bluuebunny/crossref_metadata_2025 huggingface dataset:
Appropriation and rationality in hip hop groups organization practices in Porto Alegre: an analysis on the perspective of Guerreiro Ramos
Authors: Camara Guilherme Dornelas , Goulart Sueli , Reinher Rafaela Mendes
Published: October 2012

This paper discusses the organizational practices of hip hop groups from Porto Alegre, southern Brazil, as they appropriate foreign experience and rationally guide their social action. The aim of this work is to investigate these practices, based on the formulations of Brazilian sociologist Alberto Guerreiro Ramos, as they are enunciated in the works The Sociological Reduction and The New Science of Organizations. This approach offers fruitful material to broaden the theory and may be subsidiary to this kind of socio-cultural study, explaining why it is pertinent in this field. In this sense, the hip hop movement can be viewed as valuable when it comes to understanding phenomena which, due to (and in spite of) being originally transnational, or even "foreign", act or interact worldwide. Examining the organization practices and social action of these groups also helped identify a concern with the production of cultural artifacts that represent and form a symbolism that is historically and culturally located. Another issue that was broached concerns the market since for those groups it is not a category absent from their struggles and actions, but the economic criteria are incidental in relation to their members' motivation.
Treatment of Obstructive Sleep Apnea in Infants with Trisomy 21 Using Oral Appliances
Authors: Linz Annette , Urschitz Michael S. , Bacher Margit , Brockmann Pablo E. , Buchenau Wolfgang , Poets Christian F.
Published: October 2012

Objective

To perform a retrospective study to evaluate the effect of oral appliances, aimed at increasing the pharyngeal space, on obstructive sleep apnea (OSA) in infants with trisomy 21 (TS21).

Design and Setting

Retrospective study in a tertiary referral center.

Intervention

We analyzed data from 51 consecutive infants (mean age, 2.7 months) who underwent polysomnography (PSG) and were offered our treatment concept. Primary study variable was the mixed-obstructive apnea index (MOAI); OSA was defined as a MOAI ≥ 1.

Results

Twenty-seven infants (53%) had OSA. Their median MOAI improved from 2.3 (1 to 13) to 0 (0 to 0.2; P < .05). Seven of these infants were treated with an appliance that included some type of velar extension to move the tongue base forward. Of the 24 infants without OSA at admission, follow-up PSG results were available for 13. Three infants from this group had developed OSA by the time of a repeat PSG.

Conclusion

In patients with TS21, OSA may already develop in infancy. Early treatment may improve OSA. Oral appliances with some type of velar extension may be considered as an alternative to other treatment procedures.
Coupled modelling of flood due to natural landslide dam breach
Authors: Huang Wei , Cao Zhixian , Yue Zhiyuan , Pender Gareth , Zhou Jifu
Published: October 2012

A coupled two-dimensional mathematical model is presented for a flood due to natural landslide dam breach. A new numerical algorithm is developed, preserving the well-balanced property between the flux and source terms of the momentum conservation equations over a mobile bed. It allows for the wetting–drying transition to be properly resolved. Equally importantly, the spatially variable size of the sediments of natural landslide dams is taken into account in estimating bed sediment entrainment flux. The model is first tested against flume experiments and then applied to a case study of the Tangjiashan landslide dam, the largest of its kind generated by the 2008 Wenchuan earthquake in Sichuan Province, China. Compared with field observations, the widening and deepening of the breach along with the flood hydrographs are reproduced fairly well by the present model as the heterogeneity of the dam material is incorporated. In contrast, when the heterogeneous composition of the natural landslide dam is ignored using a fixed sediment size, the model fails even if the parameters related to roughness, entrainment flux and mass collapse are largely tuned. An appropriate account of the heterogeneous composition of natural dams is therefore significant.
Design flood flows with climate change: method and limitations
Authors: Darch Geoffrey John Caedmon , Jones Philip Douglas
Published: October 2012

An extended method is presented for ‘perturbing' design flood flows to account for climate change. Specifically, the method uses climate model output to directly alter parameters in the UK Flood Estimation Handbook rainfall–runoff model. The method is explored using a model of the River Eden catchment in northwest England, which comprises 26 sub-catchment hydrological models, with outflows routed using a hydraulic model. The results show a significant increase in flood flows and water levels by the 2080s, although uncertainties are large. The size of the increases varies depending on the climate change scenario and timing of the event, with the monthly precipitation change factor the single largest determinant of the change in peak flow. The method is reasonably simple to apply and there are benefits of using climate model information, rather than a sensitivity allowance, in terms of geographical interpretation of changes in precipitation and explicit representation of some of the uncertainty related to climate change. However, there are significant limitations to the methodology, in particular the minimal representation of antecedent conditions and more generally due to the ability of climate models to accurately reproduce and simulate extreme precipitation.
Integrated modelling for urban surface water exceedance flows
Authors: Ellis J. Bryan , Viavattene Christophe , Chlebek Jennifer , Hetherington David
Published: October 2012

