bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Extension of the Fatigue Design Life of Fixed Oil Platforms in Brownfields by Easy Model Refinements
Authors: Fernandes G. C. , Da Silva R. P. , Ribeiro M. V. , Siqueira L. A. 
Published: October 2015

The recent decline in oil price directly affects the investment plans of the oil and gas industry. Due to the slowdown in this sector the allocation of resources in brownfields stands out in the current conjuncture. In today's economically challenging environment, the extension of the platform fatigue design life has become critically important from an economic perspective and because in many cases, platform design life has already been exceeded. An evaluation study was developed targeting the extension of platform design life through the refinement of fatigue analyses.
This work focuses in the improvement of environmental data, like increase of number of wave heading and wave spreading with a better representation of the platform boundary conditions by the implementation of super elements to simulate the soil-structure interaction and using the spectral approach for the fatigue evaluation. These issues were treated individually in order to observe the influence of each one in the analysis results of a representative sample of fixed platforms installed in Brazil.
After the analyses were completed, a comparative study between the results of the refinement performed and the original calculation condition was performed. The results show the level of improvement obtained in the increase of the fatigue design life for the items taken under consideration and their relevance, individually and combined.
It could be concluded that readily achievable improvements in fatigue analysis methodology coupled with refined information, which may already be available, can result in a significant increase in the fatigue design life without the need for high cost inspections. Additionally, through the experience developed in structural re-analysis of existing fixed platforms, other issues like the consideration of local joint flexibility, nonlinear analysis approaches and reliability analysis can also be considered in future jobs to further enhance platform life.
Water Alternating CO2 Injection Process - Does Modifying the Salinity of Injected Brine Improve Oil Recovery?
Authors: Ramanathan R. , Shehata A. M. , Nasr-El-Din H. A. 
Published: October 2015

In the recent past, IOR/EOR technologies have been modified to include the effects of salinity of injected brine on oil recovery. Water Alternating Gas (WAG) is one such tertiary oil recovery process in the field. It greatly improves the synergy of various individual mechanisms underlining EOR processes, such as ion exchange, wettability alteration, and mobility control. This process has matured over the years, but the alteration of the salinity of injected brine during WAG has not been experimented extensively. This paper investigates the effect of injected brine salinity during water-alternating-CO2 injection and compares its performance with standalone brine injection, using 20 in. length outcrop Grey Berea sandstone cores. The water alternating CO2 process was done under immiscible conditions. It also studies the effect of aging on the oil recovery during waterflooding process.In the present work, six coreflood experiments were performed: four experiments before aging the cores and two experiments after aging the cores. All of the experiments were done at 149°F. The evaluation of oil recovery and pressure drop were done for each coreflood. The effect of salinity on the rock wettability during waterflooding and water alternating CO2 processes was studied using axisymmetric contact angle measurements.The effect of salinity on the waterflooding process as well as water alternating CO2 injection process was observed through the coreflood experiments. Low-salinity brine gave the highest recovery during the waterflooding process in aged cores, and seawater brine gave the highest recovery during water alternating CO2 injection process. Wettability alteration towards a more water-wet state was the cause of improved oil recovery by low-salinity brine during the waterflooding process. The lower solubility of CO2 in seawater brine compared to the solubility of CO2 in low-salinity brine was the reason for the higher oil recovery by seawater brine during water alternating CO2 injection process. Fines migration was observed during low-salinity brine alternating CO2 injection process. Aging played an important role in the recovery of oil during the waterflooding process. There was greater oil recovery in aged cores compared to unaged cores. The salinity of brine affected the contact angle measurements of the Grey Berea sandstone rock. The rock was strongly water-wet in the presence of low-salinity brine. Seawater brine made the rock more oil-wet due to the ion binding nature of the divalent ions in seawater brine. The aging of the cores increased the contact angle of the rock, thereby making the rock more oil-wet.
Managing Risk and Cost Using Autonomous Marine Vehicles
Authors: Tichatschke C. , Pai S. 
Published: October 2015

