bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automatic Pressure Buildup Data Acquisition and Interpretation Using a Microcomputer-Based Acoustic Liquid Level Instrument
Authors: Podio A. L. , McCoy J. N. , Huddleston K. L. 
Published: December 2007

ABSTRACT
Production is lost when skin damage restricts fluid flow into the wellbore. The presence and degree of skin damage is most commonly determined through analysis of pressure buildup tests. This forms the basis for selecting wells as candidates for stimulation, workovers and recompletion. Traditionally these tests have been conducted using downhole pressure bombs or in the case of most pumping wells through the use of acoustic annular fluid level data which was processed off-site. The logistical complexities and high cost of these methods have limited the extent and frequency of well testing. Given the present need for production optimization and operating cost reduction, the development of a cost effective method for buildup testing represents a major advance in petroleum technology.
This paper describes the design, implementation and application of a microcomputer-based system for automatically performing pressure buildup tests in pumping wells, from surface measurements, and analyzing the data in realtime at the wellsite. The system is based on a portable PC which controls the operation. A solenoid-actuated acoustic source, powered with compressed gas, generates accurately repeatable acoustic pulses at variable programmable intervals. Acoustic echo travel time is interpreted in terms of position of the liquid level in the wellbore. Simultaneously the computer acquires wellhead pressure and temperature data, using high precision transducers, from which bottomhole pressure is calculated. Strip chart recordings of the acoustic signals are also made to periodically control the quality of the data. At any time during the test the operator can obtain standard graphical display of the buildup test ( Horner plot, dP vs. dT, MDH, etc. ) as well as conventional interpretation in terms of skin, afterflow rates and duration. Results from three field tests of the system are presented. They indicate that the system was used successfully in fairly harsh environmental conditions and was able to acquire buildup data of quality comparable to that obtainable with bottomhole pressure bombs. Interpretation of the results are in agreement to those obtained independently by DST.
Asphaltene Flocculation During Oil Production and Processing: A Thermodynamic Colloidal Model
Authors: Leontaritis K. J. , Mansoori G. A. 
Published: December 2007

Abstract
The need for understanding the nature of asphaltenes and asphalts and their role in the production and processing of crude oit is well recognized around the world as manifested by the current activities in the Petroleum Industry towards the exploration, drilling, production and processing of heavier oils (higher in asphaltene content). Asphaltene deposition during production and processing of oil ranks as one of the costliest technical problems the Petroleum Industry faces today. In the present report a thermodynamic-colloidal model has been developed capable of predicting the onset of flocculation of colloidal asphaltenes in oil mixtures due to either changes in composition (i.e.: solvent addition) or electrical phenomena (i.e.: streaming potential generation due to flow of asphaltenes containing oil in conduits or porous media). For oil mixtures from which flocculation is caused simply by flow, the model can make predictions as to the velocity ranges where colloidal asphaltene flocculation can be avoided. This could have a significant impact on allowed reservoir drawdown rates, well spacing, and tubing design.
Polymers for Mobility Control in CO2 Floods
Authors: Dandge D. K. , Heller J. P. 
Published: December 2007

ABSTRACT
The very low viscosity of the displacing fluid is the probable cause of much of the early breakthrough and poor areal sweep efficiency that plagues most applications of CO2 flooding technology. A focussed and already partially successful research program is described, to develop polymers that are soluble in dense CO2 and raise its viscosity sufficiently so that they can be used as direct thickeners for mobility control. Such water-free additives will offer greatly improved displacement efficiencies on both microscopic and macroscopic scales.
Developed correlations between molecular structure and solubility in both simple hydrocarbon-CO2 and in polymer-CO2 systems are reviewed. Guided by these, we have synthesized amorphous poly-1-hexenes as a first step towards the preparation of more complex multicomponent polymer systems. Reported in this paper are results on the solubilities and viscosities of various α-olefin polymers in dense lower hydrocarbons such as n-butane and n-propane, which are close to dense CO2 in many solvent properties.
Also reported are other experimental details, including the development of gas chromatographic techniques to follow the course of higher α-olefin polymerization, and measurements of molecular weights and molecular weight distribution of the synthesized polymers. It is pointed out that polymers of narrow molecular weight distribution must be used for accurate determination of solubilities in dense CO2.
The Role of Adsorption in Polymer Propagation Through Reservoir Rocks
Authors: Zaitoun A. , Kohler N. 
Published: December 2007