The basis for an integrated modelling approach to pluvial exceedance flooding is described together with the principal challenges and uncertainties associated with the extraction and interpretation of the terrestrial Lidar (light detection and ranging) data survey used to derive high-resolution digital elevation modelling (DEM) of the urban surface micro-topography and morphology. The terrestrial Lidar DEM has been developed within an integrated sewer/overland flow modelling approach using a coupled geographic information system (GIS)-based one-/two-dimensional framework. The advantages of mobile ground-based Lidar over airborne survey systems are examined in terms of the definition of appropriate grid cell sizes and scaling for the accurate quantification of flood distribution, depths and flowpaths as required for the identification of ‘critical drainage areas'. The performance outcomes of an innovative sustainable urban drainage (Suds) selection tool (Sudsloc) are also examined in terms of varying DEM conditions and the accuracy of the predicted flood depths and distributions. The integrated modelling application provides a flexible and robust risk assessment tool for predicting and managing pluvial flooding in urban catchments.
Unconventional Cementing Method Enables Drilling in Lost-Circulation Zones: Case History
Authors: Hernández Rafael
Published: October 2012

When drilling in lost-circulation-prone locations using conventional cements and circulation methods, significant challenges can be encountered during primary cementing operations. Using conventional circulation cementing methods might not be the best choice in circumstances where a w llbore has formations with low fracture gradients unable to withstand the pressure commonly associated with conventional circulation cementing operations. The formation could possibly breakdown under the pressure applied by the cement, causing the cement to be lost into the formation.

Cement lost into the fo mation is undesirable because of the associated damage and expense. To overcome these challenges, the use of an unconventional cementing method during primary cementing operations is proposed. This method reduces the equivalent circulation densities (ECDs), minimizes excess cement volumes, and eliminates displacement, thereby increasing the chances of a s ccessful cement job with minimum environmental impact. Reverse circulation can significantly reduce bottomhole pressures and allow placement of cement with no apparent losses in many cases. This unconventional cementing method is discussed and a case history is presented.
Increased Tubular Running Efficiency on Drilling Rigs
Authors: Cummins Tracy , Sinnott Aaron , Forestier Danny
Published: October 2012

The drilling industry continually seeks enhanced technologies and processes that reduce time spent drilling and completing a well while maintaining well bore integrity, particularly with the installation of casing and tubing and the handling of tubulars in general. Over the years, major focus has been placed on the handling of tubulars and efforts to handle most preparatory functions offline rather than on the rig itself, thus generating greater efficiency and improving health, safety and environmental (HSE) conditions.

Many newly constructed rigs are equipped with auxiliary pipe makeup stations and racking systems for offline makeup and racking and installation of casing and tubing in stands. As a result, run times have improved at well centers by as much as 100% while reducing risk exposure to personnel. But the vast majority of existing rigs is not equipped to handle pre-made stands of casing and tubing and therefore is unable to take full advantage of these potential efficiency gains. One option for enhancing rigs without offline makeup and racking capability is to prepare and pre-assemble the casing or tubing into stands at a pipe handling yard and subsequently ship them to the rig to be picked up and run as stands at well centers on the critical path.

In this paper the authors will review the use of tubular management facilities for offline preparation of tubing and casing. We also assess the savings potential associated with moving makeup and breakdown operations from the drilling rig critical path. We will document recent projects in Australia, Asia and the Gulf of Mexico in which the tubular running service company improved efficiency by managing logistics, preparation and preassembly of tubular stands, safe installation and shipment to the operational rig.
An Integrated Horizonal and Vertical Flow Simulation with Application to Wax Precipitation
Authors: Trina S. , Johansen T.
Published: October 2012

There is a lack of comprehensive simulation tools that (a) accommodates the complexities of advanced completions together with near wellbore behaviour, and (b) has reliable wax precipitation models for production planning. In this work, these issues are tackled by combining three specific models. Firstly, a steady-state, three-phase, non-isothermal flow model in advanced horizontal completions was implemented to run fluid specific simulations, thereby calculating field specific flow conditions. This is useful in situations when fluid specific temperature calculations are important, such as wax crystallization. Secondly, a non-isothermal vertical flow model was developed by combining Hagedorn and Brown's multi-phase flow correlation with Ramey's multi-phase temperature model by solving them in sequence (iteratively). The advanced horizontal well model and vertical flow model were coupled iteratively at the bottom hole where the two models meet. Thirdly, two different analytical wax crystallization models were incorporated in the above coupled flow simulator to calculate the location of wax precipitation along the vertical section of the well. These three simulation models, individually and in combination, were tested and found to be in par with theory, expectations and published results. Additionally, significant difference was noted between Ramey's analytical temperature profile (which is a widely used approximation) and the complete Ramey's model integrated with the simulator developed in this work.
From High Perm Oil To Tight Gas - A Practical Approach To Model Hydraulically Fractured Well Performance In Coarse Grid Reservoir Simulators
Authors: Burgoyne M. W. , Little A. J.
Published: October 2012

The Dynamic modeling of induced hydraulic fractures in finite-difference reservoir simulation has historically been a complex, time-consuming and error-prone process that is unsuited to practical application and difficult to reconcile with corresponding analytical solutions.

