bluuebunny/crossref_metadata_2025 huggingface dataset:
Restriction Diagram: Realibility Study of Drilling Ships with Dynamic Positioning System
Authors: Oshiro Anderson Takehiro , Mendes Renato Fernando , Diederichs Gustavo Rocha , Vieira Dalisson Santos , Do Amaral Acacio Sarnaglia
Published: October 2019

The Restriction Diagram is a tool that delimits the minimum distance between a dynamic positioning (DP) drilling rig and surface or subsea obstacles (Platforms, anchor lines, subsea equipment) for safe operation. These diagrams are used for risk analysis and well operations restricting the operation of some rigs in some locations or avoiding very large drilling operations next to each other. They are also used as one of the parameters to determine the best position of the platform in relation to the wells, impacting any subsea layout of a new field development. The analysis of restriction diagrams are essential for risk assessment involving drilling rigs. It is important to improve the quality and robustness of the methodology presented due to safety distances. This proposal of the new model of the Restriction Diagram aims to support the risk analysis of Drilling Rigs operations including the probability of drilling rigs failure, recovery times and hydrodynamic probabilistic modeling. There is integration between all the parameters involved in the process and the propagation of its uncertainties.

The reliability analysis of the dynamic positioning drilling rigs used an extensive database of incident logs, from which was extracted the occurrences of total loss of propulsive capacity of the drilling rigs that resulted in a drift-off. It was considered the operating time and failures that have occurred since 2010, as well as the drilling rig recovery time. The drift-off analysis are represented by means of hydrodynamic modeling coupled to a probabilistic simulator. This risk-based analysis from reliability and environmental conditions will give the chance of collision with obstacles for drilling operations or well intervention.

This paper presents a risk assessment approach according to the new emphases that are beginning to be considered by regulatory authorities such as the Petroleum Safety Authority (PSA) in Norway, considering the integration between decision processes and uncertainty analysis.
Human Factors and Resilience Engineering Program for Safety Culture Enhancement
Authors: Vaz Juliana Casaccia , Touma Silvia Lima , Frota Lucas Costa , Henriqson Eder , De Almeida Paola Cardoso , Garotti Luciano Do Valle , Wambersie Olivier Edward Marie Agnes
Published: October 2019

Safety culture enhancement is currently the most studied approach for HSE performance improvements in the oil and gas industry. However, the conception and implementation of a correspondent program or action plan is still a challenge. This study presents the structure, analysis and results of a human factors and resilience engineering study conducted by Libra Joint Venture and PUCRS. The objective is to build a human factors program focusing on safety culture enhancement in offshore drilling and FPSO operations.

Oil and gas offshore operations can be considered complex social-technical systems with multiple tight-coupling interactions. For this reason, the study’s approach was multidisciplinary, involving professionals from areas of Resilience Engineering, Knowledge Engineering, Knowledge Management, Sociology, Social Service and Environment. The research project consisted of data collection, data analysis and recommendations proposition, validation and prioritization. Tools and methodologies used include interviews, biographic narratives, focus group, workshops, observation, questionnaires and Functional Resonance Analysis Method (FRAM), a systemic analysis methodology widely used in Aviation Industry, to model work as done. A great part of these tools were applied onboard a drillship and a FPSO, both currently operating in the Pre-Salt Area, in Santos Basin.

As the main results, this work provides important field observations and oil and gas industry prioritized recommendations for conceiving a Human Factors Program for offshore operations, with the aim of increasing safety and resilience of the system, which ultimately will reduce risk exposure and avoid accidents.
Decommissioning of Subsea Facilities in Brazil
Authors: Rebello Armando
Published: October 2019

Brazil is entering the age of decommissioning, with aging offshore fields that have been in operation for more than 25 years.

Brazil has migrated from an operator’s monopolistic environment (with the state owned oil company, Petrobras) to a new reality in which many companies, national and international operate in Brazilian waters. As part of this new reality, Brazil has established government organizations whose aim is to coordinate the exploitation of Brazil’s natural resources with the intent of optimizing activities while protecting the environment in an ever increasingly complex eco-system management.

Traditionally, offshore projects follow basic phases such as conceptual, front end engineering and design (FEED), detail design, construction and commissioning. Cost allocation and schedules for these phases are all associated with production estimates and return on investment estimates.

In many instances, internationally, planning for decommissioning has been deferred to an unforeseen future. Finally that far off horizon has become a reality, and domestic and foreign operators in Brazil are going through a new decommissioning awareness phase.

