bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Behavior and Design of Offshore Caissons
Authors: Hong S.T. , Brooks J.C. 
Published: December 2007

Abstract
Free-standing caissons are used for supporting flare pipes and single-well production platforms. However, caissons tend to be flexible and dynamically sensitive, and the static design practice may not be adequate for this type of practice may not be adequate for this type of structure. To assess motion effect on the integrity of the structural system and to quantify the allowable motion for safe operation on board a caisson platform, analytical and experimental studies of platform, analytical and experimental studies of the dynamic behavior of a caisson structure were conducted and are described here. The analytical simulations agree well statistically with The motion measurements.
A caisson design procedure considering dynamic effects was developed Design considerations include ultimate strength failure, fatigue failure, excessive motion, and possible damage during installation. A key feature in an effective caisson design is that the upper part of the caisson should be made as small as possible so that wave loading and the caisson period can be minimized The fatigue design procedure was verified with past caisson operational experience. To illustrate past caisson operational experience. To illustrate the procedure, a flare-pipe support caisson in 185 ft of water was designed and analyzed.

Introduction
Free-standing caissons are used for supporting flare pipes or single-well production platforms. The attractiveness of a caisson structure lies in the potential economy and the short time required for potential economy and the short time required for fabrication and installation. However, a caisson tends to be flexible, and dynamic effects may increase the design requirements from both strength and functional standpoints. To assess the motion effect on the integrity of the structural system and to quantify the allowable motion level for effective operation on board a caisson platform, analytical and experimental studies of the dynamic behavior of a caisson structure were conducted, and a procedure was formulated for designing a caisson considering dynamic effects. Observations from the experimental data and computer simulations of the caisson behavior are described. Verification of the computer simulation and some useful information for developing and using such simulations as well as practical interpretation of the analytical results practical interpretation of the analytical results also are given. Differences between a static design and a dynamic design are illustrated in an example design of a flare-support caisson in 185 ft water.

MOTION MEASUREMENT
Motion data were taken from a caisson platform offshore Louisiana. General dimensions of the caisson are shown in Fig. 1.
SPEJ
P. 291
Optimum Fractures in High-Permeability Formations
Authors: Morales R. H. , Norman W. D. , Ali S. A. , Castille C. T. 
Published: December 2007

SummaryThis paper describes an analytical model that (1) designs the pumping schedule of tip-screen-out (TSO)(frac-pack) fractures for high- and low-permeability formations, (2) estimates the reservoir production, and (3) determines the optimum propped length using the net present value concept. Sensitivity studies show the influence of the proppant permeability to propped fracture width. Sensitivity runs also show the influence of drainage area (and formation permeability) to optimum fracture length. A field example demonstrates the benefits of an appropriate fracture design.
Tax Considerations in Various Oil Transactions
Authors: Bullion J. Waddy 
Published: December 2007

Introduction
This paper considers tax aspects of transactions involving production payments. In addressing engineers, it is fitting and proper that the terms be first defined. What is a production payment? It is essential that a production payment be dischargeable only out of runs accruing to a property and the holder of the payment must look exclusively to the proceeds of the sale of production accruing to the payment for its satisfaction and liquidation. It is also essential that the payment be of limited duration - that it not last for the life of the property or properties. The payment in most instances is free and clear of all costs of operation and development and is dischargeable out of a specified fraction of the runs. The size of this fraction will vary, depending, in part, upon the nature of the transaction involved. A production payment is normally payable out of a stated percentage of the runs until from the sales proceeds of such runs there has been paid a specified sum of money. The amount of a payment may also be stated in terms of barrels of oil or cubic feet of gas. It is possible to create a true production payment which is based on neither a dollar amount nor units of production. Such a payment would have attributed to it a specified percentage of the net proceeds from the operation of the properties and would terminate when the remaining reserves under the properties reach an agreed percentage of total reserves.

Types of Production Payments
What are the kinds of production payments? Basically there are two types of production payments - the reserved payment and the carved out payment. A reserved payment is created where the owner of a property or properties assigns all of his leasehold or working interest to another and in such assignment reserved to himself a production payment.
A carved out payment is one which is assigned out of a larger depletable property; for example, if A, the owner of an oil and gas lease, assigns to B 75 per cent of the runs accruing to such lease unit B has received from the proceeds of the sale of such runs the sum of $100,000, A has carved a payment out of his leasehold estate. There are two types of carved out payments.
Quantifying Drilling Efficiency and Disruption: Field Data vs. Theoretical Model
Authors: Putot C. J. M. , Guesnon Jean , Perreau P. J. , Constantinescu Andrei 
Published: December 2007

