bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical Gas Saturation and Supersaturation in Low-Permeability Rocks
Authors: Kamath Jairam , Boyer R. E.
Published: December 2007

The laboratory methodology for determining critical gas saturation, Sgc, in field depletion processes is still uncertain. Through measurements on low-permeability rocks, we explore some of the key issues affecting laboratory determination of Sgc. Differences between laboratory depletion and external gasdrive experiments are measured and analyzed. We also investigate the relationship between average Sgc from material balance and true Sgc, source of supersaturation, gas nucleation conditions, and dynamics of gas bubble growth in depletion drive experiments. We assess the use of low-bubblepoint oils to reduce experiment time. Finally, we suggest some improvements to laboratory procedures.
The Instrumentation of the Conductor of a Subsea Well in the North Sea To Measure the Installed Conditions and Behavior Under Load
Authors: King G. W. , Soloman I. J.
Published: December 2007

The conductor design for subsea wells has not been studied to the same extent as the design of the subsequent casing strings. Models have been developed that incorporate riser and pile foundation analysis techniques to overcome this shortcoming. However, the models are dependent on a number of assumptions about the installed conditions, applied load, and resultant behavior, which have not all been fully validated. There have also been cases where the structural failure of the conductor has resulted in the loss of a well.

To enhance the understanding of conductor design, we initiated a project to install sufficient instrumentation on the conductor of a subsea well, and a data-acquisition system to enable the recording of the significant conductor parameters for comparison with model predictions. This paper describes the objectives of the measurement program, the design and testing of the instrumentation systems, the offshore installation and operation, the results obtained, and how the results have been interpreted.
Use of Volumetric-Average Shear Rate To Test Crosslinked Fluids With the Fann 50 Viscometer
Authors: Fan Yong , Holditch S. A.
Published: December 2007

We describe a method where laboratory tests of delayed, cross-linked fracturing fluids can be conducted, using different size bobs, to generate consistent, reproducible measurements of viscosity.
Volume Requirements for Aerated Mud Drilling
Authors: Guo Boyun , Rajtar J. M.
Published: December 2007

Aerated mud drilling has been recognized as having many advantages over conventional mud drilling, such as higher penetration rate, less formation damage, minimized lost circulation, and lower drilling cost. In some areas, the use of aerated mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. Maintaining an optimum combination of liquid and air flow rates is important in aerated drilling operations. However, most drilling operators are unclear on what constitutes the "optimum combination of the liquid and air flow rates." Guo et al. presented a mathematical approach to determining the flowing bottomhole pressure (BHP) for aerated mud drilling. This paper addresses the use of Guo et al.'s mathematical model to determine liquid and air volume requirements considering wellbore stability, pipe sticking, and formation damage as well as the cuttings-carrying capacity of the aerated mud. From a formation-damage-prevention point of view, the liquid fraction in the fluid stream should be as low as possible. However, a sufficient mud flow rate is always required to make the hole stable and to maintain the cuttings-carrying capacity of the aerated mud without injecting much air volume. This paper provides a simple approach to determining the liquid and air volume requirements for aerated mud drilling.
Development and Implementation of an HSE Management System in Exploration and Production Companies
Authors: Bentley P.D. , Mundhenk D.L. , Jones M.G. , de Jong Geert
Published: December 2007

This paper describes the experience to date with safety management systems (SMS's) and describes their implementation after the Piper Alpha disaster and Lord Cullen's report. It also shows the gradual expansion of these systems toward fully integrated health, safety, and environment (HSE) management systems. Our company policy, which was clearly stated before publication of Lord Cullen's report, is that work should not start until the appropriate controls are in place. Work based on this policy and on objective-setting SMS's within Shell IntI. Petroleum Mij. (SIPM) E&P coordination started in earnest soon after the publication of the report in Nov. 1990 and has continued without interruption since that time. Objective-setting systems may be defined as systems where the company management sets its own objectives or goals on the basis of functional rather than prescriptive requirements and then goes on to demonstrate how such goals have been, or are being, met. The paper ends with a projection of what may be expected in the future.

Introduction

Following the Piper Alpha disaster and the in-depth public inquiry led by Lord Cullen, the recommendation was made that all offshore installations on the U.K. continental shelf should have safety cases similar to those already required under the U.K. Control of Industrial Major Accident Hazards Regulations. This recommendation was given effect by means of the safety-case regulation within the U.K. with a Nov. 1993 deadline for the submission of safety cases. Shell Expro, as a major operator in the U.K. sector of the North Sea, had already begun work on its safety cases before publication of the Cullen report and was one of the companies that contributed to the so called "voluntary" safety cases before this date.