Abstract
Low shear injection of different-nature polymers through various sand and sandstone cores has been performed to study the specific influence of adsorption on polymer propagation and flow behavior.
As predicted by the depletion layer theory, polymer propagates faster than brine through non adsorbing porous media giving a mobility ratio less than solution viscosity ratio. An increase in clay content both decreases permeability and increases polymer adsorption. Thus a polymer propagates through pores having a smaller cross-section at a lower rate. When pore sizes become close to macromolecule size, polymer adsorbs, forming bridges in pore throats, thus giving very poor and irregular propagation rates. A dynamic method for adsorption measurements on heterogeneous rocks is proposed. Our experimental results effectively fit a capillary flow model with a crossflow section reduced by an impenetrable adsorbed layer.
Oil Price Stability: An Impossible Dream?
Authors: Kelly M. 
Published: December 2007

Abstract
With the introduction of netback deals negotiated in August 1985, the Saudis abdicated their role as the swing supplier to world oil markets. Their action ended 25 years in which first the international majors and then OPEC had held the line (officially) on crude prices at the expense of downstream margins. In 1986, oil price instability hit new highs, as sellers fought for market share in the absence of a "gatekeeper" on production and a marker crude reference price. Tranquility is not likely to be restored soon.
Stratification of Bank Energy Loans
Authors: David A. , Carson G. P. 
Published: December 2007

Abstract
Due to an increased number of problem oil and gas bank loans, the office of the Comptroller of Currency (OCC) recently revised guidelines for troubled reserve-based loans. While credit classification of oil and/or gas reserve-based loans is predicated on an assessment of all relevant credit factors, an important part of the credit worthiness is the quality of engineering data that is used to prepare an engineering report. The engineering report is addressed by the OCC with regard to "realistic" pricing and discount factors, as well as its timeliness.
Because cash flow generated from the sale of oil and/or gas in the future is the primary basis for reserve-based loan values, the OCC calculates the ratio of loan balance (Loan) to the discounted Present Worth of the future net income (PW) of proved developed producing properties as a test in determining the safety of a loan. This ratio, (Loan/PW), is defined as the Loan Ratio. According to the OCC, whenever the loan balance exceeds 65% of the discounted Present Worth of the proved producing properties, the expected cash flow cannot meet the planned amortization schedule, and the total support of the debt is provided solely by the pledged collateral, the OCC has guidelines for banks to use in classifying their problem credits. Depending on the magnitude of the undercoverage, a loan may be classified as Other Assets Especially Mentioned (OAEM), Substandard, Doubtful, or Loss.(1) Banks, in turn, are required to reserve funds for possible loss or write-off as a loss, depending on the loan classification. The reciprocal of the Loan Ratio is used by many banks and is defined as Loan Coverage, (PW/Loan). For the sake of consistency, Loan Coverage will be used in the remainder of this analysis.
Any loan write-off or loan loss reserve directly affects the profit of a bank as the amount reserved is subtracted from earnings. Creath etal(2) describe the determination of loan loss reserve and its effect on a bank's profitability. Briefly, varying magnitudes of loan loss reserves are required by the OCC when Present Worth to loan coverage (PW/Loan) drops below guideline ratios that indicate the loan's principal and interest may not be recovered. Energy banks do not intentionally make risk-oriented loans. This "no-risk" approach is the primary reason the cost of bank loans should be among the lowest available.
Application of Exploration Statistics to Venture Assessment: Potential Merits and Problem Issues
Authors: Rapoport L. A. , Grender G. C. 
Published: December 2007

ABSTRACT
Appropriate historical data on exploratory drilling and discoveries can provide valuable background information to assist in the projection of the economic outcomes of exploration ventures. This can be accomplished by using discovery statistics derived from historical data as a reference for, or supplement to, the specific assumptions made about the likelihood and size of potential discoveries in the venture under consideration.
This paper, based on an extensive body of data developed for each of the U.S. petroleum provinces, discusses the utilization of exploration statistics in the form of "discovery functions" (relations between cumulative discoveries and cumulative exploratory drilling) for the purpose of prospect or venture assessment. In particular, we illustrate the validity of these functions, and demonstrate their application to the estimation of the discovery probabilities for fields of different sizes.
However, we show that meaningful analysis requires that these probabilities be estimated separately for (suitably defined) individual depth zones. Another problem issue is that the measurement of exploratory drilling is not unequivocal: it may be defined in terms of the number of wells that are specifically targeted to, or terminating in, the zone under consideration, or in terms of both the terminating wells and those transversing the depth zone and going to deeper horizons. The effects of using these different measures of exploratory drilling in the derivation of discovery probabilities and subsequent venture assessment are outined.
Synergistic Approach for Siting and Design for Injection of Hazardous Liquid Wastes: Case Study in Western San Joaquin Valley, Kern County, California
Authors: Wilson M. J. , Kiser S. C. 
Published: December 2007

