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.

Buzios is a super-giant ultra-deep-water pre-salt oil and gas field located in the Santos Basin off Brazil's Southeastern coast. There are four production systems already installed in the field. Designed to use flexible pipes to tie back the production and injection wells to the FPSOs (Floating Production Storage and Offloading), these systems have taken advantage from several lessons learned in the previous projects installed by Petrobras in Santos Basin pre-salt areas since 2010. This knowledge, combined with advances in flexible pipe technology, use of long-term contracts and early engagement with suppliers, made it possible to optimize the field development, minimizing the risks and reducing the capital expenditure (CAPEX) initially planned. This paper presents the first four Buzios subsea system developments, highlighting some of the technological achievements applied in the field, as the first wide application of 8" Internal Diameter (ID) flexible production pipes for ultra-deep water, leading to faster ramp-ups and higher production flowrates. It describes how the supply chain strategy provided flexibility to cover the remaining project uncertainties, and reports the optimizations carried out in flexible riser systems and subsea layouts. The flexible risers, usually installed in lazy wave configurations at such water depths, were optimized reducing the total buoyancy necessary. For water injection and service lines, the buoyancy modules were completely removed, and thus the lines were installed in a free-hanging configuration. Riser configuration optimizations promoted a drop of around 25% on total riser CAPEX and allowed the riser anchor position to be placed closer to the floating production unit, promoting opportunities for reducing the subsea tieback lengths. Standardization of pipe specifications and the riser configurations allowed the projects to exchange the lines, increasing flexibility and avoiding riser interference in a scenario with multiple suppliers. Furthermore, Buzios was the first ultra-deep-water project to install a flexible line, riser, and flowline, with fully Controlled Annulus Solution (CAS). This system, developed by TechnipFMC, allows pipe integrity management from the topside, which reduces subsea inspections. As an outcome of the technological improvements and the optimizations applied to the Buzios subsea system, a vast reduction in subsea CAPEX it was achieved, with a swift production ramp-up.

The Oil and Gas industry has faced an unpredictable and fast transformation in the last years. At first, there were barrel prices over U$ 100 dollars, which motivated a huge worldwide investment that pushed operators and the supply chain to respond to unprecedented growth. Due to the downturn in the oil prices, the challenge has moved towards achieving project feasibility in a low Brent scenario. The Brazilian subsea oil and gas industry has struggled with this context. Initially, with the Pre-Salt discoveries in 2006 it was necessary to develop breakthrough technological solutions to face this new frontier and to build 10 ultra deep-water production systems happen in just 10 years. Due to the recent price drop, Petrobras subsea engineering area has faced a demand to develop simpler and cost efficient solutions to reduce Pre-Salt CAPEX and OPEX. The objective of this paper is to review how Petrobras subsea area is dealing with these challenges since the discovery of Pre-Salt in 2006 until the current downturn of the oil and gas industry. As a reaction to that, Petrobras has been running an internal strategy called Subsea Cost Reduction Plan - PRCSub. The main purpose of this program is to search for the biggest cost reduction opportunities and to promote a full integration among Petrobras subsea team and suppliers. The PRCSub has delivered excellent results. Around US$ 500 million in savings were registered between 2014 and 2015 in the subsea scope, and between 25% of CAPEX reduction was achieved in Pre-Salt developments due to optimization initiatives for subsea design. The paper will present a review of the initiatives, describing the technical solutions and the new business model under construction by Petrobras.

Brazilian pre-salt production development brought up a series of technological challenges to Petrobras over the last two decades. Despite all the innovations that have made feasible to produce oil in ultra-deep water, the deployment schedule of these projects still showed opportunities for improvement, according to other companies’ benchmark. Given the economical attractiveness of reducing the production schedule of greenfield development and the current increase of Petrobras production output subject to the term restrictions of the Production Sharing Contract, a strategic program has been implemented with focus on reducing the elapsed time since oil discovery until the start of its commercial production, also called PROD1000. This program considers all activities of a production development project, searching for optimizing governance, design, construction stages and deployment of production system so that first oil is anticipated. In subsea system, the term reduction strategy was based on four main pillars: interfaces pretreatment (ex. subsea & FPSO), agile bidding process, subsea components standardization and prequalification of suppliers.