bluuebunny/crossref_metadata_2025 huggingface dataset:
Fiscal Aspects of International Petroleum Agreements
Authors: Higgins J. G.
Published: December 2007

This paper examines the nature of exploration agreements that have been adopted around the world and demonstrates their effect on Government revenue receipts and Company project economics. It is based on a survey of current agreements covering some sixty countries.

Oil and gas exploration only takes place when agreement has been reached on the terms that govern the division of risk and reward between an oil Company and its host Government. This agreement frequently involves lengthy negotiations. The aim of this paper is to improve the understanding of the parties as to the effect of the variables involved. Greater understanding should improve the efficiency with which Companies and Governments reach such agreements.

The evolution of different forms of agreement and their fiscal mechanisms are compared with a view to recommending future improvements. The impact of each type of provisions, such as bonuses, royalties, and tax rates are quantified with respect to their impact on project economics. Graphical comparisons are used to demonstrate the impact of marginal changes to rates and provide a framework for developing changes.

It is the objective of this paper to provide an insight into the increasingly complex terms adopted for modern exploration licences and a practical approach for Companies and Governments to assess the relative merits of alternative fiscal regimes.
Reservoir Characterization With Crosswell Tomography: A Case Study in the Midway Sunset Field, California
Authors: Lo Tien-when , Inderwiesen P. L.
Published: December 2007

Laboratory measurements on tar-sand cores saturated with heavy oil show that seismic wave velocity decreases as the temperature increases. We use this physical effect to monitor the progress of a steam flood operation in the Midway Sunset Field in California. Results of seismic wave velocity tomograms acquired both before and after steam flooding show quite dramatically how temperature affects the seismic wave velocity. The heated heavy oil in the reservoir is delineated, and the information can be used by the production engineer for evaluating the progress of the EOR method.
The Lower Miocene Liuhua Carbonate Reservoir, Pearl River Mouth Basin, Offshore People's Republic of China
Authors: Turner N.L. , Hu Ping Zhong
Published: December 2007

Since the drilling in January 1987 of the Liuhua 11-1-1A discovery well, six additional wells, four on the primary structure and one each on two satellite structures, have drilled and tested this lower Miocene reservoir carbonate.

Deposition of the carbonates took place in isolated platform environment. Major facies are (1) a platform-rim reef, (2) a backreef platform-rim reef, (2) a backreef lagoon of fine grained carbonates, (3) a large interior platform algal bank, (4) platform coarse grained carbonates, and (5) platform to lagoonal fine-grained carbonates. A paleo-water table surface represents paleo-water table surface represents a time of regional exposure. The reservoir is subdivided into five diagenetic carbonate units. The uppermost unit is a thin, tightly cemented carbonate formed at the time of drowning of the platform. Two thick highly leached carbonate units with porosities and permeabilities as high as 30 percent and several darcies comprise most of the reservoir. They are separated by a tighter interval which formed by cementation below the water table of the exposure surface. The less porous unit at the base of the porous unit at the base of the reservoir formed as a result of interaction between oil and water caused calcite cementation. Leaching continued in the carbonate below the reservoir and biodegradation occurred after oil had filled the structure.

Introduction

Amoco in partnership with Nanhai East Oil Corporation discovered Liuhua Field in January 1987. The field is located offshore China about 220 kilometers (135 miles) southeast of Hong Kong in the Pearl River Mouth Basin of the South China Sea (Figure 1). This field was the first discovery of oil from a large carbonate complex in the basin and is located in Contract Area 29/04 and in water depths over 305 meters (1000 feet).

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Heather Field Re-Evaluation
Authors: Miller James A.
Published: December 2007

An integrated project was initiated to re-evaluate the Heather Field, in the UK North Sea. The project involved the facies description of core material, a study of the diagenetic history of important rock units, a structural reinterpretation of the field area, and an investigation of the petroleum generation and fluids migration. The sedimentary section grades upward from shallow shelf turbidites and fan deltas to major fluvial-deltaic systems, with delta-front/shoreface sediments, and finally delta plain and tidal flat facies. The diagenetic history is very complex, and includes K-feldspar overgrowths, and kaolinite, calcite, quartz and illite cements. A geochemical source rock study indicates that petroleum generation began in late Cretaceous and that there were two petroleum generation areas.
Horizontal Well Simulation by Numerical Model in a Carbonatic Field in the Mediterranean Sea
Authors: Mongini A. , Salvini G. , Puntri P. L. N.
Published: December 2007

This paper presents the methodology and the results of the analysis of an horizontal oil well drilled in the BOURI field (Libyan offshore).

It was decided to drill horizontal wells to reduce gas production that was higher than expected for both gas coning and gas fingering. The well B4-13H, the third horizontal well in the field, was drilled in August 1990.