It is the author’s opinion that operators wish to comply with a well-defined frame of Brazilian and international regulations. In general, this paper aims at examining the existing regulatory environment and make recommendations on a path forward for:Clear-cut requirements so that the permitting process flows with a minimized review cycle;A clear set of rules, defining what abandonment options exist (e.g. complete removal vs. partial removal, on-site abandonment rules for topsides and subsea infrastructure);A clear set of rules defining fines and sanctions for environmental violations

The objectives of this paper are to 1) Gather basic information on the current status of the Brazilian Rules and Regulations, 2) Help non-government entities work together to accomplish the goals set forth by Brazilian lawmakers and officials, and 3) Develop a roadmap for convergence of the environmental agency and project stakeholders. Laws, rules and regulations, and international treaties of which Brazil is signatory are part of this environment.
Improving Emergency Response with Better and Faster Remote Monitoring
Authors: Neri Philip , Philo Ross
Published: October 2019

Offshore drilling is reaching for targets further from shore, at greater depths and in more hazardous geological settings such as in proximity to salt. All these factors heighten the risk of poorly managed mishaps evolving into a major emergency. Onshore monitoring centers observe numerous data feeds from the rig, analyzing the information for indicators of potentially dangerous situations. Such centers provide a broad cross-section of expertise to assist in understanding a problem and suggesting remedies. As MWD / LWD took hold in the 1990s, automatic data transfer protocols were used to interrogate servers on the rig and collect data waiting to be transmitted. This would deliver bursts of data 10 to 15 seconds after being acquired on the rig. To offer proper support in emergency situations, data needed to be lag-free. More data channels were needed to get a full picture. A complete re-think of the process to move data from rig to shore was needed. A new standard was developed and published that addressed the specific needs for 2-way data connections for offshore oil & gas, supporting streaming with 1-second lag times, and using one tenth of the bandwidth. This was achieved by defining a compact binary transfer with practically no overhead in the transmission process. A full-scale test was conducted to compare legacy data transmittal processes with the new standard, running both systems in parallel from the same drilling rig to the same onshore facility. The test confirmed the expected 10 to 15 second lag to retrieve data using the legacy approach. The new protocol delivered constant data flows with a lag time as little as 1 to 1.2 seconds after being acquired on the rig. Staff monitoring the data onshore could discuss observations contemporaneously with the rig crew since both were looking at the same data at the same time. In the event of a developing emergency affecting a deep-water drilling operation, the ability to share critical data readings in true real time among a broad constituency of shore-based actors together with the rig crew dramatically improves the ability to reach a fact-based conclusion among all parties in a timely manner. The standard transfer protocol will continue to evolve to better serve the needs of drillers and operators, and their effective management of emergencies.
Leakage Through Micro-Annulus Geometries Incorporating Pressure-Driven Elastic Deformation
Authors: Beltrán-Jiménez Katherine , Skadsem Hans Joakim , Gardner Dave , Kragset Steinar , Lourenco de Souza Marcelo Igor
Published: October 2019

The cement between the casings and formation is a critical barrier element for ensuring zonal isolation. Shrinkage during curing and mechanical or thermal loads applied during production can compromise the cement and result in fluid migration paths such as micro-annuli. The fluid pressure inside the micro-annulus will cause elastic deformation of the channel walls. This deformation should be accounted for when developing methodologies for interpreting micro-annulus fluid leakage experiments and the application to real well conditions. Full-size test sections have been constructed with known cement defects and leakage properties to investigate barrier verification technologies. A micro-annulus test cell, instrumented with strain and pressure gauges, has been leakage tested. Leakage rates have been correlated to the micro-annulus size using a model coupling micro-annulus pressure to radial deformation of the cement and casing. The semi-analytical model and the predictions are compared to the experimental data. Within the regime of linear elasticity, the radial deformation of the cell wall is proportional to the pressure in the micro-annulus. During leakage testing, the pressure-driven radial deformation of the cell materials is coupled to the variation of the liquid friction pressure gradient along the axial length of the micro-annulus. The pressure gradient is greatest at the outlet of the micro-annulus. The models presented have been used to improve the interpretation of fluid flow during micro-annulus leakage experiments. An improved understanding of fluid leakage mechanisms through micro-annuli can be applied to field cases such as the interpretation and choice of treatment for sustained casing pressure build-up.
Real-Time Simulation and Motion-Planning for Riser-Based Drilling and Equipment Positioning
Authors: Bizzi Arthur Augusto Coutinho , Fortaleza Eugênio Libório , Yamamoto Márcio
Published: October 2019

A new analytical approach is applied to the riser's equations of motion, aimed at the real-time processing of solutions under hard boundary conditions. Based on this, a mathematical framework is devised, with the objective of supplying practical assistance for challenging riser positioning cases, leading to both live visualizations of the riser displacement during its maneuvering and on-the-fly planning of its desired top-end movement.

The new analytical solution is based on a non-causal analysis using the two-sided Laplace Transform. By transforming a set of approximate PDEs that closely resemble those of the complete riser model, we're able to devise improper transfer functions between any two arbitrary points across the riser. Then, an inverse transformation applied to these transfer functions yields convolutions that may be quickly processed. Nonlinear boundary conditions are dealt with via a proposed iterative method.

Quickly computable simulations for the horizontal displacement along the riser's length are presented, allowing for live, simultaneous estimation of the structure's motion at various cross-sections. Likewise, stress/tension estimates at these points are presented in real time.

