bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unstable Two-Fluid Flow in a Porous Medium
Authors: Varnon J.E. , Greenkorn R.A. 
Published: December 2007

Abstract
This paper reports an investigation of unstable fingering in two-fluid flow in a porous medium to determine if lambda the dimensionless finger width, is unique For a viscous finger A is the ratio of finger width to the distance between the tips of the two trailing fingers adjacent to the leading finger. For a gravity finger lambda is defined as the ratio of finger width, to "height" of the medium perpendicular to hulk flow. This work confirms previous experiments and existing theory that for viscous fingering lambda approaches a value of 0.5 with increasing ratio of viscous to interfacial force. However, for a given fluid pair and given, medium, this ratio can he increased only by increasing the, velocity. Experiments on gas liquid systems show that the asymptotic value of lambda with velocity is not always 0.5. Apparently, for gas-liquid systems, the influence of the interfacial force cannot always he eliminated by increasing the velocity. For such systems lambda is a function of fluid pair and media permeability. If the gravity force normal to the hulk permeability. If the gravity force normal to the hulk flow is active, it damps out the viscous fingers except for an underlying or overlying finger. The dimensionless width of this gravity finger strongly depends on velocity and height of the medium, as well as the fluid and media properties. The existing experiments and theories are reviewed and the gravity, stable, and viscous flow regimes are described in view of these experiments and theories. The existence of a gravity-dominated unstable regime, a gravity-viscous balanced stable regime, and a viscous-anminated regime was demonstrated experimentally by increasing flow velocity bin a rectangular glass head model. Asymptotic values of the dimensionless finger width were determined in various-sized Hele-Shaw models with gravity perpendicular and parallel to flow. The dimensionless perpendicular and parallel to flow. The dimensionless finger width lambda was determined as a function of applied force, flow resistance, and fluid properties. The results are interpreted dimensionally. Some comments are made concerning possible scaling and meaningful extensions of theory to describe these regimes in three-dimensional flow. Previous description of unstable two-fluid flow in porous media is mainly restricted to studies of viscous-dominated instability. The direction of this study is to provide data and understanding to consider the more realistic problem of predicting flow in three dimensions that may result in instabilities that are combinations of all, four flow regimes.
Influence of Rock Heterogeneities on Fracture Geometry in the Green River Basin
Authors: Mukherjee Hemanta , Morales R. H. , Denoo S. A. 
Published: December 2007

SummaryConstant-height models, in the absence of significant barrier stresses, frequently overpredict fracture half-lengths. This has been a problem in the fracture design of the Frontier and Dakota formations in the Greater Green River basin. Both formations often experience unlimited fracture-height growth as a result of a lack of barrier-stress contrast. This paper presents some of the implications of uncontained fracture-height growth in these formations on fracture design through 2D and 3D fracture geometry modeling. The effects of the minimum in-situ-stress profile, Young's modulus profile, and fluid-loss contrast on the fracture geometry evolution are studied. Actual field example data from a Frontier well are used for the sensitivity analyses.
Preventing Lost Circulation in Severely Depleted Unconsolidated Sandstone Reservoirs
Authors: Ali Aziz , Kalloo C. L. , Singh U. B. 
Published: December 2007

Summary
This paper discusses the field application of a blend of lost-circulation materials (LCM's), in a water-based drilling fluid to drill through multiple severely depleted, unconsolidated sandstone reservoirs. Simple laboratory tests are documented to show the sealing effectiveness of the LCM blend. Major benefits of the LCM blend include lost-circulation prevention, elimination of intermediate-drilling-casing strings, and substantially lower well costs.
Experiences in Automating in Pipe-Handling Functions
Authors: Boyadjieff G. I. , Merit M. A. 
Published: December 2007

Summary
Rig automation projects can benefit from the experiences developed during the successful automation of rig pipe-handling equipment. The data provided were derived from the operation and development of iron roughnecks and pipe-handling systems in the field. This paper includes a study of failure mechanisms and how they affect reliability, presents maintenance experiences to show the impact of automation on crew capability and training, and describes many operational and design pitfalls.
A Method for Handling Gas Kicks Safely in High-Pressure Wells
Authors: Low E. , Jansen Case 
Published: December 2007

Summary
The risk of overloading an atmospheric mud/gas separator (MGS) during high-volume gas kill operations can be minimized. This paper presents the theory and procedure for minimizing this risk for high-temperature/high-pressure (HT/HP) wells. The method can be used to set criteria for selecting the kill method and for separator sizing.

