bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of Multistring Casing Design with Wellhead Growth
Authors: Samuel G. Robello , Gonzales Adolfo 
Published: December 2007

Abstract
The casing program of a well represents a significant portion of the total well cost. An approach is required to reduce the tubular cost without sacrificing the safety and integrity of the well. This paper presents a study on the optimization of multistring casing design with complex load conditions, annuli fluid expansion and wellhead growth. Casings for different drilling phases are selected in such away that minimum cost casing design is achieved. The optimization is carried out with the objective function of minimum cost and with the multiple constraints of strength of the casing, drift diameter, casing section length, number of sections, wellhead growth and number of available pipes in the inventory.
Interval branch and bound optimization technique is used to find global minima of the cost function. This optimization not only results in calculating minimum casing cost design efficiently but also helps to take reliable decisions especially for offshore wells. The heuristic technique used to search the conformational minimum cost design space with the branch and bound approach gives added structural insights of casing design. Furthermore, this addresses the adverse impact of the annulus fluid expansion and wellhead growth on the efficiency of optimization. This also presents an approach whereby the initial single string negative impact design used to find a solution that maximizes well integrity are eliminated.
The optimization method proved to be cost effective wherever the annuli fluid expansion-wellhead growth is a concern. Such effectiveness will depend on the complexity of the annuli fluid expansion-wellhead growth problem. For wells where the annuli fluid expansion is not a problem may result in a higher cost casing design than expected compared to the wells where the wellhead growth and annuli fluid expansion are critical. The cost optimization will depend on the amount of wellhead movement allowed.
A new concept of Wellhead Growth Index (WHI) is introduced. WHI encapsulating the annuli fluid expansion and wellhead growth provides a simple practical way to view the severity of the wellhead movement during the course of drilling and as well as the production phase of the well. The practical usefulness of the theory, backed by the fundamental and optimal analysis, is demonstrated with two numerical examples.
Case History of the World's First Level 5 Multilateral Completed from a Semisubmersible Rig
Authors: Pasicznyk A. M. , Hogg W. C. , Williams D. L. , Cordeiro C. M. P. , Sotomayor G. P. G. , Alves I. , De Oliveira R. L. L. , Blauth M. 
Published: December 2007

Abstract
Multilateral technology has become a catalyst for enabling deepwater development. This challenging environment dictates that functionality and junction integrity are key requirements for multilateral completions. For an injection well in the Voador Field, offshore Brazil, a TAML Level 5 multilateral completion was implemented from a semisubmersible rig to achieve the junction isolation required for this application. It is the intent of this paper to demonstrate that a complex TAML Level 5 multilateral completion can be professionally designed, managed, and implemented from a semisubmersible rig, while saving ten million dollars (US) in costs over conventional technology applied in this region. This will be accomplished by reviewing the operator's deepwater development philosophy, reservoir considerations, design, operational procedures, and overall cost information related to the completion. In addition, details of the challenges faced, problems solved, and lessons learned will be examined on the world's first TAML Level 5 multilateral well completed from a semisubmersible rig, the Petrobras 8-VD #6HP-RJS and #7HPA-RJS dual lateral injection well in the Campos Basin off the coast of Brazil.
Log Ascii Standard (LAS) Version 3.0
Authors: Heslop Kenneth , Karst James , Schmitt Dennis , Prensky Stephen 
Published: December 2007

Abstract
An updated version of LAS (Log Ascii Standard) is presented. The purpose of this version is to provide a consistent standard that can accommodate all types of digital log data and non-log borehole data, providing a more robust standard for data exchange and storage, and to increase the applicability of LAS files.
Input from industry is requested to ensure that the final specifications meet the needs of users and data managers. We anticipate that the final specifications will achieve wide acceptance, as were the previous versions.
Introduction of a New Through-Tubing Multifunction Pulsed Neutron Instrument
Authors: Gilchrist W. A. , Prati E. , Pemper R. , Mickael M. W. , Trcka D. 
Published: December 2007

