bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probabilistic Reservoir Simulation Workflow for Unconventional Resource Play: Bakken Case Study
Authors: Luo Shanqiang , Wolff Martin , Ciosek Jessica , Rasdi Faisal , Neal Lane , Arulampalam Pathman , Willis Sean 
Published: September 2011

Abstract
It is widely accepted that unconventional resources hold enormous reserve potential. However, complex fluid flow physics and completion/stimulation practices pose a unique challenge in estimating reserves or making long-term production forecast for these unconventional reservoirs, as traditional methods are most often not applicable. This paper proposes the application of a probabilistic reservoir simulation workflow to provide realistic range of production forecasts with successful application in the Bakken unconventional tight oil reservoir. First, geomodels are constructed and ranked. Then, key static and dynamic uncertainty parameters are identified for the subsequent history-matching study (with each of the geomodel realizations) that provides not only production forecast for individual wells but also parameter ranges for experimental design (DoE) for field-level prediction. Then, DoE simulations are conducted to construct proxy equations that are used in Monte-Carlo simulations to generate Low-BTE-High response S-curves for the field-level models. Finally, based on these S-curve results, Low-BTE-High deterministic reservoir simulation models are constructed to generate corresponding long-term production forecast profiles for full-field development and optimization.
Fill-Up Test Process for Unconventional Gas Reservoirs (Case Study)
Authors: Megyery M. 
Published: September 2011

Abstract
Results of hydrocarbon exploration in Hungary indicated that most of the oil and gas accumulations were formed by a vertical migration from the sources of the deeper part of subbasins, which was due to the tectonic activity in contrast with tectonically stable provinces. 950 conventional oil and/or gas reservoirs were explored in this territory. I was a participant of these reservoirs’ well-tests and in the researches of the local unconventional reservoirs (coal bed methane; tight gas; high level radioactive waste geological disposal).
Fill-Up pressure test process, which is a method used for wells with low initial oil and gas production and deep drawdown, was patented. Besides such production conditions, the pressure buildup (PBU) data that were obtained by wellhead shut-in were inadequate for calculating formation parameters. After stopping the production, the Fill-Up process ensured the wells’ complete fluid saturation, thus, further possibility of flowing-in fluid was precluded and pressure buildup data equivalent to bottom hole shut-in were provided. The advantage of the Fill-Up method is that it can be completed at any well constructions; furthermore the fluid transmits the bottom pressure-changes to the surface (this is a kind of surface readout).
During our practice, 121 gas-wells were measured by Fill-Up, 75 of them gave reservoir parameters. After Filling-Up at these wells the pressure started to increase. After Fill-Up, pressure decline was found in 35 wells. Based on our experience, the production of these parts of the reservoirs could not be increased.
The use of the Fill-Up method at unconventional reservoirs will give us reservoir parameters or other information which will improve the planning and implementation of the formation treatment. This way a part of treatments can be omitted.
Downdip versus Updip Gas Injection Evaluation in a Deepwater Development
Authors: Sadikoglu Kasim , McQueen Matt , Sweatman Mark 
Published: September 2011

Abstract
Downdip versus updip gas injection options have been evaluated for a deepwater multi-reservoir development discovered and appraised over the last few years. At the time of the study, the development plan called for gas injection in the Alpha field until gas export to the mainland became available. The name of the field has been changed to preserve confidential data.
The depositional model of the Alpha field envisages stacked turbiditic channel systems meandering from east to west. The field is tilted approximately 30 degrees north-south due to post-deposition tectonic movement. As a result, the apex region of each meandering channel may form attic-traps that can only be swept by a fluid lighter than oil. Whilst downdip gas injection offers the potential of recovering the oil in these attics, it also carries the risk of gas over-running towards updip producers causing excessive gas production.
A study was performed to assess various gas injection scenarios using 2D and 3D reservoir simulation. A simple model utilising a single channel at various dip angles was built prior to any detailed simulation to study fluid movements and demonstrate proof of concept. Fully integrated geological sector and full-field models were then constructed using an object-based modelling technique to assess downdip and updip gas injection options in multiple equiprobable stochastic realisations.
The study concluded that counter to conventional thinking, downdip gas injection both delays gas breakthrough and recovers more oil in this reservoir. These benefits were the result of: Downdip injection scenarios offering greater opportunities for gas solution in the highly undersaturated oil prior to accumulation at the crest;Increased offset between producer and injector.Displacement of trapped oil in tilted-channel attics improving sweep;
Based on the outcome of this study, downdip gas injection was integrated into the development plan. Later developments in the project enabled gas export from first oil, rendering gas injection unnecessary.
An Experimental Investigation of Carbonate Rock Wettability after Stimulation Fluids Invasion
Authors: Saneifar M. , Fahes M. , El Cheikh Ali N. , Zoghbi B. , Hill D. 
Published: September 2011

