This paper describes the challenges faced on the deployment of intelligent well completion (IWC) systems in some of the wells built in Buzios field, mostly related to heavy fluid losses that occurred during the well construction. It also presents the solutions used to overcome them. This kind of event affects not only drilling and casing cementing operations, but may also prevent a safe and efficient installation of the completion system as initially designed. The IWC design typically used in Brazilian pre-salt areas comprises cased hole wells. Perforation operations must be performed before installing the integral completion system, as it does not include a separation between upper and lower completion. Therefore, the reservoir remains communicated to the wellbore during the whole completion installation process, frequently requiring prior fluid loss control as to allow safe deployment. Rock characteristics found in this field make it difficult to effectively control losses in some of the wells, requiring the use of different well construction practices that led to the development of some new well designs. The well engineering team developed a new well concept, where a separated lower completion system is installed in open hole, delivering temporary reservoir isolation. This new well architecture not only delivers reduced drilling and completion duration and costs, but also provides the IWC features in wells with major fluid losses. This is possible by the use of multiple managed pressure drilling (MPD) techniques when required, which were considered since the initial design phase. Safe and effective construction of some wells in pre-salt fields was considered not feasible before the adoption of MPD solutions, both for drilling and completions. Other important aspects considered on the new well design are the large thickness and high productivity of Buzios field reservoirs, as well as the need of some flexibility to deal with uncertainties. Finally, the new completion project was also designed to improve performance and safety on future challenging heavy workover interventions. The well construction area has gradually obtained improved performance in Buzios field with the adoption of the new practices and well design presented in this paper. The new solutions developed for Buzios field have set a new drilling and completion philosophy for pre-salt wells, setting the grounds for future projects. The improved performance is essential to keep these deepwater projects competitive, especially in challenging oil price scenarios. One of the groundbreaking solutions used is the possibility of installing the lower completion using managed pressure drilling techniques.

Pre-salt heterogeneous carbonate reservoirs typically present long net pays, high production/injection rates and some flow assurance risks. This paper presents general information, results and lessons learned regarding the installation of Intelligent Well Completion (IWC) in Santos Basin Pre-Salt Cluster (SBPSC) wells. It also presents some important improvements to be introduced in the future IWC systems specification and qualification based on the lessons learnt in these projects, setting some new challenges to the industry. The benefits expected with the use of IWC are achieved at the expense of challenging well engineering, since well completion design becomes more complex and well construction risks increase. Detailed and integrated planning is essential for the success of the operations, starting at the earliest phases of the well design and continued through detailed execution plans. The use of standardized practices and procedures has led to significant increases on installation performance. On the other hand, an open mind and a constant search for improvements allowed new solutions and procedures to be developed throughout the years. Regarding the system integration, a flexible and standardized control architecture was developed to allow combining different IWC providers and subsea vendors, which proved to be a successful approach. The most important improvement in IWC installation was the anticipation of the acid stimulation, nowadays performed before the vertical Wet Christmas Tree (WCT) installation. In order to achieve this goal some crucial improvements were gradually implemented in the stimulation practices, such as, an initial injectivity increase solution and some new acid diversion solutions, which allowed eliminating the use of coiled tubing and, as a consequence, the need of a subsea test tree. The well design team conducted an integrated risk assessment to properly evaluate the new practices and establish some actions to reduce the risks. Intense communication between production zones was observed during the acid job in some of the initial wells, ruining the gains of the IWC. After a comprehensive analysis, some possible causes were identified and with the new stimulation practices this issue was eliminated. Over the years, with the introduction of several improvements, some of them presented in this paper, the well completion duration was reduced to less than 50% of the one observed in the initial wells. This major performance increase has been essential to keep this deepwater projects feasible, especially in the oil scenario seen in recent years. Some of the new practices and lessons learned in this 100 wells equipped with IWC has set groundbreaking practices for Brazilian pre-salt fields development and may stand as a reference for the industry in similar deepwater projects. Additional requirements for future systems are expected to improve even further the performance in this scenario.

