bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Optical Absorption and Structural Bonding of Lithium Zinc Phosphate Glasses
Authors: Nurul Ain A.M. , Sahar Md Rahim , Sazali E.S. , Azman K. , Norihan Yahya
Published: October 2017

Glasses with chemical composition of (60-x)P2O5-25ZnO-(15+x)Li2O with 0.0 ≤ x ≤ 5.0 mol % are prepared by melt quenching technique. The physical properties, by mean of density and molar volume are determined. The amorphous nature, absorption and structural behaviour are characterized using X-ray Diffraction (XRD), Ultraviolet-visible-near infrared (UV-Vis-NIR) and Fourier transform infrared (FTIR) respectively. In this work, the glass densities are found increases in the range of 2.70 - 2.78 gcm-3 and molar volume decreases from 37.48 - 40.75 gcm-3 with respect to Li2O concentration. Meanwhile, the optical band gap energy for direct and indirect transition are found decreases from 3.074 eV to 2.525 eV and 2.699 eV to 1.670 eV respectively. The Urbach energy is varies as Li2O content increases. The refractive index of these glasses is ranging from 2.48 to 2.90. FTIR spectra exhibited seven bands which centered at 512 cm−1, 767 cm−1, 918 cm−1, 1087 cm−1, 1281 cm−1, 1627 cm−1 and 3441 cm−1 wavenumber that assigned as vibration of Zn-O, symmetric stretching vibration of P-O-P rings, asymmetric stretching vibration of P-O-P groups, asymmetric stretching of PO2-group, asymmetric stretching vibration P=O, bending vibration of water molecule and fundamental stretching of hydroxyl group.
Effect of ZrF4 on the Physical and Absorption Properties of Magnesium Tellurite Glass
Authors: Md Zain S.K. , Sahar Md Rahim , Sazali E.S.
Published: October 2017

Tellurite glass containing zirconium fluoride (ZrF4) with composition of (90-x)TeO2-10MgO-(x)ZrF4,where 0.0 ≤ x ≤ 6.0 in mol% has successfully been prepared by melt quenching technique. X-Ray Diffraction (XRD) pattern verified the amorphous nature of the glass. In this study, the physical and optical properties were investigated in term of density and absorption properties by using Archimedes method and UV-Vis Spectroscopy. It was found that glass density decreases in the range of 4.842 – 4.995 g cm-3 with the increase of ZrF4 concentration. Meanwhile, the molar volume is increased in the range from 29.566 to 30.593 cm3/mol with increase of ZrF4. The absorption edge is found to shift toward a higher wavelength as the ZrF4 concentration is increased. On the other hand, the optical energy band gap shows the decrement from 2.573 to 2.212 eV for indirect transition and from 3.044 to 2.927 eV for direct transition with the addition of ZrF4 concentration while the Urbach energy, increases from 0.302 to 0.498 eV with the increase of ZrF4. All the results will be discussed with respect to the glass composition.
Enhanced Cement Bond Evaluation in Thick Casing Utilizing Guided Acoustic Modes Generated by Electromagnetic Acoustic Transducers
Authors: Patterson D. , Ingram S. , Matuszyk P. J. , Yao X. , Das R. , Steinsiek R.
Published: October 2017

Well integrity and zonal isolation are crucial in deepwater wells requiring accurate cement bond log analysis. These wells require high mud weights and/or thick-wall casing strings that can prevent the use of some tools and, in the best case, result in a significantly reduced response and senstivity to the presence of cement. Guided Shear Horizontal (SH) modes generated by electromagnetic acoustic transducers (EMATs) provide an enhanced dynamic range response and are immune to any borehole content, either liquid or gas.

The response of SH modes is evaluated over a range of different casing diameters and thicknesses commonly encountered in deepwater wells in Brazil. This analysis includes analytical and numerical modeling that shows the changing attenuation response to varying cement properties. The unique feature of the SH modes is their response to only a solid coupled to the casing, enabling a straightforward analysis and interpretation. These results are also compared to standard compressional attenuation, demonstrating the enhanced sensitivity that the EMAT measurement provides.

The results demonstrate that the enhanced dynamic range of the SH modes often provides 300% or larger cement attenaution response over the standard compressional methods. This enhanced SH mode range shows the ability to use these data to directly determine the shear modulus of the material coupled to the casing, enabling a straightforward method for determining the presence of cement and its properties in-situ. This approach contrasts with conventional ultrasonic systems that respond to the compressional impedance, which can often have complications with heavy settled-solids behind the pipe. In addition, a case study shows the ability to see the formation-squeeze in heavy wall pipe. This evidence demonstrates the ability of SH guided modes generated by EMATs to provide enhanced cement evaluation in thick-wall casing. These modes provide an enhanced dynamic range and a straightforward and unique means determining the presence of a solid and its properties.
Lessons Learned and Reduction in Rig Time with the Use of Water-Based Mud to Bottom Hole Drilling in the Pre-Salt
Authors: Vadinal R. B. , Fabri F. , Teixeira G. T. , Gonzaga K. A. , da Silva P. H. P
Published: October 2017

