bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geologic Hazards Related to Offshore Drilling and Construction in the Orinoco River Delta of Venezuela
Authors: Butenko J. , Barbot J.P. 
Published: December 2007

This paper describes the results of a seabed and shallow stratigraphy reconaissance survey conducted offshore the Orinoco River delta in Venezuela. Several geologic features were encountered that may be hazardous to offshore drilling and construction.

Introduction
Since Dec. 1977, the Centro de Investigacion y Desarrollo (INTEVEP S.A.) of Petroleos de Venezuela S.A. (PDVSA) has been conducting a general geotechnical investigation in the Orinoco River delta region in cooperation with McClelland Engineers Inc.To assess the safety of oil drilling operations, this study has been carried out with these main objectives:define the basic geotechnical and geologic characters of the surficial sediments,identify the potential geologic hazards for drilling and future oil production, andgain an understanding of the sedimentary process and the recent geologic history of the area.
A high-resolution geophysical survey and a sampling program were conducted in the investigation area offshore the Orinoco River delta. A wide range of geotechnical, geologic, and chemical analyses were performed on the samples. As a base for the general understanding of the area of interest, a broad geologic study with emphasis on tectonics was carried out on a regional scale.

Methods of Study
The explored area covers 12,500 km of the continental shelf and the continental slope offshore the Orinoco River delta. The maximum water depth is 600 m, which is reached only in the northeastern part of the investigated area. Ninety percent of the geophysical lines were run in water depths between 10 and 200 m, the lowest limit corresponding to the limitations of the survey vessel (Fig. 1). Almost no investigation had been carried out before -in this region, and only limited data could help to define the geophysical grid. For this reason, it was decided to begin with a broad reconnaissance phase over a 10 × 10 km grid. These profiles provided general information that was used to define the most interesting areas that should be covered by a 5 × 5 km grid. Then, according to the data obtained, two main areas of high geologic complexity that seemed to be most hazardous to petroleum exploration were identified and surveyed with a 2.5 × 2.5 km grid.Accurate positioning was assured using an Argo DM 54(TM) range-range phase comparison system, with three fixed shore stations and a mobil station aboard the vessel. Generally, the accuracy of the system can be considered in the order of 10 m. Signal instability and loss of signals sometimes occurred at night, but only at great distances from the shore stations. Coarse checks were made periodically with a satellite system.
JPT
P. 764
Geology and Geotechnical Features of the Mid-Atlantic Continental Shelf
Authors: Demars K.R. , Charles R.D. , Richter J.A. 
Published: December 2007

This paper summarizes and augments the existing geological and geotechnical engineering data on the U.S. mid-Atlantic continental shelf. This study provides a basis for planning and management for shelf users and for delineating research needs.

Introduction
Several major construction efforts are anticipated on the U.S. mid-Atlantic continental shelf over the next decade, including oil platforms and pipelines, deepwater ports, and power plants. In addition, there are many ongoing activities on the continental shelf, such as recreation, waste disposal, fishing, public safety, and defense. In each of these proposed efforts or ongoing activities, there is an interaction with the seabed of localized or regional nature. Preliminary information on the regional geology and sediment properties is needed for proper planning and management by shelf users and for delineating research needs. In fact, the National Research Council (NRC) Committee on Seafloor Engineering has acknowledged marine sediment studies to be of the highest priority for continental shelf development. Particular needs exist for soil maps and fundamental knowledge of the physical and engineering properties of marine sediments.The overall objectives are to summarize and improve existing geological and engineering shelf sediment information. Since the location of potential seabed developments are flexible, this study covers the general area off Delaware and extends from the beach to the shelf break. The primary objectives are (1) to assemble and interpret available geological and geotechnical data in view of possible engineering developments and (2) to obtain supplementary property data from laboratory tests. The laboratory tests were performed on samples acquired by the USGS during the recent continental margin boring program. It is the intent of this study to examine the general distribution of sediments and the unique aspects of engineering behavior. A brief review of the geology will provide a basis for examining the sediment property variations in addition to defining anticipated shelf development and construction hazards.