Summary
Mechanical and kinematics data at the bit have been collected during drilling operations and organized to identify optimal drilling efficiency. Transitional conditions towards abnormal behavior have been distinguished. Normal drilling is usually characterized by regular linear relationships between global control variables at the bit, which approximately correspond to an upscaling of a local Mohr-Coulomb-type failure mechanism of the rock. Most of our experimental data confirm this classical disposition. However, considerable departure from these relationships is noted, especially when there is bottomhole assembly (BHA) resonance or when there is partial balling at the bit. The field tests presented here allow us to verify classical theory and to draw up new guidelines for behavior in nonoptimal or dangerous, evolving operating conditions, such as those that occur under poor cleaning conditions. The main features of a mechanical structuring model involving transition towards low-efficiency conditions are presented, and it is shown how this model confirms our interpretation of field data. The model couples the drillability of rock and the general dynamics of the bit in an original and synthetic way. It makes it possible to understand and test the sensitivity of bit response to variables such as "weight on hook," torque on the drillstring, and flow rate of the fluid.
Unique PDC Bit Technologies Combine To Reduce Drilling Time in Interbedded Formations
Authors: Taylor Steven , Besson Alain , Minto Djoko , Mampuk I. S. 
Published: December 2007

Summary
Interbedded formations cause difficulty when selecting a drill bit for optimum section performance. Hard stringers require bit features that conflict with those required for softer homogeneous formations. Limited by conventional technology, this culminates in the selection of a bit too heavy set to maximize penetration rates through the soft formation or too light set to drill the hard stringers. This paper describes a unique combination of PDC bit technologies that provide a solution to consistently drill interbedded formations without compromising bit selection. The unconventional design consists of features to maintain high-penetration rates in soft formations and the stability and life required to pierce through hard stringers.
The technologies are combined on a steel bit body. The nature of this material allows its fundamental engineering properties to be exploited to produce extreme features that cannot be achieved using matrix powder technology. This material is the cornerstone that expands the design and manufacture windows for conventional PDC bit technologies.
Soft formations imply high-penetration rates: the technologies developed are a novel hydraulic arrangement, bit face design, cutter size, and usable diamond volume. Hard stringers require high stability in order to maintain bit life by preventing premature component failure. Technologies developed are conventional antiwhirl theory, localized cutter placement to extend bit life, and an innovative low-friction gauge pad that spans two blades and encloses a junkslot.
The case history demonstrates the significant performance improvement that can be achieved through interbedded formations by combining innovative PDC bit technologies. The study examines the development of the 1214-in. section in the Tunu field, Indonesia. The continual development of the project is discussed including a lighter set variant to complete the same application and the successful translation of the design philosophy into a slimhole program.
Coiled-Tubing Drilling of Horizontal Sidetrack in House Mountain Field, Alberta
Authors: Milligan M. R. , Andreychuk M. T. , Lunan W. B. 
Published: December 2007

Summary
In 1995, the first horizontal sidetrack successfully drilled using coiled tubing (CT) was carried out at Shell's House Mountain oilfield. The objective was to drill underbalanced a 378-in. diam by 300-m-long horizontal hole section from an existing vertical, cased oil well. The existing well was re-entered using a conventional drilling rig; a window milled in the casing, and the build section drilled to an inclination of 90°. 238-in. CT was then used to directionally drill the horizontal section underbalanced with nitrified water. The zone of interest was a Devonian-age reef-edge and limestone structure, at a depth of about 2200 m, called the Slave Point.
A case history of directionally drilling the horizontal sidetrack using 238-in. OD. CT is provided. Coiled-tubing drilling proved to be a cost-effective alternative to drilling the horizontal sidetrack without using a conventional drilling rig. Shorter trip times, underbalanced drilling, enhanced rates of penetration (ROP), and the ability to maintain weight on bit were all achieved. ROPs increased by up to three-fold while drilling underbalanced.
Shear Effects on Polyacrylamide/Chromium (III) Acetate Gelation
Authors: Broseta Daniel , Marquer Olivier , Zaitoun Alain , Baylocq Pascal , Fery Jean-Jacques 
Published: December 2007

