bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Flow Performance of Velocity Strings to Unload Wet Gas Wells
Authors: Oudeman P. 
Published: December 2007

Abstract
In depleted gas wells, the produced gas rate and consequently the velocity will drop to the extent that produced liquids are no longer carried to surface. The liquids accumulate in the well bore, increasing the sand face pressure. This further reduces the inflow, so that more liquid collects and eventually the flow dies down completely. This phenomenon is known as liquid loading.
Velocity strings are a commonly applied remedy to liquid loading in gas wells. By installing a small diameter string inside the tubing, the flow area is reduced which increases the velocity and restores liquid transport to surface. The disadvantage of the velocity string is the increase in frictional pressure drop, constraining production. Hence an optimal velocity string has to be selected such that liquid loading is delayed over a long period with a minimal impact on production. This requires accurate methods to predict pressure drop in the velocity string as well as tubing-velocity string annulus.
The available methods to predict pressure drop in annuli for gas-liquid flow are modifications of methods to predict wet gas pressure drop in tubing. These modifications are usually based on assumptions, which are strictly valid only for single-phase flow. Their validity for gas-liquid flow is questionable. Hence to assess the validity of the methods a field test was designed and executed. The results were compared with various approaches to describe wet gas flow in an annulus. This allowed selection of the best approach with an accuracy comparable to the accuracy of methods to predict pressure drop in tubing. Factors affecting the accuracy were identified. Comparison with a field case provided further proof for the validity of the approach.
This result is not only relevant for velocity string design, it is important for all annular flow processes in wells such as flow around a stinger, drill pipe, tool or coiled tubing string.
Hydrocarbon Potential Monitoring in Gas Sandstone Reservoirs Using TDT and CHFR Techniques
Authors: Hamada G. M. , Hegazy A. A. 
Published: December 2007

Abstract
The ability to detect and evaluate bypassed hydrocarbon and track fluid movement in sandstone reservoir is vital in the quest to improve production and increases recovery. The main technique, which has been used for monitoring reservoir saturations, is Thermal Decay Time (TDT) tool. But, it was hard to interpret the TDT data in the low formation water salinity reservoirs. This problem can not be solved because it is related to the theory itself of TDT measurement, which depends on salt content in formation brine. The problem of low formation water salinity was solved by Carbon Oxygen Ratio (COR) technique, which was latterly combined with TDT technique in the same tool, called reservoir Saturation Tool (RST) tool. This tool was not widely used due to its short depth of investigation (6-8 inches) in addition to its long logging time.
A Technique called Cased Hole Formation Resistivity tool (CHFR) technique was proposed to overcome many of the pulsed neutrons tool limitations. Based on the actual CHFR logs recorded through wells studied in an oil field in Sinai, which are presented and discussed in the present work, a comparison study was done between the two available techniques, TDT and CHFR as methods for reservoir saturation monitoring, in addition to the results of open-hole resistivity logs as reference runs. It was found that water saturations calculated from CHFR logs were more accurate than TDT log in most of the cases, and that the quick look of CHFR logs always agrees with its quantitative interpretation, which gives the trust to relay on quick look of CHFR log, if a fast decision is required. While the quick look of TDT log was found to be very tricky, in most of the cases: often does not agree with its quantitative interpretation.
A Case Study in the Removal of Deposited Wax From a Major Subsea Flowline System in the Gannet Field
Authors: Craddock H. A. , Mutch K. , Sowerby K. , McGregor S. , Cook J. , Strachan C. 
Published: December 2007

Abstract
The chemical removal and dissolution of deposited wax has been described and proven in a variety of applications. This paper describes in detail the removal of wax deposits from a major subsea flowline with the use of a chemical dissolver.
The following stages were key to the successful wax removal operation; selection and design phase of the chemical application, the chemical environmental selection criteria, the development of the work scope, as well as the mobilisation and logistics of the chemical application. This paper will illustrate the challenges faced as well as the novel monitoring and analysis techniques used in the field to determine the level of wax dissolution in situ.
The wax removal process was deemed successful and offered the client significant benefit in terms of increased oil production. Reduced pipeline differential pressure and increased fluid arrival temperatures also indicated that the wax restrictions in the flowlines had been significantly removed. In addition, the impact on the platform processing facilities during final fluid displacement was much less than anticipated and occurred with no major concerns.
A chemical dissolver application of this magnitude is thought to be unique, indeed a world first. The application was conducted in the Gannet D Field in the UK sector of the North Sea to remove wax deposits from two 16 km 6" subsea production flow lines.
The Application of Wax Dissolver in the Enhancement of Export Line Cleaning
Authors: Craddock H. A. , Campbell E. , Sowerby K. , Johnson M. , McGregor S. , McGee G. 
Published: December 2007

