bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chestnut – A Successful, Innovative Development of a Small, Marginal North Sea Oil Field
Authors: Wood P. , Coghlan G. 
Published: February 2011

Abstract
The Chestnut field, discovered in 1986, is located in license block 22/2a in the UK Central North Sea. The reservoir is a high quality, deepwater sandstone in the Eocene-age Nauchlan Formation. Appraisal drilling confirmed a complex sand distribution and constrained volumes of ca.30° API oil. The sands are relatively thin, though of high quality (several Darcies), of limited predictability and occur in a flat structure with a short oil column.
In 2001 a keeper, horizontal appraisal well was drilled and an extended well test performed to investigate OIIP and the dynamic reservoir/well behaviour. Performance was towards the low end of expectations and consequently the commercial challenges led to the withdrawal of most of the original participants in the joint-venture.
Venture Production (now Centrica Energy) began building its interest during 2001 taking a majority stake and operatorship in 2003. A novel development strategy was required to manage the many commercial risks of such a marginal project. Capex and opex exposure were mitigated by identifying the potential of a cylindrical FPSO design solution, then working closely with its developer, Sevan, the relevant authorities and field partners to achieve the right design for a North Sea deployment.
A Field Development Plan was approved in late 2005 using the Sevan FPSO design with tanker shuttle export. The initial development used the 2001 appraisal well and one water injector drilled in 2006. Initial reservoir pressure was only slightly above saturation pressure and pressure maintenance is required to minimise gas evolution in the reservoir. First oil was produced in September 2008 and injection started in December 2008. An additional producer was drilled, completed and put on production in Mar. 2009
This paper will outline the approaches that evolved to manage multiple, irresolvable, subsurface uncertainties so that a field investment decision could still be made against a background of capital constraints.
A Pragmatic Approach to Frac-Pack Tool Erosion Qualification Testing
Authors: Clem Nicholas J. , Hammer Aaron C. , O'Connell Maria M. , Amaral Anderson da 
Published: February 2011

Abstract
Frac packing tool erosion is a growing concern as more high-profile deepwater wells are completed using this technique. Today many deepwater wells require frac pack pump rates of at least 40 barrels per minute (bbl/min) with proppant loads reaching 300,000 lbm. As zone lengths are increased and multizone operations are performed, jobs requiring 60 bbl/min pump rates with proppant loads reaching 1,500,000 lbm are becoming more typical. The current frac packing tool designs must be optimized to accommodate the higher pump rates and proppant volumes required to complete these deepwater wells.
Extensive research and development, including computational fluid dynamics analysis and scale-model erosion testing, have led to the development of a new series of sand control tools that have been optimized for ultra-high-rate frac packing applications. Analyzing various patterns such as velocity, fluid path, erosion, and sand concentration at high rates helps identify critical areas within the system that require design optimization.
Results from full-scale erosion qualification testing of this new series of sand control tools are discussed. The qualification tests are designed to simulate extreme applications for tools in terms of pump rate, treatment volumes, and proppant properties, while testing conditions remain consistent with actual job specifications. The qualification test parameters were chosen to emulate and, in some cases, exceed the parameters of frac pack treatments currently being planned for the deepwater Gulf of Mexico. Erosion properties of the crossover, extension, and casing will be discussed, and depicted.
Friction Pressure Performance of Commonly Used Viscous Gravel-Packing Fluids
Authors: Jain Samyak , Gadiyar Bala , Stamm Bryan , Abad Carlos , Parlar Mehmet , Shah Subhash 
Published: February 2011

Abstract
Gravel packing is increasingly used in long horizontal wells and challenging environments. Key to successfully executing the gravel-pack job is selecting an appropriate gravel carrier fluid. Friction pressure loss exhibited by gravel packing fluids is an important consideration in their selection. This paper discusses the friction pressure performance of commonly used gravel packing fluids in the industry today which include Visco Elastic Surfactant (VES) type fluids, Xanthan and Hydroxyethyl Cellulose (HEC).
In wells with long horizontal section or narrow margin between pore pressure and fracture gradients the friction pressure loss exhibited by these fluids in the washpipe and washpipe/basepipe annulus governs whether these wells can be gravel packed without fracturing the formation. In gravel packs with alternate path configuration (shunts) the friction pressure loss through the shunts controls the maximum length that can be gravel packed.
This paper discusses in detail the fluid friction pressure performance while pumping these fluids through various conduits including circular pipe, eccentric annuli and rectangular tubes (shunts). These data were generated in field-scale yard tests under controlled conditions, both for ambient and elevated temperatures. The paper also discusses the rheological properties of these fluids at ambient and elevated temperatures. The effect of factors such as surfactant/polymer concentration, addition of gravel, and temperature on the friction pressure loss of these fluids is presented which will help in fluid selection/optimisation under different scenarios.
Real-Time Long-Distance Teaching: The Texas A&M DL Experience
Authors: Teodoriu C. , Barrufet M. , Epps M. L. , Falcone G. , Reinicke K. M. 
Published: February 2011

