bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Case Study of High Pressure Brine Flows within the Zechstein Supergroup of the Southern North Sea
Authors: Finnie A. B. 
Published: December 2007

Abstract
This paper presents the case histories of four adjacent development wells drilled through the Zechstein formations in the Southern North Sea (SNS) during ‘99-‘00. A jack-up MODU was used in cantilever mode. Formation pressures encountered ranged from 18.1ppg to 19.25ppg EMW. Brine kicks, believed to be among the most intense in the SNS, were experienced. Of the 4 wells, 2 encountered high-pressure from Plattendolomit formation, while the other two experienced significant pressures from within the Zechstein salt itself.
The Zechstein Supergroup is a series of evaporite and carbonate formations formed ca. 250 million years ago1. It has presented Southern North Sea drillers with significant problems since drilling began ca. 1965. This paper focuses on the problems associated with the drilling of the Z3 series. These are overpressure; losses; and loss/gain situations. A description of each problem and the industry’s current thinking towards them is presented. The recent wells have provided a learning opportunity. The prospect of encountering high-pressure was considered likely. Contingency plans were drawn up and implemented in response to events. The experience gained, as the project progressed, was used to tailor the approach towards the subsequent wells. This iterative process is followed, as each well is drilled, and serves to provide a variety of learning points. These are categorised as 1) Wells Problems and Solutions 2) Practical Problems and Solutions. These cover issues ranging from how to circulate kill mud effectively to determining the volume of influx. The learning is documented and presented as a reference for future developments.
New Operator Achieves Best in Class Performance in CNS
Authors: Redgrave S. , Kipperman E. , Morton T. R. 
Published: December 2007

Abstract
During April – June 2000, Veba Oil & Gas UK Limited (VOGUK) drilled three Appraisal wells in the Guillemot West/Western Extension as Sole Risk (no partners) Development Pilot holes. The wells were designed as "keeper wells" that could be used as Development wells if successful.
The wells were drilled under high angle, with 13 3/8" casing set at 70 degrees inclination in water based mud, penetrating the reservoir in 12 ¼". During the drilling of the 12 ¼" hole section, synthetic based mud cuttings were collected and, using skip-andship operations transported for disposal on land. Inside drill pipe gyro runs were required to open up tight targets, and novel TLC (Tough Logging Conditions) tool combinations were run under high over balance conditions, achieving all objectives.
The paper describes the "can-do" approach for this successful fast track project (5½ months from start of planning to end of drilling). The paper covers the consultations with the Government bodies, the environmental issues solved, the contracting process, procurement of materials, the new technical applications and the Team-approach used to achieve the Best-in-Class drilling performance.
A Mathematical Algorithm for Modeling Geomechanical Rock Properties of the Khuff and Pre-Khuff Reservoirs in Ghawar Field
Authors: Al-Qahtani Mohammed Y. , Zillur Rahim 
Published: December 2007

Abstract
The Khuff and Pre-Khuff are deep gas condensate reservoirs under active tectonic stress environment. The reservoirs are under development using horizontal wells and vertical wells with hydraulic fracturing. Modeling geomechanical rock properties accurately is essential for ensuring a successful frac job design and execution. During the last two years, a large amount of additional lab and field information has become available. Integration of all the data was conducted for better estimation of in-situ geomechanical rock properties.
This paper presents the results of a mathematical algorithm for calculating the geomechanical rock properties for the Khuff and Pre-Khuff reservoirs in the Ghawar field. The model is derived from the classical poroelastic model in addition to a tectonic strain component as proposed by Prats and Warpinski. The model was calibrated to lab data as well as to the results of several Microfrac and Minifrac field tests. The model was further improved by calibrating it with actual history-matched frac data.
The algorithm describes a methodology for systematically calculating geomechanical rock properties and in-situ minimum horizontal stress magnitude from sonic shear and compression log data. The paper also describes a detailed history-matching algorithm for Minifrac and frac data using a 3-D frac simulator. The results show that the minimum in-situ stress in the Khuff and Pre-Khuff reservoirs is governed by the tectonic effect, which is Young’s modulus dependent. Detailed analysis and well examples are presented.
Considerations on the Selection of an Optimum Vertical Multiphase Pressure Drop Prediction Model for Oil Wells
Authors: Takacs Gabor 
Published: December 2007

