bluuebunny/crossref_metadata_2025 huggingface dataset:
Establishing Key Waste Disposal and Recycling Performance Indicators
Authors: Carley J.
Published: December 2007

The performance of a company's waste management program can be efficiently interpreted from waste disposal and recycling metrics for industrial and hazardous waste disposed or recycled from its facilities. This paper presents systematic methods for collecting, interpreting, and illustrating corporate waste disposal and recycling data. The generated performance profile encompasses waste management and minimization, benchmarks with objectives, and cost control issues, and it provides information to predict long-term environmental risks.

We present best practices for waste disposal and recycling parameter identification (e.g., treatment categories vs. cost and volume), efficient data collection (e.g., incorporating metric requirements of preferred vendors), and data presentation and evaluation for both hazardous and nonhazardous waste streams. These practices reduce information collection costs and time-consuming data evaluation.

In this paper we demonstrate how applying this performance data reduces long-term environmental risks and liabilities to the company through careful vendor selection, continuous vendor evaluation and monitoring, and confirming the choice of preferred vendors on a geographic basis. The volumes of waste disposed or recycled are assessed to determine if treatment categories with higher environmental risk are being used and if shifting to lower risk categories is feasible. In addition, the company demonstrates the benefits of including the waste disposal and recycling performance metrics in the environmental risk management and awareness training programs.
Implementing an Environmental Excellence Program: Encouraging Personnel to Go Beyond Compliance and Environmental Performance Metrics
Authors: Edgar J.
Published: December 2007

The majority of companies strongly support and encourage the active commitment of all their employees to protect our environment. This commitment is in the best interests of customers, employees, stockholders, and those in the communities in which we live and work.

How can a company demonstrate going beyond the traditional, but absolutely paramount, routes of compliance programs and metric measurement?

Line management can fulfill its leadership in this area by empowering employees to incorporate environmental initiatives into their normal course of business. The difficulties arise when trying to capture what local environmental initiatives have been conducted, especially if one operates in a global reach.

This paper will demonstrate how one service company implemented and encouraged an employee-driven Environmental Excellence Program. Since the inception of the Environmental Excellence Program in late 2001, more than 20 projects have been recognized. In the following pages we share some of these success stories.
An Integrated 3D-Seismic Exploration Method for Fractured Reservoirs in Tight Gas Sands
Authors: Reeves J. J.
Published: December 2007

In a tight gas exploration and development study conducted for the U. S. Department of Energy by GeoSpectrum, Inc., a 3D seismic interpretation method for fractured sandstone reservoirs is developed. The method is based on a comprehensive reservoir characterization of the Lower Dakota Sandstone in a gas producing Unit, Rio Arriba County, New Mexico.

The following reservoir attributes are used: Lead areas containing brittle reservoir rocks are defined by geologic attributes such as acoustic impedance and a collocated cokriged clay volume map for the Lower Dakota.A gas sensitive AVO seismic attribute, near-trace stacked phase minus far-trace stacked phase, phase gradient, is used to further define drill locations having high gas saturation.Reservoir fractures are predicted using seismic lineament mapping in the reservoir section.A seismic interval velocity anisotropy attribute is used to investigate fractured reservoir potential in tight sands up hole from the main reservoir target.

A four well drilling program was recently completed to test GeoSpectrum's fractured gas reservoir prospects and exploration technology. The nearly 100 percent success ratio of the drilling program indicates GeoSpectrum's fracture detection method is ready to be applied on a commercial basis.
The Application of Transient Pressure Testing to Track Phase Boundaries during Production—A One-Well Case Study from UKCS
Authors: Dahroug A. , Zheng S. , Baily J.
Published: December 2007

In gas fields, the most common way to define the drive mechanism is by using the material balance equation to determine the gas initially in place (GIIP).

Yet, the P/Z plot upon which the material balance equation is based can be extremely insensitive in practice, leading to a misjudgement of the drive mechanism and serious GIIP overestimation. The more sensitive Havlena-Odeh method is recommended as a means of checking the validity of the P/Z plot and as a better application of the material balance method. Aquifer support in dry gas fields will affect the material balance equation greatly and adds complexity to its application. Associating aquifer support with the difficulty of economically monitoring the gas/water contact (GWC) throughout the life of the field creates an ambiguity in efficient reservoir management. In large, long-life gas fields, 4D seismic may be a viable approach to monitoring aquifer movement, but in small developments or marginal satellites, this may prove uneconomic. One method for reducing the uncertainty of the GWC in a dry gas reservoir is being able to monitor it efficiently and economically.

