bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonality and nitrogen supply modify carbon partitioning in understory vegetation of a boreal coniferous forest
Authors: Hasselquist N. J. , Metcalfe D. B. , Marshall J. D. , Lucas R. W. , Högberg P. 
Published: October 2015

AbstractGiven the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ 13CO2 pulse‐labeling technique to examine the short‐term dynamics of C partitioning in understory vegetation in three boreal Pinus sylvestris forest stands exposed to different rates of N addition: a low and high N addition that receive annual additions of NH4NO3 of 20 and 100 kg N/ha, respectively, and an unfertilized control. Labeling was conducted at two distinct periods (early vs. late growing season), which provided a seasonal picture of how N addition affects C dynamics in understory vegetation. In contrast to what has been found in trees, there was no obvious trend in belowground C partitioning in ericaceous plants in response to N additions or seasonality. Increasing N addition led to a greater percentage of 13C being incorporated into ericaceous leaves with a high turnover, whereas high rates of N addition strongly reduced the incorporation of 13C into less degradable moss tissues. Addition of N also resulted in a greater percentage of the 13C label being respired back to the atmosphere and an overall reduction in total understory carbon use efficiency. Taken together, our results suggest a faster cycling of C in understory vegetation with increasing N additions; yet the magnitude of this general response was strongly dependent on the amount of N added and varied seasonally. These results provide some of the first in situ C and N partitioning estimates for plants growing under the complex web of resource limitations in the boreal understory.
The Birth of Miriam Hazel
Authors: Cooper Rachel Shapiro 
Published: October 2015

ABSTRACTMy birth story for Miriam Hazel starts well before her birth, with the birth of her sister, our first-born daughter Colbie Laia. When I gave birth to our first daughter 3 years prior, I was in a completely different place with my body and my mind. Birth was scary, recovery was rough, and my first year followed suit. During my pregnancy with Miriam Hazel, my obstetrician encouraged me to consider a natural birth. I talked to other women and although still frightened, I became more confident and had the birth I never knew I wanted. The birth of Miriam Hazel was incredible and the recovery was completely different. This is my story of Miriam Hazel’s birth.
Drilling-with-Casing Technology Pilot Testing Results
Authors: Aleksandrov K. A. , Kiselev E. V. , Ovchinnikov S. N. , Tan M. , Gelfgat M. Ya. , Kulikov S. S. , Shilkin P. S. , Priymachenko D. A. , Fedoseev D. A. , Gnibidin V. N. 
Published: October 2015

Abstract
Well construction at Urengoyskoye field is associated with definite hazards confined to the formation section formed by relict permafrost rock (PFR). Combined thermal, physical, chemical and erosion effects on the wellbore walls result in collapse of ice consolidated sand clay sediments and easy washout by drilling mud flow. This leads to intensive caving and, thus, associated rock breakout and sloughing.
In addition, there are increased risks of the following problems:▪During construction in case of PFR thawing: lost circulation during drilling and cementing, low cement top;▪During further operation in case of PFR thawing and refreezing: subsidence, thaw sink formation, casing collapse.
Long PFR sections drilling time and high circulation rates also contribute to development of such undesirable processes.
To study risk mitigation options during surface casing section drilling, Rospan International CJSC decided to perform pilot testing (PT) of drilling-with-casing technology with a non-retrievable assembly (PDC drill bit, float valve). Such choice was conditioned by relative assembly simplicity and section geology enabling casing running section drilling in a single trip. In contrast to conventional drilling, in this case casing experiences increased stresses as it is the component that transfers mechanical and hydraulic power to the drill bit. Based on the above, it was decided to use casing with improved connections (metal-to-metal seals).
To improve reliability of pilot testing results, the tests were performed on three wells of the same pad. Wells drilled within the same license area using conventional drilling methods were taken as the basis for comparison. All process parameters were monitored and recorded both while normal drilling and in case of any drilling hazards.
Pilot testing results demonstrated that as compared to conventional drilling, no additional reaming of drilling tool drag or overpull sections was required. The potential of surface casing section construction time reduction was defined for Rospan International CJSC locations by improvement of the drilling-with-casing technology, in particular selection of optimal drill bit designs, use of casing with metal-to-metal seals (or with torque rings) with lower makeup torques, modification of the wellhead connection diagram.
Besides, comparative analysis of two drilling methods once again proved the plastering effect that has a positive effect during lost circulation control, which can further enable forecasting during drilling-with-casing at this field.
In general, PT results enable recommending the drilling-with-casing method with a non-retrievable assembly as a promising method for industrial implementation at fields with top sections represented by permafrost rocks. The expected surface casing section drilling time can be reduced by 1.5 or 2.0 times.
The First Application of Premium Port Technology to Conduct Zonal Stimulation and the Ability to Control the Well Injectivity Profile on a Unique Offshore Field in the Arctic
Authors: Koloda A. V. , Morozov O. N. , Panarin A. T. , Mukhametshin I. R. , Bulygin I. A. , Shestov S. A. , Ksenofontova A. A. 
Published: October 2015