Furthermore, various top-end trajectories and motion strategies are derived for scenarios previously unsolved in the literature, involving non-static initial conditions, disturbances and time-variable tensions acting on the bottom-end of the riser. This is done to demonstrate the theory's applicability in dire weather conditions.

Finally, the proposed solution is validated and compared to previous results in modeling and trajectory planning of risers. The speed of the presented approach is attested and properly analyzed.
Corrosion in Multiphase Slug Flow Loop in Deep-Water Oil and Gas Exploitation
Authors: Silva Carlos Alberto , Filho David Rodrigues , Nunes Gislaine Maria , Bassani Gabriel Soares , Almeida Neusvaldo Lira , Panossian Zehbour
Published: October 2019

The necessity to reduce cost in handling fluids requires a high flow rates with an inherent risk for turbulence influencing the corrosion process of the involved equipment. These conditions occur especially in offshore environments, as oil and gas production, and in chemical processes and energy production industries. There are several ways to discuss corrosion control associated to multiphase-flow- induced corrosion. One possibility is the mechanistic approach and the other makes use of professionals' practical experiences. A pre-requisite for any effective control practices in multiphase flow induced corrosion is a basic understanding of the involved flow mechanisms. This work presents the study of the influence of slug multiphase flow on API 5L X80 carbon steel pipe corrosion in an environment that simulates oil wells. As a simulated environment, an 80 %water-cut mixture, comprised of 20 % light oil (10 cP) or heavy oil (150 cP) plus 15 % of sodium chloride and 80 % of deionized water, was used. The tests were performed at 40 oC under a different CO2 and H2S partial pressure balanced by N2 to reach a total pressure of 2.5 bar. The tests were conducted in a multiphase simulating loop. All test parameters were monitored to guarantee a slug flow pattern. The conceptual design of the loop allowed the simultaneous evaluation of the influence of the horizontal (0°) and inclined (45°) position of the flow to verify the influence of hydrodynamic effects on the weight loss. The conducted laboratory test results allow the establishment of empirical correlations between the corrosion rate and specific exposure conditions. These correlations may be used in corrosion prediction softwares, which can help an engineer to design and to monitor life expectancies of industrial pipes. Studies conducted in autoclaves and in glass cells produce results which, despite here being useful on the understanding of corrosion mechanisms, are not able to produce multiphase-flow regime results like those related to the conditions of pipelines in oil and gas exploitations. A smaller scale corrosion loop provides a suitable environment for better reproducing hydrodynamic effects on the corrosion of pipe walls. In tests performed in the presence of only CO2, concavities on the carbon steel surface were observed. This was attributed to the flow regime, which allowed the formation of a higher disperse-bubble volume and of an emulsion, either by the formation of an oil-in-water emulsion or a water-in-oil emulsion. However, the increase in CO2 partial pressure promoted, in all tested conditions, an increase of the weight loss rate. Thus, the work allowed scoring basic mechanisms of multiphase-flow-induced corrosion which intensifies the damages of carbon steel pipes in environments containing CO2 and H2S, in different concentrations and in controlled conditions of pressure and temperature.
Recent Updates on Smart Water EOR in Limestone
Authors: Strand Skule , Puntervold Tina
Published: October 2019

Experimental data confirm that the EOR-effects observed during Smart Water flooding can be explained by wettability alteration toward more water-wet conditions. Detailed knowledge about the important crude oil – brine – rock parameters affecting reservoir wetting, fluid flow and wettability alteration in oil reservoirs is needed when Smart Water EOR potential for reservoirs should be predicted.

Both field observations and laboratory experiments confirm that seawater behaves as a Smart Water in limestone reservoirs, significantly improving the oil recovery. Laboratory core experiments have been performed to evaluate the effects of polar components present in crude oil on core wettability during core restoration. Spontaneous imbibition and viscous flooding oil recovery tests have been performed on the restored cores to evaluate the effect of initial core wettability on ultimate oil recoveries. The results have been compared with oil recovery tests that include wettability alteration induced by Smart Water.

The experimental results confirmed that adsorption of polar components in crude oil dictates the core wettability established during the core restoration, and strongly water-wet outcrop cores became mixed-wet. The amount of oil that the core was exposed to affected the degree of water wetness, and therefore the crude oil amount needs to be accounted for in core restoration procedures.

