bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sustaining Surface Casing Integrity In A Saline Environment
Authors: Fanoiki J. B. 
Published: December 2007

Abstract
The bulk of Nigeria’s oil and gas production come from the Niger Delta area of the country. The environment is generally susceptible to high salinity, which influences quick set in of external corrosion on metallic products.
The surface casing of wells located mostly in the swamps of the Niger Delta are prone to external corrosion attack at the splash zone around the wellhead region. The effect of this corrosion ultimately results in loss of load bearing capacity of the wellhead when the severity is very high. At rig based well reentry, collapse of the surface casing had occurred under the weight of the Blow Out Preventer (BOP) during its installation. Repair of such failure at the wellhead is mostly unplanned and can be expensive.
The external corrosion at the wellhead region is influenced by the oxygenation of rainwater retained in the annular space between the conductor pipe and the surface casing. Similarly, the cement micro annulus that emanates behind the surface casing tend to retain some relatively small amount of water which invariably do cause an invisible, slow but steady development of corrosion on the surface casing.
The proposed paper will proffer solutions to incidence of external corrosion on the surface casing with a view to enhancing production life, safety and reducing operating cost.
The Exploitation Enigma
Authors: Etherington John R. , Leach Patrick E. , Slaght David H. 
Published: December 2007

Abstract
Evaluation of exploitation drilling programs raises unique issues around risking logic plus estimated ultimate recoverable (EUR) and project economic uncertainties. Clarification of these issues will assist in managing portfolios of exploration, exploitation, and development investment opportunities.
Under USA accounting rules, all wells drilled outside the area of proved reserves are classified as "exploratory wells" for computation of cost of finding. However, companies typically segregate wells into Exploration (targeting prospective resources in undiscovered accumulations) and Exploitation (targeting probable and possible reserves in and around discovered fields).
Classification as "discovered" signifies a high degree of confidence that the accumulation's EUR exceeds an internal economic threshold for development. However, there remains significant risk of drilling a dry well within the projected field limits. At the field level, the non-proven area is part of the uncertainty distribution for discovered reserves. At the exploitation well level, risk of failure and success case volume uncertainty both come into play. This multiple level view of risk and uncertainty gives rise to the "exploitation enigma".
Exploitation well results change the field/reservoir model, the EUR uncertainty profile and associated cash flow projections. Successful wells not only develop reserves within a drainage area but also modify the total field volume uncertainty distribution. Results redefine the remaining proved undeveloped, probable, and possible reserve volumes and their associated confidence levels. Dry exploitation wells also
change the EUR distribution and increase investment costs without an increase in forecast production.
This paper compares alternative approaches to the evaluation of exploitation programs. It concludes that the economic analysis to support exploitation drilling decisions should not be based solely on the individual well's anticipated results, but rather on its risk-weighted, incremental effect on the overall project value.
Ceiba Completion Optimization: A Fast-Track Approach to Success
Authors: Claiborne E. B. , Malone B. P , Marshall J. C. 
Published: December 2007

Abstract
Triton Energy Ltd. (Triton) (acquired by Amerada Hess Corporation in August 2001) and Energy Africa (15% WI), set a benchmark for the oil industry by discovering and developing a deepwater Equatorial Guinea, West Africa field and establishing production to a FPSO in less than 14 months. The fast-track development project operated by Triton commenced in October 1999 following the Ceiba-2 confirmation well. The completion strategy and its success played a major role in realizing this world record achievement and continually improving well performance in the Ceiba field.1
As with any new field, development of the optimum completion strategy evolved based on lessons learned. Eight (8) producers, one (1) sidetrack and three (3) water injection wells have been completed to-date. The initial five (5) production wells (Phase I), utilized cased-hole completions. Four of these five wells employed single-trip perforating and gravel pack (STPGP) completion techniques. These completions produced upwards of 18,000 bopd with moderate skins. The fifth cased hole production well was completed using a single-trip perforating, gravel pack technique in conjunction with a hydraulic fracture treatment (STPFP). This resulted in an improved skin factor and Productivity Index (PI). The remaining three (3) producers were completed as open hole gravel packs using mineral oil based mud (MOBM) as the reservoir drill-in fluid (RDF). Three seawater injection wells have also been completed to date. Two (2) were performed as STPGP's and one (1) as a STPFP. These recent changes of methodology have proven successful in further enhancing productivity index and reducing skins.
The versatility and flexibility required to successfully incorporate the required strategy changes in such a short time frame, reflects the weighted risk taking approach and aggressive management style of the operating company and a strong commitment of the service sector.