SummaryIn practice, gel formulations used in water shutoff and conformance improvement treatments are subjected to hours of strong shearing in surface and well equipment (i.e., pumps, tubings, etc.) and in the near-wellbore part of the formation before being left under quiescent conditions (well shut-in). The purpose of rheological measurements presented in this paper is to assess the influence on polyacrylamide/chromium (III) gelation of shearing sequences representative of those occurring in the field. The gel properties investigated are the gelation time and final yield stress, which are related, respectively, to the pumping time and to the maximum differential pressure the gel can withstand in the reservoir (matrix or fracture).Two different polyacrylamide/chromium (III) formulations were analyzed, one of which, involving a high-molecular-weight polyacrylamide, is adapted for plugging fractures, and the other one, involving a low-molecular-weight polyacrylamide, is usually employed for plugging porous matrices. These formulations had previously been used in some specific field applications. The experiments consisted of a series of viscosity, storage modulus and yield stress measurements on the gelling solutions, with the purpose of quantitatively characterizing the gelation kinetics and final strength of the gel formed.The results demonstrate that the effect of shearing is to restrain gelation and, in particular, to limit the viscosity rise due to the formation of aggregates of crosslinked polymers (microgels). The gelation time, defined in relation to this viscosity rise, increases with shear rate for the high-molecular-weight (non-Newtonian) formulation, but is unaffected by shear for the low-molecular-weight (Newtonian) formulation. Experiments have also been conducted in which an extended initial period of strong shearing was followed by another extended period of rest. The final gel strength of both formulations, evaluated from yield stress measurements, turned out to be independent of the shear rate history.
Application of Lévy Random Fractal Simulation Techniques in Modeling Reservoir Mechanisms in the Kuparuk River Field, North Slope, Alaska
Authors: Gaynor G. C. , Chang E. Y. , Painter S. L. , Paterson Lincoln 
Published: December 2007

SummaryIncorporating a suitable level of heterogeneity into reservoir simulations is necessary for accurate prediction of production rates and final recoveries. Spatial correlation of petrophysical properties, particularly permeability extrema, exerts a profound influence on flow underlying reservoir displacement and depletion processes. Common modeling techniques are founded on Gaussian assumptions for statistical distributions. Such Gaussian-based approaches can inadequately model the permeability extrema that can dominate reservoir performance. However, optimal reservoir management strategies at the Kuparuk River Field require that significant efforts be made to correctly model reservoir behavior.This study utilizes a new method, Lévy fractal simulation, for interpolating permeability at a former gas injection area now being targeted for oil production. The main producing interval is a diagenetically and mineralogically complex clastic unit. The diagenetic complexity causes difficulties in the lateral modeling of large changes in petrophysical properties observed in near-vertical wells, particularly permeability. Prior efforts at modeling the movement of gas, at typical interwell scales, have met with limited success. In this study, the Lévy technique employs automatic calibration with log and core data for the interwell interpolation of the spatially complex reservoir properties. The Lévy fractal simulations preserve the sharp jumps in reservoir properties observed at stratigraphic boundaries and within reservoir subzones. The spatially correlated petrophysical properties are consistent with geologic experience.A fine-scale permeability model incorporating well conditioning data was built using the Lévy fractal interpolation technique. This model encompassed not only the gas injection area but drillsite patterns immediately adjacent. The model preserves the geometry of the reservoir units so that truncation and onlap relationships are preserved. The permeability extrema in the model are characterized by lateral continuities extending over many grid-blocks away from control locations. Porosity was modeled using sequential Gaussian simulation in which well porosity logs were used as the primary conditioning data, and the modeled permeability used as secondary conditioning data. The fine-scale model was then used as input in an upscaled dynamic simulator built to test reservoir mechanisms. The model was also useful for prognosing porosity and permeability at proposed well locations. Early drilling results indicate that substantial quantities of producible oil remain in the former gas injection area.
Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2
Authors: Farshad F. F. , Garber J. D. , Polaki Venugopal 
Published: December 2007

Summary
A WINDOWS-based computer model has been developed which can help predict the location of corrosion and the life of a carbon steel tubular in a gas condensate well containing carbon dioxide. This model provides a physical description for the five different flow regimes that can occur in gas wells. This description has proven to be useful in the prediction of the corrosion rates of these wells. The model does not use the partial pressure of CO2 in the calculation of corrosion rate. It has been found that the hydrodynamics is the most important parameter in this type of corrosion. The model has an expert system associated with it which takes into account the volume fraction of condensate and water in the tubing. When the water level reaches and exceeds 50% of the total volume, the tubing is completely water-wet and the corrosion rate is a maximum. At the point where 30% or less of the volume of the fluid is water, the corrosion rate is believed to be zero. Caliper surveys have played a role in our ability to establish these points of transition within the model. Case histories have been presented which illustrate how the model can help in performing failure analysis and design of gas condensate wells.
Laboratory Modeling of Mudcake Application and Erosion for Gravel-Pack Design in Horizontal Wells
Authors: Becker T. E. , Gardiner N. H. 
Published: December 2007