Oil recovery experiments showed that the ultimate oil recovery increased with increasing water wetness in the cores, confirming that increased positive capillary forces, resulting from wettability alteration, significantly affected fluid flow in porous media, improving oil recovery. The results are in line with the proposed chemical Smart water EOR model valid for both carbonate and sandstone. Wettability alteration toward more water-wet conditions induces increased capillary forces and improved microscopic sweep efficiency. Ultimate oil recovery in was significantly influenced by the core wettability, increasing with water wetness, confirming that capillary forces is an important recovery parameter. Only small changes in core wetting have significant effects on ultimate recoveries, confirming that laboratory core restoration procedures need to be optimized when recovery potentials for reservoirs should be estimated.
Application of the Convective-Dispersive Equation to Estimate Field Scale Dispersivity based on a Field Scale Numerical Model and Tracer Production Data
Authors: Cavalcante Filho Jose Sergio De Araujo , Pizarro Jorge Oscar De Sant'Anna
Published: October 2019

The displacement of a given fluid by another in a porous media can occur either in miscible or immiscible conditions. An immiscible displacement happens, for instance, when water displaces oil in a reservoir. It can also occur when the displacing fluid is a gas, if the interfacial tension with the oil is high enough. These processes are usually described by the fractional flow theory, which assumes isothermal flow of two immiscible and incompressible fluids in an one-dimensional, homogeneous porous media; dissipative effects, such as capillary pressure, compressibility and thermal conductivity, are neglected. Miscible floods, on the other hand, can take place in gas-oil displacements when the interfacial tension approaches zero. Common dissipative effects are fingering and dispersion, the former related to mobility ratio magnitudes and the later related to diffusion and velocity contrast commonly caused by the presence of heterogeneities. In miscible displacements through porous media, dispersion is described as the result of diffusion, local velocity gradients, streamlines dimensions in heterogeneous regions, and mechanical mixing into pores. The present work discuss these concepts and relate them to data from an actual deep offshore field. Estimates of field dispersivity by history matching tracer production profiles are based on the analytical solution for the convection-diffusion equation. Gas tracers injected and produced from wells located in the field area were evaluated assuming miscible displacement. The estimated dispersivity allowed the evaluation of mixing/spreading zones. The solution for intermittent tracer injection was used to history match tracer production data. Results shows the scale dependence of the dispersivity, which depends upon the distance and degree of heterogeneity between wells. The field scale dispersivity obtained by history match was coherent with numerical dispersion observed in a field scale numerical model. They were also compared against literature data (laboratory and field scale) in a log-log plot denoting a good agreement of present data with literature.
Development of Deepwater Fields in South America – Available Technologies and Innovative Initiatives
Authors: Aggarwal Rajiv , Carneiro Daniel
Published: October 2019

Offshore industry has about three decades of experience with the development and deployment of floating and subsea technologies in deep (> 500 m) and ultra-deep (> 1,500 m) waters. Most of the ultra-deep water experience has been gained from fields in the Gulf of Mexico, Brazil, and West of Africa. Significant exploration and development activities undergoing in deep and ultra-deep waters of more than eight South American countries require low cost solutions to enable their development.

This Panel will present and discuss the innovative initiatives undertaken by the industry for further development of solutions and technologies for deepwater production facilities (floating and subsea units, risers, umbilicals, flowlines and pipelines) to reduce their capital and operating costs. The innovative initiatives range from variations in the design and execution plans to qualification of specific new technologies. The digitalization of these facilities is also providing means to further reduce capital and operating costs and enhance productivity, safety, and reduce environmental impact. In addition, the potential value from renewable energy to subsea and field operations is being evaluated.

These initiatives are in various stages of development and some are being implemented in deepwater fields in Brazil and Guyana. Several of these innovative technology initiatives will go from Technology Readiness Level (TRL) 5 to 7 in South American fields after operating for more than 3 years.
Artificial Intelligence-Based Screening of Enhanced Oil Recovery Materials for Reservoir-Specific Applications
Authors: Giro Ronaldo , Lima Filho Silas Pereira , Neumann Barros Ferreira Rodrigo , Engel Michael , Steiner Mathias Bernhard
Published: October 2019

The global average Recovery Factor (RF) in oil fields is only about 20-40%. A possible reason for such a low RF might be that Enhanced Oil Recovery (EOR) techniques are not yet broadly applied. This could be for economic reasons, concerns regarding the effectiveness of EOR and potential damage to the reservoir, or the lack of reservoir-specific recommendations.

In this contribution, we introduce a methodology that selects EOR materials for specific reservoir conditions by using Artificial Intelligence (AI) methods. We investigate the consistency of the screening results with the results obtained by state-of-the-art techniques that are used to identify EOR methods only, i.e., without EOR material specificity.

Our method correlates physical and chemical representations of injection fluids, including EOR materials, with reservoir-specific information on lithology, porosity, permeability, as well as oil, water and salt conditions. We have used machine learning on the combined data set in order to provide recommendation for EOR cocktail for injection fluids. Reservoir specific data input on rock, oil, and water conditions available in well logs is transformed by the AI model into a reservoir-specific recommendation of EOR candidate materials for optimized EOR effectiveness. The screening criteria are ranked based on EOR effectiveness and the similarity of key reservoir parameters at pore scale.