Abstract
Trapping of spent acid after acidizing job is a major problem in carbonate rocks. Spent acid needs to be fully mobilized and recovered in order to enhance gas production. Wettability of the rocks and capillary forces are the main reason behind fluid trapping in carbonate formations. These forces can be weakened by decreasing surface tension and increasing contact angle. Additives that are injected along with the acid can have an impact on changing the surface tension, contact angle and possibly the wettability of the rocks. Previously, separate studies were conducted on the effect of acid additives on contact angle and surface tension. However, there is still a need to investigate the overall impact of acid additives on these two parameters and wettability on the trapping of spent acid in the carbonate rocks.
In this paper, the full impact of two additives, formic acid and methanol, on trapping and wettability is investigated. Irreducible fluid saturation is compared before and after the exposure of rocks to spent acid. Formic acid decreased irreducible fluid saturation whereas methanol increased irreducible fluid saturation. Spontaneous water imbibition was conducted in each case to ensure that there is no permanent effect on rock wettability as a result of using these additives. It is very important to understand that the effect of various additives on wettability must be studied before any acid job, as their impact on wettability can consequently affect well productivity.
Improved Understanding of CO2/Foam EOR Techniques by Aid of Tracer Technology
Authors: Dugstad Øyvind , Opel Karsten , Fjelde Ingebret 
Published: September 2011

Abstract
Poor macroscopic sweep efficiency can be a problem in CO2-flooding of oil reservoirs. The macroscopic sweep efficiency can be low due to the combination of high mobility ratio, gravity segregation and heterogeneity. By decreasing the mobility of CO2 the macroscopic sweep efficiency can be improved. In the present work the surfactant, alpha olefin sulphonate (AOS), has been used as CO2 foaming agent. Dynamic flooding experiments have been carried out at realistic reservoir conditions to study the relative transport of water, CO2 and surfactant when foam is generated in the porous network. The surfactant has been labeled with the radioactive sulfur isotope 35S. The water has been labeled with the radioactive hydrogen isotope tritium (3H) and the CO2 has been labeled with the 14C isotope.
It is shown that the flow of the individual phases in a CO2-foam flooding can be monitored by using of tracer technology. Variations in the flow rates of surfactant solution and CO2 can be clearly detected, and the accessible pore volume can also be determined. AOS products contain different chemical structures. In the study, the main AOS components have been chemically separated prior to injection on the porous column. The transport of the individual components was shown to be different. In the reservoir, chromatographic separation of the AOS components may change the efficiency of the foam process.
The study has shown that use of tracer technology can be a powerful tool in study of transport mechanisms in CO2-foam flooding.
Gas Tracer Transport - Correct Formulation and Fast Post-Processing Simulation Technique.
Authors: Huseby Olaf , Sagen Jan , Dugstad Øyvind 
Published: September 2011

Abstract
This paper describes a fast post-processing method for simulating gas tracer transport. The partitioning between phases is described by a convenient and correct formulation. Gas tracers (e.g. per-fluorinated or radio-labelled hydrocarbons) can be used to trace injection gas during secondary recovery, CO2-injection for CCS or EOR etc. Laboratory experiments show that commonly applied reservoir simulation methods for gas tracer transport should be improved. This paper highlights the effect of gas tracer partitioning between phases and presents a formulation that can be used in practical reservoir simulations. A fast post-processing tracer simulation technique is introduced to solve the gas tracer transport in real-field reservoir cases. The formulation of the solution exploits the fundamental assumption that tracers do not affect the phase transport. The partitioning of the tracer components is solved fully coupled with the tracer transport. The post-processing is based on previously solved reservoir simulation runs and gives significant savings in CPU-time. Using laboratory results for several gas tracers, we observe that models based on commonly applied tracer formulations, are unable to correctly handle the tracer partitioning between the gaseous and oleic phases, and that the formulation presented here resolves that problem. Using real-field reservoir simulation cases, we demonstrate the practical improvement achieved. Our main conclusion is that a correct description of gas tracer phase partitioning is important to enhance predictions from gas tracer tests. The paper contributes to improved and rapid gas tracer simulation, important for correct interpretation of gas tracer results from inter-well tracer tests in petroleum reservoirs. The formulation of the equation and the simulation techniques described is also valid for other applications, such as water tracers, CO2-sequestration, non-aqueous phase liquids etc.
Sweep Efficiency in CO2 Foam Simulations With Oil
Authors: Liu M. K. , Andrianov A. I. , Rossen W. R. 
Published: September 2011

