bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Adsorption and In-Situ Rheological Behavior of Xanthan Solution Flowing Through Porous Media
Authors: Huang Yaduo , Sorbie K. S. 
Published: December 2007

ABSTRACT
The dynamic adsorption and in situ rheological behaviour of xanthan biopolymer flowing through porous media have been investigated. Results are related to the depleted layer effect, where polymer/pore wall interaction due to steric hindrance leads to a lower Newtonian apparent viscosity than bulk Newtonian viscosity. Previous work on the depleted layer phenomenon has been presented considering the effects of polymer concentration over the very dilute regime, pH and salinity on xanthan rheological and transport behaviour in porous media. Experimentally, the apparent viscosities of xanthan solution flowing in the ballotini glass bead packed columns were measured under various conditions and compared with the corresponding bulk viscosities. The experimental data were analysed using simple analytical models (two-fluid model and linear layer model) in- order to estimate the apparent depleted layer thickness. The results presented in this paper extend some of our earlier findings on the effect of both polymer concentration and salinity on the apparent depleted layer thickness. The main new results presented in this work concern the effect of xanthan dynamic adsorption on the in situ polymer rheology and depleted layer thickness. The depleted layer effect is measurable both before and after dynamic adsorption has reached equilibrium. However, the additional effect of the adsorbed layer close to the pore wall is small indicating that xanthan molecules are adsorbed very flat against the pore wall.
Numerical Investigations of Steam and Hot-Water Flooding in Fractured Porous Media
Authors: Jensen T. B. , Sharma M. P. , Harris H. G. , Whitman D. L. 
Published: December 2007

ABSTRACT
Effective and economic recovery of oil from fractured reservoirs by steamflooding rely on thorough understanding of the physical process mechanisms. The objective of this research is to study steamflooding mechanisms in fractured porous media using laboratory experiments and mathematical modeling. The experimental results have been published previously [1-3]. A mathematical model developed for simulating laboratory coreflood results is presented in this paper. The model is a two-dimensional, three phase, thermal simulator which includes the effects of gravity, capillarity and thermal swelling. Thermal effects on capillary pressure and relative permeabilities are included. Simulation and analysis of laboratory experiments are presented. Sensitivity studies demonstrate the effects of injection rate, pressure and temperature, fracture aperture, capillary pressure, and relative and absolute permeabilities on oil production.
Outlook for Calibration of Large Grid Block Models for Miscible Flooding Applications
Authors: Gorell S. B. 
Published: December 2007

Abstract
This paper discussesthe outlook for Large Grid Block (LGB) models as predictive tools. The interactions between viscous fingering and heterogeneity are considered for combinations of secondary miscible, immiscible, and continuous and Water-Alternate-Gas injection tertiary miscible displacements. The approach uses detailed simulations in very fine-scale heterogeneous grids to calibrate simpler analytic and coarse grid models. It concludes that although much progress can be made in calibrating continuous solvent injection LGB models, these same models prove to be less reliable for more complicated situations, such as Water-Alternate-Gas injection. In particular, for continuous solvent injection: (1) The mixing parameter model can be calibrated with a potentially measurable indicator of heterogeneity to match secondary miscible recovery and injectivity. (2) Integrations between heterogeneity and effective relative permeability can be calibrated with this same indicator of heterogeneity. (3) These calibrations for secondary miscible and purely immiscible displacements can be combined and reasonably applied to tertiary miscible displacements. However, severe complications arise when considering Water-Alternate-Gas injection, particularly in heterogeneous systems which are not at their residual saturation. These complications result because: (1) The mixing parameter must vary with WAG ratio and cycle size. (2) The effective relative permeabilities depend on the nature of the phase being injected. In these situations, it is not possible to simultaneously match breakthrough times, recoveries and injectivies using a single set of LGB parameters.
Profile Control in Virginia Hills EOR Injectors
Authors: Jones P. W. , Baker R. O. 
Published: December 2007

