bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure Derivative Enhances Use of Type Curves for the Analysis of Well Tests
Authors: Pirard Y. M. , Bocock A. 
Published: December 2007

ABSTRACT
Numerous type-curves of dimensionless pressure versus dimensionless time have been developed in the past. They all suffer from the fact that the log-log representation has poor resolution at late time, thus the uniqueness of the match is reduced.
The semi-log representation enhances the character of the pressure response but, because of the cartesian pressure scaling, the type curve technique cannot be applied. This drawback is alleviated by plotting the slope of the semi-log curve (i.e. the pressure differentiated with respect to the logarithm of time) on a log-log grid. The pressure type-curves differentiated in the same manner can thus be matched to the derivative data. The matching procedure is further improved by combining on the same plot both pressure and derivative data.
Field examples are presented showing how interpretation is enhanced by using the derivative. It is shown that the derivative sheds light on facets of pressure response that were imperceptible on pressure data alone.
The derivative can also be used to deconvolve pressures during the afterflow period of a build up, to compensate for the wellbore storage effect. Provided the wellbore storage coefficient is reasonably constant, the true reservoir response, which is masked at early times by wellbore storage, can be restituted allowing interpretation of early time data. This proves especially useful in the case of heterogeneous formations with permeabilities on the high side, as demonstrated by the examples.
Techniques for Simulating Complex Reservoirs
Authors: Hillestad J. G. 
Published: December 2007

Abstract
Advances in computing hardware and software have provided the reservoir engineer with a wide range of alternatives in analyzing and projecting reservoir behavior. The ability to economically run large simulation models offers a means to generate more accurate technical answers and to develop full-field models of larger, more complex reservoirs. However, there are still situations, due either to reservoir complexity or size, in which full-field models will not be practical. Therefore, detailed segment models will continue to be an important part of reservoir behavior analysis and development planning, and there is still a need for approximate approaches, such as the use of pseudo relative permeability and capillary pressure functions.
Delineation of River-Channel Reservoirs by Seismic Lithologic Modeling of 3-D Seismic Data in Southern Alberta
Authors: Gelfand V. A. , Taylor G. , Tessman J. , Larner K. L. 
Published: December 2007

SUMMARY
Although river-channel reservoirs are attractive because of their potential high porosity and permeability, their development is difficult because of rapid variations in the distribution of sands and shales. The Taber-Turin area of Alberta, Canada is a known oil province characterized by such reservoirs. To delineate potential reservoirs in detail, a 4 -km 3-d seismic survey was conducted, resulting in a square grid with traces 20-m apart. The Seismic Lithologic Modeling (SLIM™) process, an automated procedure that refines initial geologic models, was then applied to provide a thin-layer interpretation of the processed data. Although the initial model for the SLIM process was based on information from only one borehole (primarily for calibration purposes), the derived velocity model revealed, in detail, the thin Glauconitic reservoirs (0-30 m thick) that are the targets of the delineation effort. All six boreholes previously drilled in the area, four of them producers and two dry, are consistent with the SLIM interpretation. With the help of the SLIM results, three additional boreholes were proposed. To date, two of them have been completed, and both are oil producers.
Drill-Stem Testing From a Floater: The Practical Approach
Authors: Rolleg M. E. 
Published: December 2007

ABSTRACT
Many different aspects of DST procedures must be considered in floating drilling operations. Over the years, viable procedures have been developed as DST technology, equipment and quality of data have improved. This papr discusses actual field-developed operational procedures and proven equipment applications based on floater operations conducted in the South China Sea, Gulf of Mexico, North Sea and Mediterranean Sea from the deployment of semisubmersibles, shipshaped rigs and drilling barges.
Prediction of Miscibility for the Enriched-Gas Drive Process
Authors: Kuo S. S. 
Published: December 2007

ABSTRACT
Minimum miscibility pressure (MMP) is an important parameter for screening and selecting reservoirs for miscible gas injection projects. This paper presents a new correlation for the enriched-gas process that can be used to calculate the miscible slug compositions which consist of methane and mixtures of intermediate molecular weight hydrocarbons such as ethane to butane. The miscibility correlation was developed from MMP predictions of four reservoir fluids and several enriched-gas mixtures using the Peng-Robinson equation-of-state model. The correlation can be used to predict MMP for a fixed slug composition, or predict methane concentration for a given operating pressure. The correlation was tested with published data and showed an average prediction error of ± 2.5 mol% methane.
The miscibility conditions for two reservoirs and several enriched-gas mixtures were also determined in this study using slim tube apparatus. The miscibility in the slim tube tests was judged from the change of phases in the miscible transition zone rather than arbitrarily choosing oil recovery at the 90% level. A photosensor was used to aid the determination of miscibility. This experimental technique has proved to be very consistent. The results of these tests were compared with the new correlation and showed an average prediction error on MMP of less than ± 4%.
In general, either a higher pressure or a higher concentration of C2 to C4 hydrocarbons in the injection gas is required for achieving miscibility as (1) reservoir fluid C5+ molecular weight increases, (2) average molecular weight of C2 to C4 components in the injection gas decreases, or (3) reservoir temperature increases.
Photoelastic Modeling of a Complex Welded Structural Assembly
Authors: Fowler David W. , Panak John J. , Matlock Hudson 
Published: December 2007