Methodologically, a Naïve Bayes Classifier with 10-fold cross-validation over the full training data set classified all instances with an accuracy of up to 90%. In order to compare with the EOR method screening criteria typically used in the industry, we have created a test data set containing instances based on averaged parameter values for representing each EOR method. In this case, our method is capable of classifying the test data set with nearly 100% accuracy. Our methodology allows to produce recommendations for EOR cocktails, including concentrations of their chemical components, for specific reservoir conditions that are readily available through well logs.
Digital Technologies Used in Constructability Design for Surface Installations
Authors: Simas G Torres Milton , Augusto F Rodrigues Breno , Rocha do Nascimento Alexandre
Published: October 2019

During basic design development for new FPSO projects in Brazilian pre-salt exploration, digital technologies were employed, in order to achieve constructability design requirements, construction and commissioning specification checks. Due to its benefit cost, schedule, quality, and overall project objectives and deep influence in platform safety and operability, in a process explained in Figure 1.

Those digital technologies, such as the use of databases, computer aided engineering (CAE), analysis tools, 3D simulations and consistency check, were identified in constructability reviews and were developed to achieve the best constructability procedures and solve construction inconsistencies between several involved disciplines in posterior detailed design, procurement and commissioning phases. This manuscript aims to present the use of digital technologies to support constructability analysis in offshore oil & gas production facility – surface installations - projects of Petrobras.
Floating Deepwater Production Integrity Challenges and Solutions
Authors: Paris Mario Jorge , Constantinis Danny Alexander
Published: October 2019

This paper provides case histories for new methods facilitated by Hull Inspection Techniques & Strategy (HITS) Joint Industry Projects (JIP) including: i) Diverless inspections of hull and mooring systems; and ii) Robotic inspection of cargo oil tanks and pressure vessels. Also, will describe how non-contact thickness measurements by synchronous lasers and big data statistical analysis for inspection scopes are being trialled in the year of 2019 on operating assets. Further innovations around non-intrusive and robotic methods for inspection of electrical systems and pressure vessels, described with case histories supported by business cases, showing how these latest innovations meet the $50-barrel oil industry price target.
The Remarkable Growth of Integrated Subsea Projects from 2016 to 2019
Authors: Labbé David F.L. , Jan Karim , Xavier Marcelo , Tadeu Carlos , Vilchez Marcial
Published: October 2019

Objectives/Scope

The international offshore oil and gas industry started numerous efficiency initiatives in 2014 and 2015 as a response to the global down-turn in field development activity. Additionally new and innovative ways of doing business were conceived and investigated. One of these was integrating the work scopes involved in subsea production and processing systems construction together with associated pipeline and controls infrastructure.

Methods, Procedures, Process

The mechanisms by which integrating the subsea hardware and offshore delivery scopes yields value have been studied and compared with traditional approaches of segmenting the various elements.

Previously executed projects, it was discovered, would have been delivered with different results and imporved cost performance within an integrated structure.

Similarly prospective projects costed and priced using a traditionally segmented approach showed a higher cost and schedule compared with those designed from the early stages of the project by an integrated design team of equipment and installation specialists.

These effects were observed on projects of different sizes and in various geographical regions. (This paper will provide anonymous examples of these cases to provide context).

Our industry currently has more than 15 integrated projects underway and offshore oil and gas operators are starting publicly share their experiences of this new way of working.

The result is that potential field development projects are integrating traditionally segmented subsea scopes earlier in the economic lifecycle of the project. (This paper will illustrate this trend).

As the project execution phase progresses different systems and mechanisms are used to ensure that the value is captured and an acceptable project risk profile is maintained.

Results, Observations, Conclusions

The market for integrated subsea project delivery has grown from 8% of the market in 2015 to 35% or more in 2018 and seems unlikely to diminish in 2019.

Novel/Additive Information

Integrated subsea delivery has emerged as an enabler of different project outcomes for international oil and gas companies and is setting new standards for efficiency in our industry.
Corporate Strategy to Tackle Offshore Drilling Discharge Regulation
Authors: Marinho Leonardo De Souza , Alo Cristiano Pamphili , Loureiro Sebastiao De Andrade , De Oliveira Thiago Judson Lima , Martins Andre Leibsohn
Published: October 2019

This paper provides an overview of the main efforts that are being endeavored by Petrobras in order to contribute for developing a Brazilian regulation for use and discharge of drilling fluids and cuttings from offshore oil and gas operation, based on operational safety, well integrity and environmental aspects.

In early 2018, the Brazilian Environmental Agency launched a Normative Instruction (IN 01/2018) addressing some new conditions for use and discharge of fluids and cuttings from offshore drilling rigs. This regulation is based on the EPA rules, although some relevant points deviate from it, such as the prohibition for discharging drilling fluids and cuttings associated with hydrocarbon reservoir sections. Additionally, this regulation mentions a potential zero discharge by 2022. Due to the challenges for meeting these new requirements and some uncertainty about the real environmental benefits, Petrobras has been developing fundamental and applied studies, research development and protocols in this area.