It was apparent to E&P management within SIPM that the SMS and the safety case provided better assurance of safe operation and were of real value to Shell operations worldwide. (In this paper, Shell is sometimes used for E&P companies of the Royal Dutch/ Shell group in general, and Shell E&P is used if experience was gained through technical service agreements supported by SIPM E&P). It was also clear that a worldwide move toward such systems would take place. Thus, application of these systems was both good business and appropriate for all Shell E&P operating companies. As a direct consequence, an integrated project team (both project engineering and operations) was set up to implement SMS and safety cases throughout Shell upstream operations worldwide.
The Differentiation Method in Rheology: II. Characteristic Derivatives of Ideal Models in Poiseuille Flow
Authors: Savins J.G. , Wallick G.C. , Foster W.R.
Published: December 2007

Inasmuch as the differentiation and integration methods represent different modes of rheological analyses, a dual scheme of analysis using both methods should lead to a generalized method of data analysis. A dual differentiation. integration method of analysis is applied here to the Poiseuille flow of a variety of ideal Generalized Newtonian and viscoplastic models. Using machine processing techniques, the result is a spectrum of response patterns which are expressed in terms of certain derivative functions. It is shown that these characteristic functions form the basis of a highly-sensitive analytic technique for optimizing the selection of the most appropriate functional relationship between shear rate and shearing stress.

Introduction

In the first paper of this series, Savins, Wallick and Foster presented an historical review of the salient features of the differentiation method of rheological analysis in Poiseuille flow, and also indicated how the method could be applied to problems involving plane Poiseuille flow. It was shown that the differentiation and integration methods, although basically not incompatible, do represent different modes of rheological analysis. This suggests that valuable background information regarding the probable response characteristics of real data obtained with the differentiation method can be obtained from an integration method-differentiation method analysis of the response of a variety of ideal rheological models. The present paper describes how this dual method of analysis has been applied to suites of idealized models representing a wide variety of Generalized Newtonian and viscoplastic behavior which have received attention at various places in the literature.

THEORETICAL CONSIDERATIONS

NEWTONIAN LIQUID

For a liquid of constant viscosity

.............................(1)

By substituting Eq. 1 in Eq. 9 of Ref. 1 and integrating, it is easily shown that for Poiseuille flow

.......................(2)

and, hence,

....................(3)

...........................(4)

GENERALIZED NEWTONIAN SYSTEMS

Odd Power

This model is of the form

......................(5a)

Note that it represents a Maclaurin-type series expansion, based on the Newtonian model, which is restricted to the odd powers of the stress.

SPEJ

P. 309^
Method for Calculating Forces Produced by Irregular Waves
Authors: Wheeler J.D.
Published: December 2007

This new method for calculating wave forces on offshore structures is based on an extension of Airy theory for two-dimensional waves and uses a linear filtering technique to calculate wave forces as a function of time for wave profiles of arbitrary shape and length.

Introduction

Interest in wave-force predictions has been increasing in recent years with the increasing worldwide investment in offshore operations and the movement into deeper water. The larger structures required in deeper water increase the need for rapid and accurate waveforce predictions. This paper presents a method for computing wave forces from an ocean-wave profile by a linear filtering technique and compares these computed forces with measurements. The linear filter employed is developed from a modification of small-amplitude wave theory suggested by wave-tank studies and used to calculate water velocities and accelerations. In the linear filtering method, a wave train of any length and any degree of irregularity can be used in design and dynamic studies of offshore structures. Further, the change of the wave profile shape with time (dispersion) can be allowed for. Velocities and accelerations calculated with the linear filter and introduced into an equation proposed by Morison et al. permits calculation of wave forces. Force coefficients required in Morison's equation were determined by fitting calculated forces to observed hurricane wave-force measurements. Consequently, the force coefficients should be used only with the calculation procedures presented in this paper; further, their application has been limited to calculation of forces on members similar in size and surface properties to the test member used to obtain the measured properties to the test member used to obtain the measured forces.

The force predictions are compared with force measurements made in about 400 waves at various heights along a 44-in.-diameter piling in 99 ft of water during Hurricane Carla in 1961. The procedure gives acceptable prediction of maximum forces at all heights above bottom. Force profiles in the four largest measured waves are reproduced with reasonable fidelity, and the peak forces in these largest waves are closely reproduced. Additional force measurements made in shallow water (34 ft) are not referred to in this paper. The wave theory used is less applicable in shallow water, leading to considerable scatter in fitting results. The force measurements indicate that wave forces fall off sharply near the surface of the water. Reproduction of the actual flow regime near the wave surface requires further modification of any way theory. This additional modification is not discussed here.