Abstract
First, the paper gives a classification of the calculation models commonly used for the calculation of multiphase vertical pressure drops in oil wells. The main parameters of the experimental data used to develop the different empirical correlations are presented indicating the ranges where the correlations are expected to perform best. Next, an analysis and classification of the many possible causes of calculation error is given. Deviation of calculated and measured pressure drops is shown to stem from different sources that can have different importance from case to case.
The author collected and summarizes in the paper the findings of the many previously published investigations on the accuracy of the different pressure drop calculation models. A table including all available data on calculation accuracies is also presented. Statistical parameters of these investigations are shown to be widely scattered and to be of limited use to engineers seeking the most accurate model. Differences and contradictions in the results are evaluated and explained.
Finally, the author describes the petroleum engineer's proper attitude towards vertical pressure drop correlations. Practical implications of the proposed philosophy are also detailed. In conclusion, the paper provides the required insight and proper attitude to petroleum engineers facing the problem of predicting multiphase pressure drops in oil wells.
Optimizing Acid Treatments With the Use of Jet Blasting Tool
Authors: Dahroug Ahmed , Brown Barry , Shaheen Mansour 
Published: December 2007

Abstract
Coiled Tubing is a common method of diverting treatment fluids into wellbore formations in open hole and cased hole completions. The efficiency of the treatment can be significantly improved by increasing the impact force of the fluid on the formation.
The recently developed JetBlaster™ Tool has been used on some cases as the optimum BHA that can be used with Coiled Tubing for the efficient delivery of treatment fluids. The software JetADVISOR supports system hydraulic analysis and the design of the tool configuration in terms of nozzle and orifice diameter. This allows optimization of jet impact force or hydraulic horsepower, and ensures a sufficiently high rotational speed to effectively divert the treatment around the circumference of the wellbore. The addition of velocity increases the affectivity of the treatment.
In order to assist evaluation of the efficiency of the technique we have primarily attempted to treat a well that had formation drilling damage with the tool while pumping a non corrosive fluid that has no direct chemical reaction with the formation filter cake. The well was then put on the test to see the increase in production and wellhead pressure and the results recorded and compared. Then the same treatment was repeated but while jetting acid, then the well was once again put on test.
Coiled-Tubing-Conveyed Hydromechanical Pipe Cutting: A Safe, Effective Alternative to Chemical and Explosive Severing Methods
Authors: Fanguy Dean J. 
Published: December 2007

Abstract
In the past, tubing, casing and drill pipe recovery has been employed where chemical and explosive severing tools could not effectively sever the pipe.
A coiled-tubing-conveyed hydromechanical pipe cutting system has proven to be a viable alternative to pipe recovery when conventional severing systems are not effective. The system does not contain or require any hazardous materials, which makes it safer to use than conventional systems.
The pipe cutting system incorporates modular stabilizing devices that decrease the risk of the coiled tubing forces and the wellbore deviation from interfering with the cutting operation. The pipe-cutting mechanism uses several unique blade configurations that were designed specifically to address various metallurgical properties and dimensions. The cutting blades contain state-of-the-art cutting inserts, which were previously proved in various metal milling and cutting applications within subterranean wells.
A detailed description of the coiled-tubing-conveyed hydromechanical pipe cutting system, its operational function and a variety of case histories are discussed in this paper.
An Experimental Study of Drag Reduction of Polymer Solutions in Coiled Tubing
Authors: Shah Subhash N. , Zhou Y. 
Published: December 2007

