bluuebunny/crossref_metadata_2025 huggingface dataset:
THE DETERMINATION OF DISTRIBUTION PARAMETERS OF ONE-DIMENSIONAL CONTINUOUS RANDOM VARIABLE ACCORDING TO ITS INITIAL CHARACTERISTICS BY FINANCIAL RISKS MODELLING
Authors: Dubnytskyi V. Y. , Skorikova І. H.
Published: July 2015

The conception of direct and inverse problem of random variable modelling is introduced. The direct problem is a problem for getting value of continuous random variable, which is contributed according to the given distribution law, which parameters are known. The inverse problem is a problem for defining the distribution law parameters, which are necessary for modelling of continuous one-dimensional random variable, for which the distribution law, mathematical expectation and dispersion are known. For its solution by known type of distribution it is necessary to find the parameter dependence of simulated distribution on set initial characteristics – ensemble average and standard deviation. The assigned problem is solved in explicit form for the following cases: normal distribution, exponential distribution, Laplace distribution, extreme value minimum distribution, extreme value maximum distribution, double exponential distribution, logistic distribution, gamma distribution, Erlang distribution of n-th order, Rayleigh distribution, Maxwellian distribution, parabolic distribution, Simpson distribution, arc sine distribution, inverse Gaussian distribution , Cauchy distribution, one-parameter distribution of n-dimansional random value, hyperexponential distribution, beta distribution, common- beta distribution, Birnbaum-Sanders distribution.For random variables, which are distributed according to the laws: Erlang second order, beta-distribution of second order, logarithmic normal distribution, it is described the interactive procedure to solve the modelling inverse problem, which realizes theNewton's method for solution of linear equation system. The expressions for elements of matrix solution are received. The solution procedure of assigned task for Weibull and Nakagami distribution is set, which is based on construction of regressive equations, which interpolate the table values to determine links of distribution law parameters and initial characteristics of random variable, which is distributed according to the given law.
УНІФІКАЦІЯ ОРГАНІЗАЦІЇ ТА МЕТОДОЛОГІЧНОГО ЗАБЕЗПЕЧЕННЯ ДІЯЛЬНОСТІ СУБ’ЄКІВ ФІНАНСОВОГО КОНТРОЛЮ У СТАНДАРТАХ
Authors: Lyubenko A. M.
Published: July 2015

У статті обгрунтовано важливість стандартизації організації та методологічного забезпечення діяльності суб’єктів контролю. Автором запропоновані підходи щодо уніфікації та стандартизації як організаційного так методологічного забезпечення діяльності суб’єктів фінансового контролю. В свою чергу автор наголошує що запровадження стандартизації основних етапів здійснення контролю за державними фінансами сприятиме підвищенню ефективності у витрачанні коштів та досягненні цілей які ставились при плануванні бюджетних витрат.
FISCAL CONSOLIDATION IN THE BALTIC STATES
Authors: Kasperowicz – Stępień A.
Published: July 2015

The strong growth performance of Baltic states, in the period 2000-07, was accompanied by rapid changes across the economy. Between 2004 and 2007 the Baltic statesstood among the EU countries for their high growth rate. The global financial crisis hit the Baltic statesmuch harder than other countries in the EU. In order to improve public finance sector were necessary radical consolidation. The aim of the article is to show the impact of the consolidation processes to improve the financial performance of the public finance sector.
АКТУАЛЬНІ ПИТАННЯ АНТИКРИЗОВОГО УПРАВЛІННЯ СТРАХОВОЮ ДІЯЛЬНІСТЮ В УКРАЇНІ
Authors: Shevchuk O. O.
Published: July 2015

У статті досліджено вплив кризових явищ на страховий ринок України, визначено найбільш значущі виклики його фінансово-економічній безпеці в сучасних умовах. Окреслено напрями реструктуризації страхового ринку України, необхідні для виживання в період кризи і подальшого розвитку. Обґрунтовано теоретичні підходи до антикризового управління страховою діяльністю та запропоновано антикризові заходи для страхового ринку України в сучасних умовах (як на рівні держави, так і на рівні страхових компаній).
Uncertainty, risks, income
Authors: Lerner Y. I.
Published: July 2015

The principles of accounting and estimations of probabilistic character of productive activity of enterprises, accepted in the methodology of accounting of uncertainty and risks, worked out by the author of this researches , are stated. The methodology is based on the fundamental postulates of probability theory, the theories of functions linearization and on the qualitative and quantitative technico-economical analysis in decision making are discussed. An example of the using this methodology with the solutions optimization is given. This methodology was adapted by the author over the past 10-15 years.
РОЛЬ ТА МІСЦЕ СПОЖИВАННЯ В ФІНАНСОВО-ЕКОНОМІЧНІЙ СИСТЕМІ
Authors: Shevchuk O. V.
Published: July 2015

