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Well Containment Analysis – WCA - is a set of integrity analysis criteria in a shut in scenario performed during the well design phase. The installation of a capping and shut in of the well shall not induce hydrocarbon leakages to the seabed. One of the integrity analysis criteria within WCA is a situation in which the well, in a blowout scenario, is closed with the capping, and a fracture is then initiated at a specific casing shoe of the well, propagating through shallow formations. The analysis ensures that the time for fracture propagation to reach the mudline is longer than the time to drill a relief well and have the well controlled. When considering a situation of a fracture propagation in a blowout scenario after capping and controlling the well there are two main possibilities: (I) a shallow reservoir can absorb the hydrocarbon flow from a deeper reservoir, (II) the time required for the fracture propagation to reach the seabed is greater than the time needed to control the well in blowout situation, guaranteeing that there is no fluid broaching to the seabed. When considering the time for fracture propagation, a safety margin is needed due to uncertainties in the geological data. This work aims to present a few case studies where well projects didn’t attend WCA analysis considering P90 pore pressure scenario and needed further analysis to ensure attendance of well integrity. In this situation, studies were done considering fracture propagation beginning after the well closure due to a hypothetic blowout, trying to analyze if hydrocarbons would broach to the mudline, and if so, how much time such an event could occur. Study results show the impact of geology and geomechanics on fracture propagation. There are situations in which the fracture remains confined due to the presence of a shallower reservoir and others where the fracture broaches to the mudline in a short amount of time. This analysis has the potential to turn the concept of well integrity more flexible, allowing the well designer to combine, in a tentative optimal way, a safe and feasible design in more challenging scenarios.

An appraisal well was drilled in Brazilian pre-salt area using overbalance drilling fluid, with conventional techniques. While drilling reservoir (in a 12 1/4" phase), total losses were found. Unsuccessful attempts with LCM and cement pills revealed that only MPD/PMCD techniques could deliver the well to TD. It was decided to anticipate the installation of the 9 5/8" casing, covering only the upper portion of the reservoir, and well was suspended. The remaining reservoir could be drilled later with a rig equipped with MPD system. This well was designed as a 2-zones intelligent completion in cased hole configuration. Due to the fluid losses a new design had to be considered. Due to reservoir uncertainties, definition on the separation between zones would only be taken after drilling the remaining reservoir section. To overcome this challenge without adding time and complexity to the overall design, the best solution was to perforate the cased hole section after drilling the remaining section, meaning doing it with reservoir communicated to the wellbore and in PMCD mode. Several options were evaluated to design the TCP operation in PMCD. Well control strategies, contingencies, thermal effects, and dynamic shocks were considered. The solution consisted in running the TCP with a closed string, without NRVs and having robust contingencies in case of washout or drillpipe failure after perforating. The well was drilled, and total fluid losses occurred again. It was then successfully perforated still in PMCD, then lower and upper completion were installed. Despite these challenges, this was the fastest intelligent completion in all Petrobras pre-salt fields so far.

This is a case study of a presalt well that required the use of 3 different MPD techniques to achieve its goals. The well was temporary abandoned when conventional techniques failed to reach the final depth. Total fluid losses in the reservoir section required changing the well design and its completion architecture. The new open hole intelligent completion design had to be used to deliver the selective completion in this challenging scenario. From the hundreds of wells drilled in the Santos basin presalt, there are some wells with tight or no operational drilling window. In order to drill these wells different MPD techniques are used. In most cases, the use of Surface Backpressure (SBP) technique is suitable for drilling the wells to its final depth. For the more complex cases, when higher fluid loss rates occur, the use of SBP and Pressurized Mud Cap Drilling (PMCD) enables the achievement of the drilling and completion objectives. After the temporary abandonment of this specific well in 2018, the uncertainty of the pore pressure could not ensure that the SBP and PMCD techniques would be applicable when reentering the well. To avoid difficult loss control operations, the completion team changed the intelligent completion design to include a separated lower completion, enabling its installation with the MPD system. Besides the previously used MPD techniques, the integrated final project considered an additional technique, Floating Mud Cap Drilling (FMCD), as one of the possible contingencies for the drilling and completion phases. Well reentry and drilling of the remaining reservoir section included the use all the previously mentioned MPD techniques (SBP, PMCD and FMCD). The lower completion deployment utilized the FMCD technique to isolate the formation quickly and efficiently, without damaging the reservoir. The planning and execution of the well faced additional difficulties due to the worldwide pandemic and personnel restrictions. The success from the operation was complete with no safety related events and within the planned budget. At the end, the execution team delivered a highly productive well with an intelligent completion system fully functional, through an integrated and comprehensive approach. MPD use on deepwater wells is relatively new. Different operators used several approaches and MPD techniques to ensure safety and success during wells constructions over the last decade. This paper demonstrates the evolution of MPD techniques usage on deepwater wells.

