bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of a Gas Kick Taken in a Deep Well Drilled With Oil-Based Mud
Authors: Tarvin J. A. , Walton I. , Wand P. , White D. B. 
Published: December 2007

ABSTRACT
A gas kick taken in a deep well drilled with oil-base mud is simulated with a new model. In comparison to one taken in water-base mud, this kick shows relatively small increases in annulus pressure and pit level as the gas is circulated to the surface. Solubility of the gas in the drilling mud is the key to understanding these measurements. Even though the formation permeability is the only adjustable parameter in the model, the calculated surface pressure is very close to the measured pressure throughout the slow-circulation phase.
Controlling Kicks in Ultradeep Wells and Comparison With Shallow Wells
Authors: Schöffmann F. , Economides M. J. 
Published: December 2007

ABSTRACT
Kick control for ultradeep boreholes has certain important distinguishing features from the kick control for more "normal" depth wells. The annular pressure profile vs. time is different in the two cases because the initial shut-in pressure in the ultradeep holes is large and sometimes it is the largest during constant bottomhole pressure (CBHP) kick control, resulting in small gas expansion effects. In shallow holes, the lower initial shut-in pressure and low pressure level (compared to ultradeep borehole annular pressures) throughout the kick control operation results in significant gas expansion. Therefore the annular pressure during the kick control may be substantially higher than the shut-in pressure. Thus, the critical period between the two cases happens at a decidedly different time. Kick simulation for ultradeep holes is presented in this paper for different CBHP methods using waterbase muds in any borehole geometry. The worst case, that of a sudden influx of a gas slug is used. The results are profiles of surface annular pressures, identifying the largest pressure value at each depth during the kick circulation with the CBHP methods. This allows the quantification of the load on a borehole during controlled CBHP kick-killing-operations at any depth.
An Analysis of Relative Costs in Drilling Deep Wells
Authors: Andersen E. E. , Cooper G. A. , Maurer W. C. , Westcott P. A. 
Published: December 2007

ABSTRACT
INTRODUCTION
The search for new sources of oil, and particularly gas, is leading the industry to drill ever deeper wells. A depth of 15,000 ft was first passed in 1938, 20, 000 ft was reached in 1939, followed by 25, 000 ft in 1958, and 30, 000 ft in 1972. The current US record depth is 31,441 ft. As the total depth increases, not only does the rock to be drilled become stronger, but increasing pressure and temperature induce plasticity and "chip hold-down" effects that make it more difficult to remove cuttings from the workfront. In addition to the reduction in rate of the drilling process itself, other activities become more complex and time-consuming, for example, tripping, running and cementing casing, and logging and coring activities.
We have analyzed the different tasks involved in drilling deep wells, in order to identify those activities that contribute most to the overall cost. These are therefore expected to be the activities where future efforts in research and development should provide the greatest reductions in total cost.
OVERALL EFFECTS OF INCREARTNR DRPTH
We have obtained information from a large drilling database that contains data on over 3000 wells, drilled in all parts of the world, both on land and offshore, during the period 1977-1988. The majority of these wells were for exploration rather than production. Some of the major findings include the following:
U.S. Petroleum Engineering Manpower Supply & Demand: A Reversal of Trends
Authors: Ghalambor A. , Miller M. A. 
Published: December 2007

ABSTRACT
INTRODUCTION
The purpose of this paper is to report the results of the supply and demand surveys conducted annually by the SPE Manpower Committee1
As in previous years, the 1991 Demand Survey was sent to selected employers of petroleum engineering graduates, including major companies, independents, and service companies. A total of 33 companies responded to the survey. Twenty-eight were complete and usable.
Results of the survey indicated that total engineering employment in the upstream petroleum industry is expected to be essentially flat for the next couple of years, although there would appear to be a decline in the number of engineers employed by large producing companies, with corresponding increases by small producing companies and service companies. The supply/demand situation for new petroleum engineering graduates is expected to remain relatively steady.
Abnormal Permeability Behavior of a North Sea Sandstone Reservoir
Authors: Mikkelsen M. , Scheie Å. , Rong O. , de Boer E. T. 
Published: December 2007