This study seeks to ascertain from reservoir simulation models whether time lapse pressure transient testing during production is reliable for identifying aquifer encroachment toward producing wells in real time and also provide a useful tool for reservoir management.
Risk Analysis Method of Continuous Air Emissions from Wells with Sustained Casinghead Pressure
Authors: Duan S. , Wojtanowicz A.
Published: December 2007

Well cement problems such as small cracks or channels can result in gas migration and lead to sustained pressure at casingheads (SCP). Regulations require removal of significant SCP while tolerating small SCP during production operations. However, SCP of any size must be removed prior to well plugging and abandonment (P&A) as it is believed that even very small leaks might lead to continuous emissions of gas to the atmosphere. In some wells, however, small gas leaks may diminish in time as the gas migration channels are plugged off by the gas condensate. Thus, the objective of this work was to develop a method for computing potential of self-plugging in wells with SCP using priciples of phase behavior and theory of two-phase flow in small channels.
Towards Better Correlations for Water Production Prediction Using Sensitivity Analysis and Numerical Simulation Models
Authors: Zamonsky G. , Lacentre P. E. , Larreteguy A. E.
Published: December 2007

Most of the work related to water production in oil wells found in literature deals with the problem of determining the critical flow rate for water coning, but very few has been done to determine the water production above the critical rate. Moreover, the available correlations use to differ considerably.

The aim of the present study was to determine the performance of water production in a single well for a range of operational conditions and petrophysical parameters characterizing a petroleum reservoir.

A well simulation model in radial geometry was constructed, considering undersaturated oil and including a water contact. The model was simple enough to allow for the simulation of the thousands of cases required to perform the sensitivity analysis at reasonably low computer cost. Variation intervals were taken for selected parameters; for the rest of them reasonable average values were considered. This technique applied to a numerical simulation model constitutes a powerful tool for generating enough statistical data to analyse the behaviour of water production.

A database consisting of almost 20,000 cases was built, comprising both cases in which the production is carried out with a flow rate smaller than the critical one, and cases in which the cone instability is reached and the flow rate is higher than the critical one.

Existing correlations for breakthrough time and water production were checked for validity against the database. It was found that, although in some cases they provide a reasonable approximation, there are many cases in which this is not true, despite the relative simplicity of the cases analysed.

Based on this evidence, it is clear that better, more general correlations are needed. A correlation for breakthrough time was developed, for a wider range of validity than existing ones with respect to the reservoir parameters. As future work we plan to analyse the large amount of useful information generated and stored in our database to seek for functional relationships between water production and operational and petrophysical parameters.
Continuous Improvement in Fracturing Fluid Design in Gas Fields of the Italian Adriatic Sea Region
Authors: Cobianco S. , Pitoni E. , Ripa G. , Perez D. , Patey M. , Jeanpert J.
Published: December 2007

An aggressive design and testing program addressing a wide range of technical and environmental issues has been implemented specifically to optimize frac-pack processes in the Italian Adriatic sea region. Three formulations of viscoelastic surfactants have been developed to improve productivity and reduce environmental issues in these mineralogically immature (dirty), unconsolidated sandstone reservoirs. The first-applied viscoelastic surfactant (VES) carrier fluid used a cationic surfactant; the newly developed fluid systems use anionic and zwitterionic surfactants. Laboratory testing has focused on improving fracture conductivity, reducing formation damage, and complying with Italian environmental regulations. This paper describes the laboratory development and field application of an environmentally friendly VES system that complies with current offshore Italian regulations.

In formations with high clay content, filtrate from cationic VES fluids exhibited low retained permeability owing to surfactant adsorption on the clays. Methanol was added to these fluids to solve this problem; however, environmental constraints require the elimination of methanol. Recent laboratory tests have proven that the newly developed anionic and zwitterionc VES fluids achieve excellent permeability recovery after backflooding, without requiring methanol. The laboratory study was also performed to optimize the VES concentration as a function of the desired rheological and suspension properties. The zwitterionic VES could also be formulated with heavy brines such as calcium chloride (CaCl2) and seawater, thus providing a significant cost savings.

Results of this process confirm that environmentally friendly systems provide dramatically improved, cost effective fluids, while reducing the environmental impact of VES applications that use alcohols.

The paper also presents a field case incorporating details of execution and production results. The treatment process has been continuously reviewed to provide a more technical and environmentally acceptable service.
High-Resolution Environmental Survey around an Exploration Well Drilled with Formate Brine in the Barents Sea, Norway
Authors: Zuvo M. , Bjørnbom E. , Ellingsen B. , Buffagni M. , Kelley A. , Trannum H. C.
Published: December 2007

The present paper gives an overview of the environmental impact of cuttings discharges on the bentic sediments, three years after drilling an exploration well (7122/7-1) with formate brine (mixture of potassium and sodium formate) in Production Licence 229 in the southwestern part of the Barents Sea.

Eni conducted a high resolution environmental survey on the physical, chemical and biological conditions of the benthic sediments, in the vicinity of well 7122/7-1 drilled in 2000 in PL229. The cuttings and mud from the well were released to the environment as the drilling operation was conducted before the political decision to restrict the discharge of cuttings and mud from operations using water based mud (WBM) in the Barents Sea1.

