bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of Density Derived from Pulsed Neutron Capture Measurements
Authors: Neuman C. H. , Sullivan M. J. , Belanger D. L.
Published: December 2007

Each service company that offers pulsed neutron logs includesmeasurements based on the gamma rays from inelasticscattering. The gamma rays that originate from the high-energy neutrons that undergo inelastic scattering necessarilyoriginate near the source. The number of these gamma raysthat reach detectors relatively far from the source reflects thegamma ray scattering by and thus the density of the materialbetween the scattered neutrons and the detector. Because thereare many factors other than density that influence the numberof gamma rays detected, service companies offermeasurements based on inelastic scattering as empirical tracesthat are used in combination with measurements based onneutron scattering. Such combinations are useful primarily torecognize gas and distinguish gas from low porosity. Onecompany offers a trace that represents density from the gammarays due to inelastic scattering, but the process of deriving thedensity involves the very empirical step of subtractingdifferent portions of the gamma rays attributed to factors otherthan inelastic scattering until a satisfactory approximation todensity is achieved.

This paper presents a method for predicting the gammarays from thermal neutrons to be subtracted from the totalgamma rays measured during the neutron pulse and acomparison of the density-like trace so derived with open-holedensity logs recorded in Cabinda, Angola, Africa.

The method presented for predicting gamma rays due tocapture is based on representing the decay of gamma rays afterthe neutron burst by two exponential decays. The fraction ofgamma rays due to thermal neutrons is different at differenttimes during the pulse, but the overall effect is predicted fromthe amplitudes and decay times that fit the data used torepresent sigma. While this removes variations in the fractionof capture gamma rays subtracted to create a density-like trace,the relationship between the amplitude of the trace and densityis still determined empirically.

The comparison with open-hole logs makes use of the factthat many of the logs run were run to distinguish brine from oilthrough casing. This enables comparison of the densitiesderived from cased-hole logs to those recorded from open-holelogs under conditions where the open-hole logs still representthe reservoir. Some of the log data studied were from intervalswhere gas saturations changed between the open- and cased-hole logs, and these afford a chance to compare changes indensity with changes in neutron porosities. Examplecomparison are presented and limitations discussed.
A New Technique for Carbon-Oxygen Logging Through Gravel Packs and Other Special Completions
Authors: Wanjau P. K. , Joseph J. , Ciammetti P. , Lassel K. , Akunna P.
Published: December 2007

Productive horizons in the Niger Delta basin of West Africa comprise clastic tertiary sequences that formed coastal barrier bars, beaches, tidal distributor channels and lagoonal deposits. Such reservoirs are often made up of very high permeability unconsolidated sands that require gravel-packed completions for efficient production. Water influx from edge- or bottom-aquifers is a dominant drive mechanism, and in this basin water salinity is often less than 30 kppm (i.e., predominantly fresh). It is no surprise that in this low-salinity environment carbon-oxygen (C/O) logging has become particularly popular for reservoir monitoring.

In the past, operators were often forced to exercise the high-cost option of pulling the completion string in order to run C/O logs. This was necessary because no logging tool was rated for saturation evaluation inside gravel-packs or other special completion elements such as blast joints. In this paper a new characterization for a slim C/O logging tool is presented that now extends its applicability to these special completion types. The technique is based on laboratory measurements made with the tool inside typical Niger Delta gravel-pack and formation lithology environments. These measurements were used to benchmark a Monte Carlo nuclear model from which a database was constructed. The questions of gravel-pack quality and of the pack's fluid content have been addressed in this work, as has the impact of uncertainties associated with these variables upon the final saturation answer.

The new characterization database has been used to evaluate C/O logs run in several wells in the Niger Delta. Three examples where the tool logged inside an internal gravel-pack (IGP) completion are presented in this paper. The examples demonstrate a significant improvement over a qualitative approach and provide for a more robust and reliable saturation computation.
Dynamic Multi-parameter Interpretation of Dual-Detector Carbon/Oxygen Measurements
Authors: Mickael Medhat , Trcka Darryl , Pemper Richard
Published: December 2007

Traditional C/O interpretation methods that rely on a limited set of data can not provide the fidelity and accuracy needed to interpret C/O data in complex completions, mixed lithology, or under variable holdup conditions. New interpretation methods based on computer modeling can now furnish accurate C/O response data, not only for applying sequential environmental corrections, but even for treating simultaneous variations in the logging conditions.