Abstract
We are introducing a new 1-11/16-inch multi-function pulsed neutron instrument. The Reservoir Performance Monitor (RPM) has operating modes allowing pulsed neutron decay, pulsed neutron spectrometry, pulsed neutron holdup, neutron activation water flow, and radioisotope measurements. The tool is combinable with fluid density, spinner flowmeter, or more advanced production logging instruments.
The new instrument includes three gamma-ray detectors arrayed above a new neutron generator that can be pulsed at different frequencies and modes for different types of measurements. The system employs short tool sections for ease in shipping and handling.
In the pulsed neutron capture mode, the tool pulses at 1 kHz, and records a complete time spectrum for each detector. An energy spectrum is also recorded for maintaining energy discrimination levels. Time spectra from short-spaced and long-spaced detectors can be processed individually to provide traditional thermal neutron capture cross section information, or the two spectra can be used together to automatically correct for borehole and diffusion effects and produce results that are very close to intrinsic formation values.
In the pulsed neutron spectrometry mode, the instrument pulses at 10 kHz, and records full inelastic and capture gamma ray energy spectra from each detector. These data are processed to determine critical elemental ratios including carbon/oxygen and calcium/silicon from the inelastic spectra and silicon/calcium from the capture spectra.
The pulsed neutron holdup imager mode yields both energy spectra and time decay spectra from each detector simultaneously. Measurements can be used to determine holdups of gas, oil, and water, and when combined with other production logs can provide a comprehensive production profile picture, even in deviated or horizontal wells.
The neutron activation mode provides water-flow measurements using one of several data acquisition methods. Stationary measurements are made in either of two modes, and measurements at different logging speeds can be used to segregate different flow rates in either an annulus or in an adjacent tubing string.
With the neutron generator turned off, the RPM can also be used to detect the distribution of materials, tagged with radioactive tracers, that are injected into the well during well treatments. In this manner, the effectiveness of operations such as hydraulic fracturing or gravel pack placement can be evaluated.
Winterized Paraffin Crystal Modifiers
Authors: Becker J. R. 
Published: December 2007

Abstract
Paraffin crystal modifiers have been used very successfully over the past several years in oil field applications where paraffin wax is a problem. Paraffin waxes cause tubing and flow-line problems for many crude oil production companies. One of the major drawbacks of the type of chemistry employed for the alteration of the paraffin waxes involves some of their undesirable physical properties. The nature of these chemicals requires that they interact with the growing crude oil waxes by co-crystallizing with the native paraffin waxes in the crude oil being treated. This requires that these products possess a relatively high melting point, or crystallization temperature. For this reason, these chemicals often freeze during the winter months in geographic areas having colder climates. The subject of the work presented in this paper deals with the winterization of these chemicals, and their altered physical behavior in cold climates. The products presented in this paper are presently under review by the U.S. Patent Office, and can only be referred to in a general sense. However, the results presented will demonstrate the increased utility of these improved products. More importantly, the advent of these winterized paraffin crystal modifiers promises a new era in paraffin wax control during critical times of the year (e.g., the winter months)
Generalization of API RP 14E for Erosive Service in Multiphase Production
Authors: McLaury B. S. , Shirazi S. A. 
Published: December 2007

Abstract
Solid particles such as sand in produced oil and gas can cause severe erosion damage even resulting in failure. Often production rates are limited or sand screens are used to limit the severity of erosion damage caused by the sand. However, even when applying these methods decisions such as determining the allowable (threshold) production rate or sand screen size must be made. The American Petroleum Institute Recommended Practice 14E (API RP 14E) is often used by oil and gas producers to calculate an erosional flowstream velocity. However, this guideline does not consider sand nor does it account for many of the factors that affect erosion. A model has been developed that account for factors such as geometry type, size, and material; fluid properties and rate; and sand size, shape, and density. Additionally, this method accounts for multiphase flow conditions. Comparison of the model with API RP 14E shows that API RP 14E is too conservative for high superficial liquid velocities but is not conservative enough for low superficial liquid velocities.
The Missing Scale: A Policy "U-Turn" is Necessary in its Management
Authors: Massonnat Gérard J. , Poujol Laurence , Rebelle Michel 
Published: December 2007

Abstract
Advances in geostatistics during the past ten years have led to fine-gridded reservoir models containing several millions of grid blocks. With steady increases in computer power, researchers have been able to reduce the effect of the upscaling phase on the erasement of heterogeneity in flow models.
However, cells in fine gridded reservoir models still represent thousands of cubic meters in which heterogeneity is usually ignored at that scale. This is called the Missing Scale.
Usually, scaling-up petrophysical properties from the scale of the plug to that of fine-gridded models is conducted either using simplistic methods between all scales, or by applying more sophisticated methods between plug and the laminae scale only.
The implicit assumption that rocks can be modeled as if they were homogeneous at the Missing Scale (between the lamina and the sedimentary body) leads to the neglect of significant effects on recovery due to capillary trapping or accentuation of bypass. This paper illustrates and quantifies problems induced by building overly simplistic models.
In an extensive study conducted on channel-type reservoirs, small-scale heterogeneity is input in models by way of anisotropic horizontal permeability. Waterflooding and primary depletion flow simulations are run using such models. Productions (recovery and production times) are compared with results from models run with isotropic permeability values. Various case studies are conducted to investigate the sensitivity of results to geology, relative permeabilities, mobility ratios, etc… They reveal the importance of taking into account the missing scale, with respect to a problem.
The Missing Scale can only be taken into account if the facies and sedimentary structures that are responsible for heterogeneity within sedimentary bodies are properly described.
A comprehensive study of the structures was conducted on a fluviatile environment. It yielded a classification of the structures with respect to the effects they should have on flow.
Finally, after evaluating the consequences of current modeling practices on flows, the different stochastic simulation techniques which could be potentially used in modeling small-scale heterogeneity are appraised. A pseudo-genetic modeling method is proposed for meandering channels.
An Inverse Channel Model for Flow and Transport in a Single Fracture
Authors: Jang Minchul , Kang Joe M. , Choe Jonggeun , Jang Il-Sik 
Published: December 2007

