bluuebunny/crossref_metadata_2025_split huggingface dataset:
Percolation Theory of Foam in Porous Media
Authors: Chou S. I. 
Published: December 2007

Abstract
A statistical network model and percolation theory are presented to describe the behavior of foam in porous media. Central to the present theory are constrained pore throat and pore body size distribution functions which characterize the converging/diverging nature of the pore geometry and the assumption that foam lamellae are generated by snap-off in pores with an aspect ratio greater than some critical value. Foam lamellae are not always stable; they may break-and-remake. Permeability reduction results from blockage of the flow channels. The probability of snap-off and the percolating conductivity of the network are calculated, approximated by a Bethe tree, which relates to two-phase permeabilities.
Results show that foam generation critically depends on the pore size distributions and that a strong foam could be generated by the snap-off mechanism, provided that the average pore aspect ratio is sufficiently large. Consistent with experimental observations, the theory predicts that gas relative permeability is greatly decreased by foam and approaches zero at the trapped gas saturation corresponding to the minimum gas saturation below which the gas channels become discontinuous. Because snap-off occurs only in gas-occupied pores, the water relative permeability is not affected by foam. Thus, the theory is able to describe quantitatively gas and water relative permeabilities with or without foam.
The predicted relative permeabilities together with Darcy's law of two-phase flow explain much of the anomalous behaviors of foam in porous media, including the near-constancy of steady state saturation in the presence of a strong foam and the seemingly contradictory effects of gas and liquid flow rates on foam. The possibility of foam generation by imbibition and the effects of rock permeability, wettability, and the presence of residual oil on foam displacements are also discussed.
Results and Difficulties of the World's Largest In-Situ Combustion Process: Suplacu de Barcau Field, Romania
Authors: Carcoana A. 
Published: December 2007

Abstract
The Suplacu de Barcau oil reservoir, a monocline with 5° average dip north and located in the northwestern part of Romania, is a shallow unconsolidated sand with high porosity and permeability and with 295 MM bbls (46.9 × 106sm3) of 2000 cp original oil in place. After a pilot test was initiated up the structure in 1964 the inverted five-spot combustion pattern was expanded and gradually replaced by a line of injection wells.
The actual five miles long in-situ combustion front is moving down dip being sustained by injecting 120 MM scf/day (3.36 × 10 sm3/day) into 100 injection wells. The balance is maintained by the oil, water, combustion gases and nitrogen produced through 600 wells influenced by combustion.
The burning front advancing down structure is followed by the line of injection wells, transferring the air injection to the producers exceeded by the front.
The difficulties encountered are related with mud and steam volcanos appearing high structurally in isolated areas, and with the evacuation of large volumes of combustion gas sometimes containing CO. Also the presence of hazardous gas in the basement of some village houses which overlap the combustion zone is threatening the area. Remedial work is needed also to overcome other difficulties such as injectivity reduction, rebel emulsions, excessive heating of some of the producers, and failure to avoid the back pressure which inhibits flow from the formation into the producer's well bores.
Injection/Production Monitoring: An Effective Method for Reservoir Characterization
Authors: Honarpour M. M. , Tomutsa L. 
Published: December 2007