Delaware Continental Shelf
The continental shelf off Delaware is typical of the shelf along eastern North America. From a bathymetric map (Fig. 1) the shelf may be described as being broad and flat with a width of about 200 km (125 miles). The average slope is only 0.05 degrees, but many morphological features of the intermediate size, such as shoals or sand waves, exhibit locally steeper slopes of 2 or 3 degrees or more. In fact, very little of the outer-shelf topography reflects the morphology of coastal elements. The Hudson Channel and Canyon to the north of the Baltimore Canyon trough area is the only major feature that cuts the continental shelf and slope.
JPT
P. 363＾
Crushing of Calcareous Sands During Drained Shear
Authors: Datta M. , Gulhati S. K. , Rao G. V. 
Published: December 2007

Abstract
Sands are known to crush under stresses at high confinement. Particle crushing is more predominant under shear stresses than under isotropic compression. Stresses in soil under deep foundations often reach the range where crushing becomes significant. Calcareous sands crush more readily than terrigenous quartzitic sands. Calcareous sands occur as skeletal remains of marine organisms and/or as nonskeletal oolites of calcareous material. Skeletal calcareous sand grains are characterized by the presence of intraparticle voids that increase the tendency of these sands to crush under stress. Presence of thin plate-like shell fragments further increases the crushability of calcareous sands.
Deposits of calcareous sands are encountered extensively on the continental shelves lying between latitudes 30°N and 30°S. In many such marine areas, jacket-type offshore structures for oil production are being founded on calcareous sand strata – e.g., in the Arabian Sea offshore India, in the Bass Strait offshore Australia, and in the Persian Gulf offshore Saudi Arabia. The foundations of these structures consist of deep-penetration piles. These piles derive their axial load capacity from the skin friction resistance and the end bearing resistance offered by the soil strata they penetrate. Static pile load tests in calcareous sand strata have exhibited unusually low values of unit skin friction and unit end bearing capacity.1,2 It is believed that particle crushing that occurs during pile driving and static loading is one of the causes for the low pile capacity.2,3 For design of deep-penetration piles in calcareous sand strata, low values of limiting unit skin friction and limiting unit end bearing capacity currently are adopted in comparison to those being used for terrigenous quartzitic sands.3 To arrive at a rational design practice for piles in calcareous sands, one must begin by (1) identifying a method for quantitatively expressing the the sands' propensity to crush, (2) determining the extent of crushing of different types of calcareous sands in comparison to terrigenous sands, and (3) isolating the influence of crushing on shear behavior, which partly controls the end bearing and skin friction offered by such sands.
This paper describes the results of an experimental investigation designed to achieve these three objectives and, in part, offers an explanation for the low skin friction and end bearing values in field tests.
Beyond Heat Checking: Frictional Heating Causes Drillpipe Failure in an Extended-Reach Well
Authors: Vernon R. J. , Wade E. H. R. 
Published: December 2007

Summary
Failure of a 5-in. proprietary hole-cleaning drillpipe joint occurred during platform drilling of a North Sea extended-reach well. The joint was run in heavyweight drillpipe above the bottomhole assembly (BHA). Its failure resulted in the loss of the BHA, including high-value rotary-steerable tools, at 23,250 ft measured depth (MD). The failure occurred when the string was being rotated out through a tight spot. Topdrive stallouts and intermittent circulation were experienced. The maximum overpull applied was 50,000 lbf. The appearance of the recovered pipe indicated ductile failure, despite a zone of abnormally high hardness adjacent to the fracture.
Investigation established that local frictional heating had heated the drillpipe above 1,441°F and that ductile failure had occurred when hot, although the string had not been overloaded in tension or torsion. After the rupture, the mud-flow quench hardened the hot pipe to above 572 Vickers of 10kg load Hardness (HV10) [approximately 54 Rockwell Hardness on a C scale (HRC)—Note: hardness values are given "as measured"; conversions are approximate and for information only].
"Heat checking" (i.e., downhole surface hardening of frictionally heated drillpipe) is an established phenomenon that is described in the literature. The case reported herein represents an extreme consequence of frictional heating that has important implications for the management of topdrive drilling operations.
Three-Phase Hydraulic Conductances in Angular Capillaries
Authors: Al-Futaisi Ahmed , Patzek Tad W. 
Published: December 2007