Publication Rights Reserved
This paper is to be presented at the Society of Petroleum Engineers of AIME Symposium on Offshore Technology and Operations to held in New Orleans, La., May 23–34, 1966, and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustration, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Technology or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. publication elsewhere after publication in Journal of Petroleum Technology or Society of Petroleum Engineers Journal is granted on request, providing proper credit is given that publication and the original presentation of the paper
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting, and with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
A welded bracket supporting the leg of an offshore drilling unit was investigated by means of a photoelastic model after proving to be too complicated for analysis. The steel plates were modeled by plastic sheets and welded joints were simulated with epoxyresin. The model was subjected to different loading and restraint conditions. Stresses were computed from readings taken with a reflecting polariscope. The tests demonstrated that welded structural assemblies may be reasonably simulated by the epoxy-to-plastic combination.

Introduction
A complex welded bracket supporting the leg of a mobile drilling unit proved to be too complicated for theoretical analysis. An experimental model investigation seemed to be the most logical solution since the large size of the bracket made full-scale testing impractical.
A photoelastic model (Fig. 1) was constructed in which steel plates were modeled by birefringent plastic sheets and welded joints were simulated with epoxy resin; the more usual procedure is to bond the plastic sheets to the actual structure or model itself. Static load was applied to the model by means of dead weights on a pin that transmits forces to a leg of the structure in the prototype. The bracket model was tested with two different degrees of restraint corresponding to two different assumptions about the support offered by the hull of the barge. As in the prototype, reinforcing billets and struts were added to the model structure. Photoelastic readings were taken by means of a reflecting polariscope. With the model fringe values of the plastic sheets known, the stresses in the model were determined. Prototype stresses can be easily scaled from the model stresses.

PHOTOELASTICITY
David Brewster's discovery in 1816 that some materials become doubly refractive when subjected to stress marked the beginning of the science of photoelasticity.
The Pressure Transient Behavior for Naturally Fractured Reservoirs With Multiple Block Size
Authors: Cinco-Ley H. , Samaniego V. F. , Kucuk F. 
Published: December 2007

ABSTRACT
A new analytical model is presented to study the pressure-transient behavior of a naturally fractured reservoir composed of a fracture network and matrix blocks of multiple size. Matrix blocks are considered to be uniformly distributed--through a reservoir of infinite extent. A general model for fluid transfer between matrix and fractures is established; this model justifies the use of both the Warren and Root model and the transient matrix flow model for double porosity systems.
The multiple block size situation is handled through the use of a distribution function f(hma) that represents the fraction of matrix pore volume contained in blocks of size hma. It is demonstrated that classical parallel semilog straight lines can be present under these circumstances and the transitior zone may exhibit the characteristic half slope straight line when there is no flow restriction between matrix and fractures; --however, the transition between the end of the second and the third semilog straight line appears to be longer. It is found that the behavior of this type of systems is dominated by matrix of smaller size and the matrix blocks size computed from well testing by using the semilog straigt line intersection method corresponds to the weighted harmonic average; that is, in discrete form 1/h¯ma  =  Σi=1NB  f i/hmai where NB is the number of block sizes.
On the other hand, the λ value from well test analysis corresponds to the arithmetic weighted average, that is λ  =  Σi=1NB  f iλ i. These findings are important wher applying the transient pressure result to waterflooding project design.
Mixing in Underground Storage Reservoirs
Authors: Carrière J. F. , Fasanino G. , Tek M. R. 
Published: December 2007