The aim of the study was to verify findings in a life cycle assessment (LCA) that had been conducted for formate brine, which concluded with:

"The findings of the study indicate that the discharge of moderate amounts of Formate Brines is not likely to lead to potentially significant negative impacts on the marine environment." 2

Samples were collected from 27 stations surrounding well 7122/7-1. Apart from the reference station, all stations were within 500 meters of the well head (reference station about 3 km to the south of the well head). Samples from 22 stations were analysed physically/chemically and 19 stations were analysed biologically, in addition to the reference station. As stations were very close to each other, very high sampling accuracy was of crucial importance.

The findings in this study are in line with the conclusion in the LCA as only minor environmental impact in the vicinity of the drilling location was detected.
A New Inhibitive Water-Based Fluid: A Completely Cationic System
Authors: Rosa R. C. R. S. , Rosa A. L. A. , Farias S. B. , Garcia M. H. , Coelho A. S.
Published: December 2007

The development process of new technologies in drilling fluids has established that the fluid should have viscosity control and clays inhibition.Some other aspects as fluid loss control and grout thickness had become almost that decurrent of the action of the main products.The search of a highly inhibitive water-based drilling fluid (WBDF) system has been a continuous purpose in the drilling fluid industry.

We have designed and developed new materials that will improve the inhibition capacity of water-based fluid, besides favoring a complete rheology and fluid loss control of the system.Parameter viscosity reached great evolution in the last decades with the implantation of high performance polymer, capable of substituting the bentonite.Through this, the fluid with low solid became the key of the success in perforation fluids.

The developed system consists of an environment-friendly cationic polymer as shale inhibitor, a fluid-loss control, and a polymer that provides viscosity and gel structure. Components were designed for high performance water-based drilling fluids, and present the versatility to be used as much with industrial water, as seawater or saltwater, maintaining the fluid performance. This work will discuss some properties of this system, comparing with the traditional system used by Petrobras - Brazil.
Naturally Fractured Reservoirs: How To Estimate Secondary Porosity
Authors: Pérez-Rosales C. , Luna E.
Published: December 2007

Naturally fractured rocks are very complex systems. Due to their morphological complexity, numerical simulation of naturally fractured reservoirs is lacking wholly reliable procedures for determining secondary porosity. The use of incorrect values for this variable may lead to significant deviations when simulating secondary or enhanced oil recovery processes. In this work, a procedure is presented for estimating secondary porosity. The proposed procedure is based on new ways of analyzing well log data of total porosity and formation resistivity factor. It takes into account the fact that fractures behave as flow channels whose conductivity is much greater than that of the matrix. Fundamental to the procedure is a precise physical interpretation of the parameters appearing in the generalized Archie equation, and an adequate use of the concept of rock tortuosity. This concept is used as a classifying tool to identify: (1) useful data for estimating secondary porosity, (2) zones containing conductive material, and (3) very low conductivity compact zones. Two application examples are presented to illustrate the operational aspects of the procedure.
Developments in the Visualisation of Well Tubular Condition
Authors: Oliver D.
Published: December 2007

Modern logging tools for the investigation of the condition of downhole tubulars provide multiple outputs derived from an array of sensors. These sensors provide simultaneous readings and are arranged so a single set of measured data is derived from a cross-section of the casing or production tubing. Data sets are rapidly updated as the tools are run in the well providing a detailed series of depth related cross-sections.

In addition to producing conventional logs in real-time, this data can be used to generate 3D images. Until recently the images produced from array tools were limited to internal dimensions. New thickness measuring tools, together with improved software, provide thickness data which can be displayed either as an image based solely on thickness or combined with internal measurements to provide 3D pictures that are analogues of the actual metal remaining within the well. These images can be used to assess both internal and external corrosion and/ or damage.

This paper describes in outline the tools used to produce the data. It employs examples from both the testing phase and initial operational deployment of the new tools to illustrate the benefits of the image approach to displaying data.
The Use of Risk Adjusted Values in Exploration Portfolio Management
Authors: Moore C. R. K. , Moyes C. P. , Patterson P. D.
Published: December 2007

Maximizing Expected Present Value predicts that firms will seek 100% working interest in attractive ventures. However, firms frequently desire less than the entire working interest, and clearly pay much less than EPV to participate, management behavior often explained as a result of firms’ risk aversion.

Although there is little published evidence that firms routinely calculate Risk Adjusted Values (RAV), they provide a useful way to quantify risk aversion. This is not a new tool, as methods of deriving RAV and an Optimum Working Interest have been available in the literature for some time. Previous studies, which we review, have concentrated on defining a firm's Risk Tolerance, a necessary input in determining RAV.