Summary The demand for ultradeepwater scenarios invoked the frequent application of managed pressure drilling (MPD) in the last few years. In an ultradeepwater scenario, oil companies face issues such as narrow pressure windows and severe loss zones. Many wells are considered undrillable without the aid of MPD technology. MPD operations need to be correctly evaluated with consideration given to increased time and cost/benefit analysis. In this paper, we propose a probabilistic model to evaluate MPD demand by estimating the optimal number of rigs equipped with MPD and a rotating control device (RCD), and we analyze which intervention strategy is the most cost– and time–effective. Reducing uncertainty is an important factor when making decisions about drilling. We adopted a Monte Carlo simulation using loss–zone estimation, probability of prediction error, the number of rigs equipped with MPD, and several strategies. Better MPD strategies were determined on the basis of available data and the optimal number of rigs equipped with an MPD system and RCD equipment, reducing subjectivity in the decision–making process. The originality of our paper lies in the new quantitative approach to dealing with uncertainty in the prediction of fluid losses and the cost and duration of different MPD strategies, numerically simulating the possible scenarios.

Manage Pressure Drilling is not a new technology, but the transition from land operation to floaters is still recent. This created a situation where drilling contractors and operators are still learning what the true capabilities of the technology are. MPD technology adoption on floaters can be divide it in 3 different phases: Use for Early Kick Detection and wellbore stability improvement;Introduction of Hydrostatically Underbalanced fluid;Influx circulation through the MPD system; In the first phase most of the procedures and barrier concepts stay untouched. After eliminating initial skepticism, second phase commences. Hydrostatic pressure exerted by the fluid is inferior to the formation pressure. Primary barrier concept alters. The technology can be applied to drill wells with narrow operational windows, unviable conventionally. Finally, third phase starts with very limited volumes being allowed to be circulated through the MPD system. After first successful influx circulations through the MPD system, increased volumes may be encouraged to be circulated through the primary barrier.

MPD techniques have being applied to drill zones with major fluid losses or narrow operational window. Nevertheless, subsequent operations are not yet at the same stage of development: Wireline logging, running casing and cementing are still challenging and need further development when it comes to DP rigs. Therefore, after drilling a well with hydrostatically underbalanced fluid and surface backpressure, it is necessary to replace the drilling fluid in order to continue the operations. Although, in nearly all MPD wells it is possible to do this, the major challenges are zones with absent drilling window and severe losses where PMCD technique is required. In these cases, it is not possible to use overbalanced drilling fluid. This paper presents a solution for wireline logging while using MPD techniques on DP rigs with underbalanced drilling fluid. At first, it shows the planning phase and its discussion, then the execution phase with its difficulties.