У статті здійснено аналіз історичної еволюції теоретико-економічних поглядів на роль споживання та його місце в фінансово-економічній системі. Проаналізовано гіпотезу абсолютного доходу Дж. Кейнса; гіпотезу відносного доходу С. Кузнеця; модель міжчасового вибору І. Фішера; модель життєвого циклу Ф. Модільяні; модель перманентного доходу М. Фрідмена, модель дискретного вибору споживачів Д.-Л. Мак-Феддена та ін.
ОСОБЛИВОСТІ ВПРОВАДЖЕННЯ ЕЛЕМЕНТІВ СОЦІАЛЬНО-ОРІЄНТОВАНОГО МЕНЕДЖМЕНТУ У СИСТЕМУ ЗДОРОВ’ЯЗБЕРЕЖЕННЯ МАЙБУТНІХ ЕКОНОМІСТІВ
Authors: Zavydivska N. N. , Zavydivska O. I.
Published: July 2015

Проаналізовано науково-теоретичні і практичні засади необхідності впровадження механізмів управління здоров’ям у Вищій школі. Розкрито сутність методик виховання людської агентності, копінг-поведінки як IT-технологій соціально-орієнтованого менеджменту. Обґрунтовано необхідність модернізації методик формування культури здоров’я студентів, що є невід’ємним елементом корпоративної і управлінської культури майбутніх економістів.
The siren song of a sticky plant: Columbines provision mutualist arthropods by attracting and killing passerby insects
Authors: LoPresti E. F. , Pearse I. S. , Charles G. K.
Published: July 2015

Many plants provide predatory arthropods with food or shelter. Glandular trichomes entrap insects and may provision predators with insect carrion, though it has not been clear whether this putative benefit functions with natural amounts of carrion, whether plants actively attract insect “tourists,” and how common this provisioning system is. We tested the hypothesis that a sticky columbine (Aquilegia eximia: Ranunculaceae) attracts passerby arthropods (a siren song leading them to their demise); that these entrapped arthropods increased predators on the plant; and that these predators reduced damage to the plant. Sticky traps baited with columbine peduncles entrapped more arthropod carrion than unbaited control traps. Predator abundance correlated positively with carrion abundance observationally, and experimental removal of carrion reduced predator numbers. Experimental removal of carrion also increased damage to reproductive structures, likely due to reductions in predator numbers. This indirect defense may be common; we compiled a list of insect‐trapping sticky plants that includes over 110 genera in 49 families, suggesting a widespread convergence of this trait, even in non‐carnivorous plants. The ubiquity of this trait combined with these experiments suggest that carrion entrapment should be viewed as a common and active process mediated by the plant for indirect defense.
Complex Contaminated Gas Processing Made Simple
Authors: de Oude Matthijs
Published: July 2015

Processing of associated gas has often been considered to be economically non-viable due to the cost and complexity of the installations required to process the gas relative to the value of the gas recovered. The result is that the associated gas is often flared, however, with the growing emphasis on reducing green house gas and SO2 emissions, the processing and recovery of associated gas is becoming increasingly linked to development and maturation of oil reserves.

In some locations the associated gas contains H2S, CO2 and organic Sulphur species, and historically the treatment of these complex gases has required multiple steps to remove the different contaminants. In addition, as the acid gas produced is of low quality, further processing in an acid gas enrichment unit is required to enable recovery of the Sulphur in a traditional Claus and SCOT unit combination. In cases where less than approximately 50 metric tonnes of Sulphur per day is produced, the result can be a relatively complex, costly and energy-intensive process facility.

This presentation describes how Shell has significantly simplified the processing of a complex contaminated associated gas mixture by using an innovative combination of two already proven technologies: Sulfinol-X for integrated all-in-one contaminant removal, and THIOPAQ O&G for biological, single step, low tonnage Sulphur recovery without the requirement for acid gas enrichment.

The strength of this solution lies in the combination and integration of the two technologies. The relevance to the industry is that it enables contaminated, associated gas to be monetized, green house gas reductions to be achieved and oil reserves to be developed in a cost-efficient manner.
Detecting and Correcting Pipeline Leaks Before They Become a Big Problem
Authors: Cramer Ron , Shaw David , Tulalian Robert , Angelo Pabs , van Stuijvenberg Maarten
Published: July 2015

Timely pipeline leak detection is a significant business issue in view of a long history of catastrophic incidents and growing intolerance for such events. It is vital to flag containment loss and location quickly, credibly and reliably, for all green, brown field critical lines in order to shut down the line safely and isolate the leak. Pipelines are designed to transport hydrocarbons safely; however, leaks have severe safety, economic, environmental and reputational effects.

This paper will highlight robust, reliable and cost effective methods, most of which leverage real time instrumentation, telecommunications, SCADA, DCS, and associated online leak detection applications.

The purpose of this paper will be to review the underlying Leak Detection business issues, catalogue the functional challenges and describe experiences with available technologies. Internal and External techniques will be described, including basic rate of change of flow and pressure, compensated mass balance, statistical, real time transient modeling, acoustic wave sensing, fiber optic cable (distributed temperature, distributed acoustic sensing) and subsea hydrophones. The paper will also describe related credibility, deployment, organizational and maintenance issues with an emphasis on upstream applications.

The scope will include leak detection for pipelines conveying various flowing fluids – gas, liquid and multiphase flow. Pipeline environments will include subsea and onshore.

