bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategies for Reducing Oil Field Electric Power Costs in a Deregulated Market
Authors: Stiles Robert F. , Slezak M. Steven
Published: December 2007

The cost of electricity is one of the single largest items associated with oil and gas production. This cost however tends to be overlooked relative to other production costs, due to the regulated nature of the utilities combined with its specialized and non-core technical requirements. In spite of this, several studies and strategies over the years have looked at ways of reducing this cost component with meaningful results. Many of these strategies consist of structuring loads and designing equipment to take advantage of the utilities regulated rate structure. As the electricity industry in the US moves towards deregulation, these rate structures will no longer exist and in their place will be contracts negotiated on a free market basis between the user and supplier(s) of electricity.

In the upcoming deregulated electricity market, three key strategies are available to effectively manage oilfield power costs; 1) real time monitoring and control of the electrical load 2) in-field generation of electricity and 3) negotiation of an integrated power supply agreement. Because electricity is the ultimate just-in-time product, prices vary greatly depending upon when the power is consumed. The strategies listed above allow for the user to proactively structure their power supply systems to address the fundamental volatility of the real price of electricity. The effect is to strip out the historic premium that is paid to the utility to handle the natural volatility of electricity prices by blending load shifting, internal generation and market purchases.

This paper examines different scenarios where the above strategies are proposed and makes estimates for potential cost savings. These solutions utilize existing technology applied to the changing market environment and therefore focus on economic justification as opposed to technology verification. In one such case the pumping intervals for a collection of wells is adjusted using real time power prices combined with remote operations. This has the effect of reducing the total cost of the electricity consumed per barrel of production while only marginally reducing the actual number of barrels produced.
Pressure Fall-Off Analysis in Water Injection Wells Using the Tiab's Direct Synthesis Technique
Authors: Jokhio Sarfraz A. , Tiab Djebbar , Abdessalam Hadjaz , Escobar Freddy H.
Published: December 2007

Numerous waterflooding projects are under way throughout the world for increased recovery. Water injection tests of oil zones are frequently undertaken during the planning phase of waterfloods. Analysis of the bottomhole pressure data recorded during these tests not only provides similar information to that obtained from production tests concerning the well and the reservoir characteristics but also allows the mobility ratio between the injected and resident fluids to be determined.

Conventionally, pressure fall-off test data is analyzed using semilog plot of bottomhole pressure versus time. This paper is the extension of the Tiab’s Direct Synthesis Technique10-15 to pressure injection and Fall-off tests in water injection wells.

Direct synthesis is a transient pressure analysis technique10- 15, which uses log-log plot of pressure and pressure derivative vs. time. Thus, different straight line portions indicating different flow regions are directly analyzed. Direct synthesis is very useful in conditions of short and early time pressure data missing tests. It also verifies the results since it uses more than one equation for the estimation of reservoir parameters such as permeability, wellbore storage coefficient, and skin factor.

Finally, field examples of pressure falloff analysis are presented to illustrate use the direct synthesis and results are compared with those from type curves and conventional semilog analysis.
Optimizing Field Performance Using Reservoir Modeling and Simulation
Authors: Naguib Mohamed A. , Aziz Khaled A. , Hussein Ahmed
Published: December 2007

Ras Budran field is a massive Nubian sandstone reservoir compartmentalized by major faults acting as partial barriers. Vertical communication is impeded by hydraulically sealing shale layers in the development of three main pressure regimes. A combined water injection and aquifer support the pressure. Pre-mature water breakthrough has been occurred in the middle of oil leg, which in turn limit the corrective action of the isolation of the watered out zones.

3D- geological and reservoir simulation model was constructed, based upon new reservoir characterization with the objective of improving the vertical definitions within the reservoir. The reservoir properties generated by deterministic interpretation for the new micro-zones.

This paper presents the approach taken to match 17 years of production data in particular, via aquifer definition and fault communication.

The history-matched model was then used to confidently check the production and injection well pattern and performance. The matched model then used to investigate the viability of infill wells to improve drainage pattern and sweep efficiency meanwhile increasing ultimate recovery.
The Role of 3-D Seismic in a Challenging Horizontal Drilling Environment: The Cerro Negro Experience
Authors: Zubizarreta J. , Robertson G. , Adame J.
Published: December 2007

Cerro Negro is a heavy oil strategic association, located in the eastern portion of the ‘Orinoco Heavy Oil Belt’, of Venezuela. The 700-feet thick reservoir sands are assigned to the early and middle Miocene Morichal Member of the Oficina Formation. The Morichal is a transgressive fluvial to estuarine and marine sedimentary sequence, and is informally divided in to Lower, Middle and Upper units. Sands were deposited in valley fairways and show a high degree of lateral variability. This stratigraphic variability has an important impact on the seismic response. This reponse, or acoustic impedance, is directly proportional to the density and velocity differences of the lithological units. Most of the seismic impedance contrast in Cerro Negro is caused by ‘tuning effects’, due to thickness variations of the reservoir units. The use of the seismic data was instrumental for deciphering the complex relationships in the reservoir, and designing a 121 horizontal well drilling program. The integrated team approach, and the use all the well and seismic data available, was critical in the success of the first phase of the project.
Analyzing Flowing Production Data with Standard Pressure Transient Methods
Authors: Hager C. J. , Jones J. R.
Published: December 2007