In this paper, we present new concepts of interpreting C/O data that fully utilize the power of computer modeling. The C/O response is dynamically generated at every depth level of the log based on a non-linear model that simultaneously accounts for variations in completion geometry, borehole diameter, formation porosity and mineralogy, and borehole holdup. The model also allows for normalizing the C/O response in a shale or a low-porosity zone.

A new treatment for dual-detector instruments is also presented that takes advantage of the precision and sensitivity of the two detectors rather than simply using one or the other. Data from the two detectors are combined in such a way that the error of the measured saturation is minimized, which should provide an optimum measurement under any condition.

Log examples are presented to show the degree of fidelity and accuracy of the new interpretation method. Examples are also shown that demonstrate the ability to normalize the C/O response in shale and low-porosity zones.
A Large Scale Geostatistical Study: the Bachaquero 2 Field
Authors: de Lestang A. Pelgrain , Cosentino L. , Lopez D. , Gonzalez J. E.
Published: December 2007

A geostatistical study has been performed in the framework of the Integrated Reservoir Study of the giant Bachaquero 2 oil field, located in the Maracaibo lake, Venezuela. The objective of the study was to take advantage of the exceptional well density (over 1300 wells) in order to build a detailed and robust 3D model for geological risk evaluation during drilling, as well as further reservoir modelling studies.

The geostatistical database has been built from the preliminary deterministic geological work (3D seismic interpretation, sequence stratigraphy, sedimentological and petrophysical analysis). Stochastic simulations have been run in terms of facies and petrophysical properties, using a pixel based, Truncated-Gaussian algorithm.

The stochastic model has been used in a variety of applications, from optimization of horizontal well trajectories, to infill drilling location and the construction of local scale numerical simulation models.
Electrofacies Characterization and Permeability Predictions in Carbonate Reservoirs: Role of Multivariate Analysis and Nonparametric Regression
Authors: Lee Sang Heon , Datta-Gupta Akhil
Published: December 2007

We propose a two-step approach to permeability prediction that utilizes non-parametric regression in conjunction with multivariate statistical analysis. First we classify the well log data into electrofacies types.This classification does not require any artificial subdivision of the data population but follows naturally based on the unique characteristics of well log measurements reflecting minerals and lithofacies within the logged interval. A combination of principal component analysis, model-based cluster analysis and discriminant analysis is used to characterize and identify electrofacies types. Second, we apply non-parametric regression techniques to predict permeability using well logs within each electrofacies. Three non-parametric approaches are examined viz. alternating conditional expectations (ACE), generalized additive model (GAM) and neural networks (NNET) and the relative advantages and disadvantages are explored.

We have applied the proposed technique to a highly heterogeneous carbonate reservoir in the Permian Basin, west Texas: Salt Creek Field Unit (SCFU). The results are compared with three other approaches to permeability predictions that utilize data partitioning based on reservoir layering, lithofacies information and hydraulic flow units. An examination of the error rates associated with discriminant analysis for uncored wells indicates that data classification based on electrofacies characterization is more robust compared to other approaches. For permeability predictions, the ACE model appears to be the best among the three non- parametric approaches.
Asphaltene Deposition Problems in Oil Industry with Focus on Electric Submersible Pump Applications
Authors: Limanowka W.A. Andy , Voytechek M.J. Mike
Published: December 2007

This paper was prepared for presentation at the 1999 SPE Annual Technical Conference and Exhibition held in Houston, Texas, 3–6 October 1999.
Use of Formed Metal Technology to Provide Low-Risk Solutions to High-End Multilateral Completion Challenges
Authors: Hogg W. C. , Mann T. A. , Helmer K. M. , Pieroni A. R.
Published: December 2007

A newly developed multilateral junction system utilizing formed metal technology led to the installation of the world's first Level 6 multilateral completion in the South Belridge Field near Bakersfield, California. This multilateral system provided a hydraulically sealed junction that, during installation, had an effective outside diameter less than the sum of the junction's two lateral casing legs. The junction was capable of running through standard casing and hole sizes as a result of this reduced diameter. Downhole, the junction was reformed using swaging technology. This multilateral system used conventional casing, cementing and drilling systems. In addition, no milling was required and therefore no debris was created. As a result, the overall process of creating the multilateral was simplified and associated risks minimized.

