bluuebunny/crossref_metadata_2025 huggingface dataset:
Dewatering of Hunton Reservoir: What Makes It Work?
Authors: Gupta M. , Joshi R. , Kelkar M.
Published: December 2007

Proposal

Hunton Reservoir in Oklahoma represents one of the largest discoveries in Oklahoma in recent history.Since 1995, several fields in Hunton Reservoir have been exploited by various operators.The principle behind this exploitation remains the same.The wells produce large quantities of water, and along with it, significant quantities of gas, and sometimes, oil.Examination of various fields producing from Hunton reservoir indicates that the economic success from these fields is not uniform.Some fields produce significant quantities of oil, whereas, some fields only produce gas.In some fields, horizontal wells work the best, whereas, in some other fields, vertical wells do a good job.The water production from the fields ranges from as low as few hundred barrels per day to several thousands of barrels per day.

In this paper, we present the results from various fields to indicate the parameters needed in Hunton field to make it economically successful.We restrict our evaluation to parameters which can be easily measured or are readily available.These include log data (gamma ray, resistivity, neutron and density), initial potential data, production data (oil, gas, and water – if available) and well configuration (vertical or horizontal).By comparing the recovery of oil and gas to various reservoir parameters, we develop methodology for predicting the future success of the field.For example, a clear relationship exists between porosity of the rock and initial hydrocarbon saturation.Higher the oil saturation better is the recovery factor. Initial potential is critical in determining the possible recovery.Horizontal wells cost 1.5 to 2 times more than vertical wells, but may not provide the additional recovery to justify the costs.

Hunton formation is extensive in Oklahoma.If we want to extend the success of some of the fields to other areas, we need clear guidelines in terms what is needed to exploit those fields.This paper provides some of those guidelines based on the examination of the currently producing fields.
Air Compliance in the U.S.: A Systematic Guide for E&P Service Companies to Evaluate, Establish, and Ensure Ongoing Compliance
Authors: Carley J. , Malmquist K. , Davison W. , VanAllan P.
Published: December 2007

This paper discusses the complexities that E&P service companies face in the U.S. as they manage their air compliance program for their base facilities, wellsite operations, and transportation fleets while tackling the enormous amount of federal, state, county, and local air regulations. Examples of point sources (e.g., chemical blending facilities), pollution-control devices (e.g., dust collectors), and fugitive emissions (e.g., cutting sacks of dry chemicals) found within the oilfield services sector are presented, and discussions of air permit or permit exemption requirements are included for each example.

This paper is intended to share best practices for establishing and maintaining an air compliance program, including the tools (e.g., compliance matrix) and systematic techniques for managing air compliance. These practices have application across state boundaries, regardless of the site location. The compliance program includes: 1) determining if a site(s) is currently in compliance with applicable air regulations, permits or permit exemptions, including aspects related to preplanning and scope, whom to involve, audit privilege, and disclosure; 2) bringing a site into compliance once nonconformances have been identified, 3) maintaining compliance even if operational changes such as human factors, equipment, chemicals, or new construction occur, and 4) implementing operational controls to ensure compliance with continual regulatory changes.
An Innovative Way of Integrating Reliability of Intelligent Well Completion Systems with Reservoir Modeling
Authors: Ajayi A. , Mathieson D. , Konopczynski M.
Published: December 2007

When simulating the performance of intelligent well systems, the reliability aspect of the installed components is often ignored. In some cases, the components are assumed to be fully functional throughout the simulated life of the well or asset. However, for some assets, component reliability within the active period is a critical part of the overall intelligent well decision making process. This dictates whether or not the system delivers the promised value.

This paper describes a method of evaluating and quantifying the reliability of intelligent well systems based on historical data, installed components and number of zones. It then provides an approach for integrating the estimated reliability data with well performance in reservoir simulation. This integration enables the reservoir engineer to assess the time- dependent impact of the success/failure of the system on the estimated value of using the technology.

The authors presented an application of the proposed methodology to a 2-zone intelligent well system. The analysis was used to identify the downhole valve's active period and thereafter recommend a system with robust reliability data that will ensure that estimated potential value from the technology is realized. The analysis also provided insight into the impact of system failure on well recovery at different time periods.
Field-Trial Results for Produced-Water Polishing with New Vertical Units Utilizing Low Centrifugal Forces and Induced Gas Flotation for Compliance During Produced-Water Operations
Authors: Bridson L. , Darlington J. W. , Smith J. J. , Occhipinti J.
Published: December 2007

During crude oil production, a significant amount of water is co-produced. This produced water is the largest volume waste stream in oil production, with an estimated 670 million tons of produced water generated worldwide during 2002(1). Typically, a new operational field produces relatively minor amounts of water, i.e. 0-20%, of the total production. As the field ages, the water volume can increase to over 90% of the production. The offshore production facilities primarily treat oil/water mixtures by adding chemical agents to assist the mechanical separation of the fluids. The produced water is usually discharged after separation of as much of the oil and other organics as possible with current technology. At the point of discharge, typical produced waters contain oil & grease contributors at 10-40 ppm. The organic contaminants in the produced water are of increasing concern throughout the world due to their potential harmful effects on the environment.