ABSTRACT
Underground storage fields developed on aquifers or converted from producing reservoirs frequently encounter problems related to molecular transport and mixing phenomena. The need for understanding flow and displacement processes as affected by mixing and dispersion in the porous matrix surrounding storage wells is important, both in design and operation of storage units.
There are four specific occasions where mixing and dispersion takes on practical significance in storage: Total or partial conversion of working inventory from native to pipeline quality dry gas.Use of the storage unit for selective storage of gases having different compositions.Prospects of replacing part of the cushion gas by a lean or inert substitute.Use of chemical or radioactive tracers in investigating possible leak paths.
In order to provide a capability to predict the field performance as affected by mixing and dispersion, a new methodology has been developed which emphasizes numerical simulation implemented by appropriate computer programms. The programms permit calculation and graphical tracking of the front separating the gases involved in the miscible displacement process as affected by heterogeneities, operating conditions and the physical dispersion. Identification of physical parameters necessary for appropriate modeling is included.
The field data reported in the paper include one storage reservoir where an entire working inventory and about half of the cushion gas, have been displaced by cycling a gas of different characteristics. Similar conversions are currently being planned for two other storage reservoirs in the next few years.
In an area which will have profound implications in economics of underground storage, interesting data have been collected by substituting inert gas for part of the cushion gas in two storage reservoirs. One of these substitutions has recently been completed while the other is in progress.
Estimation of the Coefficient of Inertial Resistance in High-Rate Gas Wells
Authors: Noman R. , Shrimanker N. , Archer J. S. 
Published: December 2007

ABSTRACT
The pressure drop due to non-Darcy flow in a gas well producing at high rates can be determined from analysis of multi-rate pressure test data. In the absence of such data calculation of the non-Darcy term requires a knowledge of the coefficient of inertial resistance.
This paper presents correlations for estimating the coefficient of inertial resistance from reservoir porosity, permeability and gas saturation. These correlations were derived from analysis of multi-rate pressure tests conducted in over one hundred gas wells and are supported by experimental data using core plugs. They are found to be better than other published relationships in predicting observed performance.
Chemical Stability of Polyacrylamide Under Simulated Field Conditions
Authors: Yang S. H. , Treiber L. E. 
Published: December 2007

ABSTRACT
The chemical instability of Polyacrylamide polymer during both polymer and micellar-polymer flooding can seriously affect flood performance. Results of this study utilizing special laboratory techniques and long-term tests to simulate conditions typical of petroleum reservoirs show the effects of key variables on chemical stability. The rate and extent of degradation are governed most by oxygen content (although limited oxygen produces only limited degradation) and temperature. Metal ions, pH, and redox reactions can also have a major influence on degradation.
Prediction of Formation Response from Fracture Pressure Behavior
Authors: Conway M. W. , McGowen J. M. , Gunderson D. W. , King D. G. 
Published: December 2007

ABSTRACT
During examination of numerous treating pressure charts, it was discovered that most wells exhibited predictable pressure changes which could be classified into a limited number of generic formation treatment types. Once a limited number of calculations of bottom-hole treating pressure (BHTP) and instantaneous shut-in pressures (ISIP) are obtained early in the treatments, these formation type curves can be utilized to identify the anticipated pressure changes during the treatment.
Subject paper identifies five basic types of treating pressure behaviors with physical interpretations describing the proposed fracture geometry associated with each response. An optimum fracture treatment is proposed as an aid for fracture pressure interpretation both during the treatment and during post-job analysis.
Guidelines for post-treatment analysis are presented showing the use of treating pressure history as an aid to improving future fracture treatment design in a given formation.
Four-Parameter Modification of the Lawal-Lake-Silberberg Equation of State for Calculating Gas-Condensate Phase Equilibria
Authors: Lawal A. S. , Van der Laan E. T. , Thambynayagam R. K. M. 
Published: December 2007

ABSTRACT
The rapid development of digital computers during the past several years has made the calculation of hydrocarbon phase behavior feasible by methods based on rigorous thermodynamic principles. A number of these methods report comparisons of cubic equations of state (EOS) and laboratory PVT results for a wide variety of reservoir fluids and conditions. Most of them emphasize the C7+ fraction splitting as the key element in attaining an agreement between EOS and laboratory results. The work reported in this paper reflects our experience with predictive EOS without splitting C7+ fraction to match laboratory data. The use of the Four-Parameter modification of Lawal-Lake-Silberberg (LLS) EOS has made the splitting of C7+ fractions and the adjustment of EOS parameters unnecessary.
A modification of the LLS EOS has been formulated specifically for application to gas condensate reservoir fluids. The modification consists of establishing the heptanes-plus coefficients, αc7+, βc7+ in the attractive pressure term and new parameters for Ac7+ and Bc7+ which are related linearly to the characteristic properties of heptanes-plus fractions. These characteristic properties, molecular weight, API gravity, and Watson characterization factor are obtained from 4460 experimentally determined data points of condensate reservoir fluids which cover a range of temperatures from 40°F to 322°F and pressures up to 15,500 psia. The usefulness of the modified LLS EOS in improving phase equilibria predictions of complex systems without splitting C7+ fraction is illustrated by applying the EOS to several crude-oil and gas-condensate systems. The LLS EOS was also applied in predicting laboratory PVT data of published multicomponent systems which contain significant amounts of aromatic hydrocarbons. The prediction results of applying other equations of state (PR, SRK) without altering their parameters are also presented for comparison.
Automatic Facies Analysis in the Arab Formations, El Bunduq Field, Offshore Abu Dhabi/Qatar
Authors: De La Cruz M. A. , Takizawa H. 
Published: December 2007