Procedure Used to Predict Wave Forces Procedure Used to Predict Wave Forces Force Equation

The horizontal force per foot of vertical piling length is calculated as a function of time t and height z above the ocean bottom as:

(1)

Eq. 1, proposed by Morison et al., represents the total force as a sum of drag and inertial forces.

JPT

P. 359
Wave Forces: Data Analysis and Engineering Calculation Method
Authors: Dean R.G. , Aagaard P.M.
Published: December 2007

This method for calculating the force of ocean waves on offshore drilling structures utilizes a mathematical model for the flow field of highly nonlinear waves; the method is considered applicable to a broad range of wave conditions commonly encountered in offshore design.

Introduction

An extensive body of knowledge is developing in the area of ocean wave forces on cylinders. Excellent summaries appear in Refs. 1 and 2; important contributions of mathematical models used in wave-force calculations are described in Refs. 3 through 5; and wave-force measurement installations are described in Refs. 6 and 7. From theoretical and experimental work has come a variety of wave-force calculation methods for use in engineering; one such example is presented in Ref. 8. Most published methods are presented in Ref. 8. Most published methods are based on the analysis of relatively few waves of low to moderate height and mathematical models that involve major simplifications in the representation of real ocean waves. There has been a need, therefore, to improve the mathematical model and to use information from larger waves. A mathematical model was developed and proved to be a substantial improvement over the available models. Using this model and data from large-amplitude waves measured in the Gulf of Mexico, Standard Oil Co. of California developed the method reported here for use in design of offshore structures.

Selection of a Mathematical Model

The mathematical model used in the wave-force calculation method was picked to be compatible with specification of design wave conditions in terms of a single wave; the calculated forces are used in a space-frame loading program to calculate the loads on a complete structure. Although this deterministic, single-wave approach appears to conflict with the fact that the sea is non-deterministic and can be described only statistically, for the following reasons the deterministic approach was chosen.

Natural periods of structures considered when the method was developed were much shorter than the period range of significant wave energy; hence, wave loads could be treated as static loads. Nonlinear wave theories could be used for calculating the single wave, whereas time series representations used in the statistical models were not developed to the point that nonlinear wave characteristics could be modeled. Statistical characteristics of a sea that are of importance to the static load case could be approximated in selection of design wave heights and calculation of wave forces.

Considerable progress is being made on calculation methods using time-series description of waves and forces, and such methods will be used when longer period structures, requiring dynamic analysis, are studied.

JPT

P. 368
Implementing Environmental Management System on Oilfield Operation in Sumatra: Field Operation Case Study
Authors: Kosasih Achmad , Shobirin Mohammad
Published: December 2007

Given the progressively increasing level of government and public environmental awareness, environmental management has emerged as a key component in the overall management of hydrocarbon exploration, development, and production. This paper examines how Lasmo Oil (Malacca Strait) Ltd. (LOMSL) has set up and implemented its environmental management system to comply with Indonesian regulatory requirements and to understand and deal with environmental and community issues proactively in its areas of operation. Initiated in 1989, the current achievements of the LOMSL are described. The results show that by setting up an environmental management system and positively implementing a comprehensive environmental management program, LOMSL has managed to solve its major environmental problems. We found that to establish and to maintain a satisfactory level of environmental performance, broad-ranging consideration must be given to aspects of a regulatory and institutional, socioeconomic, and ecological nature. Management commitment and participation is also identified as essential if a sustained level of high-quality environmental management is to be achieved.

Introduction

LOMSL's history of operation in Malacca Strait started in early 1980. Seismic and exploration drilling were initiated, and in 1984, under the name of HOMSL, the first oil field, the Lalang field, started to produce oil.

Currently, LOMSL operations consist of six fields: the offshore Lalang field (production began in June 1984 from 15 wells), the offshore Mengkapan field (production began in Dec. 1986 from 10 wells), the onshore Melibur field (production began in Dec. 1986 from 32 wells), the onshore Kurau field (production began in Jan. 1988 from 29 wells), the onshore Padang Selatan field (production began in Dec. 1990 from 11 wells), and the onshore MSBV field (production began in Aug. 1993 from 1 well).

Since LOMSL started operation in the Malacca Strait, management has made a strong commitment to managing the environment properly. One person was dedicated to health, safety, and environmental matters. An environmental impact assessment for Lalang field was developed before operation of the field in 1984, even though there was no government regulation effective at that time that required an environmental impact assessment study for a project development.
Application of Probability to the Design of Single-Point Moorings
Authors: Haring R.E. , Adams R.B. , Beazley R.A. , Kipp K.L.
Published: December 2007

HARING, R.E., MEMBER AIME, ESSO PRODUCTION RESEARCH CO., HOUSTON, TEX. ADAMS, R.B., ESSO STANDARD OIL (AUSTRALIA) LTD., SYDNEY, AUSTRALIA BEAZLEY, R.A., ESSO RESEARCH and ENGINEERING CO., LINDEN, N.J. KIPP, K.L., ESSO PRODUCTION RESEARCH CO., HOUSTON, TEX.