Advantages, disadvantages and experiences with these techniques will be described and analyzed.
Thermodynamic Description of Organic/Inorganic Interactions in TSR Reservoirs
Authors: Richard Laurent , Uteyev Rakhim , Peters Henning
Published: July 2015

Although thermochemical sulfate reduction (TSR) is an irreversible process, it can be demonstrated that many reactions involved in TSR occur at or near equilibrium. This applies not only to minerals and formation waters, but also to hydrocarbons and organic sulfur compounds (OSC) in crude oils and condensates. The metastable equilibrium approach pioneered by Helgeson et al. (1993) is here extended to construct a thermodynamic model of TSR which allows to calculate compositional changes in the water-rock-hydrocarbon-gas system as a function of reaction progress. Using oxygen fugacity as a redox variable to describe the stability relations among minerals, formation waters, and hydrocarbon and organic sulfur species in petroleum, it is shown that the redox state of the water-rock-hydrocarbon-gas system progressively shifts with increasing reaction progress from reduced conditions (under which petroleum is stable), towards more oxidizing conditions imposed by the anhydrite-calcite-sulfur assemblage (and under which pyrobitumen and elemental sulfur may form). This change in redox conditions during TSR appears to be consistent with the observed increase in the aromatic fraction of crude oils during TSR. The results of the speciation calculations compare favorably with compositional data reported in the literature for reservoired oils affected by TSR. Geochemical parameters which have been compared include saturate/aromatic ratios, organic sulfur contents, and concentrations of dibenzothiophenes of crude oils, as well as the CO2/H2S ratio of the gas phase.
Process Safety Information Management
Authors: Okshiev Askhat , Alteneder Will
Published: July 2015

OSHA Process Safety Management Program refers to a set of requirements for managing hazards associated with the processes using highly hazardous chemicals, such as toxic, reactive, flammable or explosive substances. The current hydrocarbon production and processing technologies make Process Safety Management (PSM) Program a critical component for safe operation of refining ventures and gas processing plants.

Process Safety Information (PSI) can be considered the keystone of PSM Program. In order to be in compliance with the OSHA PSM Program the process safety information shall include:

Information pertaining to the hazardous chemicals used or produced by the process; Information pertaining to the process technology; Information pertaining to the equipment in the process.

The objective of this paper is to demonstrate that Tengizchevroil effectively manages some of the Process Safety Information key components at Tengiz field (Kazakhstan) to ensure safe and controlled field operation, as well as to share lessons learned.
New Application of Streamline Simulation for Gas Displacement Processes
Authors: Nagib Mohamed , Burns Alan , Ingham Derek , Pourkashanian Mohamed , El-Banbi Ahmed H.
Published: July 2015

Performance evaluation of miscible and near-miscible gas injection processes is available through conventional finite difference (FD) compositional simulation. The Finite-difference method is widely used for solving large-scale multiphase displacement problems (e.g. displacement of oil by water/gas in heterogeneous petroleum reservoirs). While FD simulation has many advantages, it also suffers from some disadvantages. These include numerical dispersion, grid orientation, small time step size and excessive computation time. However, and specifically for compositional simulation, low-resolution compositional simulation is adversely affected by numerical dispersion and may fail to represent geological heterogeneities adequately, while high-resolution simulation may be expensive in computation time. The number of fluid components can possibly be reduced but only at the price of less accurate representation of phase behavior.

Streamline methods have been developed in which fluid is transported along the streamlines instead of the finite difference grid. In streamline-based simulation, a 3D flow problem is decoupled into a set of 1D problems solved along streamlines, reducing simulation time and suppressing any numerical dispersion. Larger time steps and higher spatial resolution can be achieved in these simulations. Streamline-based reservoir simulation, being orders of magnitude faster than the conventional finite difference methods, may mitigate many of the challenges noted above.

In this paper a detailed comparison is given between the results of conventional FD simulation and the streamline approach for Gas Displacement processes (including miscible processes). Different sensitivities on several resolutions of the dynamic grid is presented. Finally, guidelines are given on how streamline can be potentially used to good effect for Gas displacement processes.
Tengiz Well Performance Forecasting Using Wellbore Transient Flow Modeling
Authors: Ekweribe Chiedozie , Choi Suk Kyoon , Dunger Darrin , Macary Sameh , Howery Randy , Popp Nick , Svyatov Aidar
Published: July 2015

The Tengiz field is a giant oil field producing 530 thousand BOPD from about 70 naturally flowing wells. Continued reservoir pressure depletion and the current surface gathering system pressure have necessitated the need for better prediction of the onset of liquid loading and consideration of mitigation strategies. Active surveillance programs and system integrity efforts have contributed to frequent well shut-ins and some challenges during well restarts. Additionally, the flow back of higher density drilling and completion fluids is becoming more difficult, especially in low pressure areas of the field, and in wells experiencing large fluid losses during drilling or workover.

Steady-state tools are used extensively for well modeling and production forecasting in Tengiz, with historically good results. However it was realized that the steady-state models would be unable to predict unstable production behavior expected to come with continued reservoir pressure decline. Hence, the asset team decided to use a transient flow simulator for a better understanding of these conditions.