The methodology and workflows presented in this paper address the above problems and provide a process whereby the pressure-rate response of hydraulically fractured wells may be practically and reasonably accurately modeled in coarse-grid reservoir simulation models without recourse to the high computing-overhead methods commonly employed.

The correlations and methodologies presented here have been developed by describing fracture behaviour as a function of fracture half length, grid block size and dimensionless fracture conductivity, and ‘history-matching’ simulated well performance against accepted analytical and simulated responses for a wide range of reservoir and fracture properties. The methodology is applicable to multiple well scenarios (e.g. vertical, partial block fracture penetrations, block aspect ratios not equal to unity, horizontal wells as well as multi-stage hydraulic fractures in single grid blocks), does not require fracture completion information prior to grid construction, and can be implemented in the recurrent section of a simulation project.
Surface Profile Evolution Due to Long Term Exposure to Solid Particle Erosion
Authors: Wong Chong Y , Solnordal Christopher , Wu Jie
Published: October 2012

Traditional erosion modelling on oil and gas equipment frequently assumes a fixed erosion rate and unchanging surface profile throughout the erosion exposure period. This approach does not account for the constantly changing surface and changes in the fluid flow, and may therefore lead to large uncertainties in the prediction of equipment life. The literature presents limited experimental data of generic configurations in this topic. The paper addresses this gap by experimentally and numerically investigating three generic configurations often encountered in oil and gas facilities. These configurations are: a cylindrical rod, a hole in a flat plate and a pipe cavity.

Particle erosion prediction is not a mature science as it requires predicting the dynamic paths of particles impacting on the target surface and linking this to the removal of parent material at the equipment surface. The authors have employed a modelling approach utilising qualitative and quantitative laboratory testings in parallel with Computational Fluid Dynamics (CFD) to determine the long term erosion profiles of the abovementioned configurations in a flow field suspended with dilute solid particles. Taken together, this approach provides an alternative quantitative method in assessing equipment longevity/failure due to solid particle erosion relative to empirical/analytical erosion modelling.
Fresh Water Conundrum in Oil and Gas Reservoirs of Malaysia
Authors: Kyi Ko Ko , Hashim Hazlina
Published: October 2012

Positive identification of a water bearing interval is crucial to evaluating hydrocarbon bearing reservoirs in a well. Accurate estimation of formation water resistivity is also critical for proper computation of reservoir parameters used in hydrocarbon resource assessment. In reservoirs with high formation water salinity, it is relatively easy to differentiate water bearing zones from those bearing hydrocarbon. However, when the salinity of formation water is low, close to being fresh water, it becomes difficult to positively identify a water bearing reservoir, since the formation resistivity is relatively high. In some cases, a fresh water bearing interval may be misinterpreted as a hydrocarbon zone. In the Malay basin, offshore Malaysia, there are several reservoirs which contain relatively fresh formation water, making it difficult to evaluate the well logs from these reservoirs. Furthermore, some of these reservoirs are deep and have low porosity, which in combination with low formation water salinity, lead to relatively high formation resistivity. In certain reservoirs, there may even be some hydrocarbon shows, such as an oil stain on cuttings, which may have been due to residual hydrocarbon effects. These often cause confusion and contention in interpreting the fluid type in these reservoirs. Several case histories are presented in this paper, highlighting the importance of proper identification of fresh water bearing formation in evaluating well log data. In one of the case histories, a fresh water bearing interval was misinterpreted as a hydrocarbon zone and tested accordingly, resulting in substantial flow of formation water with extremely low salinity. In the others, the formations tested had low porosity and permeability, resulting in very small influx of formation water into the well bore with practically no flow at the surface. Since some of these zones had hydrocarbon shows and the formation water did not flow to the surface during the tests, there was much contention about the validity of the well tests and the conclusion on the fluid type. The authors have proposed a "what-if scenario" method, whereby a synthetic water saturation curve is computed using generic capillary pressure data, assuming that these zones are hydrocarbon bearing. The resulting water saturation curves are then compared with those computed using the resistivity logs from these zones. The possible presence of hydrocarbon may then be inferred from the difference between these water saturation curves.
The Large Temperature Difference, Long Column and Narrow Clearance Cementing Best Practices in Halfaya Oilfield
Authors: Nie Zhen , Liu He , Liu Aiping , Sun Fuquan
Published: October 2012