ABSTRACT
The ability to control solvent placement is critical to the success of any tertiary miscible flood in a stratified reservoir. In 1989, Shell Canada implemented a hydrocarbon flood in a heterogeneous Devonian reef at Virginia Hills. Injection profiles in this field are dominated by high permeability streaks. Since the miscible flood began, injection profiles have been improved using both mechanical methods and chemical blocking agents, resulting in increased oil and decreased solvent production.
Nine wells have been completed with mechanical profile control equipment. Multi-packer completions with different-sized- orifice valves allow control of injection volumes into each layer. Mechanical design details are presented and resulting field performance is discussed.
The philosophy and design of chemical profile control treatments are discussed. Prior to implementing chemical profile control, industry experience was reviewed and modified to improve the probability of success. The details of three chemical treatments are given in the paper.
Case History of South Belridge, California, In-Situ Combustion Oil Recovery
Authors: Ramey H. J. , Stamp V. W. , Pebdani F. N. , Mallinson J. E. 
Published: December 2007

ABSTRACT
Pilot in-situ combustion oil recovery operations began in the South Belridge Field in 1963, and commercial operations began on a 164-acre area in 1964. This operation ended in 1986 when an air compressor failed. South Belridge oil in place of a third of billion barrels of oil with an estimated 8 percent recovery inspired interest in thermal oil recovery in 1947. This study presents results of 22 years of commercial in-situ combustion at South Belridge.
Although continuous steam injection is the most important thermal oil recovery operation in South Belridge, in-situ combustion offers opportunity for extending thermal operations in other fields far beyond bounds appropriate for steam injection. Results at South Belridge for both commercial steam injection and in-situ combustion have been published. Steam injection is among the best in California, and in-situ combustion is considered average for California conditions.
At South Belridge, the surface energy requirement per barrel of oil produced by in-situ combustion was about one fifth that required for steam drive. The pounds of flue gas generated per barrel of oil recovery from in-situ combustion was about half that required for steam drive. Emulsions were produced by in-situ combustion, but posed no special problems. Well failures for in-situ combustion were similar to those for steam drive once old (pre-1964) completions were replaced.
The ratio of cum. inj. air to cum. prod. oil was 3.7 MCF/BBL, about a third of the design ratio. In-situ combustion offers an efficient extension of thermal enhanced oil recovery to deep, high-pressure, low-oil-reactivity formations.
The Effect of In-Situ Pore Pressure on MEOR Processes
Authors: Jenneman G. E. , Clark J. B. 
Published: December 2007

ABSTRACT
Most laboratory work in MEOR, both in screening and in development, is performed under in situ temperatures and in brines similar to those of the target reservoir. However, the effect of in situ pore pressures in such work is normally ignored. Much of our understanding of the effects of hydrostatic pressure on microorganisms comes from studies of microbial communities at the ocean floor. Since nearly 90% of the ocean floor has pressures ranging from 10 MPa to over 100 MPa, there is a paucity of data concerning effects on microorganisms at the lower pressures found in many oil reservoirs.
In our studies of the indigenous cells from injection brine at the North Burbank Unit, we have found that pressures ranging from 0.1 MPa to 8.8 MPa can have a significant effect on pH changes, substrate utilization, end product formation and permeability reduction. In general, hydrogen ion concentrations and carbohydrate utilization rates increased with increasing pressures. Methanol was found to be a significant end-product in the presence of hydrostatic pressure but found to be absent under atmospheric conditions. The fact that some of the observed effects could be demonstrated by simply reducing the gas headspace suggests that gas solubility could be an important factor. Gas formation in a core was estimated to account for as much as 50% of the permeability decrease observed in cores run under atmospheric pressure. Therefore the changes observed are of such magnitude as to alter the MEOR process in the reservoir from that indicated by laboratory studies not done under pressure.
Our results strongly suggest that all MEOR studies pertaining to a known reservoir should be evaluated under the in situ conditions of the reservoir, including pressure.
Iran's Petroleum Industry (Situations and Prospects)
Authors: Ebneyousef M. H. , Bogart A. J. 
Published: December 2007