The conventional mechanical separation devices used on the oil producing platforms can be placed in two groupings. The first grouping is high centrifugal force separators and typical examples are hydrocyclones and centrifuges. The primary advantage of this grouping is that these devices can separate large amounts of oil from water. The primary disadvantages are that these devices have difficulty with changing flowrates, changing oil in water concentration, and create small micron oil droplets by their shear forces. The second grouping is composed of polishing units and examples are horizontal dissolved gas floatation. The primary advantages of this grouping are the ability to obtain very low ppm oil in water discharge. The primary disadvantages of the horizontal dissolved gas floatation devices are the footprint requirements, changing oil concentration influent, and susceptibility to wave motion. Secondary disadvantages include the frequent requirement for routine and continuous additional chemical injection, usually water clarifiers/deoilers presenting extra operational cost and potential for increased environmental impact.

In order to overcome the disadvantages to the traditional mechanical separation devices currently utilized on oil and gas producing platforms, CETCO has developed a new vertical cyclonic separator, trademarked CrudeSep® that combines the best attributes of cyclonic separation and induced gas floatation to generate a small footprint and efficient oil and water separation. This paper will discuss the separator design and give examples of how this CrudeSep® separator can replace conventional centrifuges, hydro cyclones, horizontal dissolved gas floatation devices and degassers.
Impact of Heat Aging on Sediment Toxicity of Ester/Olefin Based Drilling Muds to Leptocheirus plumulosus
Authors: Cano M. L. , Rabke S. , Candler J. , Dorn P. B. , Louallen J. T. , Scott P.
Published: December 2007

Synthetic-based drilling fluids (SBF) have been used in a variety of drilling applications and are an important component of deepwater drilling operations. One of the applications of SBF is high-temperature wells. In order to address regulatory concerns about SBF in high temperature applications, an inter-industry study was conducted to examine the effects of temperature and time on the sediment toxicity (to Leptocheirus plumulosus) of synthetic-based fluids used for high-temperature wells. Four factors were examined: (1) ester content, (2) time, (3) temperature, and (4) alkalinity (absence or presence of green cement). Three base-stock fluids were tested, a 100% internal olefin (C1618 IO) and two traditional ester/olefin blends (10%/90% and 30%/70%). The base fluids were blended into drilling fluids and subjected to temperatures ranging from 275 to 350°F and time of exposures to temperature ranging from 16 to 160 hr.

Phase 1 toxicity results indicated that temperature and time parameters bracketed the region where ester/olefin drilling fluids transitioned from passing to failing the sediment toxicity limitation. Phase 2 used a statistical experimental design to identify significant factors impacting toxicity, and a statistical model was developed to predict sediment toxicity ratios (STR). 2-Ethyl hexanol, an indicator of ester hydrolysis, was positively correlated with increased STR and could be used to screen for potential sediment toxicity. The sediment toxicity tests, analytical measurements, and the statistical STR model supported the hypothesis that, for the types of muds studied, toxicity increased for ester/olefin blends under downhole conditions of increased time and temperature. The data from this study support caution in the use of drilling fluids containing the type of esters (traditional esters) used in this study when temperatures exceed a threshold of ~300°F. Above 300°F, these materials may break down and result in increased sediment toxicity for the drilling fluids.
Baselining and Reducing Air Emissions from an Offshore Drilling Contractor’s Perspective
Authors: Cadigan M. , Peyton K.
Published: December 2007

In recent years, global climate change and local air quality have become some of the most pressing environmental concerns. These concerns have led to collaborative international efforts to reduce the concentration of greenhouse gases and criteria pollutants. Greenhouse gases include carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) that occur naturally and as the result of human activity. Criteria pollutants include emissions of nitrogen oxide, sulfur dioxide, carbon monoxide, and total unburned hydrocarbons. Drilling contractors can play an important role in environmental stewardship by reporting carbon emissions from drilling operations, eliminating redundant emission measurements, and leading the industry in efforts to reduce these emissions.

Noble Corporation is proactively pursuing methods to manage and reduce greenhouse gases and criteria pollutant emissions, improve diesel engine efficiency, and reduce diesel consumption as a means of lowering emissions. This paper presents Noble’s current environmental initiatives and successes to date, including:The completion of a three-year base line inventory of greenhouse gas emissions from its drilling units worldwide—a first in the drilling industryVoluntary participation in the EPA Climate Leaders program, a greenhouse gas emissions monitoring and reduction programNoble’s strategy for setting targets for reducing the amount of greenhouse gases produced by its offshore drilling operations and improving diesel engine efficiency through new diesel-injection technologyImplementation of a new rig-engine efficiency program, which has led to the reduction of nitrogen oxide (NOx) emissions by 30% and fuel consumption of 2%, a cost reduction that will amount to an average of $5,000/year for each engine.