Interpretation of pressure transient data using the derivative curve has proven to be an effective method for quantifying and qualifying well/reservoir information. Analyzing pressure response data affected by multiple rate changes is well understood and readily done using this standard approach. Daily production data (Time-Rate-Pressure) adheres to the same physics and theoretical description as standard multi-rate drawdown data. Therefore, this form of data can be analyzed in a similar manner.

This paper shows that the multiple flow rates and pressures forming production data can be transformed into an equivalent single rate data set for direct analysis using standard methods based on the associated derivative curve. The transformation requires nothing more than careful superposition and the calculation of the normal radial flow derivative curve. We show that this approach avoids two of the biggest difficulties with using rate-time type curves for the analysis of production data: the lack of methods for determining the regions in the data representing the proper flow regimes to apply the appropriate analysis, and the calculation of the correct pseudoequivalent production time function. A method for incorporating a derivative smoothing technique is included to improve the ability to interpret field data, which can often be erratic and difficult to analyze. After a brief presentation of the necessary theory, the applicability of this approach using both simulated examples and field data will be demonstrated.
Pressure Analysis for a Well Intersected by a Hydraulic Fracture with Multiple Segments
Authors: Escobar Freddy H. , Tiab Djebbar , Jokhio Sarfraz A.
Published: December 2007

This paper investigates the effect of multi-branched hydraulic fracture on transient pressure response of the well. Pressure transient analysis usually considers the fracture to be singleplanar surface in the rock. However, hydraulic fractures may have branches or segments which are originated at different positions along the main fracture or even starting at the wellbore (far field or near the wellbore).

A mathematical formulation intended to simulate certain fracture segmentation pattern in defferent directions is proposed assuming constant width and infinite conductivity fracture. The effect of conductivity contrast between the fractures has also been studied. The solution was obtained numerically by using an implicit formulation with the finite-difference method.

It was observed that the pressure response of a vertically fractured well with segmented fractures is very similar to the one of a well with a single fracture. A well with multiple fracture reflects the pressure behavior of a single fracture with an average conductivity. Therefore, the branched fracture does not show any recognizable/identifiable pattern in neither the pressure derivative nor the second pressure derivative curves.

Thus, it is implied that the fracture communication amongst branched network is instantaneous for infinite-conductivity fractures. Therefore, from well test data it is not possible to detect the presence of fracture branches in a reservoir. However, when the branched fracture has less conductivity than the main fracture body, the pressure response behaves like that of a well with single fracture of an average conductivity. The observed pressure pattern is the same for the case of equal fracture conductivities but a higher pressure drop is observed as the branched fracture conductivity is reduced.
China's Petroleum Industry - An Expanding Market For Equipment Suppliers?
Authors: Speltz Paul
Published: December 2007

The basic intent of this presentation is to provide the audience with a status report on the Petroleum Industry of the People's Republic of China. There are currently many misconceptions about China's ability to locate and produce her own crude oil and gas. This report will hopefully serve produce her own crude oil and gas. This report will hopefully serve as an attempt to help clarify some of these misunderstandings. The presentation will cover the recent history of oilfield development in presentation will cover the recent history of oilfield development in China-1950s to 1977. Current known oilfields with characteristics of the fields will also be discussed. The report shag also cover in some detail the current state of the art of China's programs in Seismic Exploration, Drilling, Production and Transportation both onshore and offshore and how she is combining her own technology/products with selected foreign technology. A general introduction and discussion on how one should approach marketing products in China will also be covered.History of PRC oilfield developmentPRC Net Importer Position up through 50'sSoviet Technology/Assistance through 1960PRC Self Development Program emphasizing Taching (use of maps 1949 - 1960 - 1977 throughout)Current known information - on China's fields 1. Use of maps - Discussion of Taching, Shengli and other major oil and gas fields. Discussions on characteristics of crude at each location 2. Suspected fields under developmentChina's petroleum industry - organizationUse of Chart - Discussion of organizational layout of entire organization from Peking down to local areas.China's current state of the art on:Seismic - use of own equipment, foreign purchases, methodology, projections for future a) Onshore b) OffshoreExploration and drilling - use of own equipment, foreign purchases. methodology, projections for future a) Onshore b) OffshoreProduction -use of own equipment, foreign purchases. methodology, projections for future a) Onshore b) OffshoreTransportation of crude/gas - current problems, programs, methodology, changing programs a) Onshore b) OffshoreChina's current capabilities/plans 1. Outlining/reviewing current capabilities and how they affect potential purchases of foreign equipment now and in the future - both onshore and offshore ie: What may be neededMarketing into the People's Republic of China 1. Organizational structure of foreign trade organizations (Chart) 2. Map out responsibilities of each F.T.O. 3. Role of F.T.O. and endusers 4. Approach to PRC a) Technical information b) Sales dam c) Quotation requests d) Selling in Canton e) Selling in Peking g) Trade exhibitions
Development and Application of a New Roller Cone Bit with Optimized Tooth Orientation
Authors: Chen S. L. , Dahlem Jim , Dennis John
Published: December 2007