ABSTRACT
Geological heterogeneities controlling fluid flow paths in the Department of Energy Tertiary Incentive Project (TIP) area in Unit ‘A’ of Bell Creek (MT) field were identified and described using injection, production, pressure, pressure falloff, and pulse test data. Monthly injection rate and pressure data, over a period of 10 years of linedrive waterflooding followed by 6 years of 20-acre, five-spot, water and micellar-polymer injection, were analyzed using the Hall plot method. Water production front tracking and mathematical simulation results were integrated with information obtained from geological analysis and provided an improved interwell formation characterization. This integrative approach provided information about interwell reservoir properties such as directional transmissivities, fluid flow patterns, residual oil saturation, degree of continuity, presence of flow barriers, and permeability conduits.
In the TIP area, analysis of the injection data with the Hall method provided distinct directional formation transmissivity for the preflush, micellar, and polymer stages of injection. Analyses of pressure-pulse and falloff tests conducted before the application of the chemical flood provided a baseline for comparing directional flow characteristics. The influence of various geological heterogeneities such as faults/permeability variations on fluid flow characteristics of the reservoir at various stages of linedrive waterflooding and chemical flooding was identified. The results show good agreement with any complement information obtained from geological, petrophysical, and petrographical analyses. They also indicate that the effects of micellar and polymer adsorption/retention on fluid flow charcteristies of a reservoir can be quantified using the Hall plot method.
Analyzing injection-production-pressure data and front monitoring during waterflooding proved to be an effective method for characterizing candidate reservoirs for enhanced recovery and for monitoring their performance in a continuous manner.
Capillary Number Relations for Some North Sea Reservoir Sandstones
Authors: Garnes J. M. , Mathisen A. M. , Scheie A. , Skauge A. 
Published: December 2007

ABSTRACT
The paper summarizes measurements of capillary desaturation curves for some North Sea sandstone reservoirs, which are candidates for enhanced oil recovery processes. The capillary number, Nc, is altered both by increase of the viscous forces and by reduction of the capillary forces (lowering of interfacial tension). The capillary desaturation curves, CDC, are compared to the pore size distribution, XRD, liquid permeability, and dispersion coefficient, measured on the same core material. The critical capillary number and the shape of the CDC are interpreted by dispersion/capacitance effects, pore size distribution and wettability, and are found to correlate to both the dispersivity and the permeability of the cores.
Cores drilled with oil based mud showed only minor change in oil saturation, when the capillary number were increased. While cores drilled with water based mud gave a normal decrease in oil saturation at high Nc. After applying a multi-step cleaning procedure, the CDC was in agreement with results from water based cores from the same formation. The capillary desaturation data is compared to results of sandstones from other areas, showing that some North Sea sandstones are good candidates for enhanced oil recovery processes based on lowering of the interfacial tensions.
A Flue Gas Huff ‘n’ Puff Process for Oil Recovery From Shallow Formations
Authors: Johnson H. R. , Schmidt L. D. , Thrash L. D. 
Published: December 2007

ABSTRACT
Troutman Oil Co., Inc. of LaCygne, Kansas has developed a low-cost process for recovery of oil from shallow oil formations. The process (named "TWINC02") relies on immiscible displacement of oil through the injection of flue gas in a cyclic injection program. It was first installed in the LaCygne-Cadmus field located in Linn County, Kansas. The project has been in continuous use since 1979. Oil production rates have stabilized and the project has proven to be cost-effective given its small investment requirements and low operating costs.
Flue gas is generated by burning natural gas in an internal combustion engine. The exhaust gas is treated and is compressed to around 250 psi for injection into the reservoir. Following injection, the same well is converted to production and the well flows oil, water, and gas into surface separating units.
The economics associated with this oil recovery process as reported in the paper have been updated to reflect 1989 prices and conditions.
This analysis assumes that the oil producing wells and related oil production infrastructure are in place. The analyzed project area contained 51 wells in 225 acres. Incremental cost to install a system in 1989 similar in scale to that employed by Troutman Oil is estimated to be approximately $100,000. For the Troutman Oil scale of operations, the operating costs are estimated at $37,400 per year.
Cash flow and profitability depend on the level of oil production, posted prices, and net revenue interest in a lease. For example, at a posted price of $20 per barrel and average oil production of 15 barrels per day, the annual cash flow from the entire project is estimated at $43,000 assuming an 80 percent net revenue interest. This level of cash flow will payback the initial investment in 2.3 years (undiscounted) and yields an internal rate of return of 42 percent over a 10 year project life. Economic parameters are presented in this report which will enable the reader to estimate the economics associated with application of the process at a particular property, including the minimum oil production required to cover operating costs and repay the initial capital investment.
Waterflooding the Minnelusa With Aluminum Citrate Gelled Polymer, Powder River Basin, Wyoming
Authors: King W. A. 
Published: December 2007

