bluuebunny/crossref_metadata_2025 huggingface dataset:
Zirconium Citrate: A New Generation Dispersant for Environmentally Friendly Drilling Fluids
Authors: Nicora Luigi F. , Burrafato Giovanni
Published: December 2007

Despite their already widespread and successful use in several industrial branches, zirconium compounds are underexploited in the drilling industry and have a great potential for more applications1.

An innovative product based on zirconium citrate can control high temperature gelation of bentonite at temperature exceeding 400°F or increase the temperature stability of all kinds of lignites and lignosulfonates in dispersed muds. In polymer muds the use of this compound can strongly reduce the need for mud dilution by controlling unwanted increases in mud viscosity and is an effective means for stabilizing rheology during stopped circulation. This biodegradable and non toxic product looks promising as a replacement for potassium dichromate and Cr-lignosulfonates in high temperature applications. Laboratory studies and field experiences are described in this paper, together with ecotoxicity data.
Turbo Drilling Through Coiled Tubing Using Foam In Sub-hydrostatic Well : A Case History For Jotana Field In Cambay Basin, India
Authors: Kumar Manoj , Jain P.C. , Srivastava A.K. , Johari Anil
Published: December 2007

Several sub-hydrostatic wells have the problem of declining production due to build up of consolidation of produced sand fill and heavy scale deposits in the 5" or 7" casing. Conventional Coil Tubing Operation using high pressure jetting failed to clear the hard deposits. To meet this challenge innovative idea of Foam TURBO DRILLING with Coil Tubing was successfully carried out for the first time in oil fields of India. In the process 70% foam was used with suitable compatibility with the lithofacies encountered in Jotana field in the Cambay Basin. Suitable commercially available drill bit with P.D. motors was used to drill the deposits with the help of foam. A successful operation resulting in incremental production from Sub-hydrostatic well.

P. 365
The Use of QRA Technology in Drilling and Well Operations
Authors: Lewis D. B. , Brand P. R. , Maes M. A.
Published: December 2007

The use of a reliability based design philosophy relative to Oil County Tubular Goods is becoming more important as operators continue to push the limits of materials and equipment by driving than into ever environments and ever more unusual operating scenarios. The use of allowable or working stress design no longer serves the designer in these unusual situations. The means of determining the risk or reliability of the operating scenario is critical, from a safety viewpoint as well as from an optimized design viewpoint.

Quantitative Risk Analysis (QRA) provides the necessary tool for the optimization of a design while quantifying the associated risk of the design for a particular scenario. QRA can and does go beyond the conventional load combinations and standard operations. It is a powerful tool for allowing the operator to "put the pieces together differently".

In this paper, the QRA technology is discussed not only for design but analyzing problems and scenarios which is not the norm. It discusses how the technology can be applied on out of the ordinary operations and how these operations which are considered by the Industiy as unacceptable or unsafe can be achievable if one knows what the risk is and what is driving that risk.

Although QRA and total system reliability / assessment is in its infancy in drilling and well operations, in the years to come it will become one of the prominent technologies of the Oil and Gas Industry.
A Reliability Approach to the Design of OCTG Tubulars Against Collapse
Authors: Ju G.T. , Power T.L. , Tallin A.G.
Published: December 2007

This paper was prepared for presentation at the SPE Applied Technology Workshop on Risk Based Design of Well Casing and Tubing held in The Woodlands, Texas, U.S.A., 7–8 May 1998.
A System for Comprehensive Measurements of Pipe Wall Thickness and Diameter in Support of Risk-Based Tubulars Design
Authors: Aldin M. H. , Logan K. , Burres C. V. , McGill R. M.
Published: December 2007

In risk-based design of well casing and tubing, part of the calculations for burst and collapse reliability depend on the statistical distribution of the pipe wall thickness and ovality properties. It is not sufficient to have random or local (point-wise) readings of these parameters. Instead, the calculations must account for the actual minimum and average values as they occur statistically along each entire joint of pipe. This paper explains the methodology and results from the development of a data acquisition system designed to acquire and report comprehensive pipe wall and diameter measurements as part of the standard pipe inspection process.

An online data acquisition system with six analog input channels was developed to acquire and store wall and diameter data for tubulars with diameters between 4.5 in. and 20.0 in. This system was designed so that it would neither interfere with nor add any cost to the existing inspection process at ICO. The wall thickness measurement is incorporated into already existing ultrasonic inspection equipment. The system yields 600 wall readings per pipe revolution. With a typical advancement speed of 1.375 revolutions per inch of travel, this translates into over 160,000 wall readings per typical joint of pipe. Software, covered in this paper, processes and reduces this data to minimum and average wall values on a per-joint basis.