The drilling of the evaporitic section using water-based mud (WBM) was always a challenge: even though there are already some wells drilled with saturated aqueous fluid, their use still divides opinions within the technical-academic community of the oil industry. Basically, there are two currents: one that believes that salt drilling with WBM causes an enlargement so great that it becomes impracticable to cement the casing and, consequently, to obtain a leak off test (LOT) or a formation integrity test (FIT) sufficient for drilling of the next phase. The other line of thinking is based on that the break-in created by the WBM is similar to that caused by the synthetic-based mud (SBM) and this increase in diameter would not have a negative influence on the quality of the cementing job. In 2015-2016, Petrobras drilled 13 wells in Santos Basin Pre-Salt using WBM for bottom hole drilling (BHD). In this way, this work aims to report the lessons learned in each well, comparing fluid costs with correlation wells drilled with SBM's. The use of WBM, besides not negatively impacting the drilling time of the phases, allows a reduction of the costs with chemicals products and a decrease in equipment costs, since the drying system of cuttings is not used. In addition, rig and borehole cleaning are simpler and require less time and WBM is less aggressive for people working in direct contact with the drilling fluid. To compare the costs of fabrication and treatment of fluids, an average calculation was used for the correlation wells. Thus, an economy achieved is the difference between average cost for correlation wells and the well in question. The drilling of the evaporitic section with WBM's makes: (i) no significant salt washout than that obtained when using SBM and (ii) as WBM does not require a cuttings drying system, rate of penetration (ROP) obtained during a salt drilling are higher than those obtained when working with SBM. For the drilling of the carbonate reservoir, the performance of WBM is similar to that of SBM and the use of WBM in BHD allows faster fluid exchange and generates less residue for wells with open hole single completions. By drilling 13 wells using WBM, it was possible to save 576.9 hours of rig time.
Cableless Intelligent Well Completion Development Based on Reliability
Authors: Da Silva M. F. , Jacinto C. C. , Hernalsteens C. , Nobrega M. , Soares M. Defilippo , Schnitzler E. , Nardi L. B.
Published: October 2017

This paper describes how the Pre-Salt reservoir monitoring & control requirements in Brazil, and the pressure to minimize CAPEX, OPEX, and ABEX pushed for the development of a cableless intelligent well completion based on reliability. The development plan proposed is associated with an appropriate risk assessment to ensure lower risk at each project phase.

The X-ware (hardware, software and human) reliability methodology is used throughout the development. It starts with a complete understanding of environmental and operational conditions, needed/requested materials and well design. Then, reliability assessments based on physics-of-failure methods is used to incorporate reliability into the hardware design process and continuous time non-homogenous semi-Markov process to capture human/software reliability. Finally, to ensure a lower risk at each project phase, complexity theory is used to evaluate the overall risk.

This development of a cableless intelligent completion addresses monitoring and control for up to four reservoir zones on producing, injection and convertible wells, all of them in a subsea environment where scaling and lost circulation problems are likely to happen. Reliability of at least 90% in 30 years with 80% of confidence interval is the major challenge of this development. The critical paths to ensure the achievements are cableless telemetry and the energy harvesting for the life cycle of the well. The expected results for the development are: expedite technology readiness with lower risk during installation and higher availability during the life cycle of the well.

The development of new technologies using X-ware reliability methodology and technical risk as a process control variable is the main contribution of this paper.
An Integrated Field Development Methodology for Improving FEL1
Authors: Nunes Giovani , Costa André Luiz Hemerly , Romão Josenilton de Figueiredo
Published: October 2017

The discovery of an oil field results from extensive exploratory work, culminating in its declaration of commerciality. To estimate the recoverable volume of oil and determine the net present value (NPV) of the project, a conceptual study of the production system is made. Given the (inherent) uncertainties of the exploration stage, the information and models used to support such studies tend to have low accuracy. The treatment of uncertainties is done with additional information acquired along the project. This is the case of well tests to mitigate reservoir uncertainties. However, a methodology able to capture the most relevant aspects of the NPV through the integration of different disciplines (reservoir engineering, flow assurance, topsides, etc.), without this entailing lengthy and complex simulations, is still an unmet demand.

Looking for inspiration in analogous systems and successful projects is the usual way the industry deals with uncertainties, which is why the concepts for new projects tend to be similar to those of the past. While this attitude brings comfort to decision makers, there is a risk of losing the opportunity to add value to the project through a more profitable alternative concept.

In the case of large oil fields, most companies will try to urgently put them to production, since the postponement of revenue reduces its NPV. This can lead to the development of fast track projects, restricting the time of alternative studies. Again, it is important to improve the decision-making process.