To establish a base line of greenhouse gas emissions, Noble used ChevronTexaco’s SANGEA™ Emissions Monitoring Software and equipment specifications to calculate greenhouse gas emissions retroactively and establish methods to measure greenhouse gas emissions going forward. In addition, Noble is measuring the output of criteria pollutants using Continuous Emissions Monitoring System (CEMS) technology and is evaluating the performance and durability of the technology in harsh offshore conditions, with the ultimate goal of installing gas analyzers on all of its offshore assets.

Reducing its fuel consumption not only reduces emissions of greenhouse gases and other pollutants, it promotes a cleaner workplace and allows Noble to pass along fuel cost savings to its customers.
Recent Advances in Fault Seal Analysis as an Aid to Reservoir Characterisation and Production Simulation Modelling
Authors: Fisher Q. J.
Published: December 2007

It is still common practice to adjust transmissibility multipliers of faults within production simulation models to achieve a history match without establishing whether or not the values are physically reasonable. Analysis of the permeability and threshold pressure of numerous (>2000) fault rocks from cores has provided a detailed understanding of the controls on fault rock properties, which now allows one to establish whether transmissibility multipliers incorporated into simulation models are physically realistic. Fault transmissibility multipliers within many simulation models that we have studied have proven to be far lower than core measurements suggest are reasonable. In effect the faults are being made ‘scapegoats’ to compensate for inadequacies in the physical description of the reservoir within the simulation model. The recognition of these discrepancies is, however, valuable and indicates that further characterization is required to understand the flow behavior of the reservoir.

The multiphase flow properties of faults are very rarely taken into account during simulation modeling. Theoretical, anecdotal, as well as the results from history matching of simulation models, suggests that considering the multiphase flow properties of faults could lead to better day-to-day and long term decision making. In other situations, it may not be necessary to consider the capillary pressure characteristics of faults. We therefore recommend that, prior to full field simulation modeling, simple models are constructed in which the capillary pressure and relative permeability characteristics of fault are included using a local grid refinement so that the importance of multiphase flow across the faults can be established.
Integrated Petrophysical Approach Fast-tracks Development and Results From a Heavy-Oil Reservoir in Trinidad
Authors: Sinanan B.
Published: December 2007

In planning EOR projects, teams must use all available and affordable resources to optimize results and economize on design. EOR projects are capital intensive and hence modeling the reservoir is of paramount importance before simulation and forecasting begins. Unavailability of seismic data must be substituted by core and log data to prove sand continuity, structure and stratigraphy. The conventional practice of mapping sand facies is important for depositional understanding but for EOR projects it is the flood designer's interest to have flow units mapped.

This paper incorporates an existing method, used and proven, early in the life of a wide array of reservoirs, together with revised and new concepts in conducting analysis on shallow heavy oil reservoirs. The use of the core data, log data, Winland35 equation, together with Stratigraphic Modified Lorenz plots have reduced uncertainties and have introduced more confidence in forecasting. The end products are flow units with assigned reservoir properties, to be used in simulation and smarter field development.
New Technology for the Delivery of Beaded Lightweight Cements
Authors: Kulakofsky D. , Vargo R.
Published: December 2007

The use of lightweight cements for oilfield applications has progressed from conventional systems used in the past to some very specialized blends used currently. Conventional water-extended cement slurries and their minimum densities of 11.5 – 12 lb/gal were all that were available until the late 70s when hollow spheres and foam cementing were first introduced. Technology for both foamed and microsphere slurries has evolved considerably over the last 10 years. The conventional water-extended cement slurries were considered adequate for offshore wells until the late 80s when shallow drilling hazards found in deepwater, necessitated higher performance lightweight cements.

The first specialty cements that showed success used blends of microfine cement and microspheres while the next generation of specialty cements used nitrogen and a special blend of base cement to produce high-performance foamed cements that were very successful. Advanced liquid additives then developed allowed the same high-performance results without the requirement of storing specially blended cements offshore.

Recently the introduction of new, high-strength beads has provided the advantages presented with beaded slurries under the higher operating pressures currently encountered in deep water. However, special blending, transportation, and mixing issues are still significant. These newer bead technologies have also enabled effective slurry design at lower and lower densities. In addition to the usual blending and transportation issues these new ultra-light designs present additional slurry mixing issues because maintaining a constant density no longer ensures a correct cement to water ratio.

In this paper a new technology for bead delivery is presented to illustrate how the industry can gain all of the advantages normally presented by these beaded slurries while avoiding the blending, transport, and mixing issues.