Introduction
The number of HT /HP wells being drilled in the North Sea has increased rapidly. Pressures &gt;15,000 psi are common with associated temperatures&gt;350°F. The drilling and exploitation of these reservoirs have been described as the new challenge to the drilling industry. However, serious well-control incidents have compelled the industry to re-examine the equipment and procedures used to drill these wells.
This paper examines a major shortcoming identified recently: the ability of rig equipment to separate and vent large gas volumes from mud safely. Venting rates from kicks in high-pressure wells can approach the equivalent production of a commercial gas well.
If the separator is overloaded, gas will be blown back into the shale shaker room and other mud-processing facilities, creating an extremely hazardous environment with a high explosion risk. Also, live crude, condensate, and drilling mud will be expelled by the gas through the gas vent line. On offshore rigs, where the vent line often discharges at the top of the derrick, the liquids will fall back to the drilling rig or platform. This creates a fire or explosion hazard. The volatile condensate/oil mixture will accumulate close to the deck in any void space and can be ignited by a spark. The hazards of MGS blowdown are apparent.
High reservoir pressures and temperatures increase the surface gas volume per unit volume of gas influx. The ability of rig gas-processing equipment to handle such increased volumes concerns the industry. Normal practice does not take into account the limitations of the separator but instead concentrates on well control, assuming that the MGS can handle whatever gas volume is present.
The problem is clear. As we continue to explore for oil and gas in deeper and higher pressure reservoirs, we often exceed the safe operating limits of the MGS. Separator modification and redesign has improved its capacity considerably, but space restrictions, especially on mobile rigs, impose an inherent limitation. Our lack of understanding of the complex separation process has done little to improve operating procedures and practices.
Computer Simulation of the Reverse Circulation Well Control Procedure for Gas Kicks
Authors: Miska S. , Beck F. E. , Murugappan B. S. 
Published: December 2007

SummaryA computer simulator was developed and used to evaluate reverse circulation as a potential well-control procedure during drilling. Potential advantages of reverse circulation verified by the simulator include lower casing pressures and smaller cumulative pit gains. In addition, kick fluids are removed from the well much faster than with conventional kill procedures. Several equipment modifications will be required to implement the reverse-circulation kill procedure.
Installation of STAR Platform
Authors: Søgaard Preben , Lytzen Peter 
Published: December 2007

Summary
During late Summer 1990, Mærsk Oil & Gas A/S installed the first slim tripod adapted for rig (STAR) satellite platform in Dagmar field in the North Sea by means of a jackup rig. This installation successfully completed the STAR project, and this paper describes the planning and actual installation of the Dagmar satellite platform, a concept that is fully applicable worldwide where a small wellhead platform is needed in shallow water and where crane barges are not readily available.
Underground Flow Well Control: The Key to Drilling Low-Kick-Tolerance Wells Safely and Economically
Authors: Wessel Michael , Tarr Brian A. 
Published: December 2007

Summary
The minimum acceptable kick tolerance can be quantified on the basis of the likelihood and consequences of an underground-flow well-control incident. Safe and economical casing points can be selected on the basis of the minimum acceptable kick tolerance required to drill the next hole section. For sections with a known but manageable underground flow potential, necessary unconventional well-control contingency plans can be developed. This new approach to well control has the potential to reduce drilling costs by significantly reducing the likelihood of major drilling-related well-control incidents.
Use of Advanced Pattern-Recognition and Knowledge-Based System in Analyzing Dynamometer Cards
Authors: Schirmer P. , Gay J. C. , Toutain P. 
Published: December 2007

Summary
A quick and accurate identification of downhole problems is essential in rod pumping to minimize operating costs and to maximize oil production. TOTAL-CFP developed a system to assist engineers in day-to-day oilfield operations in rod pumping. The system will make rod-pumping expertise available to field operations personnel. It provides a tool for improving data analysis and can be used as a training aid for engineers dealing with rod-pumping wells for the first time. This system has three subsystems: a dynamogram acquisition system, a dynamogram management system, and a knowledge-based system.
This paper presents the knowledge-based system, which is used to diagnose downhole problems and to suggest corrective actions. To achieve these goals, the system applies advanced pattern-recognition techniques that consist mainly of structural pattern-recognition methods and hierarchical data structures called quadtrees. The diagnostics and recommendations are based on the analysis of surface dynamometer and downhole cards. The interface between the user and the system is very friendly. The system provides the user with graphical explanations of its diagnostics. The system prototype was installed in March 1991 and the specifications of the final version are planned for the end of this year.
Concrete Structures for Development of Offshore Fields
Authors: Gudmestad O.T. , Warland T.A. , Stead B.L. 
Published: December 2007

Summary
Concrete structures represent competitive solutions for developing many offshore fields. They are of particular interest when storage is required and as floating support structures. Furthermore, concrete reusable platforms may represent cost-saving solutions for many applications. To design optimum structures, designers must be realistic with respect to the structural capacity of concrete for offshore use.