We have expanded the use of RAV in a number of ways. Firstly, we believe that a firm's RT is not constant, but varies by business unit to match the strategic direction of the firm. Secondly, we use actual and hypothetical examples to illustrate the use of RAV in (a) rationalizing the Fair Market Value of exploration portfolios, (b) defining the relative contributions of firms’ exploration assets in mergers and acquisitions, (c) assessing farm-out values and targeting potential farminees, (d) selecting aligned partners for bidding groups and (e) government use for designing license rounds.

Existing applications of RAV have usually been restricted to a simple lottery in which a single success leg is represented by mean success. This ignores the uncertainty in the success leg, with RAV being independent of the variance of the underlying reserves distribution. Through analysis and simulation, we review the sensitivity of RAV to reserves and value uncertainty.
Assessment of Rock Mechanics Properties Starting From Geophysics Logs With the Garcia-Garcia: A General Model for Calculating Total Compressibility and Formation
Authors: García-Muñoz N. A. , García D. , Ortega-Serrano R.
Published: December 2007

This paper uses the effective media theory to estimate the heterogeneous distribution, the bulk and formation compressibility in the reservoir, in function of rock elastic properties, such as, the volumetric moduli (K) and shear (μ) vs. depth, by means of field available data, such as geophysical logs (density and sonic).

Results from four (4) naturally fractured carbonated reservoir are shown and from one sand reservoir counting on log information for validation.
Potential of Different Polyamino Carboxylic Acids as Barium and Strontium Sulfate Dissolvers
Authors: Lakatos I. , Lakatos-Szabó J.
Published: December 2007

The studies were focused on evaluation of different scale dissolvers for barite sag or barium sulfate scales, while the chemically similar compound, the strontium sulfate obtained much less attention. Therefore, an extensive research programme was launched with the aim at evaluating the potential of seven different polyamino carboxylic acids (NTA, EDTA, DCTA, DTPA, EGETA, HEDTA and TTHA) using both technical and economic aspects to compare the behavior of these two compounds.

Dissolving capacity of each compounds was determined under equilibrium conditions as a function of BaSO4 and SrSO4 concentration in both the presence and absence of reservoir rock. The absolute and relative selectivity of dissolution were precisely analyzed. Dissolution of all components was followed in time and kinetic calculations were made. Results of the measurements provided reliable data for comparison of dissolution capacities under identical chemical conditions.

On the basis of the experimental findings it was concluded that the sequence of dissolution capacity is different if the results were evaluated in technical or economic sense. It was also shown that the preferentially used compounds (e.g. DTPA, and particularly EDTA) are not the best choices when technical considerations are only enforced. Namely, the practice justifies their application at the expense of poor efficiency. Results of that systematic analysis may open new vistas in mitigation of formation damage caused by BaSO4 or SrSO4 and accelerate the search for more effective mixtures of complex-forming dissolvers.
Corrosion Control during Acid Fracturing of Deep Gas Wells: Lab Studies and Field Cases
Authors: Al-Mutairi S. H. , Nasr-El-Din H. A. , Al-Muntasheri G. A. , Al-Driweesh S. M.
Published: December 2007

Acid fracturing treatments are used to enhance gas production from tight, deep carbonate reservoirs in Saudi Arabia. The produced gas has a regional variation between 0 and 10 mol% H2S. This variation in H2S content has impacted the metallurgy of well tubulars used in these areas. Gas wells in the high H2S area are completed with low-carbon steel (L-80 and C-95); those in the low H2S area are completed with super Cr-13 tubulars.

Acid systems used to fracture these wells included: regular, emulsified, and in-situ gelled acids, all based on 28 wt% HCl. However, 15 wt% HCl – 9 wt% formic acid was used to stimulate wells completed with super Cr-13 tubing. High temperatures (275°F) encountered in deep wells, the presence of high H2S content and the use of large volumes of concentrated acids render corrosion control of tubulars a very difficult task.

Experiments were performed to develop a cost-effective acid system to enhance the productivity of deep gas wells, while maintaining the integrity of well tubulars. Acid fracturing treatments were monitored in the field and well flow back samples were collected following these treatments. The concentrations of key ions were measured in these samples including iron and manganese for completions with low-carbon steel tubulars and chrome, molybdenum, and nickel for completions with super Cr-13.

Analysis of flow back samples following the initial acid fracturing treatments showed that the return samples contained high concentrations of acid (up to 16 wt% HCl) and total iron (up to 20,000 mg/l). The presence of iron was a major concern during acid fracturing treatments. Modifications of the corrosion inhibitors package, increasing soaking time and over flush volume resulted in better results. Most importantly, the integrity of well tubulars was maintained. This paper discusses lab studies and application of these modifications in the field.
A General Approach to Well Evaluation
Authors: Diyashev I. R. , Economides M. J.
Published: December 2007

Petroleum well performance and its evaluation are clearly some of the most important functions of modern production engineering. We present a general approach to the issue by employing the field-derived, dimensionless productivity index (JD) which we calculate from measured information including the production rate, reservoir and flowing pressures and well and reservoir data.