Based on computer drilling simulation results, a new, unique roller cone bit has been developed1. All the teeth on this new bit are oriented optimally such that the leading face of the elongated crest of a tooth is perpendicular to its trajectory during interaction with a formation. This paper describes the computer model, the calculation procedure for determining the trajectories of the teeth, and the method for designing the new bit. Laboratory and field tests have shown that the new bits drill up to 25% faster and longer than the same type of bits with conventional tooth design.
Heavy Oil Recovery in Potiguar Basin, Brazil: Steamflooding from Field Pilot Testing to Commercial Application
Authors: Mezzomo Roberto F. , Dutra Tarcilio V. , de Miranda-Filho Daniel N. , de Paula Armando L. , Cursino Delson F. S.
Published: December 2007

Northeastern Brazil, in the fields of Fazenda Belém, Estreito and Alto do Rodrigues. Shortly after discovery, they were stepwise and successfully put into production through steam cycling. However, upon trying to convert this operation to steamflooding via two field pilots in selected areas of Fazenda Belém and Alto do Rodrigues, where cycling had reached the economic limit, the results left much to be desired. The operation was suspended and production maintained by the original steamcycling program by expanding it into new areas of the fields.

Based on the fact that the two steamflooding field pilot attempts were on patterns of 5 and 2½ acres, respectively, it was thought that reservoir heterogeneity, among other issues, could be responsible for the two consecutive failures. Consequently, a third pilot was decided upon, this time in a specific area of Estreito. Some 1,600 MMB of 15-16ºAPI OOIP were discovered in the early eighties, onshore Potiguar Basin, field. New wells were drilled for this purpose, defining four adjacent and inverted nine-spot patterns of 1¼ acre each.

It was the year of 1993, when a project was approved in the portfolio of PRAVAP-Petrobras Strategic Advanced Oil Recovery Program, to design and implement the Estreito steamflooding pilot test, together with other related lines of research focused on the heavy oil accumulations in Potiguar Basin. Five years, 32,000 man-hours, and US$2.3 million later, the results were so encouraging that prompted the decision by the Operational Unit to initiate the corresponding study to scale-up the pilot test not only to the entire Estreito field but also to the neighboring, Alto do Rodrigues. In addition, this enterprise took into consideration the installation of a gas fired thermoelectric plant for the co-generation of steam and electricity, as to enhance the economic feasibility potential.

This paper presents the results of the PRAVAP project, as well as the production forecasts for the ongoing effort to expand the steamfloding operation to the commercial scale in those two fields.
Well Deliverability of Undersaturated Coalbed Reservoir
Authors: Thungsuntonkhun Witsarut , Engler Thomas W.
Published: December 2007

The production mechanism of gas from a coal reservoir is different from conventional gas reservoirs. For example, a typical coalbed reservoir first produces water until reservoir pressure decreases below the desorption pressure at which time gas begins producing. Furthermore, as gas is desorbing, the matrix shrinks and reservoir permeability changes with time. Due to these dissimilarities the conventional method to calculate the inflow performance curve cannot be applied to coal reservoir.

This paper presents a method to calculate the Inflow Performance Relationship (IPR) curve for undersaturated coal gas system based on a Fetkovich-type approach. A new concept to predict the coal gas inflow performance includes matrix shrinkage effects for the entire production sequence. The production sequence is divided into three parts in response to the production mechanism of coal reservoirs. In the first part, the IPR for water is calculated as single-phase production. Followed by multiphase production of water and gas. Last the third part is single-phase gas production. Previous work, considered this stage as single-phase gas production like a conventional gas reservoir; however, this work demonstrates permeability increases at lower reservoir pressure resulting in an increasing production rate for given well bore flowing pressure (Pwf).