ABSTRACT
During the past several years Iran's potentials have been forgotten or ignored by the outside world mainly due to misconceptions, fears, and political concerns attributed to the religious overtone. The intention of the authors is to present a broad and general introduction to the new realities of regional, as well as global geopolitics and the main political and economic aspects of Iran's huge and growing petroleum industry.
The fact of the matter is that in the rapidly changing world order the need for a true stability in the region and a global cooperation has been recognized by Iran.
The country, with a population of 60 million, is now preparing itself for the major political and economic role thrust upon the nation by the socio-economic changes in the integrating Europe; the outcome of the Iran-Iraq and the Persian Gulf wars, including the likely instability of the autocratic governments of Arab states of the region; the breakup of the former Soviet Union; and market changes in the Far East. Consequently, in recognition of the internal and external needs, Iran is expanding relations with the outside and expects to rebuild and develop its economy with the assistance of the industrialized nations for mutual benefits.
Understanding and recognition of these changes is the idea, for which the time has come.
A Review of Oil and Gas Reserve Acquisition Activity and Its Contribution to Company Performance
Authors: Johns C. E. , Gailey J. D. 
Published: December 2007

ABSTRACT
This paper analyses the contribution which reserve acquisition has made to the ability of a representative group of Oil Companies to replace their total reserve base over the 5 year period 1986-1990. It comments on the relative costs of replacing reserves through Acquisition compared to Exploration. The inadequacies of cost/bbl as the sole measure of Acquisition effectiveness are recognised and a value related measure is proposed which could be of general applicability to acquisition assessment. This approach is applied to 20 Acquisition examples which have taken place, mainly in the UKCS, over a similar time period, identifyinq the ability of the acquirer to realize value. The results indicate, as might be expected, that the individual acquisitions vary significantly in the value to the acquirer both at acquisition and subsequently. Several factors which influence the ability of the acquirer to realize value are investigated. It is argued, that the ‘premium’ ascribed to acquisitions in the UKCS is declining over time.
Integrated Reservoir Description
Authors: Holden Lars , Omre Henning , Tjelmeland Håkon 
Published: December 2007

Abstract
The main challenge in reservoir description is to integrate the different data sources and in particular be able to handle the uncertainty in the reservoir description. This paper presents a stochastic approach which integrates the different data sources. The method presented may be used for improving the predictions of the performance and for assessing the associated uncertainties. The latter is, however, a more complicated task.
The method consists of a combination of many different techniques, each of them used to model particular reservoir phenomena. The examples shown includes the use of Gaussian random fields, marked point processes and Markov random fields and the respond variables are hydrocarbon in place, oil production and recovery factor.
High-Resolution Schemes for Conservation Laws: Applications to Reservoir Engineering
Authors: Pinto A. C. C. , Corrêa A. C. F. , Cunha M. C. de Castro 
Published: December 2007