Abstract
Because of their high permeability variation and high viscosity ratio, Minnelusa formation waterfloods have been polymer/flooded for many years. The application has been documented numerous times.
To increase polymer viscosity insitu, alternate injections of aluminum citrate and polymer were begun in the mid 1970's. The results were difficult to document and the probability of efficient insitu mixing and, therefore, efficient insitu gellation was questioned.
The problem of efficient mixing was solved in the mid-1980's when aluminum citrate was mixed with polymer on the surface just prior to injection. Gellation would occur underground. The continuous surface mixing of polymer with aluminum citrate has become standard practice in the Powder River Basins Minnelusa waterfloods.
Use of Computer Graphics in Large-Scale Reservoir Simulation
Authors: Huang A. Y. , Ziauddin Z. 
Published: December 2007

ABSTRACT
Development of a reservoir simulation model involves collection and analysis of an enormous amount of reservoir and well data for initial input. Computer graphics is the most effective tool for geologists and engineers to visualize, verify, and analyze the input data. After each simulation run, simulation engineers then have to depend heavily on computer graphics to analyze an even more intimidating amount of simulation results data. This is especially true at Saudi Aramco because of the large simulation models used to simulate the world's largest hydrocarbon reservoirs.
Saudi Aramco's EXPEC Computer Center supports a wide spectrum of computer graphics applications to aid the exploration and engineering staffs through the entire cycle of reservoir characterization. The graphics applications help during the pre-simulation model data analysis as well as in the post-simulation results analysis.
Larger and more accurate simulation models are currently being developed In Saudi Aramco. Computer technology (both software and hardware) needs to advance continually such that computer graphics can be utilized as an effective and efficient engineering tool by reservoir simulation professionals.
This paper addresses Saudi Aramco's experience in dealing with very large simulation models and using computer graphics as an engineering tool. The program efficiency, device dependence, and data management problems will be discussed. The computer speed, data storage and access methods, data transmission speed, and graphics devices will also be detailed.
Criteria for Professional Engineering Microcomputer Software Human Interfaces
Authors: McCreary J. G. 
Published: December 2007

ABSTRACT
To be fully effective, engineering software must be easy to learn and easy to use for the casual first time user, as well as powerful enough to satisfy the experienced power user. The "human interface" represents how the user and the software communicate via keyboard, mouse, digitizer, screen, plotter, and printer. Better human interfaces make the software less mysterious and easier to use and improve the quality of the output but at the cost of more programming time.
The term "user friendly" is much over used without ever being defined. The more recent term "robust" has not provided better definition. Every individual or organization has at least a subconscious definition of these terms and has formed an opinion of the minimum acceptable level of software human interface. Whether developing or buying software, it is necessary to establish firm criteria of exactly what is the minimum acceptable. In addition, thought must be directed toward the optimum human interface balancing features that are "nice to have" against development cost.
This paper suggests a reasonable balance between the hypothetical ultimate human interface and the cost of development.
Coiled Tubing Workovers in Deep, Hot Wells
Authors: Mirza T. , Budiman M. , Cannan W. L. , Bordelon T. P. 
Published: December 2007

ABSTRACT
Mobil Oil Indonesia Inc. has successfully utilized a 1-1/2" OD coiled tubing unit in a well workover to isolate the upper portion of the producing zone. This isolation is necessary to produce gas, richer in condensate, from the lower producing zone. It was proved that the coiled tubing unit was able to perform squeeze cementing and drilling out of same at a depth of 10,000 ft and bottom hole temperature (BHT) of 350 °F.
Ottawa sand was pumped to temporarily block the lower zone. A 3-3/8" down hole drilling motor with a 4-1/2" flat bottom mill was used to drill out cement.
The cost of the workover using the coiled tubing unit was approximately US $ 400,000. Had a conventional drilling or workover rig been used, the workover cost would have been significantly higher. Furthermore, this operation requires less well shut down time as the wellhead and flowlines do not need to be dismantled for the workover.
One Arun Field gas well has been worked over with this technique. Before the workover, the well produced with a condensate to gas ratio (CGR) of 34 bbl/MMSCF. Post workover results indicate that the well is currently producing with a CGR of 60 bbl/MMSCF.
There were some problems in the first job associated with the high temperature of the reservoir. These problems have been overcome which will result in lower workover costs on subsequent jobs.
The Effect of Surface and Downhole Boundary Conditions on the Vibration of Drillstrings
Authors: Clayer F. , Vandiver J. K. , Lee H. Y. 
Published: December 2007