Several field examples were evaluated with this new method, Deerlick Creek Field in Black Warrior Basin, and Cedar Hill Field in Fruitland Coal San Juan Basin. In both examples, an improved match of IPR data was achieved. Subsequently, a better prediction of well performance is proposed for undersaturated coalbed methane reservoirs.
Stimulating Oil and Gas Wells With PGDBK Gas Generators
Authors: Banahene A. O. , Pepe D. C. , Lueck W. R.
Published: December 2007

PGDBK Technology is used for the stimulation of oil and gas wells to enhance productivity. The pulsating pressure generated upon combustion of caseless cylindrical powdered charges overcomes the tensile strength of formation rock to create multiple fractures1. These fractures, with horizontal and vertical orientation, extend more than 100 feet in diameter from the wellbore. Combustion of PGDBK generators takes place near a selected pay zone in a well under a hydrostatic column sustained by a tamp fluid.

Through a combined effect of mechanical, thermal, and chemical actions, the use of PGDBK increases pressure communication between the extended reservoir and the wellbore. The pressure pulsating action of generated non-combustible gases erodes fracture walls keeping the flow channels opened for a long period of time without propping agents. High temperature generated through the combustion process cleans the wellbore region of heavy hydrocarbons, reduce the viscosity of oil and enhance relative permeability of oil to water. Additional oil is also recovered through the reduction of the surface tension by the chemical actions of the combustion products.

The in-situ process ends with a negative pressure gradient towards to the wellbore, washing impediments from flow channels. Wells are immediately swabbed or circulated to remove debris, equipment re-installed, and well brought back on line.

This paper describes the PGDBK stimulation technology. It further presents case studies of successful field applications in three different USA sedimentary basins in the summer of 2000 and recent treatments in Russia.
Resolving Differences Between Core and Welltest Permeability in Basal Colorado Sandstones, Canada: The Role of Rock Heterogeneity, Relative Permeability and Formation Damage
Authors: Potocki Dan
Published: December 2007

Welltest permeabilities are about 1 to 3 orders of magnitude lower than average core permeabilities from the same well for gas bearing Cretaceous Basal Colorado channel sandstones in south-eastern Alberta, Canada. The large differences coupled with local anomalously poor production from rock with high core permeabilities have raised uncertainty in both geologic and engineering communities regarding the reliability and representativeness of welltest and core permeabilities, respectively. Differences between core and welltest permeabilities are related to the core analyses, sampling and averaging techniques, and welltest interpretation procedures. Core absolute permeabilities are optimistic in part due to the effects of clay dehydration, rock decompaction, biased oversampling of high permeability intervals, and absence of relative permeability effects. Welltest effective permeabilities have been underestimated for gas wells producing minor amounts of water by wrongly assuming single phase gas flow in permeability calculations. The sum of these features creates the large differences between core and welltest permeability.
Streamline-based Production Data Integration Under Changing Field Conditions
Authors: He Zhong , Datta-Gupta Akhil , Yoon Seongsik
Published: December 2007

Recently streamline-based flow simulation models have offered significant potential in integrating dynamic data into high-resolution reservoir models. A unique feature of the streamline-based production data integration has been the concept of a ‘travel time’ match that is analogous to seismic tomography and has allowed the use of efficient and proven techniques from geophysics. In this paper we propose a ‘generalized travel time’ inversion method for production data integration that is particularly well-suited for large-scale field applications with changing conditions. Instead of matching the production data directly, we minimize a ‘travel time shift’ derived by maximizing a cross-correlation between the observed and computed production response at each well. There are several advantages with our proposed method. First, it is general and extremely computationally efficient. The travel time sensitivities can be computed analytically using a single streamline simulation that can be orders of magnitude faster than a conventional reservoir simulator. Second, it is very robust and the minimization is relatively insensitive to the choice of the initial model. Finally, it is field-proven because we utilize efficient techniques from geophysical inverse theory.

We demonstrate the power and utility of our proposed method using synthetic and field examples. The synthetic examples include a large-scale 3D example with quarter-million grid cells involving infill drilling and pattern conversions. The field example is from the Goldsmith San Andres Unit (GSAU) in West Texas and includes multiple patterns with 11 injectors and 31 producers. Starting with a reservoir model based on well log and seismic data, we integrate water-cut history for 20 years in less than 2 hours in a PC.
Characterization of West-Africa Submarine Channel Reservoirs: A Neural Network Based Approach to Integration of Seismic Data
Authors: Arpat B. G. , Caers J. , Haas A.
Published: December 2007