The dimensionless JD is independent of well completion, i.e., it transcends the geometry, whether the well is under radial flow, hydraulically fractured or whether it is vertical or horizontal. The determined JD's are then compared against benchmarks we have developed for optimized production such as the concept of Unified Fracture Design (UFD) or maximized horizontal well performance. We have developed deterministic methods for this analysis and new means to graphically depict the results.

Such evaluations are important in concluding whether the well is underperforming or whether the past engineering could have been improved and by how much. Decisions such as refracturing, the redesign and improvement of future treatments and whether to fracture vertical or drill horizontal wells can be readily made.
Introduction of a Dual-Cell Depurator for FPSO Application-Theory to Practice
Authors: Rivet C. , Movafaghian S. , Chen J.
Published: December 2007

This paper is intended as part of the continuous development of Wemco® Dual-Cell Cylindrical Depurator® and adaptation of Induced Gas Floatation technology to meet the demands of today's offshore production practices as the best-available-technology (BAT). The focus of this paper is relating theory to practice for this new and proven technology and the real life example of one of its applications. This paper is presenting the problem solving and selection process adopted by ChevronTexaco North America's Operations Team at Typhoon Production Facility, located in deep water Gulf of Mexico. The paper compares alternative solutions and economical advantages and disadvantages of each alternative. It also provides an in-depth analysis of the performance achieved after installation of the Dual-Cell, based on the theoretical model developed for this equipment.
Sustaining Fracture Conductivity
Authors: Weaver J. D. , Nguyen P. D. , Parker M. A. , van Batenburg D.
Published: December 2007

The industry has developed standard methods to effectively evaluate the propping agents used in hydraulic fracturing operations. The understanding gained from the consistant application of the methods has greatly helped to optimize productivity.of hydraulicly fractured wells.

This paper presents two mechanisms that may significantly increase the understanding of how to optimize fracture conductivity to sustain productivity. The standard methods use well "aged" (passive) proppant and simulated formation materials; whereas, in practice, formation faces are highly activated as an immediate result of mechanical fracturing, as is a significant portion of the pumped proppant.

The chemistry that occurs at freshly exposed mineral surfaces is different than that of the aged surfaces used in the laboratory. For example, condensation of polymers on freshly generated surfaces may result in polymer chains becoming anchored to the surface. This anchoring prevents some polymer from being removed by normal gel-breaking mechanisms and forms points of attraction for the collection of broken polymer and fines debris, leading to significant permeability damage and reduced fluid recovery.

After a treatment when pressure is relieved and well clean-up begins, temperature and stress gradients are high; significant crushing of proppant and formation material may occur as a packed fracture moves toward an equilibrium condition. The presence of hHigh-ionic-strength fracturing fluids, particularly at high pH, may promote a rapid mineral diagenesis-type reaction that leads to proppant compaction, embedment, and crystalline overgrowth permeability damage.

This paper provides laboratory and field data supporting the conclusion that the application of a thin, highly dielectric, polymer film to coat proppant can result in a long-term reduction in mineral dissolution rate, compaction, embedment, and polymer anchoring sites. Field data shows this effect has a dramatic improvement in fracturing fluid recovery and well productivity.
Experimental Analysis of Swirl Tubes as Downhole Desander Device
Authors: Martins J. A. , Rosa E. S. , de Oliveira Souza R.
Published: December 2007

This work analyses the impact of the viscosity increase on the separation efficiency of swirl tubes based on experimental data. The data is reduced using dimensionless analysis. A functional relationship between the separation efficiency and the dimensionless groups is obtained. It discloses how the separation efficiency depends on the liquid viscosity, flow rate, solid size, and other geometrical parameters of the separator.It helps to push the design of these desander devices to new scenarios with heavy crudes or to oil-water mixtures with low water cuts prone to evolve to oil-water emulsions.
Reliability and Uncertainty in Reserves: How the Industry Fails, and a Vision for Improvement
Authors: Demirmen Ferruh
Published: December 2007

Review of field reserves from different parts of the world reveals that reliability of reserves estimates is rather poor. Many fields show wide fluctuations in reserves estimates through time, both at pre- and post-production stage, with a tendency toward underestimation. Accompanying this trend, uncertainty attached to the "best" reserve estimate does not shrink with additional data, defying intuition. Reasons for such phenomena are varied, but one fundamental reason is the approach the industry generally takes toward reserves estimation. Reserves variations, whether in upward or downward direction, adversely affect project economics.

Factors that affect reserves evaluation include reservoir aspects, development scheme, operations and technology, economic and regulatory aspects, and "intangibles" that relate directly to human input and conduct. In the last-named category, proclivity to ignore statistical rules leads to distortion in reserves and associated uncertainty estimates.