Hundreds of horizontal and deviated cluster wells will be drilled in Halfaya oil field. Placing a nearly 3900 meter long and slim column of cement slurry along 7" production casing/liner in 8 1/2" hole proves to be a great challenge operation done on these wells. The long cement isolation interval translates into large temperature differences between the bottom hole and the top of cement with high circulating pressure during cementing job. In this case, the temperature difference can reach to 60∼70°C and Max. Inclination range is nearly 90 degree. On the other hand, the complicated geological conditions such as: abnormally high pressure (Max. PFP: 2.15g/cm3) with gypsum/salt zones, potential fractured losses and the presence of H2S, CO2 and high salinity aquifer etc. have also brought great difficulties for cementing. So, all these factors results in poor cementing quality in existing wells. This paper focuses on how we developed a new and high performance cement formulation and supporting technologies to effectively solve the cementing difficulties in this oilfield. The new developed cement slurry with density range from 1.30g/cm3 to 1.90g/cm3 has gotten high performance like leak resistance, good rheology ability and especially has good early strength development at the top of cement column. This technology can ensure the cement sets uniformly along the long column and ensure proper zonal isolation. Up to now, 12 wells cementing job have been conducted successfully, 95% of the CBL/VDL well logs show excellent cementing bonding quality. This paper discuss the details of a properly designed cement system and cementing operation and show field implementation result as kind of reference to the future similar cementing cases.
Comparison of DFIT, DST and IFT Permeabilities in CBM Reservoirs
Authors: Taco Gelber , Kamenar Alberto , Edgoose Jeff
Published: October 2012

The Diagnostic Fracture Injection Test (DFIT) is a welltesting technique used to assess the fracture growth, fracture closure and permeability from reservoirs; recently, it has been applied successfully to unconventional reservoirs such as: coal seams, tight sands and shale gas.

The conventional DFIT procedure shares similarities with the author's Step Rate Test (SRT) procedure; the author adapted the SRT for coal seams application in Australia more than 15 years ago, since then it has generated a data base of more than 700 tests. During this period, the SRT was primarily used to assess stress conditions in coal seam reservoirs.

Because of the similarities between the DFIT and STR procedures, we decided to apply the DFIT analysis technique to the SRT data with the aim to assess the coal seam permeability; furthermore, compare these permeability results with Drill Stem Test (DST) and Injection Falloff (IFT) permeabilities of tests undertaken in the same coal seam.

The permeability results from the three methods are not always similar and sometimes differ appreciably; this generates a dilemma for reservoir engineers because they need to choose a representative permeability for their production forecast and reserves recovery assessments. The explanation of these permeability differences relies on the interpretation of coal stress parameters provided by the DFIT analysis.

Furthermore, the appropriate integration of the DFIT, DST and IFT analysis results with wellbore storage, wellbore calliper and leak-off type, will assist the engineers to choose the representative reservoir permeability for their production forecast and reserves estimation; for this reason, running these three tests at the early stages of the exploration project will assists substantially with the property valuations and the planning of future work.
Non-Destructive Strength Index Testing Applications for Sand Failure Evaluation
Authors: Daniels Gillian , McPhee Colin , McCurdy Philip , Sorrentino Yelitza
Published: October 2012

Definitive rock strength data for sand failure evaluation are only available from tests on core plugs, however coverage is limited and core condition and geometry may preclude plugging. This paper presents results from a non-destructive core strength index tester that is less destructive than the Schmidt Hammer and less intrusive, easier, faster and cheaper than the core scratch tester. The portable index hardness tester measures and compares the impact and rebound velocities of a small steel ball after its collision with a rock surface to determine its hardness which in turn reflects the relative strength of the rock. The tester is run at regular intervals along the surface of the core to provide additional data that complement and enhance core rock mechanics data.

Several field examples are presented which illustrate the use of the index tester to optimise core sample selection, evaluate controls on rock strength, and to calibrate and constrain the development of wireline log-based strength models. Importantly, cases are included to highlight exceptions where the tester can produce misleading and even contradictory results.

The integration of index test results with core plug data and log analysis enables development of more robust rock strength models. The methodologies and techniques developed in this work have in turn enabled more accurate sand failure estimates that represent key tools in the development of effective sand management strategies for the reservoir life cycle for a variety of fields throughout the world.
Fracturing Net Pressure Diagnoses Modeling for Volcanic Reservoir
Authors: He Liu , Yang Gao , Lichen Zheng , Honglan Zou
Published: October 2012