Abstract
Standard finite-difference reservoir simulation considers single-point upstream weighting to approximate the components of the convective flow term at the interfaces between blocks. This procedure stabilizes the numerical solution, but introduces high levels of numerical dispersion, making difficult the correct interpretation of the simulated results.
Exponential schemes are reasonable when diffusion dominates, but, as we show in this work, reduce to the single-point uspstream scheme when flow is too convective. A new and simple expression for the finite-difference form of linear conservation equations is derived for the exponential schemes.
Higher-order methods, like Leonard scheme, are able to reduce the numerical dispersion, but may produce non-physical solutions when the conservation equation assumes a hyperbolic form. We demonstrate, through the numerical solution of some classical non-linear equations, that this occurs because the entropy condition is violated. The numerical solutions also show that Total Variation Diminishing (TVD) methods, recently introduced in the reservoir simulation area, have the remarkable property of producing high resolution solutions which respect the entropy condition, and, consequently, are physically consistent.
The main mathematical principles for conservation laws are summarized and a screening procedure to be followed by new numerical methods is detailed. The performance of various numerical methods is analyzed for some standard reservoir engineering problems: 1D convection-diffusion equation, Buckley-Leverett equation and 2D single-phase tracer flow. Stability is analyzed. TVD schemes were also implemented on a two-phase black-oil model, considering IMPES, semi-implicit and fully-implicit formulations. We also included options of tracer injection in the water phase, considering full dispersion tensor and adsorption with the rock. Comparisons are made with refined grid single-point upstream solutions and with semi-analytical solutions. Grid orientation effect is also investigated.
A LOTUS® Template for Calculating Well Logs
Authors: Mitchell R. J. , Taylor S. J. 
Published: December 2007

ABSTRACT
Calculation of well logs is a time consuming process. This template uses input parameters which consist of well name, location, county, state, formation name, starting depth, repeat interval, resistivity of shale, and irreducible bulk volume water which provides heading information for print outs. Required information from basic well logs are porosity, conductivity (optional), formation resistivity, resistivity of the formation water for the zone being calculated, resistivity of the mud filtrate, the porosity cutoff for pay in the zone being calculated and the salt water saturation cut off for the pay zone. These parameters are used to calculate apparent water resistivity, salt water saturation, bulk volume water, ratio of apparent water resistivity to input water resistivity, irreducible salt water saturation, resistivity volume of shale and a derived porosity value. A hard copy print out of the results is available through the Lotus® (Lotus® is a registered trademark of Lotus Development Corporation) print function. Using this template allows maximum control of the input parameters and reduces hand calculation time.
Identifying Recompletion Candidates in Stratified Gas Reservoirs
Authors: Hower T. L. , Decker M. K. 
Published: December 2007

ABSTRACT
A performance analysis technique is presented which can be used to identify recompletion candidates in producing gas fields. Through geological description and a field case history, it is demonstrated that p/z versus cumulative production curves can be diagnostic tools in identifying inefficient completions or wellbore damage in a stratified reservoir system. It is also shown that these wells can be recompleted or redrilled to add significant incremental reserves which would have otherwise been abandoned.
Previous theoretical work presented in the literature demonstrated that layered gas reservoirs producing without crossflow display non-linear p/z versus cumulative production curves. This paper presents field data which support that observation and concludes that the absence of this behavior in a stratified reservoir environment may be indicative of a recompletion candidate due to wellbore damage in one or more of the layers. A field case history is presented involving wells producing from the Mesaverde Group in the San Juan Basin of New Mexico. Wells which were originally completed with nitroglycerin were selectively recompleted to yield significant incremental reserves. These wells were identified by their linear p/z behavior in an area where theory and historical performance indicate a non-linear p/z curve should be present. The results of the recompletion program are presented.
Compressed Natural Gas for Vehicles and How We Can Develop and Meet the Market
Authors: Pinkerton W. E. 
Published: December 2007

ABSTRACT
State and federal legislation have mandated the use of clean burning fuels. "Clean fuels" include: compressed natural gas (CN6), ethanol, methanol, liquefied petroleum gas (LPG), electricity, and reformulated gasoline.
The Clean Air Amendments 1990 have created support for the rapid utilization of the compressed natural gas (CNG). Responsively, diverse occupations related to this industry are emerging.1 A coordinated infrastructure is vital to the successful promotion of clean fuels and synchronized endorsement of the law.
Reservoir Characterization of the Bakken Shale from Modeling of Horizontal Well Production Interference Data
Authors: Breit V. S. , Stright D. H. , Dozzo J. A. 
Published: December 2007