The well is cased hole completed with a 7" cemented liner with two horizontal segments in two different layers. Due to this particular completion it is not possible to utilize the standard well test analysis package for quantitative analysis. It was therefore decided to perform a numerical simulation of the well with the following targets:

– Reservoir characterization of the zone – Understanding of the production behaviour – Optimization of the well rate and gas cresting prediction

The starting point of the analysis was the production test performed after two consecutive acid jobs (acid stimulation is part of the completion procedures).

The tool used to perform the numerical simulation is a sector model derived from the full field model with a grid refinement for a good simulation of the horizontal sections. Two slanted wells are also included in the sector model.

Moreover, an application of the numerical model is given.
Review of the 30 Years’ Experience of the CO2 Imported Oil Recovery Projects in Hungary
Authors: Doleschall S. , Szittár A. , Udvardi G.
Published: December 2007

In Hungary, the laboratory and pilot-tests on the application of CO2 containing gases for production purposes was started in the 1960's. In the early stage of experiments CO2 produced from flue gases was used and later, the production experiments were based on the natural gas of high CO2 content (81% v/v) explored under the Budafa oil producing field. The formation pressure at the Budafa deep-reservoir is so high that no compression is needed.

On the basis of promising experimental results, field-scale CO2 IOR operations have been started in Budafa-Field and in Lovászi--Field which are sandstone reservoir rocks, and in both, partially soluble methods have been applied. In these fields WAG (water- and -gas alternative injection) methods have been carried out.

At the present time, only the water injection is going on. In 1988, in one part of Nagylengyel-Field, a large scale artificial CO2 -gas cap cooperation was started. The Nagylengyel-Field is a carstic--cavern type reservoir with active bottom--water pressure, where during primary production gas recovery did not occure.

The production results are better than the expected.

This paper summarizes the main data of fields, the operational characteristics, and operational experience has been gained regarding the production, dehydration and transportation of CO2, and the surface facilities.

It is intended to expand the CO2 IOR method also for other parts of Nagylengyel-Field, and now the application of sweetened CO2 gas is under preparation, and an other CO2 project (for Szank-Field) is also planned.
Micellar Flooding in an Alkaline Environment Under Lao Jun Miao Conditions
Authors: Bazin B. , Yang Cheng Zhi , Wang De Chen , Su Xue Yi
Published: December 2007

This research was designed to develop an efficient micellar/polymer process for tertiary oil recovery at Lao Jun Miao (Yumen field, China), a reservoir with a high clay content, mainly smectites.

Preliminary laboratory tests indicated poor final oil recovery due to high retention of the sulfonate attributed to adsorption and precipitation by in-situ generated divalent cations as a result of ion exchange.

Alkaline additives were chosen for improving the process efficiency. This paper describes a number of preflush compositions and their effect on surfactant retention. With this strategy in view, a phase behavior study was carried out to formulate an efficient micellar slug for the tertiary recovery of Lao Jun Miao crude.

Additional insights into the implementation of the process are given. In particular, the design of the preflush composition was improved to prevent adverse effects such as clay swelling. The results demonstrate the technical feasability of micellar/alkaline/polymer flooding at Lao Jun Miao.
Fully Integrated Reservoir Study and Numerical Forecast Simulations of Two-Polymer Pilots in Daqing Field
Authors: Corlay P. , Lemouzy P. , Eschard R. , Zhang Li Rui
Published: December 2007

Decision of implementing two polymer-augmented waterflooding pilots in Daqing was taken in 1987 considering favorable laboratory results and preliminary reservoir studies. Since that date, the drilling of 8 injectors and 18 producers representing 4 inverted five-spot for each pilot has been achieved.

The formation is composed of different superimposed reservoirs. Each reservoir itself is constituted of numerous embedded sand and shale layers, characteristic of fluvio-deltaic deposits. Pilot PO is devoted to one reservoir while polymer injection in pilot PT will be simultaneously performed in two reservoirs which has been found to be more representative of injection conditions in Daqing. Oil viscosity is 9.5 cp.

Drilling was accompanied by an intensive program of data collection such as electric logging, coring, DST and interference tests. The paper presents how these data have been interpreted in terms of geological deposit to give the best possible vertical and areal description of each reservoir as well as their integration in the 3D chemical model SARIP designed by IFP. Polymer injected is HPAM at a concentration of 915 ppm.

The paper discusses the different results of simulation, focusing on fluid and polymer production profiles and areal distribution in each reservoir.

The predicted range of incremental oil recovery inherent in polymer is dependent on the severity of the reservoir heterogeneity and varies from 7.5% in stratified areas to 12% when the formation is more homogeneous. This indicates a better polymer efficiency to reduce the detrimental water-oil mobility ratio than to correct the rock permeability profile.