Abstract
This paper presents the experience gained while using a commercial web based tele-teaching technique which includes live participation of the DL students. Unlike the recorded classes, the on-line interaction offers a better knowledge transfer and teaching process control.
We show the advantages of this new concept and the student response to the teaching process for a highly sophisticated petroleum engineering class delivered to students located world-wide from our offices in College Station, Texas (server location) and Clausthal-Zellerfeld, Germany (teacher location). The experience over two years of tele-teaching using this web package has resulted in enthusiastic student acceptance. This paper is a following up of our previous paper that was presented at the ATCE 2009 and enjoyed a tremendous interest of the audience, and gives answers to some of their questions.
Innovative Field Camp for Education and Industry-Academic Collaboration in Geology-Based Reservoir Model Building for Carbonate Reservoirs in the Middle East
Authors: Gupta Anuj , Poppelreiter Michael 
Published: February 2011

Abstract
Jebel Fuwairit, Qatar, is a unique geological site where an active and fossil coastal spit are developed next to each other. It offers opportunities to study active carbonate forming processes and map the fossil formations. Heterogeneities of carbonate depositional systems and early facies related digenesis are available for investigation on multiple scales: bed-body-reservoir. It provided a unique opportunity to establish a training section and digital model for education and training/collaboration site for professionals in industry.
Primary objective is to provide students experience in measurements/ research methods for developing a digital model of an oil/gas reservoir based on an outcrop study. Another objective is to establish a hands-on training opportunity for professionals/ students to learn the process of rock based reservoir model building.
Field camps were conducted to collect GPS mapping of key surfaces, cross-beds and several sedimentological sections in combination with rock samples, and facies/ microfacies descriptions. Photo panels of several cliff sections were created. CT-scan and porosity/permeability measurement of hand samples were conducted to understand the pore architecture for such carbonates. Work continues on integrating measurements at different length scales in a 3D digital model of the reservoir.
Jebel Fuwairit outcrop has never been described before. This work will create the first 3D digital geology model for Qatar and unique educational experience for students. This outcrop in Qatar, studied jointly with geologists and reservoir engineers from industry, is a beach-bar complex that is an analog for Upper Jurassic Arab and Lower Triassic Khuff Formations (K2/K1 sequence), which hold most of the oil/gas reserves in the Middle-East.
The Hydrocarbon Systems of the Vienna Basin and Their Characterization
Authors: Potsch K. , Zach C. 
Published: February 2011

Abstract
When exploring within the same basin one is tempted to assume that there is a main source rock from which the reservoir fluids originate. This work analyses the fluids of the discovered reservoirs in the Vienna Basin firstly by their traditional parameters like saturation pressure, stock tank liquid density, gas-liquid ratio etc. This leads to one set of categories of the reservoir fluids.
Another way is to analyse the "plus-fraction". Its shape gives an indication whether it is a mixture of different "source"liquids. Liquid chromatography is the basis for this approach. It allows for determining the amount of higher components (carbon numbers). Using that analysis on can build the properties of the pseudo-fractions that are essential for reservoir simulation. Usually only density and molecular mass are known of the C6+ fraction that mainly constitutes the stock tank liquid. For gas injection processes a more detailed fluid description is desired to carry out compositional simulations. This paper presents investigations of a variety of liquid hydrocarbon distributions. They show that it is not possible to fit one general type function by matching a few constants. Different types of functions are required for a proper fit, among which is the well known Gamma-function.
Having found the best fitting function, one can firstly find a very good estimate of the pseudocomponent properties. Secondly, the fitted function helps in case of contamination by oil based mud. Thirdly, it might even help to classify oils according to their origin if one has access to a wide data base.
Challenges in Designing, Planning and Execution of Well Completions for Highly Depleted Reservoirs, and High Differential Pressure Between Reservoirs
Authors: Imran T. N. , Al Izudin A , Natasha M. S , Samsudin N. , Rameli M. F. , Hamid A. A. , Elliott C. , Khalid M. Z. , Zeidan A. A. 
Published: February 2011

