bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Well-Stimulation Results in a Gas-Storage Field in the Absence of Reservoir Data With Neural Networks
Authors: Mohaghegh Shahab , McVey Dan , Aminian Khashayai , Ameri Sam 
Published: December 2007

Summary
Selection of candidate wells for stimulation treatment to increase their productivity is a challenging task. A systematic approach that uses a three-layer backpropagation neural network, introduced in this paper, assists engineers in predicting post-stimulation well performance to select candidate wells for stimulation treatment. This approach can also be used to optimize the stimulation design parameters. Unlike conventional simulators that are based on mathematical modeling of the fracturing process, the process introduced in this paper uses no specific mathematical model. As a result, access to explicit reservoir data, such as porosity, permeability-thickness, and stress profile, is not essential. This is a major advantage over conventional hydraulic fracturing simulators, which can translate to considerable savings because it eliminates the need for expensive data collection. The application of this methodology to a gas-storage field is presented in this paper. The developed neural network can predict the postfracture well deliverability with approximately 95% accuracy. These results were achieved in the absence of reservoir data (permeability, porosity, thickness, and stress profiles) that makes conventional fracture simulation impossible. This process is currently being used to select candidate wells for future stimulation treatment in the aforementioned field.
A New Drillpipe Design Virtually Eliminates Failures That Result From Slip Damage
Authors: Wilson G. E. 
Published: December 2007

Summary
Drillstrings made before 1982 were not designed to meet the rigorous demands of today's drilling. Deeper wells and higher-angle holes are requiring higher pump pressure, and more tensile and torque capacity. Back-reaming, with the use of a power swivel, is agitating these conditions even further.
Recent work has been done to improve the fatigue life of drillpipe by making drillpipe with longer internal-taper upsets and stress-relief grooves.
Even though improvements have been made, slip damage still takes its toll on drillpipe. This paper addresses the failures caused by slip damage and offers a solution for solving this problem. Finite element work and fatigue testing has been done to prove the effectiveness of this new drillpipe design.
Wellbore-Stability Analysis Made Easy and Practical
Authors: Santarelli F. J. , Zaho S. , Burrafato Giovanni , Zausa Fabrizio , Giacca Diego 
Published: December 2007

Summary
Recent years have seen much scientific and technical progress in the understanding of wellbore stability. The main causes of instabilities have been identified, models have been developed, and practical remedies proposed and often tried successfully in the field. Yet despite this scientific effort, extra drilling costs associated with well-bore instabilities remain very high. This demonstrates that until now, scientific and technical progress has somehow failed to reach final technical and economical objectives.
This paper shows that the main reason for such a state of affairs is the complexity of wellbore-stability analysis, which cannot be performed for every single well on a worldwide basis. Having identified this, Agip undertook a vast effort of field-data back analysis to identify from historical records the best way to optimize its drilling planning, practice, and post-evaluation procedures. The paper presents part of this effort and in particular the back analysis of four clusters drilled in southern Italy (a total of 38 wells). It then draws conclusions for procedure optimization. Finally, it shows how the approach is used during the field-appraisal phase to speed up the learning curve and significantly cut the development-drilling costs.
An Analysis of Weep Holes as a Product Detection Device for Underground Compensated LPG Storage Systems
Authors: Sarica C. , Demir H. M. , Brill J. P. 
Published: December 2007

Abstract
Weep holes have been used widely to detect the presence of Liquefied Petroleum Gases (LPG) in brine for underground compensated storage systems. When the brine level drops below the weep hole, LPG product enters the brine production system causing an increase in both tubing head pressure and flow rate. To prevent cavern overfill, a cavern shutdown is initiated upon detection of LPG in the surface brine system by pressure or flow instruments at the tubing head.
In this study, we have investigated the multiphase flow characteristics of weep hole LPG detection systems to correctly estimate the operating limits. A simple and easy to use model has been developed to predict the tubing head pressure and flow rate increases. The model can be used to implement safer and more efficient operation procedures for underground compensated LPG storage systems.
The model predictions for a typical field case are presented. An analysis of weep holes as product detection devices for LPG storage reservoirs has been carried out. It was found that the increases in pressure and flow rates at the tubing head change as a function of injection flow rate of the product. Therefore, a thorough consideration of cavern operating parameters is necessary to evaluate the use constant pressure and flow rate values to initiate emergency shut down of the cavern.
Underbalanced Coiled-Tubing Drilling Experience on the Ula Field
Authors: Weighill Geoffrey , Thoreby Helge , Myrholt Lars 
Published: December 2007