ABSTRACT
Surface and downhole boundary conditions are identified for a typical drill string using a 17.5 inch tri-cone bit. A case study is presented using surface vibration data acquired in production drilling operations in southern France. The data presented include high bandwidth force, torque and acceleration measurements, made on the surface with an instrumented sub. The sub was inserted in the drill string just below the power swivel The results include direct impedance measurements of the drilling rig in torsional and axial motion. Comparisons are made between simulated and measured impedance functions. The results also include estimates of the boundary condition at the bit in torsional and axial motion. Surface measurements are compared to simulated transfer function models of the entire drill string for torsional and axial vibration. A relative displacement source is introduced as a realistic model of the action of a tri-cone bit.
Materials Assessment for Sour Service Applications
Authors: Kermani M. B. , MacCuish R. G. 
Published: December 2007

ABSTRACT
In detecting the susceptibility of tubular goods to sulphide stress cracking (SSC), a novel, easy and reproducible approach has been established, offering prediction of long term exposure behaviour. Two techniques have been used to evaluate the SSC behaviour of materials by placing the emphasis on FAILURE PREDICTION. These include constant extension rate tensile (CERT) testing and the use of a fracture mechanics approach. The former method provides an efficient and rapid method of ranking of materials based on normalised strain to failure. The latter has been employed to identify threshold stress intensity factor (KIscc) below which the material can be used safely and confidently. The approach adopted incorporates both techniques combining the ease of CERT testing with the accuracy of fracture mechanics, on the basis of which fitness for purpose evaluation of tubular goods have been carried out.
The results have led to a better definition of operational limits of tubular goods for sour service applications over a wide range of testing conditions. This has enabled the selection of the most suitable/cost effective material for specific use. The environmental variables studied include solution chemistry, the pH, testing temperature and hydrogen sulphide partial pressure.
A Study to Determine the Effect of Damping on Finite-Element-Based, Forced-Frequency-Response Models for Bottomhole Assembly Vibration Analysis
Authors: Apostal M. C. , Haduch G. A. , Williams J. B. 
Published: December 2007

ABSTRACT
A computer based model for avoiding and characterizing dynamically induced drill string failures is presented. This model is applicable in both a planning and a real time mode of operation. The finite element model used in this study is designed to account for the forced frequency response of a Bottom Hole Assembly (BHA) drilling in an arbitrary curved three-dimensional wellbore. As a consequence of the greater simplicity of the resulting dynamic finite element model, it is standard operating procedure in drilling mechanics to exclude the effects of damping when carrying out a forced frequency response (FFR) vibrational failure analysis of a drilling BHA. Since damping, due to the presence of fluid, formation, friction and other effects, is the real world situation, the authors undertook the work described in this paper in order to determine the nature and the magnitude of the influence which damping exerts on drilling BHA's and their associated critical failure modes.
The FFR analysis model presented herein enables a user to determine the forced frequency response (critical speeds) of a BHA due to imposed load and/or displacement excitations anywhere in the drill string. The FFR solution is computed about the displaced static configuration, which means that the Jacobian (i.e. stiffness) matrix contains the effects of contact, stress stiffening and friction. The mathematical formulation of the FFR solution algorithm has been developed in such a way as to admit damping in the steady-state response behavior. An important implication of damping is that while the response of the BHA will be at the same frequency as the excitation, it need not be in phase with it. A major benefit of this model is that it provides a mechanism to evaluate the effect of including (or neglecting) damping in conventional BHA FFR finite element analysis.
With regard to the above described study, this paper first reviews the theoretical basis for the FFR model utilized and follows with a presentation of field data case studies. These studies validate the utility of employing the model to predict (and therefore avoid) critical rotating speeds and also demonstrate the significant role which damping plays in obtaining useful real world results from FFR finite element analysis. In this regard, the effects of both uniform and frequency dependent damping upon critical operating speed ranges and response magnitudes are examined.
Openhole Drilling Using Coiled Tubing and a Positive Displacement Mud Motor
Authors: Fultz J. D. , Pittard F. J. 
Published: December 2007