A procedure has been developed to analyze mooring forces and to aid the selection of design parameters for single-point mooring systems. The parameters for single-point mooring systems. The results of a study indicate that a conventional SPM buoy could be used successfully to permanently moor a 52,000-dwt tanker in 260 ft of water under moderate sea conditions. The procedure utilizes scaled-model data and environmental observations to derive force-probability functions, which define The probability of exceeding any given force in the mooring system.

Introduction

There has been a steady increase in the application of monomoorings in loading terminals for exporting crude oil from shore storage and in discharging terminals for handling products and importing crude to refineries. Almost all the monomoorings have been single-point mooring buoys. Their general characteristics are illustrated in Fig. 1. The buoy itself is circular and of all-welded construction. It is subdivided into watertight compartments with provisions to handle the anchor chains, rotating manifold, and bow mooring hawser attachment. About 60 systems of this type have been installed or are under construction in the free world. Their main application has been in water depths less than 150 ft and in relatively calm, sheltered areas. Increased use of super tankers has stimulated further interest in loading buoys for deeper water.

In at least two instances single-point mooring buoys have been used for floating, crude-oil storage vessels. As offshore oil fields are discovered in areas far from existing crude-oil markets or gathering systems, the use of single-point mooring systems for floating storage vessels will increase. The most important considerations in the design of single-point mooring systems for this application will be the continuous exposure to environmental forces, the more severe conditions typical of the open ocean, and water depths greater than are found at existing installations. A design procedure should allow the engineer to identify the probability of exceeding specified forces induced in the mooring system by the ocean environment. Mooring systems are usually designed well within the nominal strengths of their components to allow for fatigue, corrosion and short-duration high stresses. Therefore, even if the induced forces exceed the design forces, failure will not necessarily result. Rather, this condition alerts the marine operator to the need for corrective action or suspension of operations to prevent continued exposure of the system to excessive forces.

SPEJ

P. 219
Viscous Fluids Characterize the Crushed Zone
Authors: Rochon Jean , Creusot M. R. , Feugas Daniel , Thibeau Sylvain , Bergerot J-L.
Published: December 2007

The crashed zone surrounding a perforation tunnel, which contributes to the overall skin effect, is well documented. Many authors have proposed equations to predict the pressure drop caused by both laminar and high-velocity flow through the crushed zone. However, determining the thickness of the crushed zone and its permeability always has been a major problem.

We obtained cylindrical single-shot core samples perforated under API conditions. We evaluated the damage surrounding the perforation tunnels in the laboratory using a new technique. The core is saturated with a low-viscosity refined oil. The low-viscosity oil is flushed at a constant flow rate by another refined oil, which has a much higher viscosity. The differential pressure is monitored as the miscible front moves radially outwards. The rate of change of the differential pressure is affected as the high-viscosity oil invades zones with different permeabilities.

Our interpretation of the pressure differential was done analytically. We obtained results in terms of effective crushed-zone thickness and crushed-zone permeability alteration. Such results can be used to calculate the contribution of the crushed zone to the skin effect.

The success of this nondestructive laboratory technique leads us to evaluate the possibility of injecting a viscous fluid into a real well to investigate in-situ formation damage.
Simple Method Predicts Downhole Shaped-Charge Gun Performance
Authors: Ott R. E. , Bell W. T. , Harrigan J. W. , Golian T. G.
Published: December 2007

A simple method is proposed for predicting downhole shaped-charge gun performance based on the use of API RP 43, Edition 5, Sec. 1 data. API Sec. 1 has been the preferred method for assessing perforating gun system performance because of the simplicity of the test and its use of standard field guns fired at maximum shot densities and positioned as they would be in an actual well. The validity of the proposed method is demonstrated, allaying past concerns regarding the translation of data from Sec. 1 nonrock, nonstressed concrete targets to downhole conditions. The new method is based on an observed linear relationship between Edition 5, Sec. 1 and Sec. 2 penetration information. The applicability of the well-known Thompson relationship between formation compressive strength and perforator penetration to Edition 5, Sec. 2 and therefore to Sec. 1 data is shown. Incorporating necessary corrections for casing entrance hole size, downhole effective formation stress, and casing configurations different from those in the API test completes the translation of surface data to downhole conditions.
Pore Pressure Estimation From Velocity Data: Accounting for Overpressure Mechanisms Besides Undercompaction
Authors: Bowers Glenn L.
Published: December 2007

A new method for estimating pore pressure from formation sonic velocity data is presented. Unlike previous techniques, this method accounts for excess pressure generated by both undercompaction, and fluid expansion mechanisms such as aquathermal pressuring, hydrocarbon maturation, clay diagenesis, and charging from other zones.