Abstract
As part of the second stage development of a mature oil field offshore Malaysia, deeper reservoirs in Field S were identified from four different blocks. In order for the wells to be economically viable, up to eleven (11) sands were planned to be completed. This proved to be challenging due to the high differential pressures between reservoirs, highly depleted zones above the target sands, and pressure and reserve uncertainties of the target sands.
This paper covers design, planning, and execution of the well completion for four (4) infill wells where the differential pressure between zones was predicted to be up to 1,700 psi (Pounds per Square Inch). Some of the zones were highly depleted, and the most depleted zone was 0.216 psi/ft (Pounds per Square Inch per Foot). Even with the lowest brine weight of 8.5 ppg (Pounds per Gallon), the over balance was about 1,800 psi.
The completion was designed to maximize the number of sands in each well (eleven (11) sands with six (6) zones) to gain maximum production, while at the same time the short string needs selectivity. One of the challenges was the production casing design could not be larger than 7". To facilitate selectivity on the short string, the upper completion was designed with a Y-block.
To avoid significant losses from high overbalance and differential pressures, stage-by-stage perforation was planned. However, the challenge was to achieve the required under balance across all the zones since there was no stimulation planned. Both static and dynamic under balance perforation techniques were used for perforation.
With all the upfront planning and design, the well completion operation was successfully executed with less than 1% Non Productive Time (NPT) recorded, which was an excellent achievement considering the complexity of the completion design and operation.
In conclusion, the post-analysis showed the production rate target was successfully attained - indicating the formation damage was minimal even though the wells were drilled and completed with more than 1,000 psi overbalance.
New Perspective on Gas-Well Liquid Loading and Unloading
Authors: Veeken C. A. , Belfroid S. P. 
Published: February 2011

Abstract
This paper discusses the multiphase flow mechanism responsible for gas-well liquid loading. It shows that the conventional idea of droplet flow reversal (Turner et al. (1969)) does not capture reality and that actual observations are better described by film flow reversal. This paper subsequently explores how film flow reversal changed views on existing gas-well liquid unloading techniques such as continuous foam injection, and discusses new manners of gas well deliquification that specifically aim to delay film flow reversal. The benefits of different types of tubing wall modification have been evaluated via small-scale lab testing. Most promising, hydrophobic coating of tubing reduces the gas rate below which liquid loading occurs by about 50%. The benefits of hydrophobic coating are translated to representative field conditions.
Downhole Vibration Measurement, Monitoring, and Modeling Reveal Stick/Slip as a Primary Cause of PDC-Bit Damage in Today
Authors: Ledgerwood L. W. , Hoffmann Olivier J. , Jain Jayesh R. , El Hakam Carmel , Herbig Christian , Spencer Reed W. 
Published: February 2011

Abstract
Since backward whirl was discovered as a severe cause of PDC bit failure, our industry has made great strides toward creating whirl-resistant bits and operating practices. But is whirl still the major cause of PDC bit damage in today's applications? This paper reports on a recent field study in which downhole vibrations were measured using a newly available in-bit vibration-monitoring device. The focus of this study was to understand today's North American vertical conventional rotary applications. In addition, four wells were also drilled using a research drill rig in Oklahoma. In these tests, PDC bits, BHAs, and operating parameters were varied to document their effect on downhole vibrations. In these four wells, vibration measurements from the new in-bit measuring device were validated against a commercially available and industry-proven MWD vibration monitoring service. Also, a computer model that accounts for the coupled response of bits and BHAs was run for selected tests in field wells and the research drilling rig. The models agreed well with the measured cases in both whirl and stick-slip. The model also allowed the authors to confirm that high-frequency torsional oscillations (4-9 Hz) which we observed were, as a previous industry paper suggests, due to BHA torsional resonance.
The results of this study indicate that the most common field vibration today in hard rock PDC drilling is stick-slip, not whirl, in the target test region. In field tests, stick-slip was almost exclusively observed. For typical field applications with a surface rotary speed of about 70, we have measured peak downhole RPM during the slip phase as high as 500. This paper will report on these findings, document damage resulting from stick-slip, and suggest potential solutions to mitigate downhole vibrations.
A New Technique for Accurately Measuring Two-phase Relative Permeability Under Non-Darcy Flow Conditions
Authors: Lai Bitao , Miskimins Jennifer L. 
Published: February 2011