Petrobras settled an innovative governance model to deal with the new regulation, its consequences and interfaces. It works as a multidisciplinary committee coordinated by an executive manager. It involves a law support for environmental issues and four work fronts, such as (1) linking between internal and external organization (2) guarantee of providing the required infrastructure (3) economical and operational impacts (4) technologies (research, development, studies and protocols) dedicated for related matters. Concerning the forth front, seven important initiatives were initially addressed and cover topics such as operational safety, well integrity – including offshore wells dedicated to cuttings disposal, laboratory protocols and environmental issues. Some relevant studies are those concerning LCA (life cycle analysis), options for avoiding landfill as final cutting disposal onshore and the quantification of oil compounds in drilling fluids and cuttings from the pay zone well section.

The lack of knowledge about the whole impact for onshore destination as drilling waste management strategy, the improvements that still have to be established in order to achieve better operational practices and the comprehension of the input of oil from drilling discharges are the main drivers of this paper. The results help to clarify cloudy topics and, consequently, contribute to create a new basis for building or revisiting some aspects of the present regulation.
Influence of Hole Cleaning on the Liner Cement Job in Papa Terra Field
Authors: Vadinal Rodolfo Balthazar , Perrout Stephan Ribeiro , Chuvas Rodrigo De Campos , Lima Gomes dos Passos Adriano Gouveia , Silva Leonardo Pacheco Da
Published: October 2019

This work presents the lessons learned from the studies carried out to understand the non-fulfillment of the hydraulic isolation required during the liner 10 ¾" cement job. Analyzing the drilling parameters performed and the events of cementing, it is possible that the stationary solids bed and the consequent poor conditioning of the well were probably responsibles for the failure to obtain the hydraulic isolation required for the cementing operation. The investigation report recommends some good practices for avoiding and/or removing the cuttings-bed. The results of some simulations carried out during the investigation studies showed that drillpipe rotation speed contributes significantly to reduce the cuttings-bed height. Additionally to the extended reach, the well studied is a design well, has a complex trajectory, and the computer simulations revealed that ROP control is mandatory to obtain a proper hole cleaning and well conditioning. It was identified that the reduction of the hole diameter has a huge impact on well conditioning, drilling fluid displacement and cement slurry displacement. At last, the paper presents some recommendations for backreaming, mainly for evaluation of ideal operational parameters; adjust the drilling rates according to the hydraulic simulation, to ensure the hole cleaning and optimize the total time of the drilling intervention.
A Feasibility Study of Producing Natural Gas from Subsea Hydrates with Horizontal Snake Wells
Authors: Wan Lifu , Shaibu Rashid , Hou Xuejun , Guo Boyun
Published: October 2019

This study focuses on technical feasibility of producing natural gas from offshore gas hydrate deposits using a new technique called horizontal snake wells (HSW). This paper addresses engineering and well productivity issues for the new technique. Coiled tubing string is proposed to drill HSW in gas hydrate reservoirs for increasing well productivity and reducing wellbore collapse problems. A new analytical model was derived to predict of maximum achievable wellbore length (MAWL) based on the theory of buckling failure. Furui's equation for gas reservoirs was used for predicting the initial well productivity at the MAWL. Gas lift method is proposed to remove water for achieving a constant bottom hole pressure that is slightly below the hydrate dissociation pressure. Gas production forecast was made on the basis of material balance. Net present value (NPV) method is employed to perform economics analysis. A gas hydrate reservoir in the South China Sea was taken as an example to investigate the feasibility of producing natural gas from gas hydrate deposits using the HSW technique. The new analytical model gave the MAWL under extreme well friction conditions prior to buckling failure of coiled tubing. Furui's equation predicted commercial well productivity at the MAWL, depending on the loop separation of the HSW. If the bottom pressure is maintained with gas lift technique at a constant level slightly lower than the hydrate dissociation pressure to prevent wellbore collapse, material balance forecasted high NPV of HSW. It is concluded that the HSW is a feasible technique for economically producing natural gas from offshore gas hydrate deposits. This paper presents a novel method called HSW for producing natural gas from offshore gas hydrate deposits. It also demonstrates how to evaluate the productivity and thus economics of the HSW.
Influence of Asphaltene Inhibitors on Wax and Asphaltene Deposition - Are Problems Associated?
Authors: Aguiar Janaina I. S. , Punase Abhishek , Mazzeo Claudia
Published: October 2019