This paper presents the findings of a comprehensive structural analysis in which the influence of thermal transient pressure behavior on the trapped annuli in an injection well in a Brazilian pre-salt field was assessed, mainly motivated by physical evidence of a well failure. The study focus on a transient heat flow in radial direction during a well failure investigation, and its impact in tubular design safety factor under a given casing design methodology. During the investigation of this well integrity failure, a thermal analysis was performed considering the well construction history, but standard simulations using a world-class commercial software was not enough to explain the failure. Thus, a modified thermal analysis for casing and tubing was made in order to evaluate the design safety factor during each operation. This modified thermal analysis consists in splitting each operation in short time steps, in order to capture the short transient behavior. It was found that, during short transient time, the collapse stresses reached higher values than predicted in the previous standard steady-state modeling. Such result is basically related to the transient effect caused by radial heat flow. Based on theoretical studies and comparing them to downhole P&T sensors in confined annuli, a correlation was stablished and showed the importance of this type of analysis. In certain scenarios, where the confined annuli are subjected to progressive and non-proportional cooling down effect between the casing layers, a sudden pressure drop may occur in the internal side of the casing, without reaching the same pressure drop on the external side, which can lead to a dramatic external differential pressure for a given string. In wells with multiple confined annuli, such as in ultra-deepwater projects, this type of analysis represents a greater challenge. The results obtained so far have shown that the permanent and transient radial heat flow cannot be neglected in some scenarios and, therefore, open a new frontier for well design, especially when the tubing and multiple casing trapped annuli are subjected to rapid transient cool down.

A physical evidence of an injector well failure caused by transient thermal behavior in cooling operations has lead to technical actions in order to provide a safe operational envelope. A modified thermal analysis was developed to predict the transient thermal behavior that can result in a cascade casing collapse. The as built approach was applied in a number of wells already constructed in a Brazilian offshore field resulting in a better way for selecting which mitigation method can be appropriate for each case. One of the main results from the study was to establish a controlled injection flow rate in order to avoid a cascade casing collapse due to thermal shock in the wellbore. In some cases, it was necessary to provide an annulus pressure communication in the wellhead using a ROV for bleeding off the excessive pressure in C annulus. With these actions, the wells studied were able to present a safe operational envelope. The approach commonly employed in the industry takes into account just steady state injection operations, which are not enough to describe what is happening in the field and also are not sufficient to support a suitable casing design. The industry must put efforts to develop and consolidate a methodology based on transient thermal analysis to deal with thermal shock events in the well, as proposed in this paper. Furthermore, this work also proposes four alternatives to mitigate the well integrity loss based on the transient thermal simulations and a comprehensive well risk assessement.

This paper presents the finite element analysis of salt-creep behavior on deepwater wells with trapped annulus, considering cooling effects caused by injection operations. In addition, this effect was considered coupled with salt-creep behavior and its influence on casing collapse design under transient and steady state well operation. The scenarios of injection flow rate and temperature profile were analyzed using the coupled approach, for salt creeping and thermal trapped annulus. The wellbore profile is a typical Pre Salt Brazilian Offshore, where rock salt layer is confined under two casing shoes. The injection wells operation results in a pressure decrease in a confined annulus due to thermal cooling between casing and salt formation. Due to this pressure drop on the trapped annulus, the salt creeping behavior tends to increase, and proper casing stress verification must be done. The finite elements analysis for salt creeping was modeled using commercial finite elements software package, and thermal profile for transient and steady state injection was obtained using thermal casing design software. The coupled effects were evaluated using commercial casing design software. Preliminary studies have shown that there is a great influence on the salt creeping response on confined annulus when subjected to a pressure decrease due to thermal cooling on trapped annulus, caused by water injection operation. It is observed that there is a growth of the confined annular pressure due to salt creeping effects and that there is an acceleration in this phenomenon. The analysis also shows that casing collapse safety margin is time dependent considering a given operation. After well shutdown, the natural heating of the confined annulus occurs due to geothermal effects, and this pressure is added to the trapped annulus, increasing the pressure of trapped annulus. The final pressure is the sum of the salt pressure build up accelerated by the cooling steady state regime and geothermal pressure build up, during shutdown. The worst case scenario could be during restart the well injection, in that way, this kind of situation must be analyzed, so that it does not lead to critical situations on the casing design. Historically, according to literature review, only the annular pressure build up with production heating is analyzed. This work is a novel approach where annular pressure drop off, caused by cooling operations, was investigated including coupled salt-creeping and thermal phenomenon.