Fracture net pressure examination is a widely used method before hydraulic fracturing. It is very crucial for understanding the characteristics of the formation, the complexity of the fracture as well as improving the success ratio of fracture operation, optimizing the fracturing design, evaluating the operating and the fracturing completion. Due to the nature of volcanic reservoir fracture mechanism, filtration mechanism, percolation mechanism, as well as the complex status of fracture initiation and extension of Daqing reservoir, in order to realize the characteristics of reservoir and fractures, and, to ensure the successful field operation, it is very important to conduct the test fracturing and field examination before major fracturing. After practising fracture tests in nearly 100 wells and analyze the effects of different volcanic reservoir physical characteristics on the fracturing operation, we developed six categories of G function pressure analysis methods and four standardized methods for examining the volcanic fracture complexity level by evaluating the characteristic parameters. We also developed fracturing operation technique for volcanic reservoirs and corresponding theoretical explanation methods, and built the specifications to control the operation risk which is based on the fracture test data, realized the accurate control scheme selection and effective execution, as well as improved the controllability on the fracturing operation of volcanic reservoir. According to the data collected from the filed operations, the success ratio is increased from 36% to 90% after applying this method.
HT/HP Fracturing Process String Evaluation and Application in Deep Volcanic Gas Reservoir
Authors: He Liu , Yang Gao , Lichen Zheng , Honglan Zou
Published: October 2012

The function of the fracturing strings is to transfer mechanical energy to crack the formations, and conduct proppant to the formations. Because the deep volcanic reservoir has the properties of deep burial, tight and complex formation lithology, the fracturing operations in such reservoir may encounter the issues of high downhole temperature, high operation pressure and high operation friction. The conventional fracturing strings are not capable of overcoming these problems. The fracturing strings are facing the following challenges:

1. Deeply buried volcanic reservoirs, which are normally deeper than 3000 meters, have very high temperatures, which are higher than 150 degrees Celsius. How to improve the temperature adaptability of the fracturing rubber packer is technically challenging. 2. The formation lithology of volcanic reservoirs is tight and complex, the initiation and extension of the fractures are relatively difficult. The operation pressure is high, so that the fracturing strings and other downhole equipment have to be able to sustain this high pressure. 3. Due to the high discharge rate and large scale operation in the process of volcanic reservoir fracturing, the fracturing strings should have low streamwise friction, strong anti-proppant erosion ability. In order to meet these challenges, we conduct the research on the fracturing equipment and fracturing strings used in the volcanic reservoirs. By studying the theoretical mechanics, optimizing packer structure, improving the temperature and pressure bearing ability of rubber packers, we design special tools such as anchoring tools to improve the adaptability of the fracturing technique, and also generate the safety specifications and operating regulations for the fracturing tools stripping in and out in the deep gas reservoir wells. All these achievements make the large scale fracturing remodeling of the deep gas volcanic reservoir possible. After the field tests, the success ratio is 97.5%.
Successful Application of Well Inflow Tracers for Water Breakthrough Surveillance in the Pyrenees Development, Offshore Western Australia
Authors: Napalowski Ralf , Loro Richard , Anderson Calan , Andresen Christian , Dyrli Anne Dalager , Nyhavn Fridtjof
Published: October 2012

This paper describes the interventionless approach that was successfully executed during the Pyrenees early production phase to identify the timing and location of water breakthrough. Chemical inflow tracers were installed in key production wells within the lower completion along the horizontal production sections. Results from this work have supported the reservoir simulation history matching process and confirmed the performance of the inflow control devices (ICDs). These data in conjunction with the real time rate information from subsea multiphase meters has allowed proactive reservoir and production management that has contributed to the early identification of additional infill opportunities.
Mineralogy and Petrophysical Evaluation of Roseneath and Murteree Shale Formations, Cooper Basin, Australia Using QEMSCAN and CT-Scanning
Authors: Ahmad Maqsood , Haghighi Manouchehr
Published: October 2012

It is found that in the deepest part of Cooper Basin (Permian section in Nappamerri Trough) in South Australia, two shale formations, Roseneath and Murteree have potential to be shale gas reservoirs. However, a comprehensive petrophysical evaluation has not been carried out so far. The free porosity among minerals, pore throat geometry, surface area and structure of micro pores for adsorption and diffusion of gas in these formations have not been well understood.

Two core samples from two wells (Della 4 and Moomba 46) were selected to evaluate mineralogy, free porosity and other petrophysical characterization. Since routine core analysis is not capable of petrophysical characterization of these very tight rocks, the latest technology of image scanning and processing of QEMSCAN (Quantitative Evaluation of Minerals using Scanning Electron Microscopy) and Computerized Tomography (CT) scanning have been used. QEMSCAN is a novel technology to process images from electron microscope to measure size and distribution of different minerals in a rock sample. QEMSCAN when combined with CT scanning can significantly enhance shale rock characterization and reservoir quality assessment. In this study, the main goal is the evaluation of total free porosity, micro pores and natural network of micro-fracture systems in our ultra fine samples.