The diameter measurements are obtained from collimated light sources, which cast shadows onto optical sensing arrays. The pipe diameter is determined by the fraction of array elements not receiving light. This system also yields 160,000 readings per typical joint of pipe. Noise and inconsequential ovalities (ovalities over lengths less than 6 diameters) are removed, yielding a maximum and minimum ovality for each joint.
A Computationally Efficient Iterative Solver for Reservoir Models with Faults/Pinchouts
Authors: Chien Mark C.H. , Chun Dong H.
Published: December 2007

An incomplete Gaussian elimination of a reduced system (RS) is one of the most efficient preconditioners of an iterative linear solver for reservoir simulation models. The reduced system is formed from eliminating half the unknowns from problems whose matrices have regular red-black ordering. This precludes the application of the RS method to reservoir simulation models with faults and pinchouts, which incur irregular connections. This paper extends the method to solve Jacobian matrix generated from such a reservoir simulation model. A generalized minimum residual method is used to accelerate the solution.

P. 649
Seizing the Environmental High Road
Authors: Ebenhack Ben W.
Published: December 2007

In popular perception, fossil fuels are cast as nemeses of the environment. This sets up a false choice that traps too many of us, even in an industry well situated to know better and to say so. For us, this too often means accepting an adversarial role. We could instead take the high road.

In the real world, energy alternatives do not represent a dualistic either/or choice, but mixes of kinds of energy, used in particular times and places and under particular economic and technologic conditions. Lift the shroud of misconception and the real choices can be seen.

Renewability is often construed as an environmental benefit in and of itself, as well as an absolute characteristic of the commonly discussed "energy alternatives." This is not true. Similarly, talk of a "closed carbon cycle" for biomass fuels is critically flawed in the way it defines boundary conditions. If we further expose the flawed assumptions underlying the extrapolation of trends which overestimate the near term potential of popular energy alternatives, we can engage issues of energy for the future constructively.

Industry members gain nothing by denying the fundamental importance of the environment or the costs attributable to energy consumption. We gain something important by shifting the public debate away from false choices and to the real ones. In many lower income countries, for example, fossil fuel development can provide an environmental benefit, and the environmental costs of not using fossil fuels can be seen with particular clarity.

As we see and formulate the issues more clearly, we in the energy-producing industry can take a proactive stance in the evolution of energy mixes optimized for the context of time, space, environment, and economy.

P. 667
A Model to Predict Wireline Formation Tester Sample Contamination
Authors: Akram A.H. , Fitzpatrick A.J. , Halford F.R.
Published: December 2007

Wireline formation testers (WFT) collect fluid samples for PVT analysis through a probe set against the borehole wall. Filtrate contamination is reduced prior to sampling by either pumping the mixture of filtrate and reservoir fluid from the formation to the borehole or flowing the mixture into one or more WFT chambers. The cleanup is monitored at the surface. The time to reach the level of acceptable contamination (LAC) depends on the depth of invasion, pumpout rate and various fluid and rock properties.

Generalized guidelines predict time to first oil based on simple volumetrics but do not predict the rate of cleanup. Excessive cleanup time increases costs and the risk of differential sticking of the tool/cable. In some cases it may not be practical to attempt the operation as the LAC may take too long to achieve.

A numerical simulator was used to investigate the characteristics of the contamination level versus time curve and to define the variables governing cleanup.

The model was validated using data from five wells from two fields with differing rock and fluid properties. One hundred and fifty simulation runs were made with different invasion depths, flow rates, and rock and fluid properties.

An equation was developed for field use, that estimates filtrate contamination fw as a function of cleanout time t.

An alternative approach for WFT sampling is also suggested, using not one but two probes. With this method, both cleanup time and the final level of filtrate contamination can be substantially reduced.

P. 27
Formation Testers vs. DST - The Cost Effective Use of Transient Analysis to Get Reservoir Parameters
Authors: Frimann-Dahl C. , Irvine-Fortescue J. , Rokke E. , Vik S. , Wahl O.
Published: December 2007

The use of formation testers to get vertical pressure profiles, mobilities, in-situ fluid samples and vertical permeabilities is well known in the industry. Several tools are designed with multiple sample chambers and multiple probes to achieve the above objectives. In Norsk Hydro, there has been limited use of the mobility, k/μ, typically because this is a measurement in the "damaged zone". This measurement is also influenced by mud filtrate and is assumed normally to represent a too low value of permeability. The aim has therefore been to get a pressure transient that extends past the damaged zone and into virgin rock and fluid for a good permeability estimation. Data collected from the North Sea, using a single probe in open hole, proves radial flow after only short durations. Typically, a drawdown and buildup sequence lasts for one hour or less, and radii of investigations have been proven up to 90 meters. Permeabilities in good agreement with the average of core plugs over the same interval were obtained. Also, examples of pressure transients from several intervals in a low permeability turbidite sand will be shown to exhibit outer boundary effects at only short radii of investigations. In the examples shown, the welltests (DST) were cancelled because the objectives were met using the formation tester (FT).
Multi-resolution Analysis of Long-Term Pressure Transient Data Using Wavelet Methods
Authors: Kikani Jitendra , He Meiqing
Published: December 2007

Large bandwidth transmission systems have made it easier and convenient to routinely collect large data from permanent monitoring systems. To effectively manage, filter, reduce and interpret these large data sets requires sophistication and methodologies that have sound bases. The standard data reduction procedures are fraught with difficulties and have biased modes which give rise to aliasing effects. In fact, a two step process is recommended wherein noise filtering and behavioral filtering are separated and allowance is made for visualizing the data at different dyadic scales of resolution.