Advances in deep water drilling technology have cleared the path for new domains of hydrocarbon exploration along the Atlantic margins. Such deep marine settings are generally characterized utilizing seismic data while in development phase. Yet, interpreting facies information from seismic amplitude data requires an extensive and tedious work of an expert geologist/geophysicist. This process is not only costly in terms of work hours but also invites human inconsistencies into interpretations. This paper attempts to solve the above problem by proposing a neural network based automation method that learns how to relate the seismic data to facies objects like channels. The neural net training is based on the manual/CAD interpretation of a small portion of the available seismic amplitude data by an expert geologist/geophysicist. The trained neural net is shown to be able to automatically detect channel body features in the remaining portion of the data. As the case study, the paper includes a West-Africa submarine channel reservoir where the expert interprets a seismic amplitude data set of a turbidite sequence and where the neural network manages to estimate channel facies morphologies from seismic data.
Improved Reservoir Characterization of a Mature Field through an Integrated MultiDisciplinary Approach. LL-04 Reservoir, Tia Juana Field, Venezuela
Authors: Márquez L. J. , Gonzalez M. , Gamble S. , Gomez E. , Vivas M. A. , Bressler H. M. , Jones L. S. , Ali S. M. , Forrest G. S.
Published: December 2007

The LL-04 reservoir is located in the northeastern section of Lake Maracaibo and is part of the prolific Bolivar Coastal Field (BCF). Since its discovery in the late 1920's, this reservoir has produced over 520 MMSTB of oil from shallow (<3000 feet), unconsolidated fluvial and fluvial deltaic sandstones of the Miocene Lagunillas and La Rosa formations. Production is complicated by the heterogeneous nature of the sediments, low oil gravity (12° - 19° API) and water coning and channeling. A multidisciplinary team consisting of engineers, geologists, geophysicists and petrophysicists was assembled to characterize and simulate the field. The objective of the team was to develop a reservoir management plan for the LL-04 Field that would increase daily production and ultimate recovery. Available data included 3-D seismic, openhole logs from over 600 wells, four cores and production and pressure measurements. All available data were used and honored in the interpretation process. Pressure measurements and production history were integrated with the seismic interpretation, log analysis, core descriptions, log correlations and deterministic mapping to define the reservoir compartments. Seven reservoir regions were defined. The original oil in place (OOIP) was increased by 44% as a result of this rigorous study. Also, 80 workover/recompletion candidates and 25 areas for infill drilling were identified.
Optimization of Rates of Penetration in Deepwater Drilling: Identifying the Limits
Authors: Hemphill T. , Murphy B. , Mix K.
Published: December 2007

Deepwater drilling in the U.S. Gulf of Mexico [GOM] is usually characterized by very narrow pore pressure / formation fracture gradient [PP / FG] windows. In GOM deepwater drilling, firm control over Equivalent Circulating Density [ECD] is required to help ensure these fracture gradients are not exceeded to reduce lost circulation and minimize expensive non-productive rig time. With the high daily operational cost of deepwater drilling, operators are pushed to drill as fast as possible, yet maintain a stable borehole and remain within the pressure bounds of their particular drilling situation. For these reasons synthetic-based drilling fluids [SBM] are commonly used.

Occasional hole pack-offs of large cuttings around the BHA during connections precipitated a study by the operator and drilling fluids service provider to thoroughly study the problem and recommend courses of action to help improve hole cleaning efficiency and optimize drilling operations. With the calculations of hole cleaning efficiency levels for various cases studied, accurate ECD predictions were made, and safe operating windows in terms of ROP were identified. These results were then applied on 2 GOM deepwater wells drilled with SBM having water depths between 2800 and 8800 ft. In this paper, the hydraulic studies and the field results are described and recommendations for future deepwater drilling operations are offered.
Demonstrations of Real-Time Borehole Seismic from an LWD Tool
Authors: Underhill W. , Esmersoy C. , Hawthorn A. , Hashem M. , Hendrickson J. , Scheibel J.
Published: December 2007

A new technique provides conventional borehole seismic measurements in real time while a well is being drilled. The system consists of a logging-while-drilling (LWD) tool with seismic sensors positioned near the drill bit, a seismic source at the surface, and a measurement-while-drilling (MWD) system for real-time telemetry. The seismic source is fired during pipe connections, seismic data are processed downhole and check-shot information is sent to the surface.

Borehole seismic tools conveyed by wireline cable have been used for a variety of applications including seismic time-depth mapping, and reflection and transmission imaging of subsurface structures. Although wireline borehole seismic services are mature, they are unable to provide all the benefits that are sought in real time while drilling. This is particularly the case when borehole seismic surveys are conducted to help make drilling and well construction decisions, such as steering and deciding on casing and coring points. The new service provides standard borehole seismic information in real time that can be exploited for drilling optimization, cost savings, and safety improvements. Check-shot (time/depth) data are used to place the bit on the seismic map to help well navigation and casing point selection and to avoid drilling hazards, such as pore pressure, seen on the seismic. Real-time seismic velocities can be used to update pore-pressure predictions from surface seismic. Ultimately, the real-time velocities will be combined with look-ahead images, formed from the seismic reflections from horizons ahead of the bit, to provide a direct measurement of the distance to a marker of interest.