Abstract
Paraffin deposition in oil export pipelines can prove problematic during "intelligent pigging" operations, when hydrocarbon deposits on pipe walls are not removed sufficiently during the cleaning phase. This gives rise to sensor clogging and lift-off causing inaccurate and in some cases complete loss of data from the inspection tool. In pipelines where paraffin deposition has caused problems, specific wax dissolvers in tailored treatments have been applied during pigging programmes to aid the removal of deposits from pipe walls and to prevent further wax deposition. This paper will discuss the selection and application of these wax dissolvers and the results obtained on applying the products in field.
The laboratory methods used to evaluate and select a wax dissolver and the process of modifying the amount of chemical required will be discussed in this paper. The paper will also discuss the interaction of these dissolvers with specific hydrocarbon deposits. Furthermore, we will compare the characteristics of wax deposits retrieved from pigging programmes prior to and during dissolver application.
This paper will demonstrate that in certain North Sea fields the physical characteristics of pig waxes altered when dissolver was applied, allowing hydrocarbon deposits to be removed more effectively from the export pipeline and enhancing the cleaning phase of the pigging programme.
The application of wax dissolvers prior to and during export pipeline cleaning programmes, in preparation for intelligent pig runs, has proven beneficial where waxy crudes are being exported. The introduction of such chemical injection regimes has improved the removal of hydrocarbon wax deposits from export pipelines and has allowed meaningful data to be retrieved during intelligent pig runs.
A Novel Stimulation Technique for Horizontal Openhole Wells in Carbonate Reservoirs: A Case Study in Kuwait
Authors: Uddin Shahab , Liu Hai , Coston Chad , Yassin Mohamed , Al-Dhafeeri Fahad 
Published: December 2007

AbstractEffective matrix acidizing in Kuwait's horizontal openhole wells is a real challenge. Reservoir heterogeneity and the length of the horizontal wells make acid placement and diversion difficult, particularly in high water-cut wells in which bottom water has broken through high permeability streaks or natural fractures. Furthermore, acid penetration is limited by the large surface area of the horizontal wellbore and is exacerbated by the relatively small injection rate imposed by the use of coiled tubing. To make matters worse, formation damage in horizontal wells is usually deep due to long exposure times.This paper discusses the application of a new viscoelastic surfactant-based, self-diverting acid system for stimulation of more than 20 horizontal openhole wells in carbonate reservoirs in Kuwait. The application also deployed a new non-particulate material that forms a highly viscous plug when it contacts water, and degrades when mixed with oil in the formation. The new fluid system is pumped prior to the acid treatment to effectively prevent the acid from stimulating high water saturation sections.The field results show significant improvement on post stimulation production owing to effective diversion and water production control, compared with wells in which a conventional polymer diversion technique was used in the past with no consideration of high water cut cases. The new technique has been selected as the standard stimulation practice in most horizontal openhole carbonate wells in Kuwait.
Innovative and Interactive Produced-Water Information Resource
Authors: Veil J. A. , Puder M. G. , Sullivan R. G. , Richmond P. D. , Kotek T. J. 
Published: December 2007

Abstract
Produced water is the largest volume waste stream generated during oil and gas production. Management of produced water can be costly. The industry can benefit from having readily available and unbiased information on produced water management options and regulatory requirements. This paper describes a new web-based Produced Water Management Information System (PWMIS) being developed by Argonne National Laboratory. PWMIS includes three functional modules:
A Technology Description Module, which provides basic information about practices that are currently employed to manage produced water. Users can click on any of the listed technologies to access separate fact sheets describing each technology and including references for additional information. A Regulatory Module, which identifies and summarizes existing state and federal regulations or guidelines on produced water management. Users can click on EPA, BLM, MMS, or on any state to be sent to pages that offer more information about each agency's requirements. A Technology Identification Module, in which users are asked to answer a series of questions. The replies to these questions lead users through a decision tree, resulting in a suggested subset of water management options that would make the most sense for a given geographical or environmental setting.
PWMIS is based on the successful Drilling Waste Management Information System website (http://web.ead.anl.gov/dwm) developed by Argonne in 2004. PWMIS is expected to be available to users by mid-2007.
Cementing Considerations for Casing While Drilling: Case History
Authors: Strickler Robert D. , Solano Pablo 
Published: December 2007