In this paper, the characteristics of simulated pressure transient data are investigated in the frequency domain. The power spectrum properties of both simulated data (with random noise added) and real data sets are studied. Wavelet transform is introduced to accomplish the time-frequency analysis of long- term pressure transient data. The characteristics of different family of bases of wavelets are studied, and a recommendation is made for use with pressure data. Application of wavelet transform in data denoising has been experimented with and the performance of different thresholds established. Two types of denoising methods are recommended for slowly changing pressure transient data. Multi-resolution approximation of the long-term pressure transient data using wavelet transform is also presented. Approaches for data culling are addressed.

P. 117
Integrating Pressure and Fractional Flow Data in Reservoir Modeling With Fast Streamline-Based Inverse Method
Authors: Wen Xian-Huan , Deutsch Clayton V. , Cullick A.S.
Published: December 2007

Generation of a reservoir model's spatial permeability distribution directly from historical multiple-well pressure and fractional flow rate data requires an inverse solution of the flow equations. This computation generally utilizes a gradient method to solve the minimization problem. A previously reported geostatistically-based inverse sequential self-calibration (S SC) technique has been shown to significantly reduce the computer time as compared to full inversion solutions and to yield excellent results for single-phase pressure.

In this paper we extend the SSC to jointly invert multiple well pressure and multiphase fractional flow data by:adapting a fast streamline simulator for the forward flow solution; andimplementing a new method for computing the sensitivity coefficients for fractional flow rate.

The method is fast and robust, and an important consequence of the method is that the spatial correlation structure is honored through the kriging equations in the SSC. This leads to well-behaved objective functions with low final values and preserves the prior model spatial characteristics.

The paper demonstrates the extended SSC for generating permeability realizations from production data using a synthetic reservoir model. The paper systematically compares the quality of the production data matches for inversion of pressure data alone, fractional flow rate data alone, and the combination of fractional flow rate and pressure data. For the synthetic model, pressure data alone provides coarse information primarily near the wells, whereas the fractional flow data provide more information on interwell spatial reservoir permeability. Inverting pressure and fractional flow data jointly lead to significant improvement of the representation of reservoir heterogeneity and reduction in uncertainty. The paper shows that the accuracy of reservoir performance predictions at wells can be dramatically improved by building the models using the historical production data from those wells. However, if only production data have been used to build a model, the results also indicate that the prediction capability may be limited for new wells drilled in areas outside the influence region of existing wells or under flow or well conditions different from those used for the inversion. Future research directions are discussed at the end.

P. 161
Advancing Horizontal Well Sand Control Technology: An OHGP Using Synthetic OBM
Authors: Gilchrist J.M. , Sutton L.W. , Elliott F.J.
Published: December 2007

This paper describes a Gulf of Mexico case history that successfully demonstrates a horizontal well can be drilled with synthetic oil based mud (SOBM), and gravel packed with aqueous fluids while still offering excellent well productivity and sand control integrity. The result significantly expands the application of open hole gravel packs to encompass a range of reservoir types and well trajectories thought to date to be unachievable.

Key aspects of delivering this technology are discussed in this paper: what major technical risks were identified, how these were managed through an intensive laboratory testing program, engineering, global resourcing, and teamwork put into this project.

In particular the following key achievements will be discussed in detail: the successful horizontal balanced displacement from SOBM to kill weight brine, back production of barite laden SOBM filter cake through the gravel pack with minimal productivity impairment, and some important data acquisition results designed to increase our insight into this well type.

P. 121
Harding A Field Case Study : Sand Control Strategy for Ultra High Productivity and Injectivity Wells
Authors: McKay G. , Bennett C. , Price-Smith C. , McLellan W.
Published: December 2007

The Harding field is the first horizontal well development by BP and partner's in the highly unconsolidated Balder Massive Sand. The field development utilizes a TPG 500 Jack-up Drilling and Production Unit in conjunction with a concrete Gravity Base Tank (GBT) providing oil storage of 500,000bbls (see Figure 1.0). A combination of the highly permeable, unconsolidated formation with active water/gas drives and viscous oil creates a high coning potential. This means that achieving and maintaining sand free production through optimal completion design was critical to the overall success of the development.