Oil companies are turning to new technology to find alternatives to obtain offshore datasets. A remotely piloted, renewably powered, autonomous marine vehicle (AMV), is a prime example of this new and innovative approach to offshore operations. Vital data can now be sent straight to the client's desk using the vehicle and satellite based communications. The vehicle by virtue of its low profile and flexibility on maneuvering around obstructions can be placed as close to an obstruction as possible, reducing the risk typically involved in an operation of this nature. Furthermore, its autonomous nature makes it the ideal vehicle for METOC real-time data acquisition and transmission in the presence of harsh weather and oceanic conditions. In the case of marine seismic acquisitions, the valuable intelligence gained concerning the surface currents behavior significantly helps the party chief and his/her team to ensure they run the operation efficiently and safely (stability of the streamer spread). This paper will describe and provide data on how this vehicle has been used in the mode of data delivery for optimizing marine seismic navigation decisions in South America.
A major operator used the AMV equipped with Acoustic Doppler Current Profilers (ADCPs) to adapt a seismic survey offshore Uruguay to the local METOC conditions. The AMV was deployed to measure current strength, and provided real-time current data via satellite as the survey was underway. This information helped the party chief prioritize areas of acquisition in order to avoid entangling of the streamer and reduce the amount of feathering.
This operation was done in a cost-effective manner, and the vehicle replaced systems usually mounted on chase vessels, which were deployed for other important navigational challenges on the operation. The streamer survey was optimized without compromising results due to the vehicle's ability to hold station in the presence of currents.
By utilizing the AMV the operator was able to accurately estimate the uncertainties of a seismic survey in a remote location where data is not readily available. The AMV's persistence and endurance during the mission demonstrated its overall capabilities, it was able to do work previously done by manned vessels that deployed the moored ocean monitoring buoy, and it provided a significant reduction in capital and operation costs. This two part system is deployed as an integrated system and has the flexibility and adaptability to be deployed in a variety of marine areas to monitor meteorological and oceanographic events on, above or below the surface of the ocean. This is a novel concept for the exploration and production industry particularly as companies go into deeper waters that demand higher operating costs. To date 9 of the 26 successful completed operations for various operators have been in support of seismic surveys.
Wellbore Stability Model for Standalone Liner Completed Wells in Carbonate Reservoirs Subjected to Acidizing Jobs – II. Wellbore Stability Simulator
Authors: Santos E. S. Raggio , Ferreira F. H. 
Published: October 2015

Mechanical stability analyses are mandatory to identify suitable candidates for openhole completions. These analyses should comprehend the effects of production drawdown and reservoir depletion state anticipated by the production plan. The understanding and modeling of the physico-chemical interactions between rock and flown fluids and their impacts on the rock mechanical properties have been presented in a companion paper.
This paper introduces the three methodologies intended for the wellbore stability analyses, namely the i) elastic analytical; the ii) empirical solids production and the iii) 2D elastoplastic finite element simulator (FE) and describes the reasons two of them have failed to incorporate the dissolution-induced rock weakening effects on the wellbore stability. The resulting numerical model has been implemented as a standalone specialist 2D FE Simulator. The simulator provides the well design engineers a user-friendly interface upon which they can evaluate the effects of the wellbore and reservoir pressure changes, as well as the aforementioned rock weakening effects from an acidizing job, on the wellbore stability.
The mechanical wellbore response presented by the simulator elucidates how the stress and strain patterns change after an acid well stimulation job. Wellbores under virgin rock conditions tend to fail by localized plastified zones, also referred to as breakouts, whereas wells subjected to acidizing jobs present extensive straining due to rock weakening. The boundaries of the acidized zone encloses a much less rigid rock prone to deform and compact. On one side this compliant zone provides a gradual shear distribution along the well radius inside the formation and mechanical confinement to the surrounding intact rock and therefore helps this rock in supporting the stresses as if the wellbore were much larger. However, on the other side this significant weakened rock volume poses uncertainties about its own stability or solids production risks. The installation of a perforated or slotted liner/casing acting as a bearing element tends to hold this compliant material back and accounts for the material uncertainties and lack of model representativeness in terms of eventual preferential dissolution patterns.
The unprecedented results presented by the developed simulator are assisting the company on the standalone completion decisions and increasing the robustness of well completion designs, therefore assuring the perennity of the CAPEX.
Fluid Conditioning Technology Reduces Days to Target Depth
Authors: Woolums J. , Herrington D. , Coit A. , Sherman J. , Scott E. , Szutiak G. 
Published: October 2015