Abstract
Casing while drilling (CWD) is an emerging technology being introduced in different areas around the world This new configuration, where the casing is used as a drillstring, presents new challenges for primary casing cementing operations compared to the conventional cementing operations.
A full understanding of the required changes of the cementing methodology from conventional drillpipe drilling operations can contribute to the success of any CWD campaign. CWD cementing differs from conventional cementing practices because it is impossible to use standard centralizers attached to the casing while drilling because of extended and faster casing rotation.
When more than one bit is required to reach the next casing point, CWD requires full-bore casing access to pull and run bottomhole assemblies (BHA) through the casing. In these instances, conventional floating equipment cannot be used.
Wireline logging is normally conducted in cased hole after the cementing job. The cement volumes are calculated with a cement excess factor instead of a caliper log.
This paper describes the methodology developed to successfully cement surface, intermediate, and production casings in more than 125 wells in south Texas where CWD was used. These same techniques can be applied in CWD operations elsewhere.
Squeeze Chemical for HT Applications – Have We Discarded Promising Products by Performing Unrepresentative Thermal Aging Tests?
Authors: Wat Rex , Hauge Lars-Even , Solbakken Kåre , Wennberg Kjell Erik , Sivertsen Linda Merete , Gjersvold Berit 
Published: December 2007

Abstract
Selecting an effective scale inhibitor for squeeze application at 170°C is no simple task. The traditional thermal stability test by aging the chemical in bulk is often perceived to be too harsh. This results in many promising products being rejected due to their apparent degradation at temperature. The alternative of conducting aging test inside core materials, hence more representative to the downhole conditions, is NOT a novel idea. However, no definitive data is available to date that can substantiate such argument and quantify the difference between the two methods. This is mainly due to the difficulties and complexity to conduct such an experiment at high temperature over a long period of time. In this paper, the results from a recent investigation are presented. It describes the detailed procedures during the planning and execution stages, lessons learnt and pitfall to avoid. A scale inhibitor was aged using two different methods, one in bulk as commonly practiced in the industry and one inside a sandstone core. The aging period varied between 45 days as in the bulk and 110 days as for the last desorbed sample from the core. The samples which were aged inside the core retained much of their inhibition efficiency whilst that aged by the traditional method (bulk) lost nearly all its effectiveness. These results CLEARLY demonstrate that the conventional method of thermal aging in bulk is unrepresentative and that the loss in performance can be quantified. A NOVEL finding from this study is the evidences of an unexpected relationship between desorption and inhibition effectiveness. The findings from this study will have great impact on selecting chemicals for HT applications. More so in those environmental sensitive regions where the use of ‘yellow’ (biodegradable) squeeze chemicals are mandatory. Many of these have been discarded due to their apparent thermal degradation which is now proved to be unrepresentative.
Integrity Assessment of Well Barrier Threatened by Increasing Casing Hanger Loads
Authors: Okstad Eivind H. , Sangesland Sigbjørn 
Published: December 2007

Abstract
Degradations or interruptions of the original well barrier elements might occur at offshore wells after some time in operation. Experience from the Norwegian Continental Shelf has shown that these problems are not always treated as thoroughly as expected by the parties involved. This paper presents an approach for an efficient visualization and description of interrupted well barriers, basically to increase the well barrier control and management. By mapping the history of operational demands and load picture of the well in combination with the status of well barriers, a consistent basis for evaluations is obtained. The main intention is thus to realize the real well problem and its underlying causes in a controlled and systematic manner. Then, the responsible parties involved can take action more accurately according to the type of failure that has been revealed.
HazComWriter—Compliance Tool for MSHA Rule 30 CFR Part 47

or

OSHA Rule 29 CFR 1910.1200
Authors: Scott Douglas F. , Lecoq Paul E. 
Published: December 2007

Abstract
We are preparing to release a new tool to help companies write their required HazCom plan and list all hazardous chemicals at a company's site. Based in part on consumer input, we combined NIOSH's MSHA and OSHA versions of the HazCom Helper into one easy-to-use software tool. This tool, the HazComWriter, is more robust than its predecessors and features a sort utility, storage of the chemical list in an EXCEL format, and easy to use menus. The document produced by the HazComWriter will satisfy both MSHA and OSHA requirements for a "written hazardous communication document".
Optimal Waterflood Design Using the Adjoint Method
Authors: Kraaijevanger J. F. B. M. , Egberts P. J. P. , Valstar J. R. , Buurman H. W. 
Published: December 2007

Abstract
We address the problem how to operate the injectors and producers of an oil field so as to maximize the value of the field. Instead of agressively producing and injecting fluids at maximum rate aiming at large short term profits, we are after optimizing the total value (e.g. discounted oil volume) over the whole lifecycle of the field. An essential tool in tackling this optimization problem is the adjoint method from optimal control theory. Starting from a base case reservoir simulation run, this extremely efficient method makes it possible to compute the sensitivities of the total (lifecycle) value with respect to all (time-dependent) well control variables in one go, at a cost less than that of an extra reservoir simulation run. These sensitivities can be used in an optimization loop to iteratively improve well controls.
We implemented the adjoint method and an associated optimization algorithm in our in-house reservoir simulator. In addition to conventional well control options based on the well's pressure or total rate, we have also implemented smart well control options which allow the separate control of individual inflow intervals. Special adaptations of the optimization algorithm were required to allow the inclusion of inequality constraints on well control (pressure and rate constraints).
We applied the optimization algorithm to a number of cases, and found interesting, non-trivial solutions to some optimal waterflood design problems, that would not easily have been found otherwise.
In this paper, we also present a self-contained elementary derivation of the adjoint method, which is different from, but equivalent to the well-known derivation based on the Lagrange formalism.
ThermoChemical Process To Remove Sludge From Storage Tanks
Authors: Rocha Nelson O. , Khalil Carlos N. , Leite Lúcia C. F. , Goja Andre M. 
Published: December 2007