Summary
Underbalanced coiled-tubing drilling was identified as the best method to access additional reserves in the Ula oil field. The first operation involved deepening a live well through the existing production tubing with flow routed to the platform facilities. This was carried out simultaneously with other platform activity and the technical challenges, operational experience, and drilling performance are described. The operation was ultimately successful and the new hole section presently contributes an additional 700 STB/D of oil to the field production.
Rigless Multizone Recompletion Using a Cement Packer Placed With Coiled Tubing: A Case History
Authors: Nowak T. W. , Patout T. S. 
Published: December 2007

Summary
Cement packers have been used for some time when reserve estimates have not justified the cost of major rig remedial work. They typically provide a means of zonal isolation of the last reserves in an existing wellbore. The success of these operations has historically been low. This is predominantly because of poor cement bonding in the annulus between the tubing and production casing. Because of the minimal amount of equipment on location and lack of upfront design work involved, most cement packers are doomed to failure before they are even placed. Cement packers have been placed using a large number of methods. In the Ship Shoal 181 field, Well B-4 would not economically justify a major rig workover, even though there were several uphole gas sands capable of producing in this well. With proper upfront planning and design, it would be economical; however, all these reserves could be produced in a through-tubing process using a cement packer.
This case history presents a refined look at existing technology involving placement of a cement packer and reviews problems common to cement-packer completions, including a case history. Solutions are also discussed for successfully completing and recovering reserves from not one but several remaining gas intervals. This paper reviews the design considerations and precautions, along with the production results and economics, for placing what is believed to be the largest cement packer placed through coiled tubing.
New pH-Buffered Low Polymer Borate Crosslinked Fluids for Hydraulic Fracturing
Authors: Nimerick Kenneth H. , Temple Harry L. , Card Roger J. 
Published: December 2007

Summary
The utilization of low concentrations (15 to 20 lbm/1000 gal) of borate-crosslinked guar has not been successful in the past because of the inability to effectively control the pH and B(OH)−4 concentration of the fluid. Today's new pH buffer technology allows the use of low concentrations of guar at temperatures up to 210°F. These new pH-buffered borate-crosslinked guar fluids can be effectively utilized at temperatures up to 240°F by increasing the polymer loading. Due to the lower achievable polymer loading and relatively low pH, these new pH-buffered borate fluids possess excellent cleanup and retained proppant conductivity. In field documented cases, well cleanup times have been reduced by more than half. Laboratory conductivity tests show that these pH-buffered fluids, utilizing reduced polymer loading, produce retained conductivity values of 10 to 25% (absolute) higher than alternative conventional borate-crosslinked fluids incorporating higher polymer loading.
Produced-Water Treatment Technology— A Study of Oil/Water Separation in Gravity-Type Crossflow Pack Separators for Qualitative Separation
Authors: Kenawy F. A. , Kandil M. E. , Fouad M. A. , Aboarab T. W. 
Published: December 2007

Summary
To handle ever-increasing oily water volumes and to improve water quality discharge, separation equipment should be developed to meet industry demand and match environmental regulations. However, special constraints such as size, simplicity of operation, variable fluids, different operating conditions, and economics warrant special emphasis. Therefore, the study of traditional gravity-type oil/water separation equipment is essential to enhance the separation process and maximize its effectiveness. This will become increasingly important as environmental regulations become more stringent in the future. This paper, trying to meet this target, presents a modified design for the standard crossflow pack (CFP) separator. The new added development to the design of the separator incorporates a mechanism whose function will be forwarded to provide a shaking motion to its stationary plate pack. This mode of operation has the potential to improve oil/water separation, minimize the plugging tendency of the plates, and consequently maximize the effectiveness of the crossflow pack separator.
The obtained results revealed that the effectiveness of the cross-flow pack separator had been increased because of the shaking of its plate pack, and it reached its peak value at the flow Reynolds number (based on the hydraulic diameter as the characteristic length) equivalent to 1,830. On average, the CFP separator removed all oil particles greater than 30 ßm for streams whose oil-in-water concentration was greater than 150 ppm.
Therefore, it can be demonstrated that providing a shaking motion to the traditional CFP separator has an appreciable potential to improve oil/water separation. Continuing research is encouraged, to ensure the establishment and achievment of proper scientific criteria for the CFP separator.
Collapse Pressure of Coiled Tubing Under Axial Tension
Authors: Yang Yong S. 
Published: December 2007

Summary
As the coiled tubing is cycled on and off the reel and over the gooseneck, initially nearly perfectly round CT becomes oval. This ovality significantly decreases the collapse failure pressure as compared to perfectly round tubing. An analytical model of collapse pressure for oval tubing under tension load is developed based on elastic instability theory and the von Mises criterion. The theoretical model shows satisfactory agreement with experimental data for 3.5" OD and 0.190" wall thickness tubes with small ovality.
The Effect of Fluid Flow on Coiled-Tubing Reach
Authors: Bhalla Kenneth , Walton I. C. 
Published: December 2007