Abstract
Subsurface injection of wastes is a technology on which a great deal has been written in the last 25 years. Some of the key references are mentioned in Subsurface Wastewater Injection by Warner and Lehr (1977).
The earliest controlled waste water injection program outside of oilfield operations may have been in 1939 (Harlow, 1939 in Warner and Lehr, 1977). Its use has expanded in the last 30 years to the point that, nationally, 60% of the 15.6 billion gallons (59 million cubic meters) of hazardous waste legally disposed of in the U.S. is being injected through wells into deep aquifers (Gordon, 1984). In the past 30 years of hazardous waste injection, there has been a failure rate of only 2.4% (Morgan, 1986) where groundwater (either drinkable or non-drinkable) has been contaminated.
In California, commercial hazardous waste is transported to one of seven approved sites located around the state (Figure 1). None of the currently operating sites utilize deep well injection as a final disposition for Class I liquids. However, the geologic setting of the Great Valley in California was determined to be potentially suitable for deep-well waste injection by Repenning (1960) and Warner and Lehr (1977). The most common form of Class II liquid disposal in California is deep well injection.
Tapping the Bicameral Mind: A New Approach for Petroleum Engineering Management
Authors: Underwood E. A. 
Published: December 2007

ABSTRACT
The petroleum industry has had to curtail incoming manpower in the last few years due to a changing economic landscape. This change has made optimal use of engineering resources imperative. The optimization need not cause major upheavals within the industry. A shift in managerial thinking and a strategic integration of engineers and engineering managers into functional syndicates will aid in tapping the engineering energy and expertise present in an organization.
A Versatile, Fully Implicit, Black Oil Simulator With Variable Bubble-Point Option
Authors: Farnstrom K. L. , Ertekin T. 
Published: December 2007

ABSTRACT
A stable and efficient, general-purpose, variable bubble point black oil simulator is presented. The program utilizes the method of substitution of variables for modeling gas phase appearance and disappearance. Paralleling its application in conventional reservoir simulation, recent work has shown that the present model forms a solid basis for the development of more specialized simulators containing unique options.
The objective of this paper is to present a general description of the simulator and to describe in detail the numerical methods and specific programming techniques utilized. At the heart of the model is the variable bubble point formulation. This employs relatively complex Jacobian building routines and switching schemes. These are specially designed for efficiency and acceleration of convergence.
The automatic timestep selector for thermal simulation presented by Sammon and Rubin has been modified to accommodate the substitution of variables in black oil simulation. Techniques for implementation of this timestep selector are presented.
To solve the system of nonlinear flow equations, a modified Newton-Raphson procedure is presented. In comparison with the classical Newton-Raphson procedure, the present method requires a larger number of iterations per time step, but overall computation time is significantly reduced. A series of tests are presented to compare the classical and the modified Newton-Raphson procedures and to illustrate the efficiency and stability of the model.
A Regression Technique With Dynamic-Parameter Selection or Phase Behavior Matching
Authors: Agarwal R. , Li Y-K. , Nghiem L. 
Published: December 2007

ABSTRACT
The major problem associated with phase-behavior matching with a cubic equation of state is the selection of regression parameters. There are many parameters that can be selected as the best set of parameters, and therefore a dynamic parameter-solution scheme is desired to avoid tedious and time-consuming trial-and-error regression runs.
This paper proposes a regression technique where the most significant parameters are selected from a large set of parameters during the regression process. This reduces the regression effort considerably and alleviates the problem associated with the apriori selection of regression parameters.
The success of the technique is demonstrated by matching the experimental data for a light oil and a gas condensate.
Unsteady State Flow In Pipeline Networks
Authors: Ruehr Otto G. 
Published: December 2007

Publication Rights Reserved
This paper was prepared for the Society of Petroleum Engineers Gas Technology Symposium to be held in Omaha, Nebr. Sept. 15–16, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
This paper attacks the problem of computing transient flow in gas pipeline networks by means of finite differences and digital computation. Pressure (P) and flow (Q) are assumed to he dependent upon a single space variable (x) along the pipe and on the time (t). A greatly simplified but generally accepted mathematical model consistent, of a system of nonlinear partial differential equations is the point of departure:
Following simple changes of variable (w = p2, v = Q2), the problem is reduced to the solution of:
A stable predictor-corrector method of finite difference approximation due to Jim Douglas, Jr. and B.R. Jones, Jr. is employed to reduce the computation to the solution of a system of linear algebraic equations (matrix inversion). The incorporation of initial conditions, boundary conditions, and internal flow conservation equations, all of which in finite difference form become linear algebraic equations, results in a single matrix equation for the calculation of pressures and flows in the pipeline network.