ABSTRACT
Special core analyses on sandstone samples from a North Sea oil reservoir showed unusually large variations in absolute and effective permeability. Abnormally high endpoint relative permeability to oil was observed during primary drainage oilfloods. Absolute air permeability was in many instances several times higher than the absolute water permeability. In order to improve the understanding of the causes for this particular behaviour, a comprehensive laboratory core study was carried out.
Comparative studies on several suites of parallel samples showed that air permeability and primary drainage endpoint oil permeability were strongly dependent on experimental procedures. Miscible cleaning and critical point drying are preferred to conventional methods. Establishment of initial water saturation by oil flooding gave less change in permeability than centrifuge and porous plate methods. Water permeability was less sensitive to experimental procedures, but significant changes were still observed. A reversibility in permeability was noted with many samples; decreases were often observed when going from air or oil saturated plugs to water saturated plugs, whilst increases occured when going the opposite way.
The rock material was characterized with respect to mineralogy, morphology and pore size distribution. The study showed that the permeability effects seem to be dependent on the content of filamentous illite. Analyses of fluid effluents showed significant particle migration only in cases of two-phase flow.
The study demonstrated that control over experimental effects is important and demanding, but still achievable, for this type of sensitive rock. It contributed to an improved data basis for further reservoir evaluation and better understanding and procedures for future core analysis on this rock type.
European Innovation and Technology Development
Authors: Johnson R. W. 
Published: December 2007

ABSTRACT
The promotion of technological innovation by European national governments and the EC in pursuit of both increased recovery and the anchoring of technology in supply, manufacturing and service sector companies has been a feature of the strategic involvement by European states in exploration and production research and development. This paper summarises past trends in this activity and reviews the targets for future industry innovation which will enable European (primarily the North Sea) production to be sustained for a further generation.
A Theoretical Analysis of Vertical Flow Equilibrium
Authors: Yortsos Y. C. 
Published: December 2007

ABSTRACT
The assumption of Vertical Flow Equilibrium (VFE) and of parallel flow conditions, in general, is often applied to the modeling of flow and displacement in natural porous media. However, the methodology for the development of the various models is rather intuitive, and no rigorous method is currently available. In this paper, we develop an asymptotic theory using as parameter the variable RL=LHkVkH It is rigorously shown that present models represent the leading order term of an asymptotic expansion with respect to 1/RL2 Although this was numerically suspected, it is the first time that it is theoretically proved. Based on the general formulation, a series of models are subsequently obtained. In the absence of strong gravity effects, they generalize previous works by Zapata and Lake (1981), Yokoyama and Lake (1981) and Lake and Hirasaki (1981), on immiscible and miscible displacements. In the limit of gravity-segregated flow, we prove conditions for the fluids to be segregated and derive the Dupuit and Dietz (1953) approximations. Finally, we also discuss effects of capillarity and transverse dispersion.
Experimental Testing of Mobility Predictions in Averaged Models of Viscous Fingering
Authors: Sorbie K. S. , Tsibuklis N. B. , Dwebi A. 
Published: December 2007