This paper describes the selection of the candidate wells, calibration and validation of the transient models and the design of a representative ‘hypothetical’ well which was used to evaluate the minimum conditions for well flow during normal well operations as well as restart pressures post well shut-ins. The impact of various factors including wellhead pressure, productivity index (PI), reservoir pressure, water cut, gas-to-oil ratio (GOR), tubing size and well deviation on loading conditions were evaluated. The study results have provided invaluable information to evaluate mitigation options for liquid loading.
Screening Different Water Alternating Carbon Dioxide Injection Scenarios to Achieve to the Highest Macroscopic Sweep Efficiency in a Non Fractured Carbonate Reservoir
Authors: Bagrezaie M. A. , Pourafshary P.
Published: July 2015

Miscible gas flooding using carbon dioxide provides us excellent microscopic displacement efficiency in different mature oil fields. Due to the limitation of CO2, optimization of CO2-EOR process to reach to the best macroscopic sweep efficiency is an essential problem. Unfavorable mobility ratio and gravity segregation lead to viscose fingering and gravity override. Hence, areal and vertical sweep efficiencies decrease due to the early breakthrough of the injected gas. Different approaches are applied to change the injection scenario of the gas to control the mobility ratio and gravity effects. A comprehensive approach is needed to select the best scenario and optimize it to achieve the highest recovery in an economical manner.

Different scenarios of water alternating carbon dioxide injection such as TWACO2 (Tapered Water Alternating CO2), WACO2 (Water Alternating CO2), SSWACO2 (Selective Simultaneous Water and CO2), and SWACO2 (Simultaneous Water and CO2) can be selected as candidates for the EOR operation. In this work, these scenarios were simulated and studied for a non-fractured reservoir. The simulation outcomes were coupled by an economical model and compared to the pure water and CO2 injection to specify the appropriate and optimized injection method to gain to the highest Net Present Value. Hence, by this method, the necessary amount of the injected gas and water were also optimized for the best scenario. By our simulations, we found that SWACO2 injection increased the total recovery compared to the primary recovery by 25.4 percent which was the highest. The achieved NPV was lower for this method compared to TWACO2. Hence, we recommended TWACO2 as the best method and we optimized it for application in the field.
Experimental Investigation of Gas Lift Instability and Dynamic Regulation to Control It
Authors: Larsen Christer Andre , Asheim Harald Arne
Published: July 2015

The idea explored is that gas lift may be stabilized by imposed oscillations. This has been experimentally investigated in a scaled-down facility where water is lifted by air. An air-tank provides compressibility emulating a gas filled annulus. Depending on pipe dimension, injection rate and tank volume, the flow may be stable, or oscillate similarily to casing heading in full-size wells.

To control natural oscillations, their dominating frequency was firstly determined. Destructive interference was then imposed by cyclic variation of either the downhole injection valve, or the tubing outlet valve. By injection valve regulation, the flow was stabilized and 40% higher liquid rate obtained. Outlet choke regulation also stabilized the flow, but rate improvement less, up to 13%.

Scaled-down facilities should be viewed with sobriety. However, the facility appears to exhibits static and dynamic behavior similar to real wells, so the experimental results may be lent some credibility. This may provide a new and simpler approach to control of gas lift instability.
Karachaganak, Integrated Reservoir Studies on a Giant Field
Authors: Albertini C. , Bigoni F. , Cominelli A. , Della Rossa E. , Francesconi A. , Tarantini V.
Published: July 2015

Karachaganak Field, a Permo-Carboniferous carbonate platform, is a retrograde gas-condensate-oil reservoir located in the Pricaspian Basin. The field, in production since 1985, holds about 9 Bbls of oil and gas condensate and 48 Tcf of natural gas. Historically, the reservoir properties distribution has been debated because of both the complex depositional setting and the strong diagenetic overprint. These uncertainties have been assessed in the present study by analyzing and integrating the vast amount of geological and production data with the target of building a history matched reservoir model.

Seismic facies analysis, integrated with analogues outcrop and core and log data, reveals different geological contexts that ranges from platform interior bedded deposits to aggrading mounds, prograding clinoforms, slopes and basin sediments. Different Depositional Regions, characterized by specific petrophysical characteristics, as estimated from core, log, Well-Tests, PLT and production data, were defined.

The study, performed through an iterative process between geological and numerical models, allowed the definition of geologically meaningful interpretations of the complex dynamic behaviors. Different critical issues were better addressed by Depositional Region: quantity and magnitude of the enhanced permeability related to micro-fracturing and vugs, rock matrix permeability scale factors from plug to whole core, geological meaning and impact of sealing barriers, dolomite estimation and modeling, mound size range and modeling. A "best estimate" reference model has been thus defined and a very good history match achieved.