The vision toward improving reserves reliability involves a multi-prong approach that tackles all these root causes. An optimal appraisal strategy that addresses the key subsurface uncertainty, due regard to statistical rules, and use of volumetric methods that consider different scenarios and put the evaluator in contact with "real" data, are viewed, among others, as providing tangible improvements.
TNK-BP Wellwork Performance Management
Authors: Postnikov M.
Published: December 2007

TNK-BP operates 250 fields (the majority of those are mature water-flooded) with 2003 annualized average liquids production of 1.28 mln BPD and August 2004 record liquid hydrocarbons of 1.5 mln BPD. The Company's investment portfolio is dominated by wellwork program which compensates production decline and serves the purpose of maximising production and allows reaching planed growth targets. The wellwork program in 2003 included more than 4300 jobs and more than 5000 in 2004 on 15000 active producers with annualized average incremental oil rate of 189,000 BPD in 2003 and 224,000 BPD in 2004. This year program is of the same and even greater scale. All of the Company's wellwork activity is tracked in the WETS™ wellwork evaluation tracking process, a BP heritage tool. This process was implemented in Sidanco assets in December 2002 – February 2003 and in TNK assets in November 2003 – April 2004. The WETS™ wellwork evaluation database includes results of the following TNK-BP activity - drilling operations, rate addition wellwork on producers, and injector wellwork. This database has more than 9900 jobs as of January 2005. The results of less than a year of full implementation of the tool in TNK-BP are shown in this paper. This paper will illustrate how TNK-BP manages large scale upstream investment activities using the WETS™ wellwork evaluation tracking process. Examples of intra-company benchmarking will be explored to illustrate how major projects in the company are assessed and compared. This paper will also illustrate how historical performance is analyzed to underpin confidence in forward planning and ranking of projects.
The Impact of Injection with Fracture Propagation During Waterflooding Process
Authors: Souza A. L. S. , Fernandes P. D. , Mendes R. A. , Rosa A. J. , Furtado C. J. A.
Published: December 2007

Waterflooding is still the most common method used worldwide for improving oil recovery, either after production by primary mechanisms or at early stages of the field lifetime.

During the waterflooding process, injectivity decline can occur due to rock and fluids characteristics, well geometry, and formation damage caused by fines migration, salt precipitation and by solids and oil particles present in water entrainment. One of the best ways to avoid injectivity decline is the Injection with Fracture Propagation Pressure (IFPP).

In this work a methodology for modeling fracture propagation is presented, as well as the sweep efficiency effects due to IFPP, using an in-house geo-mechanical simulator combined with a commercial reservoir simulator.

The simulations show that the impact on oil recovery due to IFPP can be high, depending on injection pressure, fracture propagation velocity and direction, type of well (vertical or horizontal), well pattern, distance injector-producer and starting time of IFPP. By the other hand, the impact of injectivity loss on the Net Present Value may be high, so that the benefits of injection rate maintenance with IFPP can overcome a possible negative impact on sweep efficiency.

The conclusions point out to the importance of knowing the geo-mechanic reservoir characteristics in order to choose well type, injection pattern and well spacing, so that the benefits of IFPP can be completely achieved.
Produced Water Reinjection in Petrobras Fields: Challenges and Perspectives
Authors: Furtado C. J. A. , Siqueira A. G. , de Souza A. L. S. , Correa A. C. F. , Mendes R. A.
Published: December 2007

Petroleum industry has been more and more concerned about the effects of produced water disposal in the environment, particularly in offshore fields. Increasing amounts of produced water have being processed by companies and the search to alternatives for the produced water destination has become a priority for the major operators.

As oilfields reach their maturity, the water cut increases, and Produced Water Re-Injection (PWRI) in the producing formation seems to be a convenient way for its destination. Disposal in adjacent, non-oil bearing formations is also an attractive option to be considered.

This paper presents an overview of the main PWRI projects in Petrobras. Petrobras has been re-injecting water in their mature onshore fields for many years, and it is starting re-injection projects in offshore Campos Basin.

Technical, economical and environmental aspects of PWRI are presented. Related topics, like injectivity loss due to PWRI, injection above the fracture propagation pressure, PWRI effects on oil recovery and reservoir souring potential are discussed.
Making Sense of Return Permeability Data Measured in the Laboratory
Authors: Han L. , Lohne A. , Stevenson B. , Stavland A.
Published: December 2007

Proper selection of reservoir drilling fluids (RDF) or drill-in fluids can minimize formation damage and maximise well productivity or injectivity. Typically, fluid selection involves pre-screening of fluid candidates followed by laboratory return permeability testing of a selected few. However, as the fluids often have different fluid loss and return permeability properties, the final decision as to which fluid to use is often arbitrary. These difficulties stem from the fact that there is no recognised method for comparing formation damage potential of fluids with different fluid loss and return permeability profiles and the lack of valid models for upscaling laboratory data to field skin factors.

