bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Transient Coupled Wellbore-Reservoir Model Using a Dynamic IPR Function
Authors: Garcia A. Posenato , de Sousa P. Cavalcanti , Waltrich P. J. 
Published: September 2016

Abstract
Conventional IPR models are used in coupled wellbore-reservoir transient simulations, even if bottomhole pressure conditions are assumed to be constant on the derivation of such IPR models. The dynamic IPR model proposed in this paper not only captures the relevant reservoir dynamics from the well perspective, but is also computationally more efficient than discretized models using hundreds of gridblocks to simulate the near wellbore region.
Any well-behaved function can be decomposed in a combination of sinusoidal functions. Hence, a sinusoidal bottomhole flowing pressure with a frequency varying from a given value down to zero is assumed as a boundary condition to the hydraulic diffusivity equation. The zero frequency corresponds exactly to the conventional IPR model since it is the steady-state condition. The analytical solution that calculates the flow rate for the sinusoidal pressures for each one of the frequencies is presented. Finally, the Dynamic IPR is defined as the low-order, linear ordinary differential equation that best approximates this solution.
It is a well known fact that the reservoir dynamics is relevant to the calculation of the flow rate in certain conditions, such as drawdown and pressure buildup well tests. A comparison between the Dynamic IPR function, the conventional IPR models, and the analytical solution is presented for these cases. The conventional IPR model gives unrealistic results, since it allows the flow rate to change instantaneously to the next equilibrium condition, as opposed to the Dynamic IPR which can capture the fully transient response. The Dynamic IPR showed excellent agreement with the true solution. Two different examples are presented in this paper showing the application of the Dynamic IPR: a reservoir well testing and a severe slugging well. With a given measured bottomhole flowing pressure, a comparison between the Dynamic IPR, conventional IPR and a reservoir simulation is presented. Once again, the conventional IPR model provides unsatisfactory results when compared to the Dynamic IPR. These results showed that neglecting reservoir dynamics in transient simulations might result in inadequate production forecasts, inefficient designs and eventually unsafe operations while using conventional IPR models.
This work points out some limitations in one of the common practices in the industry, which is the use of steady state IPR for coupled wellbore-reservoir transient simulations. The alternative Dynamic IPR herein proposed is computationally inexpensive when compared to discretized reservoir models while still being able to capture the transient well behavior and the steady-state solution.
An Assessment of the Probability of Subsurface Contamination of Aquifers from Oil and Gas Wells in the Wattenberg Field, Modified for Water Well Location
Authors: Stone C. H. , Fleckenstein W. W. , Eustes A. W. 
Published: September 2016

Abstract
The United States National Science Foundation has funded a Sustainability Research Network (SRN) focused on natural gas development in the Rocky Mountain region of the United States. The objective of this specific study is the assessment of the use of existing water wells to monitor the risk of the contamination by the migration of fracturing fluids or hydrocarbons to fresh water aquifers. An additional objective of the study is to modify existing risk estimates using the spacial relationships between the existing water wells and producing oil wells. This will allow estimates of single barrier failure and multiple barrier failure resulting in contamination to be projected for oil and gas wells in areas without surrounding water wells to detect migration, based on well construction type.
Since 1970, the Wattenberg Field in Colorado has a large number of oil and gas wells drilled. These wells are interspaced tightly with agricultural and urban development from the nearby Denver Metropolitan area. This provides a setting with numerous water wells that have been drilled within this area of active petroleum development. Data from 17,948 wells drilled was collected and analyzed in the Wattenberg field, allowing wells to be classified by construction type and analyzed for barrier failure and source of aquifer contamination. The assessment confirms that while natural gas migration has occurred in poorly constructed wellbores is infrequent, it can happen and that the migration risk is determined by the well construction standards. The assessment also confirms that there has been no occurrence of hydraulic fracturing fluid contamination of fresh water aquifers through wellbores. The assessment determines both the spacial proximity of oil and gas wells and surface casing depth to water wells to determine the utility of water wells to monitor migration in oil wells.
Role of Fluid Injection on Fault Activation During Hydraulic Fracture Stimulations
Authors: Baig Adam , Urbancic Ted , Viegas Gisela 
Published: September 2016