In this paper, the authors will discuss this level 6 multilateral completion including an operational description of the junction system itself. The authors will outline how the system was installed and operated, including the difficulties encountered and how lessons learned from the first installation are being applied to improve performance and process in future applications. The authors will also explain how the service company and operators worked together to finance this multilateral system such that it could be applied in a low cost, low risk environment prior to application in very high cost, high risk, environments.
Continuity Assessment through Flow-Test and Production Data in a Volcanic Formation
Authors: Nomura Masahiko , Sato Kozo
Published: December 2007

A layered model without formation crossflow can reproduce anomalous pressure behavior of well tests conducted in a volcanic gas formation. This model, however, fails to simulate production-logging and/or long-term production data for some wells, implying that interlayer crossflow cannot be neglected.

To construct a layered model with formation crossflow, horizontal permeability of not-completed intervals is predicted through log responses and vertical permeability between layers is evaluated by sensitivity studies. Resultant reservoir models can reproduce pressure-transient, production logging, and long- term production data for 20 wells. During the analyses, it is recognized that long-term production data must be honored to obtain proper estimation of lateral extents of individual layers.

The layer parameters obtained in the analyses are used to assess the degree of reservoir continuity. This information is of use in characterizing the reservoir and for a future development plan.
A Comparison of Forecasting Methods for Gas Production
Authors: Caswell G. R. , Mogensen A. C. , Trick M. D.
Published: December 2007

As the demand for natural gas has increased, so has the need for accurately forecasting reservoir deliverability. Some common methods for forecasting include (a) production decline analysis; (b) a tank type reservoir model linked to a surface network model; and, (c) a reservoir simulator linked to a surface network model. The selection of the most appropriate method should consider the economic risk associated with the forecast and the availability of pertinent data necessary for the method being applied. In reality, other considerations such as time constraints, availability of certain in-house models, or the familiarity the engineer may have with one or more forecasting methods may be the governing factor in deciding which method might be applied. The paper compares the production forecasts generated for the three forecasting methods referenced evaluating such parameters as reservoir permeability and geometry and the effect of changing backpressure and well spacing. An assessment of the impact of these parameters and the relative magnitude difference of the forecast are presented to help provide guidelines for selecting a method, and appreciating the accuracy of methods in certain circumstances.

This study found that production decline analysis generates the most conservative forecast of the three methods unless information is available to characterize the transient period in advance of the depletion decline. Production decline analysis, by virtue of its inherent assumptions, is unable to accurately predict the changes in volumes that result from changing surface operating conditions. A tank reservoir model linked to a surface network model is a good tool for field optimization, as long as the reservoirs are homogeneous and have good permeability. However, reservoir geometry can severely influence the interpreted results from such models, leading to erroneous conclusions. A reservoir simulator linked with a surface network model is the preferred choice for forecasting and optimizing the system for heterogeneous and/or low permeability reservoirs as long as sufficient reservoir data are available.
Optimizing Horizontal Laterals in a Heavy Oil Reservoir Using LWD Azimuthal Measurements
Authors: Rasmus J. , Bornemann Ted , Farruggio G. , Low S.
Published: December 2007

Over 100 horizontal laterals averaging 4,600 feet in length have been drilled in a shallow, heavy oil reservoir in Eastern Venezuela. Measurement While Drilling (MWD) continuous directional measurements and Logging While Drilling (LWD) azimuthal measurements are used to steer the wells through the reservoir, along a specific well path chosen from vertical stratigraphic wells for each pad and 3 Dimensional (3D) seismic which covers the field area.