The method is an effective stress approach; the effective stress is computed from the velocity, and the result is subtracted from the overburden stress to obtain pore pressure. To include multiple sources of overpressure, a pair of velocity-vs.-effective-stress relations are introduced. One relation accounts for normal pressure and overpressure caused by undercompaction. The second is applied inside velocity reversal zones caused by fluid expansion mechanisms.

Example applications of the method are presented from the U.S. gulf coast, the Gulf of Mexico, and the Central North Sea. Some other pore pressure estimation approaches are also examined to demonstrate how these techniques have unknowingly accounted for overpressure mechanisms other than undercompaction.

It is also explained how velocity-vs.-effective-stress data can be used to identify the general cause of overpressure in an area. For instance, the empirical correlation of Hottman and Johnson indicates that overpressure along the U.S. gulf coast cannot be due only to undercompaction.
Environmentally Acceptable Water-Based Mud Can Prevent Shale Hydration and Maintain Borehole Stability
Authors: Simpson J. P. , Walker T. O. , Jiang G. Z.
Published: December 2007

This paper presents laboratory and field results showing that an environmentally acceptable water-based mud (WBM) can be formulated to act like an oil-based mud (OBM) in preventing hydration, pore-pressure increase, and weakening of shale by effectively developing sufficient osmotic force to offset the hydraulic forces acting to cause water flux into the shale. We also show that this methyl glucoside system has other performance characteristics similar to OBM's, such as lubricity, filtration control, and tolerance for common WBM contaminants, thus meeting the needs for drilling high-angle or even extended-reach wells.
Visualization of Reservoir Simulation Data With an Immersive Virtual Reality System
Authors: Williams B. K.
Published: December 2007

This paper discusses an investigation into the use of an immersive virtual reality (VR) system to visualize reservoir simulation output data. The hardware and software configurations of the test-immersive VR system are described and compared to a nonimmersive VR system and to an existing workstation screen-based visualization system. The structure of 3D reservoir simulation data and the actions to be performed on the data within the VR system are discussed. The subjective results of the investigation are then presented, followed by a discussion of possible future work.
Identification of Well-Test Models by Use of Higher-Order Neural Networks
Authors: Kumoluyi A. O. , Daltaban T. S. , Archer J. S.
Published: December 2007

In a well test, the central objective is to "prove" the formation in terms of a sustainable economic flow rate. This objective is related to the characterization of the reservoir and the estimation of its parameters, tike permeability and skin, by knowledge of only the input and output signals, such as pressure and flow rate, and, in certain cases, other reservoir characteristics, such as the drainage area and the distance to faults.

Interpretation efforts, therefore, can be performed in two phases: (1) the identification of "reasonable" theoretical reservoir models representing the field data, and (2) the estimation of pertinent parameters of the selected theoretical reservoir model. The second phase is well established in the literature, whereas many problems are associated with model selection, such as uncertain data, incomplete data, and the ambiguity of the models (i.e., more than one model might be representing the field data).

One can identify the theoretical models based on similarities of the curvature of both the type curves (from both simple analytical models and complex numerical models) and the field data. The whole process can be conceived as a pattern-recognition task. In this paper, we present an approach by which it is possible to identify an appropriate welltest model in a consistent and objective manner, thereby reducing some of the problems associated with the task. The approach is based on the application of higher-order neural networks (HONN's).

Conventional neural networks are used in general for both optimization and classification tasks. For classification purposes, these networks will find appropriate mappings to any set of patterns with dependence on both spatial and temporal positions. That is, such networks find it extremely difficult and often impossible to deal with patterns invariant to some transformation groups, such as scaling, translation, and rotation. Well-test models are inherently translation invariant with respect to the field data and are also scale invariant. Thus, we propose the use of HONN's, by which we can encode the invariant properties of patterns into the architecture of the network, thereby constraining some of its weights (parameters). Constructing such networks enables us to identify well-test models in an automated and robust manner. Moreover, these networks are both pattern and training-rule independent. Additionally, the training time for such networks is extremely fast compared to conventional neural networks.

Our system has been used to identify various models, such as naturally fractured reservoir, homogeneous reservoir, multilayer reservoir, dual porosity, commingled, and fractured wells. We performed all implementation using VISUAL C++ 1.0 and Microsoft Foundation Classes 2.
Migrating Legacy Petroleum-Engineering Applications to Open-Systems Environments
Authors: Little Todd , Chien David , Corbell Rory , Rahi Ahsan M. , Sinclair Craig
Published: December 2007

We present a case study involving the software life cycle of a suite of commercial petroleum-engineering reservoir-simulation legacy applications. As with typical petroleum legacy applications, these are designed for DOS or VMS environments, written in FORTRAN, based on the Graphics Kernel System (GKS) for graphics, and have hierarchical menu trees.

