bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Oil Recovery by Retrofitting Subsea Processing
Authors: Rasmussen Andreas W.
Published: December 2007

A short presentation of subsea processing with focus on the most important drivers that would give high NPV on a prospect.

Operational experience from the world's first subsea processing station on Troll.

Status from the ongoing Demo2000 project - Subsea Sand Management

Learnings and experience from a JIP in subsea processing with recommendations to how to cooperate between oil companies and supplier industry (AkerKværner, ABB, BP ChevronTexaco).
Promoting Real-Time Optimization of Hydrocarbon Producing Systems
Authors: Saputelli L. A. , Mochizuki S. , Hutchins L. , Cramer R. , Anderson M. B. , Mueller J. B. , Escorcia A. , Harms A. L. , Sisk C. D. , Pennebaker S. , Han J. T. , Brown A. , Kabir C. S. , Reese R. D. , Núñez G. J. , Landgren K. M. , McKie C. J. , Airlie C.
Published: December 2007

The term "Real-Time Optimization" (RTO) has rapidly found its way into common usage in the oil and gas industry, as it already has in many others. However, RTO in the oil and gas industry is usually used more as a slogan rather than describing a system or process that truly optimizes anything at all, let alone does so in real-time.

In this paper, we describe what RTO means in the exploitation of hydrocarbons and what technologies are available now and are likely to be available in the future. We discuss how it is misunderstood and what real financial benefits await those who adopt it. Furthermore, we are working toward developing a method of classification to allow us to establish where a field operation lies on the RTO ladder, and to help plan a strategy to generate the benefits that moving up the RTO ladder can offer on specific fields and assets.

The paper also describes a new SPE Technical Interest Group (TIG), explaining why it has been formed, and outlining its objectives and some planned deliverables.
Leadership And Performance Management: The Key To Exploiting Hidden Returns
Authors: MacLeod Andrew
Published: December 2007

The structure of the North Sea oil industry, with its extended supply chains and high reliance on contracted out services, has provided an ideal environment for sub-optimal performance to develop, become accepted, and form part of our culture. Partially due to a lack of clarity and agreement on performance goals, and partially due to under-developed management and leadership skills, this inefficiency now provides "hidden returns" for operators, waiting to be exploited like untapped reserves.

Whether introducing new technology, or seeking to maximise the value of existing strategies, organisations are now recognising that it is the practices and behaviours of their personnel that determine whether their full potential is realised.

This paper describes some of the factors that inhibit performance within the oil industry and offers a methodology for continuously improving efficiency and financial returns. Two case studies are presented, demonstrating the effectiveness of the process in practical situations.
The Northwest European HSE Case
Authors: Windhorst Gert-Jan , Richardson Jay , McLean Ian , Krahn Dennis
Published: December 2007

Moving rigs across North Sea borders is costly and inefficient. Thus, area regulators requested IADC's N.Sea Chapter cooperate on a Northwest European HSE1 Case.

The framework illustrates substantial drill crew input to identify hazards, assess risks, and maintain controls based on a decade of experience in stringent HSE regimes.
Life of Field Energy Performance
Authors: Svalheim Stig , King Dave C.
Published: December 2007

BP has, in collaboration with the Norwegian Petroleum Directorate (NPD), conducted an energy performance study based on life of field data's from the Norwegian Continental Shelf (NCS).

This paper shares lessons learned from this work, in terms of methodologies, energy performance, and measures to improve energy efficiency.

Key observations from the study: the energy performance level on the NCS is excellent, BP has developed a new tool that improves the understanding of energy performance and identifies where energy could be saved and commercial values created, energy consumption on oil producing platforms is fairly constant whereas the % energy consumed increases significantly as a field matures.
Health Risk Assessment And Health Monitoring
Authors: Sætersdal Lars , Skeggs John
Published: December 2007

A theoretical and practical model that combines the two and its implementation on three mobile drilling installations offshore

Monitoring the health of employees in order to detect possible long-term effects of adverse working environment conditions has been a task for several years and is also a regulatory requirement related to a systematic follow-up of the working environment in the petroleum industry.

To design a model that effectively combines the results of working environment exposure data and possible adverse health effects, and at the same time being the practical tool we have been looking for as an occupational health service team, has been a major challenge for us for a long time.

The theoretic approach we chose has been similar to the safety risk analysis models, but the terms probability of events and the event severity (consequence) are replaced with exposure level and potential health effect severity. We also introduce the term "health-risk score" which is the product of the two above mentioned elements.

This health risk score triggers off different actions. These include the possible need for follow-up exposure measurements in the working environment, an evaluation of the use of personal protective equipment, the need for further education/training among the employers/employees and, of course, -what kind of specific measures are to be chosen and included in the health monitoring programme and at which intervals.