Experience from drilling the horizontal wells has shown that this reservoir is laterally discontinuous between the vertical stratigraphic wells and that this discontinuity is not always predicted from the surface seismic. However, the LWD azimuthal measurements, presented in the form of a 3D image is able to give the orientation of the wellbore relative to the geometry of the channels. Another use of the azimuthal images is to identify the numerous shale stringers that are only a few inches thick. These stringers are not detectable on the vertical stratigraphic wells due to the limited bed resolution of the wireline logging tools run in these wells. These stringers in the laterals greatly reduce the non-azimuthal resistivity measurements and give a false indication of an approaching reservoir bed boundary.
FPSO Trends
Authors: Ronalds B. F. , Lim E. F. H.
Published: December 2007

A review of trends in floating production, storage and offloading (FPSO) technology is presented, using an extensive database of past, current and planned developments around the world. The review commences with the first FPSOs in the mid-1970s, explores the stimuli for FPSO development in Asia, in particular, over the next two decades and their widespread acceptance in the North Sea in the late-1990s. Current and future FPSO innovations in both hardware and applications are discussed against this background.
New Wireline Formation Testing Tool with Advanced Sampling Technology
Authors: Proett Mark A. , Gilbert Gregory N. , Chin Wilson C. , Monroe Myrick L.
Published: December 2007

A recently introduced wireline formation-testing tool incorporates new digital control technology to significantly improve formation fluid sampling and pressure testing. A primary focus of the new technology is improving the quality of reservoir fluid samples. An innovative pump-out design using a digital control feedback system enables the tester to continuously monitor the fluid sampled and to make precise adjustments to the rate and pressure at which the fluid is withdrawn from the formation and injected into a sample chamber. Because the tool design incorporates a powerful pumping-system motor and an efficient hydraulic system, invaded fluids surrounding the probes, such as mud filtrate, can be flushed 50% faster than other wireline test tools, thereby enabling quicker sampling of virgin formation fluids. Sample chambers can be filled against hydrostatic pressure to insure pressure-volume-temperature (PVT) quality samples, and additional pressure can be applied to minimize phase changes that might otherwise occur because of temperature gradients in the borehole. The new system can also be used to perform a closed-chamber PVT test for the bubble point of the fluid sampled.

Closely spaced dual probes are simultaneously deployed for pressure testing and fluid sampling. Besides increasing tool reliability through redundancy, the two probes allow for advanced pressure-testing techniques. For example, formation anisotropy can be determined with an interference test between the two probes. Alternatively, a new pressure-pulsing technique can be used, which uses time delays between the probes’ measured pressures to determine additional hydraulic diffusive properties of the formation. The drawdowns can be rate- or pressure-controlled from either probe.

The new tester is combinable with existing openhole logging tools and tester tool sections are interchangeable. This combinability permits a complete wireline toolstring to be configured to meet particular openhole formation evaluation and testing needs in a single trip into the well. Current tool sections for the new tester include a dual-probe section (DPS), flow-control pump-out section (FPS), precision quartz gauge section (QGS), chamber valve section (CVS) for two sample chambers (1 to 5 gallon), and a multi-chamber section (MCS) with 1,000-cm3 chambers. The MCS chambers are compatible with hydrogen sulfide (H2S) with NACE approved materials and have an exemption with the U.S. Department of Transportation (DOT) for common-carrier transportation.

This paper details operational features of the new tester and introduces new pressure-testing and sampling interpretation techniques. Field-test results are used to demonstrate these features and techniques.
An Analytic Model for a Flowing Bundle System
Authors: Danielson Thomas J. , Brown Lloyd D.
Published: December 2007

As bundled pipelines have become more common in offshore operations, several tools have appeared to aid in the modeling of such systems. One such tool is the Conoco bundle model, developed for use with the OLGA transient multiphase code, and used extensively on Conoco's Britannia bundle system (SPE 36610)1 and commercialized by Scandpower. However, if the numerical grid is not sufficiently fine in regions of large axial temperature gradients, the temperature profile in the bundle lines will not be adequately captured. This can result in a significant over-prediction of minimum line temperatures (and possible formation of hydrates and paraffin), and significant under-prediction of thermal stresses.

Many times, a steady-state analysis is adequate to capture most of the salient features of a bundle system. With minimal simplification, an analytic solution for a steady-state bundle system containing up to 3 internal lines (e.g., the production and test line, and heating medium return line) can be formulated.