We replaced the hierarchical user interface with a C++ toolkit to provide a Motif look and feel, while keeping the remainder of the application in FORTRAN. As a result, the application developers well versed in FORTRAN can continue to augment the engineering portion of the application, allowing training in C, C++, X, and Motif to be spread out over time.

This migration path has had several major benefits over a complete rewrite of the software. We have been able to produce an open-systems application significantly faster than what would be required for a software rewrite. Additionally, this path has preserved compatibility with the legacy application and, therefore, provided enhanced reliability.
Integrating Knowledge-Based Techniques Into Well-Test Interpretation
Authors: Harrison I. W. , Fraser J. L.
Published: December 2007

The goal of the Spirit Project was to develop a prototype of nextgeneration well-test-interpretation (WTI) software that would include knowledge-based decision support for the WTI model selection task. This paper describes how Spirit makes use of several different types of information (pressure, seismic, petrophysical, geological, and engineering) to support the user in identifying the most appropriate WTI model. Spirit's knowledge-based approach to type-curve matching is to generate several different feasible interpretations by making assumptions about the possible presence of both wellbore storage and late-time boundary effects. Spirit fuses information from type-curve matching and other data sources by use of a knowledge-based decision model developed in collaboration with a WTI expert. The sponsors of the work have judged the resulting prototype system a success.
Tools, Processes, and Systems: An Integrated Approach to Petroleum Software Training
Authors: Ames L. C. , Reese R. D.
Published: December 2007

The petroleum industry has fewer analysts, engineers, and technicians than it did a decade ago. To handle this increased workload, the remaining individuals use a variety of computing options. The question under consideration here is how to most effectively train the right people to use the appropriate computing tools to solve corresponding problems.

As we have planned our software training at Oil and Gas Consultants Intl. Inc. (OGCI), we have found it useful to divide computing skills into three levels—tools, processes, and systems. These levels are progressively more complex; they build on each other, and represent increasingly higher levels of analysis. This paper draws from our experience training nearly 800 people around the world, in 1993 alone, to better use petroleum software. We use the multi-level approach to highlight training challenges and to suggest possible improvements.
Quality User Support Supporting Quality Users
Authors: Woolley T. C.
Published: December 2007

This paper describes how Oryx Energy Co. addressed problems and opportunities created by the explosive growth in computing power and needs coupled with industry contraction. A successful user-support strategy is described. Characteristics of the program include (1) client-driven support, (2) empowerment of highly skilled professionals to fill the support role, (3) routine and ongoing modification of the support plan, (4) use of the support assignment to create highly trained advocates on the line, and (5) integration of the support role to the reservoir management team. Results of the plan include a highly trained work force, stakeholder teams that include support personnel, and global support from a centralized support organization.
Modeling Decisions in Emergency Situations
Authors: Doheny J. G. , Fraser J. L.
Published: December 2007

In this paper, we describe a methodology and supporting software tool that we developed for helping to model the decisions that people make in emergency situations offshore. We believe that this is the first time that people's decision-making has been incorporated into egress and evacuation models. Our work, therefore, is an important first step in the introduction of improved approaches to the evaluation of platform layout, facilities, and emergency procedures.

We worked with our collaborators to integrate our model of people's decisions with their model of people's movement. Our result indicates that people's movements are modified by factors such as their reactions to alarms, their reactions to hazards, their familiarity with the installation, their training, and their roles. Our program has a generic architecture for modeling decisions. We used "scripts" to define typical actions or procedures associated with particular conditions: people in the computer simulation adopt particular scripts according to the situations in which they find themselves.

In future developments, we would like to improve the decision model by incorporating communication between individuals as a scenario proceeds. This would be particularly useful in (1) scenarios that go beyond muster to evacuation, (2) scenarios where there is significant structural damage, (3) scenarios where there are casualties, and (4) scenarios that cannot be simulated realistically in exercises.

The software runs on a 486 PC under Windows 3.1. Safety analysts can build floor plans and set up scenarios with different facilities, populations, or hazards to determine their various effects.
Multivariate Optimization of Networked Production Systems
Authors: Fujii Hikari , Horne Roland
Published: December 2007

Today, many oil and gas production systems have flowline networks with many wells and surface pipelines. In the design of such production systems, the determination of parameters like separator pressure, the diameters of tubing, pipeline, or surface choke, and the length of pipeline is important to the achievement of an optimum production rate.