To support our work we have developed a software programme which is of major importance in combining all the results of the actual working environment exposure data and keeping record of the health monitoring programme for the different departments and employee categories in a company.

We strongly believe that this approach benefits both the company in its aim for a systematic follow-up of the working environment, and it gives us, as their partner in the QHSE field, the practical tool we have been looking for.

In 2001 we started the process of implementing this model in a company we have been collaborating with as an occupational health service for several years. This company is an oil drilling company managing three mobile installations in the North Sea.

We will present how the practical implementation took place and the experience so far.
Improving Fundamental Safety of Xmas Trees and Wellheads for Platforms
Authors: McKenzie J. , Webb P. , Copland M.
Published: December 2007

This paper outlines the principles and actual learning from the whole process of designing the inherently safer production Xmas Trees and wellheads and highlights the benefits of early consultation with the regulator during the design phase of a project. The paper demonstrates how to reduce the risks to individuals by the rigorous application of good engineering practice.
Strategic Value of a Systematic Energy and Greenhouse Gas Management System
Authors: Nordrum Susann , Duff Alexandra , Lee Arthur
Published: December 2007

Description

ChevronTexaco believes that global climate change is an important issue and is taking action to address it in a comprehensive way. We recently made publicly available our corporate-wide system for estimating greenhouse gas emissions and energy utilization. This paper specifically focuses on the advantages of using a systematic, auditable energy and greenhouse gas (GHG) management system in a mature oilfield. Material in this paper is based on our experience in using Chevron Texaco's SANGEATM Emissions Estimating System at upstream locations in the North Sea and worldwide.

Results, Observations and Conclusions

A credible, systematic approach, such as the SANGEATM Emissions Estimating System, provides strategic value to mature fields that are facing increasing constraints on greenhouse gas emissions and increasing energy costs. By having a rigorous and verifiable inventory of greenhouse gas emissions, operators can demonstrate to government and nongovernmental organizations how greenhouse gas emissions change over time as a field ages. In addition, energy utilization and greenhouse gas emission information can be used to guide investments, in order to achieve the maximum energy efficiency and greenhouse gas emissions minimization per barrel produced.

Applications

ChevronTexaco's new system, the SANGEATM Emissions Estimating System, is an automated, electronic data management information system that is designed to gather monthly energy and greenhouse gas emissions data from worldwide exploration and production, refining and marketing, petrochemicals, transportation and coal activities. ChevronTexaco Corporation and its Chevron, Texaco and Caltex facilities enter data to calculate greenhouse gas emissions and energy utilization on a monthly basis. Energy and greenhouse gas emission estimates are reported to ChevronTexaco Corporation each quarter.

Technical Contributions

The SANGEATM Emissions Estimating System is now publicly available. ChevronTexaco is making the system available free of charge in order to promote standardization of methodologies, and to improve comparability of greenhouse gas inventory information across the petroleum industry worldwide. We believe that widespread use of the SANGEA(tm) software will help provide a standard methodology for our industry. The American Petroleum Institute and several petroleum companies around the world have requested review copies of the software system.
Using TAML-3 Multilateral Technology to Deliver a Technologically Challenging, Fast-Track, One-Well Development in the Southern North Sea
Authors: Hay Bill , Horne Ken
Published: December 2007

As part of its exploration and development strategy of selectively developing resources in existing basins, BP has chosen to develop its Hoton field in the southern North Sea using a "normally unattended" satellite platform tied back to the West Sole pipeline system. To optimize volumes and drive efficiencies, BP has applied novel technologies, including multilateral completions, to the Hoton development.

This paper describes how the Baker Oil Tools HOOK Hanger multilateral completion system evolved during the recompletion of Hoton well 48/7 b-12 to provide a fit-for-purpose solution for the application. The paper also describes some of the many "firsts" achieved during the re-completion of well 48/7b-12 and describes how the well was successfully completed in a timely and efficient manner.

The Hoton field, operated by BP, lies 8 miles northeast of the West Sole field in North Sea blocks 48/6 and 48/7b. The field is composed of a tilted fault block structure with 918.6 ft relief on top of the Rotliegend formation, and bound on its southern, western and eastern flanks by faults. The southern bounding fault separates the Hoton Main area from a separate structure called Hoton SE.

Hoton well 48/7b-12 was drilled in 1996 as an appraisal / development well for the field, but lower than expected gas production rates resulted in the development being put on hold until technology had matured to a level that would better exploit the prospect. In 2000, careful appraisal of the Hoton prospect concluded that re-entering well 48/7b-12 and delivering a tri-lateral well would provide an economically feasible completion option. This conclusion assumed a one-well development tied to a monopod, minimal facility Normally Unmanned Installation (NUI): in summary, a technologically challenging, fast track-development.

