis.