bluuebunny/crossref_metadata_2025 huggingface dataset:
Drilling and Production From a Floating Spar
Authors: Brooks I. H. , Carroll J. P.
Published: December 2007

A deepwater drilling and production platform has been designed based on a floating spar. The spar is a catenary-moored cylindrical vessel having a deep draft which minimizes heave motions. The concept is an economic competitor with other deep water designs such as compliant towers and tension leg platforms. The spar's oil storage capacity makes it particularly applicable for remote areas where pipeline infrastructure is unavailable and production is primarily from oil reservoirs. Without the need for a swivel, offloading of oil can be accomplished either directly from the spar, by use of a floating hose and support vessel, or by transfer to an offloading buoy. The concept is compatible with early production or phased development scenarios, permits surface completions of producing and injection wells, and allows for direct well intervention. The ability to reposition the spar by manipulations of the mooring lines favors a system of individual wellheads on the seafloor. Wells can be drilled, completed, and produced without pulling the drilling riser. When production from the field reaches its economic limit, the entire system can be towed to a new location and reused.
Fracture Relative Permeability: Linear or Non-Linear Function of Saturation
Authors: Pieters D. A. , Graves R. M.
Published: December 2007

The definitive work on fracture relative permeability was performed by E.S. Romm in 1966. His research concluded that relative permeability is a linear function of saturation. Since that time very few attempts have been made to calculate relative permeability in fractures. This paper presents the results of an independent experimental investigation to test the validity of Romm's results. The research was conducted with the same kerosene and water systems in a parallel glass plate fracture applying modern day techniques.

The technique of videoimaging was used for measuring saturations in the fracture. Relative permeability ratios were computed using Welge's interpretation of the Buckley-Levrett theory after fractional flow was obtained from the displacement.

Results indicated that relative permeability is not a linear function of saturation as was shown in the past.
Akal Field (Cantarell Complex) Conditions of Exploration, Analysis, and Prediction
Authors: Rojas A. G. , Torres A. R.
Published: December 2007

This paper presents a detailed description of the current conditions of explotations in the Akal Field (the most maximum producer in Campeche Sound and Mexico Country).

The Akal field, naturally fractured reservoir, began his explotation in june/79 with the well Akal-IA and 34,000 BOPD of production about 22° API. The field development was gradually and in the middle of 1981 had 40 producer wells, now the field counts with 140 wells and 890,000 BOPD of production with 7500 BOPD per well in average and cumulative production of 4647 MMSTB, thus we can classify like supergiant reservoir.

This field has a good condition for the gravity drainage mechanisms like thickness about 2300 feet, high permeability around of 3-4 Darcy and top reliev about of 6000 feet.

It's important to mention that this field has a gas-cap which has been increasing from 1981, now at may/94 the gas-oil contact is at 5719 feet and we establish a continuos monitoring with TDT logs. Based in this monitoring is possible to predict workover and recomennd infill – drilling.

Finally, we show the match and prediction behavior of the gasoil contact through the time and different explotation alternatives done with volumetric model.
Automatic Optimization of Well Locations in a North Sea Fractured Chalk Reservoir Using a Front Tracking Reservoir Simulator
Authors: Rian D. T. , Hage Asmund
Published: December 2007

A numerical simulator is often used as a reservoir management tool. One of its main purposes is to aid in the evaluation of number of wells, well locations and start time for wells. Traditionally, the optimization of a field development is done by a manual trial and error process. In this paper, an example of an automated technique is given.

The core in the automization process is the reservoir simulator Frontline. Frontline is based on front tracking techniques, which makes it fast and accurate compared to traditional finite difference simulators. Due to its CPU-efficiency the simulator has been coupled with an optimization module, which enables automatic optimization of location of wells, number of wells and start-up times.

The simulator was used as an alternative method in the evaluation of waterflooding in a North Sea fractured chalk reservoir. Since Frontline, in principle, is 2D, Buckley-Leverett pseudo functions were used to represent the 3rd dimension.

The areal full field simulation model was run with up to 25 wells for 20 years in less than one minute of Vax 9000 CPU-time.

The automatic Frontline evaluation indicated that a peripheral waterflood could double incremental recovery compared to a central pattern drive.
Increment on the Efficiency of the Drilling and Completion Operations of Marine Region
Authors: Zamora C. R.
Published: December 2007

The present work shows an outline of the activities of Management of Drilling of Wells of the Marine Region carried out in 1993, in comparison with former last years (from its beginning in 1974), in which different proposals arise to increase the efficiency of activities such as: -Drilling by administration-Incentived drilling-Turnkey-Filial with the integral maintenance of drilling

Alterning and competing this way with International parameter and statistic data given by specialty companies allowing it to reveal the human resources, technical and administrative that Petroleos Mexicanos possesses.
Creating World Class Exploration and Production Processes: A Practical Guide for Implementing Process Change
Authors: Goldthorpe W. H.
Published: December 2007

This paper describes the prerequisite elements for successfully achieving process change and improving process effectiveness. As with any major project, there are defined steps including planning, implementation, control and review. Once changed, process performance must be measured and controlled, and quality assurance used to ensure it's integrity is maintained.
Production Performance of a Retrograde Gas Reservoir: A Case Study of the Arun Field
Authors: Afidick Deddy , Kaczorowski N. J. , Bette Srinivas
Published: December 2007

The Arun field is one of the world's giant retrograde gas reservoirs. Approximately 10 years after production began, a significant loss in well productivity occurred in some of the wells. The study shows that this productivity loss was due to near wellbore condensate accumulation, and documents its effects on production and pressure transient response.

A radial, single well, compositional model was used to study this effect and confirm that the productivity loss was due to liquid accumulation. The model was also used to predict the future performance of the well. The model matches well production data and the pressure transient response of affected wells.

This work identifies near wellbore condensate accumulation as an extremely important factor to consider when predicting future well performance as some of the productivities are reduced by 50%. The work also details how production data and well test analysis can be used to quantify the effects of near wellbore condensate accumulation on well productivity.
Determination of Relative Permeability from Well Testing in Multi-Layer Reservoirs
Authors: Jatmiko Wahyu , Daltaban T. S. , Archer J. S.
Published: December 2007

This work investigates the use of non-linear programming approach to solve the non-linearity problems arising in stratified commingled reservoirs containing multi-phase fluid. The objective is to determine the relative permeability curves of each layer. This work uses a deconvolution method to handle multi-variable rate, which enables the determination of the layered reservoir properties. To calculate the effective oil permeability, this work proposes a polynomial curve fitting to represent the whole pressure response of the drawdown test. Therefore, smooth and continuous effective permeability curve can be expected. Three case studies are presented. The data are obtained from simulated drawdown tests.
Developing Effective Environmental and Oil Spill Management for Remote Locations
Authors: Smith J. P. , Wardrop John , Kilborn Anna
Published: December 2007

Historically, Exploration and Production (E&P) operators’ environmental philosophy was a consequence of environmental damages, actual and perceived, caused by hydrocarbon spills. Pertamina/Maxus Southeast Sumatra, Inc. (Maxus), the largest offshore E and P operator in Indonesia has adopted a proactive philosphy as we operate offshore production and shipping facilities immediately adjacent to the Pulau Seribu (Thousand Island) National Marine Park and approximately 30 kilometers from the Southeast Sumatra coast. These ecosystems are of great concern to Indonesia and Maxus as they comprise approximately 250 km of tropical, sparsely inhabited coastline, 106 coral and lagoon islands, and habitats for numerous endangered species.

This paper describes the contract zone within which Maxus operates; the environmental risks associated with E&P in this region; and Maxus’ response to management of those risks. A significant component of Maxus’ overall response has been the ESACOC project (Environmental Sensitivity and Characterisation of Crude) undertaken during 1993. ESACOC is described here in regard to the use and interrelation of remote sensing, in-depth laboratory studies, and development of new sensitivity rankings techniques into one computer program for effective eilvironmental and oil spill management. ESACOC illustrates the synthesis of seemingly diverse and unrelated data to develop an effective environmental management plan.
Griffin Area Subsurface Development Planning, Implementation, and Production Performance
Authors: Curtis A. A. , Mills P. A. , Nichol S. T.
Published: December 2007

The Griffin Area Development in the Barrow Sub-basin offshore Western Australia consists of three oil fields; Griffin, Chinook and Scindian, tied into the Griffin Venture Floating Production Storage and Offloading (FPSO) facility. First production commenced in January 1994, and the field is currently producing 12,700 m3/d (80,000 stb/d) of oil from up to nine available wells. In addition, associated gas is being piped onshore to provide up to 1.1 × 106 m3/d (40 million scf/d) of gas and 62.8 t/d of LPG.

Oil is found in the Lower Cretaceous sediments of the Zeepaard and overlying Birdrong Formations, with the Birdrong Formation at Chinook and Scindian having gas caps. The Zeepaard reservoirs have excellent reservoir properties and are expected to yield a high recovery through six vertical wells. The Birdrong Formation is unconformably deposited above the Zeepaard Formation, and is a lithologically complex mixture of sands with intermixed clays and shales and is generally of much poorer quality than the Zeepaard Formation.

The Birdrong Formation has provided some of the main challenges in the development, resulting in the implementation of three sinuous horizontal wells to access the better quality layers of the formation. Permanent downhole gauges have been used to assist in the determination of pressure support both in the Birdrong and Zeepaard Formations.

This paper outlines the key factors which shaped the Griffin Area Development Plan, details the implementation of the subsurface aspects of the Phase I development, and presents key aspects of reservoir performance to date.
Engineering Aspects of Preparation of Construction and Operation Agreements for Gas Facilities
Authors: Holland Charles J.
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Contracts for ownership and operation of joint interest gas handling facilities and processing plants are called as a class, processing plants are called as a class, Construction and Operation Agreements. These contracts seek agreement among the parties on the definition of EQUITY and provide contractural mechanics to achieve this EQUITY. The engineers' participation on a contract task force appears in participation on a contract task force appears in four general areas of the agreement: Definitions, Ownership Parameters, Distribution of Costs and Expenses, and allocation of Production and/or Services. The objective of the paper is to acquaint those engineers called to such task force duty with the problems to be anticipated and solutions devised by existing contracts in the Southwest.

Introduction

Every engineer engaged in the production of petroleum at sometime in his career finds himself enmeshed in the toils of Joint Operation. It follows, therefore, that the engineer should familiarize himself with the fundamental types of joint operating contracts. Most familiar are those agreements creating field unitization operations, for which there are numerous references in the literature. Another class of legal document is the contract most commonly associated with the joint interest operation of gas plants and facilities. Such a document is generally known as a Construction and Operation Agreement, or briefly, the C and O. This paper covers four major areas of this contract calling for an engineer's attention.

OWNERS SEARCH OUT EQUITY

Before proceeding to the areas, we should review some of the thoughts and theories underlying and leading to the formation of the C and O. Contracting owners, seeking to choose one of themselves to construct and operate a facility, have before them certain goals: first, to develop a definition of "Equity" for the situation; second, to construct a mechanism to achieve and maintain this defined "Equity;" and third, to preserve for the contract life a factor I call "effective timelessness." By this last, I mean the ability of the contract to maintain current applicability for two decades with respect to depleting reserves, changing owners, major construction additions, changed process, and on, ad infinitum. The contracting process, and on, ad infinitum. The contracting owners most usually work through their appointed individual agents, who serve on an owners committee and have various degrees of owner authority. (For the purpose of this discussion, we shall consider the agent and the owner to be synonymous.)
A Synergistic Approach to Optimizing Hydraulic Fracturing
Authors: Kessler Calvin , Venditto Jim , McMechan David , Edwards Peter
Published: December 2007

Combining measurement, simulation, and imaging technologies into an integrated program can help operators achieve the best hydraulic fracture treatment possible. Hydrocarbon production can be significantly increased when fractures are extended to the planned length, and fracturing fluid is retained within the zone of interest. Fractures that break out of zone increase the risk of excess water production with the hydrocarbon. Consequently, the ability to select suitable operational parameters for hydraulic fracturing is critical to job success.

An evaluation of formation properties and potential barriers to hydraulic fracturing can be made with three-dimensional(3D) simulation to integrate data taken from wireline logs, waveform sonic logs, and microfrac measurements. In-situ stress orientation is determined by use of a downhole extensometer, oriented cores, anelastic strain recovery (ASR) measurements, and borehole imaging logs.

Sidewall cores can be taken perpendicular to wellbore walls without distorting the borehole or the core taken; orientation of the cores can be determined with imaging logs run after coring. Natural fractures can be viewed with a downhole video camera lowered into the well on fiberoptic cable.

Effectiveness of fracture treatments may be evaluated with various gamma ray logging techniques and production logs comparing expected production to actual zonal contribution. Refined procedures that result from after-frac analysis can be used to plan field development for optimal reservoir drainage.
Temperature Field Measurements and Computer Program Predictions Under Cementing Operation Conditions
Authors: Merlo Antonino , Maglione Roberto , Guillot Frederic , Bodin Dominique
Published: December 2007

During cementing operation it is important to have a good control of the setting time. The setting time is strongly affected by the wellbore temperature. So circulating temperature is one of the most important parameters for the design of cementing operations.

In order to better control this parameter, measurements were performed on a deep well in cased hole.

Temperature were measured at different depths on a deep vertical well with a 7" tie back casing in hole before and during mud circulation, in order to accurately estimate the temperature profile in the well. Very few data have been published in the literature with casing in hole.

The circulating measured temperatures are compared with calculated temperatures by means two computer programs, developed by two different Companies.

It is shown the good agreement for each depth between the field measurements and the calculated results. This field case can be used as a base for the validation of the other temperature computer programs.

A description of the analytical model of the computer programs is presented in the paper.

The computer program calculates the temperature profile of the fluid in the casing, in the annulus and in the formation for each measured depth of well during circulation.

The heat exchange between the casing, the annulus and the formation is described by means of integration of the equations of conservation of energy, applied to a control volume inside the casing, the annulus and the formation.

Some justified assumptions are made to obtain the desired partial differential equations...,

Some correct boundary and initial conditions are defined for the solution of the differential equations of energy.
Relative Permeability Measurements: An Inter-Laboratory Comparison
Authors: McPhee C. A. , Arthur K. G.
Published: December 2007

Evaluation of the comparative performance of four service contractors has highlighted often inexplicable inconsistencies and discrepancies in laboratory waterflood data, despite using similar test cores, identical test fluids, and similar test procedures. Depending upon the methods laboratories prefer to establish initial water saturation, and their favoured waterflood rates, the difference between oil initially in place and residual oil saturation varied from 10 to over 60 saturation units. Duplicate tests carried out by the co-ordinating laboratory failed to replicate two laboratories’ results, and showed that both residual oil saturation and relative permeability are rate-dependent, but relative permeability appeared to be viscosity-independent. Although low rate "bump" floods might yield appropriate end-point data for water-wet rocks, virtually all laboratory waterfloods invalidate classical interpretation theory. Analytical models must therefore allow for capillary pressure, wettability, heterogeneity and viscous instability. Recommendations on the key steps in representative laboratory core flood test design include appropriate wettability conditioning, initial water saturation, selection of viscosity ratio and flow rates, and quality control procedures.
Simultaneous Determination of Capillary Pressure and Relative Permeability of a Displaced Phase
Authors: Kokkedee J. A.
Published: December 2007

A procedure is presented for the simultaneous determination of capillary pressure and tail-end relative permeability from a continuous injection experiment at different flow rates. This is achieved through matching the experiment with numerical simulations. In our experimental setup, a core plug is placed between a water-wet and an oil-wet filter while fluid is injected continuously into the core. The resulting pressure drop over the core contains information on both the capillary pressure and the relative permeability of the displaced phase. With an optimisation procedure, built around a numerical simulator, these key reservoir parameters can be extracted from the measured differential pressure. The validity of the procedure is discussed and whether the capillary pressure and relative permeability curves obtained are unique is examined. Application of the procedure to sandstone, provides results which are in good agreement with those obtained with other techniques. The automatic matching procedure developed can, in principle, be applied to every experiment that can be simulated with a standard simulator. As an example, the calculation of the capillary pressure and tail-end relative permeability from equilibrium centrifuge data is discussed.
Accurate Insitu Compositions in Petroleum Reservoirs
Authors: Fevang Øivind , Whitson Curtis H.
Published: December 2007

This paper describes experimental procedures for determining accurate estimates of original insitu reservoir oil and gas compositions. The proposed equilibrium contact mixing (ECM) method can use samples which are clearly not representative of insitu fluids (e.g. due to nearwellbore multiphase behavior, reservoir depletion, or separator sampling problems). ECM procedures are recommended for saturated, undersaturated, and depleted reservoirs.

Examples are given for reservoir fluids ranging from very lean- gas/black-oil systems to highly volatile gas/oil systems. Furthermore, it is shown that the proposed ECM method can be used to obtain depth-weighted average insitu compositions in reservoirs with gravity- induced vertical compositional gradients.1

The Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) equations of state (EOS) are used in calculations, with extensive characterization of the C7+ fractions. Static PVT experiments and radial 1D/2D compositional simulations of typical fluid-sampling conditions are used to verify the proposed methods.

Partly due to the success of the ECM method, the traditional definition of a "representative" sample is reconsidered, and a more general definition is recommended. The general definition ("reservoir-representative") is any sample produced from a reservoir, where the measured composition and PVT properties are of good quality. The traditional definition ("insitu representative") is a special case where the sample represents an insitu reservoir composition at a specific depth (or an average composition for a depth interval).

Separator sampling of gas condensate and volatile oil reservoirs is widely used. We present an analysis of traditional separator sampling methods, potential errors in separator sampling, and a critical evaluation of the "isokinetic" sampling method. Isokinetic sampling is currently used to sample separator gas streams when separator liquid "carryover" is suspected. Problems with the isokinetic method are discussed, and we suggest field and laboratory measurements which are needed to confirm the validity of isokinetic sampling.
Development of a Thin Oil Rim With Horizontal Wells in a Low Relief Chalk Gas Field, Tyra Field, Danish North Sea
Authors: Nykjaer Olav
Published: December 2007

This paper presents the history of the development of an oil rim in a chalk gas field. In a low relief gas field, oil rim development is problematic because the proximity to fluid contacts leads to gas and water coning and a significantly decreased oil production. This problem has been reduced in Tyra by developing the oil rim with horizontal wells. The best oil wells are in areas where gas production is impaired by tight chalk immediately above the gas-oil contact, and where the oil rim Is thickest.

The field was initially developed as a gas field due to poor production tests of the oil rim during the appraisal of the field. An understanding of the distribution of oil led to the drilling of a successful oil rim well. The advent of horizontal drilling increased the scope for oil rim development and accelerated the drilling of oil rim wells. Extensive reservoir simulation work provided the reservoir management tool for the planning of an oil rim development under the constraint of a gas sales agreement. H has resulted in a plan for further development of the Tyra gas field. According to the plan additional gas Injection will in a period of seven years result in low net annual gas off-take from the Tyra gas production wells and the main production will instead come from horizontal wells in the oil-rim. During this time the majority of the oil reselrves will be produced.
Risk Assessment and Management in IOR Projects
Authors: Goodyear S. G. , Gregory A. T.
Published: December 2007

The application of IOR techniques is one of the investment opportunities open to Exploration and Production companies. A project will only go forward if the perceived balance between the rewards and the risks is acceptable. IOR projects may be ruled out because they are considered to involve significantly higher risks than conventional developments. Therefore, some means of evaluating the actual level of risk may be required if the full economic benefits from IOR techniques are to be realised.

Risk assessment is a key element in safety cases, where a well-established methodology for quantifying risk exists. This paper discusses the extension of these methods to IOR project risk assessment. Combining reservoir and IOR technique uncertainties with their impact on project performance allows project risk to be better quantified. The results of the risk assessment are presented in terms of a "risk-reward" diagram that plots the probability surface for possible project outcomes as a function of NPV (reward) and exposure (risk).

The outcome of a risk assessment can be used proactively to mauage risk by identifying actions to reduce the probability of project outcomes with low NPV and high exposure. Risk management strategies are identified, including improved project design, key data acquisition and contingency planning. It is argued that IOR projects should be optimised by considering economic and risk factors together.

A generic polymer project is used to illustrate the application of risk assessment and risk management techniques. A superficially attractive unrisked project is shown to be unacceptable when a risk assessment is performed However, by applying risk management and changing the project design appropriately, it is possible to achieve significant risk reduction with little loss in economic performance, compared to the unrisked base case project.
Reconciliation of Field Observations in a North Slope Reservoir Through Pore Fluid Microvisualisations
Authors: Gamble I. J. A. , Butler D. C. , Sinock K. J.
Published: December 2007

Log data from a North Slope field indicated particularly high initial water saturations in the major reservoir zone, often in excess of 50%. Despite this, well tests yielded dry oil from the producing intervals, implying that the mobility of the connate water was negligible. A pore fluid microvisualisation technique was used to examine the initial distributions of fluids within core samples, in order to reconcile the apparent inconsistencies in the field observations.

The amount and distribution of initial water was controlled by the proportion of micro-porosity. Connate water resided primarily within chert, although some was associated with pore-filling kaolinite. This clay mineral was partly water filled and partly oil filled, depending upon the capillary pressure applied to the core sample to acquire Swi. Very little water was held in a conventional manner as thin films on quartz surfaces. Core flow tests confirmed that mobility of water was essentially zero, even at the highest water saturations.

The technique was also used to examine the distributions of fluids at waterflood residual oil saturation. The rock was predominantly water wet in character and classical 'snap-off of residual oil was observed, with the oil being trapped as isolated 'blobs' or as multi-pore 'ganglia'. Saturation and distribution of oil after waterflooding was found to depend upon the flow rate and flow regime used.

Microvisualisations provide a unique insight into fluid distributions at Swj and Sorw. For this reservoir renewed confidence in saturations derived from well logs was realised.
Assessing the Relative Permeability of Heterogeneous Reservoir Rock
Authors: Jakobsen S. R. , Ingsøy Pål , Braun Ted , Guo Ying , Aga Magnar
Published: December 2007

Reservoir engineers are often faced with heterogeneous core material, for which conventional methods of estimating relative permeability are susceptible to error and may lead to incorrect conclusions regarding displacement efficiency, wettability and reservoir performance. This paper focuses on new techniques for judging the validity of relative permeability data obtained on heterogeneous cores.

Numerical simulation is used to quantitatively analyse the impact of typical heterogeneities. For unsteady-state tests analysed by conventional methods, it is shown that typical heterogeneities influence relative permeability in a systematic way, and that parts of the measured curves still may provide valid data. The error introduced by heterogeneities is quantified and correlated with the Dykstra Parson coefficient. Further, it is shown that the steady-state technique is more robust than the unsteady-state measurements in case of stratified material.
SCR-Based Feed Control Enables 100% Core Recovery in Slim-Hole Wildcats
Authors: Spoerker H. F. , Dhindsa J. S.
Published: December 2007

As part of a multi-year slim hole drilling project in Venezuela, large scale automization of the drilling/coring process has been achieved. An SCR-based constant feed control system has been implemented and proven to be a distinct advantage over standard weight-on-bit (WOB) oriented controls. The rather abrupt feeding when trying to hold WOB constant resulted in feed-off cycle frequencies of approximately 1 s -1 propagating through the drill string and thus inducing core breakage and jamming in the core barrel.

To avoid these axial peak loads, the system has been modified to feed off at a constant, driller-defined rate, slowing down gradually from this rate when approaching pre-set WOB maximum limits. This results in the drill string smoothly "following" the core head drilling off, allowing the core to continuously travel up the inner core barrel. Even laminated formations with ROP variations between <10 and >40 ft/hr were successfully drilled without core jamming and sustained 100% core recovery. Using this system, the driller can match bit and formation characteristics for a given rotational speed to achieve optimum ROP at reduced bit wear.

The system is completely based on the control of the drill string movement using the drawworks' DC motors and SCR system drive, thus eliminating the need for additional sensors in the derrick. It can be retrofitted to any SCR driven rig at low cost in minimum time. It's application is specially suited for slim hole drilling where the constant, smooth feed limits WOB fluctuations to only +/− 200 lbs, but can be used during any drilling operation, improving drilling performance and extending the service life of downhole equipment. This paper describes the technical realization of the system, its application during 4 1/2 inch coring operations and recommendations how to use it for optimum drilling performance and core recovery
Use of Uncertainty Techniques to Determine Input Parameters for a Gas Sweetening Plant
Authors: Comer A.G. , Campbell John M. , Menzie Donald E.
Published: December 2007

This paper was prepared for the Gas Industry Symposium of the Society of Petroleum Engineers of AIME, to be held in Omaha, Nebr., May 21–22, 1970. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. 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.

A primary consideration of an engineer in the selection or design of a gas processing unit is its capacity and its processing unit is its capacity and its sales volume. If only one source of gas of a uniform composition is available, the input parameters to the unit are fixed within very narrow limits. However, if two or more sources are commingling the gas supplied to the unit, then the designer is forced with the difficult decision of ascertaining the correct input parameters to use as design criteria. The authors of this paper found that the use of the principles of uncertainty would give the best engineering estimate to this latter case.

To illustrate the use of uncertainty techniques for this application, the authors' wrote a Fortran IV Computer program utilizing the Monte Carlo method. Several hypothetical problems are presented and solved. problems are presented and solved. In each example, the classical approach or using a straight volumetric calculation gave values for the acid gas composition which, if used without modification, would have resulted in an underdesigned unit. In each of the examples investigated the acid gas composition for each supply source was allowed to follow a normal distribution in order to compare the differences involved in this particular assumption.
Numerical Coning Applications
Authors: Coats K.H. , Henderson J.H. , Modine A.D.
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

This paper discusses the effect of completion interval on aquifer storage operations. The study was performed using a single-well, two-dimensional reservoir simulator model.

Results are presented for two reservoir geometries, a homogeneous and a highly stratified heterogeneous reservoir model. For both geometries, the effect of completion interval upon such parameters as water arrival time, injectivity and productivity indices, and gas bubble thickness were studied for two different rate schedules. Results showed that completion interval did not affect bubble thickness for the homogeneous model, but did show some effect for the heterogeneous model. For both models the depth and length of completion interval did affect such parameters as water arrival time, water parameters as water arrival time, water cut and productivity indices.

Introduction

Well completion intervals and depths used in aquifer storage operations frequently consist of five or ten feet perforated intervals located immediately below the caprock. In some cases the gas bubble thickness as estimated from neutron logs seems to stabilize or at least grow very little from year to year when thickening would be expected due to gravity drainage and/or inventory growth during the early life of the storage operation.
The Use of Integrated Software for Improved Reservoir Management
Authors: Dria M. A. , Avonstam Peter
Published: December 2007

Recent geoscience and engineering software developments, and 3-dimensional visualization in particular, ease construction and utilization of detailed geological descriptions in reservoir simulation. This enhances the interaction between asset team members such as geophysicists, geologists, petrophysicist, reservoir engineers, and production engineers, and provides the media to share concepts, data, and ownership in the creation of a consistent geo-engineering model. This paper provides insight into what is software integration, what are the current industry trends, and how software integration impacts the way reservoir studies are conducted. Advantages of integrated software in reservoir management are both technical and timesaving in nature. These advantages are discussed. Examples of integrated studies provide background material for the discussion of these questions. The authors also discusses the many remaining challenges the geoscience/engineering software industry faces and how it must respond in meeting these challenges.
Physico-Chemical Characteristics of Polyacrylamide Solutions after Mechanical Degradation through a Porous Medium
Authors: Noïk Ch. , Delaplace Ph. , Muller G.
Published: December 2007

Mechanical degradation of polymer solutions is an important problem which has to be assessed before injection into a reservoir. The main consequence is a viscosity loss due to macromolecules breakage which can strongly reduce the polymer solution effectiveness in controlling the water mobility inside the reservoir. Flow experiments have been performed by recirculating hydrolyzed polyacrylamide solutions through a small pack of sand particles. Polymer characteristics determined by viscometric and light scattering measurements have been analysed before and after injection at various flow rates. A normalized rate of degradation was defined by comparing the initial and final values of the intrinsic viscosity of solutions. The parameters investigated were: polymer concentration, molecular weight, concentration and nature of electrolytes.
Alcohol-Free Chemical Flooding: From Surfactant Screening to Coreflood Design
Authors: Sanz C. A. , Pope G. A.
Published: December 2007

Alcohol-free micellar solutions which yield high solubilization ratios (15-30 cc/cc), high final oil recoveries and eliminate the use of alcohol, a costly chemical, have been formulated for application in chemical floods.

A major difficulty was to preclude gels, liquid crystals, macroemulsions and precipitates along the composition path during a chemical flood. A screening strategy was applied to select among combinations of quite different surfactant structures. Corefloods were run with a blend of pure surfactants (C180CH2· CH2-S03Na, 8øC16SO3Na and 7øC14SO3Na), an ethoxylated sulfonate (6C16(OCH2·CH2)2 SC3 Na and a blend of an internal olefine sulfonate and a petroleum sulfonate. A slug size-efficiency curve obtained from corefloods with screened alcohol-free formulations, was compared to previous data with a conventional petroleum sulfonate/alcohol system (TRS 10-410/IBA) at 65° C taken as our basecase.

An equimolar blend of an internal olefin (C20-C24) sulfonate and a petroleum sulfonate gave a final oil recovery of 94% with a 13% Pvi slug size, 3v% surfactant concentration, at 80° C. When the slug size was reduced to 3% Pvi, the oil recovery still was 80%. Final results are compared to the basecase and other combinations tested and reported under comparable conditions.
High Temperature Synthetic Cement Retarder
Authors: Eoff L. S. , Buster Doug
Published: December 2007

A synthetic cement retarder which provides excellent retardation and compressive strength development has been synthesized. The response properties and temperature ranges of the synthetic retarder far exceed those of commonly used retarders such as lignosulfonates. The chemical nature of the new retarder is discussed and compared to another synthetic retarder.
Correlation Between Filter Cake Structure and Filtration Properties of Model Drilling Fluids
Authors: Li Yidan , Rosenberg Elisabeth , Argillier J. F. , Durrieu Josianne , Montes José
Published: December 2007

This study was undertaken in order to correlate the filtration behavior of water based muds with the structural properties of the cake. The structure of the cake is analysed by cryo scanning electron microscopy that enables the visualisation of a section of the frozen cake.

Static and dynamic filtration experiments were performed both through rock slices and paper filters. On rock slices it is possible to visualize the structure of the internal cakes that invade the pores of the rock and in particular to show a selective filtration of the polymer when using a formulation containing bentonite and a fluid loss reducer.

When compared to static filtration, dynamic filtration of a clay suspension gives higher filtrate volumes but leads to a cake texture characterized by a more regular network and smaller pore size. The augmentation of the filtrate volumes with shear rates is the result of both a decrease of the cake thickness and a diminution of connections between the clay sheets induced by shear rates. When polymer is added the structure of the pore walls seems less affected by shear rates, probably because of the high degree of dispersion already reached in the suspension by addition of the polymer and the ability of polymer to establish connections between particles.
An Approach for Simulation of Paraffin Deposition in Pipelines as a Function of Flow Characteristics With a Reference to Teesside Oil Pipeline
Authors: Hamouda A. A. , Davidsen S.
Published: December 2007

Paraffin deposition is experienced in pipelines during transportation of oil when the oil temperature is cooled below its paraffin deposition temperature. The formed paraffin crystals in the bulk flow is believed to be transported by molecular, brownian diffusion and shear dispersion(1,2,3). Gravity settling mechanism in previuos work in our laboratory has shown to contribute to the total paraffin deposition, however, to a lesser extent than the above mentioned mechanisms.

The work done here demonstrates that the paraffin deposition by molecular diffusion mechanism is a dominant one. This is in agreement with other previous studies done on the paraffin depoition(4,5). In this study, however, experimental designe was made to quantify this statement. The paraffin concentration gradient (dc/dr) is the driving force of the molecular diffusion mechanism (where r is the pipeline radius). In pipelines the cooling rate is one of many other factors that affect the paraffin deposition profile.