SummaryIn this paper, we extend to three fluid phases a prior finite-element study of hydraulic conductance of two-phase creeping flow in angular capillaries. Previously, we obtained analytic expressions for the hydraulic conductance of water in corner filaments. Here, we present the results of a large numerical study with a highresolution finite-element method that solves the three-phase creeping flow approximation of the Navier-Stokes equation. Using the projection-pursuit regression approach, we provide simple analytic expressions for the hydraulic conductance of an intermediate layer of oil sandwiched between water in the corners of the capillary and gas in the center. Our correlations are derived for the oil layers bounded by the concave or convex interfaces that are rigid or allow perfect slip. Therefore, our correlations are applicable to drainage, spontaneous imbibition, and forced imbibition with maximum feasible hysteresis of each contact angle, oil/water (O/W), and gas/oil (G/O). These correlations should be useful in pore-network calculations of three-phase relative permeabilities of spreading oils. Finally, we compare our results with the existing correlations by Zhou et al.18 and Hui and Blunt,19 who assumed thin-film flow with an effective film thickness proportional to the ratio of the flow area to the length of the no-flow boundary. On average, our correlations are two to four times closer to the numerical results than the corresponding correlations by Zhou et al. and Hui and Blunt.
Severe Slugging Attenuation for Deepwater Multiphase Pipeline and Riser Systems
Authors: Tengesdal J. Ø. , Sarica Cem , Thompson Leslie 
Published: December 2007

Summary
Exploitation of offshore petroleum reservoirs has recently moved to ever-increasing water depths. Production from fields in water deeper than 1800 m is now a reality. The use of long deepwater risers that conduct production from multiple wellheads on the sea-floor to the surface predisposes the system to severe slugging in the riser for a wide range of flow rates and seabed topography. When one considers the length of the deepwater risers, the problem is expected to be more severe than in production systems installed in shallower waters. Severe slugging could occur at high pressure, with the magnitude of the pressure fluctuations so large as to cause a shorter natural flow period with subsequent consequences, such as premature field abandonment, loss of recoverable reserves, and earlier-than-planned deployment of boosting devices.
In this study, a novel idea to lessen or eliminate severe slugging in pipeline/riser systems has been thoroughly investigated. This idea was first proposed by Barbuto1 and later developed independently by Sarica and Tengesdal.2 The principle of the technique is to transfer pipeline gas to the riser at a point above the riser base. The transfer process will reduce both the hydrostatic head in the riser and the pressure in the pipeline, consequently lessening or eliminating severe slugging by maintaining steady-state two-phase flow in the riser.
An experimental study has been conducted with a 7.62-cminside-diameter (ID) riser (14.63 m high) and pipeline (19.81 m long) system. A broad range of data was collected from the facility in both the severe slugging and stable regions. It was found that the severe slugging models currently available do not predict the region accurately for larger-diameter pipes. Data acquired with the external gas bypass have proved the proposed elimination technique.
Gas-Phase Viscosity of Hydrocarbon Mixtures
Authors: Lee A.L. , Eakin B.E. 
Published: December 2007