The first Phase of horizontal wells were drilled and completed for sand free, ultra-high rate production (>30,000 BOPD/well, with PIs in excess of 1000 bbl/day/psi). High rate Water Injectors are required for vital voidage replacement and pressure support. Initial injection water requirements were provided by 2 dedicated Aquifer source wells.

This paper describes the strategy adopted and the factors considered in the development of the sandface completion design for Phase 1 of field life. The experience gained on Phase 1 have contributed to the design enhancements required for the more complex and challenging aspects of Phase II, which will include extended reach horizontal wells to neighboring satellite pools. These enhancements have been engineered taking into account the variations in reservoir quality, physical installation challenges and production profile requirements, in order to achieve continuing longevity and the high well PIs/IIs synonymous with the Harding Development.
Interaction Between Shale and Water-Based Drilling Fluids: Laboratory Exposure Tests Give New Insight Into Mechanisms and Field Consequences of KCl Contents
Authors: Horsrud P. , Bostrom B. , Sonstebo E.F. , Holt R.M.
Published: December 2007

To predict and cure borehole instabilities during drilling, it is important to have a profound understanding of the effects that the drilling fluid (in particular water-based muds) may have on shale behaviour. This paper focuses on the consequences of KCl exposure on smectite-rich shales. These effects have been studied by various experimental techniques, both under atmospheric and simulated downhole conditions. This has identified several particular effects as a consequence of potassium intruding the shale. One effect is that the shale shrinks, primarily due to cation exchange. This process increases the permeability and changes the deformability and possibly also the strength of the shale. Simulations of the shrinkage effect around a borehole show that the compressive stresses will decrease with increasing KCl concentration, and this improves the stability. Tensile stresses may eventually be generated in the formation at high concentrations. This enhances the possibility of borehole instability problems and also increases the rate of potentially damaging effects (pore pressure diffusion, ion transport). An important conclusion is that an optimum KCl concentration appears to exist.

Shale-fluid interactions were found to depend strongly on the test methods and procedures, calling for a careful review of methods used for optimum drill fluid design. The testing also revealed that the effect of potassium is fundamentally different from other cations upon exposure to shale.

P. 215
Compositional Simulation of Asphaltene Deposition and Plugging
Authors: Nghiem Long X. , Coombe Dennis A. , Ali S.M. Farouq
Published: December 2007

This paper describes the incorporation of an asphaltene deposition and plugging model in an Equation-of-State (EOS) compositional simulator. The precipitated asphaltene is represented as a pure solid. It is shown that this representation provides an efficient and satisfactory method for modelling the phase behavior of asphaltene, in both gas injection and pressure depletion processes. The precipitated asphaltene can deposit onto the rock surface through an adsorption process, or flow as a suspended solid in the oil phase. Compositional simulation of a typical gas injection core displacement and of a radial single-well primary depletion show that important phenomena and observations reported in the literature were reproduced adequately.

P. 129
The Impact of Formation Damage and Completion Impairment on Horizontal Well Productivity
Authors: Burton Robert C. , Hodge Richard M.
Published: December 2007

Horizontal, openhole completions, especially completions incorporating sand control, are prone to productivity impairment from a variety of sources. Often, the potential productivity of these wells is not achieved and in some cases, production is severely limited. This paper examines common sources of formation and completion damage that can lead to significant productivity impairment in horizontal, openhole completions and discusses techniques to overcome these problems.

A process to design horizontal wells for maximum productivity has been applied in a variety of locations including the North Sea, Gulf of Mexico, and the Far East. First, laboratory testing of drill-in fluids (DIF), sand control screens designs, and clean-up treatments is conducted under simulated downhole conditions. These results are used in an analytical model to predict horizontal well productivity. This modeling verifies critical well design features and assists in identifying drilling/completion products and techniques that minimize productivity impairment.

These studies show that a comprehensive testing, design, and evaluation protocol can be used to maximize horizontal well productivity and identify products and practices that cause productivity impairment. The modeling results and field cases illustrate the necessity of evaluating products and practices as a drilling and completion system, rather than selecting products on an individual performance basis. Also, the importance of properly designed and executed cleanup treatments to degrade/remove DIF filtercake is demonstrated. Finally, the benefit of post-auditing well performance to validate products and practices is shown.

P. 399
Waterfracs - Results from 50 Cotton Valley Wells
Authors: Mayerhofer Michael J. , Meehan D. Nathan
Published: December 2007

In previous publications we showed that several fracture treatments using treated water and very low proppant concentrations (waterfracs) were very successful in the East Texas Cotton Valley sandstone. This paper expands on the production examples with a more comprehensive set of production comparisons of wells completed with standard fracture treatments and waterfracs since 1995. The data sets are from three different Cotton Valley fields and include approximately 50 waterfrac treatments.