This work aims to present a methodology for conceptual studies through the integrated simulation of different disciplines. This methodology uses the NPV as a parameter in the generation of exploratory numbers of pre-projects and creates a criterion for the selection of a subset to be evaluated in following phases. The aim is to evaluate, for example, the ideal number and capacity of platforms in a field, the convenience of "phasing" or not of the construction of wells, a criteria for choosing flexible or rigid risers, the gains obtained with the increase in diameter of risers and production lines, etc.
Evolution of Control Strategies to Minimize Pressure Fluctuation During Connections in MPD Deepwater Operations
Authors: Grein E. A. , Dannenhauer C. E. , Cruz M. S. , Silva F. R. G. da , Martins A. L. , Vanni G. S. , Ribeiro V. J. S. , Vega M. P.
Published: October 2017

MPD techniques are used nowadays to precisely control the pressure profile throughout the wellbore. They are usually employed in drilling with narrow pressure windows, such as through highly fractured reservoirs, regions near depleted wells, regions with small fracture pressure, among others. Low drilling pressures may result in undesirable influxes from reservoir fluids, whereas high drilling pressures may cause mud loss and may damage the near-well region, reducing the future well productivity. This work details the development of a MPD simulator (hydraulics and control strategy).

The hydraulic model is transient and based on the explicit and simultaneous solution of mass and momentum flow equations. This model is different from the usual control purpose hydraulic models since the well geometry is actually discretized, allowing a more precise determination of the pressure profile along the well. Furthermore, this discretization also enables the simulation of the delay between an action at the choke and the corresponding response at the bottom hole, which is fundamental for a realistic evaluation of a control strategy. A nonlinear control strategy was also created in this work. This strategy is based on the aim of a smooth exponential evolution of the choke pressure until it reaches its setpoint. The execution of the hydraulic simulation several times is not required, as in typical model predictive controllers (MPCs). The control strategy is also not so susceptible to control parameters, as in PID classical controllers. An experimental drilling plant was employed for validating the nonlinear control strategy. The nonlinear control algorithm and the classic control scheme were compared. Using real-time measurements, the automated continuous drilling unit performance is analyzed under a scenario of flow disturbance. The fast and precise hydraulic model coupled with an efficient control method makes the present simulator feasible for real-time applications.
Methodology to Improve Miscible Gas Injection Forecast Based on a Field Scale Simulation Model
Authors: Rios V. S. , Santos L. O. S , Quadros F. B. , Lykawka R. , Schiozer D. J.
Published: October 2017

The use of coarse scales in reservoir simulation is necessary to reduce computational time; however it can degenerate results due to loss of resolution of the small-scale phenomena, especially in oil fields in which a miscible gas is injected in an enhanced oil recovery method. Errors of the upscaling process are usually mitigated with the use of pseudo relative permeability curves. In cases of miscible gas injection, these techniques cannot be used directly, since there is no saturation variation. Therefore, the proposed methodology is based on employing a fluid model with a minimum miscibility pressure (MMP) above experimental values in order to ensure an immiscible displacement. This solution does not violate the phase behavior and ensures formation of two hydrocarbon phases in the reservoir. Therefore, the gas relative permeability plays a role in the simulation results and can be used to better fit the refined model production curves. In this study, problems that occur when upscaling is applied in various levels of refinement, from fine-scale grid (necessary to preserve geological characteristics) to simulation grid (necessary to preserve flow characteristics) in large fields with miscible gas injection were investigated. As expected, (1) simulations in coarser scales were not able to represent small-scale phenomena and (2) an increased numerical dispersion effect was observed and evaluated with higher order numerical schemes. An alternative solution to better reproduce small-scale production curves using a coarser scale model and a modified fluid model is proposed.
WSOG and Emergency Disconnection Guidelines
Authors: Cruz Daniel Ferreira , Fonseca Diogo da Rocha
Published: October 2017

Dynamic Positioning (DP) systems are becoming more and more used in the Oil and Gas Industry. Over the last decades, the escalation in deep-water exploration and development resulted in an increased number of dynamic positioned rigs. But despite the increasing improvements in technology and capability, there is always a risk of a loss of position due to equipment failures or human errors. In consequence of such event, the DP drilling unit must be able to rapidly shut in the well and disconnect the BOP. Failure during an emergency disconnect procedure may result in damages to the rig, riser, wellhead, and, in worst case, an uncontrolled subsea blowout.

Emergency disconnection may occurs at any time in dynamic positioning drilling rigs, as a result of a sudden blackout or by a quick drive-off, for instance. Because of that, all emergency procedures should be well understood by both DP and drill floor personnel. It is imperative that the risks of a position loss are previously assessed in order to reduce the potential damage caused by a disconnection.