In a recently finished EU project, a methodology was developed to bridge the gap between the laboratory measured data and field skin factors, so laboratory fluid loss and return permeability data can be interpreted in field skin terms. This will help the fluid engineers to select the least damaging fluid for their application. The methodology makes it possible to compare laboratory results obtained under different test conditions, and to estimate skin factors for different reservoir sections from a single return permeability test. This functionality is very useful for calculating the productivity of complex reservoirs with anisotropy and heterogeneity.

For correct upscaling of return permeability to field skin, both the fluid loss and return permeability profiles are required. This paper recommends dynamic fluid loss for return permeability testing. This paper also recommends a slight change to routine formation damage test procedures to obtain the return permeability profile necessary for upscaling. Detailed laboratory data analysis techniques to generate input parameters for the developed models are also reported.

The above mentioned methodology has been built into a simulator in Microsoft Excel with a user friendly interface.
Alternative Material-Balance and 1D- Flux Simulation Applied To Expedite Analysis of Mature Fields
Authors: da Costa Peron J. R.
Published: December 2007

Estimate the remaining potential of mature fields with multiples reservoirs can sometimes be an uncertain time consuming task. As a help in such cases, this paper deals with the concepts of a "modified" one-dimensional flux simulator, able to handle gravitational segregation, phase dispersion, conning, fingering, etc.
Reservoir Representation for Flow Simulation
Authors: Romeu R. K. , Paraizo P. L. B. , Moraes M. A. S. , Lima C. C. , Lopes M. R. F. , Silva A. T. , Rodrigues J. R. P. , Pacheco F. P. T. , Cardoso M. A. , Damiani M. C.
Published: December 2007

Reservoir flow modeling involves two aspects: a functional model (flow equations and numerical methods) and a representation model (related to the reservoir description) - and this last aspect is usually the critical one. Reservoir representation is different from reservoir characterization. It is not a question of describing the reservoir in a more or less exhaustive or realistic way, but a question of incorporating relevant information into the flow simulation model, considering the syntax of the flow simulators and the relative impact of information on the simulation results. Reservoir representation makes the bridge between reservoir characterization and flow simulation.

This paper presents selected results from a cluster of applied research projects in reservoir representation for flow simulation. It includes: (1) gridding issues in the context of integrated reservoir studies (discussion of terminology, grid specification, generic format reading, etc.);(2) identification and representation of critical heterogeneities of turbidite reservoirs; (3) assigning transmissibility multipliers across partially sealing faults in a field case; (4) incorporation of production data in reservoir flow models with an example of application; (5) hyperdocumention for reservoir simulation files (making use of HTML tags to get a much richer documentation of the flow simulation model).
Successful Application of a Unique and Low Friction Frac-Pack Fluid in Gulf of Mexico Deep Wells
Authors: Gadiyar B. R. , Morales R. H. , Nelson E. , Barton K. , Fischer D. , Sorrells D.
Published: December 2007

In recent years, there has been an increase in exploration and drilling activity in deepwater and deep-shelf gas and oil fields in the Gulf of Mexico. The economic feasibility is dependent on completion efficiency, with the goal to optimize the production rate. In addition, most of these formations require sand control to prevent completion failure. To achieve optimum hydrocarbon production and prevent sand failure, frac-pack is considered the best completion option. However, performing frac-packs in deep reservoirs (>15,000 ft) with high reservoir pressures (>10,000 psi), and temperature variations pose many challenges such as pump rate limitations due to high friction pressure and fluid-stability problems due to temperature changes.

To address these challenges and overcome the limitations of conventional fluids, a unique borate crosslinked that employs an encapsulated borate crosslinker with various base-fluid compositions was developed. The fluid has a broad temperature stability range: 40°– 350°F.The crosslink-delay can be varied between 1-20 minutes without affecting fluid stability.The proppant-transport ability is excellent.

These attributes allow fluid injection at optimum rates with minimum friction pressure. This paper presents Gulf of Mexico, deepwater case histories that demonstrate the successful application of this fluid. The fluid design, fluid properties, and job execution, are discussed in the paper context.
Risk Analysis in the Determination of the Best Exploitation Strategy Using a Calibrated Reservoir-Simulation Model
Authors: Wences A. , Tomas M.
Published: December 2007

This paper introduces a new perspective in reservoir exploitation strategy using risk analysis. In a recent paper1, Acosta introduced an integrated systematic approach to determine the best exploitation strategy from a calibrated deterministic reservoir simulation model. The methodology presented in this work is a step forward, since the deterministic methodology is now combined with stochastic reservoir modeling and economic risk analysis, to improve the decision making process under uncertainty.

A few calibrated reservoir simulation models generated from reservoir characterization techniques, using probabilistic modeling, are used to represent less likely, most probable and optimistic scenarios. Acosta's technique1, 2 is then applied along with an economic evaluation risk analysis program, to determine the optimum exploitation scheme for each scenario.