Equipment was designed to simulate the flow characteristics at pipeline pressure. A three dimentional model was developed for paraffin deposition rates at various flow regimes. The developed experimental approach and the designed equipment for simulating the pipeline conditions are presented in this paper.
Polarity Characterization of Crude Oils Predicts Treatment Trends in Field Development
Authors: Brüning I. M. R. de Andrade
Published: December 2007

A method for determinig crude oil polarity using inverse gas chromatography proved successful for classifying crudes as well as for assessing their ability to form stable emulsions with water.

Polarity determinations have been applied to the formation test crude oil samples collected in Albacora and Marlim deepwater fields of the Campos Basin, Rio de Janeiro, Brazil. The results have been compared with the polarities of the first produced crudes of the Basin and showed that the emulsion separation problems tend to increase.

Polarity results provided substantial data to help production field development decisions.
Molecular Modeling Gives Insight into Nonionic Surfactants
Authors: Gdanski Rick
Published: December 2007

This paper describes the study of a nonionic surfactant through the use of molecular modeling software. The surfactant was decyl alcohol capped with 8 moles of ethylene oxide. This nonionic surfactant is a strong water-wetting agent as well as a good aqueous foaming agent. Four molecular dynamics studies of a single surfactant molecule were conducted under the following conditions:

at a water surface at 80°F in bulk water at 260°F in bulk hexane at 80°F at a hexane/water interface at 80°F

The conformations of the surfactant were observed and compared to known solubility data. The results from molecular modeling dynamics calculations will provide new insights into the behavior of surfactant molecules at surfaces and interfaces. This methodology was also extended to aggregates of surfactants to promote understanding of wetting behavior and non-emulsification behavior. In this paper, two studies were performed involving aggregates: one in bulk water at 80°F and another in bulk water at 260°F.
Dynamic Phase Composition, Density, and Viscosity Measurements During CO2 Displacement of Reservoir Oil
Authors: Grigg Reid B.
Published: December 2007

A continuous phase equilibrium (CPE) apparatus was used to obtain composition, density, and viscosity for a West Texas recombined crude oil during the injection of high-pressure carbon dioxide (CO2). CO2 was continuously injected at constant pressure and flow rate. The system is maintained at constant pressure during CO2 injection by controlling the production rate. Compositions, densities, and viscosities of the produced fluids were determined at system pressures and temperature, providing continuous monitoring of fluid properties produced at outlets at both the top and bottom of the CPE apparatus.

The tests were run using both pure and impure CO2 at 105°F and pressures ranging from below to well above the minimum miscibility pressure (MMP). The solubility of the injected CO2 in the oil-rich phase was found to have little dependence on pressure, while the solubility of hydrocarbons in the CO2-rich phase increased with increasing pressure. Impurities in the injected CO2 did not significantly affect trends in composition, density, and viscosity of each phase. This work reports density, viscosity, component condensation and vaporization, and equilibrium constants for systems of CO2 and a West Texas crude oil at various reservoir conditions. Information from this work is required to tune models that simulate dynamic phase behavior in CO2 displacement tests, for both laboratory and field applications.

INTRODUCTION

The phase behavior of CO2/crude-oil systems has been investigated extensively since the 1960's.1–10 This interest was at its peak in the late 70's and early 80's, at the onset of many CO2 miscible flooding projects and higher oil prices. Interest continues as new projects come on stream and earlier projects mature.11 Studies to understanding the development,12–18 determination,19–23 and prediction24–30 of the MMP for both pure and impure CO2 injection have been ongoing for over thirty years. The objective of this work is to continue to examine how pressure and injection gas composition (pure and impure CO2) affect the dynamic phase behavior of CO2 injected into a recombined crude oil. This work complements earlier CO2 injection studies: one studying several different crude oils10 and another using a stock tank oil.4
A Amphoteric Copolymer Profile Modification Agent
Authors: HongGuan Wang , LianCheng Yu , HongKun Tian
Published: December 2007

This report provides a new gel profile modification agent prepared by a amphoteric copolymer (FT—213) and a nevol crosslinking agent (BY), and introduces the preparations of the amphoteric polymer, the crosslinking agent and the profile modification agent, the action mechanism, the conditions testing and the evaluations of the performances of the agent. The 45 well treatments in oilfields demonstrate that the agent can be prepared convienously, the agent has better compatibility and application performances, and the treatment life by using the agent is longer. 80000 tons increamental oil and 60000 m* decreasing water production have been achieved.
Fluid-Rock Interactions Between Xanthan-Chromium(lll) Gel Systems and Dolomite Core Material
Authors: McCool C. S. , Green D. W. , Willhite G. P.
Published: December 2007

Gelation of chromium(III)-xanthan systems in dolomite core material was investigated. Compositional changes in the gelant caused by interactions with the dolomite core material resulted in low permeability reductions for gelants prepared with chromium chloride, chromium acetate and a chromium diamine salt. The primary cause of incomplete gelation in the dolomite material was the increase in gelant pH that resulted in precipitation of chromium.