ABSTRACT
This paper describes the use of reservoir simulation to refine reservoir descriptions of the Bakken Shale for predictions of single well and multiple well performance. The descriptions were achieved by matching drawdown, buildup, and interference data from horizontal wells in the Buckhorn Field, McKenzie County, North Dakota, Figure 1.
Reservoir descriptions - matrix and fracture storativities, ϕCtH, and matrix and fracture permeability-thickness products, KmH and KfH -- were developed for both single well and multi-well interference data. More than one description could be found to match single well data; however, only one description was found which matched all the data. The best match of long term production interference data was obtained with a dual porosity description that included anisotropic, stress-sensitive permeability.
In the dual porosity model, both microgeneration fractures and enhanced or extension fractures were modeled with a lumped description. The permeability anisotropy for this lumped fracture system was approximately 4 to 1 with the maximum permeability direction in the northern Buckhorn area being east-to-west.
Bakken Shale porosity was determined to be 2 to 3 % with one-tenth of that volume or 0.2% being in microfractures. The ratio of fracture to matrix permeability was 100 to 1 with an effective permeability for the fracture system of 0.6 md at maximum net confining stress. It is believed that silt-stones and dolomites adjacent to the Bakken Shales make a significant contribution to the oil production through the extension fracture system.
An Analysis of Hydraulically Fractured Horizontal Wells
Authors: Brown J. E. , Economides M. J. 
Published: December 2007

ABSTRACT
Horizontal wells with lengths up to 8,000 ft are capturing an ever-increasing share of all wells drilled. However, the performance of many of these wells is significantly less than what is predicted by published well performance models. The factors causing this variance must be understood if horizontal wells are to produce at their potential.
Methods are presented in this paper that demonstrate which reservoirs may benefit from horizontal wells instead of fractured vertical wells. Additionally, an extensive analysis of expected performance shows that many horizontal wells may also benefit from fracture stimulation, and that the vast majority of reservoirs that have traditionally been candidates for vertical well fracturing are obvious candidates for horizontal well fracturing.
There is a need to determine the in-situ stress directions before a horizontal section is drilled, even if hydraulic fracturing is considered unattractive. These contrasting stresses can greatly affect the producing potential of a horizontal well. Analytical approximations are offered which can account for the permeability anisotropγ expected in these cases. Performance comparisons demonstrate that a horizontal well must be drilled in accordance with these stress measurements to maximize production rates.
Case histories are used to demonstrate both successes and failures of hydraulically fractured horizontal wells. Various completion practices are reviewed and their corresponding results are explained.
Drawdown and Buildup Pressure Derivative Analyses for Horizontal Wells
Authors: Issaka M. B. , Ambastha A. K. 
Published: December 2007

ABSTRACT
Horizontal wells are becoming popular for primary and enhanced oil recovery operations because of unique advantages of horizontal wells in comparison to those for vertical wells. However, horizontal well testing is considerably more complex than vertical well testing.
This study uses numerical integration to evaluate an analytical solution for the transient pressure response of a horizontal well located in a closed, box-shaped, anisotropic reservoir. Results from this study show that numerical integration can be used to evaluate the solution with a comparative degree of accuracy, while avoiding the convergence problems associated with the analytical integration. Both drawdown and buildup responses have been studied.
New time criteria, based on the semi-log pressure derivative response, are proposed for well test analysis and design purposes. These time criteria generally suggest shorter flow period durations than those corresponding to the time criteria based on the pressure response. The effects of well radius, well location and reservoir size on the drawdown pressure derivative response are discussed.
Producing time effects on the buildup pressure derivative responses are also investigated. Results show that for a horizontal well in a closed reservoir, the late linear flow period will not occur on the buildup response for any case, even when the late linear flow period is present on the drawdown response. Design equations are presented for the time at which buildup response deviates away from the corresponding drawdown response to establish the applicability and limitations of using drawdown type curves to analyze buildup data obtained from a horizontal well.