P. 489
An Example of the Drilling Analysis Process for Extended Reach Wells
Authors: Millheim Keith , Maidla Eric , Kravis Simon
Published: December 2007

This paper was prepared for presentation at the 1998 SPE Annual Technical Conference Conference and Exhibition held in New Orleans, USA, 27-30 September 1998.
Application of The First Multiphase Flowmeter In The Gulf of Mexico
Authors: Stokes Edward G. , Perry Dennis T. , Mitchell Marshall H. , Halvorsen Martin
Published: December 2007

This paper focuses on Conoco's recent installation and production measurement performance testing of the first Multiphase flow meter installed in the Gulf of Mexico. It summarizes the observations and conclusions made during the field evaluation tests. The paper also discusses the technical JIP development of the Fluenta model MPFM 1900VI Multiphase flowmeter that was used in these tests. Finally, the paper compares the meter's performance during the final development and verification testing program which took place at Conoco's Multiphase flow test loop prior to the field testing program.

P. 361
Wellsite Wet Gas Measurement System in Saudi Arabia
Authors: Al-Taweel Ahmed B. , Barlow Steve G. , Hussain Shahid
Published: December 2007

This paper describes an automated and compact wet gasmetering system that was installed and tested successfully at Saudi Aramco. The paper also describes the technology for determining individual liquid rates in production streams using the tracer dilution technique and its application in Saudi Aramco.

The system operates at a wellsite and provides continuous online measurements of liquid and gas rates for a gas well. The wet gas metering system provides reliable measurement of well producing rates and, in turn, better control of field operations and more accurate production allocation.

As a part of the wet gas metering system; the tracer dilution technology is capable of determining the magnitude of individual liquid flow rates at the wellhead, without separating the produced fluid. For a wet gas producer, this technique combined with a venturi meter can provide a three-phase measuring system, a complete alternative to a conventional welltest separator facility.

The wet gas metering system is based on the venturi principle to measure gas and condensate. The venturi principle is a proven technique which has been commercially used in oil and gas metering for years. Venturi meters have the advantages of high pressure and temperature ratings, low pressure loss, minimal wear and well established correction factors to account for entrained liquids. The rate of the entrained liquids will be measured by the tracer dilution technique.

The tracer dilution technique involves the injection of fluorescent tracers, one for hydrocarbon liquid and one for water, into the flowline and the subsequent collection of a sample at a suitable distance downstream of the injection point. The fluorescent intensity ratio of injected tracer to collected sample is used to determine the oil/condensate and water flow rates. The tracer dilution technique is viewed as a feasible and economical option to measure liquid rates in wet gas flow streams. The tracer dilution equipment is self-contained, compact, and portable.

Saudi Aramco has field-tested tracer technology in conjunction with wellsite venturi meters, as an alternative to centralized conventional test separators. Field application showed water and condensate measurement to be within +/- 10% and a gas rate measurement to be generally less than 5% of the conventional measurement technique.

P. 481
3D High-Resolution Reservoir Monitoring From Crosswell Seismic Data
Authors: Washbourne John , Bube Kenneth
Published: December 2007

Decreasing costs in the acquisition of high-resolution cross well seismic data have stimulated the development of new 3D imaging techniques that can provide accurate and cost-effective monitoring of reservoirs on scales of a few feet. We introduce an integrated 3D modeling approach that can simultaneously process data acquired from multiple crosswell profiles, can handle data acquired from highly deviated wells in areas of complex structure, and that assures 3D model continuity without interpolation. We have tested our modeling approach with fully 3D datasets and concluded that cross well seismic in three dimensions is now a reality.

P. 547
Intelligent System for Monitoring and Control of Downhole Oil Water Separation Applications
Authors: Tubel Paulo , Herbert Roger P.
Published: December 2007

This paper describes an intelligent system used to monitor and control the separation of oil from water downhole with simultaneous re-injection of the water into a zone accessible from the same wellbore. The paper outlines the individual technologies that make up the system, describes how the technologies are assembled in the wellbore, and indicates what requirements the system has of the wellbore. The paper provides a description of an intelligent system that significantly reduces water produced from a borehole while potentially increasing oil production. The paper describes the control of water flow into an injection zone and the increase in efficiency of a pump system by utilizing downhole instrumentation and intelligent systems for monitoring and control of the oil/water separation process. The intelligent system is composed of an artificial lift system, permanently deployed instrumentation for fluid and equipment monitoring, completion hardware based on an electric tubing-to-tubing choke valve, and a hydrocyclone-based oil/water separator.

P. 603
Downhole Diagnosis of Drilling Dynamics Data Provides New Level Drilling Process Control to Driller
Authors: Heisig G. , Sancho J. , Macpherson J.D.
Published: December 2007

Vibrations are inevitable in drilling. However, the severity of vibrations and their detrimental influence on the drilling process depends on bit and Bottom Hole Assembly (BHA) design, the formation being drilled and, most importantly, the choice of drilling parameter such as WOB and RPM. When adjusting the drilling parameters the driller very often relies solely on his experience which (in the best case) is gained on offset wells.