The paper ends by a presentation of the first field production results of the pilots that were put in stream in 1989.
First 12 Months’ Experience of Disconnectable Mooring System for H221/H226 FPSO
Authors: Davison Christopher , Wang Heng Qi , Holzle R. G.
Published: December 2007

The development of the HZ 21 and HZ 26 oilfields offshore People's Republic of China incorporates a tanker based FPSO. The FPSO is moored by means of a disconnectable mooring system which allows the FPSO to leave the site in the event of an approaching typhoon.

The mooring system is one of a novel design in which the mooring buoy floats below sea level when disconnected, and in the connected mode is joined to a turret in the tanker's forepeak. The system was commissioned during early September 1990, and this paper gives a description of the design, construction and installation of the system and resumes the experience gained during the first twelve months of operation.
Horizontal Well Operations at Prudhoe Bay
Authors: Broman W. H. , Schmohr D. R. , Schnorr D. R.
Published: December 2007

An evaluation of the current status of horizontal wells at Prudhoe Bay which focused on recent developments in the areas of well performance, surveillance and wellwork results has been recently completed. BP Exploration currently operates 17 horizontal wells at Prudhoe Bay. Their performance analysis is an integral component in the future decision processes of reservoir management and further drilling opportunities as the field matures.

Horizontal well performance data at Prudhoe Bay has shown an increase in oil production rate and accelerated recovery from a majority of the wells in comparison to offset vertical wells. The productivity of the horizontal wells is controlled by both the reservoir description and the well completion. Results from horizontal well workovers and stimulations have been varied. Analysis of the procedures employed has resulted in recommendations to follow in conducting future operations on horizontal wells. Case studies from two horizontal well workovers are included in this paper to highlight the risks, techniques and options available.

Horizontal well surveillance analysis is complicated by production logging tool limitations, horizontal multiphase effects and completion designs. Three production log analyses that illustrate the technical challenges associated with logging horizontal wells are discussed in this paper.
Evaluation of Loose Formations by Means of Constant Pressure Underbalance During Perforation Cleanup
Authors: Puntri P. L. N. , Ceci G. , Obondoko G.
Published: December 2007

This paper presents a case history of a technique utilized in a loose sand fontation to keep constant pressure underbalance during tubing fill-up after TCP shooting.

The method allows a good evaluation of the formation characteristics scon after the TCP shooting, providing an early knowledge of the formation productivity before the final completion with gravel-pack and Electric Submersible Pumps. Moreover, it gives the means for a correct pump design and the evaluation of the gravel pack efficiency.

This technique developed by Agip Recherches Congo was applied to shallow reservoirs consisting of loose sands filled with rather viscous oil. All the wells are completed with gravel packs and electric submersible pumps (ESP).

Prior to shooting the tubing is filled with nitrogen and the pressure is discharged to have desired under-balance. To keep underbalance constant during tubing fill up, WPH is discharged to decrease backpressure.

The fact that a practically constant pressure underbalance occurs during perforation clean up allows a reliable interpretation of the bottom hole pressure transient.
A Geostatistical Well Correlation Method That Can Identify Faults
Authors: Yang An-Ping
Published: December 2007

To effectively produce oil and gas from a reservoir we need to locate faults. A geostatistical method is developed to correlate wells mathematically to determine their relative stratigraphie alignment. With more than two wells the change in dip angle is used to identify a fault. Uncertainty can be reduced when more wells on both sides of the fault are included in the analysis. The major advantages of this new method are: (1) more data can be correlated at the same time to detect otherwise unidentifiable faults, (2) the analysis can be done quickly on a computer, and (3) the correctable range of well spacing can be determined from geostatistical theory with the variogram.
Wellbore Stability and Drilling Results From the First Horizontal Well in the Kotter Field Offshore The Netherlands
Authors: Fuh G-F. , Deom D. B. , Turner R. D.
Published: December 2007

This paper presents the method and analysis of borehole stability prior to drilling the first horizontal well located in Block K/18 of the Dutch Sector of the North Sea. Field data from eight previous wells drilled in the area were analyzed and used to construct a geomechanics model for numerical simulations of potential behavior of the horizontal well under design. The challenge was to drill a high-angle hole through the highly reactive and potentially overpressured Vlieland Shale, then into the partially depleted (6.8 ppg equivalent mud weight) underlying Vlieland Sandstone. Borehole stability analysis provided useful information for well plan and drilling considerations.

The horizontal well was a great success technically and economically. The excellent results can be attributed to prewell planning and good communications between operating personnel and associated service companies. In addition, drilling practices, adopted as a result of the understanding of borehole mechanics, helped overcome problems in borehole instability. Details of drilling and completion operations are included in this paper.
The Design of Steerable BHA's To Minimize the Adverse Effects of Motor Imbalance and Drilling Forces
Authors: Harvey P. , Wassell M.
Published: December 2007

Drilling forces from the bit, drill string and mud motor rotor imbalance adversely affect the performance of steerable bottom hole assemblies (BHAs). Proper BHA design can significantly enhance tool reliability and drilling performance. Positioning of stabilizers and the use of drill collar flex sections to minimize the effects of rotor imbalance are of particular importance when designing steerable BHAs.

