The evolution of deepwater production cannot be discussed without mentioning the contribution of Petrobras’ upstream activity. The reason is Petrobras’ success in overcoming enormous technological challenges in deep water during the last decade.
I joined Petrobras in 1986, when our production was around 0.6 million B/D, mainly from onshore and shallow-water operations. With the enormous pressure on the Brazilian trade balance from high-priced oil imports, it became imperative to increase domestic supplies. The only area capable of yielding a significant increase in national oil production was the Campos basin. The Marlim and Albacora giant field discoveries during 1985–86 at water depths up to 1000 m brought new opportunities and challenges that promoted enormous technological advancement in the petroleum industry in the following decades. I find it exciting that, 25 years after I joined the company, Petrobras’ oil production has now reached 2 million B/D, an increase—mostly from deep water—of almost 1.5 million B/D.
Technological Innovation in Deep Water
The greatest technological innovations in deep water were made in marine structures, submarine production systems, risers, and flexible lines. In the case of risers and submarine pipelines, the flexible-lines evolution over the last 30 years has given the industry the capability of producing in water depths from 100 m to more than 2000 m, with a wide range of diameters. These advanced pipelines were developed by vendors as a result of Petrobras’ requirements. Petrobras technicians, in turn, advanced deepwater technology with significant contributions in the development of top connectors, bending stiffeners, and prototype qualification processes.
Deepwater challenges have resulted in many other innovations in technology, including drilling and completion advances and flow assurance improvements necessitated by heavy-oil production from ultradeep water.
Other technology advances in the past several decades have helped get us to where we are today. The expansion of 3D seismic data acquisition, processing, and interpretation in deep water and the introduction of 4D seismic have helped in production processes’ planning and monitoring. Reservoir monitoring has become crucial in optimizing the development plan and defining drainage strategies for deepwater fields. The development and use of risk analysis and valuation methodologies have resulted in important tools that aid in justifying additional wells and expensive data acquisition. I remember when I was in charge of the Reservoir Technology Group at the Petrobras Research Center at the beginning of the new millennium and we had just started working with uncertainty analysis for production forecasting; now, this is standard procedure for all our offshore projects.
Thanks to such advances, during the ’90s, many new deepwater fields were discovered and several subsea records were broken. More and more wells were drilled at greater depths, leading us to the present day, where we drill and produce at depths of over 2000 m.
Deepwater Development Strategy
In general, there are two main development strategies for deepwater projects:
- Dry completion wells coupled to tension-leg platforms or spar systems
- Wet completion wells coupled to floating production, storage, and offloading (FPSO) vessels or semisubmersible platforms
Petrobras has favored the latter and subsequently has become a leader in wet completion wells. The main advantage of this option is flexibility because the drainage plan can be more easily altered or optimized later in the life of the field.
Petrobras’ strategy for deepwater development is based on several key elements, including the following:
- Good seismic data and a limited number of appraisal wells
- Extended well testing to perform dynamic appraisal and reduce reservoir uncertainty
- Phased development and early production systems working as a field-scale laboratory for definitive systems
- Low capital exposure and early reverse cash flow
The Challenge of Deepwater Projects
Deepwater projects are very complex and have multibillion-dollar price tags. Their performance is highly dependent on integration and cooperation among multidisciplinary teams of well-trained people, backward integration of facilities and well teams into reservoir teams, good project specifications, and a good contracting strategy.
In my opinion, the main concern related to these developments is the high capital-expenditure demand and long period of time before production return. Huge investments are needed up front when there is limited information about the reservoir, fluids characteristics, and possible flow assurance problems. My background is in reservoir engineering, so I feel comfortable dealing with subsurface uncertainties and risk analysis; but, sometimes, it is very difficult to communicate these issues to multidisciplinary teams so they can understand the importance of data acquisition and flexibility in the projects.
To overcome these challenges, operators must endeavor to do the following:
- Define the main uncertainties that could affect the development plan
- Implement a robust plan to mitigate the main uncertainties before the approval of the main contracts
- Provide flexibility in production and subsea systems to facilitate possible corrective changes and manage risks throughout project deployment
- Ensure high production rates at the beginning of the project to maximize economic indicators
- Provide flexibility to incorporate new production technologies, capable of reducing operational costs and increasing revenue
Extended Well Tests
A data acquisition program is critical to reduce reservoir uncertainties that could impact the deployment of future production systems. Extended well tests are part of the Petrobras tradition [or culture] to develop its giant fields in deep water. Petrobras has conducted them since 1996, using FPSOs anchored or dynamically positioned. They have proven to be an important source of dynamic information about the reservoir.
Among many other benefits, production over a longer period of time enables the evaluation of well damage and oil flow performance through long subsea lines. Furthermore, it is the basis on which one can draw conclusions about hydraulic continuity and the existence of geological faults. Early production in candidate areas is critical to reduce risks and optimize the drainage plan. We are very proud of the strides the company has made with extended well testing for deepwater projects.
What´s Next?
Our deepwater challenges are ongoing. We are now facing new presalt discoveries beyond 2200 m water depths, beneath a 2-km salt layer, in carbonate reservoirs, together with light oil with a high CO2 content. My team is currently working with technical and economic feasibility studies in order to implement huge production development projects for these presalt discoveries, which has been a great learning opportunity for me.
The complexity of the exploration and production process requires a very wide range of technologies for the efficient and safe production of oil and gas, wherever they are found. However, to achieve success, just having the technology available is not enough. It is also necessary and fundamental to know how to efficiently apply this technology in an integrated manner. This is only achievable through cooperative work between operational areas and research and development. On top of all this, the industry must learn how to manage challenging environmental regulations in the wake of the 2010 Macondo blowout.