In 2001, the Hoton 48/7b-12 well was developed as a Technical Advancement of Multilaterals (TAML) Level 3 well using the Baker Oil Tools HOOK Hanger system.
Applicability of Vapor Extraction Process to Problematic Viscous Oil Reservoirs
Authors: Karmaker Kulada , Maini Brij B.
Published: December 2007

Production of heavy oil and bitumen from subterranean deposits is difficult, even under best of circumstances, due to very high oil viscosity. The recovery by currently used thermal based methods is more problematic and uneconomical for some of the reservoir scenarios, such as the reservoirs with an overlying gas cap, bottom water table, high water saturation, low porosity, low thermal conductivity, thin pay zone, vertical fractures and/or fissures, etc. Currently there is no proven recovery technique that can be economically applicable to such viscous oil reservoirs. However, there is a huge amount of hydrocarbon resource present in such reservoirs that can only be exploited with new concepts.

The Vapex (vapor extraction) process has recently emerged as a superior technology for the recovery of heavy oil and bitumen reservoirs. Recent research has shown that the process is highly energy efficient, environmentally friendly, causes in-situ upgrading, and requires low capital investment compared to its competitor SAGD process. The objective of this work was to evaluate the effectiveness of this newly postulated Vapex process to some of these problematic reservoir scenarios. An extensive experimental study has been carried out in a partially scaled physical model. Some experimental results, theoretical analysis, and the applicability of this process to such problematic viscous oil reservoirs are presented and discussed.
Two-Phase Flow Rock-Typing: Another Perspective
Authors: Hamon G.
Published: December 2007

Petrophysical units, also called rock-types, are usually defined to help the reservoir engineers to assign petrophysical characteristics to different zones of a detailed description of a reservoir. Estimate of initial hydrocarbons in place accounts for such petrophysical units which are usually generated, using both single-phase data, i.e. porosity, permeability, and two-phase drainage data (i.e capillary pressure curve) and coupled with sedimentological descriptions. It is then frequently assumed that these rock-types are valid to assign two-phase flow characteristics, such as relative permeability curves, to a reservoir, whatever the recovery process. This paper shows that this assumption is often not correct, using several field examples, including sandstone and carbonate reservoirs. Based on a large number of core flood results, it is shown that the usual rock-typing methods may not capture the actual variability of relative permeability curves, and particularly:

Porosity, permeability or pore size distribution might be poor indicators of actual controls for two-phase flow, whatever the technique used to combine them into a rock-type representation There is no systematic correspondence between rock-types used to estimate hydrocarbons in place and those required to describe production behaviour, There is no systematic correspondence between sedimentological facies and rock-types required to describe production behaviour,

It is also shown that:

Multivariate descriptions, including petrophysical characteristics, mineralogical data and wettability indicators, succeed in capturing the actual variability of relative permeability curves and should be the basis for the generation of multiphase flow rock-types. Two-phase flow rock-types should be dependent on the recovery process.

Consequences on sampling for coreflood programmes, as well as inputs of simulation models are pointed out.
Experimental Relationships between Residual Gas Saturation and Initial Gas Saturation in Heterogeneous Sandstone Reservoirs
Authors: Suzanne K. , Hamon G. , Billiotte J. , Trocmé V.
Published: December 2007

Residual gas saturation is considered to be a key factor in evaluating gas recovery from a lean gas reservoir invaded by water. Residual gas saturation is known to be dependent on both pore network characteristics and initial gas saturation. In this paper, sixty experimental relationships between initial gas saturation (Sgi) and residual gas saturation (Sgr) are presented for a large set of sandstone samples and checked against former empirical Sgr-Sgi laws. Previously, no more than two authors have presented more than twenty full experimental Sgr-Sgi relationships.

The core plugs are selected from two different sandstone gas reservoirs and from Fontainebleau sandstone outcrop. Porosity and permeability plugs, respectively range from 0.06 to 0.25 and from 0.1 to 2000 mD, with Sgrm values ranging from 0.04 to 0.65.

Two-phase Sgr is achieved by controlled evaporation - spontaneous imbibition methods. The main results are:

Two-phase Sgr-Sgi experimental relationships have piecewise linear form, characterized by two parameters: the maximum residual gas saturation, Sgrm, and the saturation corresponding to the intersection of the two segments, Sgo. Sgo was found to be dependent on the amount of microporosity and different from Swir. The constant Sgr region confirms that the microporosity does not trap gas. The linear Sgr/Sgi region corresponds to gas trapped in the macroporosity. None of the hyperbolic laws is able to describe correctly the observed experimental behavior. Jerauld's and the simplified version of Land's relationships are the poorest estimates of Sgr as a function of Sgi. The best relationship to describe Sgr-Sgi curves is the piecewise linear Aissaoui's law. It results in a significantly better agreement with experimental data than Land's original formulation. Both forms rely on two fitting parameters. Our experimental results show that porosity (or permeability) and the amount of microporosity along with the initial gas saturation control Sgr values.
Flow of Hydrates Dispersed in Production Lines
Authors: Peysson Yannick , Nuland Sven , Maurel Philippe , Vilagines Régis
Published: December 2007

This paper presents some results obtained in a Research project managed by IFP (Institut Français du Pétrole) and IFE (Institute for Energy Technology), where the objective is to study the transport of hydrates in production lines.