The uncertainties of the field have been then investigated considering the achieved history match as the benchmark. Starting from the reference model the petrophysical characteristics of the different Depositional Regions have been changed far from the history matched wells at an estimated threshold distance not perturbing the history match. Low and high scenarios models were thusly defined. These represent possible alternative "end members" consistent with the geological data and still endorsed by the history match.
Characterization and Modeling Challenges Associated with Fracture and Karst (Non-Matrix) in the Margin Area of a Carbonate Reservoir
Authors: Medekenova Alfiya , Jones Gareth D.
Published: July 2015

Non-matrix features in the margin area of a carbonate reservoir contribute significantly to field in-place volumes, production rates, and recovery. These features vary in size and shape, but exhibit distinct behavior compared to tight matrix rock. Nonmatrix features such as karst can provide significant storage capacity, and well-connected fractures provide high deliverability. These characteristics make production from the margin area attractive. However, extreme heterogeneity of non-matrix features increases uncertainty and requires complex analysis involving data interpretation, advanced characterization, and sophisticated modeling in order to estimate future production performance.

During the initial field development stage, data interpretation is frequently limited by data acquisition capabilities. Data collection associated with non-matrix features can be challenging, often leading to less than optimal data sets. The scale difference among data gathering techniques further increases the gap between interpretation and full-field modeling. Data integration, along with the use of analogs and concepts, helps to bridge data gaps and improves confidence when modeling field-wide non-matrix heterogeneities.

Advanced approaches, such as dual porosity / dual permeability dynamic modeling enhance ability to evaluate both matrix and non-matrix properties. Once developed, the model is calibrated by comparing simulation results to available dynamic data. As part of the modeling workflow, uncertainty analysis is conducted to identify and evaluate key reservoir properties that could impact in-place volumes and ultimate field recovery. Through collaboration and integration of geoscience and reservoir engineering workflows, it is possible to create a well characterized and calibrated model that is capable of testing key uncertainties against a range of development concepts.
Do Not Let Temperature Transients Hinder Your Build-up Pressure Interpretation – Proper Gauge Placement in Highly Productive Reservoirs in Well Testing Operations
Authors: Sidorova M. , Theuveny B. , Pimenov V. , Shako V. , Guzman-Garcia A. G.
Published: July 2015

Quality of well testing in highly productive reservoirs directly depends on the pressure-gauge placement in the wellbore. This paper documents the impact of the placement of downhole gauges on pressure transient analysis (PTA) for high-productivity reservoirs. The article illustrates cases where this late-transient behavior is strongly influenced by temperature effects, which can lead to significant errors if not considered during the interpretation process.

Although the correction of measured pressure to datum is possible by proper modeling of the influence of non-isothermal effects on the test string and the produced fluids caused by temperature changes, it is preferable to avoid this situation by suitable gauge placement. This greatly facilitates a more accurate interpretation of data using PTA with a reduced uncertainty in the definition of the appropriate reservoir model to use. Proper modeling during the test design of these temperature effects on the correction of pressure to datum also allows the determination of the resulting uncertainty pressure variations and the selection of the optimal test-string design, with consideration made to the expected temperature changes, fluid present in the wellbore, and range of productivity. Reconstruction of pressure is also possible despite a high level of resulting uncertainty.

A workflow for reconstruction of pressure data taking into account temperature effects is proposed. We emphasize that such corrections cannot substitute the correct pressure measurement for successful well-test data interpretation. Present gauge technology allows proper test design and correct placement of pressure and temperature gauges in close vicinity of the interval of interest, to avoid or minimize potential problems related to the reconstruction of the measured pressure to datum.
An Improved Method for Estimating Volumetric Sweep Efficiency of Low Salinity Water Injection
Authors: Al-Shalabi Emad W. , Sepehrnoori Kamy , Pope Gary
Published: July 2015

This paper investigates the effect of low salinity water injection (LSWI) on both oil displacement and volumetric sweep efficiencies. A new definition of mobility ratio is proposed and shown to correlate with volumetric sweep efficiency better than other definitions in the literature. A quarter 5-spot field model was created by upscaling recently published coreflood experiments. Simulations were performed using the empirical low salinity injection model implemented in the UTCHEM simulator. The volumetric sweep efficiency for various seawater dilutions was estimated by adapting a fractional flow method and a tracer method for this purpose. The fractional flow method and the tracer method were consistent in estimating the volumetric sweep efficiency. Moreover, an improved estimation of volumetric sweep efficiency was possible with the proposed mobility ratio definition, which applies in the tertiary mode and physically makes more sense compared to other definitions in the literature. In addition, the maximum incremental oil recovery was achieved at the 10 times diluted seawater injection cycle with is consistent with other studies in the literature. Next, the injected number of pore volumes for each of the seawater dilutions was optimized. The optimum was found to be two pore volumes of injected seawater dilutions.
Application of the Extended Dynamic Material Balance Method to a Super Giant Carbonate Oilfield
Authors: Istayeva Ultay , King Gregory
Published: July 2015

In this paper, we discuss the use of the dynamic material balance (DMB) method to a super-giant carbonate oilfield. The principal advantage of the DMB method, in contrast to the conventional material balance (CMB) methods, is that well shut-ins are not required for the application of the DMB method. While the fundamental assumptions of material balance are still applicable, we extend the DMB method described in the literature in several important ways. These extensions include:

The use of pressure dependent oil formation volume factor (FVF), Bo, including a pressure dependent oil compressibility, co The use of pressure dependent (net effective confining stress) formation compressibility, cf The use of a revised method for estimation of the original-oil-in-place, OOIP

Due to the significance of a super-giant oilfield to the operator's portfolio, well shut-ins are routinely performed in the field and stabilized, static shut-in pressures, though not required for the application of the DMB, are commonly collected. Consequently, we are in a position to compare the results of the DMB predicted pressures to field measured pressures. In general, these comparisons are very favorable, and they will be presented and discussed in the paper.