Evaluation of the performance of steerable BHAs run in a 17-1/2″ diameter hole indicates that the evolution from low torque/high speed mud motors to high torque/low speed mud motors has introduced connection fatigue problems associated with increased response of the latter to mud motor rotor imbalance.

High torque/low speed motors are characterized by the use of multilobe rotors. These rotors orbit eccentrically about the center of the motor housing at speeds several times greater than the output shaft speed. This creates large cyclic imbalance forces which impart large dynamic loads onto the BHA.

Proper positioning of stabilizers and the use of flex-sections in the BHA reduce the adverse cyclic bending moment levels below those of the low torque/high speed motors, thus eliminating their contribution to connection fatigue.

In addition to critical mud motor imbalance loads, natural lateral frequencies must be considered in the BHA design in order to avoid bit bending and whirling excitations. Finite element modal analysis of the proposed BHA design can determine these critical speeds, as well as speeds that may result in undergauge stabilizers bouncing from side to side in the hole.
Bit Balling and Wellbore Instability of Downhole Shales
Authors: Ledgerwood L. W. , Salisbury D. P.
Published: December 2007

While oil-base muds have given satisfactory performance in the past, environmental concerns motivate the further development of water-base muds. Often associated with water-base muds are operational problems such as bit balling, high torque, and stuck pipe. Tests commonly used to evaluate muds are typically conducted on nonpreserved, unstressed shale and disparate formations. There is a need, therefore, for means of evaluating non-oil mud systems in the laboratory to predict relative performance under field conditions.

This paper describes two methods of testing water-base muds on preserved, stressed shale specimens. One test method utilizes the Microbit Drilling Rig (MDR) to study bit balling characteristics of shale in a given mud system. The test results showed that the clay matrix of the rock can influence balling. The type of cations present are critical, whereas cation exchange capacity and moisture content are not directly correlatable to bit balling. Analysis of the rock to determine composition and plasticity can be used to determine the tendency of a given formation to ball the bit.

The second method utilizes the Downhole Simulation Cell (DSC) to study wellbore instability resulting from exposure of shale to drilling muds under downhole temperature and stress conditions. An elasto-plastic model is presented showing how mud type can affect wellbore stability. These results caution against reliance on tests of unconfined shale particles (cuttings) or even unconsolidated shale specimens when studying effects of muds on shale instability.

Tests results from the MDR and DSC test equipment can be used to develop data bases for the selection of mud system and bit type and to suggest hydraulics to prevent balling of PDC bits. The data has been applied to the selection of a water-base mud that reduced both mud and operation costs when drilling deviated wells in the Gulf of Mexico.
A New Method for the Quantitative Determination of the PHPA Polymer Content of Drilling Fluids and Other Aqueous Systems
Authors: McCulley L. Z. , Malachosky E.
Published: December 2007

The need for a reliable, quantitative analytical method for the determination of the partially hydrolyzed Polyacrylamide (PHPA) polymer content, of drilling mud and other water-base fluids has been evident for some time. Previous methods have been based on either the precipitation of the anionic PHPA molecule or alkaline hydrolysis of the amide nitrogen to form ammonia. All these methods are semiquantitative determinations and are subject to a wide variety of interferences. Another severe limitation, in the case of drilling fluids, is that a portion of the mud filtrate is used for analysis. The free polymer content of the filtrate is rarely, if ever, the same as the unfiltered liquid phase of the whole mud.

The method described in this paper is truly quantitative and is an absolute rather then an empirical method. It is based on the total oxidation of all organic material in a sample of the liquid phase of a water-base drilling fluid. The amide nitrogen in the polymer molecule forms ammonium ions during the digestion and oxidation process. These ammonium ions are then measured with an ammonia gas-sensing electrode after conversion to ammonia by means of a simple pH adjustment.

In addition, a sampling technique has been developed which enables the analyst to obtain a solids-free portion of the liquid phase of a drilling mud sample without filtering the liquid through the mud filter cake. Thus, the method assures measurement of the available free polymer content of the fluid phase of the whole mud.

The method described is ideally suited to the determination of the PHPA content of any aqueous solutions including those encountered in wastewater treatment and sludge dewatering operations. The results of both laboratory and field evaluations of the method are presented.
Wellbore Fluids Model Provides Basis for Drilling Optimization
Authors: Swanson B. W. , Heritage J. R. , Lawsoh D.
Published: December 2007

Current drilling engineering applications programs generally consider only one aspect of the drilling process and therefore allow drilling optimisation in terms of only one variable. In reality, however, drilling is a highly complex and interactive process in which optimisation of one parameter in isolation can have significant and possibly detrimental effects on another.