The two most relevant tools for reducing the impact related to the DP System failure are the Well Specific Operating Guidelines (WSOG) and the Emergency Disconnection Guidelines. The WSOG defines four diferent DP Status associated to a specificrig executing a specific operation and using specific equipments and its performance limits - "Normal Status," "Advisory Status," "Yellow Status" and "Red Status". The Emergency Disconnection Guidelines establish the actions in case of reaching each of these status. Emergency Disconnection Guidelines were established for various drilling, completion and workover operations, to be studied and discussed previously activities with BOP / Christmas Tree connected to the wellhead.

The main goal of this paper is to present how the WSOG and the Emergency Disconnection Guidelines work together, bringing statistics and lessons learned of loss of position and emergency disconnections. Additionally, this work suggests emergency disconnect sequence (EDS) options for different operations and BOP configurations (number/type of shear rams available).
Estimation of Diesel Supply Vessels in Offshore Oil & Gas Activities Through Dynamic Simulation
Authors: Silva Victor Anselmo , Moreira Pedro Chaves Meurer , Leite Ricardo Penna
Published: October 2017

This paper focus on the problem of estimating a fleet of supply vessels dedicated to transport diesel consumed by offshore oil and gas installations at Campos Basin, Brazil. Such problem has been widely tackled by several publications, most of them employing traditional deterministic approaches such classical optimization or other heuristic methods, despite of the intrinsic stochastic components the area encompasses. Hence, this work analyzes the problem based on discrete-event dynamic simulation considering uncertainty present in offshore operations. The main results are organized in terms of lead time curves. Then a hypothetical case analysis is conducted, from which it is possible to have more robust fleet estimation, as well as an amplified comprehension on the impact of uncertainty in logistics and offshore operations.
Integration of Ensemble Data Assimilation and Deep Learning for History Matching Facies Models
Authors: Canchumuni Smith Arauco , Emerick Alexandre A. , Pacheco Marco Aurelio
Published: October 2017

Ensemble data assimilation methods have been applied with remarkable success in several real-life history-matching problems. However, because these methods rely on Gaussian assumptions, their performance is severely degraded when the prior geology is described in terms of complex facies distributions. This fact motivated an intense investigation reported in the literature to develop efficient and robust parameterizations. Despite the large number of publications, preserving plausible geological features when updating facies models is still one of the main challenges with ensemble-based history matching.

This work reports our initial results towards the development of a robust parameterization based on Deep Learning (DL) for proper history matching of facies models with ensemble methods. The process begins with a set of prior facies realizations, which are used for training a DL network. DL identifies the main features of the facies images, allowing the construction of a reduced parameterization of the models. This parameterization is transformed to follow a Gaussian distribution, which is updated to account for the dynamic observed data using the method known as ensemble smoother with multiple data assimilation (ES-MDA). After each data assimilation, DL is used to reconstruct the facies models based on the initial learning. The proposed method is tested in a synthetic history-matching problem based on the well-known PUNQ-S3 case. We compare the results of the proposed method against the standard ES-MDA (with no parameterization) and another parameterization based on principal component analysis.
Offshore Production Loop Decommissioning Using Filter Press and Oil-Absorbent Media
Authors: Ewbamk Guilherme
Published: October 2017

This paper presents the results obtained from decommissioning an offshore production loop (7.625 in., 19 km) by flushing with inhibited seawater and compares flow-assurance software simulations to data collected in the field.

After completion of the subsea production system shutdown, the production loop was pigged for dead oil removal, which was routed into the production unit separator. Once the dead oil was removed, the system was configured into a closed loop and flushed with a filtration spread (slurry skid, filter press, and polishing filter) to reduce the oil and grease content. Oil-absorbent additive was added to the typical oilfield diatomaceous earth filtration process, and the system was flushed until the oil-in-water content was reduced to less than 29 ppm (to meet local regulations). The completion of flushing for oil removal allowed for the disconnection and replacement of subsea structures, such as jumpers and manifold, in compliance with local regulations for oil-in-water content.

During the engineering phase before the offshore campaign, flow-assurance software simulations were used to verify that the proposed methodology would achieve the planned results. Based on these simulations, the production loop needed to be flushed 5.6 times its total volume to achieve the oil-in-water content specification. The offshore campaign required 5.9 flushes of the entire production loop volume and achieved an oil-in-water content of 3 ppm. Although software simulations and field results were similar, early filter-press saturation and washout produced issues during operations. For future operations, using an oily water separator before the filter press is recommended to extend the life of filtration/oil-absorbent media. The methodology validates the use of a filter press with oil-absorbent media as a cost-effective solution for oil removal in riser production or water injection loop systems.