Abstract
The reservoir of Prirazlomnoye field is composed of carbonate rocks. Premium port completion technology—a valve with an inflow/injection control device—was piloted in the Arctic offshore environment, allowing selective stimulation of the bottomhole pay zone and high-rate injection via both the ports and an inflow control device (ICD). This technology mitigated the risks of premature water breakthrough in the production well and improved the waterflood performance. The project began with the analysis to justify the use of premium port technology with ICD in the horizontal well based on the reservoir simulation model. The use of a slotted screen was compared against the premium port with ICD scenario. Then the project entered the second phase that involved well operations. Following the drilling and petrophysical interpretation of well logging data, the completion system parameters were computed to identify the number of premium port valves, packer installation intervals, and the number and sizes of ICD nozzles for each zone. This was followed by selective treatment with hydrochloric acid at specific pressures and injection rates. The horizontal hole was divided into five sections, each having a premium port valve for injection with ICD and an acid injection premium port. The intervals were separated by inflatable annulus packers. Every successful opening/closure of the valve was clearly observed at the surface. After the acid stimulation job, the well was successfully tested and brought into injection. The joint efforts of the drillers, completion engineers, and reservoir simulation engineers resulted in the selection and installation of suitable premium port valves and ICDs, driving the well performance close to its design parameters.
The simulation of the proposed technology using a sector model has shown a 5% increase of cumulative oil production against a 10% decrease of cumulative water production. Implemented in the existing offshore Arctic field, premium port technology has enabled selective acid treatment in individual reservoir zones, making it possible to reduce the skin to–1.4 on the average. This experience may be of interest to engineers in charge of selection of downhole equipment for challenging environments both on the continental shelf of Russia and beyond.
This paper offers an entirely new approach to the completion of horizontal wells enabling selective stimulation and injection management without the use of intelligent well completion systems in the harsh environment of the Arctic shelf. This technology has made it possible to mitigate the risks of water breakthrough into the production well and to improve the performance of the waterflood system.
Best Practices—Direct Emulsion-Based Drilling Solution as a New Approach to Drilling in Mature Fields with Low Reservoir Pressure
Authors: Sokovnin S. A. , Tikhonov E. V. , Kharitonov A. B. , Vian John , Bakirov D. L. , Babushkin E. V. 
Published: October 2015

Abstract
Currently, most fields in Western Siberia are classified as mature with significant reductions in reservoir pressure. This fact greatly complicates the drilling of horizontal wells in these fields. The role of quality and the requirements for drilling fluids increase significantly under such circumstances. Standard drilling fluids often fall short in achieving the drilling objectives because of significant overburdening of formations.
To resolve this issue, the geological information provided by an operator drilling in Western Siberia was used as the basis for developing an oil-in-water direct emulsion fluid system that reduces the likelihood of formation damage and allows trouble-free drilling under abnormally low reservoir pressure (ALRP) conditions. Filtration studies were carried out, and the impact on the restoration of the core's natural permeability was evaluated before this fluid system was used in the field.
Active use of this drilling mud system began in Western Siberia in 2002, with the drilling of horizontal wells. In their development, all wells showed much higher completion quality: an easy transition of the well into production mode without additional measures (swabbing, stimulation, etc.) and obtained production rates above those planned. The use of this type of drilling mud under ALRP conditions was accompanied by a substantial reduction in the risk of differential sticking, which in turn reduced the likelihood of losing expensive downhole equipment used in logging while drilling (LWD), measurement while drilling (MWD), and annular pressure while drilling (APWD), etc. Additionally, by aiding the maintenance of a minimum overburdening of formations, this fluid allows the use of conventional drilling equipment that does not require the time and cost of rig reconstruction, as is required in the case of oil-based mud (OBM).
Based on the analysis of drilling efficiency and completion quality conducted after testing the use of the emulsion fluid to drill horizontal wells in reservoirs with ALRP, the research institute of the field operator has recommended this technology for regular use, especially for reservoirs with low porosity and permeability properties.
The use of oil-in-water direct emulsion fluid is not intended as a replacement for the conventional water-based solutions used for reservoir completion in the cases of normal reservoir pressure values and in partially depleted reservoirs. However, where the reservoir conditions are such that the use of conventional water-based mud (WBM) is inefficient, the use of oil-in-water emulsion-based mud can substantially enhance drilling efficiency and completion quality.
Electromagnetic Heating for Heavy Oil Production: Case Study of a Field Applicability
Authors: Rafiee M. , Behr A. , Lessner E. , Diehl D. , Trautmann B. , Koch A. 
Published: October 2015