Abstract
We simulate gravity segregation and sweep in foam EOR in miscible and immiscible displacements of oil to investigate the effect of oil on foam sweep and the usefulness of simple models designed to predict the extent of gravity override with foam. Comparison of simulation with analytical models highlights limitations of both approaches. In 1D simulations with fine grids, both first-contact and multicontact miscible displacements fit the fractional-flow model for miscible foam floods (Ashoori et al., 2010). In simulations of either sort of displacement, the "critical oil saturation" for foam stability is irrelevant because "gas" and "oil" never co-exist at the same location. Hydrocarbon kills foam abruptly at the point where the simulator changes the name of the nonaqueous phase from "gas" to "oil."
In 2D homogeneous reservoirs, the model of gravity segregation of Stone (1982) and Jenkins (1984) must adapt to an inhomogeneous mixed zone for two reasons. First, if pressure varies greatly in the mixed zone, then foam mobility varies there, because in many foam models foam mobility is a function of gas viscosity. In reality, foam mobility is not sensitive to viscosity within bubbles. Second, residual oil saturation can vary in the mixed zone. For miscible displacements Stone and Jenkins' equations work well if one takes gas properties at the middle of the mixed zone. For immiscible displacements, the variation of residual oil saturation in the mixed zone can make the distance to segregation of gas shorter or longer than predicted by Stone and Jenkins depending on whether residual oil kills foam or not.
"Modified SWAG" injection (injecting water simultaneously above gas) gave from 70 to 130% greater sweep than co-injection at the same injection rates in our simulations.
Ni-Fe Nanoparticles: An Innovative Approach for Recovery of Hydrates
Authors: Bhatia Kutbuddin , Chacko Levin 
Published: September 2011

Abstract
Gas hydrate is a crystalline solid consisting of gas molecules, each surrounded by a cage of water molecules. They produce 160 times their volume of methane which is an infinite source of energy waiting to be tapped, but the technology to recover these hydrates is at its infancy. Recovery of gas from hydrates requires the dissociation of gas hydrates which can be accomplished in at least three ways: thermal recovery, depressurization or by chemical inhibition. But, the problems associated are: Most chemical additives (salt, methanol, and glycol) cause pipe and equipment corrosion, ecological problems.Preheated gas or liquid transportation down to hydrate zone is accompanied by extensive heat loss.Microwave or electromagnetic method also requires vast energy transfer to decomposition zone and is inefficient.
This paper proposes the injection of air-suspended self heating Ni-Fe nanoparticles (50 nm) in the hydrate formation through horizontal well. These particles will penetrate deep into the class I, II and H hydrate reservoir by passing through the cavities (86–95 nm).
The self heating of particles in a magnetic field is caused by hysteresis loss and relaxation losses. These particles cause temperature rise up to 42 °C in formation leading to disturbance in thermodynamic equilibrium and causing the water cage to decompose and release methane. In this technique, the pressure of the fluids in contact with hydrate is lowered, pushing the hydrate out of its stability region and leading to its decomposition.
It has been discovered that the less expensive, readily available Eggwhite (Ovalbumin) can catalyze the reaction which results in large scale formation of these nanoparticles. The main advantage of this technique is the very low dosage requirements (small quantity required for 1m3 of Hydrate decomposition). Moreover, the nanoparticles used are non-poisonous, environment friendly.
Integration Of Seismic Lithology Data In The Reservoir Model
Authors: Calabrese M. , Pirera F. , Rossi M. , Scaglioni P. , Tosoratti F. 
Published: September 2011

Abstract
The Marulk field is a gas condensate accumulation located in PL122 in the Norwegian Sea. The field was discovered in 1992: hydrocarbons were encountered in Lysing and Lange formations. The field is operated by EniNorge and it will be put on production with a direct tie-in to the existing Norne FPSO.
An update of the reservoir model was based on a new acquired high-quality Q-marine seismic volume, and reservoir properties were distributed using the geophysical attributes: a successful elastic seismic inversion was performed and used as input to the lithology classification study. This supervised Bayesian classification made use of multivariate Probability Density Functions (PDFs) of selected inverted attributes for each litho-class as a-priori information to constrain the classification. Litho-class selection started by analyzing raw and interpreted logs at well locations and petrofacies obtained by means of an integrated petrophysical model. Eventually a new class subdivision was obtained, closely reflecting not only the well data but also the actual geophysical response.
This approach resulted in a quantitative estimate of the uncertainty in lithology prediction: significant maps were extracted from Probability volumes of geophysically consistent lithology classes. The obtained probability maps allowed driving the facies distribution in the 3D grid improving the reservoir architecture knowledge and providing a valuable link among seismic data, logs, petrofacies and sedimentological model.
Ultrasonic Peening, a Solution for Fatigue Cracking on Offshore Installations
Authors: Hedmar M.. , Martinez L.. 
Published: September 2011