The presented application is typically used during routine completion fluid diatomaceous earth filtration with no significant impact on filtration performance. Oil removal in compliance with the environmental limitations of oil and grease was successfully implemented for the production loop decommissioning and can be used in other systems with similar configurations.
Artificial Intelligence Strategy Minimizes Lost Circulation Non-Productive Time in Brazilian Deep Water Pre-Salt
Authors: Leite Cristofaro R. A. , Longhin G. A. , Waldmann A. A. , de Sá C. H. M. , Vadinal R. B. , Gonzaga K. A. , Martins A. L.
Published: October 2017

Fluid losses are still today one of the most challenging problems in well construction. The scenarios faced by operators during development and exploratory campaigns in the deep water pre-salt area are characterized by natural fractures, vugs and caves. Therefore, problems related to loss of circulation are critical, increasing the non-productive time and consequently, well construction costs. Additionally, in several situations, conventional drilling limitations prevent the reaching of the well target.

The present study proposes the application of a methodology to define optimum loss control material (cross-linked pills, fluid loss squeeze, bridging agents, cement), among those available for each situation, to minimize lost circulation events during drilling operations.

An Artificial Intelligence strategy based on Supervised Learning was defined to generalize data collected from five hundred lost circulation events over a three years period. Human Computer Interaction principles were used on the development of an interface where the field engineer can interact with training data while having little to no Machine Learning knowledge.

The use of empirical analysis and learning strategies as tools to assist the decision making process in the form of lost circulation countermeasures is described by this paper. The method was validated on data collected from several different wells in the Santos Basin, Brazil, pre-salt area. The strategy was already applied in two real cases resulting in a six days well construction time saving.
Multirate Timestepping For Mooring Line Dynamics
Authors: Low Chee Meng , Ng Eddie Yin-Kwee , Srikanth Narasimalu , Chua Kie Hian
Published: October 2017

Direct time integration is a widely-used method for the analysis of loads and motions of mooring and floating systems. Nonlinear and transient effects can be easily accounted for in time domain analyses but it is a computationally expensive method, especially for explicit solvers which are limited by the timestep size to meet numerical stability requirements. There is potential in using multirate time to reduce computation times. This paper presents the development and evaluation of a multirate timestepping algorithm based on the Modified Euler integration method for the solution of mooring dynamics. The temporal synchronization as well as spatial boundary conditions needed for coupling the partitioned line segments with different spatial discretizations are presented. The stability parameters and gains in computational efficiency of the method are evaluated with numerical experiments based on a simple test case.
Heavy Denier High Performance Polyester Yarns for Deep Water Offshore Mooring Ropes
Authors: Bastos Milton Briguet , Haach Leandro , Tomazi Alexandre , Fernandes Elieti Biques
Published: October 2017

Scope/Objectives: In order to meet the technical challenges of larger platforms in ultra-deep water (> 1500 meter), both mooring rope as well as yarn producers have to improve tenacity and modulus as compared with mooring systems developed for deep water (500-1500 m) since mid-1990's. The purpose of this study is to evaluate this new breed of High Modulus and High Tenacity polyester yarn.

Methods, Procedures, Process

1. Yarn development: two of the largest global producers of industrial polyester yarns invested heavily in new production capacity and state-of-the-art polymer (LSP – Liquid State Polymerization) and multi-end spinning/drawing with Induction Godet duos with the advantage of using the same low cost raw materials of traditional industrial polyester yarn. The objective is to produce heavier denier yarns with superior tenacity and modulus with lower variability; 2. Rope construction development and sub-rope evaluation: the traditional method to make strands for a sub-rope uses a twisted multi-ply polyester yarn with a final titer of 40-100 thousand denier as a base. Recent development indicated that this rope construction is not effective since twisting yarn reduces rope tenacity and increase elongation at a specified load (reduce stiffness).

Results, Observations, Conclusions: Guxiandao developed a HT/HM 3000 denier (G3014HQ) in 2011 with better mechanical properties than the traditional 2000 denier been used extensively the last 20 years. The characteristics of this yarn were used as a starting point for further yarn improvement with even higher tenacity, modulus in a heavier (6000 denier) put-up. Evaluation tests are performed on sub-ropes based on the conclusion from previous papers that mechanical properties of sub-ropes are highly correlated with test results from full size ropes. Sub-ropes of both 3000 and 6000 denier were produced with the same designed Breaking Strength at Lankhorst Brazil and Portugal.

Novel/Additive Information: Similar sub-ropes produced using heavier denier showed a higher tenacity (+2%), reduce MBS test result variability and improved stiffness. Reducing the number of sub-ropes also increases the efficiency of rope making process and improve MBL. Using a heavier denier yarn is key to meet the future trend in mooring rope construction that uses larger sub-ropes. Considering stronger and stiffer ropes in mooring system design model could result in the reduction of the number of mooring lines required for a certain FPSO.
Reynolds Number Influence on Wax Deposition
Authors: Albagli R. C. , Souza L. B. , Nieckele A. O.
Published: October 2017