In 2000, a field-test campaign conducted with experimental tools in the Gulf of Mexico demonstrated the first known real-time check-shot technique with an LWD tool. We will show the results and further describe the status of the service.
Early Kick Detection for Deepwater Drilling: New Probabilistic Methods Applied in the Field
Authors: Hargreaves David , Jardine Stuart , Jeffryes Ben
Published: December 2007

This paper documents the development and field test of a sensitive new kick detection system. The detector uses a Bayesian probabilistic framework to make good decisions based upon noisy drilling data. It works on any rig type, but brings particular improvements to kick monitoring for deepwater drilling, especially in high heave conditions. The approach offers sensitivity improvements over existing systems, while maintaining a low false alarm rate.
Effects of Fluid Flow in a Porous Cuttings-Bed on Cuttings Transport Efficiency and Hydraulics
Authors: Cho Hyun , Shah Subhash N. , Osisanya Samuel O.
Published: December 2007

The study of effective cuttings transport and accurate prediction of drilling hydraulics has been a major concern for decades in the drilling industry. It is inevitable for deviated wells and long horizontal wells to have a considerable amount of cuttings-bed in the annuli. Common problems with most of the existing models are that they do not consider the drilling fluid flow through a cuttings-bed.

A new mathematical model is proposed to identify the effects of fluid flow in porous cuttings-bed and the differences of relative velocities between cuttings and carrier fluid on drilling hydraulics. The carrier fluid flows through the cuttings-bed, forming a porous matrix in which porous media itself is moving or stationary depending on the force balances. This model also considers the pressure losses of carrier fluid flowing through porous media in a cuttings bed layer. This paper specifically describes the model development (including changes in axial forces in continuity and momentum equations due to changes in a deviated well angle), the solution, and simulation results. In order to ensure a comprehensive understanding of the effects of parameters affecting cuttings transport efficiency, a simulation of the hole cleaning mode is performed. This study provides a method to predict cuttings transport efficiency accurately, and to precisely estimate friction pressure losses in deviated wells (hole deviation angle: 30 to 60°), which have the most unstable cuttings bed characteristics.
Gas Hydrate Formation in Drilling Mud Characterized With DSC Technique
Authors: Herzhaft Benjamin , Dalmazzone Christine
Published: December 2007

Gas hydrates have been studied by petroleum industry for more than 60 years, but up to now, the major part of the research was linked to the problem of oil transportation, prevention or remediation of pipe lines plugging. The development of deep offshore drilling has extended gas hydrate problem to drilling muds area. The consequences of hydrate formation in drilling muds can be dramatic: loss of mud rheological properties, accumulation of hydrate crystals leading to plugging of the lines, the BOP or the annular, interruption of the drilling operations and even destruction of rig equipment. To prevent these problems, operators must use drilling muds (WBM or OBM) with thermodynamic inhibitors of hydrate formation as salts and glycols, which cause important problems of density adjustment, corrosion and toxicity. The usual way to determine the thermodynamic conditions of hydrate formation in drilling mud formulations is to use batch reactors or thermodynamic models validated from PVT experiments on simple or model fluids.

An innovative methodology was elaborated using Differential Scanning Calorimetry (DSC) to determine the thermodynamic equilibrium properties and kinetics of hydrate formation in mud formulations, particularly in the presence of large amounts of mineral. This technique allows the measurement of heat transfers as a function of time, temperature and pressure and thus detects phase transitions. We have shown recently that this rapid, versatile, easy to use technique permits to determine the dangerous zones for hydrate appearance. We present here new results of hydrate characterization. Using DSC, hydrate appearance in several drilling muds formulations (WBM or OBM) was shown and quantified. The influence of gas composition i.e. methane or natural gas on hydrate formation has been studied for different mud continuous phases, the effectiveness of several inhibitors was measured. A methodology using isothermal experiments to quantify kinetics of the formation of hydrate was proposed, the bubbling of gas into the measuring cell allowing to simulate agitation and progressive gas incorporation. Effect of time and temperature are by this way quantified. Through this work, DSC has proven to be an efficient technique for characterizing hydrate formation in drilling muds.
Obtaining Successful Shoe Tests in the Gulf of Mexico: Critical Cementing Factors
Authors: Harris Kirk , Grayson Gary , Langlinais Joey
Published: December 2007

Approximately one out of six casing shoes in the Gulf of Mexico (GOM) require a cement squeeze job after primary cementing. Numerous theories exist regarding the causes of high shoe-test failure rates, but failure is often attributed to problems associated with the primary cementing job.

A GOM database containing information about more than 4,000 shoe-cementing operations was reviewed to find correlations between the success/failure rate and industry-accepted best cementing practices. The results confirm some correlations between the cementing process and shoe-test success; however, no single cementing parameter has an overwhelming effect on shoe failure. Of the industry-accepted best cementing practices, the GOM database shows the following factors to be most important for shoe-test success: (1) pipe movement, (2) maintenance of circulation during cementing, (3) accurate displacement volumes, (4) centralization, and (5) application of foam cementing. The cementing parameters that appear to have less effect on shoe-test outcomes were (1) mud properties, (2) displacement rates, (3) spacer volumes, and (4) application of a hesitation squeeze at the end of the primary cement job.