Abstract
Averaged empirical models of viscous fingering are frequently used in order to incorporate the effects of miscible viscous instability into coarse grid simulations of processes involving adverse mobility ratio displacements. However, in order to evaluate these models, it is not sufficient to compare the predictions which they make with effluent profiles in 1D displacement experiments since this only tests the transport properties of the model. It is also necessary to compare the predictions of effective mobility of these models with experiment in order to evaluate their use for application in the modelling of multidimensional displacements. The effective mobility can only be assessed directly when the pressure drops are measured along the fingering zone in miscible unstable displacements and such experiments have not previously been reported. In this paper, miscible viscous fingering results have been presented for "2D linear" displacement experiments at mobility ratios of approximately M = 4, 11 and 30. Both effluent profiles (recoveries) and pressure drops along the fingers have been measured and the reproducibility of these in each of the experimental cycles in repacked beds is very good. The effluent and pressure behaviour has been modelled using direct fine grid numerical simulation and a number of averaged models of viscous fingering have been evaluated using the experimental pressure data including the Koval, Todd and Longstaff, Fayers and the Odeh and Cohen models. It has been found that direct numerical simulation reproduces both the experimental effluent concentration profiles and the observed pressure drop behaviour very well. However, of the averaged model approaches, the Todd and Longstaff and an equivalent mixing model give the most satisfactory agreement with the observed effective in situ mobilities (pressure drops) in the fingering zone. Both the original Koval model and the modification proposed by Odeh and Cohen do not give good agreement with experimental pressure drop measurements. The approach of Fayers also has some shortcomings in that it predicts a viscosity in the finger zone that is too low (i.e. effective mobility is too high) due to the presence of an unphysical shock front behaviour which this model exhibits.
Steam-Foam Diversion Process Developed To Overcome Steam Override in Athabasca
Authors: Sander P. R. , Clark G. J. , Lau E. C. 
Published: December 2007

Abstract
The Grégoire Lake In-Situ Steam Pilot (GLISP) was the first steam foam flood performed in Athabasca. The recovery process developed at GLISP used inherent reservoir characteristics to advantage. Inter-well communication was established in an upper zone of low oil saturation. Steam diversion using in-situ foam was then used to successfully mitigate steam override to that zone. Foam injection improved oil production by as much as 100%. Additional testing was performed to optimize surfactant and steam injection rates. This paper presents results of the steam foam testing, and is a case history follow-up of SPE 19690. GLISP production, injection and reservoir temperature profiles are used to outline the results of the steam foam diversion process.
Observation of Foam/Oil Interactions in a New, High-Resolution Micromodel
Authors: Hornbrook J. W. , Castanier L. M. , Pettit P. A. 
Published: December 2007

Abstract
A new micromodel construction procedure has been developed as a tool to better understand and model pore level events in porous media. The construction procedure allows for the almost exact two-dimensional replication of any porous medium of interest. For the case presented here, a berea sandstone was chosen.
Starting with a thin section of the porous medium of interest, a two-dimensional replica of the flow path is etched into a silicon wafer to a prescribed depth. Bonding the etched pattern to a fiat glass plate isolates the flow path and allows the pore level flow events to be studied.
The high resolution micromodels constructed with the new procedure were used to study the effects of oil on the displacement characteristics of foam in a porous medium of intermediate wettability. A crude oil was injected into the micromodel, partially filling it. The oil was then produced under two different displacement schemes. First, a slug of surfactant was used. Second, foam generated in situ, far from the oil bank, was used to displace the oil.
Qualitative observations indicate significant differences at the interface between the oil and the displacing phase. When slug surfactant injection is used, the oil appears to wet the surface. The oil displacement process is efficient due to a large fractional production of oil from the large pores before the surfactant breaks through. When in-situ foam is the displacing phase, the foam is observed to break near the oil interface. The liquid phase in the foam becomes the wetting phase. It is observed to reside in the small pores and to coat most of the grain surfaces. Displacement of oil under this injection scheme is inefficient due to transfer of the surfactant along grain edges and subsequent early breakthrough of the surfactant.
Mechanisms of Miscible Oil Recovery: Effects of Pressure on Miscible and Near-Miscible Displacements of Oil by Carbon Dioxide
Authors: Shyeh-Yung J-G. J. 
Published: December 2007