Based on QEMSCAN analysis, it is found that the sample of Murteree shale has the mineralogy of quartz 42.78%, siderite 6.75%, illite 28.96%, koalinite 14.09%, Total Organic Content (TOC) 1.91 wt%, and pyrite 0.04%, while rutile and other silicates minerals were identified as accessory minerals. Total free porosity is found to be 2 percent. The free porosity is largely associated with clay minerals which shows intergranular linear, isolated and elongated wedge shaped pores. SEM images from the same core sample also show that the pores are mainly present in clay rich zone. QEMSCAN maps have revealed the location of lamination, high and low porosity zones as well as high and low sorption areas. In CT scanning, the porosity found in QEMSCAN, was not identified; however, a network of micro-fracture system in Murteree shale sample is identified.
The influence of pore space geometry on the entrapment of carbon dioxide by capillary forces
Authors: Pentland C. H. , Iglauer S. , Gharbi O. , Okada K. , Suekane T.
Published: October 2012

We investigate the characteristic properties of porous media that influence the entrapment of carbon dioxide (CO2) by capillary forces. It is known that different geological formations can trap different quantities of CO2 but the relationship between formation properties and trapping is poorly understood at present. Advances in micro computed tomography (µCT) techniques now allow the porous media and trapped CO2 clusters therein to be visualised and characterised on the micro meter scale. The context of this work is the geological storage of CO2 where the entrapment of injected CO2 by capillary forces on the pore scale is proposed as a fast and safe method to store injected CO2.

We analyse a series of saturated and unsaturated porous media using µCT; four glass bead packs, a sand pack and a sandstone. In the saturated images the pore space contains brine and residual CO2 (Sr) at subsurface storage conditions. We quantify Sr and cluster size distributions and determine characteristic properties of the porous media through image analysis and the extraction of representative networks. We show that media with narrower pore throats, such as sandstones, trap more CO2 than media with wider pore throats. Numerical simulations performed on the extracted networks do not accurately predict the measured residual CO2 saturations. We discuss the important implications of these results for CO2 storage site selection, containment security assessments, and storage capacity appraisal.
Operational Experience with Subsea Multiphase Flow Meters in the Pyrenees Development, Offshore Western Australia
Authors: Jackson Mark , Napalowski Ralf , Paris Nicholas , Moksnes Paul Ove
Published: October 2012

The Pyrenees Development comprises three oil and gas fields: Ravensworth, Crosby and Stickle. The fields are located in production licenses WA-42-L and WA-43-L, offshore Western Australia, in the Exmouth Sub-basin and are operated by BHP Billiton (Fig. 1). Eighteen subsea wells, including 14 horizontal producers, 3 vertical water disposal wells and 1 gas injection well have been constructed to date and additional wells are planned for infill and to develop additional resources. First oil was achieved during February 2010 and production exceeded 50 million barrels in November 2011. Figure 1Pyrenees Development Location Map

The Pyrenees fields are low relief, with oil columns of approximately 40 metres within excellent quality reservoirs of the Barrow Group. The 19° API crude has moderate viscosity, low gas / oil ratio (GOR), and a strong emulsion forming tendency which makes oil/water separation and accurate well test metering difficult. Early in the project design phase it was identified that the complex subsea gathering system and the need to reduce measurement uncertainties would dictate special attention to production measurement.

Subsea multiphase flow meters (MPFMs) were specified to meet the challenges of production optimization and allocation while at the same time minimizing production deferral for separator testing. Each oil producer is monitored by a dedicated MPFM. With 14 meters, Pyrenees is among the largest subsea MPFM installations worldwide.

This paper describes the process of MPFM qualification and commissioning together with their performance over 2 years in the field. We show how close cooperation between the Operator and MPFM Vendor has enabled quality rate measurements of emulsified production despite large changes in producing gas/oil ratio and water cut.

While the primary justification for Pyrenees subsea MPFMs was production allocation and optimization, interpretation of transient water cut and GOR data proved valuable for production and reservoir engineering applications. Examples of proactive reservoir and production management including optimizing drawdown of Inflow Control Device (ICD) equipped wells, optimizing well lineup and gas lift to commingled wells are presented.
Drillpipe for Shale Plays - Requirements, Considerations and Lessons Learned
Authors: Jellison Michael , Brock Jim , Muradov Andrei , Morgan Dan , Rowell Jim
Published: October 2012