A number of research projects are devoted to the study of thermodynamic equilibrium in the presence of hydrates, and the kinetics of hydrate formation, in order to develop prevention tools like hydrates inhibitors, insulation.... But with the development of deep water and ultra deep water production schemes where these technologies become expensive and some times limited, a fair prediction of hydrate formation and transport conditions becomes necessary for anticipating the design of the production facilities and could help the production engineers to make the appropriate decisions. In the literature, however little efforts have been directed towards the hydrodynamic modeling of hydrate transport. This project aims at the study of hydrate slurries in flowing conditions and particularly in multiphase flow lines. Experimental data in flow loop are presented. Comparisons have been made with flow models. In presence of hydrate crystals, the production fluid resembles a slurry with effective transport properties. This study indicates that the presence of particles in the flow tends to increase the wall drag and, consequently, influences the production capacity of the line. Moreover the settling trends of these solid particles can complicate the problem. Discussions about these issues have been done.
Reliable Sub-Sea Umbilical and Down-Hole Injection Systems are an Integral Component of Successful Flow Assurance Programs
Authors: Shirah A. D. , Place M. C. , Edwards M. A.
Published: December 2007

Sub-sea and down-hole chemical injection systems are necessary components in most successful flow assurance programs. Specially formulated inhibitors and dispersants used in these systems provide solutions to a variety of deepwater and subsurface problems. The prevention or alleviation of wax deposits, asphaltene deposits, hydrate plugs, scale deposits and corrosion depends on an integrated chemical system. This system includes chemical formulation, capillary/umbilical design and proper operation and maintenance.

This paper will review these necessary elements of a successful chemical system: chemical formulation, capillary/umbilical design and proper operation and maintenance. Formulation will take account of the requirements for quality, cleanliness and performance, physical properties targets, and compatibilities with well fluids, other treatment fluids, and system components. Design considerations will include compatibilities with the treatment fluids and the external environments as well as mechanical properties. Operation and maintenance will assure continued functionality by providing for cleanliness, redundancy and unexpected problems in every step of the transportation and delivery system.

The chemical delivery system must be effective, reliable, forgiving and redundant. Replacement or repair of the system as well as loss of production due to failure can be very costly. In the paper's review of the sub-sea and sub-surface chemical injection systems, laboratory data in conjunction with successful and unsuccessful field results will be used to provide lessons learned and best practices.
Water Injection Optimized with Statistical Methods
Authors: Palsson B. , Davies D. R. , Todd A. C. , Somerville J. M.
Published: December 2007

The complexity of the water injection process is often underestimated and asset managers often focus on controlling the water injection costs rather than maximising the injection water, value creation. This paper discusses a several methods to evaluate the techno-economic issues surrounding water injection, ranging from discounted cash flow analysis to portfolio analysis. It is shown how quantitative technical and economic analysis of the available options allows optimum decisions for process management. Advance planning ensures that changes in water injection performance do not surprise managers since they are prepared for such possible events, appreciate the likelihood of their occurrence and are able to quickly identify the optimal response.

In many situations, statistical methods are the most appropriate toos to identify these optimal responses. The industry has experience with these methods and the required input data is often available. Monte Carlo methodology is shown to be a powerful alternative to Portfolio Analysis when the input data for the latter is incomplete or there are insufficient alternatives available.

Portfolio Analysis emphasises the value of diversity. This can be important as the presumption of the simpler methods that all events are independent is often not true. E.g. the chance of a success of a stimulation treatment is not neccessarily independent of the chance of success in next well.

A decision tree analysis of a water injection case study is used to quantify the "Value of Information" and to show how spending significant resources on extended technical studies can be justified. This extra data might lead to a more "advanced" project design, ensuring that operations staff are better prepared for upsets later in field life. Monte Carlo Analysis shows that, although this "advanced" option is likely to create significantly more value, there is still a small possibility that the "low cost" option is more profitable.
Expandable Tubular Casing Repairs: Four Case Histories
Authors: Wright Jon C. , Moore Melvin J. , Winters Warren J.
Published: December 2007