DERIVATION OF FINITE DIFFERENCE EQUATIONS
The computation of transient flow in gas pipeline networks is complicated mathematically by the nonlinearity of the governing partial differential equations. This is in marked contrast, of course, to the situation in steady state flow, where the corresponding equations, at least in their simplest form, have exact mathematical solutions. The mathematical model we assume has resulted from a number of simplifications, including the neglect of altitude and temperature variation. Although it is beyond the scope of this note to discuss the validity and significance of these simplifications, it is generally believed that the equations we will discuss are an accurate first order description of the actual physical system.
Using Multiple Radioactive Tracers To Optimize Stimulation Designs
Authors: Williams R. L. , McCarthy J. T. 
Published: December 2007

ABSTRACT
Multiple radioactive tracers have recently been used by Santa Fe Energy to assess the effectiveness of acid and fracture stimulations. Until recently, only one radioactive tracer1, usually Iridium–192, was used and its distribution was surveyed with a conventional gamma ray logging tool. However, there are instances, such as multistage frac jobs or long interval acid stimulations, where two or more tracers would be very beneficial in assessing the effectiveness of a stimulation effort. Recent multistage fracture stimulations in the Mid-Continent using two radioactive isotopes2 allowed the operator to assess frac sand placement and vertical height growth in a single logging pass. The tools used were modified open hgle natural gamma ray spectroscopy logging systems3-6, which were originally designed to measure Potassium (K), Uranium (U) and Thorium (Th) concentrations. The energy range was expanded on the cased hole version of these tools to allow the deconvolution of individual gamma rays emitted by specific radioactive tracers. Depending upon background levels and computer software limitations, three or more tracers could be logged in a single pass.
Santa Fe Energy has used up to four isotopes in a single wellbore, Antimony–124, Scandium–46, Iridium–192, Silver–110 and Gold–198 have been placed in several conventional sand fracs, while Scandium–46, Iridium–192, Iodine–131, Antimony–124 and Silver–110 were used in a number of acid fracs to assess the stimulation efforts, using two different logging companies' cased hole tools. The data generated by these logs have allowed Santa Fe Engineers to successfully modify and improve their completion and stimulation programs. Examples of logs reflecting initial and modified frac and acid designs are provided. Procedures concerning the on-site handling of radioactive material and subsequent preparations to ensure adequate logging conditions are also presented.
An Analytical Solution for Unsteady Liquid Flow in a Reservoir With a Uniformly Fractured Zone Around the Well
Authors: Prado L. R. , Da Prat G. 
Published: December 2007

ABSTRACT
An analytical model is presented which describes the pressure behaviour of a well completed in a reservoir wherein natural fractures occur over a limited area around the wellbore. The flow in the reservoir is treated as a composite reservoir flow problem, the region adjacent to the wellbore being considered as a fractured medium and the outer region as an homogeneous one. Wellbore storage and skin effects are included in the solution, and the flow in the fractured region is mathematically described by Warren and Root's double porosity theory.
Dimensionless log-log plots of pressure vs time show the existence of several well-defined flow regimes, which can be used in the interpretation of pressure transient tests data to estimate the fractured region parameters as well as its radius around the well. This last parameter is of considerable importance for the purposes of reservoir development or infill drilling programs, for it would allow the reservoir engineer to estimate the areal extension of the fractures in the reservoir.
Based on the model results for different values of the parameters involved, guidelines are provided for conducting and interpreting a pressure test with the objective of determining the characteristics and areal extent of a natural fracture system.
Recovery Efficiency Aspects of Horizontal Well Drilling in Devonian Shale
Authors: Salamy S. P. , Saradji B. S. , Okoye C. O. , Mercer J. C. , Yost A. B. 
Published: December 2007

ABSTRACT
This study is part of the Department of Energy's Eastern Gas Shales research whose primary objective is to increase the gas reserves for the Devonian shales in the Appalachian, Illinois, and Michigan Basins. The study simulated the effect of using horizontal wells to increase the recovery efficiency of shale gas from two specific sites: Wayne County, West Virginia, where vertical well gas production has been historically high and no permeability anisotropy is thought to exist, and Meigs County, Ohio, an area with a history of moderate gas production and a calculated permeability anisotropy of approximately 8:1.
In this study, a three-dimensional, dual-porosity reservoir simulator was used to characterize the study areas after sensitivity analyses were made to determine those parameters significant in determining gas production profiles. Once the study areas were characterized, the 20-year production profile for a 2,000- foot (610-meter) horizontal well was simulated for three well locations in Wayne County and one location in Meigs County. The performances for several vertical wells were also simulated and compared with those for their corresponding horizontal wells in Wayne County. Results of the simulation showed that a horizontal well could produce seven to ten times more gas than a vertical well placed at the same location for the Wayne County site. In the Meigs County area, the study showed that permeability anisotropy is an important factor in determining the orientation that a horizontal well should be drilled. Furthermore, the study concluded that horizontal wells are more efficient than vertical wells in producing Devonian shale gas from a fixed volume of rock.