Organic deposition formed at high temperatures in oil and gas production systems is commonly linked to instability of asphaltenes. Recent studies revealed that deposits collected in offshore production wells produced in Gulf of Mexico exhibited compositional variation pointing to a more complex fouling process than solely related to the asphaltene fractions. To better understand the mechanism of deposition and external factors that could contribute to this precipitation, crude oils and their respective deposits collected from the field were characterized for comparison in terms of properties and composition. Moreover, crude oils were treated with Asphaltene Inhibitors (AI) and Paraffin Inhibitor (PI) and tested applying three techniques: Asphaltene Dynamic Deposition Loop (ADDL), cold finger and rheology. The deposits collected from the ADDL and from cold finger were analyzed and compared to the field deposits. A lab-to-field correlation was observed when analyzing the deposits collected from the ADDL and cold finger tests. In both deposits, asphaltenes and wax fractions were observed to co-precipitate and form "Waxphaltenes". The efficiency of the AI on dispersing the asphaltenes was observed to have a major impact on the precipitation as possibly increasing the deposition of microcrystalline waxes. The influence of the AI at certain dosage rate in the precipitation of waxes is highlighted. In this research, the mechanism of asphaltene dispersion and instability of waxes in the presence of AI at low concentrations is proposed.
Conceptual Design of a Large Water Treatment System for Offshore Smart Water Injection
Authors: Machado Bernardo Farah , Vale Osvaldo Roberto , Pivatto Bruno Coccaro , Motta Leticia Santos , Cavaliere Carlos Carreiro , Souza Marcus Vinicius
Published: October 2019

Water injection is a traditional method of secondary recovery used in the petroleum industry. Typically, even with the injection of water supplementing the initial energy of the reservoirs (primary recovery), less than 50% of the original volume of oil is produced. By altering the chemical composition of the injected water, tests performed in laboratory and in pilot units have shown significant oil recovery (5 to 40%), when compared with a field with traditional water injection. The oil industry has shown great interest in smart water (SMW). Basically, the SMW comprises a seawater stream with altered ionic composition and low total dissolved solids (TDS). Membrane separation is the most suitable method for producing SMW offshore, though, it has some limitations for water ion tuning. Reverse Osmosis (RO) membrane technology plays an important role in SMW generation process due to its hability to promote a high rejection for all ionics species.

This paper describes the results of a topside conceptual design of a 39,500 m3/d Water Treatment System to produce SMW (WTSMW), that generates water with a TDS of 1,884 mg/l, from seawater with 40,000 mg/l of salt. The treatment scheme comprises RO membrane permeate plus seawater, with a device to recover energy from the RO reject stream. The product water is also used for oil desalting and may be used for membrane cleaning. Electrical consumption, weight and footprint were compared with a sulphate removal unit (SRU) of 35,400 m3/d, of an existing 150 Kbpd floating production storage and offloading unit (FPSO) used as reference design (RDF). It was also evaluated the suitability of the RDF to incorporate the WTSMW, concerning electrical consumption, weight and footprint. The WTSMW is heavier (571 t), requires one more module level, which resulted in a module 9 m higher, and consumes more energy (3.3 MW), despite the use of the energy recovery device (ERD). To receive the WTSMW, the generation nominal capacity (4 × 23 MW) of the RDF should be changed to 4 × 28 MW. The increase in height and weight do not represent any restriction for design or construction of a new production unit to include the WTSMW.
Influence of Whipping on the Structural Response of the Flare Tower Foundations of a Typical Spread Moored FPSO
Authors: Benhamou Alexis , Shimazaki Junji , Bontemps Fabrice
Published: October 2019

Typical ship-like floating bodies, for certain operating conditions, may experience large slamming loads in the bow or aft parts of the vessel. In addition to the local structural damages induced by slamming, a significant global hull vibration might also be excited. This vibratory response, referred to as whipping phenomenon, is usually not considered in the offshore industry, in particular in the design of ship shaped FPSOs. However, in case of resonance with slender structures such as the flare tower, these effects can have a strong influence on the fatigue performance at the interface between the FPSO’s hull and those structures. The objective of the work presented in this paper is to assess the influence of these effects on the total fatigue damage.

Numerical modelling of whipping is extremely complex from several aspects and only approximate models exist today. For this study, a state of the art whipping model is used, which couples the hydrodynamic loads (linear diffraction and radiation, nonlinear incident and slamming) with dynamic structural response of the floating body. The hydrodynamic part of the model includes a weakly nonlinear diffraction-radiation tool which is supplemented by a modified Logvinovich model for slamming. These hydrodynamic models are fully coupled with the structural vessel dynamics which are represented by a simplified finite element model. Direct assessment of hot spot stresses are performed on refined fatigue models.

Typical FPSO’s design includes the flare tower installed in the fore part, where the accelerations induced by the hull girder global vibrations are the highest. If the natural frequency of the flare tower is close to the natural frequency of the hull girder, significant flare vibrations might occur. In addition, spread moored FPSOs receive wave loads from 360 degrees and since typical FPSOs’ hull shape is similar to oil tankers’ hull shape, its stern flare is relatively larger flare than its bow flare. If waves come from the stern and FPSO’s draft is shallow, hull vibration induced by stern slamming might be large. The present work evaluates the influence of these vibrations on the flare tower structural response. The deterministic results are used within a dedicated methodology allowing for the evaluation of fatigue life of the structural details.