In November 2002 BP America installed four expandable tubular casing patches, totaling 5,000 feet in length, in three Texas Panhandle gas wells that had been shut-in due to corrosion leaks. The casing repairs were successful and the wells were restored to production. The jobs were completed consecutively in rapid sequence. This contributed to improved workover economics and quick implementation of lessons learned. This paper details project objectives, job design and implementation, plus problems encountered, unique solutions and best practices established as the result of this work. Successful application of this new technology has given the producing asset a cost-effective alternative to the standard practice of squeeze cementing to fix casing leaks.
Integrated Geostatistical Reservoir Characterization of Turbidite Sandstone Deposits in Chicontepec Basin, Gulf of Mexico
Authors: Abbaszadeh Maghsood , Takano Osamu , Yamamto Hiroshi , Shimamoto Tatsuo , Yazawa Nintoku , Sandria Francisco Murguia , Zamora Guerrero David H. , de la Garza Fernando Rodriguez
Published: December 2007

This paper presents a pixel-based hierarchical geostatistical modeling of submarine fan turbidite sandstone deposits in Tajin and Agua Fria fields of Chicontepec basin in the Gulf of Mexico. Methods are discussed for identifying and dividing the stack of heterogeneous siliciclastic sediments in these fields, using sequence stratigraphy, petrophysical well log characteristics, geological facies model and 3D seismic data.

An integrated multidisciplinary geostatistical reservoir characterization is conducted in two main steps. First, a large-scale reservoir framework of multiple sequence and subsequence surfaces is constructed based on the integration of data sources of geologic well markers, petrophysics, and seismic horizons. Second, high-resolution 3D distributions of reservoir properties are generated, accounting for inherent inter-relationship among reservoir property data and the three main data scales of log, sub-sequence layer and sequence interval.

At onset, shale volume content in Tajin field and total porosity in Agua Fria field are modeled. Block kriging, trend model, and conditional thickness-weighted Bayesian scheme are presented for the integration of data types and data scales. Facies distributions in Tajin are modeled by indicator kriging conditioned to Vsh content, and hence to seismic. Porosity distributions are by sGsim collocated with Vsh for each facies group, and water saturation distributions are collocated with porosity. Permeability distributions are function of porosity, water saturation, facies and sub-sequences. In Agua Fria, effective porosity and facies are by p-field related methods. Patterns of sand continuity and pay sand connectivity are derived and uncertainty in their prediction is evaluated.
Modeling Facies Bodies and Petrophysical Trends in Turbidite Reservoirs
Authors: Hauge R. , Syversveen A. R. , MacDonald A. C.
Published: December 2007

A two-stage approach for modeling turbidite reservoirs is presented. The first stage is to model the distribution and geometry of turbidite sandbodies using an object model that can be constrained to local vector directions. The facies objects are individual turbidite sandbodies that are locally aligned to a vector parameter to model the effect of local seafloor topography on sandbody geometry and orientation.

The second stage involves modeling petrophysical variation within each turbidite body. This is done by using a variety of intrabody trends, which describe vertical and lateral variation in the petrophysical properties. These variations are the result of grain-size and sorting trends within each turbidite sandbody.
Developing a Risk Assessment and Situation Response Program for Crisis Events
Authors: Butler Rindos Vickie L.
Published: December 2007

Many organizations believe the type of crises appearing in the daily press will never happen to them. They rarely appreciate the impact a crisis can have upon the lives of employees, the company, or its products/services. Moreover, they fail to see just how vulnerable they are - even when risk is staring them in the face. ‘Crisis’ costs seldom appear on the bottom line of the budget - until the enormous recovery costs must be added to the balance sheet as an expensive post-script. The early hours of any incident are critical to its outcome and timely, preventive actions pay dividends that can make the difference for financial recovery. The prepared organization recognizes potential enemies, knows possible strike areas, and is proactive in defense. This paper will address a risk assessment, the development of a flexible Situation Response Program (SRP) for various crisis events, and after-crisis activities for companies that provide services to the petrol-chemical industry. It will include crisis events not generally identified in Health and Safety Procedures that deal with fires, injuries, weather, etc.
Leadership for Safety Excellence: The "Passion" and "Relentless Follow-Up" Needed for Continuous Improvement
Authors: King William (Bill) T. , Artym John
Published: December 2007

Arguably, the ultimate objective of safety is injury prevention. But historically, there has been some dissension about the relative practical application of behavior and attitude in terms of real prevention of injuries, collisions and incidents. Sustaining systems of injury prevention need to be based on stimulating individual decisions that heightened awareness about individual attitudinal, attentional, and behavioral control. Leadership for Safety Excellence (LSE) is a process to sustain the "passion" and "relentless follow-up" needed for continuous improvement of health, safety and environmental systems. LSE is a way to use forward thinking and leading indicators to impact every aspect of Health, Safety and Environmental (HSE) related activities in the workplace. The LSE process enables everyone to make proactive preventive decisions daily on the job, on the way to/from work, and at home.
Self-Learning Reservoir Management
Authors: Saputelli L. , Nikolaou M. , Economides M. J.
Published: December 2007

In this work, we present an industrial automation framework for control and optimization of hydrocarbon producing fields while satisfying business and physical constraints.