ABSTRACT
An investigation into the feasibility of drilling openhole with coiled tubing indicates that such operations are feasible using currently-avaliable technology. The study covers aspects of the drilling operation, including bottomhole equipment, surface equipment, coiled tubing unit, drilling logistics and cost. The conclusion is made that coiled tubing drilling operations can provide benefits in terms of safety, formation damage and economics.
Education and Professionalism for the 90's
Authors: Curtis L. B 
Published: December 2007

ABSTRACT
Engineering education, and the professionals it produces, will continue to be subject to many changes and pressures through the 1990's. Their performance will be viewed from the perspectives of society and the many institutions that function within its framework. Technology will continue to change in the petroleum industry in response to its needs, and the pressures placed on it from other quarters.
Use of a Multifractal Approach for Multiphase Flow in Heterogeneous Porous Media: Comparison with CT-Scanning Experiment
Authors: Lenormand R. , Kalaydjian F. , Bieber M-T. , Lombard J-M. 
Published: December 2007

ABSTRACT
This paper depicts an original model for the description of heterogeneous media, based on fractal and multifractal geometries.
Rather than using, as in Hewett's fractal approach, a random noise to generate heterogeneous patterns, we have developed an approach much closer to geostatistics and based on multifractal approach. Multifractal is a characterization of spatial distribution of a continuous variable, such as permeability or porosity. The construction rule is based on a multiplicative process which gives a multifractal square structure with the size 2n × 2n. The main property of such a construction is the correlations it gives at all length scales.
This method is then modified to generate anisotropies in the x and y directions by using rectangular rather than square multifractal blocks.
A wide variety of patterns is obtained by tuning only two dimensionless correlation lengths. Consequently, any pattern can be located on a 2D diagram with the extreme cases being the homogeneous medium, the horizontal and vertical layering, and the multifractal.
Two-phase displacement patterns are obtained by a network flow simulator coupled to this anisotropic multifractal generator. The results are in good agreement with experimental patterns obtained by CT-Scanning during gas injection in layered Berea sandstone.
The model contains the main features of the rock sample, which play a role in immiscible displacements, such as randomness, all ranges of correlations and anisotropy.
Microbial Enhanced Oil Recovery: Interfacial Tension and Gas-Induced Relative Permeability Effects
Authors: Chisholm J. L. , Kashikar S. V. , Knapp R. M. , Mclnerney M. J. , Menzie D. E. , Silfanus N. J. 
Published: December 2007

ABSTRACT
Potential mechanisms involved in microbial enhanced oil recovery (MEOR) from sandstone reservoirs are reviewed. Three phase relative permeability studies have shown that residual oil saturation can be reduced by the presence of gas in a water wet system. The production of biogenic gas to create a free gas phase can account for incremental oil recovery in MEOR processes.
Reduction in interfacial tension between formation fluids can be caused by metabolic products. Also, bacterial plugging appears to preferentially occur in larger, high permeability pores. As this occurs fluid is diverted into smaller pores causing an increase in fluid velocity within them. The changes in interfacial tension and fluid velocity combine to increase capillary number. Increases in capillary number are associated with reduction of residual oil saturation.
Core experiments are related to the results of these studies. The methods discussed can partially account for additional oil recovery in an MEOR process.