The review of the GOM database also showed that deeper casings are more susceptible to shoe-test failure, as are wells in deeper water. The data shows a constant rate in shoe-test failures since 1993 and a large variation in success between operators.
Chipping Resistant Polycrystalline Diamond and Carbide Composite Materials for Roller Cone Bits
Authors: Fang Z. , Griffo A. , White B. , Belnap D. , Hamilton Rob , Portwood G. , Cox P. , Hilmas G. , Bitler J.
Published: December 2007

Cemented tungsten carbide and polycrystalline diamond are the most critical materials used for roller cone bit cutting structure. Chipping and catastrophic breakage are the primary failure modes for the materials and hence the limiting factor of service life of a drill bit. Chipping and fracture resistance can be improved at the expense of hardness and wear resistance of the materials. This trade-off between wear resistance and chipping resistance hinders the development of super hard materials for demanding drilling applications. Functionally designed composite materials of polycrystalline diamond (PCD) and cemented tungsten carbide (WC-CO) that offer enhanced chipping resistance without significantly sacrificing wear resistance are studied and reported in this presentation.

Specifically, one example of the functionally designed composite materials is a honeycomb structured composite of polycrystalline diamond (PCD) and WC-Co and its application for diamond enhanced inserts for roller cone bits. The PCD/WC-Co composite takes advantages of high modulus and superior wear resistance of diamond, while it mitigates chipping and cracking using the tougher WC-Co as cell boundaries. The overall engineering properties and performance are superior to that of pure PCD.

Another example of functionally engineered hard materials is double cemented (DC) tungsten carbide. Double cemented tungsten carbide has 50% or higher fracture toughness than conventional cemented tungsten carbide at equivalent wear resistance. When compared to tool steels, DC carbide has equivalent fracture toughness but much higher wear resistance. Field tests of honeycomb structured diamond enhanced inserts (CDEI) demonstrated the controlled chipping characteristics and longer durability of components as compared to conventional homogeneous PCD materials with comparable wear resistance. DC carbide also exhibited excellent damage tolerance during field tests in demanding applications where excessive heat checking and fracturing of inserts are common failure modes.
Field Development Utilizing Rotary Steering Technology
Authors: Grini Morten , Rice Bill , Stromberg Svein
Published: December 2007

The Jotun Field is located approximately 165 kilometers offshore Norway in 127 meters of water. Jotun development drilling was executed from a wellhead platform with a fit for purpose new build drilling rig. All production wells were planned as complex directional, horizontal producers in Paleocene, Heimdal sandstones at a depth of approximately 2050 meters TVD SS.

Reservoir target complexity dictated tortuous directional well paths often resulting in azimuth changes in excess of 90 degrees at high angle, horizontal inclinations. Target tolerance ± 1m was common place at measured depths out to 6000 meters. Directional control and well tortuousity were critical well design considerations.

An agreement was reached between Esso Norge AS and Baker Hughes Inteq to utilise AutoTrak™ steering technology on all 12 1/4 inch intermediate and 8 1/2 inch horizontal hole sections on the Jotun B Platform. Drilling commenced in April 1999. This was the first field to be developed using rotary steering technology.

To date, 1 water injection well and 14 horizontal production wells have been drilled on Jotun B. This paper provides a history of drilling performance utilising rotary steerable technology on the Jotun B Platform.

The following topics are discussed: Well design considerations and complex 3-dimensional well pathsDrilling performanceAutoTrak™ tool performance and reliabilityRotary steering hole conditioning benefits
Advanced Ultrasonic Scanning Tool and Evaluation Methods Improve and Standardize Casing Inspection
Authors: Frisch G. , Mandal B.
Published: December 2007

Evaluating the inner and outer condition of casing has been problematic. Typical casing inspection logging tools such as calipers, phase-shift tools, and flux-leakage devices often have been unable to function mechanically in larger size casing. Additionally, small pipe defects can go unnoticed due to poor azimuthal resolution of the measurements or to the averaging techniques, in both casing and risers, using previous casing inspection methods.

The high horizontal (radial) and vertical sampling rates of ultrasonic devices can provide precise casing inspection for most casing sizes. Use of a navigation package permits data to be corrected for orientation and tool rotation. Data such as casing inner diameter and radius, casing ovality, and 40 to 200 caliper traces may be recorded in real time in conventional or imaging log formats, permit monitoring over time. This allows easier monitoring of the deterioration in specific regions of the casing.