Discussion is included to describe the potential of this new technology to help reduce cost associated with offshore cementing operations. By eliminating the need for blended cement, the rig can minimize the logistical concerns, reduce waste of excess specialty blends, avoid the need of separate silos for specialty blends, and provide the capability of changing slurry density at the time of delivery.

This paper presents (1) the history and evolution from the first use of lightweight additives through this newly patent-pending technology, and (2) the methodology and guidelines for use of each technology with other lightweight technologies available.
Use of Quantitative 4D-Seismic Data in Automatic History Match
Authors: Portella R. C. M. , Emerick A. A.
Published: December 2007

This paper presents the results of a study of the use of 4D seismic data in automatic history match. The study made use of commercially available tool, SIMOPT and ECLIPSE HUTS from Schlumberger, and it utilized a simulation model based in a real offshore field. The main goal of the study was to test the feasibility of the use of 4D seismic data in the history match workflow, and also, if any gain would come from the use of this kind of data compared with the traditional well production data.

Production and seismic data were generated with a simulation model, then this model was modified and the softwares SIMOPT and ECLIPSE HUTS were used to fit the data generated in the previous step.

The seismic data improved the workflow of the history matching process, especially by helping to choose which region of the model should be modified in order to achieve the match.
An Integration of Real Options and Utility Theory for Evaluation and Strategic Decision-Making in Oil Development and Production Projects
Authors: Lima G. A. C. , Suslick S. B.
Published: December 2007

The results from the Discounted Cash Flow (DCF) are limited as a tool for decision-making in the petroleum industry because they don't properly take into account four important features of the modern investments: uncertainty, irreversibility, timing, and corporation's risk-aversion. Recent developments in real options and preference theories have allowed decision-makers to employ these two approaches separately in the process of valuation and decision-making of risky projects. This paper presents a model for valuation and decision-making integrating discounted cash flow, real options and preference theory and aims at answering the following questions: i) What is the current value of an oil project? ii) What is the optimal working interest in this project venture? iii) What are the criteria to select projects considering investment irreversibility, uncertainty and timing to implement decisions? This model is applied to valuation and decision-making of a project to produce oil from a deep-water reservoir and its results are compared to those of the traditional approach. Traditional model suggests that, as the project value is above its investment cost, the corporation should invest immediately and incur in 100% working interest. Contrarily, for an specific analysis, the integrated model suggest the corporation should invest as long as project current value is as large as 1.85 times investment cost and should take only 44.38% working interest, whereas partners fund and acquire the remaining 55.62% of the project. In general, results indicate that NPV tends to pay more attention on return and does not account properly for risk. Then, as the uncertainty (volatility) of strategic variables increase, the two models give more divergent results.
An Integrated Approach to Healthcare and Health Promotion in Both the Workplace and the Community
Authors: Luby J. , Al-Jahdaly E. A.
Published: December 2007

Saudi Aramco is probably unique in the spectrum of its provision of healthcare to both its employees and their dependents. Saudi Aramco Healthcare (SAHC) has recently adopted a strategy to ensure employee health and wellbeing by extending its Occupational Health activities to outside the workplace and into the community as a whole.
The Power of Real-Time Monitoring and Interpretation in Wireline Formation Testing—Case Studies
Authors: Elshahawi H. , Hashem M. , McKinney D. , Ardila M. , Ayan C.
Published: December 2007

Modern wireline formation testers (WFT's) are able to collect a massive amount of data at multiple depths, thus helping to quantify changes in rock and fluid properties along the wellbore, to define hydraulic flow units, and to understand the reservoir architecture. They are being routinely used in a wide range of applications that spans pressure and mobility profiling vs. depth, fluid sampling, downhole fluid analysis; interval pressure transient testing (IPTT), and micro fracturing. Due to the complex tool strings and the elaborate operational aspects involved in wireline formation testing, success requires detailed upfront planning and procedural design as well as real-time operational and interpretational support.

It is becoming increasingly critical for operating and service company experts to remotely monitor and interpret WFT surveys in real-time through web-based systems. The importance of meeting all rock and fluid data acquisition objectives cannot be overstated, given the high cost of offshore operations and the implications of obtaining false or misleading information. The main objective of real-time monitoring remains to assure that the planned data is acquired according to pre-established procedures and contingency plans. However, even in developed reservoirs, unexpected circumstances arise, requiring immediate response and modifications to the pre-planned job procedures. Unexpectedly low or high mobilities, probe plugging, unanticipated fluid types, presence of multiple phases, and excessive fluid contamination are but a few examples of such circumstances that would require real-time decision making and procedural modifications. Real-time decisions may include acquiring more pressure data points, extending sampling depths to several zones, extending or shortening sampling times, repeating micro-hydraulic fracture re-opening/closure cycles, as well as real-time permeability, composition, or anisotropy interpretation to determine optimum transient durations.