Abstract
The excessive friction pressure loss due to the small tubing diameter and the curvature (which believed to cause secondary flow) of coiled tubing (CT) often limits the maximum obtainable flow rate in CT operations. This paper presents an experimental study of drag reduction performance of several polymer solutions in coiled tubing using a sophisticated full-scale coiled tubing test facility for an industry-university joint research project. The facility includes of seven reels of coiled tubing with diameters of 1", 1-1/2", and 2-3/8", fluid mixing and pumping equipment, and data acquisition system. Fluids investigated include water and solutions of polymers currently used in the well drilling and completion industry – Xanthan gum, partially hydrolyzed polyacrylamide (PHPA), guar gum, and hydroxyethylcellulose (HEC). Experimental results showed that the amount of friction drag reduction differs significantly among the different types of polymers at various concentrations. Data interpretation and analysis revealed that the CT diameter and the CT-to-reel drum diameter ratio are important geometrical parameters affecting drag reduction. The flow data indicate that the onset of turbulent flow in CT is suppressed in the polymer solutions. This paper introduces the concept of the modified drag reduction envelope for flow of polymer solutions in coiled tubing.
Selection of Optimum Coiled-Tubing Drilling Parameters Through the Cuttings-Bed Characterization
Authors: Cho Hyun , Shah Subhash N. , Osisanya Samuel O. 
Published: December 2007

Abstract
The effects of cuttings bed at intermediate deviation of wellbore (30 – 60°) from vertical are quite complicated in cuttings transport because the movement of cuttings bed with its direction has not been well understood. The effect of cuttings bed movement in this region has also been neglected in most other mathematical models. The reason for this might be the instability of cuttings bed. This study shows that neglecting the cuttings bed characteristics may result in improper selection of coiled tubing drilling parameters, which may frequently lead to costly problems such as stuck pipe. However, the existing models, which can handle from vertical to horizontal wells with only a function of the wellbore deviation, cannot properly characterize the effects of cuttings bed movement in cuttings transport mechanism for the intermediate deviation of wellbores.
A mathematical model is proposed based on momentum and force balances in this region. All parameters, which involve cuttings bed movement and its direction, build up and erosion of cuttings bed, and wellbore deviation, are analyzed quantitatively. The analysis of the data obtained from the simulation allows interpretation of the relationship between major parameters affecting characterization of the cuttings bed in this region. The concept of minimum anti-sliding velocity of cuttings bed (MASV) is developed based on the interrelationship between parameters, which involves fluid rheology, wellbore deviation angle, interfacial friction between suspension layer and cuttings bed, and in-situ fluid velocity in suspension layer. This study also provides the selection guide of drilling parameters affecting wellbore cleaning by a compromise process for optimum combination of the parameters.
Reserve Overbooking – The Problem No One Wants to Talk About
Authors: McLane M. A. , Rose P. R. 
Published: December 2007

Abstract
Managers of publicly held companies often face pressures that can tempt even the most principled to push the envelope of credibility in efforts to buoy investor confidence and thus increase stock value. In an age of instant gratification and inflated expectations of return on equity, companies often struggle with long range strategic planning while at the same time striving to meet expectations of the next quarterly earnings report. The quest for increased market capitalization often leads these harried managers to look under every stone for anything that will entice more investors to buy into their company.
The assets of oil and gas companies consist mostly of hydrocarbons in the ground – reserves. In typical annual reports one often finds proved oil and gas reserves stated in very precise terms. These reserve numbers are, in reality, very imprecise because of the variability and uncertainty in the earth and in the industrial and economic world. This is why the industry is moving increasingly away from deterministic reserve estimates to probabilistic, or stochastic, reserve estimates. Ironically, it is the very uncertainty associated with reserves that has enabled and preserved a practice that has, over the last twenty years, destroyed value and led many investors down the primrose path – reserve overbooking.
Reserve overbooking occurs for many reasons, among them poor estimating practices, misguided incentives, ignorance, competition for investors, and lack of professionalism. Any temporary benefits companies may derive from overstating reserves disappear whenever reserves must be de-booked. The resulting loss of confidence by investors and analysts is often made more painful by the fact that it could have been avoided. Reserve overbooking is a problem that may be solved through consistent, professional reserve estimating and reporting, and leadership, professionalism and accountability by informed and knowledgeable managers.
Problems Reconciling Probabilistic and Deterministic Reserve Classifications and Evaluations
Authors: Purvis Dwayne C. , Strickland Richard F. 
Published: December 2007