Given the complexity related to deepwater drilling with narrow operational windows, any effort to increase the confidence on the safety guidelines should be encouraged. There are many procedures in MPD operations that can be verified and validated during the operations, in order to avoid unforeseen situations. As initiatives to optimize the drilling process in real time are extremely important, the present study focuses on the development of specific methodologies to support MPD operations, which are implemented on a real time drilling diagnosis software [5]. It is very useful to review the drilling plan in various situations. With the use of MPD monitoring module is possible to obtain, from the DPPT (Dynamic Pore Pressure Test) and DFIT (Dynamic Formation Integrity Test) procedures, more precise values to compose the operating window. As a consequence of appliying it together with precise hydraulics, cutting transport and torque and drag models, the developed methodology proposes, as output, the ideal operating parameters, such as choke pressure, pump flow rate or adjustments related to the drilling fluid properties. The methodology always considers the best approach to meet the restrictions imposed by the operational window, avoiding drilling problems. Alternatively, if a change on the operating parameters is not sufficient, it also simulates the best position for the Anchor Point. The developed methodology was successfully applied in a number of MPD wells recently drilled in distinct deepwater locations, in Brazil. The real time optimization procedures proposed in the present paper are a further step to ensure the reliability of MPD operations in challenging scenarios, aiming enhanced efficiency and safety.

This paper describes how Managed Pressure Drilling (MPD) techniques can be used in some workover and completion operations, such as the lower completion replacement. It also presents the first application of this kind of solution in a subsea well, which has been recently done in Lula field in the Brazilian pre-salt. Highly stimulated wells in the Brazilian pre-salt carbonate reservoirs set significant challenges for well engineers when the lower completion must be replaced in workover operations. Major fluid losses are expected as the formation cannot be isolated from the wellbore. Costly loss control operations must be performed prior to the completion retrieval, introducing LCM in the well, causing formation damage and requiring further well cleaning and stimulation. A new approach was developed, in which MPD techniques such as Mud Cap Drilling (MCD) are used to cope with the fluid losses and avoid loss control operations and its associated impacts while maintaining a safe operation. The use of two of the MPD techniques, Pressurized and Floating Mud Cap Drilling (PMCD and FMCD), in the scenario previously described allow the use of sacrifice fluid, usually treated seawater, to continuously inject underbalance or overbalance fluid into the well and avoid hydrocarbons migration during operations with highly stimulated formations still connected to the well. This also allows monitoring the well for any well control issue, as well as applying well control procedures. Even in the FMCD technique a Rotating Control Device (RCD) is used below the drilling riser slip joint to prevent any possible gas migrated into the riser to reach the rotary table. The use of this kind of solution has turned the lower completion retrieval or replacement an operation with less deviation in terms of duration and budget. Costly loss control operations are avoided and there is no need to introduce loss control materials into the well, which could lead to problems when retrieving or installing the lower completion, such as stuck pipe or equipment failure. The customization of MPD techniques and the development of specific procedures for completion and workover with MPD have led to safe and more efficient operations in challenging subsea interventions with DP rigs. This new approach has set an alternative workover philosophy for some pre-salt wells and also opened new opportunities worldwide by the application of this innovative solution. A significant amount of wells equipped with intelligent completion in pre-salt areas do not have a separated completion that could temporarily isolate the formation during heavy workover interventions. In this scenario the use of MPD techniques like presented in this paper might be a valuable solution.

When compared to conventional drilling, MPD techniques provide a valuable tool to build challenging wells and reach new reservoirs. As MPD and MCD techniques lead to major changes on the way wells are drilled, the completion projects must be also adapted to this new scenario. In order to fully use MPD capabilities it is necessary to work with statically underbalance fluids. This fact may not be an issue during the drilling phase with the RCD, but impacts completion, as the RCD, which is suitable for a drillpipe, is not suitable for all completion strings and equipment. For MCD scenario, the necessity of periodic or constant injection down the annulus affects some completion equipment. Project requirements, safety standards, equipment capability and operational procedures must be reviewed, in order to cover the different scenarios of MPD (SBP) and MCD (FMCD and PMCD) wells. New completion standards were developed for deepwater and ultradeewater wells on MPD/MCD completion projects and sometimes even a full new completion design was required due to MPD techniques used. This paper presents the development history, results and considerations made for completion with MPD/MCD on Petrobras offshore wells in Campos and Santos Basins located in Brazil offshore.