Wax deposition is a phenomenon present in oil production systems (mainly in deep water due to the low temperatures), which consists in the adhesion of solids fractions of hydrocarbon to tubing and lines, reducing the area opened to flow until eventually being completely blocked. The comprehension of the mechanisms that influences in the deposition has not yet been fully achieved. Given the relevance of this kind of system in new fields' development and the absence of a theory able to explain the deposit's evolution and characteristics, the production limitation caused by this phenomenon is one of the main issues in flow assurance. The flow regime in production lines can vary from laminar to turbulent. Therefore, the influence of the Reynolds number in the deposition phenomena is investigated. To represent the turbulence, a two equation κ-ω turbulence model coupled to the enthalpy-porosity model, where the deposit is a porous media, was developed. From a thermodynamic equilibrium, the species that comes out of solution are determined while their concentration distribution is determined by each molar conservation equation. The conservations equations were solved with the finite volume method, employing the Power-law and implicit Euler schemes to handle the spatial and temporal discretization. Comparison with controlled experiments in an annular section was performed with reasonable agreement for the deposition thickness, especially for steady state. The deposit's thickness reduction with the Reynold number increase was verified. The influence of the flow regime from laminar to turbulent is examined through the deposit thickness, velocity, temperature and species fields.
Tailored and Reliable Method for Cement Plug Improves Times in Deep Water
Authors: Souza Leonardo , Sasso Alejandro De La Cruz , Munoz Hector
Published: October 2017

End-of-well operations can improve drilling performance through selection of the proper tools to optimize rig time and tailoring solutions. For deepwater projects, it is necessary to optimize costs without compromising safety and quality while delivering maximum efficiency. An innovative technique is presented for placing a long cementing plug using sacrificial tubing and a special tool. This method also allowed checking the top of cement (TOC) after a short waiting on cement (WOC) period. Plugging and abandonment operations were performed in deepwater wells in the Caribbean Sea, saving up to two days of rig time by using a single intervention to isolate the openhole length from 600 to 1500 m and allowing continued, timely operations. A case study of this operation is presented that discusses the experience and lessons acquired, which should be beneficial for the industry.

Conventional balanced plugs are not efficient in openhole lengths greater than 500 ft because of operational limitations and design considerations. In such scenarios, fit-for-purpose downhole tools can provide reliable solutions, such as using a release mechanism to safely place a cement plug of the necessary length with proper thickening time distributed along the volume pumped. This technique avoids the long WOC times necessary to achieve adequate compressive strength. The release tool enables running sacrificial pipe; placing cement through the sacrificial pipe; displacing cement slurry with a dart, which provides an indication of its latching at the surface; and disconnecting to retrieve the landing string. In the laboratory, a 500-psi slurry compressive strength was obtained after 6 hours and 15 minutes. This allowed the TOC to be tagged after 6 hours of WOC. Because this procedure does not require the 3 1/2-in. stinger to be pulled out of the plug, the risk of spacer contamination in the slurry was reduced. Based on laboratory results, three operations using the release tool and discussed design considerations were performed successfully for the first time in the Caribbean Sea, with no nonproductive time (NPT) or quality issues experienced, saving up to USD 500,000 for the operator. Laboratory tests, such as compressive strength, provided a good indication of the time necessary to tag the TOC, which met the operation objectives. The tool capabilities and operational and design considerations can be used as a reference for projects in similar environments that require alternatives with proven solutions. The main benefit was reduced operator costs for rig daily charges resulting from placing one plug rather than several balanced plugs. This was also beneficial for the mud company because a large spacer volume was not incorporated into the mud. Another benefit was allowing tagging of the plug in the same operation because of the short WOC.
Optimization and Application of Cluster Horizontal Well Drilling Technologies and Foamy Oil Flow in ML Block, Venezuela
Authors: Jin Fu , Xi Wang , Shunyuan Zhang
Published: October 2017

Located in south of Eastern Venezuela Basin, Orinoco Oilfield is the unique huge ultra-tight oilfield that has not been developed by scale in the world. The high-density tight oil is known for its high content of acids, heavy metals and asphaltenes with a viscosity of 1000-10000mPa·s. ML Block whose OOIP is 178*108bbl is situated in east of the oilfield, while cluster horizontal well drilling and cold production technologies are still under research there.

Based on precise geological researches numerical simulation was carried out to optimize cold production of ultra-tight oil with foamy oil flow patterns in horizontal wells, including optimization of well placement, well spacing and horizontal section length. The near-bit geo-steering drilling technology was applied on adjacent wells to test its performance, while an experiment was conducted with PVT apparatuses to examine the effect of pressure decline rates on foamy oil flow. A long core pressure depletion test was accomplished to reveal the effect of foamy oil flow on recovery factors.