The Conoco Analytic Bundle Model has the advantage that it is not grid-sensitive, as the numerical model is. In addition, unlike the numerical model, it is extremely fast (essentially instantaneous) and easy to set up. For this reason, it is an excellent tool for performing sensitivity analyses on variables which cannot be predicted with great accuracy, e.g., the film heat transfer coefficient in the bundle heating medium.
Downhole Water Sink (DWS) Completion Enchance OIL Recovery in Reservoirs with Water Coning Problem
Authors: Wojtanowicz A. K. , Shirman E. I. , Kurban H.
Published: December 2007

To date, field trials of wells with DWS completions have shown that this new technology could control water coning and increase oil production rate. None of these tests, however, was long enough to show DWS potential to improve process of oil recovery comparing to conventional wells. Presented in this paper are results from a recent project of the R&D consortium of nine companies at LSU – Downhole Water Sink Technology Initiative.

The recovery study involved experiments with the physical model and computer simulation runs. The laboratory results showed that, for the same rate at the top completion, DWS dramatically accelerated the recovery process; A five-fold increase of the oil production rate was reached without changing the rate at the top completion - by adjusting the drainage rate at the bottom completion. The results also showed a 70-percent increase of oil recovery; from 0.521 up to 0.882 for conventional and DWS completions, respectively.

The computer-simulated experiments with commercial reservoir simulator confirmed the thesis on better recovery with the DWS completions by showing a 30-percent increase of recovery factor from 0.61 to 0.79 for conventional and DWS completions, respectively. The results also gave a five-fold reduction of the time required to reach the limiting 0.98 value of water cut. However, accelerated recovery process with DWS required a substantial up to 3.5-fold increase of total water production.

The simulation experiments clearly showed that the main advantage of using DWS is its flexibility of controlling the recovery process. For conventional completions, the recovery could be slightly increased by reducing production rates and largely increasing production times. For DWS, on the other hand, production process could be optimized for maximum recovery, minimum time, or minimum cumulative water produced by seeking a best combination of the top and bottom rates.
Time Lapse Ultrasonic Measurements of Laboratory Hydraulic Fracture Growth: Width Profile and Tip Behaviour
Authors: Groenenboom J. , van Dam D. B. , de Pater C. J.
Published: December 2007

In scaled laboratory tests, we perform acoustic measurements in a time-lapse sequence to separate the fracture response from the background signal. Using both compressional waves and shear waves (that are very sensitive to fluid filled fractures) we can not only detect the hydraulic fracture, but also characterize its shape and geometry during its growth. We show the application of the technique to propagation, flowback tests and re-opening of hydraulic fractures.

During fracture growth the acoustic waves excite diffractions at the tip of the fracture. We use the direct compressional and shear diffractions to locate the position of the tip of the fracture. The ultrasonic data show that the diffractions are most strongly excited at the fluid front of the hydraulic fracture. In some cases, a much weaker precursor diffraction can be detected which is interpreted as the dry tip of the fracture. Depending on the acquisition geometry, we detect many events related to surface waves propagating along the fracture. Also, we observe that shear waves detect the migration of the fluid front during re-opening of a pre-existing hydraulic fracture, in contrast with the compressional waves which are insensitive to the fluid front during re-opening.

Observation of transmission signals through the fracture yields a very accurate measurement of the fracture width. In this way we have obtained the full fracture width profile during propagation and closure. Flow back resulted in closing the fracture at the wellbore, while it remained open farther from the wellbore.
Interpretation and Modeling of Time-Lapse Seismic Data: Lena Field, Gulf of Mexico
Authors: Shyeh J. J. , Johnston D. H. , Eastwood J. E. , Khan M. , Stanley L. R.
Published: December 2007