Abstract
Based on recent reports, there is little doubt that hydraulic fracturing can result in the generation of seismic events with magnitudes greater than zero as related to the activation of faults situated within or within proximity to reservoirs. The question that arises is whether fault activation is related to the presence of fluids and proppant or is related to perturbations in the local stress field. In other words, are these events triggered through stress perturbations or induced by pore pressure reducing effective stress?
Fault activation is also related to the degree of surface roughness, asperities and barriers to slip, frictional stress of the rock and the resulting rupture velocity. To derive a picture of the faulting and sub-faulting processes, we examine signals of a M&gt;0 event associated with stimulation in the Marcellus formation as recorded near surface with low-frequency sensors along with the sub-faulting behaviour as observed in high frequency signals recorded close to the source. We investigate the dynamics of sub-fracture failures during the rupture process and growth of the overall fracture from initiation to rupture arrest, the role of asperities, roughness, fluids, the failure mechanisms (shearing versus tensile dominance of behavior), and the conditions under which induced-triggered failures may occur.
Based on our observations, fault activation was related to decreasing frictional resistance on the fault surface due to the presence of fluids. The increasing magnitude for sub-events during fault activation suggests that slip over a larger contact area such as an asperity and that fluid influence was dissipating.
Overall, failure was dominated by a shearing mode of failure, whereas the sub-fracture failures were mixed-mode, that is, more complex than a simple shearing process and included a strong tensile component of failure that evolved in time. However, from this example, it is difficult to ascertain if fault activation was triggered or induced; it appears both modes are plausible.
Wettability Alteration with Brine Composition in High Temperature Carbonate Rocks
Authors: Chandrasekhar Sriram , Sharma Himanshu , Mohanty Kishore K. 
Published: September 2016

Abstract
Injection of brine with tuned composition has been shown to give improved oil recovery from carbonate rocks. Contact angle studies, spontaneous imbibition and core flood experiments have shown that wettability alteration is responsible for this process. Possible mechanisms include mineral dissolution and ion exchange, which have been investigated by zeta-potential measurements and geochemical modeling of both processes. In this study, the core scale manifestation of these mechanisms is evaluated, and a geochemical model is developed for further insight into reaction pathways. Brines of different compositions were injected into carbonate cores with no oil and the effluent was analyzed for ionic composition. Seawater, sulfate-rich seawater, and dilutions of seawater were tested. Two phase oil displacement core floods were performed for the same brine cases to correlate the oil recovery to the geochemistry. A mechanistic model was developed using our in-house reservoir simulator UTCHEM-IPHREEQC for the wettability alteration process. The single phase core floods with all test brines indicate retention of SO42− within the core, seen by a delay in its effluent concentration reaching the injection concentration. Na+, Ca2+, Mg2+ and Cl− ions mostly behave as tracers in the system. In oil displacement core floods, formation brine recovers 40% OOIP on average and seawater recovers an incremental 7% OOIP. Sulfate-rich seawater and dilutions of seawater increase the recovery to 65-80% OOIP in secondary and tertiary modes, requiring more than 5 PVI. SO42− ion delay is not observed in the two phase core floods. Ca2+ concentrations remain high after 5 PVI of diluted seawater, indicating a slow dissolution process in the low salinity floods. The mechanistic model results were in good agreement with the single phase coreflood experiments and oil recovery experiments. The model showed that the reduction in surface concentration of naphthenic acids was responsible for altering the wettability on the injection of modified brines.
Flow of Multicomponent Gases in Carbon-Based Organic Nanopores
Authors: Kazemi Mohammad , Takbiri-Borujeni Ali 
Published: September 2016

Abstract
In the study of transport of gases in shale reservoirs, a special attention should be paid to gas transport in organic nanopores due to their nano-scale pore sizes and adsorption phenomena at the pore surfaces. Most of current studies are focused on the transport of single component fluids, mainly methane. The objective for this work is to investigate transport of multicomponent gases in carbon-based organic pores.
In this study, adsorption and transport of multicomponent gas systems in identical setups of graphite channels with rough surfaces are investigated using non-equilibrium molecular dynamics simulations (NEMD). Simulations are performed for two gas samples with different compositions for channel heights of 2 and 4 nm. For each simulation, the velocity, density, and mass flux profiles are computed. Moreover, the selectivity values of heaviest molecule (hexane) over other gas components are determined. Finally, diffusion coefficients of each gas component are computed and compared.
Based on MD simulation results, most of heavier gas components are adsorbed to the wall. Hexane, which is the heaviest gas component, has a higher tendency to be adsorbed to the channel walls compared to lighter gas components. Therefore, in real systems, most of the heavier components may stay in reservoir in adsorbed state. Furthermore, in contrary to previous studies in which plug-shaped flow profile were observed, parabolic-shaped velocity profile are observed due to presence of rough channel surfaces and heavier gas components. Based on the simulation results, heavier gas components have lower diffusion coefficients compared to lighter components.
This work is one of the few in-depth investigations of the transport of natural gas systems in organic pores. The results in this study can potentially modify the multiscale formalism of fluid flow in shale resources.
Truly Sustainable Building Blocks for Deepwater Field Development: The Need for Strategies Re-Definition in a Persistently Low Oil Price Scenario?
Authors: Beltrami Francesco , Hansen Kevin 
Published: September 2016