A new Measurement-While-Drilling (MWD) based service significantly improves this situation by providing real-time feedback about the drilling process to the driller. A downhole tool containing various dynamics sensors, and a high speed data acquisition and processing system, continuously monitors BHA vibrations and diagnoses the occurrence of vibration related problems such as stick-slip, whirl, bit bounce etc. The type and severity of the diagnosed vibration are transmitted to the surface and displayed on a rig floor monitor. This allows the driller to take immediate remedial action by changing drilling parameters and, more importantly, optimize the entire drilling process.

This paper presents both the downhole tool and the surface display as well as the overall service concept. The downhole processing algorithms are also outlined. Several results from first downhole runs show how dynamic dysfunctions are identified and assessed downhole.

P. 649
Modelling and Interpretation of Condensate Banking for the Near Critical Cupiagua Field
Authors: Lee Sheng-Tai , Chaverra Marcial
Published: December 2007

Near-well condensate banking has been recognized as a main factor causing deliverability loss of condensate wells. The problem is particularly acute for low-permeability high-yield condensate systems. The very high-yield nature of the hydrocarbons leads to a significant condensate dropout once the reservoir pressure becomes lower than the original dew point pressure. The low-permeability rocks, in turn, cause significant pressure drops, exacerbating condensate banking.

This paper presents a fundamental study on the mechanisms controlling deliverability of low-permeability condensate wells in the giant, near-critical Cupiagua field in Colombia. The study combines results from three areas of work, namelyinterpretation of long-term (approximately six months) well production and build-up test data for three appraisal wells,fine-grid radial single-well equation-of-state compositional modelling of the long-term well test andrigorous application and validation of the single-well pseudo- steady-state-flow theory to predicting production rates of condensate wells.

First, we present compositional modelling work to history match the production test data (e.g. GOR and production rates versus time) for three rich-condensate wells. The history-matched compositional model is then used to analyze the in- situ phase behavior and condensate banking phenomena during production. The analysis of model results provides a clear understanding on the key factors which control well deliverability. Particularly, we have found that in-situ condensate revaporization is directly related to increase of production GOR and loss of deliverability. The factors which affect revaporization are then investigated through the compositional model.

The well-known pseudo-steady-state theory for flow of single-well condensate wells is then re-examined with the aim of using the simple pseudo-steady-state formulation to calculate the deliverability of condensate wells. It is demonstrated that the in-situ phase behavior and PYT properties calculated by the pseudo-steady-state model match closely those from a general EOS compositional model. Further, the pseudo- steady-state model is shown to be applicable beyond the infinitely-acting-reservoir flow period, within which the GOR is constant. Application of the pseudo-steady-state model is demonstrated using a set of field-measured production data.

P. 631
CFD Study of Bubble Carry-Under in Gas-Liquid Cylindrical Cyclone Separators
Authors: Erdal F.M. , Shirazi S.A. , Mantilla I. , Shoham O.
Published: December 2007

The Gas Liquid Cylindrical Cyclone (GLCC) is an attractive compact separator alternative to the conventional vessel-type separator. Thus, it is important to develop predictive tools for design and to be able to improve the technology of the GLCC. Previous studies on the GLCC have focused on mechanistic models capable of predicting the operational envelope for liquid carry-over and on the understanding of the flow field in the GLCC. The main objective of this work is to investigate the behavior of small gas bubbles in the lower part of the GLCC, below the inlet, and the related gas carry-under phenomena. This investigation was performed by flow visualization and by utilizing a commercially available computational fluid dynamics (CFD) code. Simulations of single-phase and two-phase flow were carried out and bubble trajectories were obtained in an axisymmetric geometry that represents the GLCC configuration. Flow visualization experiments and CFD simulations indicate that the flow field in the GLCC below the inlet is very complex. Bubble trajectory analysis was used to quantify the effects of the important parameters on bubble carry-under. These include bubble size, ratio of the GLCC length to diameter, viscosity, Reynolds number, and inlet tangential velocity.

P. 781
Permeability Simulation in Poor Sampling Conditions
Authors: Guerreiro L. , Almeida A. J. , Soares A.
Published: December 2007

To build a reservoir geostatistical model for permeability, it is necessary to have accurate values provided by core measurements. Unfortunately, in most cases the cored zones are a very small proportion of the total length of a well. Standard regression procedures are commonly applied to find relationships between log porosity values and core measurements in order to estimate permeability in the non cored zones. In reservoirs where the relationship between porosity and permeability cannot be derived with standard regression techniques, Probability Neural Networks (PNN) can be an alternative as shown in this paper. The PNN calculate all linear and non-linear relationships between multi-variables. The output is a probability of a point (unsampled core) to belong to a given class of permeability.