Abstract
By using Ultrasonic Peening the service-life of an offshore installation can be extended.
Every floating installation will have weak spots in its structure, this is almost enivatble. We call these weak areas "fatigue hot-spots". In practice the fatigue hot-spots are the locations were the first cracks start to initiate in the structure; in affect these cracks will threaten the structural integrity of the structure. Ultrasonic peening is a pro-active solution to prevent fatigue cracks to initiate at these locations. The method is a practical and efficient solution for structural integrity challenges related to fatigue cracking. It can extend the service life of high stressed weld joints in an offshore platform by four times1 if the weld quality is adequate. Even though Ultrasonic Peening is a very efficient way to strengthen the integrity of offshore installation, the method will always be dependant on the existing weld-quality. As ultrasonic peening is a post weld treatment it can not magically transform a bad weld into a good weld, it can only enhance a good weld to an even better weld. Ocassionally Ultrasonic Peening Technicians comes across fatigue hot-spots with bad weld quality. In order to be able to estimate the benefit of Ultrasonic Peening even if the weld quality is inadequate, a couple of fatigue trails were designed to investigate this further.
Two seperate batches of F Specimens were manufactured.
-As- welded; used for reference purpose
-As welded + UP treated; Specimens were first put under fatigue cycles until ½ of the predicted fatigue life had been consumed, the specimens were then treated with the LETS Global Ultrasonic Peening Procedure, after these two steps the specimens were put back on the fatigue trail until failure.
It was made sure that all the specimens had a relatively bad weld quality. For example the weld toe angle was too high and the weld toe was filled with irragularities.
The results show that Ultrasonic peening doubles the fatigue life of a welded attachment eventhough; the weld quality is poor and even if the welded attachments have already consumed half of its fatigue life. This corresponds with American Bureau of Shipping’s official guidelines2.
This document focuses on the benefit of Ultrasonic peening on offshore installations which have already consumed a big part of their service life and have locations with bad weld quality. Since operators tend to focus on life extension of offshore installations beyond the original desgined service life at a relatively late stage, ultrasonic peening is often used when the welded attachments have used half or more of their intended service life.
Extended Draft Semisubmersible
Authors: Sablok Anil , Edelson David , Kim Jang , Luo Mike 
Published: September 2011

Abstract
An Extendable Draft Semi-submersible (EDS) is a low-motion floating production system concept focused on flexibility and low cost. An Extendable Draft Semi-Submersible (EDS) can support full drilling and production facilities that can be prepared for deployment at a dockside facility with limited water depth. The EDS combines the favorable features of deep-draft Semi-submersibles, Truss Spars and other reduced-heave floaters, making its in-place motions superior to shallower-draft floaters for supporting dry-tree risers and SCRs.
EDS is a self-installing design, which delivers and deploys a fully operational system without the aid of crane vessels. The EDS structure consists of a floatable deck, stabilizing columns and heave plate/pontoon connected to the bottom of the columns. The barge-type deck is designed to float the entire structure, including topsides, to the near shore site. Upon arrival, the columns and heave plate/pontoon is lowered down using strand jacks either in a single or dual direction mode and locked into the deck to the locking draft. The use of strand jacks allows the lowering operation to be performed in a higher sea state than normally used for offshore installation thereby increasing the operability. The deck is then raised to the operating elevation by de-ballasting the columns after pawls are engaged between deck and columns for rigid connection between them. The pawl connection between columns and the deck is reversible and the columns can be raised above the deck to enable the platform to be towed to a new location for redeployment or brought to quayside.
An alternative to the self-installing design is installing the topsides by a floatover technique, similar to what has been done for several semi-submersibles in Brazil.
The EDS motions are suitable for Dry Tree application and SCRs in different areas around the world including areas with severe storm environment like Gulf of Mexico, Weastern Australia, etc. The concept provides flexibility in constructing the EDS that facilitates a high level of local content in most areas of the world.
This paper describes the features of the EDS platform along with the fabrication and deployment offshore.