Abstract
The abrupt changes that occurred to the oil and gas industry at the end of 2014 and the persisting low oil price scenario appear to challenge the previous perception that the deepwater market was going to successfully continue its remarkable growth. In the light of the new economic scenario, the current deepwater technologies adopted in deepwater field development may be seen as too expensive or not affordable any longer. To survive, the deepwater industry needs to change and to re-think the way projects are carried out. This paper reviews the main ‘building blocks’ for deepwater field development planning, discussing how they are currently used and exploring more affordable, but technically robust, alternatives. The results of this original investigation are discussed and practical solutions are presented.
Operators need to continuously replace the reserves that are being produced. Deepwater blocks may have to be developed, sooner or later, even in a lower oil price scenario, to avoid the operator losing the rights on the same blocks. For these reasons, a discussion on the re-definition of field development strategies is of interest to the deepwater community. Clarifying which are the main building blocks and which is the more sustainable way to employ them in field development will hopefully help the recovery of the deepwater industry. The paper discusses the main technologies and components of a typical deepwater development, including subsea processing, and presents practical conclusions, identifying gaps, proposing alternatives - when desirable, and listing open issues that deserve further attention.
This paper is a contribution to the unavoidable discussion that both international operators (majors and independents) and national oil companies face when it comes to the future development of deepwater fields worldwide. The sustainability of the technical solutions required for such development is a key aspect and needs to be properly addressed. Reflecting on how field development options are presently identified and handled during concept definition and concept selection is now necessary. The re-definition of development strategies appears equally critical with respect to a possibly persisting low oil price scenario.
Design and Implementation of the First CO2-EOR Demonstration Project in Saudi Arabia
Authors: Kokal Sunil , Sanni Modiu , Alhashboul Almohannad 
Published: September 2016

Abstract
Enhanced oil recovery (EOR) using CO2 is an important recovery process that can increase recoverable hydrocarbons and sequester CO2 simultaneously. For light oils, CO2 injection is particularly interesting and is considered a win-win strategy that sequesters CO2 and provides additional oil reserves at the same time.
Saudi Aramco has designed and implemented the first CO2-EOR demonstration project in one of the fields. It is worth mentioning that while Saudi Aramco does not require EOR oil for decades to come, this project is being pursued primarily to demonstrate the feasibility of sequestering CO2 through EOR in the Kingdom and using it as grounds to test new monitoring and surveillance (M&S) techniques. The project consists of two components: the actual EOR project in a small part of a field, and the CO2 capture plant. An overall plan covering laboratory and research studies, reservoir modeling and simulation, monitoring and surveillance, construction of a CO2 capture facility, project implementation and evaluation will be presented for this first demonstration project.
The project uses 40 million standard cubic feet per day (MMscf/d) of CO2 that is being captured and processed from an existing facility and piped about 85 km to the field location. An innovative progressive infill line drive has been implemented to take advantage of the east-west fluxes in the field. This includes a row of four injectors and four producers, and another set of observations wells for monitoring and surveillance. The CO2 is being injected in a water-alternating-gas (WAG) mode. An elaborate monitoring and surveillance program has been established and currently being implemented to evaluate the performance of the project. It includes the deployment of several new technologies including seismic, inter-well tracers, gravity, geochemical sampling and analyses that will be discussed in the paper.
The main objectives of the demonstration project are estimation of sequestered CO2, determination of incremental oil recovery, addressing the risks and uncertainties involved, including migration of CO2 within the reservoir and operational concerns. It is estimated that up to ~40% of the injected CO2 will be sequestered permanently in the reservoir.
Investigation of Methods to Rotate Casing Sections Independent of Surface Rotation
Authors: Fleckenstein W. W. , Eustes A. W. , Yaakob G. H. , Rostad R. D. 
Published: September 2016