Shale drilling for both natural gas and hydrocarbon liquids has increased dramatically in North America over the last several years. Shale oil and gas deposits are known to exist all over the globe including Australia and the rest of the Asia Pacific. This paper discusses the requirements for drillpipe in shale drilling applications along with a review of some of the challenges and problems associated with the drillstring in these critical applications. Most wells are horizontal with long departures. Typical wells in the Balkan Shale are 17,000 ft MD, 11,000 ft TVD with a 6,000 ft horizontal reach. Drilling these wells puts huge demands on the drillpipe and rotary shoulder connections and pushes the drilling equipment and rig crews beyond the requirements of typical onshore well construction projects. Many, if not most, of the shale wells require advanced design, double shoulder connections (DSC) on the drillstring to provide the enhanced torsional strength and streamlined connection dimensions required to effectively drill these prospects. The paper presents connection design solutions along with considerations for safe and efficient running procedures. Although, the advanced DSCs are designed to be transparent to normal drilling operations, compared to standard API connections, some problems have been encountered. The paper addresses these running and handling issues and provides guidelines to mitigate these problems. Excessive tool joint and drillpipe body wear have also been encountered in several shale plays. This is discussed, along with recommendations to limit wear. Stick-slip has created drillstring problems on several wells. Stick-slip can cause damage to the drillpipe and, in the extreme, downhole connection back-offs have occurred. The paper looks at aspects of case histories to illustrate these issues and provides lessons learned to improve shale drilling operations in North America, the Asia Pacific and other regions of the world.
Floating Production Platform Selection for Developing Deepwater Gas Fields off North West Australia
Authors: Xia Jinzhu , D'Souza Richard
Published: October 2012

Producing and delivering North West Australia (NWA) deepwater gas reserves to LNG plants poses unique challenges. These include extreme metocean conditions, unique geotechnical conditions, long distances to infrastructure and high reliability/availability requirement of supply for LNG plants. A wet or dry tree local floating host platform will be required in most cases. Whereas semisubmersible, TLP, Spar and floating LNG (FLNG) platform designs all have the attributes to be a host facility, none has been installed in this region to date.

This paper will address important technical, commercial and regulatory factors that drive the selection of a suitable floating host platform to develop these deepwater gas fields off NWA. Linkages between key reservoir and fluid characteristics and surface facility requirements will be established. A focus will be on the unique influence of regional drivers and site characteristics including metocean and geotechnical conditions, water depths and remoteness of these fields.
Estimating Zonal Gas-in-Place in a Commingled Well Using Results from Production Logs
Authors: Last Nick
Published: October 2012

It is becoming increasingly common to commingle two or more separate gas reservoirs in a single wellbore, especially in stacked-sand environments such as those frequently found in the Asia-Pacific region. Providing certain conditions are met, the total gas initially in place (GIIP) of the commingled reservoirs can be estimated using conventional material balance techniques. However, allocation of total GIIP to individual reservoirs presents a significant challenge. This paper describes how production logging (PL) results can be used, in conjunction with suitable dynamic modeling techniques, to define GIIP on a zone-by-zone basis.

The Selective Inflow Performance (SIP) technique for estimating pressures and deliverability of individual zones using suitable PL data is well established. Combining SIP results with other well information (including initial reservoir pressures and total well production) allows allocation of production to individual zones and calculation of their associated GIIP. This is done using a commingled well model (CWM) that matches both the initial well conditions and those obtained from the SIP results at the time of the PL. The paper sets out the minimum features of such a CWM.

The ability to allocate production to an individual zone, and to estimate its associated GIIP, presents opportunities to make better reservoir management decisions than is possible when only total-well information is available. Such decisions, including the location and timing of infill or step-out drilling, or whether to target well intervention at particular zones, may have large financial repercussions.
Successful Application Of 4D Seismic In The Stybarrow Field, Western Australia
Authors: Hurren Chris , Broad Carrie , Duncan Guy , Hill Robin , Lumley David
Published: October 2012

The Stybarrow Field is a moderately sized biodegraded 22° API oil accumulation reservoired in Early Cretaceous sandstones of the Macedon Formation in the Exmouth Sub-Basin, offshore Western Australia. The reservoir is comprised of excellent quality, poorly consolidated turbidite sandstones up to 20m thick. The field lies in approximately 800m of water and has been developed with five near-horizontal producers and three water injection wells. The Stybarrow development came online at an initial rate of 80,000BOPD in November 2007.

Due to the lack of significant aquifer support, water injection was planned from start-up for pressure maintenance. Acquisition of a variety of data types have enabled key subsurface challenges to be addressed both before and during production. Structural and stratigraphic complexities influence connectivity and therefore must be fully evaluated in order to achieve optimal sweep. A feasibility study concluded that Stybarrow would be a good candidate for 4D seismic monitoring. Two monitor surveys were acquired and, along with other reservoir surveillance techniques, have been used to refine the geological model.

The first monitor survey at Stybarrow was recorded in November 2008. The results of this survey were in agreement with prior 4D modelling and supported the drilling of a successful development well in the north of the field. A second monitor survey was recorded in May 2011, three and a half years after first oil and at 70% of expected ultimate recovery. This survey is currently being analysed to determine if sweep patterns have changed.

