bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
Scope/Objectives: In order to meet the technical challenges of larger platforms in ultra-deep water (&gt; 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.
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

Abstract
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

Abstract
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.