Summary
Successful gravel packing of long horizontal sections depends in part on preventing carrier fluid from leaking off to the surrounding permeable reservoir. This requires correctly designed drill-in fluids to apply a thin filter cake, rendering impermeable the sand formation at the wellbore wall. Filter cake must be embedded sufficiently within the formation interstitial space to resist scouring by flowing sand during the gravel-packing operation. This paper summarizes testing using a large-scale laboratory apparatus and procedure designed to test the effectiveness of drill-in fluids planned for use in horizontal wells recently drilled in the Gulf of Mexico.
This paper shows the benefits of modeling a horizontal gravel-pack interval before attempting to install the gravel pack. Gravel-packing techniques for long horizontal well sections were evaluated with a laboratory model of a casing/borehole annulus. In the horizontal section modeled, permeability is sufficient to interfere with the transportation and distribution of pack sand from total depth to dogleg when positive differential pressure is maintained. The goal of this modeling experiment was to predict whether the formation's permeability at the sandface could be reduced enough to allow successful gravel packing without damaging the formation far beyond the sandface.
Gravel-packing technology is well established for near-vertical wells, with off-the-shelf equipment and textbook procedures readily available. The exceptionally long producing intervals in horizontal wells present a greater challenge for gravel packing, however, interval permeability is, by design, continuous. This continuous permeability both enhances well productivity and allows increased wellbore fluid flow into reservoir rock. When the permeable formation absorbs the fluid energy necessary to evenly disperse pack sand throughout the section, sand bridging can result, restricting the flow before the pack sand is fully distributed across the entire interval.
The laboratory model simulates the axial flow of drilling and/or completion fluids through an annulus. The model has an impermeable confining wall (simulating the casing) and a permeable wall (simulating reservoir rock). Recently, it was used for testing the capacity of a drill-in fluid to reduce reservoir near-face permeability, and allow sand propagation throughout a long horizontal interval. Results obtained both in the laboratory and in subsequent field trials validate the use of a drill-in fluid in reducing near-sandface permeability. The procedure has been used successfully on multiple horizontal wells with typical horizontal section lengths of 1,000 to 2,500 ft. Plans are underway to continue the practice in additional wells.
Evaluation of Selective vs. Point-Source Perforating for Hydraulic Fracturing
Authors: Underwood P. J. , Kerley L. A. 
Published: December 2007

Summary
"Select-fire" (SF) and "point-source" (PS) perforating completions were used to fracture the Reef Ridge diatomite formation in the Midway-Sunset field, Kern county, California. Fracturing treatment analysis and production history matching were used to evaluate the reservoir and fracturing parameters for both completion types. Single fractures were created with the PS completions, and multiple fractures resulted from many of the SF completions.
Descriptions of the reservoir, production history, and fracturing techniques used leading up to this study are presented. Fracturing treatment analysis and production history matching were used to evaluate the reservoir and fracturing parameters for both completion types.
The work showed that single fractures were created with the PS completions, and multiple fractures resulted from many of the SF completions. A good correlation was developed between productivity and the product of formation permeability, net fracture height, bottomhole pressure, and propped fracture length. Results supported the continued development of 10 wells using the PS concept with a more efficient treatment design, resulting in substantial cost savings.
New Treatment for Removal of Mud-Polymer Damage in Multilateral Wells Drilled Using Starch-Based Fluids
Authors: O'Driscoll K. P. , Amin N. M. , Tantawi I. Y. 
Published: December 2007

SummarySignificant improvement in production from horizontal, multilateral wells has been realized through the application of specific enzyme breaker (SEB) technology for the removal of natural starch polymers used in drilling operations. This new treatment allows placement of a fluid to remove polymeric mud damage at the cessation of drilling operations for each multilateral section, which could not otherwise be re-entered for cleanup and effective stimulation during completion of the well.
Estimation of Gross Rock Volume of Filled Geological Structures With Uncertainty Measures
Authors: Abrahamsen Petter , Hauge Ragnar , Heggland Knut , Mostad Petter 
Published: December 2007

Summary
The gross rock volume of a filled structure is uncertain because of uncertainty in the determination of caprock depth and the uncertainty in depth to the hydrocarbon contact determined by the spill point of the caprock. Ignoring this uncertainty might lead to biased volume estimates. This paper reports two procedures to assist with assessing this uncertainty to obtain better estimates. The first is to use conditional simulation techniques to generate realizations of the depth to the caprock. The second procedure is a new fast algorithm that determines the location of the spill point and trapped area of each caprock realization. Taken together, the two procedures determine the thickness and lateral extension of each reservoir realization. Finally, gross rock volume for each realization can be calculated and the volumetric uncertainty can be quantified in terms of expectation, histograms, percentiles, etc., for the whole set of realizations. A synthetic example and an example from the North Sea illustrate the use of these procedures. A method for including knowledge of the spill-point depth for improving depth maps is also presented.