The 4D surveys have proven to be an important tool for understanding subsurface architecture and dynamic fluid-flow behaviour. The results of both 4D seismic surveys have provided significant contributions to understanding the dynamic behaviour within the reservoir to facilitate optimal reservoir management.
Stimulation of Stable Micro-Emulsion at Oil-Water Interface Using Co-Surfactants as an Alternative Method for Enhanced Oil Recovery
Authors: Bahar M. , Liu K. , Rashid A.
Published: October 2012

In order to screen various chemical and microbial EOR methods for core-flooding experiments and potential field trials, a laboratory investigation of evaluating the effect of micro-emulsion on the reduction of interfacial tension (IFT) was recently carried out at CSIRO by using commercially available chemical and bio-surfactants. Environment friendly non-ionic, anionic surfactants and a biosurfactant (Bacillus subtilis) were used to create micro-emulsion in an oil-brine system. Stable micro-emulsion (ME) was achieved by proportionally mixing various alcohols with surfactants.

Twenty-four micro-emulsion samples with five different chemical combinations were prepared for screening. All samples were stirred to create a stable ME phase. The volume changes of the ME phase were monitored over two weeks and their density, viscosity, and IFT were measured. The size distribution of ME phases was also characterised using optical microscopy equipped with an UV light source.

The micro-emulsion created by co-surfactants were found to be quite effective in reducing the oil-brine IFT and oil viscosity, and achieved ultra low IFT under reservoir pressure and temperature. There appears to be a linear relationship between the size of micro-emulsion and IFT reduction. ME with small sizes results in more IFT reduction and achieve stable ME at high temperature and pressure. Compared with the IFT reduction from the surfactant or microbial metabolism, the reduction of IFT through stable ME can be several orders of magnitude larger and may thus achieve better enhanced oil recovery in suitable reservoir systems.
A Variable Shape Distribution (VSD) Model for Characterization of Pore Throat Radii, Drill Cuttings, Fracture Apertures and Petrophysical Properties in Tight, Shale and Conventional Reservoirs
Authors: Aguilera Roberto F. , Ramirez John Freddy , Ortega Camilo , Aguilera Roberto
Published: October 2012

Fractal and power law distributions have been found in the past to be useful for modeling some reservoir properties following the assumptions of constant shape and self-similarity. This study shows, however, that pore throat apertures, fracture apertures, petrophysical and drill cuttings properties of unconventional formations are better matched with a variable shape distribution model (as opposed to constant shape). This permits better reservoir characterization and forecasting of reservoir performance.

Pore throat apertures, fracture apertures, petrophysical properties and drill cutting sizes from tight and shale reservoirs are shown to follow trends that match the variable shape distribution model (VSD) with coefficients of determination (R2) that are generally larger than 0.99. The good fit of the actual data with the VSD allows more rigorous characterization of these properties for use in mathematical models. Data that could not be described previously by a single equation can now be matched uniquely by the VSD. Examples are presented using data from conventional, tight and shale formations found in Canada, the United States, China, Mexico and Australia.

In addition, the study shows that the size of cuttings drilled in vertical and horizontal wells can also be matched with the VSD. This allows the use of drill cuttings, an important direct source of information, for quantitative evaluation of reservoir and rock mechanics properties. The results can be used for improved design of stimulation jobs including multi stage hydraulic fracturing in horizontal wells. This is important as the amount of information collected in horizontal wells drilled through out tight formations, including cores and well logs, is limited in most cases.

It is concluded that the VSD is a valuable tool that has significant potential for applications in conventional, low and ultra-low permeability formations and for evaluating distribution of rock properties at the micro and nano-scale.
Experimental and Numerical Studies on the Microbial Restoration of Natural Gas Deposits in Depleted Oil Reservoirs Storing CO2
Authors: Mori R. , Sugai Y. , Sasaki K. , Fujiwara K. , Nakamura T.
Published: October 2012

We investigated the microbial conversion of CO2 into CH4 in depleted oil reservoirs by the interaction between indigenous oil-degrading hydrogen-producing bacteria and indigenous hydrogenotrophic methanogens that have been found in oil reservoirs universally. In this study, we investigated the influence of crude oil, yeast extract, bicarbonate and CO2 on the growth and gas production of those bacteria through the incubation experiments of isolated strains under reservoir conditions. The yeast extract was estimated to be the most influential factor on the growth and gas production of oil-degrading hydrogen-producing bacteria. Methanogen was unaffected by the crude oil, the yeast extract and bicarbonate, however, both CO2 and H2 are assumed to be the influential factors on it because they are the energy sources of methanogen.

In addition, we also investigated their growth kinetics that were needed to construct a numerical simulator of the microbial conversion of CO2 into CH4 in depleted oil reservoirs. The specific growth rate of oil-degrading hydrogen-producing bacteria was increased as the yeast extract concentration increased while that of the methanogen was constant regardless of the yeast extract concentration. These results indicate that the growth of methanogens is unaffected by the yeast extract that is injected into reservoirs to stimulate the growth of ODHPB. The growth yield of HYH-8 and HYH-10 was 5.5×1010 cells/g-(yeast extract) and 3.5×1011 cells/g-(yeast extract) respectively.