Abstract
Recent experimental and theoretical investigations of transport in a fracture indicate that fluid flows preferentially through flow channels in the fracture plane. Several one dimensional (1D) channel models have been introduced to interpret flow and transport through 2D fractured medium. However, those models couldn't reproduce a tracer breakthrough curve accurately and aperture distributions (i.e. aperture mean and standard deviation) could not characterize flow channels in the fracture.
In this paper, we present a new 1D channel model using an inverse algorithm. If a breakthrough curve is given, we divide its time into a limited number of intervals using the superposition theory, and then determine aperture distribution of each channel inversely. The new channel model reproduced the tracer breakthrough curve of a fracture almost exactly at any given pressure drop, and also matched the distributions of flow channels in the fracture. Using parameters analysis, we discovered that flow channeling becomes dominant in a fracture flow if the coefficient of variation is over 0.3. Therefore, the new channel model can simulate flow and tracer transport in a fracture effectively in that range.
We developed a 2D transport simulation model in a fracture and verified the model using experimental data. We used the model to compare the results of the 1D channel model with. Since we developed a 1D channel model to analyze 2D flow, it considerably reduces calculation time and computer memory.
High/Low Permeability Dual Tubingless Injector - A New Injector Completion Technique in Duri Steamflood, Sumatra, Indonesia
Authors: Bagis N. , Thurston F. K. , Kimber K. D. , Deemer A. R. 
Published: December 2007

Abstract
Current dual injector completion strategies in Duri Steamflood (DSF) allow separate steam injection into the Pertama and Kedua sands. The Pertama sand has about three to five layers and the Kedua sand has two or three. Each of the layers in the respective sands has contrasting rock properties where the permeability varies from 400 md to as high as 7000 md. Commingled steam injection into layers with large differences in permeability often creates a non-uniform steam distribution between the layers. This paper discusses the potential benefit of dual injectors based on splitting high and low permeability layers rather than upper and lower sands. This is achieved by cementing two tubing strings and utilizing oriented perforation technique. Simulation was used to investigate the difference in terms of oil recovery for the current dual injector completion technique, separate Pertama and Kedua sands, and the dual tubingless completion technique, separate high and low permeability layers. Four different cases were examined. Separation based on high and low permeability layers instead of Pertama and Kedua sand increase oil recovery by as much as 5%
Investigation and Application of Fracturing and Acidizing Technology to Improve UltraDeep Well Water Injectivity in DH Oil Field
Authors: Wang Zhenduo , Cui Mingyue , Wang Xiaoquan , Wang Xugang 
Published: December 2007

Abstract
With the extension of exploration and development of hydrocarbon into deeper formations, hydraulic fracturing and acidizing in these formations has become more and more important. Fracturing and acidizing ultra-deep wells added more difficulties to the optimization design and the safety of operation due to factors such as high formation temperature, high pumping pressure, high reaction rate between the formation rock and acid. These factors also affect the screening of chemicals and formulation of the working fluids. This paper discusses the investigation and practice of fracturing and acidizing technology in ultra-deep water injection wells (5830 to 5910 m in depth, 140·) in DH Oil Field emphasizing in: a) prediction of pumping pressure and measures to reduce it; b) optimization design and treatment implementation; c) field results of the application of the technology in production and water injection wells.
Significant stimulation results in production and injection wells were obtained with the applications of the fracturing and acidizing technology in DH oil field. The daily total water injection rate in five wells was only 672m3/d, a rate of 2200 m3/d was obtained after the first fracturing and acidizing treatments in 1995, 3500 m3/d after the second fracturing and acidizing treatments in 1997. The increase ratio of injectivity was 5.6. The average oil production rate per well stabled at about 217 t/d, the production decline rate was almost zero. The PFL rose from 1810 m to 1275 m.
Field practice shows that with a full understanding of the characteristics of the formation and requirements for the stimulation technology, difficulties associated with ultra-deep well fracturing and acidizing can be resolved and good stimulation results can be obtained.
An Evaluation of Water Reduction Treatments to Improve Vertical Lift Performance
Authors: Sabut Bangkong , Banu Nazrin , Davidson Colin J. 
Published: December 2007