This paper describes several examples of formation tester surveys that have been remotely monitored in real-time to ensure that all WFT evaluation objectives are met. The power of real-time monitoring and interpretation will be illustrated through these case studies.
An Efficient Reservoir Simulation Approach to Design and Optimize Improved Oil Recovery Processes with Distributed Computing
Authors: Zhang J. , Delshad M. , Sepehrnoori K. , Pope G. A.
Published: December 2007

An efficient approach to obtain the optimum design under uncertainty for a wide range of reservoir simulation applications has been developed and successfully implemented.The approach discussed here significantly reduces the time required to evaluate optimum designs for improved oil recovery (IOR) processes.

Determining the optimum combination of design variables for an IOR process is a complex problem that depends on the crude oil price, reservoir and fluid properties, process performance, and well specifications.Due to the large number of design variables, numerical simulation is often the most appropriate tool to evaluate the feasibility of such a process.However, because of the economical and geological uncertainties, the optimum design should be expressed as a distribution to gauge the uncertainties.

Our innovative simulation approach has the capability to determine an economically optimum design that includes the following variables for surfactant/polymer flooding projects.

The duration of water injection prior to the surfactant flooding Surfactant concentration and slug size Polymer concentration injected with the surfactant The concentration and duration of the polymer drive The salt concentration in different stages of the flood

The uncertain parameters considered in this study were Dykstra-Parsons coefficient as a measure formation heterogeneity, average reservoir permeability, horizontal correlation length, ratio of horizontal to vertical correlation lengths, vertical to horizontal permeability ratio, residual oil saturation, surfactant adsorption, price of crude oil and chemicals, and discount rate.

In order to efficiently perform these complex design processes efficiently, a platform that distributes multiple simulations onto a cluster of computer processors has been developed. The platform integrates several oil reservoir simulators, an economic model, an experimental design and response surface methodology, and a Monte Carlo algorithm with a global optimization search engine to identify the optimum design under conditions of uncertainty.

The technique incorporates the following steps:

Factorial design to find the most influential design and uncertain factors. Response surface methodology (RSM) design over those most influential factors to fit a response surface using net present value (NPV) as the objective function. Monte Carlo simulation over the response surface to maximize the mean of the net present value and search for the optimum combination of the design variables at the same time.

This approach is applied to a field-scale surfactant/polymer flood using the UTCHEM simulator to find the optimal values of design variables that will maximize the NPV.
The Living Plan—Trading Endless Data Gathering for Quality Analysis
Authors: Christensen W. G. , Faig C. H.
Published: December 2007

The Planning Group at Northrock Resources Ltd. (Northrock) has been able to change the way that information is gathered, analyzed and shared in the Company through the development and implementation of a web-based planning system.

This new system supports their strategic planning, budgeting, and operations analysis processes and replaces a largely spreadsheet-driven system which had required considerable manual effort to update and maintain as well as being prone to data errors. In addition, the new system provides the ability to do frequent lookbacks on capital projects.

Within this new planning system, one set of economic cases become the common data source for all planning, budgeting, and reserves forecasting activities eliminating the need to reconcile data between different sources. Northrock's Planning Group can perform their analysis without making repeated data requests to the teams.

This improved system has eliminated the manual effort required to support these corporate activities for each of these processes while at the same time providing improved data quality. This allows Northrock's Planning Group to provide data analysis that is consistent, repeatable, verifiable, and timely.

The benefits of the new system and process have led to its wide acceptance - field personnel to senior executive alike have made it part of their everyday work process.
The Importance of the Stimulation Vessels in the Brazilian Offshore Basins: History of Technological Evolution
Authors: Torres R. S. , Prata F. G. M.
Published: December 2007

The Campos Basin is known as one of the most challengingdeep water basins in the world. Currently there are thirty-seven platforms, more than a thousand oil wells, and about4200 kilometers of submarine pipelines, having producedmore than 1,2 billion barrels of oil per year and 15,7 millioncubic meters of gas per day. The Campos Basin is responsiblefor more than 80% of Brazil's national production. Brazilintends to produce 2,2 million barrels of oil per day by 2007,when it will reach self-sufficiency. Therefore, the continueddevelopment of the offshore basins, such as Campos, Santosand Espírito Santo will be critical to meet this goal. In thiscontext, the technological evolution of the vessels that renderstimulation services is of fundamental importance to improvejob quality, reduce operating time, provide better protection ofthe environment, enable efficient communication, and ensureoperational viability of new techniques. This paper reports onthe history of the stimulation vessels, describing andillustrating new and state-of-the-art technology, historicalcases of pioneering operations, data transmission in real timeand the benefits for offshore operators with a global vision.
Evaluation of Production Potential using Neural Network Modeling Techniques; Comodoro Rivadavia and Mina El Carmen Intervals in the El Tordillo Field, Argentina
Authors: Marin H. , Valencio D. , Muruaga E. , Shelley B. , Sorenson F. , Tiffin J.
Published: December 2007