Abstract
Electromagnetic (EM) heating is a new promising technology to enhance the recovery in heavy oil reservoirs significantly. The method is in general not limited to depth and is able to homogenously heat up large volumes of a reservoir.
In this work the potential of heavy oil production by EM heating method has been investigated through conceptual numerical modelling including sensitivity analysis, based on data of a real oil field.
The idea is to place an electrical inductor loop into the reservoir, which heats up the formation up to a distance of 100 m. The heat (energy) is induced in-situ by applying an alternating current at medium frequencies of 10 kHz to 200 kHz to the inductor, which creates an alternating magnetic field and consequently induces eddy currents in electrically conductive parts of the reservoir.
The study compares different possible scenarios of the EM heating process as stand-alone or hybrid technology. As example of the latter, the combination with SAGD (steam assisted gravity drainage) was evaluated.
One of the success criteria of the technology is the availability of electrical conductivity in the reservoirs sufficient to transfer the energy into the oil saturated formation. Several electrical and technology design parameters for sensitivity analysis were explored in the study. The method is appropriate for a wide range of heavy oil viscosity. Permeability contrasts in the formation do not limit the amount of EM energy which can be introduced. Consequently, using a hybrid EM-SAGD approach, this combined technology is more efficient in heterogeneous reservoirs in terms of sweep, recovery factor and risk of steam leakage compared to SAGD alone. Energy balance calculations indicate that EM heating is attractive as well from economical point of view.
The findings of this study can be used for advanced Enhanced Oil Recovery (EOR) screening of EM heating methods in heavy oil reservoirs. The technology is suitable to improve conventional thermal methods. In hybrid processes, major reductions of water usage and a reduction of environmental footprint are possible.
The field study is part of an R&D project between Wintershall and Siemens to bring EM heating to field application.
New Mud-Pulse Telemetry System Delivers Improved Drilling Dynamics and Formation Evaluation Data
Authors: Cooper Paul , Santos Lucas Samuel 
Published: October 2015

Abstract
As wells become more challenging, the need for real-time data continues to increase. Drilling dynamics data allow faster drilling, while formation evaluation data allow accurate well placement to maximize reservoir value. Increased information from downhole allows better risk mitigation for safer drilling. The increased need for real-time data places higher demands on telemetry systems.
A new mud-pulse telemetry system is introduced based on an evolution of a proven annular venting pulser technology. This paper describes some of the engineering work undertaken to improve power management, actuation of the valve, and valve durability, thereby increasing the endurance and data rate of the system. Some of the compression algorithms and techniques developed to maximize the effective data rate delivered by the system are also described with examples of these techniques applied to real formation evaluation data.
This system has been deployed in multiple locations globally and has been run in the field more than 100 times. The paper presents information on the data rate achieved during these runs, demonstrating the step-change increase in performance over the current annular venting pulser system. Multiple case studies are also presented, demonstrating the benefits delivered by the system: The improved power management enables drilling long sections in a single bit-run.The higher data rate allows frequent pressure-while-drilling updates to help mitigate potential well control issues.Use of this system in combination with compression algorithms allows the delivery of real-time density image data of equivalent quality to recorded data.
The paper concludes by discussing further planned improvements to both downhole compression and surface detection techniques that will further increase the amount of real-time data that can be delivered, allowing operators to drill safely, fast, and on target.
Mathematical Modeling of Crack Proliferation at Pumping of Hydrofracture Liquid with Proppant into the Formation
Authors: Kashapov D. , Urmancheev S. 
Published: October 2015

Abstract
The presented work consists of two parts. In the first part there are questions about the definition of porous medium's filtration characteristics, the pressure of distribution, a layer's stress state on a field site. The following questions are considered: what is the size of the P-disruptive pressure; what is the dependence of the injection fluid from differential pressure after formation fracturing; how far does the induced break spread and what is the dependence of crack width and its volume from pressure drop across crack and layer; what is the influence of breakdown fluid's viscosity on the cracking mechanism and its sizes?
The hydraulic fracturing process is largely governed by the layer's stress condition. It is possible to define it knowing the ground pressure which is distributed among ground skeleton and liquid being in pores under the formation pressure. One of the problems that are necessary for definition of the layer's stress condition is the determination of reservoir pressure distribution.
In the second part of the work there is considering of hydraulic fracturing crack's formation at the well injection of thick liquid with particles impure. The characteristics of hydraulic fracture's development are observed under the different elastic and collecting properties of a layer and under prosperities of the hydraulic fracturing's agent in the injection modes.
Deviation from Planned Well Path through Accumulated Cutting Bed in High-Angle and Horizontal Wells – a Case Study in one Western-Siberian Oilfield
Authors: Yasin Naseri , Kulchitskiy Valeriy V. , Khormali Azizollah , Aygunian Valeriy V. , Borozdin Sergey O. , Afshari Moein Mohammad Javad 
Published: October 2015