With the use of risers for sub-sea trees and large casing in the deep offshore arena, the problems of pipe inspection are escalated. Riser monitoring represents one of the unique and economically important applications of this tool. Previous attempts at using conventionally configured ultrasonic scanning tools to evaluate large casing have been unsuccessful because the significant distance between the tool transducer and the casing wall causes the reflected signals to be highly attenuated and virtually unusable. Therefore, a new large-radius adjustable scanning head was developed for use with the ultrasonic scanning tool. Its inclusion allows the positioning of an ultrasonic transducer at an optimum distance from an inspection target, such as the wall of a casing or a marine riser, to provide consistent and accurate internal measurements in large-diameter casing. This tool and head combination has successfully monitored risers with an internal diameter larger than 19 ½ inches

New real-time and post processing analytical procedures correct for tool position and are required to accurately detect and measure casing wear. These processes will provide a "quality grade" for each joint of downhole casing. Improved processing software provides two- and three-dimensional images, a tabular listing of evaluation results, automatic counting of joints, and segmented data plots.

Several field logs illustrate a range of wellbore conditions and casing damage. The ultrasonic scanning tool provides both quantitative and qualitative evaluation and diagnosis of casing problems.
Extending the Influence of Real Options: Problems and Opportunities
Authors: Luehrman Timothy A.
Published: December 2007

Investments in oil and gas are subjected to increasingly sophisticated financial analyses. Real option valuation is prominent among the new financial analytical tools being applied prospectively to projects in the industry. This paper begins with the observation that many real option analyses are formally, technically correct and yet clearly lack substantial influence on decisions and ongoing project management. The paper considers possible explanations for this lack of influence, including aspects of model design and construction, organizational structure, training, and corporate communication habits. The paper explores two problems in more detail. First, the mathematically powerful assumption of optimal exercise is built into all real-option models, yet it clearly over-simplifies corporate behavior. The paper cites recent advances in corporate finance theory to show why corporations sometimes fail to exercise options optimally. These include insights from research on agency costs, information asymmetries, and corporate governance. When these problems acquire first-order significance they tend to undermine the credibility of an otherwise sound model. Second, there is a dissonance between the established language of capital budgeting (essentially cash flows and discount rates) and the language of real options, which is still evolving, but which must at a minimum accommodate changes over time in key variables and the phenomenon of active rather than passive management. The paper concludes with practical suggestions for surmounting or skirting these obstacles, drawn from the author's experience as an academic and consultant in the field of real option valuation.
General Solution for Option Analysis and Valuation Using a Branching Monte Carlo Method
Authors: Whiteside M. W. , Drown C. , Levy G.
Published: December 2007

The oil industry regularly applies decision tree analysis for the evaluation of single decisions involving discrete uncertainty. Decision processes, such as the evaluation of appraisal drilling or a flexible oilfield development, that require the resolution of continuous uncertainty and the evaluation of multiple sequential decisions, are difficult to analyse using conventional decision tree methods and require the application of alternative techniques.

This paper presents a solution to the problem using a branching Monte Carlo method that is derived from option theory. This method can be applied to a large class of problems involving an indefinite number of uncertain variables and multiple sequential decisions.

An example of the method is presented for the evaluation of a multi-well appraisal program and it is shown that this method can be used for optimal appraisal planning. The paper proposes the application of a resource learning factor, which is a measure of the resource uncertainty reduction from gaining additional information. This learning factor can be derived from historical records of many oil companies.

Further, the paper compares the active option of appraisal with the passive option of waiting for prices to increase that is more commonly considered in the option literature. It is shown that where an active resource discovery process is followed the active option dominates the passive price option.
Improving Investment Decisions Using a Stochastic Integrated Asset Model
Authors: Begg S. H. , Bratvold R. B. , Campbell J. M.
Published: December 2007

This paper addresses the need for a holistic, integrated approach to assessing the impacts of uncertainty on oil and gas investment decision-making. We argue that this cannot be accomplished effectively by just adding a capability to deal with uncertainty to classical, rigorous models of all the components that contribute to an investment decision evaluation. Further, we suggest that such an approach, if feasible, is not desirable. Instead, we propose the concept of a Stochastic Integrated Asset Model (SIAM) embedded in a decision support system. This approach involves trading-off some technical rigor for a more complete and accurate assessment of the impacts of uncertainty on the investment decision-making process. The main elements of the system are: simplified component models for each domain; Monte Carlo simulation engine; modeling language for customization, incorporation of interdependencies between components, implementation of decision logic and updating information as a result of learning. We illustrate how such a system identifies which uncertainties impact the decision the most; values the acquisition of information (data, technical analysis) and encourages flexibility in go-forward plans to mitigate and/or exploit uncertainties. Further applications are to the optimization of development plans, real options valuation and the generation of consistent, risked cash flows for input to portfolio analysis. We believe that application of such a system results in a true value-driven focus to the work of multi-disciplinary asset teams through its ability to integrate the technical and business aspects of decisions.