Abstract
Atmospheric pressure viscosity values for light hydrocarbons were calculated by a simple mixing rule based on the Sutherland constants for pure components. This method was further extended so that the atmospheric pressure viscosity of a mixture may be calculated based on the molecular weight information only.
Introduction
A proven method for estimating the gas-phase viscosity of a mixture is the one by Herning and Zipperer. This mixing rule has the following form:
(1)
One method for calculating the pure component viscosity mu is the Sutherland equation, which has the following form:
(2)
The Sutherland constants B and S are determined from experimental data. A set of Sutherland constants for light hydrocarbons based on the data of several investigators is presented in Table 1.
APPLICATION
The Herning-Zipperer equation and the Sutherland equation were used to obtain an equation for calculating the gas-phase viscosity of light hydrocarbons. This equation has the form,
(3)
where,
(4)
and
(5)
Eq. 3 was used successfully in the study of methane-n-butane mixtures. Further analysis indicated that the Sutherland constants are a function of molecular weight. The gas-phase viscosity may be calculated based on molecular weight information only. The following equation was developed:
(6)
The atmospheric pressure viscosity of ethane, propane, n-butaneandfourmethane-propanemixtwes calculated on the basis of Eq. 6 are compared with the data of other investigators in Tables 2, 3, 4 and 5, respectively. A plot of atmospheric pressure viscosity vs molecular weight based on Eq. 6 is presented in Fig. 1.
SPEJ
P. 247ˆ
Reservoir Modeling for Horizontal-Well Exploitation of a Giant Heavy-Oil Field
Authors: Tankersley T. H. , Waite M. W. 
Published: December 2007

Summary
The Hamaca field, located in Venezuela's Orinoco heavy-oil belt, is a giant extra heavy-oil accumulation operated by Ameriven, an operating agent company for PDVSA, ConocoPhillips, and ChevronTexaco. Over the 35-year life of the field, more than 1,000 horizontal laterals are planned to deliver 190,000 BOPD to a heavy-oil upgrader facility. Reservoir models are built to support a broad continuum of activities to meet this objective. This paper will review the Hamaca reservoir-modeling process, the challenge of integrating many sources of geologic and geophysical constraints (including horizontal-well information), the focus on continuous model improvement, and issues unique to Hamaca rock and fluid properties. We will show that efficiently evolving a very large geocellular model in an active project like Hamaca can be accomplished through the use of object-oriented process automation. In addition, the paper will illustrate that careful consideration should be paid to issues related to horizontal-well sampling bias and positional uncertainty before constraining a geocellular model with horizontal-well data. The paper will discuss the multiple sophisticated modeling techniques that were used to address the objectives of the Hamaca modeling program.
Development of the Alba Field-Evolution of Completion Practices, Part 1: Openhole Screen-Only Completions to Gravel Pack
Authors: Murray G. , Brookley J. , Ali S. , Davidson E. , McMillan N. , Roberts J. 
Published: December 2007

Summary
The Alba reservoir (located in the central North Sea) is a highly permeable, unconsolidated sand body with lenses of reactive shales within the reservoir sand. From the initial decision to exploit the field with horizontal wells, there has been an evolutionary approach to selecting the most appropriate drilling fluid and completion technique. Field development has been marked by a drive to increase productivity and reduce the total cost of the ownership of the asset.
The major challenges in completing wells in this field involve sand control and inhibition of reactive reservoir shales.
Initially, completions were prepacked screens in open hole, and the fluid used to drill the reservoir section was oil-based mud (OBM). Productivity was lower than expected, but improvements were achieved by switching to sized salt water-based mud (WBM) and initiating a very stringent quality-control procedure for the drilling and completion fluids. However, screen failure occurred within 2 to 3 years of production startup, and the wells almost invariably sanded up. More recent changes have involved a switch to sized calcium carbonate WBM and openhole gravel packs.
Because the geology of the Alba field dictates that there is almost always some shale exposed in the openhole reservoir section, it was found that the gravel-carrier fluid needs to be equally as inhibitive as the drill-in fluid.
Since 1998, 13 openhole gravel packs have been successfully completed, with high flow rates and no history of sand production in all cases.
This paper deals with the performance of the various techiques applied and details the best practices derived for optimum productivity and screen longevity.
The Mathematical Model of Nonequilibrium Effects in Water-Oil Displacement
Authors: Barenblatt G. I. , Patzek T. W. , Silin D. B. 
Published: December 2007