Abstract
The periodic cleaning of the bottom of crude oil storage tanks in vessels, terminals and refineries has become a big problem for industrial maintenance, principally due to the temporary inoperability of the equipment and the high environmental impact caused by the conventional treatments used. The storage of crude oil in large tanks invariably creates a gradual deposition process of organic sediments of high molecular weight.
PETROBRAS has developed a thermochemical method aimed at removing wax deposits in submersed oil pipelines, wax damage in production reservoirs and petroleum sludge removal from storage tanks.
This work presents the chemical treatment performed inside an oil storage tank located onboard an oil tanker as well as the laboratory methodology for the organic deposit physical-chemical characterization, kinetics of reaction, physical simulation, treatment dimensioning and operational treatment, aimed at the removal of 800 M3 of organic deposit.
The thermochemical method consists of a chemical reaction between two nitrogen salts that produce a strong exothermic chemical reaction. The heat produced by the reaction, together with the turbulence due to the generation of a large volume of nitrogen and the solvency, dispersed the initially solid compacted sludge at the bottom of the tank. The heat of the solution, estimated at 90°C, in contact with the sludge, irreversibly melted the organic fractions according to the previously studied phases diagram.
The method demonstrated itself to be efficient, safe and of low cost, when compared to existing classic methods. The process financial balance showed that the cost of the oil recovered from the organic deposit paid for the investment in chemical reagents and operational facilities.
One Year Experience With The Injection of Nitrate To Control Souring in Bonga Deepwater Development Offshore Nigeria
Authors: Kuijvenhoven Cor , Noirot Jean Christophe , Hubbard Paul , Oduola Lukman 
Published: December 2007

Abstract
The Bonga field, which is located in deep water off the Nigerian coast, started oil production at the end of 2005. In order to sustain production, seawater injection started from the beginning of the oil production at a rate of 300k bwpd. During the field development it was concluded that seawater injection in Bonga would result in reservoir souring, and that mitigation was necessary. Initially the selected strategy for Bonga seawater injection was to control reservoir souring with biocide and handle low levels of H2S with sour service materials and scavenging facilities topside. The maximum H2S the existing facilities could handle was set at 50 ppm (v).
The decision to control reservoir souring with biocide and handle H2S at surface was re-evaluated in 2003, and it was concluded that there would be a risk that the maximum allowable H2S content in the facilities (i.e. 50 ppm(v)) might be exceeded during the life time of the project. Given the positive experience with the injection of nitrate in other seawater floods throughout the industry, nitrate was selected as the mitigation method and injection started directly at the beginning of the waterflood at the end of 2005. As such Bonga is one of the first waterfloods where nitrate is being used to prevent reservoir souring, the main application so far has been to reduce H2S in already sour fields.
This paper presents the experience gained with the nitrate injection during the first period of the Bonga waterflood. Issues like logistics and how to ensure nitrate is applied correctly are discussed in more detail. In addition laboratory testing executed to define an appropriate nitrate injection rate under Bonga conditions are also presented.
After several months of operation the Minox unit to remove the bulk of the oxygen broke down and oxygen control was done with chemical oxygen scavenger only. With this different mode of operation, the effectiveness of the nitrate as souring mitigation method was expected to be affected. Additional laboratory experiments, also reported in this paper, were performed and did not indicate any issue with respect to the predicted souring.
Assessing Multiple Resolution Scales in History Matching With Metamodels
Authors: Rodriguez Adolfo A. , Klie Hector , Wheeler Mary F. , Banchs Rafael 
Published: December 2007

Abstract
In this paper we present a new multiscale approach to history matching assisted by a neural network metamodel. The method starts with the construction of a fine scale a priori model that includes geological and geostatistical information. We then apply a singular value decomposition (SVD) in order to obtain a parametric representation of the permeability field, in a way that a fixed set of eigenimages are determined with the parameters to be inverted as weights in the expansion. Through this procedure not only is the number of parameters significantly reduced, but also the weights in the SVD expansion define a hierarchy that naturally separates the different resolution scales in the system. We show that the multiscale procedure alone helps to significantly reduce the CPU time required to accomplish the parameter estimation. Furthermore, the reduced parameter space facilitated the training of the neural network engine.