In addition to the use of the DMB for original-oil-in-place (OOIP) estimates, we have observed that trends in the DMB plots can be used to diagnose pre-/post- workover performance. Therefore, we can use the DMB method to determine the success/failure of well interventions for improving the well productivity and for adding connected in-place oil to the wellbore. Our experience with this application of DMB will also be discussed in the paper.

Finally, we use this paper as a case study for the application of the DMB method to a producing oilfield.
A Case Study on Optimization of PCP Operations for Production Increase in an Unconsolidated Sandstone Reservoir
Authors: Netzhanova Akmaral , Bae Wisup , Arystanbay Rustem
Published: July 2015

The ZH field located in Kazakhstan is comprised of shallow, unconsolidated sandstone reservoir that is being produced medium sandy oil by the help of progressive cavity pumps (PCP). The nature of unconsolidated reservoir makes overall production inefficient; due to sand production being a major concern in the field. High frequency of workover operations and limited productivity of wells were caused by sand production. Moreover, pump seizure happens more often because of the low fluid velocity, there is sand inside the production wells can not move up to the surface.

The goal of this study is to increase oil production by optimizing the progressive cavity pumps operation. Improving production requires minimizing workover frequency, therefore sand should be lifted out of the well continuously with the fluid. This can be achieved by controlling the ratio of the actual fluid velocity to the sand settling velocity. The fluid velocity in the tubing should be enough to lift most of the produced sand particles from the bottomhole of a well.

The statistics showed that production wells with fluid velocities of 75% of sand settling velocity or less were likely to have pump seizure with the lack of sand carrying capacity in the tubing. By increasing pump size, modifying tubing size, and increasing pump rotation per minute (RPM), PCP performance was significantly improved. This paper shows the significance of the parameters stated above.

Field cases in PCP optimization are summarized. The successful cases highlight an incremental oil production of 126 m3/d with seldom workover. Unsuccessful cases were characterized by often and sudden pump seizures with increased watercut. This study has shown that maintaining production rate through PCP operation coupled with continuous sand lifting is more beneficial than controlling the sand production such as installing gravel packs.
Vertical Reservoir Connectivity Evaluation in Dunga Field, Albian Horizon
Authors: Zhumekeshov A. , Elbattawy A.
Published: July 2015

All Dunga field wells to date have been producing from a low permeability sandstone reservoir of Aptian age. However, while drilling an exploration well, formation evaluation revealed the existence of hydrocarbons in a shallower horizon (Albian) which was not known to be hydrocarbon bearing in the Dunga area. This raised a need to further appraise the accumulation and reduce geological uncertainties.

In this paper we discuss the unique properties and uncertainties that will affect future development of the Albian reservoir, and present results from a detailed wireline logging program, fluids pressure-volume-temperature properties, and extended well testing results to evaluate the hydrocarbon find in order to reduce those uncertainties.

Conventional interpretation of petrophysical logs was complemented by wireline formation testing (WFT) pressure data and formation fluid samples. The laboratory analysis of hydrocarbon samples is compared to real time downhole optical analysis of formation fluids.

Additionally, pressure transient analysis (PTA) from WFT was compared to conventional PTA results from DST completed well testing, in order to help understand the vertical permeability profile.

We also propose additional future work to complement the work presented in this paper by suggesting a vertical interference test and well-to-well data evaluation.

All these studies will help to answer key decisions on developing an Albian reservoir which has no analog in this region.
Scaling Gravity-Drainage Oil Recovery from Fractured Reservoirs Using 3D Discrete Fracture Models
Authors: Hui Mun-Hong (Robin) , Heidary-Fyrozjaee Mohsen , Kamath Jairam
Published: July 2015

Gravity drainage caused by density difference between fluids in the fractures and in the matrix rock can be an effective mechanism for recovering oil from naturally fractured reservoirs (NFRs). This process has been studied in the past, and oil-recovery-rate scaling laws that depend inversely on matrix block height have been developed.