Summary
Forced oil-water displacement and spontaneous countercurrent imbibition are the crucial mechanisms of secondary oil recovery. Classical mathematical models of both these unsteady flows are based on the fundamental assumption of local phase equilibrium. Thus, the water and oil flows are assumed to be locally distributed over their flow paths similarly to steady flows. This assumption allows one to further assume that the relative phase permeabilities and the capillary pressure are universal functions of the local water saturation, which can be obtained from steady-state flow experiments. The last assumption leads to a mathematical model consisting of a closed system of equations for fluid flow properties (velocity, pressure) and water saturation. This model is currently used as a basis for numerical predictions of water-oil displacement.
However, at the water front in the water-oil displacement, as well as in capillary imbibition, the characteristic times of both processes are, in general, comparable with the times of redistribution of flow paths between oil and water. Therefore, the nonequilibrium effects should be taken into account. We present here a refined and extended mathematical model for the nonequilibrium two-phase (e.g., water-oil) flows. The basic problem formulation, as well as the more specific equations, are given, and the results of comparison with an experiment are presented and discussed.
Smackover Nacatoch Crude Oil – Separation of Surfactant Precursors and Their Effect on the Crude
Authors: Runnels J. H. , Engel C. J. 
Published: December 2007

Abstract
A procedure is given for separating surfactant precursors that occur in some crude oils. The effect of the precursors on the properties of the oils are described also. The separations were made by silica gel chromatography on crude oil from which the asphaltenes had been removed. The effect of the precursors on the properties of the crude was evaluated by blending the surfactant precursors into the original oil, a modified oil, or a hydrocarbon solvent such as benzene.
Precursors activated and converted to surface active materials by a strong base such as sodium hydroxide are effective in reducing the interfacial tension between the oil and aqueous phase. Occurrence of precursors in crude oils is essential for improved oil recovery by the causticflood process. The procedure for separating the precursors should provide a viable means for evaluating the applicability of a causticflood tertiary oil recovery process to a particular crude or reservoir.
History Matching of Three-Phase Flow Production Data
Authors: Li Ruijian , Reynolds A. C. , Oliver D. S. 
Published: December 2007

Summary
Adjoint equations for 3D, three-phase flow problems are developed and implemented to calculate the sensitivity of production data to permeability fields and well skin factors. Typically, the development of adjoint equations is rather tedious, but the formulation given here makes the development and numerical solution of adjoint equations straightforward. The procedure for calculating sensitivity coefficients is coupled with a fully implicit finite-difference simulator to develop an automatic history-matching procedure. Even if one does not wish to fully automate history matching, sensitivity coefficients are useful for understanding the physics that control 3D multiphase flow and the influence of local reservoir properties on production data. Procedures to estimate the value of particular types of data [pressure, producing gas/oil ratio (GOR), and water/oil ratio (WOR)] for reducing the uncertainty in estimates of reservoir properties are applied and discussed.
Coupled Geomechanics and Reservoir Simulation
Authors: Thomas L. K. , Chin L. Y. , Pierson R. G. , Sylte J. E. 
Published: December 2007

SummaryAn iterative procedure is presented in this paper to couple geomechanics and reservoir simulation models for the simulation of weaker rock formations with complex constitutive behavior. Parallel computing is employed in the coupled model to reduce run time in the compute intensive geomechanics model. The procedures developed here are general, and can be applied to any reservoir simulation and geomechanics model.Field and example problems under a variety of exploitation scenarios are presented to demonstrate the utility and robust nature of the coupled model. For example, a large-scale field case was simulated using the coupled model with 16 processors for the geomechanics model. The total CPU time for a 30-year simulation run was approximately 2 hours. These results indicate that it is both economical and practical to use the proposed procedure and parallel computing for analyzing field-scale problems that integrate reservoir and geomechanics simulation.