This paper describes a novel computer program, the Wellbore Fluids Model, that allows a realistic replication of the interacting processes that occur as drilling fluid flows around the wellbore; these include, for example, cuttings transport, hydraulic pressures and fluid property changes with temperature and pressure. By considering these interactions simultaneously the model can provide a more realistic foundation on which to base engineering decisions to ensure optimum rate of penetration.

The paper provides a comparison of the model predictions against field measured data. A simulation which illustrates the complex interactions that occur whilst drilling is presented.
The EC Social Charter, Professional Standards, and New Engineering Entrants
Authors: Harnett Brian , Taylor Simon
Published: December 2007

The aim of this paper is first, to give a brief overview of the EC Social Charter highlighting its achievements to date and second, to focus on the Community’s attempts to harmonize the divergent national rules governing professional standards and the recognition of diplomas with emphasis on the engineering sector.

The Social Charter seeks to establish a code of fundamental social rights to be enjoyed by Community workers. However, it is no more than a political declaration of principles and intent. It has no legislative effect nor does it extend the legislative powers of the Community Institutions. Indeed it was only signed by eleven out of twelve Member States. The United Kingdom, under Margaret Thatcher’s intransigent leadership, refused to approve a document which it saw as an attempt by European socialists such as Jacques Delors, the President of the Commission and Vasso Papandreou, the EC Social Affairs Commissioner to introduce socialism "by the back door" thus undermining the U.K.’s duly elected conservative government.

Although the mutual recognition of diplomas and professional experience was listed in the Social Charter as a fundamental social right, it is easily distinguished from many of the other, more politically controversial, rights. It will be seen below that the central idea behind the Social Charter is to protect workers from the cut-throat capitalism of the free market system by creating a safety net of workers’ rights. Its opponents see it as a socialist threat to the success of the EC "single market" programme which is due to be completed by 1992. The recognition of diplomas is, on the other hand, a central aspect of the EC rules governing the free movement of persons in the Community. The Treaty of Rome, which is the constitution of the European Community, obliges Member States to ensure that persons, including workers and professionals, can move freely and establish themselves without hindrance anywhere in the Community. This principle, along with the free movement of goods, services and capital, is a prerequisite to the success of the EC "single market". The idea is that without this freedom of movement throughout the Community the desired pan-European economies of scale cannot be achieved. For example, an engineering firm, based in one Member State but wishing to branch out and operate throughout the Community, would suffer a commercial handicap if its engineers, qualified in the original Member State were unable to offer their professional services or be relocated in other Member States.
Flow Visualization of Viscous Fingering in Heterogeneous Porous Media
Authors: Brock D. C. , Orr F. M.
Published: December 2007

Flow visualization experiments and numerical simulations were performed to investigate the combined effects of viscous fingering and permeability heterogeneity in four different two-dimensional glass bead packs. In each model, unstable displacements were performed at three different flowrates and mobility ratios. The experiments were also simulated numerically, using a particle tracking simulator.

In the homogeneous model, fingers grew through the mechanisms of spreading, splitting, shielding and coalescence. Fingering patterns were sensitive to mobility ratio but not to flowrate. Analysis of pressure distributions in and around fingers showed that viscous crossflow drives the finger growth mechanisms.

In the heterogeneous models, flow was largely determined by the patterns of heterogeneity. In all experiments, flow followed high permeability paths seen in the Μ=1 displacements, with viscous fingering effects overlain, despite the fact that permeability contrasts were mild (four-to-one). Simulations yielded finger patterns remarkably similar to those seen in the experiments. Thus, the simulator used represents with reasonable accuracy the physics of finger growth in heterogeneous porous media.
Fair Market Value: Theory vs. Practice
Authors: Williams J.
Published: December 2007

This paper presents an examination of fair market value concepts as they pertain to producing petroleum properties. Conventional petroleum economic theories of fair market value are examined in light of recent work on the market value of long-life reserves. Their work is expanded to show that sellers rely on comparable sales data for estimating FMV. Both results are used to suggest that current practices over-emphasize the discounted cash flow approach to estimating fair market value.
A Statistical and Economic Analysis of Incremental Waterflood Infill Drilling Recoveries in West Texas Carbonate Reservoirs
Authors: French R. L. , Brimhall R. M. , Wu C. H.
Published: December 2007

This paper presents empirical infill drilling forecast models and infill well economics for Permian Basin Clearfork and San Andres waterflood units. Four infill recovery indicators were analyzed: 1) ultimate recovery, 2) incremental recovery, 3) recovery per well, and 4) recovery per acre-ft. It was estimated from these forecast models that an additional 6.9% OOIP or 710 MMSTB could be recovered by infill development to 10 acre well spacing in those units studied.