Major Contributors to Project Success
Drilling Fluid Sweeps: Their Evaluation, Timing, and Applications
Authors: Hemphill Terry , Rojas Juan Carlos 
Published: December 2007

Abstract
Drilling fluid sweeps are commonly run in the field to help clean the borehole of cuttings that have not been removed with normal fluid circulation. Typically, these sweeps are used in vertical and deviated drilling operations. In high angle or extended reach wells, their use can be helpful in removing cuttings that have accumulated in sections where hole cleaning is not optimized. Sweep types usually fall into the following categories:
High-viscosity High-density Low-viscosity Combinations of any 2 of the above Tandem (one type followed by another)
Their effectiveness in the field is often quite spotty, often due to the application of a certain sweep type in the wrong drilling situation. Heretofore, there has been lacking a rigorous method of evaluating the effectiveness of sweeps at the rig site. Usually sweeps have been evaluated in the field based on observed or perceived quantities of cuttings coming over the shakers, a methodology that can be very subjective.
In this paper, a rigorous method of evaluating drilling fluids sweep efficiency is proposed. Here, information from pressure-while-drilling (PWD) tools and measured drilling fluid and sweep fluid properties is used to determine a mathematical prediction of "cuttings out". In short, the method relies on the difference between "mass in" and "mass out". Examples from field applications are given to illustrate the usefulness of this methodology.
With a more rigorous evaluation of drilling fluid sweep efficiency in hand, users can objectively determine the type and frequency of application of drilling fluid sweeps and rig time spent circulating out ineffective sweeps can be minimized.
Mechanisms of Bubble Formation by Pressure Decline in Porous Media: A Critical Review
Authors: Bauget F. , Lenormand R. 
Published: December 2007

Abstract
The modeling of primary production of heavy oils by solution gas drive is an active area of research. All the models, either written at Darcy scale or at pore scale (capillary network, population balance), account for the following mechanisms: bubble formation, bubble growth and gas flow. The first stage of bubble formation, also called bubble nucleation, is still controversial. In this paper, we discuss the existing nucleation models and demonstrate that the preexistence of bubbles is the only theory that is justified physically and can explain the ensemble of experimental observations. The preexisting bubbles are stabilized either by surfactants (models used for cavitation studies) or capillarity in crevices (models used in boiling). In both models, a given number of bubbles are activated at a given pressure drop. The only adjustable parameter is the distribution of diameters of the preexisting bubbles. This distribution is a property of the rock/fluid system that can be experimentally determined.
The other models used in literature are based on the formation of a stable nucleus by thermal fluctuations. They lead to the notion of nucleation rate that is in contradiction with experimental results.
We also discuss the terminology used in recent papers. Especially the terms of "instantaneous nucleation" and "progressive nucleation" are irrelevant if a mechanism of preexisting bubbles is assumed. They are also misleading since they lump the mechanism for bubble formation (statistics or preexistence) and the mechanism for pressure decline (either step or constant rate).
Investigation of the Relationship Between the Dimensionless and Dimensional Analytic Transient Well Performance Solutions in Low-Permeability Gas Reservoirs
Authors: Poe B. D. , Marhaendrajana T. 
Published: December 2007

AbstractThis paper presents the results of an investigation into the relationship between the dimensionless and dimensional pressure and rate-transient solutions of wells completed in low-permeability gas reservoirs. Solutions of the linear diffusivity equation are commonly used to model the performance of gas reservoirs using the pseudopressure and pseudotime integral transformations to account for the nonlinear fluid properties in the system and to effectively linearize the problem so that linear solutions can be utilized in the analyses.Transient analysis techniques have been developed that improve the accuracy in estimating values of the pseudotime integral transformation, thus improving the accuracy of evaluating the reservoir and well properties from the production performance of low-permeability gas reservoirs, using analysis models based on analytic solutions of the linear diffusivity equation.
Interactions Between Drilling Fluid and Reservoir Fluid
Authors: Bureau N. , de Hemptinne J. C. , Audibert A. , Herzhaft B. 
Published: December 2007