This paper presents a description of the process used to evaluate data from the Comodoro Rivadavia and Mina El Carmen zones in the El Tordillo Field in Argentina. The evaluation presented is holistic in nature and was performed by a team of experts. This evaluation consists of field-data quantification, integration, statistical and visual analysis, and development of a predictive artificial neural network (ANN) model capable of identifying sands with commercial hydrocarbon potential. The ANN model was used to identify patterns and trends related to the geology, reservoir, well-drilling issues, and swab-test production result. The purpose of this analysis was to identify sand attributes that are indicators of the sand's productive fluid type and capability to produce. This process was used to resolve difficult petrophysical interpretation issues associated with a complex sandstone reservoir system.

The derived ANN models were subjected to a blind test. These models were accurate 86% of the time at predicting oil/water ratios. The models were used to rapidly evaluate 149 sands in two new wells and have proven useful in the evaluation of new-well oil-production potential.
Quantitative Sand-Production Prediction: Friction-Dominated Flow Model
Authors: Cerasi P. , Papamichos E. , Stenebråten J. F.
Published: December 2007

We present here a simplified, analytical 2D model of sand production. Computing sanding for different failed zone geometries allows us to put lower and higher bounds on expected produced sand mass, for given stress and fluid flow. We assume plastified rock around the borehole and well- developed shear bands. We use the Bagnold particle flow equation, coupled to the increasing permeability and porosity in the failed zone. The calculated produced sand mass compares favorably to laboratory hollow cylinder test measurements.
Drill-Bit Catalog and Bit Index: A New Method for Bit Performance Evaluation
Authors: Macini P. , Magagni M. , Valente Pietro
Published: December 2007

The paper analyzes the application of a new method for the evaluation of bit performances. At present, the most utilized methods for bit performance evaluation are mainly based on the cost-per-foot. This approach is definitely a good reference system, but it represents only a mere economic calculation, and is not well suited for keeping into account drilling difficulties due to formation variability and directional drilling conditions. The objective of the research is both the analysis of a new drilling model for bit performance evaluation, known as Bit Index (BI), and the investigation of the possibility of BI to establish sound guidelines for the development of a mathematical tool able to help during well planning, well drilling and post-well analysis. The model was tested by mining data from the Drill-Bit Catalog (DBC) prepared at the Exploration & Production Division of Eni Group (Italy). The DBC is a database that contains both parameters for the geotechnical/geomechanical characterization of the formations and bit record/performance data. Within the DBC, three wells have been identified, recently drilled in Southern Italy. These wells have been used for the comparison and evaluation of bit performances through the BI methodology. Main results allowed to identify the bits (labeled with IADC code) that drilled with the best performances in the above three wells. The proposed model, although in its early stage of development, proved to be economic and reliable. The quality of bit performance analysis obtained with this model seems also more effective than the traditional "quick look" analysis, performed on the bit records or on the pure evaluation of the cost-per-foot.
Evaluation of Polymeric Phosphoric Ester-Based Additives as Wax Deposition Inhibitors
Authors: Gentili D. O. , Khalil C. N. , Rocha N. O. , Lucas E. F.
Published: December 2007

The challenge of producing paraffinic and heavy oils plays an important role in the scenario of technological innovations in the petroleum industry. This work presents the synthesis of a new polymer-based chemical additive, and its evaluation as an inhibitor of paraffin crystallization. This polymer was obtained by reacting a long-chain phosphoric ester with sodium aluminate, generating a molecule with relatively high molecular weight and amphiphilic character. The studies were carried out using a model-system of petroleum paraffin (P140) dissolved in paraffin solvent. Rheological, calorimetric, chromatographic and optical and electron microscopy tests demonstrated that the additive acts as modifier of paraffin crystallization, although the efficiency shown depended on the polymer molecular weight.
Strategic Optimization and Contingency Planning Model for Oil Spill Response
Authors: Costa L. R. T. A. , Ferreira V. J. M. F. , Andrade F. N. P. , Antoun A. R.
Published: December 2007

Proposal

Response to marine pollution incidents requires careful advance planning to ensure that the impact of the pollution is minimized. A high priority must be given to developing contingency plans that will ensure prompt response to mitigate the adverse effect of any spill. Oil spill response planning will prescribe actions that will be performed under emergency conditions and attempts to minimize damage to the ecology and to the quality of human life.

This paper deals with strategic optimization model that prescribe a minimum total cost plan to build new storage location and/or expand existing ones and to purchase new equipments and pre-position them and a contingency plan which determines what systems must be allocated to enable an effective response for each likely oil spill scenario.

To date few studies have addressed the strategic aspect of oil spill cleanup management. The spill optimization models can contribute with contingency plans that are prepared by responsible parts in case of a spill and could be used as decision aid by all of these parts. They can be applied whenever new equipments are purchased or whenever any responsible party is preparing a contingency plan.

