Technical Challenges for Offshore Heavy Oil Field Developments

Abstract

Summary This paper discusses technical challenges and technology development opportunities associated with developing and producing offshore heavy oil (OHO) reservoirs, with emphasis on projects in cold or deep waters. The paper addresses how the reservoir and fluid characteristics will impact reservoir characterization, development concept selection, well construction, reservoir performance, artificial lift requirements, flow assurance, and operations. The applicability of common onshore heavy oil practices to OHO developments will be discussed. Emerging technologies and technology development opportunities will also be discussed. The material presented in this paper will be of particular interest to technology development personnel and asset team personnel who are in the appraisal or concept selection stages of a project; however, additional information is provided which may also be valuable later in the project life. Introduction Heavy oil reservoirs (those with API gravity < 20 deg, ? > 0.934) have been produced onshore successfully for decades in many basins around the world. There are also numerous examples of offshore heavy oil developments in shallow waters and gentle surface conditions, including those cited here from California (USA), Campeche (Mexico), Italy, and Brunei, respectively.1,2,3,4 Fields in shallow water but with harsh surface conditions have been developed or are still being evaluated in the North Sea.5 Recently, other OHO developments have been contemplated in cold water areas with sea ice (Jeanne d'Arc Basin, Canada) or in deep waters. With exploration efforts focused on deepwater basins such as those in West Africa and Brazil where heavy oil has already been found, significant additional heavy oil discoveries are likely. Heavy oil reservoirs tend to be low energy, low GOR systems with high viscosities and inferior crude properties. These projects tend to have low recovery efficiency and low productivity as compared to lighter oil reservoirs. OHO pro-jects typically have higher costs per unit volume of hydrocarbon (Capex and Opex). Investment requirements and operating challenges are even greater in cold or deep waters. These attributes combine to impact the entire value chain of OHO developments, from the appraisal process, through concept selection, development, operation, and even marketing of the oil. Technical advances are needed that can directly address the attributes described above, such as efficient recovery processes, enhanced productivity, reduced development costs, and improved crude value. In addition to the technical challenges associated with OHO, the larger investments and lower market values add a significant challenge to the economics of these offshore developments. Some OHO projects are moving forward but significant technical advances are needed to realize improved economic returns. Other OHO discoveries have been put on hold due to the combined technical and economic challenges. The technologies required to develop, produce, and market these reserves require the integration and optimization of skill sets from across the petroleum value chain, especially onshore heavy oil expertise and deepwater development skills. Identifying the key technical challenges and value drivers that are common to these projects, effectively developing and deploying technical solutions, and effectively learning from experiences on previous projects will be crucial for the success of future OHO projects.