The all-encompassing reservoir management problem is decomposed into a series of different-time-scales optimization exercises. A model predictive control strategy is used to regulate well and field instrumentation. The optimum field operating point, which changes with time, satisfies the maximum economic return.

The work is a starting point for further development in automatic intelligent reservoir technologies.
Gas Cycling and the Development of Miscibility in Condensate Reservoirs
Authors: Jessen K. , Orr F. M.
Published: December 2007

This paper presents a detailed analysis of the development of miscibility during gas cycling in condensates and the formation of condensate banks at the leading edge of the displacement front.

Dispersion-free, semi-analytical one-dimensional (1D) calculations are presented for enhanced condensate recovery by gas injection. The semi-analytical approach allows investigation of the possible formation of condensate banks (often at saturations that exceed the residual liquid saturation) and also allows fast screening of optimal injection gas compositions. We describe construction of the semi-analytical solutions, a process which differs in some ways from related displacements for oil systems.

We use an analysis of key equilibrium tie lines that are part of the displacement composition path to demonstrate that the mechanism controlling the development of miscibility in gas condensates may vary from first-contact miscible drives to pure vaporizing and combined vaporizing/condensing drives. Depending on the compositions of the condensate and the injected gas, multicontact miscibility can develop at the dew point pressure, or below the dew point pressure of the reservoir fluid mixture.

Finally, we discuss the possible impact on performance prediction of the formation of a mobile condensate bank at the displacement front in near-miscible gas cycling/injection schemes.
Application of Convolution Theory for Solving Non-Linear Flow Problems: Gas Flow Systems
Authors: Mireles T. J. , Blasingame T. A.
Published: December 2007

In this paper we present the development of a rigorous approach for the solution of non-linear partial differential equations by use of the Laplace transformation — in particular, the convolution theorem for Laplace transforms. While the rigor of this new approach is general, our paper is devoted to the development, verification, and application of this method for the case of real gas flow in porous media. This paper focuses on verification of real gas flow solutions using the results of numerical simulation.

The major results of this work are: Development of a general analytical approach in the Laplace domain for solving non-linear partial differential equations.Verification and application of this new approach for the flow of a real gas in porous media.

We observe excellent agreement between the numerical and analytical results for the case of a single well produced at a constant rate in a closed reservoir. We conclude that this approach could be adopted as a method of verification for numerical simulation, as well as for analytical modelling of the gas flow case — in particular, for modelling future performance directly and accurately, without numerical simulation or some weak approximation (p or p2 approximations, etc.).

In addition to the specific problem considered in this work, the flow of a real gas in porous media, we believe that it may be possible to extend this work for the development of analytical solutions for multiphase flow.
Toe-To-Heel Waterflooding. Part II: 3D Laboratory Test Results
Authors: Turta Alex , Goldman Jon , Singhal Ashok , Zhao Litong
Published: December 2007

A new waterflooding process, Toe-To-Heel Waterflooding (TTHW) was developed, partly based on recently developed thermal toe-to-heel displacement processes: THAI and CAPRI. TTHW is a novel oil recovery process utilizing a horizontal producer (HP) and a vertical injector (VI). The HP has its horizontal leg located at the top of formation, while its toe is close to the VI, which is perforated at the lower part of the formation.

TTHW realizes a gravity stable displacement, where water/oil mobility ratio becomes less important, and its detrimental effect on sweep efficiency is diminished. The main advantage of TTHW process is that the water always breaks-through at the toe, following which water cut gradually increases.

A systematic investigation of the TTHW process in a Hele Shaw laboratory model mimicking a simulated porous medium showed that the process substantially improved the vertical sweep efficiency as compared to conventional waterflooding. Following these semi-quantitative tests, a more comprehensive 3-D model testing was undertaken in order to investigate the overall sweep efficiency of the process. The 3-D model consists of a metal box filled with glass beads and saturated with oil at connate water saturation; the thickness of "oil layer" is 16 cm and the length is 42 cm. Oil was displaced with a high salinity brine, either in a toe-to-heel configuration, or in a conventional array, using only vertical wells.

A staggered line drive was used, by injecting water in two vertical wells located at one side of box and producing oil through either a horizontal producer with its toe close to injection line, or by using a vertical producer located at the horizontal producer's heel position.

Several TTHW tests were carried out at different injection rates. For a given injection rate, the TTHW results were compared to those of conventional waterflooding tests. For the same amount of water injected, the ultimate oil recovery increased by a factor of up to two, as compared to that for conventional waterflooding. Numerical simulation models successfully matched the observed performance in the laboratory.