Drilling in hot-hole applications results in additional time and care spent to ensure the integrity of temperature sensitive downhole tools. Rotary steerable systems, monitoring while drilling equipment, mud motors, drilling jars, and electronic sensor packages measuring vibration, loads, temperature, and pressure all have temperature limitations that, when met, require drilling ahead to halt so that the fluid system can be cooled down sufficiently enough to prevent damage to these tools. Conventional approaches such as circulating to cool and evaporative cooling systems are slow and costly. This paper will detail a solution that is capable of extending the running life of these temperature sensitive tools while reducing the overall cost of the well.
An innovative technology is now available to facilitate the rapid cooling of drilling fluids. The design departs from the nonproductive time spent simply circulating to cool and surpasses the economic capabilities of evaporative cooling systems. This closedloop system has been proven on multiple wells with a variety of configurations and operational parameters to confirm the nature of the system's performance abilities. Downhole tool life was monitored and reliability data gathered to show the improved functional life of these components relative to the performance of the fluid conditioning system.
Performance testing proved directly that run life of electronics can be increased by a factor as high as 43%. This extended run life resulted in reduced trips for changing out tools and in turn improved the overall drilling rate. The reduction in drilling fluid temperatures of up to 45 °F (at surface) and 21 °F at bottomhole in a single pass allowed a reduction in nonproductive time spent circulating to cool of more than a full day.
This paper focuses on the mud chiller performance data and for the overall operations on multiple wells drilled as part of a case study in hot-hole applications. Data presented in this paper will show that the system has the ability to shorten time to depth and reduce the overall cost of drilling operations.
All Data Becomes Big When You Fail To Learn From It
Authors: Snøtun H. , Mathisen P. 
Published: October 2015

Learning is defined as a permanent change in behavior, but in what way have experiences from previous projects influenced the way we plan and execute drilling operations? There is an abundance of data in the oil and gas industry, but this sharp increase in data has not necessarily translated into greater knowledge and insight. The shear waste of time, cost, effort and talent is astounding, from the engineer meticulously reporting the lessons learned during the lifetime of the project, the man-hours spent looking for the correct file, the effort used to be able to compare data from several sources to create recommendations for projects. This process is repeated across projects, companies, regions and disciplines costing millions, but the result often fails to make an impact in planning of the next project.
We have identified several barriers for efficient use of experiences in planning. One such barrier is that the information is not easily accessible, but it is dispersed on a plethora of formats, files, and physical locations, which means that the engineer spends more time gathering the information than actually analyzing it. Another such issue is the data is not easily comparable across wells, fields, and companies, due to differences in reporting, units of measure or drilling parameters. Due to the time-constraints of a project planning phase one might often end up comparing the accessible wells, rather than the relevant wells. A third barrier is that the context of the experience is often lacking, which means that the engineer knows the what was done, but often lacks the tacit knowledge about why the situation arose, like which drilling parameters were used, which formation was drilled through and what bit was used. The sharp increase of data also means that size of the haystack increases, in some estimates less than one 1% of the data captured is analyzed. This makes it harder to find the correct piece of the puzzle, because the engineer not only have to decide what information to use, but also what to ignore.
We will show, using examples from some of Norway’s leading oil companies, how you can overcome these obstacles by focusing on standardization, visualization and collaboration which makes it possible to compare lessons, wellbores and logs across projects. In the past, in the land of the blind, the one-eyed man was king. The future, however belongs to those who can create knowledge out of data.
Design Procedure for Cementing Intercalated Salt Zones
Authors: Jandhyala S. R. K. , Ravi K. , Anjos J. 
Published: October 2015