The optimization of such problems, however, has been difficult because of the nonlinearity of the solution caused by the interaction between these parameters. In this work, multiple production parameters were optimized simultaneously in well networks in terms of a profit-based objective function, such as total production rate, net income from the oil product, or present value discounted by interest rates. The techniques applied in this work were Newton-type methods (derivative based), the polytope method (function-value based), and a new technique that uses a genetic algorithm (GA). On the basis of several test calculations on various types of optimization problems, the polytope method turned out to be the most efficient and consistent for low dimension problems with small numbers of wells, while the GA performed well in large systems with many variables to be optimized.

The optimization of a pipeline network system was achieved successfully without any limitation on the selection of objective functions and decision variables to be optimized. The optimization technique can be used in the design stage of newly developed fields or in the planning of workovers in existing fields. The combination of this technique with reservoir simulation would be a powerful tool in a project implementation design process.
Laboratory Investigation of Combination of Alkali/Surfactant/Polymer Technology for Daqing EOR
Authors: Shutang Gao , Huabin Li , Hongfu Li
Published: December 2007

Alkali/surfactant/polymer (ASP) formulas were developed for the Daqing oil field, Peoples Republic of China, with two surfactants from the U.S. (Petrostep B-100 and a blend of TRS-18 and TRS-40) and one Chinese surfactant (PS-D2). Each ASP solution gave interfacial tension (IFT) values in the range of 1 × 10−3 mN/m. Rheologic studies with polyacrylamide polymers indicate that solution viscosity decreases with alkali addition, as does the pseudoplasticity of the solution. Addition of surfactant to the alkali/polymer solution increases the solution viscosity with no slope change in the viscosity-vs.-shear-rate plot. Incremental oil recovery was higher than that with waterflood; 20% original oil in place (OOIP) for 0.2-PV ASP injection and 33% OOIP for 0.3-PV ASP injection in Daqing core. Surfactant and alkali retention were both < 1 mg/g sand. The positive results of this laboratory study provided a fluid formula for a pilot ASP flood in the Daqing oil field.
The Release of Solution Gas from Waterflood Residual Oil
Authors: Hawes Robert I. , Dawe Richard A. , Evans Richard N.
Published: December 2007

A series of experiments have been undertaken to visually observe the formation and growth of bubbles formed when solution gas is released from waterflood residual oil. The experiments were performed using an etched glass micromodel which represented a two-dimensional section of a sandstone core. This micromodel was mounted vertically within a temperature controlled water bath, and the flow of fluids within the micromodel was observed through a microscope and recorded on video. Experiments were performed under water-wet conditions, using a mixture of low boiling point hydrocarbons, which had a positive spreading coefficient for the oil phase in contact with water and its own vapour. In these experiments the gaseous phase was produced by raising the temperature of the micromodel until it reached the bubble point of the oil, at atmospheric pressure.

The following features were observed:

In keeping with the spreading oil, all gas that was generated as bubbles within the oil ganglia from which it was produced. Bubbles did not form in all ganglia, nor did they all form at the same time. As more gas was released from solution, the bubbles expanded, pushing the gas/oil and oil/water interfaces outwards. Buoyancy forces had little initial influence on the expansion, which occurred in all directions. The bubbles themselves were unable to migrate, and the gas remained immobile until the volume of individual bubbles had increased to the extent that adjacent bubbles became connected. The oil phase was transformed from being immobile droplets or ganglia, into films surrounding the gas bubbles, in which the oil was mobile.

A mathematical model for the growth of a single bubble has been developed, which includes the effect of gravity as well as capillary forces in controlling the development of the bubble. Calculations using this model show that the initial growth pattern is dominated by capillary forces, but as the bubble becomes larger buoyancy forces start to play an important part in the way that the bubbles grows.
CO2 Foam: Results From Four Developmental Field Trials
Authors: Hoefner M. L. , Evans E. M.
Published: December 2007

Four pattern-scale CO2-foam field trials were conducted to determine the effectiveness of foam in reducing CO2 channeling, to evaluate the economic potential of the process, and to develop application criteria and procedures. The trials were conducted under various process and geologic conditions so that the resulting technology would be applicable in a number of different CO2 floods. Two different surfactants, Rhodapex (formerly Alipal) CD-128 and Chaser CD-1045, and two injection methods, alternating vs. coinjection of CO2 and surfactant, were tested in San Andres (west Texas) and platform carbonate (southeast Utah) reservoirs. In all, 161,000 Ibm of active surfactant was injected in the four field trials, with one well undergoing foam treatment for as long as 18 months. The treatments resulted in a significant reduction in gas production and indications of increased oil production. The total cost of the four treatments (excluding labor and overhead) was $700,000.
Case History and Appraisal of the Medicine Pole Hills Unit Air-Injection Project
Authors: Kumar V. K. , Fassihi M. R. , Yannimaras D. V.
Published: December 2007