Three-dimension cluster horizontal well drilling and completion technologies shall be applied to develop ultra-tight oil reservoirs in huge loose sandstones, with the near-bit geo-steering drilling technology that controls landing points and horizontal sections in real time, keeping the bit move ahead along the lower boundary of the reservoir. Therefore, recovery rates may be dramatically improved due to the gravity drainage of ultra-tight oil. The most appropriate spacing of horizontal wells (500-600m) and horizontal section length (800-1200m) were determined to achieve the maximum recovery rate. The experiment proves that the recovery rate improves as the formation permeability increases, which means the "worm hole" contributes to heavy oil extraction. Boreholes with relatively large diameters, extensive perforated holes and slotted liners may be used to complete wells. In order to take the most advantages of the foamy oil flow mechanism high displacement ESPs shall be used with the selected thinner squeezed at the bottom, otherwise PC pumps with the thinner added at the wellhead are recommended.

Cold production technologies applied in ML Block save the overall production cost by 15.2%, improving the ultimate recovery rate by 8.6%. The foamy oil flow theory is improved, while it is the first time to integrate foamy oil flow production technologies with cluster horizontal well drilling technologies and near-bit geo-steering drilling technologies. As a result, the overall production rate of tight oil was greatly improved and the average production life of wells was extended.
The Use of CFD Simulations to Compare and Evaluate Different Sizing Algorithms for Three-Phase Separators
Authors: Ahmed Tariq , Hamad Faik , Russell Paul A.
Published: October 2017

This paper presents a comparative study of two commonly used three-phase separator design procedures; Arnold and Stewart and Svrcek and Monnery. The procedures were developed based on droplet settling and retention time theories for the separation of gas, oil and water and are known to predict different separator geometries for the same operating conditions. These procedures were constrained to allow optimisation of the design but details of the constraints applied on the rational for their application are not available. To better understand these constraints, the two procedures for sizing a three - phase horizontal separator equipped with weir plate were investigated. Each procedure was used to calculate the geometries for three different sets of flowrates namely; fixed oil with varying gas and water, fixed water with varying gas and oil and finally fixed gas with varying oil and water. The calculated geometries determined from each procedure were then investigated using ANSYS Fluent to determine the separation achieved. To ensure that the ANSYS Fluent simulations accurately defines the separation process, a small scale industrial separator was modelled. Simulation results in terms of the separator outlet quality predicted that the separator designed using Arnold and Stewart procedure has a greater separation efficiency than that designed by Svrcek and Monnery.
Application of Lasers for Perforation of Petroleum Wells
Authors: da Silva M. G. , Braga A. M. , de Faria G. V. , Rosario F. F
Published: October 2017

This thesis presents the results of a study evaluating the application of high powered lasers when perforating cement-lined wells in carbonate rock reservoirs. The focus is on the creation of lateral channels in the walls of the well to allow the flow of the oil into the well. Through an intensive literature review of the international patents published in the last decade, the current state-of-the-art use of lasers in the perforation of rocks was evaluated. Specifically, 226 patent documents were found to have been published since 2008, showing the great importance of lasertechnology in this field. The results of the microtomography analysis are presented, showing samples of the cement slurry formulation used in pre-salt wells and carbonate rocks with characteristics close to the ones found in these types of reservoirs. The fiber laserutilized presented an output of up to 1.5kW and a wavelength of 1,064µm. To evaluate the structure of the samples, X-ray tomography and microtomography were employed. The specific energy was estimated at 243 J/mm3 for the carbonate rocks. The final tests to represent the well architecture were realized with samples of liner/cement/carbonate. By means of lasers with the power of 1.5kW for 80 seconds, channels with 5mm diameters and 50mm depths were produced. The results obtained show, although only preliminarily, the potential of using this technology in perforation operations.
Evaluation of Gas Hydrates Operation Zone to Establish an Optimal Hydrate Management Strategy
Authors: Fossen Martin , Johnsen Heidi , Kilaas Lars , Shmueli Andrea
Published: October 2017

Years of research and development, as well as field experience has moved the hydrate management philosophy towards less conservative operations. Previously, the standard was to avoid gas hydrates altogether. Now, on the other hand, the industry is more often looking into how to "live with hydrates" meaning that they are willing to accept the risk of hydrate formation given that there are enough evidence that the hydrates will not plug the pipeline. This paper presents some of the experimental techniques and methods used to realize an effective hydrate management strategy by investigating hydrate properties with regard to plugging and possible slurry transport.
The Longest Horizontal Section Ever Drilled in an Extended-Reach Well in Brazil
Authors: Kenupp Rafael , Lourenço Affonso , Soltvedt Stian , Thomson Ian , Hughes Baker , Simões Grazielli , Morosov Daniela L. , Andrade Raquel
Published: October 2017