Infill recovery forecast models developed have waterflood recovery and fraction reduction in well spacings as independent variables. The forecast results match actual field data reasonably well. Reductions in well spacings seemed to play a more significant role in determining infill performance in Clearfork than in San Andres.

Economic analyses were performed on an infill well basis. Breakeven economic analysis was conducted for the first guantile reserve level of 70 MSTB and by varying initial production rates. A set of curves were generated for each formation as a quick reference.
A Comparison of Steam- and "Cold"-Gas-Foams in Terms of Thin Liquid Film Stability
Authors: Hatziavramidis D. T.
Published: December 2007

Generation and destruction of steam foam in porous media are governed by the stability of evaporating/condensing thin liquid films, with a surface active solute, in contact with the pore wall (wall films) and sandwiched between two liquid/gas interfaces (free films or lamellae), respectively. The surface tension at the film interface is allowed to vary as a result of temperature (thermocapillarity) and surface excess concentration gradients (surfactant effect). A comparison of evaporating/condensing films associated with steam foams to isothermal films associated with "cold" gas foams is made in terms of stability characteristics.
CT Imaging of Steam and Steam/Foam Laboratory Experiments
Authors: Demiral B. M. R. , Castanier L. M. , Brigham W. E.
Published: December 2007

The CT imaging technique together with temperature and pressure measurements were used to follow the steam propagation during steam and steam foam injection experiments in a three dimensional laboratory steam injection model. During the design period, the advantages and disadvantages of different geometries were examined to find out which could best represent radial and gravity override flows and also fit the dimensions of the scanning field of the CT scanner. As a result of this analysis a 3D rectangular box with dimensions 20x20x7.5 cm was constructed. This box simulates one quarter of a five spot pattern. Aluminum, Teflon™ and Fiberfrax™ were chosen as supporting and insulating materials. Teflon™ was placed between the porous medium and the aluminum shell so that the rate of heat transfer in the porous medium would be much faster than that in the aluminum during a steam injection run. During experiments, steam was injected continuously at a constant rate into the water saturated model and CT scans were taken at six different cross sections of the model. Pressure and temperature data were collected with time at three different levels in the model. CT pictures and three dimensional temperature distributions were compared and analyzed in terms of observed steam zone at each section. To do that, CT numbers within the scan section were used to determine the steam and water zones, and with the aid of x-ray pictures the position and propagation of the steam zone were determined. In addition, using the three dimensional temperature distribution measurements at the same times, steam displacement fronts could be drawn at the scan section locations. These pictures and drawings were used to compare the results obtained from classical temperature-pressure monitoring and from CT scans.

During steam injection experiments the saturations obtained by CT matched well with the temperature data. That is, the steam override as observed by temperature data was also clearly seen on the CT pictures.

During the runs where foam was present, the saturation distributions obtained from CT pictures showed a piston like displacement. However, the temperature distributions were different depending on the type of steam foam process used. During the experiment which included non-condensible gas (nitrogen) injection, the temperature distributions, contrary to the saturation distributions, still indicated the presence of steam override, although the override was reduced by the foam. However, when there was no nitrogen the temperature distributions followed the saturation distributions. This may possibly indicate that the nitrogen foam ahead of steam foam caused the difference between temperature and saturation distributions. These results clearly show that the pressure/temperature data alone are not sufficient to study steam foam in the presence of non-condensible gas.
A Laboratory and Field Injectivity Study: CO2 WAG in the San Andres Formation of West Texas
Authors: Prieditis J. , Wolle C. R. , Notz P. K.
Published: December 2007

Laboratory measurements of CO2 and brine injectivities in restored San Andres carbonate cores at reservoir conditions are reported. Included are results both with unsaturated CO2 and brine as well as with brine equilibrated with CO2 and CO2 equilibrated with brine. A waterflood, oilflood, and miscible flood followed by many cycles of CO2 and brine injection were done. Important results are the following: endpoint CO2 relative permeabilities were substantially smaller than both water and oil endpoint relative permeabilities making CO2 less mobile than would be anticipated just from viscosity ratios, the irreducible water saturation increased after an oilflood and persisted during subsequent CO2 floods, residual CO2 saturations to saturated brine were about the same magnitude as the residual oil saturations to waterflood, and the injectivity of unsaturated brine was much higher than saturated brine because of absorption of the CO2 phase.