In this work, we show that these scaling laws are only valid for one-dimensional flow where fracture spacing is small compared to matrix block height. We use single-element mechanistic fracture models and discrete-fracture-matrix (DFM) models of realistic systems to develop new scaling relationships that better capture 3D gravity drainage in weakly wetting realistic NFRs. The single-element models reveal that the gravity drainage rate scales as a function of both fracture spacing and matrix block height, and not only on the inverse of matrix block height as previous investigations suggested. This has implications for maximum gravity-drainage rates that are possible in fractured reservoirs—either through the geological distribution of heterogeneities or through operational control of the fluid-height difference in the fractures and matrix. We also create detailed DFM models for geologically realistic fracture networks that result in a spatially variable distribution of fracture spacing and matrix block height, and describe how to scale gravity drainage in such systems.
Application of Polymer Gellan for Injectivity Profile Leveling
Authors: Gussenov I. Sh. , Ibragimov R. Sh. , Satpayev K. I. , Kudaibergenov S. E. , Satpayev K. I. , Abilkhairov D. T. , Kudaibergenov D. N
Published: July 2015

This work describes the results of laboratory experiments carried out on core samples and sandpack models as well as the field pilot tests conducted in October 2013 on 2 injection wells of Kumkol oilfield. The reduction of the permeability of porous space was achieved by injection of gellan solution, gelation of which is initiated by the following cations: Ba2+, Са2+, Мg2+, K+, Na+, containing in brine water. On the basis of laboratory experiments the suitable concentrations of polymer reagent for the pilot tests were selected. A series of laboratory experiments were carried out to reduce the amount of polymer reagent without detriment to the efficiency of the technology. Also the mixtures of polysaccharides gellan and xanthan in the weight ratios 1:2; 1:1; 2:1 were found to be more effective in comparison with separate components. One of the main features of this work is that polysaccharide gellan was used for the first time in oil industry, thus new application frontier for this polymer was found. The most remarkable feature of the proposed polymer is due to its gelation after contacting with brine water so no additives are needed to initiate the gelation process inside of the oil formation in contrast to polyacrylamide gels crosslinked by chromium ions which are widely used for conformance control operations.
Optimization of Well Hydraulics for Riserless Deepwater Drilling Operations under High Temperature and High Pressure Environment
Authors: Patel Akshit , Chaudhari Ravi , Deendayal Pandit
Published: July 2015

World's energy demand is on upsurge and Oil & Gas industry has been directed towards the exploitation of deepwater oil and gas resources. To make this operation successful petroleum industry is continuously demanding new innovative drilling technology that can be easily implemented. One of the constraints that hinders the deepwater exploration is its continuously shrinking narrow window between pore pressure and fracture pressure that further limits the reliability of old conventional riser drilling technique.

Dual gradient drilling (DGD) is a managed pressure drilling that involves use of two different annular fluids for drilling a prospect providing a favorable annular pressure profile and simpler, safer & economical well design.

In any of the rotary drilling operation, drilling hydraulics is the most complicated and least understood drilling variable as it involves complex relationship between drilling fluid, drill bit and formation. Riserless drilling, one of the type of DGD, eliminates the use of marine riser (u-tube is imbalance) and involves use of an additional subsea mud pump at seabed which, supplements to the complication for hydraulics computation as compared to conventional drilling.

In drilling HPHT deepwater wells, drilling fluid is constantly exposed to its own column pressure and formations geothermal gradient which subsequently affects the mud rheology and density. These altered rheological parameters leads to inadequate hole cleaning and lowers the drilling efficiency. High temperature in the wellbore cause's fluid expansion and high pressure causes fluid compression and these changes get extremely severe as water depth and drilling depth increases. Hence it becomes necessary to consider the HPHT effects on Equivalent Circulating Density (ECD) and to correct & optimize the hydraulic program to ensure the best utilization of the hydraulic energy for effective hole cleaning.

This paper presents a detailed study of Well hydraulics for riserless drilling considering the HPHT effect on Equivalent Circulating Density and its optimization so as to ensure riserless drilling operation is conducted in safe and effective manner. Also the paper is concluded with some recommendations on operational and design strategies.
Tight Sandstone Reservoir Renaissance: Baimiao Gas Condensate Field
Authors: Miao Heping , McBurney Cameron J. , Wu Xinrong , Wei Ruiling , Zhao Yuxin
Published: July 2015

Gas condensate has become very important because the liquid makes it a high-quality hydrocarbon fluid. Tight gas condensate reservoirs may contain large reserves, but can be extremely costly to develop. The Baimiao gas condensate reservoir is a deep, structurally complex, low- permeability play with a high condensate yield.

This kind of tight gas condensate reservoir encounters many challenges in its exploitation, especially well bottom-hole liquid dropout. Many of the producing wells in the Baimiao tight gas field do not naturally produce the liquids that dropout in-situ around the wellbore. Thus, it is imperative that innovative and effective technologies are applied to lift the condensate-collecting bottom-hole, ultimately prolonging the life of the well and improving the reservoir gas recovery. The techniques used include liquid drainage with narrow tubing, a newly designed plunger gas-lift with a skid-mounted gas-lift, and an interstitial gas-lift.