SummaryA critical parameter for the success of many coiled-tubing (CT) operations in highly deviated or horizontal wells is the depth penetration that can be attained before the CT buckles and locks up. Achieving a desired depth is always critical in CT operations, and attaining an additional reach of a few hundred feet can be crucial. This paper addresses the effect of fluid flow in the CT and in the CT/wellbore annulus on the state of force and stress in the CT, and thereby predicts its effect on the reach attainable by the CT.The flow of fluid through the CT and the annulus between the CT and the borehole modifies the pressures and the effective force that govern the mechanical stability of the CT. The net force per unit length caused by fluid flow in the CT and annulus between the CT and casing/well is calculated in terms of the shear stress, and its effect on the onset of buckling and lockup is determined. A model is then implemented in a full-tubing-forces calculation, and the effect of flowing fluids and producing fluids on reach is analyzed. The new model is used in desiging commercial jobs.The exact analytic model shows that fluid flow inside the CT has zero impact on reach, that downward flow in the annulus has a favorable impact, and that upward flow in the annulus reduces the maximum attainable reach.A CT job can be designed using the full-tubing-forces model, taking into account the flow of a fluid with a specified rheology, density, and flow rate. Thus, the feasibility of attaining a given reach can be more accurately determined. Results are presented in the form of the surface weight for commercial wells and are compared to field jobs.
Measurement of Oil and Water Flow Rates in a Horizontal Well With Chemical Markers and a Pulsed-Neutron Tool
Authors: Roscoe B. A. , Lenn C. P. , Jones T. G. J. , Whittaker A. C. 
Published: December 2007

Summary
A new approach to obtaining oil and water flow rates in producing horizontal wells has been developed with a pulsed-neutron tool (PNT). This approach uses separate measurements of oil and water velocities in combination with separate holdup measurements to obtain the flow rates.
The velocity measurement uses water-soluble and oil-soluble chemical markers, both of which are insoluble in the other fluid phase for the measurement. The markers are injected into the borehole by a logging tool at one location and detected by a PNT at a second location. The transit time between injection and detection of the marker gives a measurement of the fluid velocity. Because the markers are soluble in only one phase, the velocity of each phase can be measured separately. This measurement has been made under both laboratory and field conditions to measure velocities from 10 to 500 ft/min at horizontal and several degrees deviation from horizontal. The results of these tests show good linearity and repeatability of the measurement.
The holdup measurement is performed with the inelastic data from a PNT. With these data, it is possible to obtain quantitatively the holdup of all three phases by combining information from the inelastic near/far (N/F) ratio with the near and far carbon/oxygen (C/O) ratios. This approach to the holdup measurement has been demonstrated by use of a combination of laboratory data, Monte Carlo modeling, and field data. The results of this study have demonstrated that the root-mean-square (RMS) accuracy of this measurement is about 6% on each of the three phases.
Hydrocarbon Management—Surface Processing Facilities in the Prudhoe Bay Field of Alaska
Authors: Chambers M. J. , Eager K. D. , Mattison S. A. 
Published: December 2007

Summary
Facility debottlenecking and corrosion/erosion repairs are costly penalties being paid today for previous design decisions. These decisions were made without correctly anticipating long-term changes in the field production profile. This manuscript addresses specific problems at the F-Pad production facility, located in the western operating area of the Prudhoe Bay field on the north slope of Alaska. These problems resulted from a lack of long-term planning on prior well-pad-expansion projects. This manuscript addresses present problems and impacts, current fixes and lessons learned, proposed solutions and benefits, and forward-looking designs.
Past facility-expansion projects on F-Pad have proved to be a liability today. Short-term economic decisions made during low-oil-price environments in the past have caused corrosion/erosion problems and introduced high surface flowing pressures as the production trends of the wells on the pad changed. Two major facility-debottlenecking projects have been required to address these problems and to accommodate new well additions to the pad. Many patches, repairs, and flowline swaps have also been required. A post-mortem of the completed debottlenecking Phase One project will be provided, including descriptions of the problem, solution, scope of work, expected cost and benefits, and measured benefits. The lessons learned will be presented in the form of the proposed debottlenecking Phase Two plans and the best design options for future new well expansion of well pads in the Prudhoe Bay field.
Information provided in this manuscript can lead directly to better long-term planning for production-well-facility-expansion projects. Longer-term thinking can prevent building-in limitations that cannot handle changing production trends, that can reduce facility life because of corrosion/erosion conditions, and that may prevent value-added future expansion projects.
The Effect of Sulfur Deposition on Gaswell Inflow Performance
Authors: Roberts Bruce E. 
Published: December 2007