MPD is a very powerful tool that is gaining momentum for deepwater offshore wells construction. A dynamic positioning rig adapted to MPD operations can apply different techniques that better suit to each well scenario. Currently Petrobras has over 20 MPD deepwater offshore wells drilled, having applied different techniques to achieve success: from "basic" SBP to MCD variants. This paper discusses the various MPD techniques that can be utilized from a dynamic position rig during deepwater well construction.

In recent years, PETROBRAS has been using MPD (SBP/MCD) technology in ultradeepwater scenarios at development and exploratory wells. Although MPD techniques are an advance over conventional drilling, it also brings more complexity to the operation and, in some cases, increases the duration and costs of the interventions when compared to conventional drilling. Ideally, the rigs equipped with MPD system should only be used in wells, or in specific phases of the well, that requires MPD to conclude or where the NPT associated with fluid losses is considerable. In these scenarios, the extra costs and extra time necessary are negligible, compared to the NPT avoided, and the alternative would be not to reach target depth or drill the well. Geomechanics, pore pressure estimation and loss zone identification are not an exact science. There is always an uncertainty in predicting MPD (SBP/MCD) demand, pushing the development of techniques and strategies to optimize the allocation of MPD rigs in wells where the NPT would be so high that the use of the MPD is advantageous, or, where MPD is an enabler of well construction. This paper describes a probabilistic analysis developed to support the determination of MPD (SBP/MCD) demand, calculating the optimum number of rigs to be equipped with MPD (SBP/MCD) and RCD system, and which intervention strategy is the most cost effective for a development campaign, based on historic results.

The development of the production phase of pre-Salt fields in Santos Basin have been facing many challenges, one of them is the occurrence of massive fluid losses during drilling, completion and evaluation operations. One possible solution to drill in this scenario is the usage of the Managed Pressure Drilling (MPD) techniques to minimize fluid loss and, in cases of massive losses, the use of the Mud Cap Drilling technique. This paper presents a case study of the drilling operations on a Santos Basin well that had major losses while using conventional drilling technique hence unable to reach all objectives. The well was successfully reentered using MPD/PMCD to successfully reach target reservoir and the details of the solution to reentry using MPD/PMCD and its successful results is presented It is described the use of MPD variants including the first use of PMCD on a DP rig on an offshore well in Santos Basin. MPD/PMCD proved an enabling technology when reentering a reservoir with major losses and absent drilling window. Design, execution and results of successful operations are covered.

A common Pre salt offshore well from Santos Basin in Brazil has a water depth superior to 2000m (6500 ft) about 2000m of salt and produce from a carbonate reservoir. The Pre-salt reservoir is a major driver on future production development for Petrobras. After several cases of severe circulation losses in the Pre-salt wells of Santos Basin, including the area of the well RJS-708, the previous drilling strategy was not proving to be reliable or effective. Loss control pills were ineffective while cement pills were time consuming and not providing satisfactory results. In this scenario arose the opportunity to apply the techniques of MPD (Managed Pressure Drilling) and MCD (Mud Cap drilling) as a contingency on the well RJS-708. The well had prediction of fractures or caves along the carbonate reservoir with high probability of circulation losses during the drilling of the reservoir phase. The potential benefits of the MPD technique were large due to the possibility of minimizing the volume of fluid lost to the formation through the management of downhole pressure. The MCD technique was also considered as contingency plan, for a scenario of total losses because of the inexistence of a drilling window, even considering the downrole pressure management near balanced. The work performed during 2013 included: Modification of the rig, training of the teams involved, preparation of MPD and MCD procedures for the drilling rig (First DP rig to use the system at Petrobras) and discussions of new procedures with the contractor. From the list of new procedures included the Dynamical Pore Pressure test, which proved to be a useful tool. The results obtained with MPD technique were excellent. In order to remain inside operational window, an underbalance mud weight with management of the surface back pressure was adopted to remain in an overbalance condition in front of the reservoir. The MPD system managed to be inside an operating window of 0.25 ppg without significant losses, and a time deviation of less than 4% from the initial schedule and no severe losses were observed during the construction of the well