During the last five years, the Baimiao operator team used integrated gas-lift technology and fine operating procedures to produce the gas condensate. The primary objective of this paper is to advance the understanding of multiphase flow production within tight gas condensate reservoirs. To achieve the objective, a series of closed-gas-lift techniques for field application were introduced; the results from the application of the techniques are presented. Field example summaries are presented at the end of the paper.
A New Early Warning Model with Vector Machine for Abnormal Production Prediction
Authors: Li JunJian , Jichen Zhao , Hanqiao Jiang , Wenchao Fang , Hongxia Liu , Wu Xiao
Published: July 2015

Some mature reservoirs in China are encountering a sharp production decline, indicating a near-bleak production stabilizing prospect. Production fluctuation is essentially a phenomenon with a variety of affecting factors. An effective monitoring method has become a must with urgency for high water cut reservoirs. The existing development analyzing method or warning method is merely restricted to some particular indicator regarding development dynamics. However this kind of mechanism cannot be responsibly extended to continental deposited formations with strong heterogeneities for a lack of reliability and accuracy. In a reservoir engineering standpoint, all fluctuation in production can be feasibly traced from corresponding development dynamics indicators, which can change accordingly. Thus it is possible production change might be foreseen or predicted through analyzing the abnormal variations in indicators. We may start up analysis with oilfields and oil production plants owning sharp production variations, probe the causes behind and find the reflective indicators from 47 reservoirs. Our study has come up with a total of 10 perspective indicators for early warning, for instance, previous year oil rate ratio of new wells, ratio of oil rate from production enhancement, production injection ratio, enhancement efficiency and measurement Shortage, and the like. Various comparison and assessment standards are viable for different indicators. Oil production variations are further categorized into abnormal, normal, and better scenarios after evaluating uni-indicator using methods of plan comparison, trend comparison and history comparison without a neglect on individual indicator performance. Based on conventional warning strategies, a fresh early warning model with vector machine is devised. We apply this new model to 12 reservoirs in Shengli oilfield. Over 90% of abnormal production variations are successfully detected by this model through analyzing their nearly 20-year production history, yielding a practically good predicting accuracy and showcasing a big promise in effective monitoring for oil production.
Advances in Numerical Modeling of Downhole Dynamics for Perforated Well Completions
Authors: Bale Derek , Ji Minsuk , Satti Rajani , Gilliat Jim
Published: July 2015

Perforation operations are an important part of the well completion process in many field developments today. However, there are two considerations paramount to such a design. First, the post-job well production rate depends critically on a complex system in which the formation, perforations, and wellbore are dynamically and nonlinearly coupled together. Second, perforating operations can place a large dynamic load on downhole equipment. Predicting the spatial loading and its transient behavior is an important step in a completion design that implements risk mitigation to avoid damaging downhole equipment. In this study, we use a numerical modeling tool that has been used to simulate the dynamic behavior of the wellbore-reservoir system during perforating pre-job design. A typical case for this modeling software generates a quantitative prediction for the transient distribution of pressure, mass, velocity, and energy from the perforating event. These transients are commonly analyzed and incorporated into completion designs.

In this paper, two critical components of modeling relative to perforating job design will be evaluated and characterized. First, the wellbore-perforation-formation coupling will be evaluated and characterized using a modified version of the code designed to model API RP-19B Section IV flow testing. Section IV experimental data will be compared to numerical predictions. We present successful predictions of pressure transients that match experimental data. The second component of the software evaluated and characterized in this paper is the pressure, volume, temperature (PVT) accuracy and its implementation. NIST thermodynamic data, together with shock tube examples with pressure and temperature ranges relevant for deep-water completions will be used. We demonstrate that, although the current PVT implementation is accurate on typical downhole jobs, it could have limitations at higher pressures and temperatures. Finally, we present an improved numerical implementation for the modeling software.
Microannulus and Cement Evaluation: Effectiveness of Cement Evaluation Using Sonic and Ultrasonic Technologies in Wells with Microannulus Between Casing and Cement Sheath
Authors: Timonin Andrey , Lungershausen Dirk , Kravets Petr
Published: July 2015

Detailed cement evaluation with good azimuthal coverage is paramount for many wells in Chinarevskoe field, western Kazakhstan, as it affects perforation placement for acid treatment of thinly layered formation that is very heterogeneous, with varying permeability, reservoir pressure and water saturation. Analysis in these wells is performed not only to evaluate cement quality, but also to relate it to casing centricity with respect to formation or outer casing walls to help reaching objectives for cementing jobs in future wells.

Cement evaluation with wireline tools is one of the primary means for determining whether the objectives of a cementing job have been reached once the job is finished. Several logging techniques are currently available for measuring cement quality, including sonic cement bond logs (CBL) and ultrasonic logs. These logs are affected by a microannulus to various extents, and this can make a big difference in our interpretation of cement placement quality.

The sonic CBL and ultrasonic imaging log were run to evaluate cement quality in wells in Chinarevskoe field. Most of the wells exhibit the presence of a microannulus between the casing and cement sheath that develops just after the cementing job is completed. We observe that sonic CBL logs are affected by the presence of the microannulus. Cement evaluation is further complicated by the presence of contaminated cement where the acoustic impedance of the mud is close to the acoustic impedance of the contaminated cement. In these wells, a new generation cement evaluation service with enhanced ultrasonic measurements was deployed. A comparison of the results with traditional ultrasonic and sonic measurements shows that analysis of the enhanced ultrasonic logs improves cement evaluation in the presence of microannulus.