Introduction
Experience in the North Sea has shown that concrete support structures are competitive with steel jacket structures in terms of initial investments and maintenance costs. This experience is considered relevant for other areas, particularly for countries that must import steel, for icy areas, for offshore areas without infrastructure, for places where oil storage facilities are required, and for areas where large crane vessels are not available to lift heavy steel structures or large topside modules. Furthermore, concrete floaters [tension-leg platforms (TLP's) and catenary anchored structures] are attractive as minimum-cost solutions for deepwater applications.
This paper discusses the requirements and infrastructure needed to design and fabricate concrete structures. Particular attention is given to availability of cement, aggregate, reinforcement steel, and prestressing cables. This paper also discusses design competence and required computer facilities, as well as the availability of barges, a shipyard dock, or a special-purpose construction dock. We describe the fabrication, installation, and removal processes. Removal is becoming increasingly important in a world gradually becoming more aware of environmental stability. We give examples of efficient designs suitable for optimum development of small fields and fields requiring storage. These examples include traditional concrete structures constructed with form work or slip forming. Furthermore, novel concrete truss structures fabricated by joining precast tubes and nodes by prestressing cables and grout are discussed. We provide charts that give concrete volumes for a range of applications to enable operators to perform their own economic analyses.
Development Drilling Problems in High-Pressure Reservoirs
Authors: French F.R. , McLean M.R. 
Published: December 2007

Summary
The successful drilling of a well relies on the correct choice of mud weight after consideration of the collapse and fracture gradients in each hole section. Collapse and fracture gradients and the formation pressure determine the allowable mud weight that can be used to drill a formation. Here, attention is focused on the fracture gradient and its interpretation and variation with hole orientation. We show that interpretation of the fracture gradient in exploration and appraisal wells may not be sufficient to evaluate development options safely. We give a case study of a central North Sea over pressured reservoir to highlight this problem. We conclude that the industry needs to consider the use of microfracturing to resolve the uncertainty inherent in planning development wells in overpressured reservoirs.

Introduction
The successful drilling of a well relies on good planning and consideration of many factors, including mud weight. Historically, mud weight was chosen primarily to prevent the influx of formation fluids. Over the past 2 decades, much attention has been given to the role of mud weight in preventing hole collapse and its adverse effect on inducing mud losses. Fig. 1 depicts extreme wellbore instability conditions where an insufficient mud weight leads to hole collapse because of compressive wellbore failure and too high a mud weight leads to formation breakdown because of tensile failure. Historically, hole collapse and unintentional fracturing have been considered in wellbore stability studies. The majority of published literature has focused on prediction and prevention of hole collapse. Although we discuss hole collapse, our primary focus is the fracture gradient.

Minimum Static Mud Weight
The minimum static mud weight required to drill a well is the larger of the static mud weight required either for well control or to prevent compressive wellbore failure.
The static mud weight required for well control is equal to the formation pressure plus a safe overbalance. The minimum safe overbalance is generally accepted to be 200 psi.
Determining Pump Wear and Remaining Life From Electric Submersible Pump Test Curves
Authors: Divine D. L. , Lannom R. W. , Johnson R. A. 
Published: December 2007

Summary
The remaining useful life of an electric submersible pump (ESP) is an important economic consideration in deciding whether the used pump should be returned to service without repair. This paper presents quantitative and qualitative techniques to determine the type and amount of wear that a pump has experienced from analysis of pump test data. This paper discusses methods of categorizing used pumps, depending on the wear and associated performance deterioration. This work also describes failure modes, pump reliability, and the concept of pump (product) infant mortality. We show that a used pump can be more reliable and have a longer run life than a new or rebuilt pump. We use test data, tear-down analysis, and a case history to develop these concepts.
Aquifer Behavior with Injection
Authors: Bonet E.J. , Crawford Paul B. 
Published: December 2007

The injection of water at substantial distances from the oil-water contact may cause only 10 to 50 percent of the injected water actually to advance the oil-water contact. The remainder of the water serves to increase the pressure in the aquifer, and its effect is dissipated in the pore volume-compressibility term.