Abstract
In recent years, thanks to telemetry systems, measurement while drilling and geo-steering technologies, drilling directional and horizontal wells has been improved significantly. But still there are a lot of complications in directional drilling operations. Cutting transportation is a serious challenge in high angle and horizontal wells. High mud flow rate is required to clean cuttings from the wellbore which is not always practically possible. High flow rates can lead to formation fracturing and result in mud loss. In addition, downhole motor's optimal fluid rate range may limit the value of fluid rate. In high-angle and horizontal wells, it is necessary to take into account presence of cutting bed as an inevitable fact and try to conduct all of the operation based on this fact. For example, while drilling horizontal or extended reach wells, it is not recommended to pull the drilling string out before cleaning the wellbore with high mud flow rate. Also, build rate must be calibrated based on cutting bed effect on bending moment and accordingly build rate.
In this work, the effect of cutting bed on build rate and deviation from the planned path for horizontal and highly deviated wells has been investigated. In "Rhinoceros" and "ANSYS", downhole elements shape, their characteristics and their interactions with each other have been simulated and analyzed. The simulation is done based on data from a real case in West-Siberian oil-field. Using Finite Element Method jammed cutting around the stabilizer have been modeled and its effect on wellbore deviation from planned path has been investigated. Jammed cutting has been simulated like a gravelly sand soil that increases the accuracy of the simulation. In the previous works, jammed cutting around stabilizer has been modelled as an increase in diameter that in this work, this assumption has been corrected.
Pressure Transient Analysis as a Tool to Estimate Efficiency of Underbalanced Drilling
Authors: Ibragimov N. G. , Iktissanov V. A. , Musabirova N. Kh. , Akhmadishin F. F. 
Published: October 2015

Abstract
Conventional or overbalanced drilling process is fraught with formation damage in the near-wellbore region because of drilling mud and cement slurry invasion, permeability loss attributed to change of the net reservoir stress, and other reasons. One of the ways to overcome negative effect of drilling fluid interaction with reservoir rocks is balanced or underbalanced drilling. This technology is however cash-consuming. The purpose of this work was to analyze the efficiency of underbalanced drilling compared with the conventional (overbalanced) technique. For the analysis, the results of pressure transient analysis (PTA) were used, which provide information about formation flow characteristics and effective drainage area in actual in-situ conditions. Performance of slanted and horizontal wells drilled in different geologic environment was analyzed. Main causes of underperformance were identified and selection criteria of well candidates for underbalanced drilling were justified.
Geophysical Monitoring of the Multilayer Reservoir with of Flooding and Induced Fractures Growth in the Injection Wells
Authors: Davletbaev A. , Zorin A. , Usmanov T. , Valiullin A. , Valiullin M. , Tikhonov I. , Fursov G. , Nazargalin E. , Slabetsky A. , Asalkhuzina G. , Ivaschenko D. 
Published: October 2015

Abstract
This paper considers the results of geophysical logging of multi-layer pumping wells with a bypass system of ESP units. Multi-layer production well testing with Y-tool assembly supports logging under commercial operation upon achievement of a steady-state flow regime.
Here, several formations within the field are being operated. Testing of flooding in a low permeability reservoir takes place when injection pressure is higher than the formation fracturing pressure of self-induced fracturing. Downhole logging in multi-layer wells with bypassing of ESP units is used to determine flooded formations where self-induced fracturing takes place. This approach is essential to plan activities to decrease water-cut in multi-layer production wells with injected liquid breakthroughs.
In the course of the study, certain field regions with considerable undrilled reserves were found in various formations. The risk of wellbores intersection with dynamically induced fractures in injection wells must be considered with regards to kick-offs of horizontal sidetracks and other well completions. This paper presents the results of numerical simulation using the reservoir model of a development element configuration with a long auto hydraulic fracture and several horizontal wells (HW) with multi-stage hydraulic fractures drilled perpendicular to a fracture in an injection well. Susceptibility to reservoir permeability, number of fractures in HW with multi-stage hydraulic fractures and a distance between fractures were analyzed.