Abstract
The current SPE/WPC definitions for reserves quantified by probabilistic methods are ambiguous and largely inconsistent with deterministic criteria. Probabilities are least well defined and most subjective at the extremes of the ranges of outcomes. Since reserve definitions are meant to provide consistency across evaluators and evaluations, the current definitions are not workable. When defining reserves, volumes should first be classified into a category. A probabilistic analysis can then be made of the uncertainty in each category, and a central estimate of Proved reported. When probabilistic analyses are used to determine value, the same restraints are not necessary, but the same wariness of the extremes of the distributions should be applied.
A New Tool to Make Quick Estimates of Probabilistic Reserves from Production Trends
Authors: Idrobo E. A. , Jiménez E. A. , Bernal M. C. 
Published: December 2007

Abstract
The estimation of probabilistic distribution of reserves is increasingly being used in the oil industry. However, this is not an easy assignment because of the amount of information required and costs associated. Even more complicated is the task of evaluating distribution of reserves departing from production trends. The historic analysis of production has usually used a deterministic approach in the form of Decline Curve Analysis (DCA).
In this paper we present a quick and efficient application for estimating probabilistic distribution of reserves combining the usually available production information with the power of stochastic methods through the use of decline curve analysis: PREP (Probabilistic Reserves Estimation Package). The computational tool developed uses a Monte Carlo-type technique under an efficient optimization algorithm to calculate the DCA parameters. More than 200 realizations can be generated and evaluated in a few seconds for diverse production scenarios and information such as standard errors, confidence intervals, expectation curves can be visualized to uncertainty diagnosis.
We have applied the proposed tool on several fields located in the Valle Superior del Magdalena Basin in Colombia, South America. The Valle Superior del Magdalena Basin is estimated to contain over 1,400 million barrels of oil-in-place of which only 14.7% have been produced. The results obtained have had strong economic impact on reservoir management decisions.
Seismically Derived Variation of Heterogeneity Factor-Application in Estimation of Production Rate and Porosity Variation within the Reservoir
Authors: Mohanty S. N. , Krishna B. R. 
Published: December 2007

Abstract
In heterogeneous reservoirs rate of production of hydrocarbon vary significantly between the wells. Estimation of flow rates prior to drilling is very important in formulating development scheme. Any change in petrophysical properties of a reservoir is reflected in variation of heterogeneity. Quantification of variation of heterogeneity will help in predicting the reservoir performance and production of hydrocarbons. This paper outlines a method for deriving heterogeneity gradient using seismic data and its application in predicting the performance and porosity of unexploited part of the Narimanam field in Cauvery Basin, Southern India.
Legislative Trends in Environmental Regulations Impacting the Petroleum Industry
Authors: Sandosham A. S. , Lim Doris M. F. 
Published: December 2007

Abstract
Emerging changes in environmental regulations in many Asian countries will significantly impact the petroleum industry. These changes include the implementation of more effective ambient air quality monitoring programs in many Asian countries, tightening of point source emission standards, and programs directed at vehicular emissions including changes to fuel specifications. This paper presents the current ambient air quality standards in selected Asian countries and highlights upcoming regulatory trends that will impact the industry. Case studies are presented for Hong Kong and the Philippines to demonstrate how these changes will be implemented in the next five years.
Vehicles are the largest contributor to urban air pollution. Hence, many regulatory programs focus on reducing vehicle emissions to improve air quality. Significant changes to fuel specifications, including the impact of region-wide reductions in fuel sulfur and benzene contents will be discussed. These changes will impact the petroleum industry, particularly in the refining sector. Measures that have been implemented to control vehicular emissions include the conversion of public transport vehicles to Liquified Petroleum Gas (LPG). As LPG and liquefied natural gas (LNG) usage increases, particularly due to environmental considerations, strategic changes will be required in the petroleum industry to profitably manage this transition.
Analysis of a Non-Volumetric Gas-Condensate Reservoir
Authors: Vega L. , Barrufet M. A. 
Published: December 2007