Two 3D seismic data sets from the Lena Field, Gulf of Mexico are analyzed for time-lapse effects. The seismic analysis involves cross equalization and residual migration of the post-stack seismic data, as well as full reprocessing and attribute analyses. The time-lapse differences for the B80 reservoir are compared with production data, geologic models, flow simulations, and forward seismic models. The time-lapse seismic difference anomaly is interpreted to be a region of gas invasion. Areas bypassed by the injected gas are identified from 4D seismic data as opportunities for infill drilling. Successful interpretation of this time-lapse seismic data illustrates the importance of integrating the results of modeling and simulation with seismic processing and interpretation.
Application of Silicate-Based Well Treatment Techniques at the Hungarian Oil Fields
Authors: Lakatos I. , Lakatos-Szabó J. , Tiszai Gy. , Palásthy Gy. , Kosztin B. , Trömböczky S. , Bodola M. , Patterman-Farkas Gy.
Published: December 2007

By joint application of silicates and polymers or humates, a multifunctional, self-controlling chemical system is usually formed which works spontaneously even under harsh reservoir conditions, meanwhile the methods remain inexpensive, flexible and adaptable to any production technology. A concise summary of the diverse techniques, their principle and mainly field projects are discussed in the paper. It was shown that the silicates, combined with polymers and humates offer unique opportunity to cure numerous production/injection problems including water-shut-off, profile correction, clay stabilization, etc. in oil and gas fields and underground gas storage. Between 1980 and 1998 the field projects, comprising more than hundred well treatments, yielded substantial additional oil production, life time of wells were extended and the overall profitability of fields was significantly increased, meanwhile environmentally friendly chemicals were used. Therefore, the Hungarian experts are convinced that the silicate-based methods as reasonable alternatives wherever and whenever the application of bulk or surface gelation or deposition is arising.
Fully Automatic Procedure for Efficient Reservoir Fluid Characterization
Authors: Liu K.
Published: December 2007

The EOS has been widely applied to characterize reservoir fluids. On the other hand, an EOS is generally not predictive without tuning its parameters to match relevant experimental data. Since the manual EOS-tuning process is artistic and strongly dependent on an engineer's past experience, different engineers may get completely different results and few engineers could obtain the satisfactory results without certain tries and guesses. Problems include what the minimum number of components should be used, how the original system should be lumped, how many and what kinds of regression variables should be included into the regression variable set, and so on. This paper presents a fully automatic technology to efficiently perform the reservoir fluid characterization. A method to handle multiple fluid samples, a fully automatic tuning procedure, a best lumping algorithm, and the fully automatic determination of the minimum number of components will be described. Some applications will be summarized.
Gradient-Based History-Matching with a Global Optimization Method
Authors: Gómez Susana , Gosselin Olivier , Barker John W.
Published: December 2007

We investigate the application of a global optimization algorithm called the Tunneling Method to the problem of history-matching of petroleum reservoirs.

Results are presented for two test cases. The first is a small synthetic case in which the global minimum is known. The second is a real field example. In both cases, a series of minima was found. The computational cost of each tunneling phase is found to be comparable with the cost of each local minimization.

It is concluded that the Tunneling Method may have a practical application in history-matching as an alternative to immediate reformulation of the problem if the first minimum found does not represent an acceptable match.
Time-Dependent Coupled Processes in Wellbore Design and Stability: PBORE-3D
Authors: Abousleiman Y. , Ekbote S. , Cui L. , Mody F. , Roegiers J. -C. , Zaman M.
Published: December 2007

It is well established that time-dependent processes are responsible for stability and failures in wellbore drilling. Stability problems account for a significant amount of lost drilling rig time and substantial costs during drilling. The coupled time-dependent processes are well described in the realm of the poroelasticity theory and some of their solutions and applications to the inclined wellbore problem in the general three-dimensional state of the in-situ stress have been published. In this paper, in addition to the analyses conducted on the previously derived solutions, thermal and pore fluid diffusion, the time-dependent solution for stresses and pore pressure for the inclined wellbore taking into account the mud and formation shale activities, are also derived. The aforementioned solutions are implemented in the user-friendly software, PBORE-3D, which can perform analyses of stress/pore pressure, formation failure, mud weight and mud salinity design for drilling in shale formations. Also included in this software are the thermal and viscous effects.
Optimization of Multistring Casing Design with Wellhead Growth
Authors: Samuel G. Robello , Gonzales Adolfo
Published: December 2007

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

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

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

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

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

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

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

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

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

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.