This new workflow allows the determination of the optimum number of additional wells, their grid locations, as well of assisting to define the most appropriate enhanced recovery process. Key portfolio planning input, such maximum gross rates, production and injection infrastructure requirements, Capex and Opex profiles, are the results from this integrated technical and economical optimization approach.

Reservoir management and strategic decision making process are improved, since both technical and economical risk analyses are considered. The most valuable plan is obtained for all options, along with their overall related uncertainties. Managers, therefore, can select the best alternative for field development, together with an assessment of the key parameters and knowledge to be determined, in order to reduce the project risk.
The Value of Permanent Downhole Pressure Surveillance in the Amherstia/Parang Field, Offshore Trinidad
Authors: Baksh K.
Published: December 2007

Proposal

The Amherstia platform produces mainly gas from the Amherstia/Parang field offshore Trinidad and was commissioned in 2000 to supply gas to Trinidad's domestic market and Atlantic LNG Trains. The field has approximately 2.8 tcf of proven reserves of which 0.76 tcf have been produced to date. There are 14 wells on production, which peaked at 1.0 bscfd in 2003 with initial well rates averaging 100 mmscfd. The platform also boasted of the first 7-inch horizontal gas well completion in Trinidad with an initial rate of 225 mmscfd. Current production is 600 mmscfd, which feeds a 2.1 bscfd of sales from bpTT's Columbus fields.

Rapid and continuing expansion of the domestic and LNG markets in Trinidad has demanded great emphasis on gas deliverability and reserves assurance. Reservoir surveillance was seen as critical to the fore-mentioned, hence Permanent Downhole Gauges were installed to provide real time pressure and temperature. The data can be accessed through the SCADA system real-time or through an online database.

Data gathered from planned and unplanned shut-ins have been used to frequently update well and material balance models. This data is invaluable in determining gas in place, identification of compartmentalization, reservoir drive mechanisms and generation of reliable deliverability forecasts. Quick identification of any aquifer presence results in necessary actions taken to optimize off take rates to maximize reserves. Drainage volumes have also been tied to geologic and 4-D Seismic data thus optimizing well count.

The high capture frequency database has also enabled pressure transient analysis to be done over the entire pressure history of the wells allowing for the calculation of permeability and frequent updates of completion efficiency (skin and turbulence) as it changes through the life of the well. In addition it is possible to detect boundary (water) movement and provide alternative means of calculation of gas in place, instead of just static shut in pressures as in the traditional material balance technique; typical yearly surveillance cannot facilitate this. This paper will demonstrate the value of permanent downhole pressure surveillance in the Amherstia development by reviewing a number of case histories.
Twenty Years of Steam Injection in Heavy-Oil Fields
Authors: de Souza J. C. , da S. Cursino D. F. , de O. Pádua K. G.
Published: December 2007

This paper reviews the twenty years of steam injection in heavy oil fields of Alto do Rodrigues area. The review includes the beginning, consolidation and expansion of this enhanced recovery method. Main topics involve project management of cycled injection and steam drive along with steady improvements on the quality control of the whole steam generation process. At the end, this work shows the positive impacts on the recovery factor and environmental issues.
New Opportunities in an Exploitation Area - Maria Ines Field - Austral Basin - Argentina
Authors: Gutierrez F. E. , Saccavino L. L. , Cagnolatt M. , Echevarria C.
Published: December 2007

Proposal

The Maria Ines Field is productive from the M3 reservoir sand and is in a mature stage of exploitation. The purpose of this study was to search for new opportunities near and around productive oil fields.

This integrated work was based on a stratigraphic regional model with additional focus on the structural framework. The facies are developed in an estuarine depositional environment, were 2nd, 3rd and 4th order sequences were recognized. The 4th order hierarchy defines the main reservoir boundaries, whose thickness is controlled by unconformities and flooding surfaces.

The most promising traps were identified below the "known" oil water contact, and a portfolio consisting of step out wells was developed based upon structure size estimates, as well as using a probabilistic calculation of OOIP and risk.
Reservoir Surveillance in Gas Reservoirs, Offshore Trinidad
Authors: Jemmott S.
Published: December 2007

Proposal

This paper illustrates five examples where the application of reservoir surveillance has improved the understanding and ultimately the performance of gas reservoirs. The reservoirs in question are located off the southeast coast of Trinidad in the Cassia, Flamboyant, Parang, Amherstia and Immortelle fields. Gas is produced to satisfy both Trinidad's domestic and international LNG markets. With the contractual demands brought about by these markets, reservoir surveillance is seen as the key to identifying new well opportunities to sustain supply.

A host of surveillance tools have been employed in Trinidad, including cased hole logging tools such as the reservoir saturation tool (RST) to track movement of fluid contacts, and the production logging tool (PLT) to identify producing intervals and fluid types. Data from both permanent and temporary downhole pressure gauges have been used in material balance modeling and pressure transient analysis to assess reservoir size and drive mechanisms, quantify reserves and deliverability forecasting. Examples of these best practices are discussed within this paper.