ABSTRACT
A computer-based program has been used for zonation of wells into electrofacies according to log responses. The process determines a number of clusters from similar log values.
To ensure that the electrofacies obtained are geologically meaningful, log responses from key wells were calibrated with geological facies from cores. Input logs were selected accordingly.
The creation of a data bank helped to obtain consistency in the twenty-six wells processed in El Bunduq field offshore Abu Dhabi/Qatar.
The complex and variable lithology of the Arab formation provided good log contrasts for clear zonation into eleven electrofacies which were identified with facies described in cores. The occurrence of these electrofacies reflects their origin in different sedimentary and diagenetic environments.
The following stratigraphic relationships were observed: –The cyclical character of the upper Arab formations A, B, and C showing several carbonate-anhydrite cycles (electrofacies F7 to F16)–The thickness and frequency of the anhydrite beds increase upwards from the Arab C to the Arab A (electrofacies F7).
Correlation of electrofacies from well to well indicates that: The high complexity of diagenetic facies and their lateral changes affecting reservoir quality can be monitored.Reservoir quality in the Arab C increases towards the crestal zone due to the occurrence of less anhydrite (F7, F8) in the carbonate facies.In the Arab D, porous electrofacies F3 and F5 (porous and dolomitic mudstones) are well represented in the crestal part of the field but get very thin or pinch out towards the flanks.
Developments in the Simulation and Design of Multiphase Pipeline Systems
Authors: Norris H. L. , Fuchs P. , Malnes D. , Klemp S. 
Published: December 2007

ABSTRACT
Two-phase pipelines offer the potential for substantial cost savings in the offshore transport of hydrocarbons. Their design has been hampered by uncertainties in two-phase pressure drop relations, in flow regime determination, and in liquid slug length prediction. This uncertainty makes difficult the choice of pipe size and the design of downstream separation facilities. In order to reduce the uncertainty in two-phase flow pipeline design, Esso, Statoil, Mobil, Texaco, and Getty have sponsored the construction of the Norwegian Two-Phase Flow Laboratory now being operated by SINTEF. A large pipeline-riser expe imental facility has bee constructed to obtain laboratory quality data in a field scale apparatus. In addition, analytical modeling о two-phase flow is proceeding to provide a framework for interpretation of the experimental measurements. The experimental facility, results of experimental measuremen s, and analytica modeling techniques are described. The two-phase flow data and analysis resulting from this project promise to reduce substantially the uncertainty in the design of two-phase pipelines and downstream separation facilities.
Enhanced Oil Recovery by Surfactant-Enhanced Volumetric Sweep Efficiency
Authors: Arshad A. , Harwell J. H. 
Published: December 2007

ABSTRACT
A new enhanced oil recovery process is proposed for improving volumetric sweep efficiencies in reservoirs. The new process makes use of the chromatographic and phase separation behavior of surfactants to seal off high permeability, low residual oil saturation regions of reservoirs. Though making use of surfactants, the new process is not to be confused with classical (low tension) surfactant flooding, which is designed to enhance oil recovery by reducing oil/water interfacial tensions. In the new process, a sequence of surfactant species is injected into the reservoir. Those injected last are chosen to have higher chromatographic velocities than the former. The species are also chosen so that when they mix in situ, a phase separation occurs, resulting in formation of a pore blocking precipitate or of a high viscosity gel-like coacervate phase. Because the oil recovery mechanism is completely different from that in low tension surfactant flooding, the new process can operate at much lower surfactant concentrations and higher injectivities, greatly reducing the upfront costs of the new process, improving its economic feasibility. Sandpack studies are presented to demonstrate: 1. The process mechanism, 2. The ability of ppm concentrations of surfactant to plug porous media on in situ mixing, 3. The ability of the process to selectively plug high permeability regions, 4. The ability of the process to produce a tertiary oil recovery from a sandpack. Various potential advantages of the new process over other currently developing sweep efficiency enhancement processes are also briefly discussed.
New Technology and Tools for the Recovery of Representative Cores From Uncemented Sand Formations
Authors: Tibbitts G. A. , Radford S. R. 
Published: December 2007

ABSTRACT
Coring the uncemented Faja Petrolifera del Orinoco oil sands in Venezuela is a difficult operation. In order to obtain better formation characteristics from the Faja oil sands, a laboratory research program was conducted to develop techniques and equipment to core these sands. The laboratory tests showed that specific coring parameters and mud compositions must be maintained during the coring process, and that a fully open entry and full closure core barrel coupled with a polycrystalline diamond compact core bit are essential to successful core recovery. These techniques and equipment were then used to recover uncemented sand in the field.