This work proposes an innovative methodology for including the influence of highly nonlinear loads, such as slamming induced whipping, in the structural fatigue assessment of offshore structures.
Subsea X-Mas Tree Standardization Benefits in Brazil Scenario
Authors: Beppler Veloso Raphael , Rabello Pereira Alexandre , Ramos Roberto Augustus Marcello
Published: October 2019

1. Abstract

Subsea X-Mas Trees have been standardized in Brazil since the 1990’s and this paper will present how this standardization was evolved throughout the years and the main benefits achieved to both, the operator and the suppliers.

To achieve the standardization benefits the X-Mas Trees standardization program has followed three main approaches: -The first is related to standardization of X-Mas Tree application, becoming it possible to use any X-mas Tree from any supplier in the production or injection wells, in the most possible cases.-The Second is related to standardization of X-Mas Tree interfaces between sub-equipment and between the equipment and its tools.-The third is related to standardization of manufacturing, qualification program and inspection.

At the beginning, only the interfaces between the THS (Tubing Head Spool), TH (Tubing Hanger) and the X-Mas Tree itself were standardized. Throughout the years, more interfaces were standardized, such as Tree Cap, Flowline Connectors and Control Systems.

The standardization may lead to very big scale gains and cost reduction when is possible to look the whole projects as a portfolio, as it makes possible to combine several projects into a Bidding process (bid), enabling better competitiveness in the supplier market. For example, bids with up to 300 X-Mas Trees split in lots with up to around 130 X-Mas Tree per supplier were carried out in Post-Salt and Pre-salt projects and a huge benefit was achieved with this strategy.

In addition, the standardization brings better stock management as the projects’ schedule changes over time, minimizing the time the X-Mas Trees stay in stock. At last, it enables faster project implementation, once the equipment is already contracted, designed and, sometimes, even manufactured.

Standardization of the X-Mas interfaces brings the possibility of exchanging sub-equipment of different suppliers, as vertical connector modules, for example, between any well. This is extremely useful when there are operational issues during the installation, as it becomes possible to use equipment from another supplier until the issue is outlined. Besides that, there is another standardization benefit, regarding to wells maintenance, where the equipment removed from a well can technically be reused in another well.

Additionally, when multiplexed X-Mas Trees became the standard in Brazil for Pre-Salt wells (in the past, all multiplexed controls were located on Manifolds), it was imperative to standardize the control system interfaces, enabling it to be from a different supplier than the X-Mas Tree itself, as well.

Standardization of X-Mas Trees enabled the operator to better answer to its projects demand in a portfolio view, reducing costs, increasing flexibility and allowing the competitiveness between suppliers in all project phases.
A Practical Model for Production Forecast of Fractured Vertical Well in Coalbed Methane Reservoirs: Dynamic-Drainage-Area Concept
Authors: Sun Zheng , Wu Keliu , Shi Juntai , Fu Jin , Shao Changchun , Zhou Yu , Liu Chengyuan , Jia Yanran , Fang Jinhui , Lv Ming
Published: October 2019

A great deal of attention has been attracted to the exploitation as well as the development of unconventional gas reservoirs, which expect to act as an essential role in counterpoising the daily increasing energy demand around the world. In this research, with the intent of contributing to the successful development of coalbed methane (CBM) reservoirs, which is an indispensable member of the family of unconventional gas reservoirs, a novel production prediction model is proposed for fractured vertical CBM wells. The main difference of the research compared with previous excellent documents is taking the effect of pressure propagation behavior on production performance of CBM wells into account. In general, CBM reservoirs possess the low-permeability (<1 mD) physical property, which results in the slow pressure propagation speed during the whole production life. More importantly, because of the unique gas desorption effect inside coal matrix system, more and more adsorption gas will enter into coal cleat system with the production proceed, which will accumulate the formation energy and further mitigate the pressure propagation speed. As a result, it is a relatively time-lengthy period for the pressure propagation process with regard to CBM reservoirs, which currently has not been detailed and comprehensively analyzed. Additionally, it should be noted that the formation pressure is a key sensitive parameter affecting production performance of CBM wells, resulting from the fact that gas production rate takes place only when formation pressure is lower than critical desorption pressure. In this view, the pressure propagation behavior shows a close relationship with production performance of CBM wells, which however fails to receive due attention up to date. In these regards, research content in this paper attempts to shed light on the effect of pressure propagation behavior on production performance of CBM wells from both theoretical and application scopes. With the capacity of capturing the pressure propagation behavior, a novel production prediction model is proposed for fractured vertical CBM wells, the reliability and accuracy of which has been well verified by numerical simulator. Also, the pressure propagation details during production process can be characterized by the proposed model, which is supposed to be highlighted as the main novel point when comparing with previous models. The proposed model is able to generate sensible production performance with less input parameters and calculation time than that of a full-calibrated numerical simulator. Furthermore, details of formation pressure variation regularity are clearly presented by the proposed model, which provides a completely new pathway to evaluate and optimize production performance of fractured vertical CBM wells.