The laboratory work was done in support of an injectivity field trial. The results of an injection of two cycles of CO2 and of brine into a well in the Mabee Field in the San Andres formation are reported. Both the CO2 and the brine field injectivities were significantly greater than the pre-CO2 waterflood injectivity on a volumetric basis. Field injectivities were somewhat greater than would be anticipated from the laboratory data. A simple analytical injectivity model could approximate some of the features of the field test but was not completely satisfactory.
Pore Combination Modeling: A Technique for Modeling the Permeability and Resistivity Properties of Complex Pore Systems
Authors: Myers M. T.
Published: December 2007

An empirical model is presented for the flow properties of rocks which is consistent with Archie’s equation1. The parameters for the important pore types for both elastics and carbonates are obtained from fits of measured formation factors to thin section point count data. These same parameters are used to model the saturation dependence and permeability.
Representation of Fault Sealing in a Reservoir Simulation: Cormorant Block IV, UK North Sea
Authors: Bentley M. R. , Barry J. J.
Published: December 2007

The representation of structural complexities in numerical reservoir simulations is cumbersome and often over-simplified. The introduction of leak paths across faults is particularly subjective, because patterns of fault sealing are generally not described by the geologist.

A procedure is presented here which models fault sealing capacity, and allows potential leak, paths to be located, ranked and incorporated into the simulation model. The procedure involves the semi-quantitative modelling of fault sealing assuming clay smear and shale juxtaposition to be the primary sealing mechanisms. The capacity for sealing along faults cutting representative reservoir sequences is described on clay smear ‘type panels’. Information from the type panels is used to map out variations in fault sealing capacity along individual fault planes, allowing potential leak paths to be located and ranked.

The reservoir simulation employs a coarse, curvilinear grid, designed to honour the structural configuration of the reservoir but facilitate fast processing times. Ranked leak paths are introduced into the simulation model during history matching to constrain cross-flow between reservoir

sub-compartments. This leads to a matched simulation model, and also provides a calibration of the fault seal model against production data.

The procedure of combining the reservoir simulation and fault seal models illustrates the benefits of an integrated production geology/reservoir engineering approach to reservoir modelling.
Testing of Horizontal Gas Wells in Anisotropic Naturally Fractured Reservoirs
Authors: Ng M. C. , Aguilera R.
Published: December 2007

Analytical solutions that include real gas pseudo pressures are presented for pressure drawdown and buildup analysis of horizontal wells in anisotropic reservoirs with tectonic, regional or contractional natural fractures. The reservoir might be limited by parallel sealed boundaries. The solutions have been obtained with the use of Fourier and Laplace transforms. Wellbore storage has been handled using a finite difference scheme of the convolution integral.

These solutions have led to the identification of the following flow periods: Wellbore storage which might mask many of the subsequent flow periods.A first radial flow period at early times from the natural fractures into the horizontal well. This occurs in a vertical plane.A transition period due to flow from the matrix into the natural fractures.A second radial flow period, still in a vertical plane, which starts when pressures in matrix and fractures reach an equilibrium. This pressure equilibrium can also be attained at a later flow period in which case the second radial period would not be present.A linear flow period when the pressure transient reaches the upper and lower boundaries of the reservoir.A pseudo radial flow period towards the wellbore in a horizontal plane.A linear flow period when the pressure transient reaches the outer parallel boundaries.

It is concluded that recognition of these flow periods can lead to calculation of pi or p*, permeabilities in the x, y and z directions, storativity ratio omega, average distance between natural fractures, fracture porosity, fracture aperture, skin, and pseudo skin due to vertical and horizontal partial penetration. Calculations are illustrated with an example.
The Geological Modeling of Effective Permeability in Complex Heterolithic Facies
Authors: Norris R. J. , Lewis J. J. M.
Published: December 2007

Conventional methods of quantitative reservoir characterization are inappropriate when confronted with the complex ripple-scale (millimetric to centimetric scale) intercalations of sand and shale that are characteristic of heterolithic facies. This paper presents a new methodology for quantifying single-phase fluid flow behaviour in heterolithic facies by defining, for discrete heterolithic lithofacies types, effective permeabilities at Representative Elementary Areas (REAs). REA graphs are defined by calculating effective permeabilities at increasing scales, using the renormalization approach. Given that effective permeability values in these facies are dominated by sand connectivity, these REAs are based on binary sand-shale indicator maps derived from constant-scale photography at outcrop. The heterolithic facies studied produce REAs at characteristic scales of around 20,000 cm2. REA based effective permeabilities in different directions show comparable areal dimensions, but significantly different permeability values. REA based effective permeabilities can subsequently be modelled in inter-well volumes through the use of various indicator based pattern recognition procedures. A methodology is presented for developing realistic "training" patterns of heterolithic lithofacies through outcrop photography.
Fast Generation of Grid-Block Permeabilities for the Analysis of Uncertainty on Reservoir Simulations
Authors: Gomez-Hernandez J. J. , Journel A. G.
Published: December 2007

Monte-Carlo analysis of uncertainty on reservoir performance is very expensive. It involves: first, the generation of multiple permeability fields at the scale of the measurements; second, the average of these permeabilities to obtain equivalent grid-block permeabilities at a scale that can be handled by current numerical reservoir simulators, and third, the simulation of flow on these scaled-up fields. Although the most expensive step is, generally, the third one, there is still time and effort invested in the first two steps. An approach is proposed for the fast generation of equivalent grid-block permeabilities directly from the measurements honoring both local information and structural information. The approach is based on a geostatistical model for the joint spatial variability of both measured permeabilities and grid-block permeabilities.
Modeling Geological Heterogeneities and Its Impact on Flow Simulation
Authors: Suro-Pérez V. , Ballin P. , Aziz K. , Journel A. G.
Published: December 2007

