Supported by the last events, it can be observed that safety must be the major concern in the activities developed in oil and gas well construction. However, safety assessment during the well construction process is not a trivial issue. Available risk evaluation approaches are based on static analyses of existent systems, not allowing a dynamic evaluation of the risk at each alteration of circumstances. This work proposes the use of quantitative and dynamic risk assessment (QDRA) to assess the degree of safety of each planned job. The QDRA is a type of "safe job analysis" approach, developed to quantify the "degree of safety" in the entire well construction process, as well as during maintenance activities. The proposed methodology presents the definitions of "barrier" and "integrated barriers set (IBS)", as well as the modeling technique showing their relationships and it compares it with the analysis presented at Norwegian standard (NORSOK D-010). This technique has been applied not only during the planning stages of well construction but also during workover to analyze the number of available IBSes for each operation. The greatest advantage of this technique is that it can be applied during the planning stages of well construction and maintenance, where the effects of hazard on the job sequence are important unknowns.

The development of digital transformation tools has significantly increased the amount of available data in recent years. As in all sectors of the economy, the oil industry, with a focus on well construction, was not left out of the process. Numerous data are monitored and stored in real time and several studies are carried out to increase operational performance. However, little has evolved in relation to the knowledge that these data can generate in decision-making processes, such as in the definition of targets that serve as a reference for the planning of interventions. Thus, this article explains a new methodology for defining targets, based on the knowledge of specialists, the concept of zero-based budgeting and risk analysis, with the integration of teams of well designers, reservoirs, and budgeting. The methodology was used in 19 fields’ studies and directly applied to the planning of 5 new projects.

The need to reduce costs, to increase the attractiveness of development projects in the mature fields environment is a necessary condition to allow the incorporation of new reserves and has led the oil industry to seek better practices in well construction. This paper presents the implementation of an adapted Zero-Base Budget (ZBB) methodology, which guided Petrobras to establish lean (but still viable) cost targets. This is one of the initiatives that constitutes Petrobras' RES20 Program, whose ambition is enabling 20 billion equivalent barrels of new reserves by the year 2030. Through a multidisciplinary effort, the ZBB identifies the lowest CAPEX well design, where some optimizations are considered, keeping the focus on safety. As an example of such new practices, we present in this paper one new design example applied to post-salt scenario, called TOT-3P. It is based on drilling the well in 3 sections and setting 2 casings, completing it by running in hole lower and upper completion together (TOT - True One Trip). The well design of 7-GLF-49H-ESS is a real example of this concept implementation, originally approved with an estimated average duration of 96.6 days. The original scope included drilling in 4 sections, with a pilot well and Open Hole Gravel Pack (OHGP) completion. Applying one of ZBB’s pillar, which considers the simplest feasible design, the well was built in 43.7 days, resulting in more than 50% time reduction. According to an external database, this duration is a "best in class", when compared to the industry, confirming the methodology potential to achieve the mature field’s economical requirements. Application of the proposed ZBB methodology in 19 fields of Petrobras’ portfolio, for pre-and post-salt scenarios, revealed a potential average reduction of 50% when compared to the field historical durations, considering all potential optimizations that could be implemented. Since the incorporation of the optimizations depends on the wells features, given that ZBB assumes some premises to adopt the lowest CAPEX design, a gap analysis becomes necessary in order to identify which optimizations can be incorporated. A list of 13 wells from 3 mature fields was analyzed, resulting in a maximum expected investment reduction of 29%. The potential cost reduction associated with well project ZBB optimization presents itself as a key enabler of mature fields re-development, that will allow for the incorporation of important volumes of reserves, increase the recovery factor in mature fields and reach the targets of the RES20 program.