The Medicine Pole Hills Unit (MPHU) EOR project is the deepest air-injection/in-situ-combustion project in the Williston basin. A unit comprising 9,600 acres with 13 producing wells was formed in July 1985, and air-injection operations began in Oct. 1987. Laboratory combustion tests and detailed feasibility studies were completed before starting the full scale project. The combination of light oil (39°API), carbonate formation, hot reservoir (230°F), and low permeability (1 to 30 md) makes this a unique air-injection project. Cumulative air injection as of Dec. 1993 was 12 Bscf. This paper reviews production performance of the MPHU to date. Oil production from the unit has shown a significant increase over its historical decline, and a processing plant has been installed to recover the liquids stripped from the oil by the produced flue gas. Although well workovers, acid fracturing, and pump changes in some producers complicate the determination of the oil response to air injection, production decline-curve analysis was used to estimate the incremental oil recovery due to air injection. The current air/oil ratio (AOR) is 8 Mscf/STB. Also discussed are the changes in air utilization over time, the benefits of the liquids recovery from the produced-gas stream in such a light-oil project, and an estimate of the field burned volume.
Simulating Flow in Heterogeneous Systems Using Streamtubes and Streamlines
Authors: Thiele M. R. , Batycky R. P. , Blunt M. J. , Orr F. M.
Published: December 2007

We present a fast technique for modeling convective displacements that are dominated by large-scale reservoir heterogeneities. The novel feature of our method is the integration of any 1D solution with periodically updated streamtubes or streamlines to simulate displacements in two and three dimensions. We use streamtubes in two dimensions and streamlines in three dimensions. We construct approximate solutions using two to five orders of magnitude less computation time than by conventional simulation. Our approach allows us to decouple the physics describing the displacement from the size of the grid used to model the reservoir geology. In addition, because 1D solutions are often analytical, or can be obtained numerically using higher-order methods, the resulting 2D and 3D solutions are free of numerical diffusion.

We present examples in two and three dimensions for a variety of displacement mechanisms and compare our results with conventional finite-difference solutions showing excellent agreement. Because of its speed, our method becomes particularly effective for estimating the uncertainty in forecasting reservoir performance resulting from the uncertainty in the description of the reservoir geology.
Modeling Early-Time Gas Migration Through Cement Slurries
Authors: Prohaska Michael , Fruhwirth Rudolf , Economides M. J.
Published: December 2007

This work identifies a mechanism that could be responsible for substantial gas invasion into a cemented column after placement. A model is developed to predict the risk for gas invasion and to aid in the design of a cement job suggesting a "tail" and a delayed "lead" slurry. The model provides the absolute theoretical migration height when cement properties and formation parameters are known. The work accounts for the calculation of the hydrostatic pressure drop, for the estimation of the inflow rates resulting from shrinkage and filtration, and for the description of the bubble-rise process. A sensitivity study on important design and well parameters is included.
Air Foam Improves Efficiency of Completion and Workover Operations in Low-Pressure Gas Wells
Authors: Scott S. L. , Wu Yulin , Bridges T. J.
Published: December 2007

Air foam has developed into a cost-effective alternative to nitrogen foam for completion and workover operations in low-pressure gas wells. In most cases, air foam represents less than one-third the cost of nitrogen and is being used with increasing frequency in the Texas/ Oklahoma Panhandle region of the U.S. This paper addresses the three traditional concerns associated with the use of air foam: (1) lower available pressures and rates, (2) flammability, and (3) corrosion. The paper also details the use of these portable air-foam units in circulating operations, including coiled tubing. Newer applications are discussed where air foam can reduce costs compared with swabbing. Experimental results demonstrate that air foam can be used at circulating temperatures up to 120°F with commercially available corrosion inhibitors. We show that extension of air foam to deep wells with temperatures up to 350°F is possible with a newly developed inhibitor.
An Integrated Approach to Gas Well Deliverability Analysis, Hugoton Field
Authors: Sweeney M. J. , Sites O. A.
Published: December 2007

This paper describes an integrated approach for analyzing gas well deliverability for a large complex well system by using electronic gas measurement (EGM) data, inflow/outflow performance (IOP) prediction, material balance, and pipeline modeling. The primary benefit is a more accurate production forecast for project analysis.

In the past, determining gas well deliverability for a large multiwell system (MWS) was difficult because an efficient method was not available to analyze fully rate and pressure information, completion configuration, proration regulations, state test information, gathering system response, and reservoir material balance.

Recent developments in technical software and hardware and the widespread use of EGM have led to more efficient and accurate determinations of wellhead deliverability.