A single algorithm is proposed for the numerical modeling of geological facies and corresponding petrophysical properties. All reservoir parameters, whether categorical such as lithofacies type or continuous such as permeability are coded and processed as a series of binary indicator variables. Stochastic modeling of the reservoir is based on Indicator Principal Component Kriging and the sequential simulation principle. The resulting alternative and equiprobable reservoir models honor the available information at wells and their statistics. These reservoir models are then used to investigate the impact of geological heterogeneities on flow performance prediction in a water-flood scheme. Analysis of various production parameters (cumulative oil production, cumulative water oil ratio and breakthrough times) indicates that they are more sensitive to the geological architecture of the reservoir than to details of the statistical distributions of petrophysical variables. Direct modeling of permeability across lithofacies, i.e. ignorance of the geological architecture, may lead to severe inaccuracy in reservoir performance prediction, particularly after the first transient years of production.
The Effect of Large-Scale Heterogeneities on the Performance of Waterdrive Reservoirs
Authors: Barthel R.
Published: December 2007

A significant fraction of the reservoir volume may remain unswept during a water-oil displacement. Potentially recoverable oil in a clastic reservoir may be bypassed as a consequence of poor sand connectivity or large contrasts in permeability between neighbouring sandbodies. Such conditions typically occur in fluvial deposits (poor connectivity) and channel-fill/mouthbar combinations (large permeability contrasts).

To investigate the effect of the properties of these reservoirs on waterdrive efficiency, simulations of prototype reservoirs have been carried out. All waterdrives investigated were flank waterdrives, representative of North Sea reservoirs.

The reservoirs characterised by sandbodies with different ranges of permeability could be modelled with a relatively coarse grid. The effects of sandbody geometry, well spacing and permeability contrast on the displacement efficiency were investigated. It was found that in some cases the additional recovery from an infill well, located in a poorly swept, low-permeability sand, can be as high as 7% of the STOIIP contained between the initial wells.

Modelling the complicated networks of channel sands surrounded by shales encountered in fluvial deposits requires a much finer grid with a larger number of gridblocks than modelling large sand bodies. To accommodate simulation models with a large number of gridblocks a highly simplified special-purpose simulator was developed. This simulator neglects those physical mechanisms that have only a minor effect on the displacement process considered and can handle models with more than 100 000 gridblocks easily. For these fluvial reservoirs the effects of channel density, alternative channel distributions (reservoir architecture) and of permeability contrasts between channels were investigated. It was found that at low channel densities (average nett-to-gross ratio less than 25%), oil tends to be bypassed because of poor connectivity and that the overall performance depends on the reservoir architecture. At higher channel densities, permeability contrasts can be a major cause of bypassing.
Energy Resources Engineering - A New Concept In Engineering Education
Authors: Schoeppel R.J. , Comer A.G. , Rowe A.M. , Sebesta H.R.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

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.

To meet present and future competition, many oil companies are expanding their operations in the direction of becoming totally integrated energy companies. Their activities range from exploration and development of petroleum reservoirs, tar sands and oil shales, to diversification in energy associated industries such as those producing coal or nuclear fuel. In light producing coal or nuclear fuel. In light of these developments, the public image of an "oil company" is changing from strictly a petroleum alignment to one that is concerned with the nation's overall energy requirements and uses.

Petroleum engineers are well trained to exploit conventional petroleum reservoirs; however, the development of the additional sources of energy now will require engineers with a different type of training. In order to provide for these new technical manpower needs, a program has been developed at Oklahoma State University that integrates all of the energy related aspects of the various classical engineering fields into one discipline. This new concept in education, called Energy Resources Engineering, encompasses training in the production, processing, conversion, transportation, processing, conversion, transportation, storage and utilization of energy. It is the purpose of this paper to review the development of the program in Energy Resources Engineering at OSU and to present a discussion of experiences gained during its first two years of operation. Early student reaction to this course of study has been favorable.

Introduction

Because all mankind is involved in a dynamic technological advance the comparison of which have never been seen before, nations that have been able to exploit their natural energy resources have made tremendous strides in raising their standard of living. In the United States the rate of advance is especially high where the rising affluence coupled with greater public demand for more and better products and services is transcending rapidly its citizens into a high energy-consumming civilization. The rest of the world is following closely behind our nation in this.

Since energy is required in order to do work, obviously the availability of large quantities of inexpensive energy and the efficiency of its conversion has been fundamental to increased productivity and economic progress.