Summary
Deposition of solid elemental sulfur in the formation may significantly reduce the inflow performance of sour-gas wells. The key operational and reservoir parameters that influence the magnitude of impairment by sulfur deposition were identified through the derivation of an analytical expression for the rate of sulfur buildup assuming idealized flow conditions. A methodology for the use of conventional, black-oil reservoir simulators was subsequently developed to permit the investigation of sulfur-deposition processes for specific reservoir descriptions and well operations. The rate of sulfur buildup in the formation was shown to be inversely proportional to the square of the radial distance from the well. As a consequence, the magnitude of sulfur deposition is highly sensitive to well skin— the lower the skin, the farther away from the well the deposition occurs and the lower the sulfur-buildup rate. Nonuniform deposition over the pay interval (owing to reservoir layering or uneven stimulation) was shown to accelerate the impact of sulfur deposition. A field case involving early decline in well production caused by sulfur deposition was successfully history-matched with the simulation model developed in this study.
Popeye Project: An Overview
Authors: McLaughlin D. C. , Alford B. J. 
Published: December 2007

Summary
This paper presents an overview of the Shell Offshore Inc. (SOI) Popeye project, a remote subsea gas development in 2,040 ft of water in the Gulf of Mexico (Refs. 1 through 4 contain additional technical details on the project). Planning and execution of the project required a balance throughout between proven methods, cost reduction, requirement for extending technology, and the desire to develop a system which could be used as a stepping stone to future deepwater prospects. Popeye was successfully installed and started up in January 1996. It represents application of an innovative, yet cost-effective, field development system that advanced the state of deep-water subsea technology.
A Pore-Level Investigation of Relative Permeability Hysteresis in Water-Wet Systems
Authors: Dixit A. B. , McDougall S. R. , Sorbie K. S. 
Published: December 2007

Summary
Oil-recovery efficiency is known to depend crucially upon the surface chemistry of the particular crude oil/brine/rock system under investigation. Mineralogy, brine chemistry/pH, crude-oil composition, and ageing conditions all serve to modify the effective contact angles operating within a mixed-wet, porous medium. Recent network-modeling studies have helped to clarify the important role played by wettability during multiphase flow in nonuniformly wet systems. The consequences of modified-contact angles during waterflooding have been described in terms of various regimes. These have, subsequently, been used to reconcile a wide range of apparently contradictory wettability experiments.
The purpose of this paper is to apply these ideas to the study of hysteresis phenomena in both strongly and weakly water-wet, drainage/imbibition, relative permeability curves. Such hysteresis effects have long been recognized, but the precise direction of hysteresis seems to vary from study to study. Indeed, in water-wet media, even the degree of sample consolidation appears to play an important role.
A three-dimensional (3D) network model is reported, which takes into account a great deal of the underlying pore-scale physics. Initial water saturation, wettability alterations, film flow, phase trapping, and realistic variations in advancing and receding contact angles are all incorporated into the simulations.
More specifically, this study examines relative permeability hysteresis in systems from Regime IA, which corresponds to strongly and weakly water-wet, porous media (i.e., media where some degree of modification in the distribution of effective contact angles has occurred). The consequences of different combinations of pore-scale-displacement mechanisms (viz., snap-off and piston-like displacement) for relative permeability hysteresis has been calculated by means of the pore-scale simulator. The effects of combining these mixed mechanisms with other network properties, such as coordination number (z) and certain volume and conductivity exponents (ν and λ), are also reported. The nature of hysteresis is found to change quite dramatically as these parameters are varied, and all experimentally observed trends in relative permeability hysteresis are reproduced under suitable conditions. This may be the first time that a pore-scale model has been used to provide a clear interpretation of all experimentally observed hysteresis trends during primary drainage (PD), secondary imbibition (SI), and secondary drainage (SD) displacements in both strongly and weakly water-wet systems.
A New Interpretation Model for Fracture-Callbration Treatments
Authors: Fan Yong 
Published: December 2007

Summary
This paper introduces an interpretation model for fracture-calibration tests conducted in both low- and high-permeability reservoirs. The model is based on a detailed description of fluid flow into the porous medium with considerations of variable filtercake, non-Newtonian invasion effects, and superposition of fracture pressure. The leakoff rate is determined by the pressure profile instead of presumption of leakoff mode. This work, incorporating mass balance with principles of fluid and solid mechanics, provides a straight-line technique for determining formation permeability and fracture filtercake resistance. The determined pressure drops from the fracture face into the reservoir allow the separate computation of the compressibility-controlled component of leakoff and the combined filtercake and non-Newtonian invasion components. Leakoff is pressure-dependent.
Case studies of actual treatments are provided to demonstrate the new model and its interpretation. Comparisons are made to elucidate the similarities and differences between the traditional method and the new method. The new method accounts for fluid leakoff more accurately, allows for better fracturing design, and is particularly attractive for the tip screenout fracturing (frac-pack) treatments conducted in medium-to-high permeability formations.