Abstract
This paper presents results obtained in a laboratory study investigating incentives for near-miscible CO2 processes. Reservoir-condition corefloods were completed in both idealized and West Texas-type fluid/ rock systems at pressures above and below the minimum miscibility pressure (MMP). Coreflood oil recoveries and CO2 mobilities are presented to examine effects of pressure, initial saturation, and volume of CO2 injection.
Results show that decreases in tertiary oil recovery at pressures below the MMP are not as great as suggested by slim tube tests. The presence of water in the core apparently reduces the pressure sensitivity. In addition, it was found that CO2 mobility is reduced by the presence of a miscible flood residual oil saturation (Sorm), which increases as the pressure decreases. Both observations suggest that lower pressure (near-miscible) CO2 EOR processes have potential to economically recover oil.
Two oil recovery mechanisms, low interfacial tension (IFT) displacement and extraction of oil components, were found to be important. This is deduced from analyses of produced oil compositions. Lower IFT (higher pressure) and lower initial water saturation enhance displacement and reduce pore level bypassing. Extraction dominates after solvent breakthrough; extraction increases with pressure and decreases with water saturation.
The work suggests that, whenever possible, slim tube tests be replaced with reservoir-condition corefloods which provide more realistic data not only on pressure sensitivity, but also on miscible flood residual oil saturation and solvent mobility.
Pseudo-Steady-State Flow and the Transient Pressure Behavior of Fractured Wells: A New Analytical Technique for Complex Wellbore Configurations
Authors: Collins R. E. 
Published: December 2007

ABSTRACT
An almost exact closed form analytical solution for the transient pressure behavior of a fractured well in an infinite domain is obtained by a new approximation technique of broad applicability. This solution is shown to yield a simple analytical expression for type curves which can be used to determine fracture length from a pressure build-up curve. It can also be used in a pressure interference test to determine fracture orientation. Most importantly, this paper is a tutorial for applying this solution technique to other well completion configurations.
Salinity Dependence of the Shaly Sand Formation Resistivity Factor, F*
Authors: Yuan H. H. 
Published: December 2007

ABSTRACT
The Yuan-Diederix equation relates the conductivity of a brine-saturated rock to the brine conductivity and membrane and Nernst potentials for the sample for a given salinity contrast. The equation has only one parameter, namely, the shaly sand formation resistivity factor, F*. Because the equation is essentially local in salinity, data from Waxman-Smits Group 2 samples for which conductivity and membrane potential data have been simultaneously measured allow the determination of F* as a function of salinity.
For situations where the clay conductivity is smaller than the brine conductivity, the Waxman-Smits assumption of constant F* is valid. However, where the clay conductivity exceeds the brine conductivity, F* may no longer be constant, implying that the Waxman-Smits assumption of constant F* is not always valid. An implication of salinity-dependent F* is that membrane potential measurements may be necessary for cases where the clay conductivity exceeds the brine conductivity. This can be critical for shaly sand evaluation.
New simultaneous conductivity and membrane potential data are reported for a set of very shaly sandstones which confirm the salinity dependence of F* when the clay conductivity exceeds the brine conductivity. The effect is greatest for montmori1lonite-bearing samples. Procedures for applying membrane potential measurements are described.
Outcrop Characterization of Flow Unit and Seal Properties and Geometries, Ferron Sandstone, Utah
Authors: Tyler N. , Barton M. D. , Finley R. J. 
Published: December 2007

Abstract
Outcrop studies provide high-resolution information about facies architectural controls on the spatial distribution of petrophysical attributes in reservoir analogs. One of the sandstones in the Ferron delta system in central Utah has been selected for detailed analysis as an analog of Gulf Coast deltaic reservoirs. Unit 5 of the Ferron, a wave-modified deltaic sandstone, consists of a meandering distributary system that fed stratified delta-front deposits. Lateral migration, coupled with rising base level, resulted in horizontally and vertically heterogeneous distributary sandstones, in contrast to the delta front where vertical heterogeneity is dominant and lateral complexity minimal.
Permeability distribution and structure are strongly related to facies composition, stratal type, and grain size. Thus, distributary-channel sandstones have the highest mean permeability, delta-front sandstones the lowest. Within the distributary system the trough-crossbedded stratal type has the highest mean permeability. Variogram analysis indicates correlation at several scales—largest correlation lengths are 182 m in the distributary-channel sandstones. At the stratal level horizontal correlation lengths are less than 6 m and relate to erosional discontinuities and bed size. Quantification of permeability characteristics suggests a hierarchy of bounding-surface types that have attendant geometric and permeability characteristics. Such characteristics can be critical input to reservoir simulation studies of analogous reservoirs in the Gulf Coast Basin, many of which are major natural gas producers.
Correlation of Capillary Pressure Relationships and Calculations of Permeability
Authors: Ma Shouxiang , Jiang Ming-Xuan , Morrow N. R. 
Published: December 2007