In this paper is described a model that deals with modern oil spill cleanup requirements that include time-phased response. The model proposed considers further where to locate the protection systems that must be deployed to the priority areas associated with spill scenarios immediately after a spill occurs.

The model is applied in a case that involves three companies that wish to update their contingency plan using the services of one spill response company. This response company will use the strategic response model for oil spills, in order to help it to check whether it's necessary to expand its response structure, and if so, the model will help to outline a lower-cost configuration that will be adequate to the new situation, fulfilling the legislation requirements.

This model can be adopted by industry to facilitate contingency planning.
Analytical Modeling of 1-D n-Component Miscible Displacement of Ideal Fluids
Authors: Pires A. P. , Bedrikovetsky P. G.
Published: December 2007

Enhanced Oil Recovery (EOR) methods include injection of different fluids into reservoirs to improve oil displacement. These processes can be divided into two main categories: thermodynamical and hydrodynamical ones. Analytical models for 1-D displacement of oil by gas have been developed during the last 15 years. It was observed from semi-analytical and numerical experiments that several thermodynamic features of the process (MMP, key tie lines, etc) are not dependent of transport properties. The model for one-dimensional displacement of oil by miscible fluids is analyzed in this paper. The main result is the splitting of thermodynamical and hydrodynamical parts in the EOR mathematical model. The introduction of a potential associated with one of the conservation laws and its use as an independent variable reduces the number of equations. The reduced auxiliary system contains just thermodynamical (equilibrium fractions of each phase, sorption isotherms) variables and the lifting equation contains just hydrodynamical (phases relative permeabilities and viscosities) parameters while the initial EOR model contains both thermodynamical and hydrodynamical functions. So, the problem of EOR displacement was divided into two independent problems: one thermodynamical and one hydrodynamical. Therefore, phase transitions occurring during displacement are determined by the auxiliary system, i.e. they are independent of hydrodynamic properties of fluids and rock. For example, the minimum miscibility pressure (MMP) is independent of relative permeabilities and phases viscosities. The splitting technique may be used for the solution of Riemann problems and for non-self-similar displacement of oil by rich gas solvent slug with lean gas drive considering ideal behavior of the fluids, i.e. constant distribution coefficients. For 3-D displacements, the splitting is valid if and only if the total mobility is constant. It allows the application of the obtained 1-D analytical solutions in streamline simulators. The technique reduces significantly the amount of calculations for sensitivity study of gasflooding processes with respect to transport properties: auxiliary thermodynamic problem may be solved once for given reservoir and injected compositions; variation of relative permeabilities and viscosities should be performed just in the solution of one transport equation.
Analytical Solution for Transient Temperature Field Around a Cased and Cemented Wellbore
Authors: Mendes R. B. , Coelho L. C. , Guigon J. , Cunha G. G. , King V. P. S. , Landau L.
Published: December 2007

Thermal recovery techniques have been widely used to enhance production in heavy oil reservoirs. The high temperatures increase the fluid mobility. The thermal stresses generated by high temperature changes may cause material damage, such as collapse, buckling or shear failure of the casing and hydraulic sealing loss of the cement sheath due to its cracking.High temperatures in open-hole completions may lead to grain shearing or cracking, increasing effective borehole radius.The evaluation of the stress state induced by temperature changes is of major interest in oil wellbore drilling and exploitation.

The temperature field around the well is usually evaluated by numerical techniques such as the finite difference method or analytically through Laplace transform, assuming a constant temperature at the borehole wall.The method proposed herein considers the radial heat conduction through the bore-face.Multilayer cylindrical of heterogeneous materials in perfect thermal contact and with constant physical properties composes the geometry of the problem. The heat conduction equation is evaluated through the separation-of-variables method, using Bessel functions.The problem domain is defined at the finite interval bounded by the radius of thermal influence, evaluated as the heat front advances. At the borehole wall, the boundary condition is given by a constant heat transfer rate.

This solution was implemented in a computer program.The results were compared with numerical solutions. They presented a better computational performance in terms of time and model simplicity.
New Well Architecture and Structural Modeling Based on the Integration of Seismic Data, Well Logs, Core, Production and Geomechanic Data in "Carito Field", Northern Monagas Basin, Venezuela
Authors: Gomez G. , Martinez A. , Sifontes E. , Rodriguez P. , Arcia L. , Planchart C.
Published: December 2007

Reservoirs at the Northern Monagas Basin, EasternVenezuela, are characterized by a very complex structural modelof sand-shale sequence (highly faulted system), as well as a diverse column of fluids, such as light oil, condensated, gas and water.Depths range within 15,000 to 17,000 feet.A preliminarily model was generated from surface seismic data before drilling, and was carefully evaluated and updated based on the information obtained from drilled wells.