Introduction
It is fairly common practice to reinject water into the aquifer near the oil-water interface in water-drive reservoirs. There have been many studies of aquifer behavior without reinjection, but apparently no analytical studies have been made to indicate performance when injection wells are present in the performance when injection wells are present in the aquifer.
The diffusivity equation may be used to describe the pressure behavior in an aquifer. When sources are present it can be written as present it can be written as(1)
A general solution of Eq. 1 may be obtained as the sum of two solutions. One is a general solution of the homogeneous equation, obtained by dropping the source term in Eq. 1 and still satisfying the required boundary conditions. Another is a general solution of Eq. 1 satisfying homogeneous boundary conditions. The first solution, which corresponds to the aquifer without reinjection, has been given quantitative and qualitative treatment in the literature. The latter solution will be treated here.
Solutions with variable injection rates are obtained by superimposing solutions with constant rates, so we have considered only the latter.
Five cases have been treated here:
A linear aquifer of finite width and extent. Water is injected into the aquifer at point xo, yo at constant rate. The pressure along the line x = 0 is maintained at zero pressure. (See Fig. 1.) Equations showing the pressure distribution, rates, velocity and cumulative pressure distribution, rates, velocity and cumulative influx have been developed. Certain numerical results are shown. A linear aquifer of finite width and extent. Water is injected into the aquifer at point xo, yo at constant rate. The rate of production along the oil-water water contact is maintained constant. Equations showing the pressure distribution inside the aquifer are presented. pressure distribution inside the aquifer are presented. A linear aquifer of finite width and extent. Constant pressures are maintained at opposite ends of the aquifer. Water is injected at constant rates at point xo, yo. Equations showing the pressure distribution are shown. A linear aquifer of finite width and infinite extent. The pressure is maintained constant at the oil-water contact. Water is injected at a constant rate at point xo, yo. A linear aquifer of finite width and finite extent. The pressure at the oil-water contact is maintained constant. Water is injected at constant rate per unit length along a fine xo.

The Linear Aquifer
The linear closed aquifer, performing at constant terminal pressure was selected as the first case to be analyzed. The development of the equations is based on uniform injection per unit of thickness, and gravity effects are neglected.
JPT
P. 1210
Effects of PDC-Bit Selection and Mud Chemistry on Drilling Rates in Shale
Authors: Hemphill Terry , Clark R. K. 
Published: December 2007

Summary
Full-scale drilling tests were run to evaluate the effect of mud chemistry on penetration rates in Pierre shale cores. Two poly crystalline-diamond-compact (PDC) bits and nine different muds were used in the tests. In addition to penetration rate, occurrence of bit balling with a given mud type was studied. Results indicate that bit type and mud chemistry affect penetration rates and bit balling significantly.
Enhancement of In-Situ Combustion by Steam Stimulation of Production Wells
Authors: Galas C. M. F. , Ejlogu G. C. 
Published: December 2007

Summary
Steam stimulation of individual wells was used to improve the performance of an in-situ combustion project operated by BP Resources Canada Ltd. in the Cold Lake oil-sand deposits of northeastern Alberta. In addition, steam was used to protect production wells that were threatened by the combustion front or had experienced oxygen breakthrough. The effectiveness of these steam uses varied. This paper describes the strategy developed for the use of steam injection and case histories and draws conclusions on how to use steam injection for maximum effect.
Long-Term Production Results of Polymer Treatments on Producing Wells in Western Kansas
Authors: Moffitt P.D. 
Published: December 2007

Summary
This paper describes the analysis of the long-term oil production performance of 37 near-well polymer treatments on 26 producing wells in western Kansas to determine incremental oil recovery resulting from the treatments. Estimated incremental oil recovery from the 37 treatments was 76,500 STB of oil from 39,600 Ibm of polymer injected, or 1.93 STB/lbm of polymer injected. The polymer treatment types giving the best oil recovery performance were solutions of anionic polyacrylamide (ungelled) and cationic polyacrylamide gelled in situ with the chromium reduction/oxidation process. Both gave incremental oil recoveries of 2.6 STB oil/Ibm of polymer injected and had average treatment lifetimes exceeding 1 year.

Introduction
Polymer treatments of injection and production wells have been used extensively for fluid diversion and to increase oil recovery. Injection of high-molecular-weight polymers increases the viscosity of the injected water and reduces the permeability of the porous medium to water. In producing-well treatments, the injected aqueous polymer solution preferentially flows into zones that exhibit high permeability to water and subsequently restricts the flow of water when the well is put back on production. Polymer injection has two effects: the water production rate decreases substantially and the pressure drawdown into the wellbore often increases greatly, resulting in an increased oil production rate.
During the 1970's, Phillips Petroleum Co. conducted 37 polymer treatments on 26 producing wells in western Kansas. All but one of the treatments were on wells completed in the Arbuckle dolomite formation. The formation has been characterized as a highly fractured, vuggy dolomite with varying amounts of chert and with reservoir characteristics varying from field to field throughout the Central Kansas Uplift. Permeability ranges from 50 to 5,000 md; porosity ranges from 1% to 20%, with an average of 15%. The oil zone is estimated to be 5 to 50 ft thick; the total Arbuckle zone is up to 300 ft. Oil viscosity ranges from 3 to 13 cp. The reservoir drive mechanism is primarily bottomwater drive, and the wells are completed at the top of the formation to delay the onset of water production. Water production comes primarily from coning. Because of the natural fracture network, vertical permeability is high and there are few vertical barriers to restrict water coning.