In a second step, after having generated classes of permeability (stochastic simulation of a categorical variable) in the whole reservoir, another simulation (Probability Field Simulation) is applied to obtain permeability values maintaining its spatial continuity. The method developed and described in this paper preserves the heterogeneity and spatial continuity of extreme values of permeability and the spatial continuity of data.
From Matrix Acidizing to Acid Fracturing: a Laboratory Evaluation of Acid/Rock Interactions
Authors: Bazin B.
Published: December 2007

This paper was prepared for presentation at the 8th Abu Dhabi International Petroleum Exhibition and Conference held in Abu Dhabi, U.A.E., 11-14 October 1998.
Integrated Analysis of Asphaltene Deposition from Field Production Data and Laboratory Experiments
Authors: Mohammed Sabry A'Alim , Arisaka Kazuyoshi , Kumazaki Yoshito
Published: December 2007

This paper was prepared for presentation at the 8th Abu Dhabi International Petroleum Exhibition and Conference held in Abu Dhabi, U.A.E., 11-14 October 1998.
Factors Influencing Oil Demand and the Range of Call on Middle Eastern Crude production in 2010
Authors: Jordan Roy M.
Published: December 2007

The world should be grateful to those who work in the oil and gas industry, particularly to those in the upstream sector, who everyday encounter the challenges posed by the barren desert, the swamps and jungles, the offshore storms and the technological complexity of deepwater exploration and production. All this in order to ensure that oil is available to the consumer whenever and wherever it is wanted. In achieving this objective the industry has an outstanding record of efficiency. Yet public gratitude and popularity are not sentiments generally associated with the oil and gas industries. There are several explanations for this.
An Integrated Uncertainty Analysis for the Development of an Offshore Gas Condensate Field
Authors: Govan Alastair H
Published: December 2007

To evaluate reservoir development projects it is common practice to use reservoir simulation models which provide a detailed description of the reservoir performance based on a single reservoir description. Since such models are frequently very large and require considerable computing resources, it may not be possible to consider more than one or two alternative models. As a result, there is often a very poor understanding of the uncertainty in the predictions which have been obtained. Furthermore, even in situations where sufficient resources are available to run a large number of simulation cases, there is often no methodology for combining the results to produce a probabilistic view of the range of outcomes.

This paper describes a method for integrating the uncertainties in a project, including uncertainties in costs, tariffs and product prices as well as subsurface uncertainties such as fluids in place, reservoir communication and well deliverability. The method is illustrated by application to an offshore gas condensate field which is in the early stages of development planning.
Implementation of No Leak Policy in Bahja/Rima Area
Authors: Al-Wardy Ali
Published: December 2007

In 1995 Petroleum Development Oman (PDO) introduced a no leak policy for its activities. As result a review was carried out to assess the optimal way to implement the policy in all operational areas where potential for leaks existed.

One of the main causes of the leaks in PDO's production environment is flowline degradation due to the effect of internal and external corrosion.

A study carried out by PDO showed that one of the worst areas for flowline leaks in South Omam was the Rima field which had experienced sever corrosion problems in certain flowlines because of high H2S, CO2 and O2. Flowline life was less then 3 years, with some flowlines failing after only 3 to 6 month of service.

Following a successful trial, Reinforced Thermoplastic Pipe (RTP) is now being used instead of carbon steel as the flowline material in Rima. This paper describes the no leak policy implementation in Bahja Rima area and the trail and the subsequent evaluation which shown that RTP is feasible and commercial alternative to traditional flowline material.
An Improved Oil Recovery Study of Supplemental Down-dip Gas Injection, Peripheral Water Injection, and Crestal Gas Injection in a Middle East Layered Carbonate Reservoir
Authors: Mitri Karim T. , du Cray Renaud Perret
Published: December 2007

A 9 pseudo component compositional simulation study (Quarter of a full field radial) for a very mildly dipping, slightiy undersaturated, Middle East carbonate reservoir, has indicated down-dip gas injection yields recovery benefits, at relatively higher sustainable rates as supplemental to a water injection scheme or as a stand alone strategy. Common to all scenarios was crestal gas injection at the only existing gas injector.

Since miscibility is not maintained throughout in the reservoir, the impact of sweep on oil recovery is dominant again. Interfacial tension (EFT), as a miscibility indicator was used to help characterize the run results. Improved reservoir characterization models are a pre-requisite for optimization of miscible and near-miscible Gas injection processes.
Enhanced Profitability with Non-Conventional IOR Technology
Authors: van Domelen M. S.
Published: December 2007

The tenu Improved Oil Recovery (IOR) is loosely defined in the petroleum industry. Conventional IOR methods include improved reservoir management, cost reduction initiatives and advanced methods traditionally referred to as Enhanced Oil Recovery (EOR) or tertiary recovery The Norwegian Petroleum Directorate (NPD) defines IOR as "actual measures resulting in an increased oil recovery factor from a reservoir as compared with the expected value at a certain reference point in time." The NPD definition, which focuses on the concept of a reference point in time, implies that technological advances over the life of a project can be defined as IOR techniques.