Abstract
Wells often require being drilled through and cemented across salt formations. In many parts of the world, salt sections consist of multiple salt types. These include Halite, Carnallite and Tachyhydrite. The last two salt types could move one hundred times faster than Halite and are chemically reactive. Typically, Carnallite and Tachyhydrite occur as streaks inserted between Halite. In these cases, cement sheath should withstand salt creep loading. Creep load is primarily compressive in cases of single salt types. For intercalated salts, varying creep rates can result in tensile loads, particularly at salt-salt junctions. Presalt exploration in offshore Brazil is an apt example displaying this behavior. In such a scenario, the cement sheath along a longitudinal well section should be analyzed for both tensile and compressive responses. It is well known that tensile strength of conventional cement systems is low, hence there is the need for detailed analysis and action to prevent damage to cement sheath.
This work demonstrates cement design procedures by evaluating cement sheath mechanical integrity in intercalated salts. A typical presalt Brazilian well with different lengths of Tachyhydrite, Halite, and Anhydrite sections is used as an example in this work. A creep model for these salts is validated with data from triaxial creep testing. Responses of two cement systems, which are cured and tested, are compared. The analysis accounts for classical well loads during drilling and production etc., along with salt creep loading.
This analysis shows that intercalated salts subject cement sheath to a series of tensile and compressive loads whose magnitude depends on the size and relative position of different salts. The salt-salt interface effects dominated the general tenet of increasing creep rate with increasing depth.
This kind of detailed design procedure representing intercalated salt zones is the first of its kind known to the authors. Results from this analysis help fortify the importance of considering salt layering patterns during cement design for long term mechanical integrity. The design procedure discussed and presented in this study should help the industry design cement systems to withstand loads across single and intercalated salt zones and maintain well integrity.
Cementing in Front of Saline Zone and Carbonate Reservoir with Presence of CO2
Authors: Gregatti A. , Carvalho G. , Piedade T. , Campos G. 
Published: October 2015

Abstract
To optimize drilling efficiency, some presalt wells in the Santos basin, Brazil, had their project modified to a configuration in which the entire well is drilled, cased, and cemented in only three phases, in contrast to the usual four phases, thus saving approximately 12 to 15% on the total drilling time. The saline and production zones are cased and cemented in the same phase, requiring a cement slurry design that minimizes salt dissolution and, at the same time, has specific properties for production zone isolation.
The quality of this cement job is key for the success of the project, given that poor cementation could lead to direct exposure of the wellhead to the reservoir fluids, making the three-phases project unviable due to associated risks. It is important, then, to understand and control all aspects that can influence the cement job success.
The presalt reservoir is formed by carbonate rocks that present a variable ratio of gases such as CO2 and H2S. To avoid future risk of gas migration through the cement sheath, the slurry used in the cementing operation must be formulated with gas-migration-control additives to reduce cement matrix permeability.
The salt section is composed of layers of different salt types, with the tachyhydrite and carnallite the most soluble. The results of research conducted with salt rock cores from this basin indicated that the best salt concentration added to the cement slurry, to avoid salt dissolution, is either 15 to 20% sodium chloride or 3 to 5% potassium chloride. It is well known that the addition of salt to cement slurry impairs the slurry properties, especially free fluid and compressive strength, two important parameters to determine a successful cement evaluation. Several laboratory tests were performed until the ideal formulation was defined. The spacers were also optimized to promote superior mud removal. Cementing techniques and best practices such as effective casing centralization, mud removal, losses mitigation, and slurry density control are imperative to ensure job objectives are achieved.
To the time this paper has been written, four wells had been successfully drilled and cemented using the new configuration. Fluids design and flawless execution of the job provided an excellent cement logging evaluation, proving that it is possible to enhance the well construction to save rig time and, consequently, lower the well costs.
New Approach on Drilling Fluids Technology to Improve Drilling Performance
Authors: Lomba R. , Cardoso W. F. , de Sá C. H. M. , D’Almeida A. R. 
Published: October 2015

Abstract
The use of a high quality mud is an essential requirement to guarantee a successful drilling operation. The drilling industry aims to build wells at low costs and as fast as possible. Among other drilling problems, an adequately formulated drilling fluid will prevent wellbore instability while contributing to generate an in gauge borehole. Usually, one of the desired properties of a drilling mud is the least as possible interaction with the drilled formation. On the other hand, the idea of a chemically active fluid that would react with the rock to help improving drilling performance is very welcome. This kind of fluid should not only mitigate drilling problems but also contribute for the improvement of the overall process. The work presents the advances in drilling fluid technology to overcome the challenges that have arisen with the discovery of Pre Salt offshore Brazil, specially the drilling of long salt section containing highly soluble salt layers and the low penetration rates in hard carbonate rocks. An extensive theoretical and experimental work was carried out to assist drilling fluid design in this drilling scenario. A special fluid formulation developed to interact with carbonate rocks and increase penetration rate is presented. Although some important issues have yet to be addressed, the preliminary results show a good potential for the new technology.