Abstract
It has long been recognized that the movement of casing can improve cement jobs and assist in running casing in challenging well trajectories. Both reciprocation and rotation of casing relies upon the use of the rig at the surface to rotate or reciprocate the entire casing string, which may be undesirable for operational or safety considerations. Rotation of casing from the surface may also result in unacceptable stresses on the casing string. This paper presents the results of an investigation into a method to rotate a section of the casing without the use of surface rotation, but instead using a hydraulic device to rotate a specific section of the casing. In many applications, the most critical portion of the casing to achieve a quality cement job and resultant seal in the annulus between the casing and the borehole is the bottom sections of the casing. A method is presented to rotate a section of casing by the use of a hydraulic device placed below the float collar, which rotates a section of casing from the bottom up. This casing section is decoupled from the non-rotating section of the casing by means of a sealed rotation element, allowing only critical section(s) of the casing to be rotated. The placement of the hydraulic device below the float collar allows the device to be drilled up or left encapsulated in cement, for operational efficiency. The casing rotation is imparted hydraulically by the use of a rotary mechanical device that extracts energy from a fluid flow and causes the section of casing to rotate in response to a fluid being pumped through, such as cement, spacers and drilling fluids. Modeling of a variety of hydraulic device configurations and experimental experience with several prototypes using surface tests at low hydraulic horsepower configurations indicate that sections of casing can be rotated hydraulically for various applications. Several different configurations of downhole devices were examined, and were capable of a variety of rotational speeds and torques, depending on the specific application that the casing is rotated for. Multiple devices may be used in tandem to produce more hydraulic horsepower, as needed for a desired application, or to provide rotation at several critical areas.
Prevention of Halite Formation and Deposition in Horizontal Wellbores: A Multi Basin Developmental Study
Authors: Hebert Jeff , Leasure Josh , Saldungaray Pedro , Ceramics Carbo 
Published: September 2016

Abstract
Halite scale is a wide spread problem throughout several basins in the United States. This scale can form in surface equipment, downhole tubulars as well as affecting production. Traditional remediation of halite can be accomplished by dissolving the scale in fresh water as well as recycled water. In most cases the operator must factor in the cost of fresh water, trucking, manpower, anti-scale additives, and disposal of additional produced water. These treatments are often frequent with multiple applications per week.
The approach described in this paper will prevent the formation of halite scale for a given period of time. This is accomplished through the use of a new porous ceramic proppant-based chemical delivery system in which a halite inhibitor is infused. The infused halite inhibitor is encapsulated with a semi-permeable membrane to regulate the elution rate of the inhibitor from the porous proppant carrier. The chemical delivery system is added to the bulk proppant as a small weight percentage of the bulk proppant and is placed in the fracture as normal proppant.
Several wells in the multiple basins for several E&P companies were completed using this new chemical delivery system, which allowed for a significant amount of halite inhibitor to be placed within the proppant pack. As fluids flowed over the proppant pack the halite inhibitor was slowly released. This paper intends to describe the mechanism for which the inhibitor acts, the control release mechanism of the substrate and the engineering behind the placement and volumes of the halite infused proppant. This paper will also discuss the data collected from laboratory modeling and the implementation of these products in fracturing applications. The use of this chemical delivery system will allow these operators to defer remediation, lowering lease operating expenses.
This paper will be useful to all production and completions engineers and technicians operating in an area with halite scale issues. This new chemical delivery system allows for deferred implementation of traditional remediation strategies while extending the most productive time of the wells life. This halite inhibitor delivery system not only improves estimated ultimate recovery but also lowers lease operating expenses.
Calibrated Clay Parameter Improves Continuous Permeability Estimation with LWD Logs in Complex Siliciclastic Reservoirs
Authors: Li Xingli , Lu Yunlong , Zhu Jianmin , Wang Xijie , Li Ting , Zhang Lei 
Published: September 2016

Abstract
For conventional reservoirs, matrix permeability is a crucial petrophysical parameter for completion design and reservoir characterization. However, direct measurement of permeability is difficult to obtain through well logging. Traditionally, continuous permeability is estimated from porosity log using relationships derived from core measurements. This method can result in inaccurate permeability values when there's a poor correlation between porosity and permeability.
It has been shown previously that the kΛ equation can accurately estimate permeability when applied to log data. This equation computes permeability from lithology weight fractions by associating a specific surface area (S0) value with each lithology. In general, S0 for sand and carbonate are well defined and stable. However, the specific surface area for clay (S0clay) depends largely on clay type and can be highly variable from reservoir to reservoir. Since clay has the most significant effect on permeability, the wrong assumption on S0clay will lead to strong bias in the interpretation results.
In modern logging programs, formation pressure tests are commonly included for reservoir characterization. By observing pressure behavior versus time in a pretest, one can directly measure fluid mobility at discrete stations. We can then use the measured fluid mobility to calibrate S0clay and compute a continuous permeability log. Here is the workflow:Zone the well such that the clay is of the same type within the zones.Using a univariate optimization routine, find S0clay the value that minimizes the sum of squared difference between permeability from pressure tests and permeability from well logs within the zone.Use the calibrated S0 for clay to compute a continuous permeability log from quantitative lithology.
In this report, we demonstrate that in a complex sandstone reservoir containing interbedded sand and shale, the variability in permeability is fully captured by the continuous permeability log. The calibrated clay S0 ensures that the interpreted permeability matches measured permeability from pressure tests.