This review paper will focus on the use of well technologies that traditionally were not considered IOR methods. Well-documented case histories will be presented which illustrate how the integrating of completion and stimulation design can result in enhanced profitability. Applications include: The successful completion of a deep, low permeability reservoir. This case history summarizes how state-of-the-art completion and stimulation in the early 1980's was not economical. With technological advances, however, a world record fractured horizontal well, which was completed in the 1990's, allowed the reserves to be economically produced.The use of a novel multi-stage completion/stimulation tool which allowed overall well costs to be reduced by dramatically reducing rig time.The use of suatigraphically horizontal wells in high-relief chalk reservoirs to make marginal fields in the North Sea economical.

This paper provides technology transfer by highlighting successful case histories from various locations. The importance of integrating completion and stimulation design is clearly illustrated. The necessity to evaluate total project profitability as opposed to individual components is emphasized.
Experiment of Despatching Enhanced Oil Production Through Existing Pipeline with Limited Throughput by The Use of Drag Reducing Agent
Authors: Sultan Emad , Ahmed K. Z. N.
Published: December 2007

KOC currently produces an oil field in Area A. Its production is despatched to a Tank Farm about 70 miles away through 2 nos. 30 inch transit lines. These lines are capable of handling 300 MBOPD each within the current maximum allowable working pressure of 415 psig.

It is planned to increase the daily production in Area A and sustain it for a decade or so.

Since this rate is above the current combined capacity of the two transit lines, it dictated the requirement of a third transit line.

In an attempt to explore alternative means to despatch the additional production, it was decided to examine the feasibility of enhancing the capacity of the existing lines within their pressure limitations by using Drag Reducing Agents. If found feasible this would mean substantial reduction in capital investment either by eliminating the need for a third line or reducing its diameter.

Accordingly a test was carried out in Transit Line 1 under KOC supervision by a vendor company.

The test showed that drag reduction of 55% could be achieved with 16 ppm and 68% with 34 ppm of the chemical and during the test the entire available crude could be pumped through transit line No. 1 well below its MAOP.

Data generated in the test showed that the 2 nos. 30 inch lines are hydraulically capable of handling the predicted enhanced peak production with DRA injection at appropriate ppm in both the lines.
Innovative Completion Design For Multizone Gas Injectors
Authors: Le Gurun Ludovic , Helderle Paul
Published: December 2007

The design for a multizone gas injector well has to take into account many parameters, i.e. tubing size, injection velocity, erosion, corrosion, scale deposits, zone isolation by wireline without loss of diameter, possibility of permanent logging and stimulation flexibility. The experience built on oil well producers helped a lot in choosing the appropriate equipment. Also some items had to be identified or locally modified to suit the anticipated requirements.
Production Logging in Multi-Lateral Wells – Interpretation, Problems and Solutions
Authors: Sufi Ahmed W. , Kumazaki Yoshi , Haq Shahid A.
Published: December 2007

Multi-lateral wells are being employed to improve vertical sweep by enhancing productivity/injectivity from relatively tight sub-layers of the reservoir. In addition, different direction and orientation of the drilled laterals improve areal sweep. To optimize the development plans for multi-layered reservoirs with varying permeability, quantifying the contribution across each sub-layer is necessary and can be achieved by production logging. These surveys are being conducted in Zakum Development Company (ZADCO) as part of the field development plan.

Production logging data from multi-lateral wells are often difficult to interpret due to multi-phase flow. A variety of flow patterns exist in multi-phase production. These flow patterns can vary within a particular wellbore, even at constant flow rate. Quantitative analysis is difficult in such cases sometimes, however qualitative information can be inferred. The conventional production logging technology has its limitations in analyzing the data. The analysis is dependent and based on several factors. Some of these factors are drilling/completion and the wellbore damage as a result of drilling fluids, stimulation and cleanup, the production logging tool and analysis techniques.

This paper highlights the details of above factors and how these can be handled. Also, two case histories are included to indicate the problems observed.
Design of Action Plan and Monitoring Program; Secondary and Tertiary Gas Injection Pilots in a Limestone Reservoir
Authors: Al Hendi Ahmed , Boyd Douglas , Al-Riyami Ahmed
Published: December 2007

This paper documents the design issues and considerations of a miscible gas flood monitoring program planned in 1999. The objective of the monitoring program is to assess the efficiency of gas injection as a viable means to increasing oil recovery.

Based on simulation findings, it was decided to carry out three pilots; two secondary and one tertiary miscible gas injection in three sub-reservoirs.

The pilots were designed to provide information for a future Full-Field Development Plan (FFDP). Intensive data gathering and monitoring is planned to: 1) diagnose and rectify unforeseen events early in the life of the project, and 2) evaluate each individual pilot's performance. Monitoring is planned through the pilot's wells, nearby wells and two new dedicated observation wells.