This paper presents an interesting case of design of new well architecture based on structural and reservoir re-interpretation of a block at Carito Field, after the integration of new 3D surface seismic data, Borehole seismic data (VSP), Crosswell seismic data and well logs (Images, Dip, Cross Dipole Acoustic logs), core and production data.

The use of novel evaluation techniques of structural geology and reservoir were complemented with the geomechanical modeling of the area. The results of this integration are used for the design of new well geometry for the optimization of the drainage of reserves associated to this reservoir.
Enhanced Oil Recovery with CO2 Sequestration: A Feasibility Study of a Brazilian Mature Oilfield
Authors: Gaspar A. T. F. S. , Suslick S. B. , Ferreira D. F. , Lima G. A. C.
Published: December 2007

This paper investigates the economic feasibility of extending the production life of a small mature oilfield using EOR coupled with CO2 sequestration. We describe the physical aspects of this project, as well as, present a breakdown cost methodology in order to estimate the main financial determinants of the integrated EOR with CO2 sequestration, that is, the cost of capture, compression, transportation and storage. A cash flow and risk analysis is carried out whose main result is a NPV of US$ 3.2 million. A sensitivity analysis shows that project NPV is most sensitive to oil price, oil production and CAPEX. In addition, an environmental benefit of storing 0.73 million tonnes of CO2 over 20 years is achieved.
Inorganic Scale Control Within MEG/Methanol-Treated Produced Fluids
Authors: Jordan M. M. , Feasey N. D , Johnston C. J.
Published: December 2007

The control of inorganic scale (carbonate/sulphate) has been a challenge to the production of hydrocarbon and associated water for over 50 years. The current trend in the industry to develop satellite fields with longer tie backs and in deeper water has resulted in new challenges to control such scale deposits during hydrocarbon production. The lower fluid temperatures that are present in these subsea developments during fluid production increases the sulphate scaling tendency and makes scale control very difficult over the long residence time now experienced due to the tie back lengths. The introduction of methanol, mono ethylene glycol (MEG) or tri ethylene glycol (TEG) to control hydrate risk presents new challenges in terms of increased scale tendency (dehydration of brine) and interactions of the hydrate control chemicals with scale inhibitor performance.

For these challenging environments a full understanding of the evolution of the brine chemistry through the field life cycle is essential (types of scale, supersaturation changes). This paper will outline the process by which this risk assessment of scale formation in the presence of hydrate control chemicals is made and how the scale control measures for effective scale management of subsea developments is carried out. Development of new and improved scale inhibitors for these types of applications within both methanol and MEG hydrate control chemicals will be outlined. Field case studies from the North Sea and Southern Africa will be used to illustrate the scale control challenges and how they have been overcome with engineering and production chemical solutions.
Detailed 3D Seismic Interpretation Using HFI Seismic Data, Fault Throw, and Stress Analysis for Fault Reactivation in the Cogollo Group, Lower Cretaceous, Urdaneta West Field, Maracaibo Basin
Authors: Galarraga M. , Hansen B.
Published: December 2007

As a part of the static and dynamic reservoir modeling project of the Cogollo Group in the Urdaneta West Field (SIEP & SVSA, 2003-2004), a detailed structural interpretation of 1150 km2 of HFI ("high frequency imaging") seismic volume was carried out.Five different trends of faults were interpreted, as done onthe previous PSI ("pre-stack time imaging") seismic volume two years ago (Galarraga & Engel, 2002), but substantially increasing the number of NW-SE trending normal faults interpreted. This fault trend has developed and grew parallel to the maximum horizontal stress through time. Therefore, they were used to guide the local changes in orientation of the maximum horizontal stress (sHmax) which are related to the preferential flow direction of the fluids in the reservoirs.

Fault length vs fault throw plot and fault throw analysis for the different trend of faults interpreted in the Cogollo Group suggest that most of the faults interpreted in the field are composed of more than one fault actually hard-linked in the Cogollo Group. Furthermore, comparison of the fault throw profile at the different horizon levels indicates that the throw decreases with depth in the NW-SE trending normal faults. This behavior has been observed in normal faults formed under oblique-slip faulting, according to sandbox analog experiments (Naylor, et al, 1986; Richards, 1991).

Estimation of the current stress state (Hansen and Galarraga, 2003-2004) indicated that the Urdaneta West Field is actually under strike slip tectonic (sHmax > sV > sHmin). Stress analysis for fault reactivation was carried out over the different trend of faults, indicating that the WSW-ENE fault trend is critical stressed (i.e. capable of slipping), and therefore permeable, allowing hydraulic communication between the Maraca and Apon reservoirs within the Cogollo Group. This is supported by dynamic reservoir modeling (Rodriguez and Morell, 2003-2004), which indicated a need for hydraulic communication between Maraca and Apon reservoirs.