ABSTRACT
Correlation of capillary pressure data and the development of the widely used J(S) correlating function are reviewed. The pore structures of core samples, which give the same (in practice closely similar) J(S) curves, are described as operationally similar. Similarity of J(S) curves can be recognized by parallelism of semi-log plots of capillary pressure vs. saturation. Curves so identified were grouped to obtain a pore structure factor based on J(S) curve shapes rather than determining Purcell lithology factors for individual formations. The modified Purcell method gave improved correlation between measured and predicted permeabilities.
A general solution of the Thomeer model in terms of the tangent angle for the Pc(S) curve is presented which facilitates tests of correlations between permeability and selected features of capillary pressure curves. Single point correlation methods based upon the tangent α as introduced by Swan son for α=45°, are shown to hold for a wide range of saturation. Curve methods which consider all of the curve such as suggested by Purcell or any selected parts can be tested at will. The method is designed for semi-empirical investigation of a very large database of core analysis results which include porosity, permeability, and capillary pressure by mercury injection.
Centrifuge Capillary Pressure: Method of the Center of Forces
Authors: Jaimes O. 
Published: December 2007

ABSTRACT
Shown that the commonly used methods of reduction of centrifuge capillary pressure data, based on the Hassler and Brunner theory, lead to double valued capillary pressure functions. To avoid this problem, an alternate equation with two methods of solution has been developed. This equation uses the concept of the center of forces to convert centrifuge data into capillary pressure curves. The proposed methods do not make assumptions about the form of the solution, nor do they use numerical differentiation of experimental data, and, lastly, they do not result in double valued capillary pressure curves. Several examples, including laboratory and analytical data with the computed capillary pressure curves, are presented along with a comparison of the results obtained using the new and several previously developed methods.
Borehole Caliper while Drilling from a 2-MHz Propagation Tool and Borehole Effects Correction
Authors: Rosthal R. A. , Best D. L. , Clark B. 
Published: December 2007

Abstract
The Compensated Dual Resistivity (CDR*) tool computes two apparent resistivities, Rad and Rp8, from the attenuation and phase shift of a 2-MHz electromagnetic wave measured between two receivers. While these measurements are insensitive to the borehole in most situations, the relative phase between a receiver and a transmitter is quite sensitive to the borehole diameter and the mud conductivity. Since the mud conductivity is known, this sensitivity can be used to estimate the borehole diameter during drilling, tripping or washing down. This phase caliper can be obtained in real time using data transmitted to the surface, or it can be calculated after bit runs using data stored in the tool. The borehole diameter can then be used to apply borehole corrections to Rad and Rp8. The borehole correction algorithm can also use any other caliper or bit size as input. Graphs showing the borehole effects for a range of borehole sizes, mud resistivities and formation resistivities are presented. Log examples of the phase caliper and borehole-corrected resistivities are presented.
A Modified Scaling Law and Parachor Method Approach for Improved Prediction of Interfacial Tension of Gas-Condensate Systems
Authors: Danesh A. S. , Dandekar A. Y. , Todd A. C. , Sarkar R. 
Published: December 2007

ABSTRACT
The interfacial tension (I.F.T.) of petroleum reservoir fluids are commonly predicted by either the parachor method or the scaling law. Both methods have been evaluated against literature data of binary systems. The predictive capability of the methods have been improved by a simple modification of the original correlations. The superiority of modified methods have been demonstrated by comparing predicted results with experimental I.F.T. values for two gas condensate fluids at wide ranges of pressure and temperature.