Abstract
Baram Delta Operations (BDO) consists of a collection of nine producing oil fields located offshore Miri, Sarawak, Malaysia and operated by Petronas Carigali Sdn Bhd (Sarawak Operations). Production wells typically comprise dual strings with each string being completed with a single internal gravel pack straddling several producing intervals. In some strings high water production from a particular interval retards oil production from the other intervals by reducing vertical lift efficiency and in these cases water reduction technology was evaluated as a potential oil stimulation technique. Due to the completion configuration, PLT assessment could be of limited value and selective placement of plugging chemicals into target intervals was not considered a viable option. Thus despite the higher degree of uncertainty associated with the use of chemicals designed to selectively reduce water permeability (with little or no impact on oil permeability), these were considered the only viable option for potential application within BDO. Based upon independent confirmation of vendor submitted core flow test data, a linear, amphoteric polymer system was selected for field testing. The results of the core flow tests suggested that for intervals of high water saturation, treatment with the linear, amphoteric polymer system could reduce water permeability by about an order of magnitude while in intervals of high oil saturation, relative permeability to oil would be largely unaffected. Despite the highly encouraging laboratory results, an initial two well field test programme failed to prove the technology in the field. While the first field test failed due to operational difficulties, the second was a clear operational success but did not lead to reduced water production. Despite intensive post job analysis, the very wide discrepancy between the laboratory and field results has yet to be satisfactorily explained.
Application of a Multi-Purpose Compositional Simulator in Designing Steam Injection Projects
Authors: Cicek O. , Ertekin T. 
Published: December 2007

Abstract
In the design of an optimum enhanced oil recovery operation an accurate areal and vertical mapping and analysis of the simulation results plays a fundamental role. In this type of analysis not only should the finer details of the reservoir be considered, but also the grid system superimposed over the domain of interest should exhibit compatibility and consistency with the actual physics of the problem. This will help in accurate characterization of the reservoir and the ongoing physical processes within the domain of interest.
The implications of the aforementioned statements are investigated with the aid of developing a 3-D fieldscale steam injection simulator. The multi-phase mass and energy transport equations are based on compositional balances. In the model the gravitational and capillary forces are accounted together with the viscous flow phenomenon. A fully implicit treatment is used at the multi-block production and injection wells to couple the wellbore to the reservoir. A fully implicit technique is utilized in the solution of the nonlinear system of equations. The model is capable to solve (nhc+5) primary variables simultaneously where "nhc" represents the number of hydrocarbon components that can be considered.
A systematic analysis of the areal and vertical distribution of parameters such as pressure, temperature, phase saturations and composition is conducted. Through this detailed analysis the ever-changing relative effects of the various dominant forces on the establishment of production mechanisms and ultimately on the oil recovery are studied.
The fully implicit formulation, which assumes all the reservoir parameters and operational parameters to be functions of all primary variables identified, makes it possible to focus on any parameter and investigate its effects on oil production. Both qualitative and quantitative implications of capillary pressure on the oil production are observed to be strong functions of the size and uniform nature of the grid constructed over the computational domain.
The proposed model provides some significant insight into the displacement mechanisms and aids us in developing a comprehensive understanding of the nature and magnitude of the forces and controlling parameters. Such an understanding will help in the design of specifics of a recovery operation.
Stability of Junctures for Multilateral/Multibranched Wells
Authors: Fuentes J. A. , Economides M. J. , Carbonell R. S. 
Published: December 2007

Abstract
In creating complex well architecture a primary exercise is the initiation of a second branch from an existing "parent" or "mother" hole. The latter can be vertical, inclined or horizontal. The branch can be initiated at a range of angles depending on the drilling hardware used. In creating this angled branch from the main branch the stress concentration at the juncture depends greatly on the state of the far field stresses and their relative magnitudes and the mechanical properties of the rock. This work shows the calculation of the resulting state of stress at an open-hole juncture of two wells and along with a failure criterion delineates the stability of the new hole. The analysis is carried out for an angle of kick off of 2.5° and rock mechanical properties and far-field state of stress characteristic of a formation in Lake Maracaibo, Venezuela. Comparison of the estimated state of stress by the model and the rock failure criterion, predicts no mechanical instabilities at the juncture for this case. The analysis presented here demonstrates that it can be a useful tool for planning multilateral/multibranched wells by seeking formations that can withstand the stress imposed at the kick-off point and by orienting the initiation of the second branch in a direction that can ensure stability at the juncture.