Abstract
Severe environmental regulations lead to the use of biodegradable base oils such as heavy esters of fatty acids from natural origin for drilling applications. An appropriate knowledge of the gas solubility within the fluid in the well is essential for preventing risk of gas kick and gas hydrate formation whatever the pressure and temperature conditions. No relevant literature data exist for such long and polar alkyl chains in interaction with hydrocarbons coming from the reservoir. For this purpose, our study focuses on experimental data acquisition and modelling of both bubble pressures and densities for gas – oil mixtures i.e. ester – toluene – methane mixtures.
Bubble pressures are measured at 323.15, 363.15 and 393.15 K and densities at different pressures for each temperature.
Model compounds have been first used in order to allow the development of a predictive method. For validation purposes, measurements have been performed on a real reservoir fluid with an ester phase. Water and an emulsifier have been then added in order to evaluate their effect.
In a second step focused on modelling, high pressure phase equilibria are described using an equation of state. However, the classical cubic equations do not perform well since they don't take into account the possible molecular associations. Another equation has therefore been tested.
The chosen model is based on the Elliott-Suresh-Donohue equation of state; it uses the classical mixing rule and contains a term for association between molecules. The pure component parameters are calculated from the corresponding states principle, with the Somayajulu critical parameters. It allows an encouraging predictive description of the experimental results.
In order to improve the gas – oil equilibrium prediction, we propose correlations for binary interaction coefficients between methane and esters, and between methane and aromatic molecules.
Similarly, the description of the densities is improved by using a correlation for the volume translation.
Both of these correlations are dependent on the temperature and the molecular weight of the mixture components.
With this model, it is now possible to describe the phase equilibria of methane – heavy esters systems in a totally predictive way, with an accuracy of 16% (maximum 50 bar error) and to reproduce the volumetric properties with an error of 6%.
The final aim of this work is the study of a real oil based mud taking into account the presence of brine in our systems.
These systems will also be investigated at low temperature in order to describe the deep offshore conditions.
Design, Calibration, Characterization, and Field Experience of New High-Temperature, Azimuthal, and Spectral Gamma Ray Logging-While-Drilling Tools
Authors: Mickael M. , Phelps D. , Jones D. 
Published: December 2007

Abstract
Two new gamma ray tools have been developed, one provides high temperature total gamma ray measurements, and another delivers spectral gamma ray measurements while drilling. The high-temperature gamma ray tool can operate at temperatures up to 356°F (180°C) and survive to 392°F (200°C). It uses multiple two-detector banks of Geiger Muller Tubes. Five banks are used in the 4.75" tool and eight banks are used in the 6.75" and 8" tools. The tubes are arranged symmetrically to provide azimuthal measurements while rotating and/or sliding. The new spectral azimuthal gamma ray tool (SAGR) employs three high-efficiency scintillation detectors symmetrically arranged around the center bore of the drill collar. This design provides a superior total gamma ray measurement and spectral capability that has equivalent accuracy to a wireline spectral gamma ray tool.
Calibration of LWD gamma ray tools has always been problematic because the main gamma ray calibration facility at the University of Houston has a smaller borehole than the collar size of the majority of LWD tools. A procedure was developed to calibrate LWD gamma ray tools when the collar size exceeded 4.75" and could not be conventionally lowered into the API pit. Measurements were made with a 4.75" LWD tool in the University of Houston gamma ray formation to obtain an absolute reference standard. The tool was then used to create two secondary standards with larger boreholes to be able to calibrate larger-size tools. Comprehensive computer modeling was performed to validate the API measurements and develop environmental corrections.
The new spectral gamma ray sensor provides real-time K, U, and Th measurements. The spectral data of the three detectors are first aligned to a standard spectrum to compensate for gain changes due to temperature and electronics drift. The count rates are then summed and a full-spectrum least squares fit to K, U, and Th reference standards is applied to determine the K, U, and Th contents of the formation. The measurement is calibrated to the KUTh API standards at the University of Houston.
Details of the calibration, processing, and correction algorithms are presented. Field examples are presented to illustrate the applications, accuracy, and repeatability of the measurements.
Increasing Separation Capacity with New and Proven Technologies
Authors: Chin R. W. , Stanbridge D. I. , Schook R. 
Published: December 2007

Abstract
Compact separation has been a "buzz" word in design of new facilities for many years now as more reserves are being located in deeper waters. However, upgrading existing facilities to handle more production is also important. Third party processing, under-estimated reserves, or recently located nearby reserves result in higher rates. Space then becomes a premium especially in the deep water facilities where extra space may have been minimal in the design. This paper will discuss some new and proven technology not only for compact separation, but also for increasing gas/liquid separation capacities of existing vessels. Applications of the technologies will also be presented.
Rheology and Special Requirements on the Flow System and Equipment for Large Scale Injection, Production and Gathering of Viscous-Elastic Polymer Fluids in Chemical Floods and Methods to Solve the Problems that Emerge
Authors: Wang Demin , Youlin Jiang , Wang Yan , Gong Xiaohong , Wang Gang 
Published: December 2007