Abstract
A new steady-state technique for determining gas-water relative permeability curves for proppant packs under high confining stress conditions is presented. In this technique, a time domain reflectometry (TDR) device that can measure the saturation inside the proppant pack instantly and efficiently is introduced. De-aired water and nitrogen gas are simultaneously injected into the proppant pack under a desired confining stress, and the pressure drop and saturation are measured when steady-state conditions are reached. Two different proppant mesh sizes, 12/18 and 20/40, have been tested under four confining stresses ranging from 10004000 psi with repeatable and accurate results.
In the majority of published techniques, two-phase relative permeability curves are determined by using Darcy's law. This might be accurate enough for low permeability formations under low flow rate conditions, but in high permeability fracture proppant packs, the non-Darcy flow effects, or inertial effects, cannot be neglected. Thus relative permeability curves neglecting inertial effects may lead to inaccurate predictions. In this paper, three flow models: the classic generalized Darcy ‘s Law, the generalized Forchheimer flow model, and the two-phase Barree and Conway model (Barree and Conway, 2007) are employed to calculated and compare the relative permeability results. The experimental results show that the non-Darcy flow effects on gas relative permeability are higher than those calculated using Darcy's Law. In addition, the various confining stress effects on water and gas relative permeability curves are also presented. A significant decrease in gas relative permeability and minor effects on water relative permeability occur as the confining stress increases. These results help to further understand the effects of multiphase flow in porous media.
Amplifier/Booster Joint Positioning Framework Design for a High-Speed Wired Telemetry System in MWD/LWD Downhole Tool Environment
Authors: Rath Sumit , Mandadi Sharath , Thamizhmani Vivek , Samuel Robello 
Published: February 2011

Abstract
Data transmission from downhole tools to the surface is extremely important to drilling engineers for real-time decision making and well economics. With new advances and innovations in downhole technologies, particularly in the areas of drilling optimization and MWD/LWD technologies, the current data transmission rates are insufficient for the complete use of all downhole data that can be acquired. Digitization of transmission systems can increase the overall efficiency and accuracy of data acquisition systems. The benefits include increased reliability and large volumes of data on which to base current and future decisions. With its innovative technology, a high-speed wired telemetry drill pipe system can achieve this. The network, consisting of embedded wires along the drill string, can achieve higher transmission rates from downhole tools to the surface in real time; it enables the complete use of technological advances in approximately the same amount of rig time as is required with mud pulse or electromagnetic telemetry systems. This paper presents a study of the wired telemetry system and describes the importance of placing an amplifier/booster system to efficiently enable the data signal transmission from downhole to the surface systems. An accurately placed amplifier/booster system is an essential part for the success of the wired telemetry system. It will address signal losses and can ensure that the integrity of essential signal parameters (such as bandwidth, bit accuracy, signal strength) remains consistent throughout the transmission path. This paper presents case studies of the factors responsible for the losses in the telemetry system and the design an optimized amplifier/booster placement system to overcome those losses to achieve the objective of efficient transmission of acquired data from downhole tools.
Vibration Analysis and Control with Hole-Enlarging Tools
Authors: Samuel Robello , Yao Dongping 
Published: February 2011

Abstract
In high-risk, high-cost environments, such as ultra-deep waters, refining advanced technologies for the successful completion of wells is paramount. Challenges are still very much associated with complex bottomhole assemblies (BHAs) and with the vibration of the drillstring when used with hole enlarging tools. These tools with complex profiles and designs become additional excitation sources of vibration. The more widespread use of downhole tools for both directional telemetry and logging-while-drilling (LWD) applications, as part of the front line data acquisition system within the drilling process, has made reliability a prime area of importance. This paper presents and validates an existing model to predict severe damaging vibrations. It also provides analysis techniques and guidelines to successfully avoid the vibration damage to downhole tools and to their associated downhole assemblies when using hole enlarging tools, such as hole openers and underreamers. The dynamic analysis model is based on forced frequency response (FFR) to solve for resonant frequencies. In addition, a mathematical formulation includes viscous, axial, torsional, and structural damping mechanisms. With careful consideration of input parameters and the judicious analysis of results, we demonstrated that drillstring vibration can be avoided by determining the three-dimensional vibrational response at selected excitations that are likely to cause them. In addition, the analysis provides an estimate of relative bending stresses, shear forces, and lateral displacements for the assembly used. Based on the study, severe vibrations causing potentially damaging operating conditions that had been a major problem in nearby wells were avoided. Simple guidelines are provided to estimate the operating range of the drilling parameter to mitigate and avoid the downhole tool failures. Extensive simulations were performed to compare the data from the downhole vibration sensors; this paper includes severe vibration incidence data from three case studies in which the model estimated, predicted, and avoided severe vibration.