All in all, the results of laboratory investigations and numerical simulations show that the novel TTHW process is sound, and can be further optimized.
Water Injection Optimization Using a Streamline-Based Workflow
Authors: Thiele Marco R. , Batycky Rod. P.
Published: December 2007

This paper describes a novel approach to optimize injection and production well rates in a waterflood using streamline-based (SL) flow simulation. The method provides engineers with an approach that is well beyond the traditional field management workflows offered by standard surveillance and finite difference (FD) simulation. The method is automated and therefore applicable to very large fields with many wells. Streamline based flow simulation is unique in that it allows to quantify the amount of injected and produced fluids between well pairs via well allocation factors (WAF's). WAF's allows calculating the efficiency of injection wells as the ratio of injected water to the oil produced at offset wells. With injection efficiencies known across the field for each injector, water can be reallocated from low-efficiency to high efficiency wells, thereby optimizing production for each barrel of water injected.
Formation Testing While Drilling, a New Era in Formation Testing
Authors: Proett Mark , Walker Mike , Welshans David , Gray Charlie
Published: December 2007

This paper introduces a new technology in which a logging while drilling (LWD) tool is used to pressure test a formation during the drilling process. The Formation Testing While Drilling (FTWD) or GeoTAP* tool described in this paper uses a testing technique similar to wireline formation testers. A probe is extended to the formation and a small sample chamber is used to pressure test the formation. The drilling environment offers many new challenges to pressure testing, however.

Wireline tools require a great deal of interaction with the engineer, which is very limited in the drilling environment. Therefore, the new tool has up-link and down-link capabilities and is highly automated for test control. New data compression routines are described that enable not only some of the raw data to be transmitted, but formation permeability (mobility) and test quality estimates to be obtained in realtime. An efficient algorithm is used down-hole to analyze the data where testing parameters and selected pressure data are transmitted to the surface in real-time for continuous monitoring of the test.

The drilling environment is more dynamic than is the case for wireline testers. This environment is modeled using a finite element simulator to show the effects these dynamics might have on pressure measurements. The results show that even in this highly dynamic state it is possible to obtain reliable pressure measurements.

Field data from the new GeoTAP tool is presented and compared with wireline formation test (WFT) data in test wells. The new tool requires the drill pipe to stop rotating/sliding for about 7 minutes per pressure test. During this time the pumps can be turned on or off. Most of the test very favorably with WFT data in terms of the absolute pressure measurement, repeatability and accuracy. The field example demonstrates the robustness of the measurement with three repeat pressure tests that were taken at three different depth points where, in each case, the pressures recorded were within 1 psi. Final conclusions are drawn regarding FTWD technology and its future direction.
Formation Pressure Testing During Drilling: Challenges and Benefits
Authors: Meister M. , Lee J. , Krueger V. , Georgi D. , Chemali R.
Published: December 2007

Formation pressure testers are utilized to measure formation pressure along a wellbore. From the data reservoir engineers develop information on formation fluid type, fluid contact depths, and formation connectivity. Together with recovered fluid samples, these data provide crucial exploration and development information for oil and gas fields. Until recently, pressure measurements were performed with wireline tools or during production and drill stem testing. Notably, these methods can only be used after the borehole is drilled and the drill string is pulled out of the hole.

A formation test-while-drilling tool has been introduced to provide formation pressures during a brief pause in the drilling. The tool is equipped with an intelligent control system to perform closed loop, controlled drawdown-buildup tests in less than 5 minutes. Individual tests are controlled and analyzed with the FRA (Formation Rate Analysis) method in real time while repeat tests are optimized based on the previous test data. The formation pressure data can be utilized directly to choose the casing points and adjust the mud weight and ECD (Effective Circulation Density), thus allowing one to increase the drilling efficiency and safely drill into high pressured zones. As with wireline tools, the data also can be used to establish fluid gradients and fluid contacts and to analyze the connectivity between reservoirs.
Analyzing Reservoir Fluid Composition In-Situ in Real Time: Case Study in a Carbonate Reservoir
Authors: Go Fujisawa , Mullins Oliver C. , Dong Chengli , Carnegie Andrew , Betancourt Soraya S. , Terabayashi Toru , Yoshida Satoko , Jaramillo Antonio R. , Haggag Mostafa
Published: December 2007

Near-infrared (NIR) spectroscopy is used to provide in-situ quantitative characterization of reservoir fluids during wireline sampling using five representative composition groupings (C1, C2–C5, C6+, CO2, and water). This information is vital for the proper execution of wireline fluid sampling jobs. Time variances of fluid compositions, along with absolute compositions, give us important clues about the phase and contamination level of the capturing samples in real time. In addition, quantitative compositional analysis during wireline sampling provides immediate identification of the critical fluid issues, thereby enabling optimization of the sample acquisition program. Laboratory pressure-volume-temperature (PVT) analysis requires samples that are captured in single phase and are relatively free from mud filtrate contamination. Such information is essential for reservoir management and flow simulation modeling.