Abstract
Most flow systems and equipment for the injection, production and gathering of large amounts of fluid are designed for Newtonian fluids. Now, an increasing number of oil fields are on viscous-elastic flooding (for example, Daqing Oil Field alone injects and produces more than 70 million m3 of viscous-elastic fluid containing polyacrylamide [PAM] per year). After flooding by PAM fluids, besides an increase in recovery (in Daqing, the recovery increases more than 12% OOIP [original oil in place]), decrease in water cut (from more than 90% to about 70%), increase in production (in year 2001, Daqing produced about 9.8 million tons of oil by PAM flooding), it was seen that the flow of this type of fluid in production and surface systems and equipment has its special characteristics which in turn require special designs for the equipment and flow process. Otherwise, the efficiency and service life of each equipment and system will be low, energy consumption and mechanical degradation of polymer fluid high and vibration in the whole system serious. Sometimes, normal operation cannot be maintained.
This paper introduces the actual performance of the production and surface flow systems and equipment, points out the influence that the special rheologic characteristics, especially the viscous-elastic nature of the fluid, has on the system and the modification made. For example, there is a normal force acting on the beam pump sucker rods that cause pronounced eccentric mechanical wear on one side of the sucker rods and thereby very short service life span of beam pump wells; this normal force significantly lowers the efficiency of centrifugal pumps; increases the vibration and mechanical degradation in triplex pumps and the whole system; lowers the efficiency of maturing tanks and static mixers etc.
The modifications on the system and equipment and its results are shown. For example, the service life of beam pumps more than doubled; mechanical degradation of polymer in the system and triplex pumps decreased more than 50% and 70% respectively; and the energy consumption of mixing equipment decreased 80% etc.
The above should be of value to oil fields preparing to use large amounts of viscous-elastic fluids to increase oil recovery.
Modeling Reservoir/Tubing/Pump Interaction Identifies Best Candidates for Multiphase Pumping
Authors: Martin A. M. , Scott S. L. 
Published: December 2007

Abstract
Multiphase production systems are being considered as a development option for many fields on a worldwide basis. Engineers are faced with the challenge of selecting the best candidates to take full advantage of this novel technology. A review of the literature reveals that no guidelines have yet been published regarding this issue. This paper utilizes classical reservoir engineering methods to model the interaction of a surface installed multiphase pump with the reservoir and tubing. A derivative analysis of the backpressure equation is used to show the difference in incremental production among wells with different backpressure coefficients and exponents. A method was developed which combines well deliverability and decline data to forecast the impact of a multiphase pump on reserves, i.e. ultimate recovery. The results of this study indicate that: 1) wells exhibiting a low wellhead backpressure coefficient (n) make poor candidates for multiphase pumping; 2) plotting the derivative of the wellhead backpressure equation provides a means of defining a threshold, which must be reached before a multiphase pump, would provide value; 3) liquid loaded wells may yield the best response to a surface installed multiphase pump; and, 4) reduction of the backpressure on a well, through use of a multiphase pump, acts to increase the ultimate recovery for a well or field.
An Integrated Reservoir Characterization Study Matching Production Data and 4D Seismic
Authors: Kretz Vincent , Le Ravalec-Dupin Mickaële , Roggero Frederic 
Published: December 2007

Abstract
Our purpose is to evaluate the benefit of using time-lapse seismic in addition to production history for reservoir characterization. A new inversion methodology, based on the gradual deformation method, has been developed to integrate simultaneously different sources of information like 4D seismic related data and production data. This methodology was successfully validated on a geologically realistic 3D synthetic reservoir model.
An optimization procedure was developed to identify reservoir models consistent both with a first 8 year period of production data and 4D seismic related data. It is based upon two complementary numerical tools developed at the IFP: the FFT-MA generator and the gradual deformation method. The first one generates stochastic realizations for the reservoir model. The second one allows us for perturbing the realizations from a small number of parameters while preserving the spatial variability model. The optimization process was repeated starting from different initial reservoir models. The predictive quality of the constrained reservoir models was estimated comparing the simulated forecasts and the reference data for a second 8 year period of production data.
The proposed inversion method proved its efficiency for constraining geostatistical reservoir models to different sources of data. It is shown that conditioning reservoir models to saturation changes in addition to production data allows for improving significantly the reliability in the production forecasts.
Effects on Well Test Analysis of Pressure and Flowrate Noise
Authors: Archer R. A. , Merad M. B. , Blasingame T. A. 
Published: December 2007

Abstract
We have utilized sets of simulated well tests in an example well/reservoir model with an unfractured vertical well or a vertical well with a finite-conductivity (vertical) fracture to demonstrate the dependence of the estimated parameters and their confidence intervals on noise in the pressure and flowrate data. Uniformly distributed random noise is introduced into the pressure data and the resulting well parameter estimates are obtained using conventional means (analysis/history matching).
For the cases of a pressure buildup test in an unfractured well and the pressure drawdown cases performed on a fractured well, the estimated parameters are almost without bias — and the confidence intervals grow linearly with the magnitude of the noise. For the cases of pressure buildup tests performed on the fractured well, the estimated parameters are insensitive to the noise — which suggests that this case may not be well-posed for analysis.
Gauge drift and flowrate noises were also considered and the analysis results from the example well tests demonstrate that both of these kinds of noise are handled robustly by conventional well test analysis techniques.