The Peregrino project, located in the post-salt zone of the Campos basin, imposes immense challenges for drilling extended- reach wells. This paper shares the accomplishments and challenges imposed by the well profile and downhole environment on the design and execution phases. Information is included about the solutions deployed that guaranteed reaching the target depth as planned, provides details about the well planning methodology, bottomhole assembly (BHA) design practices, drill bit selection as well as data monitoring and procedures for maximizing the transfer of power downhole and minimizing rock cutting energy. In summary, this paper reviews the details behind the successful drilling of 2268 meters inside a depleted reservoir section. A rotary steerable system was combined with a modular positive displacement motor while geosteering per a geologist's instructions in a drilling scenario of high torque, low weight on bit and water-based drilling fluid, without any trips to change the drill bit. The synergy between the operator and service companies was translated into practical steps, demonstrating that the collaborative approach was relevant and made it possible for drilling further.
Developments and Optimizations in the Pre-Salt Risers Systems: From Initial Technical Challenges up to Future Expectations
Authors: de Oliveira R. Caldeira , Gasparetto V. , Oazen E. V. , Senra S. F. , Aguiar L. L. , Valença C. J. , Lima D. L. , Carrara W. , Lemos C. A. D.
Published: October 2017

This paper aims to describe developments in the Santos Basin Pre-Salt risers systems, which in some few years experienced many different concepts to overcome big challenges. This paper also describes initiatives to optimize configurations with evolution and maturity of riser technologies and expectations for future developments.

In Santos basin Pre-Salt cluster, due to the challenging environmental conditions, presence of H2S and CO2, water depth up to 2310m, production riser's insulation requirements, relatively high temperature and high pressure, the riser system design for this scenario was something innovative and challenging for the industry. Currently, due to lower oil prices, an even more complex scenario is in evidence, imposing even greater challenges for risers systems regarding cost reduction. The experience acquired with the implementation of the first projects was a key factor to find viable and comprehensive ways to optimize cost.

In approximately 7 years of production in the Santos basin Pre-Salt layer, oil production surpassed 1 million bpd by using several different riser concepts: BSRs (Buoy-Supported Risers), SLWRs (Steel Lazy Wave Risers), Flexible Lazy Wave Risers, Free Hanging Flexible Risers and FSHRs (Free Standing Hybrid Risers). Nowadays, with greater maturity and new design premises, considerable cost reduction results have been obtained, mainly motivated by the reduction of buoyancy modules and reduction of riser sections quantity in the flexible risers. For the future, there are other ongoing optimizations studies to apply both flexible and rigid risers in free hanging configuration.

In early stages of project development, an extensive engineering work on riser analysis, the establishment of new design premise and some changes on current design process were done through a joint effort by operator, partners and suppliers. These are key factors for the achievement of considerable cost reduction. The maturity reached with the riser system designs was obtained through several design cycles, whose process can bring more future cost reductions.
Study of the Effect of Monoethylene Glycol MEG on the Precipitation of Calcium Carbonate in a Pressurized Dynamic System
Authors: Kartnaller V. , Venâncio F. , Cajaiba J. , Rosário F. do
Published: October 2017

Scale build-up in petroleum production systems is a major impediment to efficient oil and gas production. Calcium carbonate is one of the most commonly occurring sources of scale, but the formation of gas hydrate is also a challenge, especially in offshore and subsea deep water production. Thermodynamic inhibitors like monoethylene glycol (MEG) are frequently used to prevent hydrate formation. This paper describes the influence of MEG on the calcium carbonate scaling time by using a Dynamic Scale Loop System (DSL). The study also examines the influence of temperature, pressure and salt concentration on the scaling time. Experiments were performed using a 25-1 fractional factorial experiment design. The experiments showed that as MEG content increases, the expected calcium carbonate scale decreases. In contrast, an increase in temperature, will increase the calcium carbornate scale, while pressure and salt concentration did not have a significant influence on their own. Furthermore, the paper describes the interaction between the variables under review. The interaction between pressure, temperature and MEG content results in an overall decrease in MEG performance to avoid scale build-up by changes in the system's viscosity. Finally, we determine that the increase of MEG content increases the time to reach full-scale blocking; thus, the results indicate that an inhibition of the calcium carbonate deposition occurs as the MEG content increases.
Integrated Solution for Deepwater Cementing Challenges: Case Histories
Authors: Brunherotto Leonardo , Ribeiro Danilo , Perez Miguel Vicente
Published: October 2017

The primary objectives of well construction are to maximize reservoir deliverability, reduce remedial operations, and minimize nonproductive time (NPT) during the drilling and cementing process. Challenges associated with designing and delivering dependable barriers in deepwater environments include low bottomhole circulating temperatures (BHCTs), temperature variance, narrow pressure margins, annular pressure buildup (APB), etc. Cementing operations in these conditions should be engineered such that the equivalent circulating density (ECD) does not exceed the fracture gradient during cement-slurry placement. Additionally, lost circulation materials (LCMs) should be incorporated into the cement slurry to help control loss zones. This paper discusses the field implementation procedures and the cement-slurry design tailored for deepwater wells in offshore Brazil, which helped minimize risks and achieve the zonal-isolation objectives for extending the life of the well.