This paper consists of three parts. The first part covers laboratory NIR spectroscopic study of petroleum fluids at elevated pressures and temperatures. This extensive database, coupled with principal components regression (PCR) technique, establishes the feasibility of such an in-situ compositional analysis.

The second part reports shop test results on a downhole experimental prototype. The tool estimates density for each composition group for more than 10 live fluids at conditions simulating a petroleum reservoir. Typically, the measured mass fraction for each composition group agrees with the mass fraction acquired from PVT analysis within ±5% accuracy.

The final part presents a field test case study conducted in an onshore carbonate reservoir in the United Arab Emirates (UAE). A gas injection pilot has been running for years, and a comprehensive monitoring program is in place. The first field trial of the subject technology in an observation well successfully identified the presence of injected gas, as determined by fluid compositions. This result was later found to be in good agreement with laboratory PVT analysis.
High Power/High Frequency Acoustic Stimulation – A Novel and Effective Wellbore Stimulation Technology
Authors: Wong Sau-Wai , van der Bas Fred , Zuiderwijk Pedro , Birchak Bob , Han Wei , Yoo Kwang , van Batenburg Diederik
Published: December 2007

Reduced production is often caused by local impairment of the formation permeability due to the interaction of the reservoir with drilling and completion fluids. The problem may be further compounded by impairment caused by fines migration during production.

High frequency sonic and ultrasonic waves have been used in many industrial applications to remove contaminants like dirt, oil, and grease from parts immersed in fluids. An obvious extension of this application is the removal of wellbore impairment by exposing it to high frequency acoustic waves. The influence of high frequency waves is limited to the near wellbore environment due to high attenuation. Dedicated experiments under realistic downhole conditions have been carried out in both linear as well as radial configurations. We have examined the acoustic power needed to remove near wellbore formation damage due to fines and particles plugging and drilling induced damage. Specific issues related to well completion and envelope of acoustic stimulation are presented. The laboratory results have led to the design and construction of a slim, high power and high frequency (above 10 kHz) downhole acoustic tool for field deployment.

This paper outlines the concept and presents key experimental results to support the claim. Key features of a prototype downhole tool are described.
Improvement Processes for Coalbed Natural Gas Completion and Stimulation
Authors: Olsen T. N. , Brenize Galen , Frenzel Taryn
Published: December 2007

Drilling activity to access natural gas production from coalbeds has increased dramatically in the past decade; however, the percentage of methane that has been converted to economically recoverable reserves remains only a fraction of the potential gas in place. One of the methods widely used to access natural gas from deeper, lower-permeability coal seams, has been with propped hydraulic fracture completions in vertical wellbores. Propped hydraulic fracture completions have been successful in stimulating production from conventional reservoirs from microdarcy to darcy rocks. Effective fracture lengths in excess of 1,000 ft have been documented from pressure transient analysis with skin effects as low as −6.5. Propped hydraulic fracture completions in coalbed natural gas wells have been successful in stimulating production, but have generally under performed the stimulation effects that are observed in conventional sandstone reservoirs. In spite of the fact that coal seam fracture stimulation volumes can be 3,000 to 12,000 lbm/ft of coal, effective fracture lengths are rarely documented beyond 200 ft, and post-fracture skins have been measured near zero or even positive in some cases. It can easily be estimated that if fracturing in coal seams could be brought up to parity with sandstone fracture stimulation, the recoverable reserves from coal seams could be tripled over today's standards.

This paper investigates three processes in coalbed fracturing that can inhibit stimulation effects and offers solutions that can increase coal stimulation efficiency. The effects of maximum horizontal stress azimuth in relation to cleat orientationPropped fracture placement efficiencyThe effects of fracturing fluid damage in coal cleats
Environmentally Favorable Terpene Solvents Find Diverse Applications in Stimulation, Sand Control and Cementing Operations
Authors: Curtis James
Published: December 2007

Environmental regulations on the usage of toxic aromatic solvents such as xylene and toluene are becoming increasingly restrictive. Yet, whenever organic deposits are encountered, an effective solvent is still needed to achieve a successful completion or workover. Clearly, an environmentally favorable replacement for aromatic solvents is required.

Terpenes are a renewable resource derived from plant products such as orange peels and resinous pine sap. They have been used for years in many industries in diverse applications. Compared to aromatic solvents, terpenes have good solvency and are biodegradable, less toxic and less flammable.

This paper reviews how terpene solvent mixtures have been used over the last several years in a multitude of oilfield applications, including wellbore cleanouts, matrix stimulation, hydraulic fracture stimulation, sand control, and cementing operations. It is described how in several operating areas, aromatic solvent usage has been completely eliminated in favor of terpene solvent blends.