Abstract
Predicting water encroachment can be of critical importance in describing and managing a hydrocarbon reservoir.
This study focuses on the use of the generalized material balance equation (GMBE) proposed by Walsh, et al1,2 along with the analytical solution to the diffusivity equation for a constant inner boundary pressure as presented by van Everdingen and Hurst to determine the size of a water-bearing formation in contact with a gas-condensate reservoir.
When the hydrocarbon reservoir fluid is a gas-condensate, it is essential to use the GMBE. Should the conventional material balance equation (CMBE) be used in lieu of the GMBE, considerable errors could be introduced as will be shown.
The main goal of this paper is to illustrate the ability of the GMBE to determine the size of an aquifer encroaching into a gas-condensate reservoir. Once this size is obtained, it could be used as an input parameter to a reservoir simulator to forecast the future expansion of the aquifer as depletion proceeds.
When the CMBE is used to describe black oil reservoirs, certain simplifying assumptions are normally made. Those include neglecting the effect of the compressibilities of the connate water and the reservoir rock, in addition to the volatilized liquid in the gas phase. The effect of these assumptions in gas-condensate reservoirs will be examined.
Testing of Gas Condensate Reservoirs - Sampling, Test Design and Analysis
Authors: Kool Henk , Azari Mehdi , Soliman M. Y. , Proett Mark A. , Irani Cyrus A. , Dybdahl Bjørn 
Published: December 2007

Abstract
Testing of gas condensate reservoirs requires careful coordination of all parameters in the analytical process. Therefore, the sampling procedure, the laboratory analysis of the collected samples, the design of the testing equipment, and the design and analysis of the test itself are all critical to the accuracy of the analysis. This paper will outline the methodology and procedures used in testing gas condensate reservoirs.
Obtaining a representative formation fluid sample that may be used for compositional and pressure-volume-temperature (PVT) analysis is crucial in testing gas condensate reservoirs. In most cases, this means maintaining a monophasic sample as close as possible to actual reservoir conditions. New sampling technologies have been introduced that improve the quality of the initial sample and can maintain the sample integrity. Additionally, new downhole sensor technologies show promise of improving sample contamination estimates and making in-situ fluid property measurements. The various sampling techniques are discussed, and comparisons of processes that include wireline formation testing and bottomhole sampling, isokinetic sampling used in drillstem and production testing, and surface sampling are made.
Laboratory testing procedures including sample quality validation, error propagation, and sample contamination are also discussed.
The flow of gas condensate in a reservoir is a complicated mathematical problem involving phase changes, condensate loss into the small pores of the rock, multi-phase-flow of the wet gas oil and possibly water, phase redistribution in and around the wellbore, and finally, liquid vaporization back into the condensate gas. A well test can provide identification of the absolute reservoir and relative permeabilities, the source of declining gas permeability, near wellbore damage, and the reservoir pressure. It can also distinguish the extent of the liquid-condensate bank that forms a composite reservoir, as well as the location of the nearby boundaries.
The analysis procedure and techniques will be illustrated through presentation of two field cases. In the first case, the flowing pressure is above the dewpoint pressure. Thus, the fluid inside the reservoir is a single-phase gas, and liquid dropout causes phase segregation in the wellbore. In the second case, the well is producing below the dewpoint pressure while the original reservoir pressure is above the dewpoint pressure. This caused the well test to resemble that of a composite reservoir with earlier phase-segregation effects.